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Sample records for cryptic aminoglycoside resistance

  1. Rapid Aminoglycoside NP Test for Rapid Detection of Multiple Aminoglycoside Resistance in Enterobacteriaceae.

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    Nordmann, Patrice; Jayol, Aurélie; Dobias, Jan; Poirel, Laurent

    2017-04-01

    The rapid aminoglycoside NP (Nordmann/Poirel) test was developed to rapidly identify multiple aminoglycoside (AG) resistance in Enterobacteriaceae It is based on the detection of the glucose metabolism related to enterobacterial growth in the presence of a defined concentration of amikacin plus gentamicin. Formation of acid metabolites was evidenced by a color change (orange to yellow) of the red phenol pH indicator. The rapid aminoglycoside NP test was evaluated by using bacterial colonies of 18 AG-resistant isolates producing 16S rRNA methylases, 20 AG-resistant isolates expressing AG-modifying enzymes (acetyl-, adenyl-, and phosphotransferases), and 10 isolates susceptible to AG. Its sensitivity and specificity were 100% and 97%, respectively, compared to the broth dilution method, which was taken as the gold standard for determining aminoglycoside resistance. The test is inexpensive, rapid (<2 h), and implementable worldwide. Copyright © 2017 American Society for Microbiology.

  2. AMINOGLYCOSIDE RESISTANCE GENES IN Pseudomonas aeruginosa ISOLATES FROM CUMANA, VENEZUELA

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    Bertinellys TEIXEIRA

    2016-01-01

    Full Text Available The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC, aminoglycoside-adenyltransferases (AAD, and aminoglycoside-phosphotransferases (APH, is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137 were identified from the Intensive Care Unit (ICU, mainly from discharges (96/137. The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively. Phenotype VI, resistant to these antibiotics, was the most frequent (14/49, followed by phenotype I, resistant to all the aminoglycosides tested (12/49. The aac(6´-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.

  3. AMINOGLYCOSIDE RESISTANCE GENES IN Pseudomonas aeruginosa ISOLATES FROM CUMANA, VENEZUELA.

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    Teixeira, Bertinellys; Rodulfo, Hectorina; Carreño, Numirin; Guzmán, Militza; Salazar, Elsa; De Donato, Marcos

    2016-01-01

    The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC), aminoglycoside-adenyltransferases (AAD), and aminoglycoside-phosphotransferases (APH), is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA) were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137) were identified from the Intensive Care Unit (ICU), mainly from discharges (96/137). The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively). Phenotype VI, resistant to these antibiotics, was the most frequent (14/49), followed by phenotype I, resistant to all the aminoglycosides tested (12/49). The aac(6´)-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´)-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.

  4. Identification of aminoglycoside and β-lactam resistance genes from within an infant gut functional metagenomic library.

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    Fiona Fouhy

    Full Text Available The infant gut microbiota develops rapidly during the first 2 years of life, acquiring microorganisms from diverse sources. During this time, significant opportunities exist for the infant to acquire antibiotic resistant bacteria, which can become established and constitute the infant gut resistome. With increased antibiotic resistance limiting our ability to treat bacterial infections, investigations into resistance reservoirs are highly pertinent. This study aimed to explore the nascent resistome in antibiotically-naïve infant gut microbiomes, using a combination of metagenomic approaches. Faecal samples from 22 six-month-old infants without previous antibiotic exposure were used to construct a pooled metagenomic library, which was functionally screened for ampicillin and gentamicin resistance. Our library of ∼220Mb contained 0.45 ampicillin resistant hits/Mb and 0.059 gentamicin resistant hits/Mb. PCR-based analysis of fosmid clones and uncloned metagenomic DNA, revealed a diverse and abundant aminoglycoside and β-lactam resistance reservoir within the infant gut, with resistance determinants exhibiting homology to those found in common gut inhabitants, including Escherichia coli, Enterococcus sp., and Clostridium difficile, as well as to genes from cryptic environmental bacteria. Notably, the genes identified differed from those revealed when a sequence-driven PCR-based screen of metagenomic DNA was employed. Carriage of these antibiotic resistance determinants conferred substantial, but varied (2-512x, increases in antibiotic resistance to their bacterial host. These data provide insights into the infant gut resistome, revealing the presence of a varied aminoglycoside and β-lactam resistance reservoir even in the absence of selective pressure, confirming the infant resistome establishes early in life, perhaps even at birth.

  5. In Silico Assigned Resistance Genes Confer Bifidobacterium with Partial Resistance to Aminoglycosides but Not to Β-Lactams

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    Fouhy, Fiona; O’Connell Motherway, Mary; Fitzgerald, Gerald F.; Ross, R. Paul; Stanton, Catherine; van Sinderen, Douwe; Cotter, Paul D.

    2013-01-01

    Bifidobacteria have received significant attention due to their contribution to human gut health and the use of specific strains as probiotics. It is thus not surprising that there has also been significant interest with respect to their antibiotic resistance profile. Numerous culture-based studies have demonstrated that bifidobacteria are resistant to the majority of aminoglycosides, but are sensitive to β-lactams. However, limited research exists with respect to the genetic basis for the resistance of bifidobacteria to aminoglycosides. Here we performed an in-depth in silico analysis of putative Bifidobacterium-encoded aminoglycoside resistance proteins and β-lactamases and assess the contribution of these proteins to antibiotic resistance. The in silico-based screen detected putative aminoglycoside and β-lactam resistance proteins across the Bifidobacterium genus. Laboratory-based investigations of a number of representative bifidobacteria strains confirmed that despite containing putative β-lactamases, these strains were sensitive to β-lactams. In contrast, all strains were resistant to the aminoglycosides tested. To assess the contribution of genes encoding putative aminoglycoside resistance proteins in Bifidobacterium sp. two genes, namely Bbr_0651 and Bbr_1586, were targeted for insertional inactivation in B. breve UCC2003. As compared to the wild-type, the UCC2003 insertion mutant strains exhibited decreased resistance to gentamycin, kanamycin and streptomycin. This study highlights the associated risks of relying on the in silico assignment of gene function. Although several putative β-lactam resistance proteins are located in bifidobacteria, their presence does not coincide with resistance to these antibiotics. In contrast however, this approach has resulted in the identification of two loci that contribute to the aminoglycoside resistance of B. breve UCC2003 and, potentially, many other bifidobacteria. PMID:24324818

  6. In silico assigned resistance genes confer Bifidobacterium with partial resistance to aminoglycosides but not to β-lactams.

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    Fiona Fouhy

    Full Text Available Bifidobacteria have received significant attention due to their contribution to human gut health and the use of specific strains as probiotics. It is thus not surprising that there has also been significant interest with respect to their antibiotic resistance profile. Numerous culture-based studies have demonstrated that bifidobacteria are resistant to the majority of aminoglycosides, but are sensitive to β-lactams. However, limited research exists with respect to the genetic basis for the resistance of bifidobacteria to aminoglycosides. Here we performed an in-depth in silico analysis of putative Bifidobacterium-encoded aminoglycoside resistance proteins and β-lactamases and assess the contribution of these proteins to antibiotic resistance. The in silico-based screen detected putative aminoglycoside and β-lactam resistance proteins across the Bifidobacterium genus. Laboratory-based investigations of a number of representative bifidobacteria strains confirmed that despite containing putative β-lactamases, these strains were sensitive to β-lactams. In contrast, all strains were resistant to the aminoglycosides tested. To assess the contribution of genes encoding putative aminoglycoside resistance proteins in Bifidobacterium sp. two genes, namely Bbr_0651 and Bbr_1586, were targeted for insertional inactivation in B. breve UCC2003. As compared to the wild-type, the UCC2003 insertion mutant strains exhibited decreased resistance to gentamycin, kanamycin and streptomycin. This study highlights the associated risks of relying on the in silico assignment of gene function. Although several putative β-lactam resistance proteins are located in bifidobacteria, their presence does not coincide with resistance to these antibiotics. In contrast however, this approach has resulted in the identification of two loci that contribute to the aminoglycoside resistance of B. breve UCC2003 and, potentially, many other bifidobacteria.

  7. Aminoglycoside resistance among isolates of nosocomial Enterobacteriaceae

    International Nuclear Information System (INIS)

    Botha, P.L.; Elisha, G.; Pratt, K.

    1981-01-01

    Fifty-seven gentamicin-resistant isolates of Enterobacteriaceae, obtained from patients attending hospital, were examined for the production of aminoglycoside-modifying enzymes. Of the 51 strains producing such enzymes, 34 were presumptively plasmid-mediated as indicated by conjugation experiments

  8. Cytosolic proteome profiling of aminoglycosides resistant Mycobacterium tuberculosis clinical isolates using MALDI-TOF/MS

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    Divakar Sharma

    2016-11-01

    Full Text Available Emergence of extremely drug resistant tuberculosis (XDR-TB is the consequence of the failure of second line TB treatment. Aminoglycosides are the important second line anti-TB drugs used to treat the multi drug resistant tuberculosis (MDR-TB. Main known mechanism of action of aminoglycosides is to inhibit the protein synthesis by inhibiting the normal functioning of ribosome. Primary target of aminoglycosides are the ribosomal RNA and its associated proteins. Various mechanisms have been proposed for aminoglycosides resistance but still some are unsolved. As proteins are involved in most of the biological processes, these act as a potential diagnostic markers and drug targets. In the present study we analyzed the purely cytosolic proteome of amikacin (AK and kanamycin (KM resistant Mycobacterium tuberculosis isolates by proteomic and bioinformatic approaches. Twenty protein spots were found to have over expressed in resistant isolates and were identified. Among these Rv3208A, Rv2623, Rv1360, Rv2140c, Rv1636 and Rv2185c are six proteins with unknown functions or undefined role. Docking results showed that AK and KM binds to the conserved domain (DUF, USP-A, Luciferase, PEBP and Polyketidecyclase/dehydrase domain of these hypothetical proteins and over expression of these proteins might neutralize/modulate the effect of drug molecules. TBPred and GPS-PUP predicted cytoplasmic nature and potential pupylation sites within these identified proteins respectively. String analysis also suggested that over expressed proteins along with their interactive partners might be involved in aminoglycosides resistance. Cumulative effect of these over expressed proteins could be involved in AK and KM resistance by mitigating the toxicity, repression of drug target and neutralizing affect. These findings need further exploitation for the expansion of newer therapeutics or diagnostic markers against AK and KM resistance so that an extreme condition like XDR-TB can

  9. Cytosolic Proteome Profiling of Aminoglycosides Resistant Mycobacterium tuberculosis Clinical Isolates Using MALDI-TOF/MS.

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    Sharma, Divakar; Lata, Manju; Singh, Rananjay; Deo, Nirmala; Venkatesan, Krishnamurthy; Bisht, Deepa

    2016-01-01

    Emergence of extensively drug resistant tuberculosis (XDR-TB) is the consequence of the failure of second line TB treatment. Aminoglycosides are the important second line anti-TB drugs used to treat the multi drug resistant tuberculosis (MDR-TB). Main known mechanism of action of aminoglycosides is to inhibit the protein synthesis by inhibiting the normal functioning of ribosome. Primary target of aminoglycosides are the ribosomal RNA and its associated proteins. Various mechanisms have been proposed for aminoglycosides resistance but still some are unsolved. As proteins are involved in most of the biological processes, these act as a potential diagnostic markers and drug targets. In the present study we analyzed the purely cytosolic proteome of amikacin (AK) and kanamycin (KM) resistant Mycobacterium tuberculosis isolates by proteomic and bioinformatic approaches. Twenty protein spots were found to have over expressed in resistant isolates and were identified. Among these Rv3208A, Rv2623, Rv1360, Rv2140c, Rv1636, and Rv2185c are six proteins with unknown functions or undefined role. Docking results showed that AK and KM binds to the conserved domain (DUF, USP-A, Luciferase, PEBP and Polyketidecyclase/dehydrase domain) of these hypothetical proteins and over expression of these proteins might neutralize/modulate the effect of drug molecules. TBPred and GPS-PUP predicted cytoplasmic nature and potential pupylation sites within these identified proteins, respectively. String analysis also suggested that over expressed proteins along with their interactive partners might be involved in aminoglycosides resistance. Cumulative effect of these over expressed proteins could be involved in AK and KM resistance by mitigating the toxicity, repression of drug target and neutralizing affect. These findings need further exploitation for the expansion of newer therapeutics or diagnostic markers against AK and KM resistance so that an extreme condition like XDR-TB can be prevented.

  10. Novel Aminoglycoside Resistance Transposons and Transposon-Derived Circular Forms Detected in Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates

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    Dwibedi, Chinmay Kumar; Sjöström, Karin; Edquist, Petra; Wai, Sun Nyunt; Uhlin, Bernt Eric

    2016-01-01

    Acinetobacter baumannii has emerged as an important opportunistic pathogen equipped with a growing number of antibiotic resistance genes. Our study investigated the molecular epidemiology and antibiotic resistance features of 28 consecutive carbapenem-resistant clinical isolates of A. baumannii collected throughout Sweden in 2012 and 2013. The isolates mainly belonged to clonal complexes (CCs) with an extensive international distribution, such as CC2 (n = 16) and CC25 (n = 7). Resistance to carbapenems was related to blaOXA-23 (20 isolates), blaOXA-24/40-like (6 isolates), blaOXA-467 (1 isolate), and ISAba1-blaOXA-69 (1 isolate). Ceftazidime resistance was associated with blaPER-7 in the CC25 isolates. Two classical point mutations were responsible for resistance to quinolones in all the isolates. Isolates with high levels of resistance to aminoglycosides carried the 16S rRNA methylase armA gene. The isolates also carried a variety of genes encoding aminoglycoside-modifying enzymes. Several novel structures involved in aminoglycoside resistance were identified, including Tn6279, ΔTn6279, Ab-ST3-aadB, and different assemblies of Tn6020 and TnaphA6. Importantly, a number of circular forms related to the IS26 or ISAba125 composite transposons were detected. The frequent occurrence of these circular forms in the populations of several isolates indicates a potential role of these circular forms in the dissemination of antibiotic resistance genes. PMID:26824943

  11. Structural and molecular basis for resistance to aminoglycoside antibiotics by the adenylyltransferase ANT(2″)-Ia.

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    Cox, Georgina; Stogios, Peter J; Savchenko, Alexei; Wright, Gerard D

    2015-01-06

    The aminoglycosides are highly effective broad-spectrum antimicrobial agents. However, their efficacy is diminished due to enzyme-mediated covalent modification, which reduces affinity of the drug for the target ribosome. One of the most prevalent aminoglycoside resistance enzymes in Gram-negative pathogens is the adenylyltransferase ANT(2″)-Ia, which confers resistance to gentamicin, tobramycin, and kanamycin. Despite the importance of this enzyme in drug resistance, its structure and molecular mechanism have been elusive. This study describes the structural and mechanistic basis for adenylylation of aminoglycosides by the ANT(2″)-Ia enzyme. ANT(2″)-Ia confers resistance by magnesium-dependent transfer of a nucleoside monophosphate (AMP) to the 2″-hydroxyl of aminoglycoside substrates containing a 2-deoxystreptamine core. The catalyzed reaction follows a direct AMP transfer mechanism from ATP to the substrate antibiotic. Central to catalysis is the coordination of two Mg(2+) ions, positioning of the modifiable substrate ring, and the presence of a catalytic base (Asp86). Comparative structural analysis revealed that ANT(2″)-Ia has a two-domain structure with an N-terminal active-site architecture that is conserved among other antibiotic nucleotidyltransferases, including Lnu(A), LinB, ANT(4')-Ia, ANT(4″)-Ib, and ANT(6)-Ia. There is also similarity between the nucleotidyltransferase fold of ANT(2″)-Ia and DNA polymerase β. This similarity is consistent with evolution from a common ancestor, with the nucleotidyltransferase fold having adapted for activity against chemically distinct molecules. IMPORTANCE  : To successfully manage the threat associated with multidrug-resistant infectious diseases, innovative therapeutic strategies need to be developed. One such approach involves the enhancement or potentiation of existing antibiotics against resistant strains of bacteria. The reduction in clinical usefulness of the aminoglycosides is a particular

  12. Comprehensive study to investigate the role of various aminoglycoside resistance mechanisms in clinical isolates of Acinetobacter baumannii.

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    Sheikhalizadeh, Vajihe; Hasani, Alka; Ahangarzadeh Rezaee, Mohammad; Rahmati-Yamchi, Mohammad; Hasani, Akbar; Ghotaslou, Reza; Goli, Hamid Reza

    2017-02-01

    Therapeutic resistance towards most of the current treatment regime by Acinetobacter baumannii has reduced the prescribing antibiotic pattern and option is being re-shifted towards more toxic agents including aminoglycosides. The present investigation aimed at to study various mechanisms towards aminoglycoside non-susceptibility in clinical isolates of A. baumannii. The bacteria were subjected to genetic basis assessment for the presence of aminoglycoside modifying enzymes (AME), 16S rRNA methylase encoding genes and relative expression of AdeABC and AbeM efflux pumps in relation to their susceptibility to five aminoglycosides. When isolates were subjected to typing by repetitive extragenic palindromic (REP) PCR, isolates could be separated into thirteen definite clones. The majority of isolates (94%) were positive for AME encoding genes. Possession of ant(2')-Ia correlated with non-susceptibility towards gentamicin, amikacin, kanamycin, tobramycin; while, presence of aph(3')-VIa attributed to resistance towards amikacin, kanamycin; possession of aac(3')-Ia allied with non-susceptibility to amikacin, tobramycin and presence of aac(3')IIa correlated with kanamycin non-susceptibility. Presence of armA was detected in 34.4%, 34.2%, 29.2%, 40.3%, and 64.2% of isolates showing non-susceptibility to gentamicin, amikacin, kanamycin, tobramycin and netilmicin, respectively. No isolates were found to carry rmtB or rmtC. Amikacin non-susceptibility in comparison to other aminoglycosides correlated with over production of adeB. Overall, the results represented a definitive correlation between presence of AME encoding genes as well as armA and resistance of A. baumannii towards aminoglycosides. On the other hand, the up-regulation of AdeABC and AbeM systems was found to have only the partial role in development of aminoglycoside resistance. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All

  13. A study of gram-negative bacterial resistance to Aminoglycosides

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    Maleknejad P

    1993-05-01

    Full Text Available From hygienic and economical point of view, drug therapy and prophylaxy in infectious diseases are of great importance. After the world war II, a reduction in the efficacy of sulfonamide in the treatment of shigellosis was observed and later on it led to a survey on drug resistance and the way of its transmission. The aim of this survey, during which 100 cases of gram-negative bacteria were identified, is to study the drug resistance of this bacteria against five types of aminoglycosides by antibiotic sensitivity test (disc-diffusion. Out of 100 strains, 47% were resistant to gentamycin, 70% to kanamycin, 82% to streptomycin, 53% to tobramycin, and 8% to amikacin

  14. Chaperonin GroEL/GroES Over-Expression Promotes Aminoglycoside Resistance and Reduces Drug Susceptibilities in Escherichia coli Following Exposure to Sublethal Aminoglycoside Doses

    DEFF Research Database (Denmark)

    Goltermann, Lise; Sarusie, Menachem V; Bentin, Thomas

    2016-01-01

    Antibiotic resistance is an increasing challenge to modern healthcare. Aminoglycoside antibiotics cause translation corruption and protein misfolding and aggregation in Escherichia coli. We previously showed that chaperonin GroEL/GroES depletion and over-expression sensitize and promote short...

  15. An overview of strategies for synthetic modifications of aminoglycosides

    International Nuclear Information System (INIS)

    Aslam, M.W.

    2013-01-01

    Aminoglycosides, a family of structurally related broad-spectrum bactericidal compounds, have been used extensively for the treatment of aerobic gram-negative bacterial infections because of their rapid anti-bacterial activity, chemical stability and ability to work in combination with other drugs. However, toxic side-effects and growing bacterial resistance have narrowed the significance of aminoglycosides as antibiotics. Due to these limitations, extensive research on aminoglycosides has resulted in the development of a wide range of synthetic strategies to improve the overall characteristics of aminoglycosides. Herein, an overview of the various approaches reported in the literature to enhance binding affinity and to overcome resistance of aminoglycosides is provided. (author)

  16. Chromosomal mechanisms of aminoglycoside resistance in Pseudomonas aeruginosa isolates from cystic fibrosis patients

    DEFF Research Database (Denmark)

    Islam, S; Oh, H; Jalal, S

    2009-01-01

    pump protein MexY was determined by real-time PCR and correlated with susceptibilities to amikacin and tobramycin. The chromosomal genes mexZ, rplY, galU, PA5471 and nuoG, which were found to have a role in the gradual increase in MICs of aminoglycoside antibiotics in laboratory mutants of P....... aeruginosa, were analysed. MexY mRNA overproduction was found in 17/20 isolates collected in 1994 and 1997, and was correlated with decreased susceptibility to aminoglycosides. Alteration of the MexXY-OprM efflux system has been the main mechanism of resistance to aminoglycoside antibiotics in CF P......In total, 40 Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients were included in this study. Twenty of these were collected in 1994 and 1997, from six CF patients, and the rest were collected from different CF patients in 2000 and 2001. The relative expression of mRNA for the efflux...

  17. Novel Tn916-like elements confer aminoglycoside/macrolide co-resistance in clinical isolates of Streptococcus gallolyticus ssp. gallolyticus.

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    Kambarev, Stanimir; Pecorari, Frédéric; Corvec, Stéphane

    2018-02-09

    Streptococcus gallolyticus ssp. gallolyticus (Sgg) is a commensal bacterium and an opportunistic pathogen. In humans it has been clinically associated with the incidence of colorectal cancer (CRC) and epidemiologically recognized as an emerging cause of infective endocarditis (IE). The standard therapy of Sgg includes the administration of a penicillin in combination with an aminoglycoside. Even though penicillin-resistant isolates have still not been reported, epidemiological studies have shown that this microbe is a reservoir of multiple acquired genes, conferring resistance to tetracyclines, aminoglycosides, macrolides and glycopeptides. However, the underlying antibiotic resistance mobilome of Sgg remains poorly understood. To investigate the mobile genetic basis of antibiotic resistance in multiresistant clinical Sgg. Isolate NTS31106099 was recovered from a patient with IE and CRC at Nantes University Hospital, France and studied by Illumina WGS and comparative genomics. Molecular epidemiology of the identified mobile element(s) was performed using antibiotic susceptibility testing (AST), PCR, PFGE and WGS. Mobility was investigated by PCR and filter mating. Two novel conjugative transposons, Tn6263 and Tn6331, confer aminoglycoside/macrolide co-resistance in clinical Sgg. They display classical family Tn916/Tn1545 modular architecture and harbour an aph(3')-III→sat4→ant(6)-Ia→erm(B) multiresistance gene cluster, related to pRE25 of Enterococcus faecium. These and/or closely related elements are highly prevalent among genetically heterogeneous clinical isolates of Sgg. Previously unknown Tn916-like mobile genetic elements conferring aminoglycoside/macrolide co-resistance make Sgg, collectively with other gut Firmicutes such as enterococci and eubacteria, a potential laterally active reservoir of these antibiotic resistance determinants among the mammalian gastrointestinal microbiota. © The Author(s) 2018. Published by Oxford University Press on behalf

  18. In vitro studies with UK-18,892, a new aminoglycoside antibiotic.

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    Jevons, S; Cheeseman, H E; Brammer, K W

    1978-09-01

    The antibacterial activity of UK-18,892, a new semisynthetic aminoglycoside, was examined against aminoglycoside-susceptible and aminoglycoside-resistant clinical isolates of gram-negative bacilli and Staphylococcus aureus. UK-18,892 had a similar degree of activity to those of amikacin and kanamycin A against aminoglycoside-susceptible bacteria but was less potent than gentamicin against all isolates except Providencia spp. UK-18,892 was highly active against aminoglycoside-resistant bacteria, inhibiting 93% of the 268 isolates examined at 12.5 mug/ml. Amikacin was similarly active, whereas gentamicin inhibited only 14% of these isolates at 12.5 mug/ml.

  19. Characterization of resistance to tetracyclines and aminoglycosides of sheep mastitis pathogens: study of the effect of gene content on resistance.

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    Lollai, S A; Ziccheddu, M; Duprè, I; Piras, D

    2016-10-01

    Mastitis causes economic losses and antimicrobials are frequently used for mastitis treatment. Antimicrobial resistance surveys are still rare in the ovine field and characterization of strains is important in order to acquire information about resistance and for optimization of therapy. Bacterial pathogens recovered in milk samples from mastitis-affected ewes were characterized for resistance to tetracyclines and aminoglycosides, members of which are frequently used antimicrobials in small ruminants. A total of 185 strains of staphylococci, streptococci, and enterococci, common mastitis pathogens, were tested for minimal inhibitory concentration (MIC) to tetracycline, doxycycline, minocycline, gentamicin, kanamycin, streptomycin, and for resistance genes by PCR. Effects of different tet genes arrangements on MICs were also investigated. Staphylococci expressed the lowest MIC for tetracycline and tet(K) was the most common gene recovered; tet(M) and tet(O) were also found. Gene content was shown to influence the tetracycline MIC values. Enterococci and streptococci showed higher MICs to tetracyclines and nonsusceptible strains always harboured at least one ribosomal protection gene (MIC above 8 μg ml(-1) ). Streptococci often harboured two or more tet determinants. As regards the resistance to aminoglycosides, staphylococci showed the lowest gentamicin and kanamycin median MIC along with streptomycin high level resistant (HLR) strains (MIC >1024 μg ml(-1) ) all harbouring str gene. The resistance determinant aac(6')-Ie-aph(2″)-Ia was present in few strains. Streptococci were basically nonsusceptible to aminoglycosides but neither HLR isolates nor resistance genes were detected. Enterococci revealed the highest MICs for gentamicin; two str harbouring isolates were shown to be HLR to streptomycin. Evidence was obtained for the circulation of antimicrobial-resistant strains and genes in sheep dairy farming. Tetracycline MIC of 64 μg ml(-1) and high

  20. Aminoglycoside-resistant Aeromonas hydrophila as part of a polymicrobial infection following a traumatic fall into freshwater.

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    Shak, Joshua R; Whitaker, Jennifer A; Ribner, Bruce S; Burd, Eileen M

    2011-03-01

    Amikacin is a first-line treatment for Aeromonas infection due to high efficacy. There are few reports of aminoglycoside-resistant Aeromonas spp. We report a soft tissue infection containing multiple pathogens, including a strain of Aeromonas hydrophila resistant to amikacin, tobramycin, and multiple cephalosporins.

  1. Aminoglycoside-Resistant Aeromonas hydrophila as Part of a Polymicrobial Infection following a Traumatic Fall into Freshwater▿

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    Shak, Joshua R.; Whitaker, Jennifer A.; Ribner, Bruce S.; Burd, Eileen M.

    2011-01-01

    Amikacin is a first-line treatment for Aeromonas infection due to high efficacy. There are few reports of aminoglycoside-resistant Aeromonas spp. We report a soft tissue infection containing multiple pathogens, including a strain of Aeromonas hydrophila resistant to amikacin, tobramycin, and multiple cephalosporins. PMID:21209173

  2. Clonal origin of aminoglycoside-resistant Citrobacter freundii isolates in a Danish county

    DEFF Research Database (Denmark)

    Norskov-Lauritsen, N.; Sandvang, Dorthe; Hedegaard, J.

    2001-01-01

    During 1997, attention was drawn to an increased frequency of aminoglycoside-resistant Citrobacter freundii in a Danish county, when a total of 24 resistant C. freundii isolates was detected. In this study, 15 such isolates were typed by pulsed-field gel electrophoresis, riboprinting and partial...... with a dihydrofolate reductase gene in a class I integron. The source of the strain remains unresolved. Representative isolates were obtained from various specimens from hospitals and general practice throughout the county, with no evidence of patient-to-patient transmission....

  3. Molecular genetics of Mycobacterium tuberculosis resistant to aminoglycosides and cyclic peptide testing by MTBDRsl in Armenia

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    Hasmik Margaryan

    2016-01-01

    Conclusion: Isolates with rrs structural gene mutations were cross-resistant to streptomycin, KAN, CAP, and AMK. Detection of the A1401G mutation appeared to be 100% specific for the detection of resistance to KAN and AMK. Being the first assessment, these data establish the presence of phenotypic drug-resistant and extensively drug-resistant strains using molecular profiling and are helpful in understanding aminoglycoside resistance on a molecular level.

  4. Antibiotic stress-induced modulation of the endoribonucleolytic activity of RNase III and RNase G confers resistance to aminoglycoside antibiotics in Escherichia coli.

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    Song, Wooseok; Kim, Yong-Hak; Sim, Se-Hoon; Hwang, Soonhye; Lee, Jung-Hyun; Lee, Younghoon; Bae, Jeehyeon; Hwang, Jihwan; Lee, Kangseok

    2014-04-01

    Here, we report a resistance mechanism that is induced through the modulation of 16S ribosomal RNA (rRNA) processing on the exposure of Escherichia coli cells to aminoglycoside antibiotics. We observed decreased expression levels of RNase G associated with increased RNase III activity on rng mRNA in a subgroup of E. coli isolates that transiently acquired resistance to low levels of kanamycin or streptomycin. Analyses of 16S rRNA from the aminoglycoside-resistant E. coli cells, in addition to mutagenesis studies, demonstrated that the accumulation of 16S rRNA precursors containing 3-8 extra nucleotides at the 5' terminus, which results from incomplete processing by RNase G, is responsible for the observed aminoglycoside resistance. Chemical protection, mass spectrometry analysis and cell-free translation assays revealed that the ribosomes from rng-deleted E. coli have decreased binding capacity for, and diminished sensitivity to, streptomycin and neomycin, compared with wild-type cells. It was observed that the deletion of rng had similar effects in Salmonella enterica serovar Typhimurium strain SL1344. Our findings suggest that modulation of the endoribonucleolytic activity of RNase III and RNase G constitutes a previously uncharacterized regulatory pathway for adaptive resistance in E. coli and related gram-negative bacteria to aminoglycoside antibiotics.

  5. UK-18,892: resistance to modification by aminoglycoside-inactivating enzymes.

    Science.gov (United States)

    Andrews, R J; Brammer, K W; Cheeseman, H E; Jevons, S

    1978-12-01

    UK-18,892, a new semisynthetic aminoglycoside, was active against bacteria possessing aminoglycoside-inactivating enzymes, with the exception of some known to possess AAC(6') or AAD(4') enzymes. This activity has been rationalized by using cell-free extracts of bacteria containing known inactivating enzymes, where it was shown that UK-18,892 was not a substrate for the APH(3'), AAD(2''), AAC(3), and AAC(2') enzymes. It was also demonstrated that UK-18,892 protected mice against lethal infections caused by organisms possessing aminoglycoside-inactivating enzymes.

  6. Structure of the phosphotransferase domain of the bifunctional aminoglycoside-resistance enzyme AAC(6')-Ie-APH(2'')-Ia.

    Science.gov (United States)

    Smith, Clyde A; Toth, Marta; Bhattacharya, Monolekha; Frase, Hilary; Vakulenko, Sergei B

    2014-06-01

    The bifunctional acetyltransferase(6')-Ie-phosphotransferase(2'')-Ia [AAC(6')-Ie-APH(2'')-Ia] is the most important aminoglycoside-resistance enzyme in Gram-positive bacteria, conferring resistance to almost all known aminoglycoside antibiotics in clinical use. Owing to its importance, this enzyme has been the focus of intensive research since its isolation in the mid-1980s but, despite much effort, structural details of AAC(6')-Ie-APH(2'')-Ia have remained elusive. The structure of the Mg2GDP complex of the APH(2'')-Ia domain of the bifunctional enzyme has now been determined at 2.3 Å resolution. The structure of APH(2'')-Ia is reminiscent of the structures of other aminoglycoside phosphotransferases, having a two-domain architecture with the nucleotide-binding site located at the junction of the two domains. Unlike the previously characterized APH(2'')-IIa and APH(2'')-IVa enzymes, which are capable of utilizing both ATP and GTP as the phosphate donors, APH(2'')-Ia uses GTP exclusively in the phosphorylation of the aminoglycoside antibiotics, and in this regard closely resembles the GTP-dependent APH(2'')-IIIa enzyme. In APH(2'')-Ia this GTP selectivity is governed by the presence of a `gatekeeper' residue, Tyr100, the side chain of which projects into the active site and effectively blocks access to the adenine-binding template. Mutation of this tyrosine residue to a less bulky phenylalanine provides better access for ATP to the NTP-binding template and converts APH(2'')-Ia into a dual-specificity enzyme.

  7. Dissemination of Genes Encoding Aminoglycoside-Modifying Enzymes and armA Among Enterobacteriaceae Isolates in Northwest Iran.

    Science.gov (United States)

    Ghotaslou, Reza; Yeganeh Sefidan, Fatemeh; Akhi, Mohammad Taghi; Asgharzadeh, Mohammad; Mohammadzadeh Asl, Yalda

    2017-10-01

    Enzymatic inactivation is one of the most important mechanisms of resistance to aminoglycosides. The aim of this study was to investigate the prevalence of armA and diversity of the genes encoding aminoglycoside-modifying enzymes (AMEs) and their associations with resistance phenotypes in Enterobacteriaceae isolates. Three hundred and seven Enterobacteriaceae isolates were collected from five hospitals in northwest Iran. The disk diffusion method for amikacin, gentamicin, tobramycin, kanamycin, and streptomycin, as well as the minimum inhibitory concentration for amikacin, gentamicin, tobramycin, and kanamycin were done for susceptibility testing. Thirteen AME genes and armA methylase were screened using the PCR and sequencing assays. Two hundred and twenty (71.7%) of isolates were resistant to aminoglycosides and 155 (70.5%) of them were positive for aminoglycoside resistance genes. The most prevalent AME genes were ant(3″)-Ia and aph(3″)-Ib with the frequency 35.9% and 30.5%, respectively. Also, 21 (9.5%) of resistant isolates were positive for armA methylase gene. The prevalence of resistance to aminoglycoside is high and AME genes frequently are disseminated in Enterobacteriaceae isolates. There is an association between phenotypic resistance and the presence of some aminoglycoside genes.

  8. Application of protein typing in molecular epidemiological investigation of nosocomial infection outbreak of aminoglycoside-resistant Pseudomonas aeruginosa.

    Science.gov (United States)

    Song, Min; Tang, Min; Ding, Yinghuan; Wu, Zecai; Xiang, Chengyu; Yang, Kui; Zhang, Zhang; Li, Baolin; Deng, Zhenghua; Liu, Jinbo

    2017-12-16

    Pseudomonas aeruginosan has emerged as an important pathogen elated to serious infections and nosocomial outbreaks worldwide. This study was conducted to understand the prevalence of aminoglycoside (AMG)-resistant P. aeruginosa in our hospital and to provide a scientific basis for control measures against nosocomial infections. Eighty-two strains of P. aeruginosa were isolated from clinical departments and divided into AMG-resistant strains and AMG-sensitive strains based on susceptibility test results. AMG-resistant strains were typed by drug resistance gene typing (DRGT) and protein typing. Five kinds of aminoglycoside-modifying enzyme (AME) genes were detected in the AMG-resistant group. AMG-resistant P. aeruginosa strains were classified into three types and six subtypes by DRGT. Four protein peaks, namely, 9900.02, 7600.04, 9101.25 and 10,372.87 Da, were significantly and differentially expressed between the two groups. AMG-resistant P. aeruginosa strains were also categorised into three types and six subtypes at the distance level of 10 by protein typing. AMG-resistant P. aeruginosa was cloned spread in our hospital; the timely implementation of nosocomial infection prevention and control strategies were needed in preventing outbreaks and epidemic of AMG-resistant P. aeruginosa. SELDI-TOF MS technology can be used for bacterial typing, which provides a new method of clinical epidemiological survey and nosocomial infection control.

  9. Synergy of aminoglycoside antibiotics by 3-Benzylchroman derivatives from the Chinese drug Caesalpinia sappan against clinical methicillin-resistant Staphylococcus aureus (MRSA).

    Science.gov (United States)

    Zuo, G Y; Han, Z Q; Hao, X Y; Han, J; Li, Z S; Wang, G C

    2014-06-15

    The in vitro antimicrobial activities of three 3-Benzylchroman derivatives, i.e. Brazilin (1), Brazilein (2) and Sappanone B (3) from Caesalpinia sappan L. (Leguminosae) were assayed, which mainly dealt with synergistic evaluation of aminoglycoside and other type of antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) by the three compounds through the Chequerboard and Time-kill curve methods. The results showed that Compounds 1-3 alone exhibited moderate to weak activity against methicillin-susceptible S. aureus (MSSA) and other standard strains by MICs/MBCs ranged from 32/64 to >1024/>1024 μg/ml, with the order of activity as 1>2>3. Chequerboard method showed significant anti-MRSA synergy of 1/Aminoglycosides (Gentamicin, Amikacin, Etimicin and Streptomycin) combinations with (FICIs)50 at 0.375-0.5. The combined (MICs)50 values (μg/ml) reduced from 32-128/16-64 to 4-8/4-16, respectively. The percent of reduction by MICs ranged from 50% to 87.5%, with a maximum of 93.8% (1/16 of the alone MIC). Combinations of 2 and 3 with Aminoglycosides and the other antibiotics showed less potency of synergy. The dynamic Time-killing experiment further demonstrated that the combinations of 1/aminoglycoside were synergistically bactericidal against MRSA. The anti-MRSA synergy results of the bacteriostatic (Chequerboard method) and bactericidal (time-kill method) efficiencies of 1/Aminoglycoside combinations was in good consistency, which made the resistance reversed by CLSI guidelines. We concluded that the 3-Benzylchroman derivative Brazilin (1) showed in vitro synergy of bactericidal activities against MRSA when combined with Aminoglycosides, which might be beneficial for combinatory therapy of MRSA infection. Copyright © 2014. Published by Elsevier GmbH.

  10. Association of the novel aminoglycoside resistance determinant RmtF with NDM carbapenemase in Enterobacteriaceae isolated in India and the UK

    DEFF Research Database (Denmark)

    Hidalgo, Laura; Hopkins, Katie L; Gutierrez, Belen

    2013-01-01

    16S rRNA methyltransferases are an emerging mechanism conferring high-level resistance to clinically relevant aminoglycosides and have been associated with important mechanisms such as NDM-1. We sought genes encoding these enzymes in isolates highly resistant (MIC >200 mg/L) to gentamicin and ami...

  11. Environmental and genetic factors affecting mutability to aminoglycoside antibiotics among Escherichia coli K12 strains

    Directory of Open Access Journals (Sweden)

    Monteiro A.C.M.

    2003-01-01

    Full Text Available Environmental and genetic factors affecting the in vitro spontaneous mutation frequencies to aminoglycoside resistance in Escherichia coli K12 were investigated. Spontaneous mutation frequencies to kanamycin resistance were at least 100 fold higher on modified Luria agar (L2 plates, when compared to results obtained in experiments carried out with Nutrient agar (NA plates. In contrast to rifampincin, the increased mutability to kanamycin resistance could not be attributed to a mutator phenotype expressed by DNA repair defective strains. Kanamycin mutant selection windows and mutant preventive concentrations on L2 plates were at least fourfold higher than on NA plates, further demonstrating the role of growth medium composition on the mutability to aminoglycosides. Mutability to kanamycin resistance was increased following addition of sorbitol, suggesting that osmolarity is involved on the spontaneous mutability of E. coli K12 strains to aminoglycosides. The spontaneous mutation rates to kanamycin resistance on both L2 and NA plates were strictly associated with the selective antibiotic concentrations. Moreover, mutants selected at different antibiotic concentrations expressed heterogeneous resistance levels to kanamycin and most of them expressing multiple resistance to all tested aminoglycoside antibiotics (gentamicin, neomycin, amykacin and tobramycin. These results will contribute to a better understanding of the complex nature of aminoglycoside resistance and the emergence of spontaneous resistant mutants among E. coli K12 strains.

  12. DNA-Aptamers Binding Aminoglycoside Antibiotics

    Directory of Open Access Journals (Sweden)

    Nadia Nikolaus

    2014-02-01

    Full Text Available Aptamers are short, single stranded DNA or RNA oligonucleotides that are able to bind specifically and with high affinity to their non-nucleic acid target molecules. This binding reaction enables their application as biorecognition elements in biosensors and assays. As antibiotic residues pose a problem contributing to the emergence of antibiotic-resistant pathogens and thereby reducing the effectiveness of the drug to fight human infections, we selected aptamers targeted against the aminoglycoside antibiotic kanamycin A with the aim of constructing a robust and functional assay that can be used for water analysis. With this work we show that aptamers that were derived from a Capture-SELEX procedure targeting against kanamycin A also display binding to related aminoglycoside antibiotics. The binding patterns differ among all tested aptamers so that there are highly substance specific aptamers and more group specific aptamers binding to a different variety of aminoglycoside antibiotics. Also the region of the aminoglycoside antibiotics responsible for aptamer binding can be estimated. Affinities of the different aptamers for their target substance, kanamycin A, are measured with different approaches and are in the micromolar range. Finally, the proof of principle of an assay for detection of kanamycin A in a real water sample is given.

  13. Triclosan-Induced Aminoglycoside-Tolerant Listeria monocytogenes Isolates Can Appear as Small-Colony Variants

    DEFF Research Database (Denmark)

    Kastbjerg, Vicky Gaedt; Hein-Kristensen, Line; Gram, Lone

    2014-01-01

    Exposure of the human food-borne pathogen Listeria monocytogenes to sublethal concentrations of triclosan can cause resistance to several aminoglycosides. Aminoglycoside-resistant isolates exhibit two colony morphologies: normal-size and pinpoint colonies. The purposes of the present study were...... to characterize the small colonies of L. monocytogenes and to determine if specific genetic changes could explain the triclosan-induced aminoglycoside resistance in both pinpoint and normal-size isolates. Isolates from the pinpoint colonies grew poorly under aerated conditions, but growth was restored by addition......I and that exposure to triclosan can cause resistance to antibiotics that enters the cell via active transport. Further studies are needed to elucidate if L. monocytogenes pinpoint isolates could have any clinical impact, e.g., in persistent infections....

  14. Structural Analysis of the Tobramycin and Gentamicin Clinical Resistome Reveals Limitations for Next-generation Aminoglycoside Design.

    Science.gov (United States)

    Bassenden, Angelia V; Rodionov, Dmitry; Shi, Kun; Berghuis, Albert M

    2016-05-20

    Widespread use and misuse of antibiotics has allowed for the selection of resistant bacteria capable of avoiding the effects of antibiotics. The primary mechanism for resistance to aminoglycosides, a broad-spectrum class of antibiotics, is through covalent enzymatic modification of the drug, waning their bactericidal effect. Tobramycin and gentamicin are two medically important aminoglycosides targeted by several different resistance factors, including aminoglycoside 2″-nucleotidyltransferase [ANT(2″)], the primary cause of aminoglycoside resistance in North America. We describe here two crystal structures of ANT(2″), each in complex with AMPCPP, Mn(2+), and either tobramycin or gentamicin. Together these structures outline ANT(2″)'s specificity for clinically used substrates. Importantly, these structures complete our structural knowledge for the set of enzymes that most frequently confer clinically observed resistance to tobramycin and gentamicin. Comparison of tobramycin and gentamicin binding to enzymes in this resistome, as well as to the intended target, the bacterial ribosome, reveals surprising diversity in observed drug-target interactions. Analysis of the diverse binding modes informs that there are limited opportunities for developing aminoglycoside analogs capable of evading resistance.

  15. Pediatric fecal microbiota harbor diverse and novel antibiotic resistance genes.

    Directory of Open Access Journals (Sweden)

    Aimée M Moore

    Full Text Available Emerging antibiotic resistance threatens human health. Gut microbes are an epidemiologically important reservoir of resistance genes (resistome, yet prior studies indicate that the true diversity of gut-associated resistomes has been underestimated. To deeply characterize the pediatric gut-associated resistome, we created metagenomic recombinant libraries in an Escherichia coli host using fecal DNA from 22 healthy infants and children (most without recent antibiotic exposure, and performed functional selections for resistance to 18 antibiotics from eight drug classes. Resistance-conferring DNA fragments were sequenced (Illumina HiSeq 2000, and reads assembled and annotated with the PARFuMS computational pipeline. Resistance to 14 of the 18 antibiotics was found in stools of infants and children. Recovered genes included chloramphenicol acetyltransferases, drug-resistant dihydrofolate reductases, rRNA methyltransferases, transcriptional regulators, multidrug efflux pumps, and every major class of beta-lactamase, aminoglycoside-modifying enzyme, and tetracycline resistance protein. Many resistance-conferring sequences were mobilizable; some had low identity to any known organism, emphasizing cryptic organisms as potentially important resistance reservoirs. We functionally confirmed three novel resistance genes, including a 16S rRNA methylase conferring aminoglycoside resistance, and two tetracycline-resistance proteins nearly identical to a bifidobacterial MFS transporter (B. longum s. longum JDM301. We provide the first report to our knowledge of resistance to folate-synthesis inhibitors conferred by a predicted Nudix hydrolase (part of the folate synthesis pathway. This functional metagenomic survey of gut-associated resistomes, the largest of its kind to date, demonstrates that fecal resistomes of healthy children are far more diverse than previously suspected, that clinically relevant resistance genes are present even without recent selective

  16. Nordihydroguaiaretic acid enhances the activities of aminoglycosides against methicillin- sensitive and resistant Staphylococcus aureus in vitro and in vivo.

    Science.gov (United States)

    Cunningham-Oakes, Edward; Soren, Odel; Moussa, Caroline; Rathor, Getika; Liu, Yingjun; Coates, Anthony; Hu, Yanmin

    2015-01-01

    Infections caused by methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) are prevalent. MRSA infections are difficult to treat and there are no new classes of antibiotics produced to the market to treat infections caused by the resistant bacteria. Therefore, using antibiotic enhancers to rescue existing classes of antibiotics is an attractive strategy. Nordihydroguaiaretic acid (NDGA) is an antioxidant compound found in extracts from plant Larrea Tridentata. It exhibits antimicrobial activity and may target bacterial cell membrane. Combination efficacies of NDGA with many classes of antibiotics were examined by chequerboard method against 200 clinical isolates of MRSA and MSSA. NDGA in combination with gentamicin, neomycin, and tobramycin was examined by time-kill assays. The synergistic combinations of NDGA and aminoglycosides were tested in vivo using a murine skin infection model. Calculations of the fractional inhibitory concentration index (FICI) showed that NDGA when combined with gentamicin, neomycin, or tobramycin displayed synergistic activities in more than 97% of MSSA and MRSA, respectively. Time kill analysis demonstrated that NDGA significantly augmented the activities of these aminoglycosides against MRSA and MSSA in vitro and in murine skin infection model. The enhanced activity of NDGA resides on its ability to damage bacterial cell membrane leading to accumulation of the antibiotics inside bacterial cells. We demonstrated that NDGA strongly revived the therapeutic potencies of aminoglycosides in vitro and in vivo. This combinational strategy could contribute major clinical implications to treat antibiotic resistant bacterial infections.

  17. Structure of the phosphotransferase domain of the bifunctional aminoglycoside-resistance enzyme AAC(6′)-Ie-APH(2′′)-Ia

    Science.gov (United States)

    Smith, Clyde A.; Toth, Marta; Bhattacharya, Monolekha; Frase, Hilary; Vakulenko, Sergei B.

    2014-01-01

    The bifunctional acetyltransferase(6′)-Ie-phosphotransfer­ase(2′′)-Ia [AAC(6′)-Ie-APH(2′′)-Ia] is the most important aminoglycoside-resistance enzyme in Gram-positive bacteria, conferring resistance to almost all known aminoglycoside antibiotics in clinical use. Owing to its importance, this enzyme has been the focus of intensive research since its isolation in the mid-1980s but, despite much effort, structural details of AAC(6′)-Ie-APH(2′′)-Ia have remained elusive. The structure of the Mg2GDP complex of the APH(2′′)-Ia domain of the bifunctional enzyme has now been determined at 2.3 Å resolution. The structure of APH(2′′)-Ia is reminiscent of the structures of other aminoglycoside phosphotransferases, having a two-domain architecture with the nucleotide-binding site located at the junction of the two domains. Unlike the previously characterized APH(2′′)-IIa and APH(2′′)-IVa enzymes, which are capable of utilizing both ATP and GTP as the phosphate donors, APH(2′′)-Ia uses GTP exclusively in the phosphorylation of the aminoglycoside antibiotics, and in this regard closely resembles the GTP-dependent APH(2′′)-IIIa enzyme. In APH(2′′)-Ia this GTP selectivity is governed by the presence of a ‘gatekeeper’ residue, Tyr100, the side chain of which projects into the active site and effectively blocks access to the adenine-binding template. Mutation of this tyrosine residue to a less bulky phenylalanine provides better access for ATP to the NTP-binding template and converts APH(2′′)-Ia into a dual-specificity enzyme. PMID:24914967

  18. Detection and characterization of multidrug-resistant enterobacteria bearing aminoglycoside-modifying gene in a university hospital at Rio de Janeiro, Brazil, along three decades.

    Science.gov (United States)

    Dias-Gonçalves, Verônica; Bohrer-Lengruber, Françoise; Oliveira-Fonseca, Bianca; Santos-Pereira, Renata Meirelles; Barbosa de Melo, Luis Dione; Gazos-Lopes, Ulisses; Ribeiro-Bello, Alexandre; Adler-Pereira, José Augusto

    2015-01-01

    Multidrug-resistant Enterobacteriaceae, particularly those resistant to gentamicin, have become one of the most important causes of nosocomial infections. We sought to investigate the presence of genes conferring resistance to aminoglycosides, specially to gentamicin, in Klebsiella pneumoniae and Escherichia coli multidrug-resistant strains isolated from different clinical materials among patients hospitalized in a university hospital in Rio de Janeiro, Brazil. Ten colonization strains and 20 infection strains were evaluated during three decades (1980 to 2010) using selective media containing 8 µg/ml of gentamicin. Thirty strains were tested for antimicrobial susceptibility. Twenty two strains were subjected to plasmid DNA extraction and 12 to hybridization assays using as probe a 1.9 kb plasmid DNA fragment from one of the K. pneumoniae strains isolated from faecal samples. This fragment was sequenced and assigned to the GQ422439 GenBank record. PCR was also performed using oligonucleotides designed for aminoglycoside-modifying enzymes. An accC2 acetylase, besides transposons and insertion sequences, were evidenced. Twenty-four (80%) of the isolates were positive for the aacC2 gene in agreement with antibiotic susceptibility testing profiles, indicating the persistent presence of this gene throughout the three decades. We detected high molecular weight plasmids in 54,5% of the strains. Of the tested strains, 91% showed positive signal in the hybridization assays. A gene codifying for one specific aminoglycoside-modifying enzyme was detected all throughout the three decades. Our data back the adoption of preventive measures, such as a more conscious use of antimicrobial agents in hospital environments, which can contribute to control the dissemination of microorganisms harboring resistance gene plasmids.

  19. Intrinsic resistance to aminoglycosides in Enterococcus faecium is conferred by the 16S rRNA m5C1404-specific methyltransferase EfmM

    DEFF Research Database (Denmark)

    Galimand, Marc; Schmitt, Emmanuelle; Panvert, Michel

    2011-01-01

    methyltransferase, as well as by the previously characterized aac(6')-Ii that encodes a 6'-N-aminoglycoside acetyltransferase. Inactivation of efmM in E. faecium increases susceptibility to the aminoglycosides kanamycin and tobramycin, and, conversely, expression of a recombinant version of efmM in Escherichia coli...... confers resistance to these drugs. The EfmM protein shows significant sequence similarity to E. coli RsmF (previously called YebU), which is a 5-methylcytidine (m(5)C) methyltransferase modifying 16S rRNA nucleotide C1407. The target for EfmM is shown by mass spectrometry to be a neighboring 16S r...

  20. Sulfonamide-Based Inhibitors of Aminoglycoside Acetyltransferase Eis Abolish Resistance to Kanamycin in Mycobacterium tuberculosis

    Energy Technology Data Exchange (ETDEWEB)

    Garzan, Atefeh; Willby, Melisa J.; Green, Keith D.; Gajadeera, Chathurada S.; Hou, Caixia; Tsodikov, Oleg V.; Posey, James E.; Garneau-Tsodikova, Sylvie

    2016-12-08

    A two-drug combination therapy where one drug targets an offending cell and the other targets a resistance mechanism to the first drug is a time-tested, yet underexploited approach to combat or prevent drug resistance. By high-throughput screening, we identified a sulfonamide scaffold that served as a pharmacophore to generate inhibitors of Mycobacterium tuberculosis acetyltransferase Eis, whose upregulation causes resistance to the aminoglycoside (AG) antibiotic kanamycin A (KAN) in Mycobacterium tuberculosis. Rational systematic derivatization of this scaffold to maximize Eis inhibition and abolish the Eis-mediated KAN resistance of M. tuberculosis yielded several highly potent agents. A crystal structure of Eis in complex with one of the most potent inhibitors revealed that the inhibitor bound Eis in the AG-binding pocket held by a conformationally malleable region of Eis (residues 28–37) bearing key hydrophobic residues. These Eis inhibitors are promising leads for preclinical development of innovative AG combination therapies against resistant TB.

  1. Evaluating the Frequency of aac(6')-IIa, ant(2″)-I, intl1, and intl2 Genes in Aminoglycosides Resistant Klebsiella pneumoniae Isolates Obtained from Hospitalized Patients in Yazd, Iran.

    Science.gov (United States)

    Mokhtari, Hesam; Eslami, Gilda; Zandi, Hengameh; Dehghan-Banadkouki, Amin; Vakili, Mahmood

    2018-01-01

    Klebsiella pneumoniae (K. pneumoniae) is an opportunistic pathogen that could be resistant to many antimicrobial agents. Resistance genes can be carried among gram-negative bacteria by integrons. Enzymatic inactivation is the most important mechanism of resistance to aminoglycosides. In this study, the frequencies of two important resistance gene aac(6')-II a and ant(2″)-I, and genes coding integrase I and II, in K. pneumoniae isolates resistant to aminoglycosides were evaluated. In this cross-sectional study, an attempt was made to assess the antibiotic susceptibility of 130 K. pneumoniae isolates obtained from different samples of patients hospitalized in training hospitals of Yazd evaluated by disk diffusion method. The frequencies of aac(6')-II a, ant(2″)-I, intl1 , and intl2 genes were determined by PCR method. Data were analyzed by chi-square method using SPSS software (Ver. 16). our results showed that resistance to gentamicin, tobramycin, kanamycin, and amikacin were 34.6, 33.8, 43.8, and 14.6%, respectively. The frequencies of aac (6')-II a, ant(2″)-I, intl1 , and intl2 genes were 44.6, 27.7, 90, and 0%, respectively. This study showed there are high frequencies of genes coding aminoglycosides resistance in K. pneumoniae isolates. Hence, it is very important to monitor and inhibit the spread of antibiotic resistance genes.

  2. Effect of mutations in the A site of 16 S rRNA on aminoglycoside antibiotic-ribosome interaction

    DEFF Research Database (Denmark)

    Recht, M I; Douthwaite, S; Dahlquist, K D

    1999-01-01

    antibiotics, which also interact with this region of rRNA. Mutations of certain nucleotides in rRNA reduce aminoglycoside binding affinity, as previously demonstrated using a model RNA oligonucleotide system. Here, predictions from the oligonucleotide system were tested in the ribosome by mutation...... for the aminoglycoside paromomycin, whereas no discernible reduction in affinity was observed with 1406 mutant ribosomes. These data are consistent with prior NMR structural determination of aminoglycoside interaction with the decoding region, and further our understanding of how aminoglycoside resistance can...

  3. Molecular detection of aminoglycoside-modifying enzyme genes in Acinetobacter baumannii clinical isolates.

    Science.gov (United States)

    Heidary, Mohsen; Salimi Chirani, Alireza; Khoshnood, Saeed; Eslami, Gita; Atyabi, Seyyed Mohammad; Nazem, Habibollah; Fazilati, Mohammad; Hashemi, Ali; Soleimani, Saleh

    2017-06-01

    Acinetobacter baumannii is a major opportunistic pathogen in healthcare settings worldwide. In Iran, there are only few reports on the prevalence of aminoglycoside resistance genes among A. baumannii isolates. The aim of this study was to investigate the existence of aminoglycoside-modifying enzyme (AME) genes from A. baumannii strains collected at a university teaching hospital in Iran. One hundred A. baumannii strains were collected between 2014 and 2015 from hospitalized patients at Loghman Hakim Hospital, Tehran, Iran. Antimicrobial susceptibility was determined by disk diffusion method according to the Clinical and Laboratory Standards Institute recommendations. The DNA was extracted using a kit obtained from Bioneer Co. (Korea) and was used as a template for polymerase chain reaction. The most active antimicrobial agent against these strains was colistin. The rate of extended-spectrum cephalosporin resistance was 97%. The aadA1, aadB, aac(6')-Ib, and aac(3)-IIa genes were found in 85%, 77%, 72%, and 68% of A. baumannii isolates, respectively. This study showed a high prevalence rate of AME genes in A. baumannii. This prevalence rate has explained that further aminoglycoside resistance genes may have role in the resistance of clinical isolates of A. baumannii. Therefore, control and treatment of serious infections caused by this opportunistic pathogen should be given more consideration.

  4. Structure of AadA from Salmonella enterica: a monomeric aminoglycoside (3′′)(9) adenyltransferase

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang [Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala (Sweden); Näsvall, Joakim [Uppsala University, Biomedical Center, Box 582, SE-751 23 Uppsala (Sweden); Wu, Shiying [Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala (Sweden); Andersson, Dan I. [Uppsala University, Biomedical Center, Box 582, SE-751 23 Uppsala (Sweden); Selmer, Maria, E-mail: maria.selmer@icm.uu.se [Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala (Sweden)

    2015-10-31

    The crystal structure of the aminoglycoside-adenylating enzyme AadA is reported together with functional experiments providing insights into its oligomeric state, ligand binding and catalysis. Aminoglycoside resistance is commonly conferred by enzymatic modification of drugs by aminoglycoside-modifying enzymes such as aminoglycoside nucleotidyltransferases (ANTs). Here, the first crystal structure of an ANT(3′′)(9) adenyltransferase, AadA from Salmonella enterica, is presented. AadA catalyses the magnesium-dependent transfer of adenosine monophosphate from ATP to the two chemically dissimilar drugs streptomycin and spectinomycin. The structure was solved using selenium SAD phasing and refined to 2.5 Å resolution. AadA consists of a nucleotidyltransferase domain and an α-helical bundle domain. AadA crystallizes as a monomer and is a monomer in solution as confirmed by small-angle X-ray scattering, in contrast to structurally similar homodimeric adenylating enzymes such as kanamycin nucleotidyltransferase. Isothermal titration calorimetry experiments show that ATP binding has to occur before binding of the aminoglycoside substrate, and structure analysis suggests that ATP binding repositions the two domains for aminoglycoside binding in the interdomain cleft. Candidate residues for ligand binding and catalysis were subjected to site-directed mutagenesis. In vivo resistance and in vitro binding assays support the role of Glu87 as the catalytic base in adenylation, while Arg192 and Lys205 are shown to be critical for ATP binding.

  5. Evolution of the Pseudomonas aeruginosa Aminoglycoside Mutational Resistome In Vitro and in the Cystic Fibrosis Setting.

    Science.gov (United States)

    López-Causapé, Carla; Rubio, Rosa; Cabot, Gabriel; Oliver, Antonio

    2018-04-01

    Inhaled administration of high doses of aminoglycosides is a key maintenance treatment of Pseudomonas aeruginosa chronic respiratory infections in cystic fibrosis (CF). We analyzed the dynamics and mechanisms of stepwise high-level tobramycin resistance development in vitro and compared the results with those of isogenic pairs of susceptible and resistant clinical isolates. Resistance development correlated with fusA1 mutations in vitro and in vivo. pmrB mutations, conferring polymyxin resistance, were also frequently selected in vitro In contrast, mutational overexpression of MexXY, a hallmark of aminoglycoside resistance in CF, was not observed in in vitro evolution experiments. Copyright © 2018 American Society for Microbiology.

  6. In vitro activity of aminoglycosides against clinical isolates of Acinetobacter baumannii complex and other nonfermentative Gram-negative bacilli causing healthcare-associated bloodstream infections in Taiwan.

    Science.gov (United States)

    Liu, Jyh-You; Wang, Fu-Der; Ho, Mao-Wang; Lee, Chen-Hsiang; Liu, Jien-Wei; Wang, Jann-Tay; Sheng, Wang-Huei; Hseuh, Po-Ren; Chang, Shan-Chwen

    2016-12-01

    Aminoglycosides possess in vitro activity against aerobic and facultative Gram-negative bacilli. However, nationwide surveillance on susceptibility data of Acinetobacter baumannii complex and Pseudomonas aeruginosa to aminoglycosides was limited, and aminoglycoside resistance has emerged in the past decade. We study the in vitro susceptibility of A. baumannii complex and other nonfermentative Gram-negative bacilli (NFGNB) to aminoglycosides. A total of 378 NFGNB blood isolates causing healthcare-associated bloodstream infections during 2008 and 2013 at four medical centers in Taiwan were tested for their susceptibilities to four aminoglycosides using the agar dilution method (gentamicin, amikacin, tobramycin, and isepamicin) and disc diffusion method (isepamicin). A. baumannii was highly resistant to all four aminoglycosides (range of susceptibility, 0-4%), whereas >80% of Acinetobacter nosocomialis and Acinetobacter pittii blood isolates were susceptible to amikacin (susceptibility: 96% and 91%, respectively), tobramycin (susceptibility: 92% and 80%, respectively), and isepamicin (susceptibility: 96% and 80%, respectively). All aminoglycosides except gentamicin possessed good in vitro activity (>94%) against P. aeruginosa. Amikacin has the best in vitro activity against P. aeruginosa (susceptibility, 98%), followed by A. nosocomialis (96%), and A. pittii (91%), whereas tobramycin and isepamicin were less potent against A. pittii (both 80%). Aminoglycoside resistances were prevalent in Stenotrophomonas maltophilia and Burkholderia cepacia complex blood isolates in Taiwan. Genospecies among the A. baumannii complex had heterogeneous susceptibility profiles to aminoglycosides. Aminoglycosides, except gentamicin, remained good in vitro antimicrobial activity against P. aeruginosa. Further in vivo clinical data and continuous resistance monitoring are warranted for clinical practice guidance. Copyright © 2015. Published by Elsevier B.V.

  7. Collateral sensitivity between aminoglycosides and beta-lactam antibiotics depends on active proton pumps.

    Science.gov (United States)

    Azimi, Leila; Rastegar Lari, Abdolaziz

    2017-11-01

    Selection inversion is the hypothesis for antibiotic resistant inhabitation in bacteria and collateral sensitivity is one of the proposed phenomena for achievement of this hypothesis. The presence of collateral sensitivity associated with the proton motivation pump between the aminoglycosides and beta-lactam group of antibiotics is one of the examples of collateral sensitivity in some studies. The aim of this study was to demonstrate that collateral sensitivity between aminoglycosides and beta-lactam antibiotics associated with proton motivation pump may not be true in all cases. In this study, 100 Pseudomonas aeruginosa were surveyed. Gentamicin and imipenem-resistant strains were confirmed by disc diffusion method and MIC. Active proton motivation pumps were screened by pumps inhibitor. Semi-quantitative Real-Time PCR assay was used to confirm gene overexpression. Seventy-six and 79 out of 100 strains were resistant to gentamicin and imipenem, respectively. Seventy-five strains were resistant to both gentamicin and imipenem. The results of proton pump inhibitor test showed the involvement of active proton motivation pump in 22 of 75 imipenem- and gentamicin-resistant strains. According to Real - Time PCR assay, mexX efflux gene was overexpressed in the majority of isolates tested. The collateral sensitivity effect cannot explain the involvement of active proton motivation pumps in both imipenem and gentamicin-resistant strains simultaneously. Active and/or inactive proton pump in gentamicin-sensitive and/or resistant strains cannot be a suitable example for explanation of collateral sensitivity between aminoglycosides and beta-lactam antibiotics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Identification of Genes Coding Aminoglycoside Modifying Enzymes in E. coli of UTI Patients in India

    Directory of Open Access Journals (Sweden)

    Abdul Rouf Mir

    2016-01-01

    Full Text Available This study is to probe the pattern of antibiotic resistance against aminoglycosides and its mechanism in E. coli obtained from patients from Chennai, India. Isolation and identification of pathogens were done on MacConkey agar. Antimicrobial sensitivity testing was done by disc diffusion test. The identification of genes encoding aminoglycoside modifying enzymes was done by Polymerase Chain Reaction (PCR. Out of 98 isolates, 71 (72.45% isolates were identified as E. coli and the remaining 27 (27.55% as other bacteria. Disc diffusion method results showed a resistance level of 72.15% for streptomycin, 73.4% for gentamicin, 63.26% for neomycin, 57.14% for tobramycin, 47.9% for netilmicin, and 8.16% for amikacin in E. coli. PCR screening showed the presence of four genes, namely, rrs, aacC2, aacA-aphD, and aphA3, in their plasmid DNA. The results point towards the novel mechanism of drug resistance in E. coli from UTI patients in India as they confirm the presence of genes encoding enzymes that cause resistance to aminoglycoside drugs. This could be an alarm for drug prescription to UTI patients.

  9. Identification of Genes Coding Aminoglycoside Modifying Enzymes in E. coli of UTI Patients in India.

    Science.gov (United States)

    Mir, Abdul Rouf; Bashir, Yasir; Dar, Firdous Ahmad; Sekhar, M

    This study is to probe the pattern of antibiotic resistance against aminoglycosides and its mechanism in E. coli obtained from patients from Chennai, India. Isolation and identification of pathogens were done on MacConkey agar. Antimicrobial sensitivity testing was done by disc diffusion test. The identification of genes encoding aminoglycoside modifying enzymes was done by Polymerase Chain Reaction (PCR). Out of 98 isolates, 71 (72.45%) isolates were identified as E. coli and the remaining 27 (27.55%) as other bacteria. Disc diffusion method results showed a resistance level of 72.15% for streptomycin, 73.4% for gentamicin, 63.26% for neomycin, 57.14% for tobramycin, 47.9% for netilmicin, and 8.16% for amikacin in E. coli. PCR screening showed the presence of four genes, namely, rrs, aacC2, aacA-aphD, and aphA3, in their plasmid DNA. The results point towards the novel mechanism of drug resistance in E. coli from UTI patients in India as they confirm the presence of genes encoding enzymes that cause resistance to aminoglycoside drugs. This could be an alarm for drug prescription to UTI patients.

  10. Occurrence of aminoglycoside-modifying enzymes among isolates of Escherichia coli exhibiting high levels of aminoglycoside resistance isolated from Korean cattle farms.

    Science.gov (United States)

    Belaynehe, Kuastros Mekonnen; Shin, Seung Won; Hong-Tae, Park; Yoo, Han Sang

    2017-08-01

    This study investigated 247 Escherichia coli isolates collected from four cattle farms to characterize aminoglycoside-modifying enzyme (AME) genes, their plasmid replicons and transferability. Out of 247 isolates a high number of isolates (total 202; 81.78%) were found to be resistant to various antibiotics by disc diffusion. Of the 247 strains, 139 (56.3%) were resistant to streptomycin, and other antibiotic resistances followed as tetracycline (12.15%), ampicillin (7%), chloramphenicol (5.7%) and trimethoprim-sulfamethoxazole (0.8%). Among 247 isolates B1 was the predominant phylogenetic group identified comprising 151 isolates (61.1%), followed by groups A (27.9%), D (7%) and B2 (4%). Out of 139 isolates investigated for AME, 130 (93.5%) isolates carried at least one AME gene. aph3″-1a and aph3″-1b (46%) were the principal genes detected, followed by aac3-IVa (34.5%). ant2″-1a was the least detected gene (2.2%). Nine (6.5%) strains carried no AME genes. Twelve (63.2%) among 19 isolates transferred an AME gene to a recipient and aph3΄-1a was the dominant transferred gene. Transferability mainly occurred via the IncFIB replicon type (52.6%). Pulsed-field gel electrophoresis typing demonstrated a higher degree of diversity with 14 distinct cluster types. This result suggests that commensal microflora from food-producing animals has a tremendous ability to harbor and transfer AME genes, and poses a potential risk by dissemination of resistance to humans through the food chain. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Impact of aminoglycoside cycling in six tertiary intensive care units: prospective longitudinal interventional study.

    Science.gov (United States)

    Francetić, Igor; Kalenić, Smilja; Huić, Mirjana; Mercep, Iveta; Makar-Ausperger, Ksenija; Likić, Robert; Erdeljić, Viktorija; Tripković, Vesna; Simić, Petra

    2008-04-01

    To determine the effect of aminoglycoside cycling in six tertiary intensive care units (ICU) on the rates of sepsis, aminoglycoside resistance patterns, antibiotic consumption, and costs. This was a prospective longitudinal interventional study that measured the effect of change from first-line gentamicin usage (February 2002-February 2003) to amikacin usage (February 2003-February 2004) on the aminoglycoside resistance patterns, number of patients with gram-negative bacteremia, consumption of antibiotics, and the cost of antimicrobial drugs in 6 tertiary care ICUs in Zagreb, Croatia. The change from first-line gentamicin to amikacin usage led to a decrease in the overall gentamicin resistance of gram-negative bacteria (GNB) from 42% to 26% (PAcinetobacter baumanni (P=0.014). Sepsis rate in ICUs was reduced from 3.6% to 2.2% (P<0.001; chi(2) test), with a decline in the number of nosocomial bloodstream infections from 55/100 patient-days to 26/100 patient-days (P=0.001, chi(2) test). Furthermore, amikacin use led to a 16% decrease in the overall antibiotic consumption and 0.1 euro/patient/d cost reduction. Exclusive use of amikacin significantly reduced the resistance of GNB isolates to gentamicin and netilmicin, the number of GNB nosocomial bacteremias, and the cost of total antibiotic usage in ICUs.

  12. Purification, crystallization and preliminary X-ray analysis of the aminoglycoside-6′-acetyltransferase AAC(6′)-Im

    International Nuclear Information System (INIS)

    Toth, Marta; Vakulenko, Sergei B.; Smith, Clyde A.

    2012-01-01

    AAC(6′)-Im is an N-acetyltransferase enzyme responsible for aminoglycoside resistance in E. faecium and E. coli isolates. Crystals of the kanamycin complex of this enzyme have been prepared and preliminary X-ray diffraction experiments have been undertaken. Bacterial resistance to the aminoglycoside antibiotics is primarily the result of enzymatic deactivation of the drugs. The aminoglycoside N-acetyltransferases (AACs) are a large family of bacterial enzymes that are responsible for coenzyme-A-facilitated acetylation of aminoglycosides. The gene encoding one of these enzymes, AAC(6′)-Im, has been cloned and the protein (comprising 178 amino-acid residues) was expressed in Escherichia coli, purified and crystallized as the kanamycin complex. Synchrotron diffraction data to approximately 2.0 Å resolution were collected from a crystal of this complex on beamline BL12-2 at SSRL (Stanford, California, USA). The crystals belonged to the hexagonal space group P6 5 , with approximate unit-cell parameters a = 107.75, c = 37.33 Å, and contained one molecule in the asymmetric unit. Structure determination is under way using molecular replacement

  13. Distribution of 16S rRNA Methylases Among Different Species of Aminoglycoside-Resistant Enterobacteriaceae in a Tertiary Care Hospital in Poland.

    Science.gov (United States)

    Piekarska, Katarzyna; Zacharczuk, Katarzyna; Wołkowicz, Tomasz; Rzeczkowska, Magdalena; Bareja, Elżbieta; Olak, Monika; Gierczyński, Rafał

    2016-01-01

    Aminoglycosides are a group of antimicrobial agents still the most commonly used in the treatment of life-threatening bacterial infections in human and animals. The emergence and spread of 16S rRNA methylases, which confer high-level resistance to the majority of clinically relevant aminoglycosides, constitute a major public health concern. Our goal was to evaluate the distribution of 16S rRNA methylases among different species of Enterobacteriaceae during a five month-long survey in a tertiary hospital in Warszawa, Poland. In the survey, a total of 1770 non-duplicate clinical isolates were collected from all hospital wards in a tertiary hospital in Warszawa, Poland. The survey was conducted between 19 April and 19 September 2010. The ability to produce 16S rRNA methylase was examined by determining MICs for gentamicin, kanamycin, amikacin by means of the agar dilution method. The isolates resistant to high concentration of aminoglycosides were PCR tested for genes: armA, rmtA, rmtB and rmtC. PCR products were subjected to DNA sequencing by the Sanger method. The genetic similarity of the ArmA-producing isolates was analysed by pulsed-filed gel electrophoresis (PFGE). ArmA was the only 16S rRNA methylase detected in 20 of 1770 tested isolates. The overall prevalence rate of ArmA was 1.13%. In K. pneumoniae (n = 742), P. mirabilis (n = 130), and E. cloacae (n = 253) collected in the survey, the prevalence of ArmA was 0.4%, 0.8% and 5.9%, respectively. The PFGE revealed both horizontal and clonal spread of the armA gene in the hospital. The prevalence of 16S rRNA methylase ArmA reported in this study is significantly higher than observed in other countries in Europe.

  14. Efficient transformation and regeneration of transgenic cassava using the neomycin phosphotransferase gene as aminoglycoside resistance marker gene.

    Science.gov (United States)

    Niklaus, Michael; Gruissem, Wilhelm; Vanderschuren, Hervé

    2011-01-01

    Cassava is one of the most important crops in the tropics. Its industrial use for starch and biofuel production is also increasing its importance for agricultural production in tropical countries. In the last decade cassava biotechnology has emerged as a valuable alternative to the breeding constraints of this highly heterozygous crop for improved trait development of cassava germplasm. Cassava transformation remains difficult and time-consuming because of limitations in selecting transgenic tissues and regeneration of transgenic plantlets. We have recently reported an efficient and robust cassava transformation protocol using the hygromycin phosphotransferase II (hptII) gene as selection marker and the aminoglycoside hygromycin at optimal concentrations to maximize the regeneration of transgenic plantlets. In the present work, we expanded the transformation protocol to the use of the neomycin phosphotransferase II (nptII) gene as selection marker. Several aminoglycosides compatible with the use of nptII were tested and optimal concentrations for cassava transformation were determined. Given its efficiency equivalent to hptII as selection marker with the described protocol, the use of nptII opens new possibilities to engineer transgenic cassava lines with multiple T-DNA insertions and to produce transgenic cassava with a resistance marker gene that is already deregulated in several commercial transgenic crops.

  15. Causative Agents of Aspergillosis Including Cryptic Aspergillus Species and A. fumigatus.

    Science.gov (United States)

    Toyotome, Takahito

    2016-01-01

    Aspergillosis is an important deep mycosis. The causative agents are Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, and Aspergillus terreus, of which A. fumigatus is the most prevalent. Cryptic Aspergillus spp., which morphologically resemble representative species of each Aspergillus section, also cause aspergillosis. Most of the cryptic species reveal different susceptibility patterns and/or different secondary metabolite profiles, also called exometabolome in this manuscript, from those representative species. On the other hand, azole-resistant A. fumigatus strains in clinical specimens and in the environment have been reported. Therefore, it is imperative to precisely identify the species, including cryptic Aspergillus spp., and evaluate the susceptibility of isolates.In this manuscript, some of the causative cryptic Aspergillus spp. are briefly reviewed. In addition, the exometabolome of Aspergillus section Fumigati is described. Finally, azole resistance of A. fumigatus is also discussed, in reference to several studies from Japan.

  16. Parallel Evolution of High-Level Aminoglycoside Resistance in Escherichia coli Under Low and High Mutation Supply Rates

    Directory of Open Access Journals (Sweden)

    Claudia Ibacache-Quiroga

    2018-03-01

    Full Text Available Antibiotic resistance is a major concern in public health worldwide, thus there is much interest in characterizing the mutational pathways through which susceptible bacteria evolve resistance. Here we use experimental evolution to explore the mutational pathways toward aminoglycoside resistance, using gentamicin as a model, under low and high mutation supply rates. Our results show that both normo and hypermutable strains of Escherichia coli are able to develop resistance to drug dosages > 1,000-fold higher than the minimal inhibitory concentration for their ancestors. Interestingly, such level of resistance was often associated with changes in susceptibility to other antibiotics, most prominently with increased resistance to fosfomycin. Whole-genome sequencing revealed that all resistant derivatives presented diverse mutations in five common genetic elements: fhuA, fusA and the atpIBEFHAGDC, cyoABCDE, and potABCD operons. Despite the large number of mutations acquired, hypermutable strains did not pay, apparently, fitness cost. In contrast to recent studies, we found that the mutation supply rate mainly affected the speed (tempo but not the pattern (mode of evolution: both backgrounds acquired the mutations in the same order, although the hypermutator strain did it faster. This observation is compatible with the adaptive landscape for high-level gentamicin resistance being relatively smooth, with few local maxima; which might be a common feature among antibiotics for which resistance involves multiple loci.

  17. Genetic Structure and Antimicrobial Resistance of Escherichia coli and Cryptic Clades in Birds with Diverse Human Associations.

    Science.gov (United States)

    Blyton, Michaela D J; Pi, Hongfei; Vangchhia, Belinda; Abraham, Sam; Trott, Darren J; Johnson, James R; Gordon, David M

    2015-08-01

    The manner and extent to which birds associate with humans may influence the genetic attributes and antimicrobial resistance of their commensal Escherichia communities through strain transmission and altered selection pressures. In this study, we determined whether the distribution of the different Escherichia coli phylogenetic groups and cryptic clades, the occurrence of 49 virulence associated genes, and/or the prevalence of resistance to 12 antimicrobials differed between four groups of birds from Australia with contrasting types of human association. We found that birds sampled in suburban and wilderness areas had similar Escherichia communities. The Escherichia communities of backyard domestic poultry were phylogenetically distinct from the Escherichia communities sourced from all other birds, with a large proportion (46%) of poultry strains belonging to phylogenetic group A and a significant minority (17%) belonging to the cryptic clades. Wild birds sampled from veterinary and wildlife rehabilitation centers (in-care birds) carried Escherichia isolates that possessed particular virulence-associated genes more often than Escherichia isolates from birds sampled in suburban and wilderness areas. The Escherichia isolates from both the backyard poultry and in-care birds were more likely to be multidrug resistant than the Escherichia isolates from wild birds. We also detected a multidrug-resistant E. coli strain circulating in a wildlife rehabilitation center, reinforcing the importance of adequate hygiene practices when handling and caring for wildlife. We suggest that the relatively high frequency of antimicrobial resistance in the in-care birds and backyard poultry is due primarily to the use of antimicrobials in these animals, and we recommend that the treatment protocols used for these birds be reviewed. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Clinical pharmacokinetics of aminoglycosides in the neonate: a review.

    Science.gov (United States)

    Pacifici, Gian Maria

    2009-04-01

    Sepsis is common in neonates and is a major cause of morbidity and mortality. Sixty percent of preterm neonates receive at least one antibiotic, and 43% of the antibiotics administered to these neonates are aminoglycosides. The clearance (Cl), serum half-life (t(1/2)), and volume of distribution (Vd) of aminoglycosides change during the neonatal life, and the pharmacokinetics of aminoglycosides need to be studied in neonates in order to optimise therapy with these drugs. The aim of this work is to review the published data on the pharmacokinetics of aminoglycosides in order to provide a critical analysis of the literature that can be a useful tool in the hands of physicians. The bibliographic search was performed electronically using PubMed, as the search engine, through July 11th, 2008. Firstly, a Medline search was performed with the keywords "pharmacokinetics of aminoglycosides in neonates" with the limit of "human". Other Medline searches were performed with the keywords "pharmacokinetics of ... in neonates" followed by the name of the aminoglycosides: amikacin, gentamicin, netilmicin and tobramycin. In addition, the book Neofax: A Manual of Drugs Used in Neonatal Care by Young and Mangum (Thomson Healthcare, 2007) was consulted. The aminoglycosides are mainly eliminated by the kidney, and their elimination rates are reduced at birth. As a consequence Cl is reduced and t(1/2) is prolonged in the neonate as compared to more mature infants. The high body-water content of the neonate results in a large Vd of aminoglycosides as these drugs are fairly water soluble. Postnatal development is an important factor in the maturation of the neonate, and as postnatal age proceeds, Cl of aminoglycosides increases. The maturation of the kidney governs the pharmacokinetics of aminoglycosides in the infant. Cl and t(1/2) are influenced by development, and this must be taken into consideration when planning a dosage regimen with aminoglycosides in the neonate. Aminoglycosides

  19. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup

    2013-01-01

    Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we...... provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release......-deficient P. aeruginosa quorum-sensing mutant are more susceptible to aminoglycoside treatment than wild-type biofilms but become rescued from the detrimental action of aminoglycosides upon supplementation with exogenous DNA. Furthermore, we demonstrate that exposure to lysed polymorphonuclear leukocytes...

  20. Therapeutic drug monitoring of aminoglycosides in neonates

    NARCIS (Netherlands)

    Touw, Daniël J; Westerman, Elsbeth M; Sprij, Arwen J

    2009-01-01

    The efficacy and toxicity of aminoglycosides show a strong direct positive relationship with blood drug concentrations, therefore, therapy with aminoglycosides in adults is usually guided by therapeutic drug monitoring. Dosing regimens in adults have evolved from multiple daily dosing to

  1. Dosing strategy based on prevailing aminoglycoside minimum inhibitory concentration in India: Evidence and issues

    Directory of Open Access Journals (Sweden)

    Balaji Veeraraghavan

    2017-01-01

    Full Text Available Aminoglycosides are important agents used for treating drug-resistant infections. The current dosing regimen of aminoglycosides does not achieve sufficient serum level concentration for the infected bacterial pathogen interpreted as susceptible based on laboratory testing. Minimum inhibitory concentration was determined for nearly 2000 isolates of Enterobacteriaceae and Pseudomonas aeruginosa by broth microdilution method. Results were interpreted based on CLSI and EUCAST interpretative criteria and the inconsistencies in the susceptibility profile were noted. This study provides insights into the inconsistencies existing in the laboratory interpretation and the corresponding clinical success rates. This urges the need for revising clinical breakpoints for amikacin, to resolve under dosing leading to clinical failure.

  2. Structural characterization of the novel aminoglycoside phosphotransferase AphVIII from Streptomyces rimosus with enzymatic activity modulated by phosphorylation

    Energy Technology Data Exchange (ETDEWEB)

    Boyko, Konstantin M., E-mail: kmb@inbi.ras.ru [Bach Institute of Biochemistry, Federal Research Centre of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, Bld. 2, 119071, Moscow (Russian Federation); National Research Center “Kurchatov Institute”, Kurchatov Complex of NBICS-technologies, Akad. Kurchatova sqr., 1, Moscow, 123182 (Russian Federation); Gorbacheva, Marina A.; Korzhenevskiy, Dmitry A. [National Research Center “Kurchatov Institute”, Kurchatov Complex of NBICS-technologies, Akad. Kurchatova sqr., 1, Moscow, 123182 (Russian Federation); Alekseeva, Maria G.; Mavletova, Dilara A.; Zakharevich, Natalia V.; Elizarov, Sergey M.; Rudakova, Natalia N.; Danilenko, Valery N. [Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkina str. 3, Moscow, 119333 (Russian Federation); Popov, Vladimir O. [Bach Institute of Biochemistry, Federal Research Centre of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, Bld. 2, 119071, Moscow (Russian Federation); National Research Center “Kurchatov Institute”, Kurchatov Complex of NBICS-technologies, Akad. Kurchatova sqr., 1, Moscow, 123182 (Russian Federation)

    2016-09-02

    Aminoglycoside phosphotransferases represent a broad class of enzymes that promote bacterial resistance to aminoglycoside antibiotics via the phosphorylation of hydroxyl groups in the latter. Here we report the spatial structure of the 3′-aminoglycoside phosphotransferase of novel VIII class (AphVIII) solved by X-ray diffraction method with a resolution of 2.15 Å. Deep analysis of APHVIII structure and its comparison with known structures of aminoglycoside phosphotransferases of various types reveals that AphVIII has a typical two-domain fold and, however, possesses some unique characteristics that distinguish the enzyme from its known homologues. The most important difference is the presence of the activation loop with unique Ser146 residue. We demonstrate that in the apo-state of the enzyme the activation loop does not interact with other parts of the enzyme and seems to adopt catalytically competent state only after substrate binding. - Highlights: • 3D structure of the novel aminoglycoside phosphotransferase AphVIII was obtained. • AphVIII activation loop is clearly identified in the electron density. • AphVIII has some unique structural features in its substrate C-ring binding pocket.

  3. Crystallization and preliminary crystallographic analysis of an aminoglycoside kinase from Legionella pneumophila

    International Nuclear Information System (INIS)

    Lemke, Christopher T.; Hwang, Jiyoung; Xiong, Bing; Cianciotto, Nicholas P.; Berghuis, Albert M.

    2005-01-01

    Two crystal forms of the antibiotic resistance enzyme APH(9)-Ia from L. pneumophila are reported. 9-Aminoglycoside phosphotransferase type Ia [APH(9)-Ia] is a resistance factor in Legionella pneuemophila, the causative agent of legionnaires’ disease. It is responsible for providing intrinsic resistance to the antibiotic spectinomycin. APH(9)-Ia phosphorylates one of the hydroxyl moieties of spectinomycin in an ATP-dependent manner, abolishing the antibiotic properties of this drug. Here, the crystallization and preliminary X-ray studies of this enzyme in two crystal forms is reported. One of the these crystal forms provides diffraction data to a resolution of 1.7 Å

  4. Sublethal Triclosan Exposure Decreases Susceptibility to Gentamicin and Other Aminoglycosides in Listeria monocytogenes

    DEFF Research Database (Denmark)

    Christensen, Ellen Gerd; Gram, Lone; Kastbjerg, Vicky Gaedt

    2011-01-01

    (containing quaternary ammonium compound) in four consecutive cultures did not alter the frequency of antibiotic-tolerant isolates, as determined by plating on 2x the MIC for a range of antibiotics. Exposure of eight strains of L. monocytogenes to 1 and 4 µg/ml triclosan did not alter triclosan sensitivity...... resistance remained at a high level also after five subcultures without triclosan or gentamicin. Aminoglycoside resistance can be caused by mutations in the target site, the 16S rRNA gene. However, such mutations were not detected in the N53-1-resistant isolates. A combination of gentamicin and ampicillin...

  5. Modulation of RNA function by aminoglycoside antibiotics.

    Science.gov (United States)

    Schroeder, R; Waldsich, C; Wank, H

    2000-01-04

    One of the most important families of antibiotics are the aminoglycosides, including drugs such as neomycin B, paromomycin, gentamicin and streptomycin. With the discovery of the catalytic potential of RNA, these antibiotics became very popular due to their RNA-binding capacity. They serve for the analysis of RNA function as well as for the study of RNA as a potential therapeutic target. Improvements in RNA structure determination recently provided first insights into the decoding site of the ribosome at high resolution and how aminoglycosides might induce misreading of the genetic code. In addition to inhibiting prokaryotic translation, aminoglycosides inhibit several catalytic RNAs such as self-splicing group I introns, RNase P and small ribozymes in vitro. Furthermore, these antibiotics interfere with human immunodeficiency virus (HIV) replication by disrupting essential RNA-protein contacts. Most exciting is the potential of many RNA-binding antibiotics to stimulate RNA activities, conceiving small-molecule partners for the hypothesis of an ancient RNA world. SELEX (systematic evolution of ligands by exponential enrichment) has been used in this evolutionary game leading to small synthetic RNAs, whose NMR structures gave valuable information on how aminoglycosides interact with RNA, which could possibly be used in applied science.

  6. Information accessibility and cryptic processes

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, John R; Ellison, Christopher J; Crutchfield, James P [Complexity Sciences Center and Physics Department, University of California at Davis, One Shields Avenue, Davis, CA 95616 (United States)], E-mail: jrmahoney@ucdavis.edu, E-mail: cellison@cse.ucdavis.edu, E-mail: chaos@cse.ucdavis.edu

    2009-09-11

    We give a systematic expansion of the crypticity-a recently introduced measure of the inaccessibility of a stationary process's internal state information. This leads to a hierarchy of k-cryptic processes and allows us to identify finite-state processes that have infinite cryptic order-the internal state information is present across arbitrarily long, observed sequences. The crypticity expansion is exact in both the finite- and infinite-order cases. It turns out that k-crypticity is complementary to the Markovian finite-order property that describes state information in processes. One application of these results is an efficient expansion of the excess entropy-the mutual information between a process's infinite past and infinite future-that is finite and exact for finite-order cryptic processes. (fast track communication)

  7. Identification of genes involved in low aminoglycoside-induced SOS response in Vibrio cholerae: a role for transcription stalling and Mfd helicase.

    Science.gov (United States)

    Baharoglu, Zeynep; Babosan, Anamaria; Mazel, Didier

    2014-02-01

    Sub-inhibitory concentrations (sub-MIC) of antibiotics play a very important role in selection and development of resistances. Unlike Escherichia coli, Vibrio cholerae induces its SOS response in presence of sub-MIC aminoglycosides. A role for oxidized guanine residues was observed, but the mechanisms of this induction remained unclear. To select for V. cholerae mutants that do not induce low aminoglycoside-mediated SOS induction, we developed a genetic screen that renders induction of SOS lethal. We identified genes involved in this pathway using two strategies, inactivation by transposition and gene overexpression. Interestingly, we obtained mutants inactivated for the expression of proteins known to destabilize the RNA polymerase complex. Reconstruction of the corresponding mutants confirmed their specific involvement in induction of SOS by low aminoglycoside concentrations. We propose that DNA lesions formed on aminoglycoside treatment are repaired through the formation of single-stranded DNA intermediates, inducing SOS. Inactivation of functions that dislodge RNA polymerase leads to prolonged stalling on these lesions, which hampers SOS induction and repair and reduces viability under antibiotic stress. The importance of these mechanisms is illustrated by a reduction of aminoglycoside sub-MIC. Our results point to a central role for transcription blocking at DNA lesions in SOS induction, so far underestimated.

  8. ACTIVATION OF A CRYPTIC D-SERINE DEAMINASE (DSD) GENE FROM PSEUDOMONAS CEPACIA 17616

    Science.gov (United States)

    D-serine inhibits growth of P. cepacia 17616; however, resistant mutants able to express an ordinarily cryptic D-serine deaminase (dsd) gene were isolated readily. The resistant strains formed high levels of a D-serine deaminase active on D-threonine as well as D-serine. IS eleme...

  9. Efflux Pump-mediated Drug Resistance in Burkholderia

    Directory of Open Access Journals (Sweden)

    Nicole L Podnecky

    2015-04-01

    Full Text Available Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in B. cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.

  10. Options for treating carbapenem-resistant Enterobacteriaceae.

    Science.gov (United States)

    Rafailidis, Petros I; Falagas, Matthew E

    2014-12-01

    To address the therapeutic management of carbapenem-resistant Enterobacteriaceae on the basis of literature of the last 12 months. Retrospective and prospective (nonrandomized noncontrolled) studies provide data regarding the management of infections due to carbapenem-resistant Enterobacteriaceae. The combination of a carbapenem with colistin or high-dose tigecycline or aminoglycoside or even triple carbapenem-containing combinations if the minimum inhibitory concentration (MIC) range of carbapenem (meropenem and imipenem) resistance is 8 mg/l or less seems to have an advantage over monotherapy with either colistin or tigecycline or fosfomycin. For Enterobacteriaceae with MIC for carbapenems over 8 mg/l, combination regimens involve colistin, tigecycline usually administered in a double dose than that suggested by its manufacturer, fosfomycin and aminoglycosides in various combinations. Suggestions based on the limited literature cannot be made safely. Combination regimens involving carbapenems for Enterobacteriaceae with MICs 8 mg/l or less for carbapenems (in dual combination with colistin or high-dose tigecycline or aminoglycoside or even triple combinations) seem to confer some therapeutic advantage over monotherapy. For Enterobacteriaceae with higher than the above-mentioned MICs, a combination of two or even three antibiotics among colistin, high-dose tigecycline, aminoglycoside and fosfomycin seems to confer decreased mortality.

  11. In vitro bactericidal activity of aminoglycosides, including the next-generation drug plazomicin, against Brucella spp.

    Science.gov (United States)

    Plazomicin is a next-generation aminoglycoside with a potentially improved safety profile compared to other aminoglycosides. This study assessed plazomicin MICs and MBCs in four Brucella spp. reference strains. Like other aminoglycosides and aminocyclitols, plazomicin MBC values equaled MIC values ...

  12. Clinical Pharmacokinetics of Penicillins, Cephalosporins and Aminoglycosides in the Neonate: A Review

    Directory of Open Access Journals (Sweden)

    Gian Maria Pacifici

    2010-08-01

    Full Text Available Bacterial infections are common in the neonates and are a major cause of morbidity and mortality. Sixty percent of preterm infants admitted to neonatal intensive care units received at least one antibiotic during the first week of life. Penicillins, aminoglycosides and cephalosporins comprised 53, 43 and 16%, respectively. Kinetic parameters such as the half-life (t1/2, clearance (Cl, and volume of distribution (Vd change with development, so the kinetics of penicillins, cephalosporins and aminoglycosides need to be studied in order to optimise therapy with these drugs. The aim of this study is to review the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate in a single article in order to provide a critical analysis of the literature and thus provide a useful tool in the hands of physicians. The bibliographic search was performed electronically using PubMed, as the search engine, until February 2nd, 2010. Medline search terms were as follows: pharmacokinetics AND (penicillins OR cephalosporins OR aminoglycosides AND infant, newborn, limiting to humans. Penicillins, cephalosporins and aminoglycosides are fairly water soluble and are mainly eliminated by the kidneys. The maturation of the kidneys governs the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate. The renal excretory function is reduced in preterms compared to term infants and Cl of these drugs is reduced in premature infants. Gestational and postnatal ages are important factors in the maturation of the neonate and, as these ages proceed, Cl of penicillins, cephalosporins and aminoglycosides increases. Cl and t1/2 are influenced by development and this must be taken into consideration when planning a dosage regimen with these drugs. More pharmacokinetic studies are required to ensure that the dose recommended for the treatment of sepsis in the neonate is evidence based.

  13. Local Mechanisms for Loud Sound-Enhanced Aminoglycoside Entry into Outer Hair Cells

    Directory of Open Access Journals (Sweden)

    Hongzhe eLi

    2015-04-01

    Full Text Available Loud sound exposure exacerbates aminoglycoside ototoxicity, increasing the risk of permanent hearing loss and degrading the quality of life in affected individuals. We previously reported that loud sound exposure induces temporary threshold shifts (TTS and enhances uptake of aminoglycosides, like gentamicin, by cochlear outer hair cells (OHCs. Here, we explore mechanisms by which loud sound exposure and TTS could increase aminoglycoside uptake by OHCs that may underlie this form of ototoxic synergy.Mice were exposed to loud sound levels to induce TTS, and received fluorescently-tagged gentamicin (GTTR for 30 minutes prior to fixation. The degree of TTS was assessed by comparing auditory brainstem responses before and after loud sound exposure. The number of tip links, which gate the GTTR-permeant mechanoelectrical transducer (MET channels, was determined in OHC bundles, with or without exposure to loud sound, using scanning electron microscopy.We found wide-band noise (WBN levels that induce TTS also enhance OHC uptake of GTTR compared to OHCs in control cochleae. In cochlear regions with TTS, the increase in OHC uptake of GTTR was significantly greater than in adjacent pillar cells. In control mice, we identified stereociliary tip links at ~50% of potential positions in OHC bundles. However, the number of OHC tip links was significantly reduced in mice that received WBN at levels capable of inducing TTS.These data suggest that GTTR uptake by OHCs during TTS occurs by increased permeation of surviving, mechanically-gated MET channels, and/or non-MET aminoglycoside-permeant channels activated following loud sound exposure. Loss of tip links would hyperpolarize hair cells and potentially increase drug uptake via aminoglycoside-permeant channels expressed by hair cells. The effect of TTS on aminoglycoside-permeant channel kinetics will shed new light on the mechanisms of loud sound-enhanced aminoglycoside uptake, and consequently on ototoxic

  14. Aminoglycoside antibiotics and autism: a speculative hypothesis

    Directory of Open Access Journals (Sweden)

    Manev Hari

    2001-10-01

    Full Text Available Abstract Background Recently, it has been suspected that there is a relationship between therapy with some antibiotics and the onset of autism; but even more curious, some children benefited transiently from a subsequent treatment with a different antibiotic. Here, we speculate how aminoglycoside antibiotics might be associated with autism. Presentation We hypothesize that aminoglycoside antibiotics could a trigger the autism syndrome in susceptible infants by causing the stop codon readthrough, i.e., a misreading of the genetic code of a hypothetical critical gene, and/or b improve autism symptoms by correcting the premature stop codon mutation in a hypothetical polymorphic gene linked to autism. Testing Investigate, retrospectively, whether a link exists between aminoglycoside use (which is not extensive in children and the onset of autism symptoms (hypothesis "a", or between amino glycoside use and improvement of these symptoms (hypothesis "b". Whereas a prospective study to test hypothesis "a" is not ethically justifiable, a study could be designed to test hypothesis "b". Implications It should be stressed that at this stage no direct evidence supports our speculative hypothesis and that its main purpose is to initiate development of new ideas that, eventually, would improve our understanding of the pathobiology of autism.

  15. Aminoglycosides in septic shock: an overview, with specific consideration given to their nephrotoxic risk.

    Science.gov (United States)

    Boyer, Alexandre; Gruson, Didier; Bouchet, Stéphane; Clouzeau, Benjamin; Hoang-Nam, Bui; Vargas, Frédéric; Gilles, Hilbert; Molimard, Mathieu; Rogues, Anne-Marie; Moore, Nicholas

    2013-04-01

    Aminoglycoside nephrotoxicity has been reported in patients with sepsis, and several risk factors have been described. Once-daily dosing and shorter treatment have reduced nephrotoxicity risk, and simplified aminoglycoside monitoring. This review focuses on nephrotoxicity associated with aminoglycosides in the subset of patients with septic shock or severe sepsis. These patients are radically different from those with less severe sepsis. They may have, for instance, renal impairment due to the shock per se, sepsis-related acute kidney injury, frequent association with pre-existing risk factors for renal failure such as diabetes, dehydration and other nephrotoxic treatments. In this category of patients, these risk factors might modify substantially the benefit-risk ratio of aminoglycosides. In addition, aminoglycoside administration in critically ill patients with sepsis is complicated by an extreme inter- and intra-individual variability in drug pharmacokinetic/pharmacodynamic characteristics: the volume of distribution (Vd) is frequently increased while the elimination constant can be either increased or decreased. Consequently, and although its effect on nephrotoxicity has not been explored, a different administration schedule, i.e. a high-dose once daily (HDOD), and several therapeutic drug monitoring (TDM) options have been proposed in these patients. This review describes the historical perspective of these different options, including those applying to subsets of patients in which aminoglycoside administration is even more complex (obese intensive care unit [ICU] patients, patients needing continuous or discontinuous renal replacement therapy [CRRT/DRRT]). A simple linear dose adjustment according to aminoglycoside serum concentration can be classified as low-intensity TDM. Nomograms have also been proposed, based on the maximum (peak) plasma concentration (Cmax) objectives, weight and creatinine clearance. The Sawchuk and Zaske method (based on the

  16. Inhibition by Commercial Aminoglycosides of Human Connexin Hemichannels Expressed in Bacteria

    Directory of Open Access Journals (Sweden)

    Mariana C. Fiori

    2017-11-01

    Full Text Available In addition to gap junctional channels that mediate cell-to-cell communication, connexins form hemichannels that are present at the plasma membrane. Since hemichannels are permeable to small hydrophilic compounds, including metabolites and signaling molecules, their abnormal opening can cause or contribute to cell damage in disorders such as cardiac infarct, stroke, deafness, skin diseases, and cataracts. Therefore, hemichannels are potential pharmacological targets. A few aminoglycosides, well-known broad-spectrum antibiotics, have been shown to inhibit hemichannels. Here, we tested several commercially available aminoglycosides for inhibition of human connexin hemichannels using a cell-based bacterial growth complementation assay that we developed recently. We found that kanamycin A, kanamycin B, geneticin, neomycin, and paromomycin are effective inhibitors of hemichannels formed by connexins 26, 43, and 46 (Cx26, Cx43, and Cx46. Because of the >70 years of clinical experience with aminoglycosides and the fact that several of the aminoglycosides tested here have been used in humans, they are promising starting points for the development of effective connexin hemichannel inhibitors.

  17. Bacterial Enzymes and Antibiotic Resistance- Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-25

    By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β-lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes.

  18. Detection of cryptic species

    International Nuclear Information System (INIS)

    Cockburn, A.F.; Jensen, T.; Seawright, J.A.

    1998-01-01

    Morphologically similar cryptic species are common in insects. In Anopheles mosquitoes morphologically described species are complexes of cryptic species. Cryptic species are of great practical importance for two reasons: first, one or more species of the complex might not be a pest and control efforts directed at the complex as a whole would therefore be partly wasted; and second, genetic (and perhaps biological) control strategies directed against one species of the complex would not affect other species of the complex. At least one SIT effort has failed because the released sterile insect were of a different species and therefore did not mate with the wild insects being targeted. We use a multidisciplinary approach for detection of cryptic species complexes, focusing first on identifying variability in wild populations using RFLPs of mitochondrial and ribosomal RNA genes (mtDNA and rDNA); followed by confirmation using a variety of other techniques. For rapid identification of wild individuals of field collections, we use a DNA dot blot assay. DNA probes can be isolated by differential screening, however we are currently focusing on the sequencing of the rDNA extragenic spacers. These regions are repeated several hundred times per genome in mosquitoes and evolve rapidly. Molecular drive tends to keen the individual genes homogeneous within a species. (author)

  19. Accuracy of genetic code translation and its orthogonal corruption by aminoglycosides and Mg2+ ions.

    Science.gov (United States)

    Zhang, Jingji; Pavlov, Michael Y; Ehrenberg, Måns

    2018-02-16

    We studied the effects of aminoglycosides and changing Mg2+ ion concentration on the accuracy of initial codon selection by aminoacyl-tRNA in ternary complex with elongation factor Tu and GTP (T3) on mRNA programmed ribosomes. Aminoglycosides decrease the accuracy by changing the equilibrium constants of 'monitoring bases' A1492, A1493 and G530 in 16S rRNA in favor of their 'activated' state by large, aminoglycoside-specific factors, which are the same for cognate and near-cognate codons. Increasing Mg2+ concentration decreases the accuracy by slowing dissociation of T3 from its initial codon- and aminoglycoside-independent binding state on the ribosome. The distinct accuracy-corrupting mechanisms for aminoglycosides and Mg2+ ions prompted us to re-interpret previous biochemical experiments and functional implications of existing high resolution ribosome structures. We estimate the upper thermodynamic limit to the accuracy, the 'intrinsic selectivity' of the ribosome. We conclude that aminoglycosides do not alter the intrinsic selectivity but reduce the fraction of it that is expressed as the accuracy of initial selection. We suggest that induced fit increases the accuracy and speed of codon reading at unaltered intrinsic selectivity of the ribosome.

  20. Detection of cryptic species

    Energy Technology Data Exchange (ETDEWEB)

    Cockburn, A F; Jensen, T; Seawright, J A [United States Dept. of Agriculture, Agricultural Research Service, Medical and Veterinary Entomology Research Lab., Gainesville, FL (United States)

    1998-01-01

    Morphologically similar cryptic species are common in insects. In Anopheles mosquitoes morphologically described species are complexes of cryptic species. Cryptic species are of great practical importance for two reasons: first, one or more species of the complex might not be a pest and control efforts directed at the complex as a whole would therefore be partly wasted; and second, genetic (and perhaps biological) control strategies directed against one species of the complex would not affect other species of the complex. At least one SIT effort has failed because the released sterile insect were of a different species and therefore did not mate with the wild insects being targeted. We use a multidisciplinary approach for detection of cryptic species complexes, focusing first on identifying variability in wild populations using RFLPs of mitochondrial and ribosomal RNA genes (mtDNA and rDNA); followed by confirmation using a variety of other techniques. For rapid identification of wild individuals of field collections, we use a DNA dot blot assay. DNA probes can be isolated by differential screening, however we are currently focusing on the sequencing of the rDNA extragenic spacers. These regions are repeated several hundred times per genome in mosquitoes and evolve rapidly. Molecular drive tends to keen the individual genes homogeneous within a species. (author). 11 refs, 2 figs, 2 tabs.

  1. Deciphering the details of RNA aminoglycoside interactions: from atomistic models to biotechnological applications

    Energy Technology Data Exchange (ETDEWEB)

    Ilgu, Muslum [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    A detailed study was done of the neomycin-B RNA aptamer for determining its selectivity and binding ability to both neomycin– and kanamycin-class aminoglycosides. A novel method to increase drug concentrations in cells for more efficiently killing is described. To test the method, a bacterial model system was adopted and several small RNA molecules interacting with aminoglycosides were cloned downstream of T7 RNA polymerase promoter in an expression vector. Then, the growth analysis of E. coli expressing aptamers was observed for 12-hour period. Our analysis indicated that aptamers helped to increase the intracellular concentration of aminoglycosides thereby increasing their efficacy.

  2. Antibiotic resistant enterococci—Tales of a drug resistance gene trafficker

    DEFF Research Database (Denmark)

    Werner, Guido; Coque, Teresa M.; Franz, Charles M.A.P.

    2013-01-01

    Enterococci have been recognized as important hospital-acquired pathogens in recent years, and isolates of E. faecalis and E. faecium are the third- to fourth-most prevalent nosocomial pathogen worldwide. Acquired resistances, especially against penicilin/ampicillin, aminoglycosides (high-level) ...

  3. Radioimmunoassay and radioenzymatic assay of a new aminoglycoside antibiotic, netilmicin

    International Nuclear Information System (INIS)

    Broughton, A.; Strong, J.E.; Pickering, L.K.; Knight, J.; Bodey, G.P.

    1978-01-01

    A radioimmunoassay and a radioenzymatic assay for netilmicin, a new aminoglycoside, were developed in our laboratories to assist in the study of the pharmacology of the drug and establish values for use in its monitoring. The assays are sensitive, precise, and rapid, giving results that correlate (r = 0.90) with each other and with those of a microbiological assay in which Klebsiella pneumoniae is used as the test organism. Preliminary pharmacological studies show the drug to have a biological half-life of 135 min, which is comparable to that for other aminoglycosides

  4. Biofluorescence as a survey tool for cryptic marine species.

    Science.gov (United States)

    De Brauwer, Maarten; Hobbs, Jean-Paul A; Ambo-Rappe, Rohani; Jompa, Jamaluddin; Harvey, Euan S; McIlwain, Jennifer L

    2017-10-06

    As ecosystems come under increasing anthropogenic pressure, rare species face the highest risk of extinction. Paradoxically, data necessary to evaluate the conservation status of rare species are often lacking because of the challenges of detecting species with low abundance. One group of fishes subject to this undersampling bias are those with cryptic body patterns. Twenty-one percent of cryptic fish species assessed for their extinction risk (International Union for Conservation of Nature [IUCN]) are data deficient. We developed a nondestructive method for surveying cryptically patterned marine fishes based on the presence of biofluorescence (underwater biofluorescence census, UBC). Blue LED torches were used to investigate how widespread biofluorescence was in cryptic reef fishes in the Coral Triangle region. The effectiveness of UBC to generate abundance data was tested on a data-deficient pygmy seahorse species (Hippocampus bargibanti) and compared with data obtained from standard underwater visual census (UVC) surveys. We recorded 95 reef fish species displaying biofluorescence, 73 of which had not been previously described as biofluorescent. Of those fish with cryptic patterns, 87% were biofluorescent compared with 9% for noncryptic fishes. The probability of species displaying biofluorescence was 70.9 times greater for cryptic species than for noncryptic species. Almost twice the number of H. bargibanti was counted using the UBC compared with UVC. For 2 triplefin species (Ucla xenogrammus, Enneapterygius tutuilae), the abundance detected with UBC was triple that detected with UVC. The UBC method was effective at finding cryptic species that would otherwise be difficult to detect and thus will reduce interobserver variability inherent to UVC surveys. Biofluorescence is ubiquitous in cryptic fishes, making this method applicable across a wide range of species. Data collected using UBC could be used with multiple IUCN criteria to assess the extinction risk of

  5. Aminoglucósidos: mirada actual desde su historia Aminoglycosides: a present look based on their history

    Directory of Open Access Journals (Sweden)

    Miriam Aliño Santiago

    2007-06-01

    Full Text Available Se refiere la historia, mecanismos de acción y eficacia de los aminoglucósidos en los pacientes pediátricos, así como las limitaciones de su utilidad por el surgimiento de resistencias bacterianas originadas por empleo abusivo. Se presenta la estrategia de administración de monodosis, como alternativa frente al método tradicional de dosis fraccionadas, y también las complicaciones más frecuentes y graves de los aminoglucósidos y su sinergismo con otras familias de antimicrobianos. Y se citan investigaciones realizadas en el país en materia de terapia antibiótica.We referred to history, mechanisms of action and efficacy of aminoglycosides in pediatric patients as well as limitations in their use because of the emergence of bacterial resistance caused by overuse. The one-dose administration strategy as an alternative to the traditional methods of fractioned doses, the most frequent and serious complictions of aminoglycosides and their sinergism with other antimicrobial families were presented. We quoted research studies on antibiotic therapy made in the country.

  6. Detection and Quantification of Ribosome Inhibition by Aminoglycoside Antibiotics in Living Bacteria Using an Orthogonal Ribosome-Controlled Fluorescent Reporter.

    Science.gov (United States)

    Huang, Shijie; Zhu, Xuechen; Melançon, Charles E

    2016-01-15

    The ribosome is the quintessential antibacterial drug target, with many structurally and mechanistically distinct classes of antibacterial agents acting by inhibiting ribosome function. Detecting and quantifying ribosome inhibition by small molecules and investigating their binding modes and mechanisms of action are critical to antibacterial drug discovery and development efforts. To develop a ribosome inhibition assay that is operationally simple, yet provides direct information on the drug target and the mechanism of action, we have developed engineered E. coli strains harboring an orthogonal ribosome-controlled green fluorescent protein (GFP) reporter that produce fluorescent signal when the orthogonal ribosome is inhibited. As a proof of concept, we demonstrate that these strains, when coexpressing homogeneous populations of aminoglycoside resistant ribosomes, act as sensitive and quantitative detectors of ribosome inhibition by a set of 12 structurally diverse aminoglycoside antibiotics. We suggest that this strategy can be extended to quantifying ribosome inhibition by other drug classes.

  7. Pyruvate cycle increases aminoglycoside efficacy and provides respiratory energy in bacteria.

    Science.gov (United States)

    Su, Yu-Bin; Peng, Bo; Li, Hui; Cheng, Zhi-Xue; Zhang, Tian-Tuo; Zhu, Jia-Xin; Li, Dan; Li, Min-Yi; Ye, Jin-Zhou; Du, Chao-Chao; Zhang, Song; Zhao, Xian-Liang; Yang, Man-Jun; Peng, Xuan-Xian

    2018-02-13

    The emergence and ongoing spread of multidrug-resistant bacteria puts humans and other species at risk for potentially lethal infections. Thus, novel antibiotics or alternative approaches are needed to target drug-resistant bacteria, and metabolic modulation has been documented to improve antibiotic efficacy, but the relevant metabolic mechanisms require more studies. Here, we show that glutamate potentiates aminoglycoside antibiotics, resulting in improved elimination of antibiotic-resistant pathogens. When exploring the metabolic flux of glutamate, it was found that the enzymes that link the phosphoenolpyruvate (PEP)-pyruvate-AcCoA pathway to the TCA cycle were key players in this increased efficacy. Together, the PEP-pyruvate-AcCoA pathway and TCA cycle can be considered the pyruvate cycle (P cycle). Our results show that inhibition or gene depletion of the enzymes in the P cycle shut down the TCA cycle even in the presence of excess carbon sources, and that the P cycle operates routinely as a general mechanism for energy production and regulation in Escherichia coli and Edwardsiella tarda These findings address metabolic mechanisms of metabolite-induced potentiation and fundamental questions about bacterial biochemistry and energy metabolism.

  8. Purification, crystallization and preliminary X-ray analysis of aminoglycoside-2′′-phosphotransferase-Ic [APH(2′′)-Ic] from Enterococcus gallinarum

    International Nuclear Information System (INIS)

    Byrnes, Laura J.; Badarau, Adriana; Vakulenko, Sergei B.; Smith, Clyde A.

    2008-01-01

    APH(2′′)-Ic is an enzyme that is responsible for high-level gentamicin resistance in E. gallinarum isolates. Crystals of the wild-type enzyme and three mutants have been prepared and a complete X-ray diffraction data set was collected to 2.15 Å resolution from an F108L crystal. Bacterial resistance to aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, aminoglycoside-2′′-phosphotransferase-Ic [APH(2′′)-Ic] from Enterococcus gallinarum, has been cloned and the wild-type protein (comprising 308 amino-acid residues) and three mutants that showed elevated minimum inhibitory concentrations towards gentamicin (F108L, H258L and a double mutant F108L/H258L) were expressed in Escherichia coli and subsequently purified. All APH(2′′)-Ic variants were crystallized in the presence of 14–20%(w/v) PEG 4000, 0.25 M MgCl 2 , 0.1 M Tris–HCl pH 8.5 and 1 mM Mg 2 GTP. The crystals belong to the monoclinic space group C2, with one molecule in the asymmetric unit. The approximate unit-cell parameters are a = 82.4, b = 54.2, c = 77.0 Å, β = 108.8°. X-ray diffraction data were collected to approximately 2.15 Å resolution from an F108L crystal at beamline BL9-2 at SSRL, Stanford, California, USA

  9. Aminoglycoside-derived amphiphilic nanoparticles for molecular delivery.

    Science.gov (United States)

    Miryala, Bhavani; Godeshala, Sudhakar; Grandhi, Taraka Sai Pavan; Christensen, Matthew D; Tian, Yanqing; Rege, Kaushal

    2016-10-01

    The development of effective drug carriers can lead to improved outcomes in a variety of disease conditions. Aminoglycosides have been used as antibacterial therapeutics, and are attractive as monomers for the development of polymeric materials in various applications. Here, we describe the development of novel aminoglycoside-derived amphiphilic nanoparticles for drug delivery, with an eye towards ablation of cancer cells. The aminoglycoside paromomycin was first cross-linked with resorcinol diglycidyl ether leading to the formation of a poly (amino ether), PAE. PAE molecules were further derivatized with methoxy-terminated poly(ethylene glycol) or mPEG resulting in the formation of mPEG-PAE polymer, which self-assembled to form nanoparticles. Formation of the mPEG-PAE amphiphile was characterized using (1)H NMR, (13)C NMR, gel permeation chromatography (GPC) and FTIR spectroscopy. Self-assembly of the polymer into nanoparticles was characterized using dynamic light scattering, zeta potential analyses, atomic force microscopy (AFM) and the pyrene fluorescence assay. mPEG-PAE nanoparticles were able to carry significant amounts of doxorubicin (DOX), presumably by means of hydrophobic interactions between the drug and the core. Cell-based studies indicated that mPEG-PAE nanoparticles, loaded with doxorubicin, were able to induce significant loss in viabilities of PC3 human prostate cancer, MDA-MB-231 human breast cancer, and MB49 murine bladder cancer cells; empty nanoparticles resulted in negligible losses of cell viability under the conditions investigated. Taken together, our results indicate that the mPEG-PAE nanoparticle platform is attractive for drug delivery in different applications, including cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Purification, crystallization and preliminary X-ray analysis of Enterococcus faecium aminoglycoside-2′′-phosphotransferase-Ib [APH(2′′)-Ib

    International Nuclear Information System (INIS)

    Walanj, Rupa; Young, Paul; Baker, Heather M.; Baker, Edward N.; Metcalf, Peter; Chow, Joseph W.; Lerner, Stephen; Vakulenko, Sergei; Smith, Clyde A.

    2005-01-01

    APH(2′′)-Ib is an enzyme responsible for high-level gentamicin resistance in E. faecium isolates. Native crystals of this enzyme have been prepared and preliminary X-ray diffraction experiments have been undertaken. Bacterial resistance to the aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, APH(2′′)-Ib, has been cloned and the protein (comprising 299 amino-acid residues) expressed in Escherichia coli, purified and crystallized in the presence of 16%(w/v) PEG 3350 and gentamicin. The crystals belong to the monoclinic space group P2 1 , with approximate unit-cell parameters a = 79.7, b = 58.8, c = 81.4 Å, β = 98.4°, and preliminary X-ray diffraction analysis is consistent with the presence of two molecules in the asymmetric unit. Synchrotron diffraction data to approximately 2.65 Å resolution were collected from a native APH(2′′)-Ib crystal at beamline BL9-2 at SSRL (Stanford, CA, USA). Selenium-substituted crystals have also been produced and structure determination is proceeding

  11. Loss of Slc4a1b chloride/bicarbonate exchanger function protects mechanosensory hair cells from aminoglycoside damage in the zebrafish mutant persephone.

    Directory of Open Access Journals (Sweden)

    Dale W Hailey

    Full Text Available Mechanosensory hair cell death is a leading cause of hearing and balance disorders in the human population. Hair cells are remarkably sensitive to environmental insults such as excessive noise and exposure to some otherwise therapeutic drugs. However, individual responses to damaging agents can vary, in part due to genetic differences. We previously carried out a forward genetic screen using the zebrafish lateral line system to identify mutations that alter the response of larval hair cells to the antibiotic neomycin, one of a class of aminoglycoside compounds that cause hair cell death in humans. The persephone mutation confers resistance to aminoglycosides. 5 dpf homozygous persephone mutants are indistinguishable from wild-type siblings, but differ in their retention of lateral line hair cells upon exposure to neomycin. The mutation in persephone maps to the chloride/bicarbonate exchanger slc4a1b and introduces a single Ser-to-Phe substitution in zSlc4a1b. This mutation prevents delivery of the exchanger to the cell surface and abolishes the ability of the protein to import chloride across the plasma membrane. Loss of function of zSlc4a1b reduces hair cell death caused by exposure to the aminoglycosides neomycin, kanamycin, and gentamicin, and the chemotherapeutic drug cisplatin. Pharmacological block of anion transport with the disulfonic stilbene derivatives DIDS and SITS, or exposure to exogenous bicarbonate, also protects hair cells against damage. Both persephone mutant and DIDS-treated wild-type larvae show reduced uptake of labeled aminoglycosides. persephone mutants also show reduced FM1-43 uptake, indicating a potential impact on mechanotransduction-coupled activity in the mutant. We propose that tight regulation of the ionic environment of sensory hair cells, mediated by zSlc4a1b activity, is critical for their sensitivity to aminoglycoside antibiotics.

  12. Aminoglycoside Concentrations Required for Synergy with Carbapenems against Pseudomonas aeruginosa Determined via Mechanistic Studies and Modeling.

    Science.gov (United States)

    Yadav, Rajbharan; Bulitta, Jürgen B; Schneider, Elena K; Shin, Beom Soo; Velkov, Tony; Nation, Roger L; Landersdorfer, Cornelia B

    2017-12-01

    This study aimed to systematically identify the aminoglycoside concentrations required for synergy with a carbapenem and characterize the permeabilizing effect of aminoglycosides on the outer membrane of Pseudomonas aeruginosa Monotherapies and combinations of four aminoglycosides and three carbapenems were studied for activity against P. aeruginosa strain AH298-GFP in 48-h static-concentration time-kill studies (SCTK) (inoculum: 10 7.6 CFU/ml). The outer membrane-permeabilizing effect of tobramycin alone and in combination with imipenem was characterized via electron microscopy, confocal imaging, and the nitrocefin assay. A mechanism-based model (MBM) was developed to simultaneously describe the time course of bacterial killing and prevention of regrowth by imipenem combined with each of the four aminoglycosides. Notably, 0.25 mg/liter of tobramycin, which was inactive in monotherapy, achieved synergy (i.e., ≥2-log 10 more killing than the most active monotherapy at 24 h) combined with imipenem. Electron micrographs, confocal image analyses, and the nitrocefin uptake data showed distinct outer membrane damage by tobramycin, which was more extensive for the combination with imipenem. The MBM indicated that aminoglycosides enhanced the imipenem target site concentration up to 4.27-fold. Tobramycin was the most potent aminoglycoside to permeabilize the outer membrane; tobramycin (0.216 mg/liter), gentamicin (0.739 mg/liter), amikacin (1.70 mg/liter), or streptomycin (5.19 mg/liter) was required for half-maximal permeabilization. In summary, our SCTK, mechanistic studies and MBM indicated that tobramycin was highly synergistic and displayed the maximum outer membrane disruption potential among the tested aminoglycosides. These findings support the optimization of highly promising antibiotic combination dosage regimens for critically ill patients. Copyright © 2017 American Society for Microbiology.

  13. Synthesis of Netilmicin and Apramycin Derivatives for the Treatment of Multidrug-Resistant Infectious Diseases

    Science.gov (United States)

    Sonousi, Amr

    The ever-growing bacterial resistance to existing antibiotics is alarming to humanity. Many researchers decided to revisit aminoglycosides with renewed emphasis on chemical modification as they have long been used as highly potent antibiotics for treating severe bacterial infections. The bactericidal effect of aminoglycosides is mainly due to protein synthesis inhibition by binding to the A-site of the bacterial ribosomes. However, the high potency and the broad spectrum of aminoglycosides has been outweighed by their side effects, especially ototoxicity, and by the resistance of pathogens. The goal of this research was the modification of existing aminoglycosides to develop derivatives which are less toxic and that evade resistance. The chapters in the thesis discuss the chemical synthesis as well as the biological evaluation of the newly synthesized analogs. This study has focused on the modification of aminoglycosides netilmicin and apramycin. Chapter one introduces the MDR bacterial infection problem and its influence. Chapter one also introduces the aminoglycosides elaborating their history, classifications, and their mechanism of action. The resistance mechanisms against aminoglycosides and their adverse effects, as well as the ways to prevent them are briefly explained. Chapter two discusses modifications of netilmicin at the 4'-position conducted with a view to reducing the ototoxicity but not the antibiotic activity, as was previously done in the 4,5-series with paromomycin. The antibacterial activity and antiribosomal activity of the six netilmicin derivatives synthesized were determined. The 4'-position is more sensitive to modification in 4,6-series than in the 4,5-series to the extent that such modifications are ineffective. Chapter two also highlights the use of phenyl triazenes as selective protecting groups for secondary amines in the presence of primary amines. Several polyamine substrates were selectively protected as phenyl triazenes, and primary

  14. Simple measurement of isepamicin, a new aminoglycoside antibiotic, in guinea pig and human plasma, using high-performance liquid chromatography with ultraviolet detection

    International Nuclear Information System (INIS)

    Dionisotti, S.; Bamonte, F.; Scaglione, F.; Ongini, E.

    1991-01-01

    Isepamicin, the 1-N-(S-alpha-hydroxy-beta-aminopropionyl) derivative of gentamicin B, is a new aminoglycoside antibiotic, which not only has most of the properties of amikacin but also is effective against several amikacin-resistant strains of bacteria. The drug was assayed in guinea-pig and human plasma with a high-performance liquid chromatographic procedure using precolumn derivatization with 1-fluoro-2,4-dinitrobenzene and ultraviolet detection. Linearity was established over the range 0.5-40 micrograms/ml using 50 microliters of plasma. Accuracy has a mean relative error of less than 3% and precision a mean coefficient of variation of 5%. Isepamicin was determined without interference from plasma constituents or other drugs commonly prescribed during aminoglycoside therapy. This procedure correlates well with radioimmunoassay and can be used either in experimental studies or therapeutic monitoring of plasma levels

  15. Activity of some aminoglycoside antibiotics against true fungi, Phytophthora and Pythium species.

    Science.gov (United States)

    Lee, H B; Kim, Y; Kim, J C; Choi, G J; Park, S-H; Kim, C-J; Jung, H S

    2005-01-01

    To investigate the in vitro antifungal and antioomycete activities of some aminoglycosides against true fungi and Phytophthora and Pythium species and to evaluate the potential of the antibiotics against Phytophthora late blight on plants. Antifungal and antioomycete activities of aminoglycoside antibiotics (neomycin, paromomycin, ribostamycin and streptomycin) and a paromomycin-producing strain (Streptomyces sp. AMG-P1) against Phytophthora and Pythium species and 10 common fungi were measured in potato dextrose broth (PDB) and on seedlings in pots. Paromomycin was the most active against Phytophthora and Pythium species with a minimal inhibitory concentration of 1-10 microg ml(-1) in PDB, but displayed low to moderate activities towards other common fungi at the same concentration. Paromomycin also showed potent in vivo activity against red pepper and tomato late blight diseases with 80 and 99% control value, respectively, at 100 microg ml(-1). In addition, culture broth of Streptomyces sp. AMG-P1 as a paromomycin producer exhibited high in vivo activity against late blight at 500 microg freeze-dried weight per millilitre. Among tested aminoglycoside antibiotics, paromomycin was the most active against oomycetes both in vitro and in vivo. Data from this study show that aminoglycoside antibiotics have in vitro and in vivo activities against oomycetes, suggesting that Streptomyces sp. AMG-P1 may be used as a biocontrol agent against oomycete diseases.

  16. Heparin interferes with the radioenzymatic and homogeneous enzyme immunoassays for aminoglycosides

    International Nuclear Information System (INIS)

    Krogstad, D.J.; Granich, G.G.; Murray, P.R.; Pfaller, M.A.; Valdes, R.

    1981-01-01

    Heparin interferes with measurement of aminoglycosides in serum by biological, radioenzymatic, and homogeneous enzyme immunoassay techniques, but not with radioimmunoassay. At concentrations greater than or equal to 10 5 and greater than or equal to 3 X 10 6 USP units/L, respectively, it interferes with the radioenzymatic assay by inhibiting the gentamicin 3-acetyltransferase and kanamycin 6'-acetyltransferase enzymes used in the assay. It interferes with the homogeneous enzyme immunoassays for gentamicin and tobramycin (at concentrations greater than or equal to 10 5 and greater than or equal to10 4 USP units/L, respectively), but not with the commercially available homogeneous enzyme immunoassays for other drugs. Heparin interference with the homogeneous enzyme immunoassay for aminoglycosides requires both the heparin polyanion and glucose-6-phosphate dehydrogenase bound to a cationic aminoglycoside. This interference can be reproduced with dextran sulfate (but not dextran), and does not occur with free enzyme (glucose-6-phosphate dehydrogenase) alone. Heparin interference with these two assays and at concentrations that may be present in intravenous infusions or in seriously underfilled blood-collection tubes is described

  17. Dissemination of antibiotic resistance in methicillin-resistant Staphylococcus aureus and vancomycin-resistant S aureus strains isolated from hospital effluents.

    Science.gov (United States)

    Mandal, Santi M; Ghosh, Ananta K; Pati, Bikas R

    2015-12-01

    Vancomycin-resistant Staphylococcus aureus (VRSA) and methicillin-resistant S aureus (MRSA) strains were examined in hospital effluents. Most S aureus strains are resistant to methicillin (MRSA), followed by tetracycline. Approximately 15% of MRSA strains are also resistant to vancomycin (VRSA). All VRSA strains developed a VanR/VanS-regulated 2-component system of VanA-type resistance in their genome. Results indicate that there is a possibility of developing resistance to aminoglycosides by VRSA strains in the near future. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  18. A Novel 6'-N-Aminoglycoside Acetyltransferase, AAC(6')-Ial, from a Clinical Isolate of Serratia marcescens.

    Science.gov (United States)

    Tada, Tatsuya; Miyoshi-Akiyama, Tohru; Shimada, Kayo; Dahal, Rajan K; Mishra, Shyam K; Ohara, Hiroshi; Kirikae, Teruo; Pokhrel, Bharat M

    2016-03-01

    Serratia marcescens IOMTU115 has a novel 6'-N-aminoglycoside acetyltransferase-encoding gene, aac(6')-Ial. The encoded protein AAC(6')-Ial has 146 amino acids, with 91.8% identity to the amino acid sequence of AAC(6')-Ic in S. marcescens SM16 and 97.3% identity to the amino acid sequence of AAC(6')-Iap in S. marcescens WW4. The minimum inhibitory concentrations of aminoglycosides for Escherichia coli expressing AAC(6')-Ial were similar to those for E. coli expressing AAC(6')-Ic or AAC(6')-Iap. Thin-layer chromatography showed that AAC(6')-Ial, AAC(6')-Ic, or AAC(6')-Iap acetylated all the aminoglycosides tested, except for apramycin, gentamicin, and lividomycin. Kinetics assays revealed that AAC(6')-Ial is a functional acetyltransferase against aminoglycosides. The aac(6')-Ial gene was located on chromosomal DNA.

  19. Mosaic Structure of a Multiple-Drug-Resistant, Conjugative Plasmid from Campylobacter jejuni

    National Research Council Canada - National Science Library

    Nirdnoy, Warawadee; Mason, Carl J; Guerry, Patricia

    2005-01-01

    ..., where it apparently integrated into the chromosome and expressed high-level resistance to multiple aminoglycoside antibiotics. This work provides new information about both the nature of drug resistance in C...

  20. Purification, crystallization and preliminary X-ray analysis of Enterococcus faecium aminoglycoside-2′′-phosphotransferase-Ib [APH(2′′)-Ib

    Energy Technology Data Exchange (ETDEWEB)

    Walanj, Rupa; Young, Paul; Baker, Heather M.; Baker, Edward N.; Metcalf, Peter [Laboratory of Structural Biology, School of Biological Sciences, University of Auckland, Auckland (New Zealand); Chow, Joseph W.; Lerner, Stephen [Division of Infectious Diseases, Wayne State University School of Medicine and VA Medical Center, Detroit, Michigan 48201 (United States); Vakulenko, Sergei [Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Smith, Clyde A., E-mail: csmith@slac.stanford.edu [Stanford Synchrotron Radiation Laboratory, Stanford University, Menlo Park, CA 94025 (United States); Laboratory of Structural Biology, School of Biological Sciences, University of Auckland, Auckland (New Zealand)

    2005-04-01

    APH(2′′)-Ib is an enzyme responsible for high-level gentamicin resistance in E. faecium isolates. Native crystals of this enzyme have been prepared and preliminary X-ray diffraction experiments have been undertaken. Bacterial resistance to the aminoglycoside antibiotics is primarily the result of deactivation of the drugs. Three families of enzymes are responsible for this activity, with one such family being the aminoglycoside phosphotransferases (APHs). The gene encoding one of these enzymes, APH(2′′)-Ib, has been cloned and the protein (comprising 299 amino-acid residues) expressed in Escherichia coli, purified and crystallized in the presence of 16%(w/v) PEG 3350 and gentamicin. The crystals belong to the monoclinic space group P2{sub 1}, with approximate unit-cell parameters a = 79.7, b = 58.8, c = 81.4 Å, β = 98.4°, and preliminary X-ray diffraction analysis is consistent with the presence of two molecules in the asymmetric unit. Synchrotron diffraction data to approximately 2.65 Å resolution were collected from a native APH(2′′)-Ib crystal at beamline BL9-2 at SSRL (Stanford, CA, USA). Selenium-substituted crystals have also been produced and structure determination is proceeding.

  1. Coexistence of blaOXA-23 with armA in quinolone-resistant Acinetobacter baumannii from a Chinese university hospital.

    Science.gov (United States)

    Shen, Min; Luan, Guangxin; Wang, Yanhong; Chang, Yaowen; Zhang, Chi; Yang, Jingni; Deng, Shanshan; Ling, Baodong; Jia, Xu

    2016-03-01

    A total of 101 Acinetobacter baumannii isolates were collected to determine the mechanisms of quinolone resistance and investigate the occurrence of carbapenem and high-level aminoglycoside resistance genes among quinolone-resistant strains. Among 77 quinolone-resistant A. baumannii harbored mutations of gyrA and parC, 41 isolates, which belonged to European clone II, had resistance to aminoglycosides and carbapenems due to the expression of armA and acquisition of blaOXA-23. Most of sequence type belonged to clonal complex 92. These results suggested hospital dissemination of multidrug-resistant A. baumannii carrying blaOXA-23, armA, and mutations of quinolone resistance-determining regions in western China. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Natural bizbenzoquinoline derivatives protect zebrafish lateral line sensory hair cells from aminoglycoside toxicity

    Directory of Open Access Journals (Sweden)

    Matthew eKruger

    2016-03-01

    Full Text Available Moderate to severe hearing loss affects 360 million people worldwide and most often results from damage to sensory hair cells. Hair cell damage can result from aging, genetic mutations, excess noise exposure, and certain medications including aminoglycoside antibiotics. Aminoglycosides are effective at treating infections associated with cystic fibrosis and other life-threatening conditions such as sepsis, but cause hearing loss in 20-30% of patients. It is therefore imperative to develop new therapies to combat hearing loss and allow safe use of these potent antibiotics. We approach this drug discovery question using the larval zebrafish lateral line because zebrafish hair cells are structurally and functionally similar to mammalian inner ear hair cells and respond similarly to toxins. We screened a library of 502 natural compounds in order to identify novel hair cell protectants. Our screen identified four bisbenzylisoquinoline derivatives: berbamine, E6 berbamine, hernandezine, and isotetrandrine, each of which robustly protected hair cells from aminoglycoside-induced damage. Using fluorescence microscopy and electrophysiology, we demonstrated that the natural compounds confer protection by reducing antibiotic uptake into hair cells and showed that hair cells remain functional during and after incubation in E6 berbamine. We also determined that these natural compounds do not reduce antibiotic efficacy. Together, these natural compounds represent a novel source of possible otoprotective drugs that may offer therapeutic options for patients receiving aminoglycoside treatment.

  3. Structural Studies of Bacterial Enzymes and their Relation to Antibiotic Resistance Mechanisms - Final Paper

    Energy Technology Data Exchange (ETDEWEB)

    Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-27

    By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β- lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes

  4. Molecular characterization of a novel cryptic virus infecting pigeonpea plants.

    Directory of Open Access Journals (Sweden)

    Surender Kumar

    Full Text Available A new member of the genus Deltapartitivirus was identified containing three dsRNAs with an estimated size of 1.71, 1.49 and 1.43 kb. The dsRNAs were extracted from symptomless pigeonpea [Cajanus cajan (L. Millspaugh] plants cv. Erra Kandulu. This new virus with 4.64 kb genome was tentatively named Arhar cryptic virus-1 (ArCV-1. The genomic RNAs were amplified and characterized by sequence independent single primer amplification. The dsRNAs shared a highly conserved 16 nt 5' non-coding region (5'-GATAATGATCCAAGGA-3'. The largest dsRNA (dsRNA-1 was identified as the viral RNA dependent RNA polymerase (replicase, predicted to encode a putative 55.34 kDa protein (P1. The two other smaller dsRNAs (dsRNA-2 and dsRNA-3 predicted to encode for putative capsid proteins of 38.50kDa (P2 and 38.51kDa (P3, respectively. Phylogenetic analysis indicated that ArCV-1 formed a clade together with Fragaria chiloensis cryptic virus, Rosa multiflora cryptic virus and Rose cryptic virus-1, indicating that ArCV-1 could be a new member of the genus Deltapartitivirus. ArCV-1 3Dpol structure revealed several interesting features. The 3Dpol in its full-length shares structural similarities with members of the family Caliciviridaeand family Picornaviridae. In addition, fourth dsRNA molecule (dsRNA-2A, not related to ArCV-1 genome, was found in the same plant tissue. The dsRNA-2A (1.6 kb encodes a protein (P4, with a predicted size of 44.5 kDa. P4 shares similarity with coat protein genes of several cryptic viruses, in particular the bipartite cryptic viruses including Raphanus sativus cryptic virus-3. This is the first report of occurrence of a cryptic virus in pigeonpea plants.

  5. Low Prevalence of Carbapenem-Resistant Bacteria in River Water: Resistance Is Mostly Related to Intrinsic Mechanisms.

    Science.gov (United States)

    Tacão, Marta; Correia, António; Henriques, Isabel S

    2015-10-01

    Carbapenems are last-resort antibiotics to handle serious infections caused by multiresistant bacteria. The incidence of resistance to these antibiotics has been increasing and new resistance mechanisms have emerged. The dissemination of carbapenem resistance in the environment has been overlooked. The main goal of this research was to assess the prevalence and diversity of carbapenem-resistant bacteria in riverine ecosystems. The presence of frequently reported carbapenemase-encoding genes was inspected. The proportion of imipenem-resistant bacteria was on average 2.24 CFU/ml. Imipenem-resistant strains (n=110) were identified as Pseudomonas spp., Stenotrophomonas maltophilia, Aeromonas spp., Chromobacterium haemolyticum, Shewanella xiamenensis, and members of Enterobacteriaceae. Carbapenem-resistant bacteria were highly resistant to other beta-lactams such as quinolones, aminoglycosides, chloramphenicol, tetracyclines, and sulfamethoxazole/trimethoprim. Carbapenem resistance was mostly associated with intrinsically resistant bacteria. As intrinsic resistance mechanisms, we have identified the blaCphA gene in 77.3% of Aeromonas spp., blaL1 in all S. maltophilia, and blaOXA-48-like in all S. xiamenensis. As acquired resistance mechanisms, we have detected the blaVIM-2 gene in six Pseudomonas spp. (5.45%). Integrons with gene cassettes encoding resistance to aminoglycosides (aacA and aacC genes), trimethoprim (dfrB1b), and carbapenems (blaVIM-2) were found in Pseudomonas spp. Results suggest that carbapenem resistance dissemination in riverine ecosystems is still at an early stage. Nevertheless, monitoring these aquatic compartments for the presence of resistance genes and its host organisms is essential to outline strategies to minimize resistance dissemination.

  6. Beneficial read-through of a USH1C nonsense mutation by designed aminoglycoside NB30 in the retina.

    Science.gov (United States)

    Goldmann, Tobias; Rebibo-Sabbah, Annie; Overlack, Nora; Nudelman, Igor; Belakhov, Valery; Baasov, Timor; Ben-Yosef, Tamar; Wolfrum, Uwe; Nagel-Wolfrum, Kerstin

    2010-12-01

    The human Usher syndrome (USH) is the most frequent cause of inherited combined deaf-blindness. USH is clinically and genetically heterogeneous, assigned to three clinical types. The most severe type is USH1, characterized by profound inner ear defects and retinitis pigmentosa. Thus far, no effective treatment for the ophthalmic component of USH exists. The p.R31X nonsense mutation in USH1C leads to a disease causing premature termination of gene translation. Here, we investigated the capability of the novel synthetic aminoglycoside NB30 for the translational read-through of the USH1C-p.R31X nonsense mutation as a retinal therapy option. Read-through of p.R31X by three commercial, clinically applied aminoglycosides and the synthetic derivative NB30 was validated in vitro, in cell culture, and in retinal explants. Restoration of harmonin functions was monitored in GST pull-downs (scaffold function) and by F-actin bundling analysis in HEK293T cells. Biocompatibility of aminoglycosides was determined in retinal explants by TUNEL assays. In vitro translation and analyses of transfected HEK293T cells revealed a dose-dependent read-through by all aminoglycosides. In addition, gentamicin, paromomycin, and NB30 induced read-through of p.R31X in mouse retinal explants. The read-through of p.R31X restored harmonin protein function. In contrast to all commercial aminoglycosides NB30 showed good biocompatibility. Commercial aminoglycosides and NB30 induced significant read-through of the USH1C-p.R31X nonsense mutation. However, the observed read-through efficiency, along with its significantly reduced toxicity and good biocompatibility, indicate that the novel derivate NB30 represents a better choice than commercial aminoglycosides in a read-through therapy of USH1C and other ocular diseases.

  7. The risks of concurrent treatment with tenofovir and aminoglycosides ...

    African Journals Online (AJOL)

    The risks of concurrent treatment with tenofovir and aminoglycosides in patients with HIV-associated tuberculosis. C Kenyon, N Wearne, R Burton, G Meintjes. Abstract. The South African public sector antiretroviral treatment (ART) guidelines have recently been changed to include tenofovir in the first-line regimen.1 ...

  8. Cryptic biodiversity and phylogeographic patterns of Seychellois Ligia isopods

    Directory of Open Access Journals (Sweden)

    Carlos A. Santamaria

    2017-10-01

    Full Text Available Ligia isopods are conspicuous inhabitants of rocky intertidal habitats exhibiting several biological traits that severely limit their dispersal potential. Their presence in patchy habitats and low vagility may lead to long term isolation, allopatric isolation and possible cryptic speciation. Indeed, various species of Ligia have been suggested to represent instead cryptic species complexes. Past studies; however, have largely focused in Eastern Pacific and Atlantic species of Ligia, leaving in doubt whether cryptic diversity occurs in other highly biodiverse areas. The Seychelles consists of 115 islands of different ages and geological origins spread across the western Indian Ocean. They are well known for their rich biodiversity with recent reports of cryptic species in terrestrial Seychellois organisms. Despite these studies, it is unclear whether coastal invertebrates from the Seychelles harbor any cryptic diversity. In this study, we examined patterns of genetic diversity and isolation within Ligia isopods across the Seychelles archipelago by characterizing individuals from locations across both inner and outer islands of the Seychelles using mitochondrial and nuclear markers. We report the presence of highly divergent lineages of independent origin. At Aldabra Atoll, we uncovered a lineage closely related to the Ligia vitiensis cryptic species complex. Within the inner islands of Cousine, Silhouette, and Mahé we detected the presence of two moderately divergent and geographically disjunct lineages most closely related to Ligia dentipes. Our findings suggest that the Seychelles may harbor at least three novel species of Ligia in need of description and that these species may have originated independently.

  9. Diversity of enterococcal species and characterization of high-level aminoglycoside resistant enterococci of samples of wastewater and surface water in Tunisia.

    Science.gov (United States)

    Ben Said, Leila; Klibi, Naouel; Lozano, Carmen; Dziri, Raoudha; Ben Slama, Karim; Boudabous, Abdellatif; Torres, Carmen

    2015-10-15

    One hundred-fourteen samples of wastewater (n=64) and surface-water (n=50) were inoculated in Slanetz-Bartley agar plates supplemented or not with gentamicin (SB-Gen and SB plates, respectively) for enterococci recovery. Enterococci were obtained from 75% of tested samples in SB media (72% in wastewater; 78% in surface-water), and 85 enterococcal isolates (one/positive-sample) were obtained. Enterococcus faecium was the most prevalent species (63.5%), followed by Enterococcus faecalis (20%), Enterococcus hirae (9.4%), Enterococcus casseliflavus (4.7%), and Enterococcus gallinarum/Enterococcus durans (2.4%). Antibiotic resistance detected among these enterococci was as follows [percentage/detected gene (number isolates)]: kanamycin [29%/aph(3')-IIIa (n=22)], streptomycin [8%/ant(6)-Ia (n=4)], erythromycin [44%/erm(B) (n=34)], tetracycline [18%/tet(M) (n=6)/tet(M)-tet(L) (n=9)], chloramphenicol [2%/cat(A) (n=1)], ciprofloxacin [7%] and trimethoprim-sulfamethoxazole [94%]. High-level-gentamicin resistant (HLR-G) enterococci were recovered from 15 samples in SB-Gen or SB plates [12/64 samples of wastewater (19%) and 3/50 samples of surface-water (6%)]; HLR-G isolates were identified as E. faecium (n=7), E. faecalis (n=6), and E. casseliflavus (n=2). These HLR-G enterococci carried the aac(6')-Ie-aph(2")-Ia and erm(B) genes, in addition to aph(3')-IIIa (n=10), ant(6)-Ia (n=9), tet(M) (n=13), tet(L) (n=8) and cat(A) genes (n=2). Three HLR-G enterococci carried the esp virulence gene. Sequence-types detected among HLR-G enterococci were as follows: E. faecalis (ST480, ST314, ST202, ST55, and the new ones ST531 and ST532) and E. faecium (ST327, ST12, ST296, and the new ones ST985 and ST986). Thirty-two different PFGE patterns were detected among 36 high-level-aminoglycoside-resistant enterococci recovered in water samples. Diverse genetic lineages of HLR-G enterococci were detected in wastewater and surface-water in Tunisia. Water can represent an important source for the

  10. Antimicrobial sensitivity and frequency of DRUG resistance among bacterial strains isolated from cancer patients

    International Nuclear Information System (INIS)

    Faiz, M.; Bashir, T.

    2004-01-01

    Blood stream infections (bacteremia) is potentially life threatening. Concomitant with a change in the incidence and epidemiology of infecting organisms, there has been an increase in resistance to many antibiotic compounds. The widespread emergence of resistance among bacterial pathogens has an impact on our ability to treat patients effectively. The changing spectrum of microbial pathogens and widespread emergence of microbial resistance to antibiotic drugs has emphasized the need to monitor the prevalence of resistance in these strains. In the present study frequency of isolation of clinically significant bacteria and their susceptibility and resistance pattern against a wide range of antimicrobial drugs from positive blood cultures collected during 2001-2003 was studied. A total of 102 consecutive isolates were found with 63% gram positive and 44% gram negative strains. The dominating pathogens were Staphylococcus aureus (51%), Streptococci (31%), Pseudomonas (40%), Proteus (13%), Klebsiella (13%). The isolated strains were tested against a wide range of antibiotics belonging to cephalosporins, aminoglycosides and quinolone derivative group by disk diffusion method. It has been observed that isolated strains among gram positive and negative strains showed different level of resistance against aminoglycosides and cephalosporin group of antibiotics with gram positives showing highest number and frequency of resistance against aminoglycosides (40-50%) and cephalosporins.(35-45%) whereas cephalosporins were found to be more effective against gram negatives with low frequency of resistant strains. Cabapenem and quinolone derivative drugs were found to be most effective among other groups in both gram positive and negative strains with 23-41% strains found sensitive to these two drugs. The frequency of sensitive strains against aminoglycoside and cephalosporin in gram negative and gram positive strains were found to be decreasing yearwise with a trend towards an

  11. Cryptic Sebastes norvegicus species in Greenland waters revealed by microsatellites

    DEFF Research Database (Denmark)

    Saha, Atal; Hauser, Lorenz; Hedeholm, Rasmus

    2017-01-01

    Identification of cryptic species can have profound implications in fishery management, conservation and biodiversity contexts. In the North Atlantic, the genus Sebastes is currently represented by four species, although additional cryptic species have been assumed. The connectivity of the gene...

  12. Andrographolide: A potent antituberculosis compound that targets Aminoglycoside 2'-N-acetyltransferase in Mycobacterium tuberculosis.

    Science.gov (United States)

    Prabu, Amudha; Hassan, Sameer; Prabuseenivasan; Shainaba, A S; Hanna, L E; Kumar, Vanaja

    2015-09-01

    Tuberculosis (TB) still remains a major challenging infectious disease. The increased rate of emergence of multi-drug resistant and extensively-drug resistant strains of the organism has further complicated the situation, resulting in an urgent need for new anti-TB drugs. Antimycobacterial activity of Andrographis paniculata was evaluated using a rapid LRP assay and the probable targets were identified by docking analysis. The methanolic extract of A. paniculata showed maximum antimycobacterial activity at 250μg/ml against all the tested strains of M. tuberculosis (H37Rv, MDR, and drug sensitive). Based on bioassay guided fractionation, andrographolide was identified as the potent molecule. With the docking analysis, both ICDH (Isocitrate Dehydrogenase) and AAC (Aminoglycoside 2'-N-acetyltransferase) were predicted as targets of andrographolide in M. tuberculosis. Molecular simulation revealed that, ICDH showed low binding affinity to andrographolide. However, for AAC, the andrographolide was observed to be well within the active site after 10ns of molecular simulation. This suggests that ACC (PDB ID 1M4I) could be the probable target for andrographolide. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Potentiation of aminoglycoside antibiotic activity using the body fat from the snake Boa constrictor

    Directory of Open Access Journals (Sweden)

    Felipe S. Ferreira

    2011-05-01

    Full Text Available Boa constrictor is widely used in traditional communities in many different folk remedies and products derived from it are sold in public markets throughout northeastern Brazil and as its body fat has many different therapeutic indications as a folk remedy. The present work evaluates the antibacterial activity of the body fat from the snake Boa constrictor when employed either alone or in combination with antibiotics and discusses the ecological implications of the use of this traditional remedy. Oil (OBC was extracted from body fat located in the ventral region of B. constrictor using hexane as a solvent. The antibacterial activity of OBC was tested against standard as well as multi-resistant lines, either alone and in combination with antibiotics. OBC did not demonstrate any relevant antibacterial activity against standard or multidrug-resistant bacterial strains. OBC showed synergistic activity when combined with the aminoglycoside antibiotics. Our results indicate that the body fat of Boa constrictor does not possess bactericidal activity, from the clinical point of view, but when combined with an antibiotic, the fat demonstrated a significant synergistic activity.

  14. Potentiation of aminoglycoside antibiotic activity using the body fat from the snake Boa constrictor

    Directory of Open Access Journals (Sweden)

    Felipe S. Ferreira

    2011-06-01

    Full Text Available Boa constrictor is widely used in traditional communities in many different folk remedies and products derived from it are sold in public markets throughout northeastern Brazil and as its body fat has many different therapeutic indications as a folk remedy. The present work evaluates the antibacterial activity of the body fat from the snake Boa constrictor when employed either alone or in combination with antibiotics and discusses the ecological implications of the use of this traditional remedy. Oil (OBC was extracted from body fat located in the ventral region of B. constrictor using hexane as a solvent. The antibacterial activity of OBC was tested against standard as well as multi-resistant lines, either alone and in combination with antibiotics. OBC did not demonstrate any relevant antibacterial activity against standard or multidrug-resistant bacterial strains. OBC showed synergistic activity when combined with the aminoglycoside antibiotics. Our results indicate that the body fat of Boa constrictor does not possess bactericidal activity, from the clinical point of view, but when combined with an antibiotic, the fat demonstrated a significant synergistic activity.

  15. Determination of aminoglycoside antibiotics using complex compounds of chromotropic acid bisazoderivatives with rare earth ions

    International Nuclear Information System (INIS)

    Alykov, N.M.

    1981-01-01

    Studies of complex formation of bisazo derivatives of chromotropic acid with rare earth ions and aminoglycoside antibiotics have made it possible to choose carboxyarsenazo, orthanyl R and carboxynitrazo as highly sensitive reagents for determining aminoglycoside antibiotics. Conditions have been found for the formation of precipitates of different-ligand complexes containing rare earth ions, bisazo derivatives of chromotropic acid and aminogylcoside antibiotics. A procedure has been worked out of determining the antibiotics in biological samples with carboxyarsenazo [ru

  16. Burkholderia pseudomallei isolates from Sarawak, Malaysian Borneo, are predominantly susceptible to aminoglycosides and macrolides.

    Science.gov (United States)

    Podin, Yuwana; Sarovich, Derek S; Price, Erin P; Kaestli, Mirjam; Mayo, Mark; Hii, KingChing; Ngian, Hieung; Wong, SeeChang; Wong, IngTien; Wong, JinShyan; Mohan, Anand; Ooi, MongHow; Fam, TemLom; Wong, Jack; Tuanyok, Apichai; Keim, Paul; Giffard, Philip M; Currie, Bart J

    2014-01-01

    Melioidosis is a potentially fatal disease caused by the saprophytic bacterium Burkholderia pseudomallei. Resistance to gentamicin is generally a hallmark of B. pseudomallei, and gentamicin is a selective agent in media used for diagnosis of melioidosis. In this study, we determined the prevalence and mechanism of gentamicin susceptibility found in B. pseudomallei isolates from Sarawak, Malaysian Borneo. We performed multilocus sequence typing and antibiotic susceptibility testing on 44 B. pseudomallei clinical isolates from melioidosis patients in Sarawak district hospitals. Whole-genome sequencing was used to identify the mechanism of gentamicin susceptibility. A novel allelic-specific PCR was designed to differentiate gentamicin-sensitive isolates from wild-type B. pseudomallei. A reversion assay was performed to confirm the involvement of this mechanism in gentamicin susceptibility. A substantial proportion (86%) of B. pseudomallei clinical isolates in Sarawak, Malaysian Borneo, were found to be susceptible to the aminoglycoside gentamicin, a rare occurrence in other regions where B. pseudomallei is endemic. Gentamicin sensitivity was restricted to genetically related strains belonging to sequence type 881 or its single-locus variant, sequence type 997. Whole-genome sequencing identified a novel nonsynonymous mutation within amrB, encoding an essential component of the AmrAB-OprA multidrug efflux pump. We confirmed the role of this mutation in conferring aminoglycoside and macrolide sensitivity by reversion of this mutation to the wild-type sequence. Our study demonstrates that alternative B. pseudomallei selective media without gentamicin are needed for accurate melioidosis laboratory diagnosis in Sarawak. This finding may also have implications for environmental sampling of other locations to test for B. pseudomallei endemicity.

  17. Stimulation of diesel degradation and biosurfactant production by aminoglycosides in a novel oil-degrading bacterium Pseudomonas luteola PRO23

    Directory of Open Access Journals (Sweden)

    Atanasković Iva M.

    2016-01-01

    Full Text Available Bioremediation is promising technology for dealing with oil hydrocarbons contamination. In this research growth kinetics and oil biodegradation efficiency of Pseudomonas luteola PRO23, isolated from crude oil-contaminated soil samples, were investigated under different concentrations (5, 10 and 20 g/L of light and heavy crude oil. More efficient biodegradation and more rapid adaptation and cell growth were obtained in conditions with light oil. The 5 to 10 g/L upgrade of light oil concentration stimulated the microbial growth and the biodegradation efficiency. Further upgrade of light oil concentration and the upgrade of heavy oil concentration both inhibited the microbial growth, as well as biodegradation process. Aminoglycosides stimulated biosurfactant production in P. luteola in the range of sub-inhibitory concentrations (0.3125, 0.625 μg/mL. Aminoglycosides also induced biofilm formation. The production of biosurfactants was the most intense during lag phase and continues until stationary phase. Aminoglycosides also induced changes in P. luteola growth kinetics. In the presence of aminoglycosides this strain degraded 82% of diesel for 96 h. These results indicated that Pseudomonas luteola PRO23 potentially can be used in bioremediation of crude oil-contaminated environments and that aminoglycosides could stimulate this process. [Projekat Ministarstva nauke Republike Srbije, br. TR31080

  18. A low-barrier hydrogen bond mediates antibiotic resistance in a noncanonical catalytic triad

    Science.gov (United States)

    2018-01-01

    One group of enzymes that confer resistance to aminoglycoside antibiotics through covalent modification belongs to the GCN5-related N-acetyltransferase (GNAT) superfamily. We show how a unique GNAT subfamily member uses a previously unidentified noncanonical catalytic triad, consisting of a glutamic acid, a histidine, and the antibiotic substrate itself, which acts as a nucleophile and attacks the acetyl donor molecule. Neutron diffraction studies allow for unambiguous identification of a low-barrier hydrogen bond, predicted in canonical catalytic triads to increase basicity of the histidine. This work highlights the role of this unique catalytic triad in mediating antibiotic resistance while providing new insights into the design of the next generation of aminoglycosides. PMID:29632894

  19. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

    Energy Technology Data Exchange (ETDEWEB)

    Hoelzel, Christina S., E-mail: Christina.Hoelzel@wzw.tum.de [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mueller, Christa [Institute for Agroecology, Organic Farming and Soil Protection, Bavarian State Research Center for Agriculture (LfL), Lange Point 12, 85354 Freising (Germany); Harms, Katrin S. [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mikolajewski, Sabine [Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Lange Point 4, 85354 Freising (Germany); Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany)

    2012-02-15

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  20. Determination of aminoglycoside antibiotics using an on-chip microfluidic device with chemiluminescence detection

    International Nuclear Information System (INIS)

    Sierra-Rodero, M.; Fernandez-Romero, J.M.; Gomez-Hens, A.

    2012-01-01

    We describe an on-chip microflow injection (μFI) approach for the determination of aminoglycoside antibiotics using chemiluminescence (CL) detection. The method is based on the inhibition of the Cu(II)-catalyzed CL reaction of luminol and hydrogen peroxide by the aminoglycosides due to the formation of a complex between the antibiotic and Cu(II). The main features of the method include small sample volumes and a fast response. Syringe pumps were used to insert the sample and the reagents into the microfluidic device. CL was collected using a fiber optic bundle connected to a luminescence detector. All instrumental, hydrodynamic and chemical variables involved in the system were optimized using neomycin as the aminoglycoside model. Inhibition is proportional to the concentration of the antibiotics. The dynamic ranges of the calibration graphs obtained for neomycin, streptomycin and amikacin are 0.3-3.3, 0.9-13.7, and 0.8-8.5 μmol L -1 , and the detection limits are 0.09, 0.28 and 0.24 μmol L -1 , respectively. The precision of the methods, expressed as relative standard deviation, is in the range from 0.8 to 5.0 %. The method was successfully applied to the determination of neomycin in water samples, with recoveries ranging from 80 to 120 %. (author)

  1. Readthrough of stop codons by use of aminoglycosides in cells from xeroderma pigmentosum group C patients.

    Science.gov (United States)

    Kuschal, Christiane; Khan, Sikandar G; Enk, Benedikt; DiGiovanna, John J; Kraemer, Kenneth H

    2015-04-01

    Readthrough of premature termination (stop) codons (PTC) is a new approach to treatment of genetic diseases. We recently reported that readthrough of PTC in cells from some xeroderma pigmentosum complementation group C (XP-C) patients could be achieved with the aminoglycosides geneticin or gentamicin. We found that the response depended on several factors including the PTC sequence, its location within the gene and the aminoglycoside used. Here, we extended these studies to investigate the effects of other aminoglycosides that are already on the market. We reasoned that topical treatment could deliver much higher concentrations of drug to the skin, the therapeutic target, and thus increase the therapeutic effect while reducing renal or ototoxicity in comparison with systemic treatment. Our prior clinical studies indicated that only a few percent of normal XPC expression was associated with mild clinical disease. We found minimal cell toxicity in the XP-C cells with several aminoglycosides. We found increased XPC mRNA expression in PTC-containing XP-C cells with G418, paromomycin, neomycin and kanamycin and increased XPC protein expression with G418. We conclude that in selected patients with XP, topical PTC therapy can be investigated as a method of personalized medicine to alleviate their cutaneous symptoms. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  2. Phylogeographic insights into cryptic glacial refugia.

    Science.gov (United States)

    Provan, Jim; Bennett, K D

    2008-10-01

    The glacial episodes of the Quaternary (2.6 million years ago-present) were a major factor in shaping the present-day distributions of extant flora and fauna, with expansions and contractions of the ice sheets rendering large areas uninhabitable for most species. Fossil records suggest that many species survived glacial maxima by retreating to refugia, usually at lower latitudes. Recently, phylogeographic studies have given support to the existence of previously unknown, or cryptic, refugia. Here we summarise many of these insights into the glacial histories of species in cryptic refugia gained through phylogeographic approaches. Understanding such refugia might be important as the Earth heads into another period of climate change, in terms of predicting the effects on species distribution and survival.

  3. Coenzyme Q10 protects hair cells against aminoglycoside.

    Directory of Open Access Journals (Sweden)

    Kazuma Sugahara

    Full Text Available It is well known that the production of free radicals is associated with sensory cell death induced by an aminoglycoside. Many researchers have reported that antioxidant reagents protect sensory cells in the inner ear, and coenzyme Q10 (CoQ10 is an antioxidant that is consumed as a health food in many countries. The purpose of this study was to investigate the role of CoQ10 in mammalian vestibular hair cell death induced by aminoglycoside. Cultured utricles of CBA/CaN mice were divided into three groups (control group, neomycin group, and neomycin + CoQ10 group. In the neomycin group, utricles were cultured with neomycin (1 mM to induce hair cell death. In the neomycin + CoQ10 group, utricles were cultured with neomycin and water-soluble CoQ10 (30-0.3 µM. Twenty-four hours after exposure to neomycin, the cultured tissues were fixed, and vestibular hair cells were labeled using an anti-calmodulin antibody. Significantly more hair cells survived in the neomycin + CoQ10 group than in the neomycin group. These data indicate that CoQ10 protects sensory hair cells against neomycin-induced death in the mammalian vestibular epithelium; therefore, CoQ10 may be useful as a protective drug in the inner ear.

  4. Is the addition of aminoglycosides to beta-lactams in cancer patients with febrile neutropenia needed?

    Science.gov (United States)

    Contreras, Valeria; Sepúlveda, Sebastián; Heredia, Ana

    2016-02-24

    It is still controversial if the combined use of beta-lactam antibiotics and aminoglycosides has advantages over broad-spectrum beta-lactam monotherapy for the empirical treatment of cancer patients with febrile neutropenia. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified three systematic reviews including 14 pertinent randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded the combination of beta-lactam antibiotics and aminoglycosides probably does not lead to a reduced mortality in febrile neutropenic cancer patients and it might increase nephrotoxicity.

  5. Antibiotic resistant Escherichia coli in southeastern Australian pig herds and implications for surveillance.

    Science.gov (United States)

    van Breda, L K; Dhungyel, O P; Ward, M P

    2018-02-01

    To investigate public health implications of antibiotics to control post-weaning scours, we surveyed 22 commercial pig herds in southeastern Australia. Fifty faecal samples per herd were collected from pre- and post-weaned piglets. Presumptive Escherichia coli isolates were confirmed by MALDI-TOF MS. Isolates (n = 325) were screened for susceptibility to 19 veterinary antibiotics using MIC broth microdilution. All 325 E. coli isolates underwent further testing against 27 antibiotics used in human medicine and were screened for ETEC adhesin and enterotoxin genes (F4 (K88), F5 (K99), F6 (987P), F18, F41, STa, STb, Stx2e and LT) by multiplex PCR. Isolates identified as phenotypically resistant to third-generation cephalosporin (3GC) and aminoglycoside antibiotics were screened by multiplex PCR/reverse line blot to detect common β-lactam and aminoglycosides resistance genes, confirmed by sequencing. Twenty (6.1%) of the E. coli isolates were resistant to 3GC antibiotics and 24 (7.4%) to the aminoglycoside antibiotic gentamicin. Genetic analysis revealed six different extended spectrum β-lactamase (ESBL) genes (blaCTX-M-1, -14, -15, -27, blaSHV-12 and blaCMY-2-like genes), four of which have not been previously reported in Australian pigs. Critically, the prevalence of 3GC resistance was higher in non-pathogenic (non-ETEC) isolates and those from clinically normal (non-diarrhoeal) samples. This highlights the importance of non-ETECE. coli as reservoirs of antimicrobial resistance genes in piglet pens. Antimicrobial resistance surveillance in pig production focused on diagnostic specimens from clinically-affected animals might be potentially misleading. We recommend that surveillance for emerging antimicrobial resistance such as to 3GC antibiotics should include clinically healthy pigs. © 2017 Blackwell Verlag GmbH.

  6. Cryptic Species Identification and Composition of Bemisia tabaci (Hemiptera: Aleyrodidae) Complex in Henan Province, China

    Science.gov (United States)

    Hu, Jian; Wang, Lun-Ji; Dong, Jun-Feng; Song, Yue-Qin; Sun, Hui-Zhong

    2017-01-01

    Abstract Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex, causing significant crop losses in China during the last decade. Although knowledge of cryptic species composition and dynamics within B. tabaci complex is critical for developing sustainable pest management strategies, limited information is available on this pest in the Henan province of China. A systematic survey of the cryptic species composition and distribution of B. tabaci complex in different locations of Henan province was conducted in 2012. The results of RAPD-PCR and the gene for the mitochondrial cytochrome oxidase subunit-1 (mtCOI) based phylogenetic relationships established using Bayesian method indicated there were four known cryptic species MEAM1, MED, Asia II 3, Asia II 9 and a new cryptic species named China 6 in Henan province. In the survey, the invasive cryptic species MED and MEAM1 were found to be predominant with wide spread distribution across the surveyed regions. On the contrary, the indigenous B. tabaci cryptic species including Asia II 3, Asia II 9 and China 6 remained with low prevalence in some surveyed regions. Cryptic species MEAM1 and MED have not completely displaced the native B. tabaci in Henan province. This current study for the first time unifies our knowledge of the diversity and distribution of B. tabaci across Henan province of China. PMID:28973577

  7. Unusual Complication of Multidrug Resistant Tuberculosis

    Directory of Open Access Journals (Sweden)

    Prerna Sharma

    2017-01-01

    Full Text Available Introduction. Capreomycin is a second-line drug often used for multidrug-resistant tuberculosis which can result in nephrotoxic effects similar to other aminoglycosides. We describe a case of capreomycin induced Bartter-like syndrome with hypocalcemic tetany. Case Report. 23-year-old female patient presented with carpopedal spasms and tingling sensations in hands. Patient was being treated with capreomycin for two months for tuberculosis. On further investigation, hypocalcemia, hyponatremia, hypomagnesemia, hypokalemia, and hypochloremic metabolic alkalosis were noted. Vitamin D and serum PTH levels were within normal limits. Hypercalciuria was confirmed by urine calcium/creatinine ratio. Calcium, potassium, and magnesium supplementation was given and capreomycin was discontinued. Electrolytes normalized in two days after cessation of capreomycin with no further abnormalities on repeat investigations. Discussion. Aminoglycosides can result in renal tubular dysfunction leading to Fanconi syndrome, Bartter syndrome, and distal tubular acidosis. Impaired mitochondrial function in the tubular cells has been hypothesized as the possible cause of these tubulopathies. Acquired Bartter-like syndrome phenotypically resembles autosomal dominant type 5 Bartter syndrome. Treatment consists of correction of electrolyte abnormalities, indomethacin, and potassium-sparing diuretics. Prompt diagnosis and treatment of severe dyselectrolytemia are warranted in patients on aminoglycoside therapy.

  8. Functional Characterization of Bacteria Isolated from Ancient Arctic Soil Exposes Diverse Resistance Mechanisms to Modern Antibiotics

    Science.gov (United States)

    Perron, Gabriel G.; Whyte, Lyle; Turnbaugh, Peter J.; Goordial, Jacqueline; Hanage, William P.; Dantas, Gautam; Desai, Michael M.

    2015-01-01

    Using functional metagenomics to study the resistomes of bacterial communities isolated from different layers of the Canadian high Arctic permafrost, we show that microbial communities harbored diverse resistance mechanisms at least 5,000 years ago. Among bacteria sampled from the ancient layers of a permafrost core, we isolated eight genes conferring clinical levels of resistance against aminoglycoside, β-lactam and tetracycline antibiotics that are naturally produced by microorganisms. Among these resistance genes, four also conferred resistance against amikacin, a modern semi-synthetic antibiotic that does not naturally occur in microorganisms. In bacteria sampled from the overlaying active layer, we isolated ten different genes conferring resistance to all six antibiotics tested in this study, including aminoglycoside, β-lactam and tetracycline variants that are naturally produced by microorganisms as well as semi-synthetic variants produced in the laboratory. On average, we found that resistance genes found in permafrost bacteria conferred lower levels of resistance against clinically relevant antibiotics than resistance genes sampled from the active layer. Our results demonstrate that antibiotic resistance genes were functionally diverse prior to the anthropogenic use of antibiotics, contributing to the evolution of natural reservoirs of resistance genes. PMID:25807523

  9. Clinical evaluation and mitochondrial DNA sequence analysis in two Chinese families with aminoglycoside-induced and non-syndromic hearing loss

    International Nuclear Information System (INIS)

    Zhao Lidong; Wang Qiuju; Qian Yaping; Li Ronghua; Cao Juayng; Hart, Laura Christine; Zhai Suoqiang; Han Dongyi; Young Wieyen; Guan Minxin

    2005-01-01

    We report here the clinical, genetic, and molecular characterization of two Chinese pedigrees with aminoglycoside-induced and non-syndromic hearing impairment. Clinical evaluation revealed the variable phenotype of hearing impairment including audiometric configuration in these subjects. Penetrances of hearing loss in BJ105 and BJ106 pedigrees are 67% and 33%, respectively. In particular, three of 10 affected matrilineal relatives of BJ105 pedigree had aminoglycoside-induced hearing loss, while seven affected matrilineal relatives in BJ105 pedigree and six affected matrilineal relatives in BJ106 pedigree did not have a history of exposure to aminoglycosides. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the identical homoplasmic A1555G mutation and distinct sets of mtDNA variants belonging to haplogroups F3 and M7b. These variants showed no evolutionary conservation, implying that mitochondrial haplotype may not play a significant role in the phenotypic expression of the A1555G mutation in these Chinese pedigrees. However, aminoglycosides and nuclear backgrounds appear to be major modifier factors for the phenotypic manifestation of the A1555G mutation in these Chinese families

  10. Cryptic Species Identification and Composition of Bemisia tabaci (Hemiptera: Aleyrodidae) Complex in Henan Province, China.

    Science.gov (United States)

    Jiu, Min; Hu, Jian; Wang, Lun-Ji; Dong, Jun-Feng; Song, Yue-Qin; Sun, Hui-Zhong

    2017-05-01

    Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex, causing significant crop losses in China during the last decade. Although knowledge of cryptic species composition and dynamics within B. tabaci complex is critical for developing sustainable pest management strategies, limited information is available on this pest in the Henan province of China. A systematic survey of the cryptic species composition and distribution of B. tabaci complex in different locations of Henan province was conducted in 2012. The results of RAPD-PCR and the gene for the mitochondrial cytochrome oxidase subunit-1 (mtCOI) based phylogenetic relationships established using Bayesian method indicated there were four known cryptic species MEAM1, MED, Asia II 3, Asia II 9 and a new cryptic species named China 6 in Henan province. In the survey, the invasive cryptic species MED and MEAM1 were found to be predominant with wide spread distribution across the surveyed regions. On the contrary, the indigenous B. tabaci cryptic species including Asia II 3, Asia II 9 and China 6 remained with low prevalence in some surveyed regions. Cryptic species MEAM1 and MED have not completely displaced the native B. tabaci in Henan province. This current study for the first time unifies our knowledge of the diversity and distribution of B. tabaci across Henan province of China. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

  11. Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

    International Nuclear Information System (INIS)

    Hölzel, Christina S.; Müller, Christa; Harms, Katrin S.; Mikolajewski, Sabine; Schäfer, Stefanie; Schwaiger, Karin; Bauer, Johann

    2012-01-01

    Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08–5.30 mg cadmium, 1.1–32.0 mg chrome, 22.4–3387.6 mg copper, <2.0–26.7 mg lead, <0.01–0.11 mg mercury, 3.1–97.3 mg nickel and 93.0–8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against β-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against β-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

  12. Development of a miniaturised microarray-based assay for the rapid identification of antimicrobial resistance genes in Gram-negative bacteria

    DEFF Research Database (Denmark)

    Batchelor, Miranda; Hopkins, Katie L; Liebana, Ernesto

    2008-01-01

    We describe the development of a miniaturised microarray for the detection of antimicrobial resistance genes in Gram-negative bacteria. Included on the array are genes encoding resistance to aminoglycosides, trimethoprim, sulphonamides, tetracyclines and beta-lactams, including extended-spectrum ...

  13. Diversity and environmental relations of cryptic, systemic Botrytis infections in symptomless hosts.

    Directory of Open Access Journals (Sweden)

    Michael W. Shaw

    2016-05-01

    Full Text Available Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. B. cinerea and B. pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles.

  14. Potentiation of antibiotic activity of aminoglycosides by natural products from Cordia verbenacea DC.

    Science.gov (United States)

    Matias, Edinardo F F; Alves, Erivania F; Silva, Maria K N; Carvalho, Victoria R A; Medeiros, Cassio R; Santos, Francisco A V; Bitu, Vanessa C N; Souza, Celestina E S; Figueredo, Fernando G; Boligon, Aline A; Athayde, Margareth L; Costa, José G M; Coutinho, Henrique D M

    2016-06-01

    Medicinal plants are often the only therapeutic resource for many communities and ethnic groups. Cordia verbenacea DC., "Erva-baleeira," is one of the species of plants currently used to produce a phytotherapeutic product extracted from its leaves. The present study aimed to establish its chemical profile, antibacterial activity and resistance-modulating potential. The C. verbenacea extracts were prepared from fresh leaves using solvents as methanol and hexane. Ethyl Acetate was used for the preparation of the fraction. Phytochemical screening was carried out using HPLC-DAD for determination and quantification of the secondary metabolites present in the fractions. Antibacterial and resistance-modulation assays were performed to determine minimum inhibitory concentration (MIC) using a microdilution assay. The data were subjected to statistical analysis with two-way ANOVA and Bonferroni posttests. Results of phytochemical prospecting and HPLC analysis of the fractions were in agreement with the literature. The natural products presented moderate antibacterial activity when considering the clinical relevance of a MIC of 256 μg/mL against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, and 512 μg/mL against P. aeruginosa. However, when the fractions were combined with antibiotics we observed a synergic effect, as natural products enhanced the antibacterial effect of aminoglycosides, significantly decreasing the MIC of antibiotics at 12.5%-98.4%. We believe that the data obtained from phytochemical analysis and from antibacterial and resistance modulation assays of C. verbenacea extracts new can open perspectives in the search for new alternatives for the treatment of bacterial infections and stimulate the renewed use of antibiotics with reduced effectiveness due to resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Whole genome sequencing-based characterization of extensively drug resistant (XDR) strains of Mycobacterium tuberculosis from Pakistan

    KAUST Repository

    Hasan, Zahra; Ali, Asho; McNerney, Ruth; Mallard, Kim; Hill-Cawthorne, Grant A.; Coll, Francesc; Nair, Mridul; Pain, Arnab; Clark, Taane G.; Hasan, Rumina

    2015-01-01

    Objectives: The global increase in drug resistance in Mycobacterium tuberculosis (MTB) strains increases the focus on improved molecular diagnostics for MTB. Extensively drug-resistant (XDR) - TB is caused by MTB strains resistant to rifampicin, isoniazid, fluoroquinolone and aminoglycoside antibiotics. Resistance to anti-tuberculous drugs has been associated with single nucleotide polymorphisms (SNPs), in particular MTB genes. However, there is regional variation between MTB lineages and the SNPs associated with resistance. Therefore, there is a need to identify common resistance conferring SNPs so that effective molecular-based diagnostic tests for MTB can be developed. This study investigated used whole genome sequencing (WGS) to characterize 37 XDR MTB isolates from Pakistan and investigated SNPs related to drug resistance. Methods: XDR-TB strains were selected. DNA was extracted from MTB strains, and samples underwent WGS with 76-base-paired end fragment sizes using Illumina paired end HiSeq2000 technology. Raw sequence data were mapped uniquely to H37Rv reference genome. The mappings allowed SNPs and small indels to be called using SAMtools/BCFtools. Results: This study found that in all XDR strains, rifampicin resistance was attributable to SNPs in the rpoB RDR region. Isoniazid resistance-associated mutations were primarily related to katG codon 315 followed by inhA S94A. Fluoroquinolone resistance was attributable to gyrA 91-94 codons in most strains, while one did not have SNPs in either gyrA or gyrB. Aminoglycoside resistance was mostly associated with SNPs in rrs, except in 6 strains. Ethambutol resistant strains had embB codon 306 mutations, but many strains did not have this present. The SNPs were compared with those present in commercial assays such as LiPA Hain MDRTBsl, and the sensitivity of the assays for these strains was evaluated. Conclusions: If common drug resistance associated with SNPs evaluated the concordance between phenotypic and

  16. Whole genome sequencing-based characterization of extensively drug resistant (XDR) strains of Mycobacterium tuberculosis from Pakistan

    KAUST Repository

    Hasan, Zahra

    2015-03-01

    Objectives: The global increase in drug resistance in Mycobacterium tuberculosis (MTB) strains increases the focus on improved molecular diagnostics for MTB. Extensively drug-resistant (XDR) - TB is caused by MTB strains resistant to rifampicin, isoniazid, fluoroquinolone and aminoglycoside antibiotics. Resistance to anti-tuberculous drugs has been associated with single nucleotide polymorphisms (SNPs), in particular MTB genes. However, there is regional variation between MTB lineages and the SNPs associated with resistance. Therefore, there is a need to identify common resistance conferring SNPs so that effective molecular-based diagnostic tests for MTB can be developed. This study investigated used whole genome sequencing (WGS) to characterize 37 XDR MTB isolates from Pakistan and investigated SNPs related to drug resistance. Methods: XDR-TB strains were selected. DNA was extracted from MTB strains, and samples underwent WGS with 76-base-paired end fragment sizes using Illumina paired end HiSeq2000 technology. Raw sequence data were mapped uniquely to H37Rv reference genome. The mappings allowed SNPs and small indels to be called using SAMtools/BCFtools. Results: This study found that in all XDR strains, rifampicin resistance was attributable to SNPs in the rpoB RDR region. Isoniazid resistance-associated mutations were primarily related to katG codon 315 followed by inhA S94A. Fluoroquinolone resistance was attributable to gyrA 91-94 codons in most strains, while one did not have SNPs in either gyrA or gyrB. Aminoglycoside resistance was mostly associated with SNPs in rrs, except in 6 strains. Ethambutol resistant strains had embB codon 306 mutations, but many strains did not have this present. The SNPs were compared with those present in commercial assays such as LiPA Hain MDRTBsl, and the sensitivity of the assays for these strains was evaluated. Conclusions: If common drug resistance associated with SNPs evaluated the concordance between phenotypic and

  17. Correlations between Income inequality and antimicrobial resistance.

    Science.gov (United States)

    Kirby, Andrew; Herbert, Annie

    2013-01-01

    The aim of this study is to investigate if correlations exist between income inequality and antimicrobial resistance. This study's hypothesis is that income inequality at the national level is positively correlated with antimicrobial resistance within developed countries. Income inequality data were obtained from the Standardized World Income Inequality Database. Antimicrobial resistance data were obtained from the European antimicrobial Resistance Surveillance Network and outpatient antimicrobial consumption data, measured by Defined daily Doses per 1000 inhabitants per day, from the European Surveillance of antimicrobial Consumption group. Spearman's correlation coefficient (r) defined strengths of correlations of: > 0.8 as strong, > 0.5 as moderate and > 0.2 as weak. Confidence intervals and p values were defined for all r values. Correlations were calculated for the time period 2003-10, for 15 European countries. Income inequality and antimicrobial resistance correlations which were moderate or strong, with 95% confidence intervals > 0, included the following. Enterococcus faecalis resistance to aminopenicillins, vancomycin and high level gentamicin was moderately associated with income inequality (r= ≥0.54 for all three antimicrobials). Escherichia coli resistance to aminoglycosides, aminopenicillins, third generation cephalosporins and fluoroquinolones was moderately-strongly associated with income inequality (r= ≥0.7 for all four antimicrobials). Klebsiella pneumoniae resistance to third generation cephalosporins, aminoglycosides and fluoroquinolones was moderately associated with income inequality (r= ≥0.5 for all three antimicrobials). Staphylococcus aureus methicillin resistance and income inequality were strongly associated (r=0.87). As income inequality increases in European countries so do the rates of antimicrobial resistance for bacteria including E. faecalis, E. coli, K. pneumoniae and S. aureus. Further studies are needed to confirm these

  18. Whole genome sequencing-based characterization of extensively drug resistant (XDR strains of Mycobacterium tuberculosis from Pakistan

    Directory of Open Access Journals (Sweden)

    Zahra Hasan

    2015-01-01

    Conclusions: If common drug resistance associated with SNPs evaluated the concordance between phenotypic and genotypic testing, the results would be rifampicin (100%, isoniazid (89%, fluoroquinolones (95%, aminoglycoside (81% and ethambutol (61%. This work highlights the importance of expanded targets for drug resistance detection in MTB isolates.

  19. Risk Factors for Emergence of Resistance to Broad-Spectrum Cephalosporins among Enterobacter spp.

    Science.gov (United States)

    Kaye, Keith S.; Cosgrove, Sara; Harris, Anthony; Eliopoulos, George M.; Carmeli, Yehuda

    2001-01-01

    Among 477 patients with susceptible Enterobacter spp., 49 subsequently harbored third-generation cephalosporin-resistant Enterobacter spp. Broad-spectrum cephalosporins were independent risk factors for resistance (relative risk [OR] = 2.3, P = 0.01); quinolone therapy was protective (OR = 0.4, P = 0.03). There were trends toward decreased risk for resistance among patients receiving broad-spectrum cephalosporins and either aminoglycosides or imipenem. Of the patients receiving broad-spectrum cephalosporins, 19% developed resistance. PMID:11502540

  20. Mitochondrial 12S rRNA A827G mutation is involved in the genetic susceptibility to aminoglycoside ototoxicity

    International Nuclear Information System (INIS)

    Xing Guangqian; Chen Zhibin; Wei Qinjun; Tian Huiqin; Li Xiaolu; Zhou Aidong; Bu Xingkuan; Cao Xin

    2006-01-01

    We have analyzed the clinical and molecular characterization of a Chinese family with aminoglycoside-induced and non-syndromic hearing impairment. Clinical evaluations revealed that only those family members who had a history of exposure to aminoglycoside antibiotics subsequently developed hearing loss, suggesting mitochondrial genome involvement. Sequence analysis of the mitochondrial 12S rRNA and tRNA Ser(UCN) genes led to the identification of a homoplasmic A827G mutation in all maternal relatives, a mutation that was identified previously in a few sporadic patients and in another Chinese family with non-syndromic deafness. The pathogenicity of the A827G mutation is strongly supported by the occurrence of the same mutation in two independent families and several genetically unrelated subjects. The A827G mutation is located at the A-site of the mitochondrial 12S rRNA gene which is highly conserved in mammals. It is possible that the alteration of the tertiary or quaternary structure of this rRNA by the A827G mutation may lead to mitochondrial dysfunction, thereby playing a role in the pathogenesis of hearing loss and aminoglycoside hypersensitivity. However, incomplete penetrance of hearing impairment indicates that the A827G mutation itself is not sufficient to produce clinical phenotype but requires the involvement of modifier factors for the phenotypic expression. Indeed, aminoglycosides may contribute to the phenotypic manifestation of the A827G mutation in this family. In contrast with the congenital or early-onset hearing impairment in another Chinese family carrying the A827G mutation, three patients in this pedigree developed hearing loss only after use of aminoglycosides. This discrepancy likely reflects the difference of genetic backgrounds, either mitochondrial haplotypes or nuclear modifier genes, between two families

  1. The Sensitivity to Aminoglycosides and Heavy Metals of Isolates of ...

    African Journals Online (AJOL)

    Eighty-two clinical isolates of Pseudomonas aeruginosa strains were tested for their sensitivity to aminoglycosides by an agar diffusion method and to heavy metals by a dilution technique on tri –buffered mineral salt agar containing 10 – 100mg/L CdCl2.H20, CoCl2.6H20, ZnCl2, AgNO3 and HgCl2. All the strains tested ...

  2. Early transcriptional response to aminoglycoside antibiotic suggests alternate pathways leading to apoptosis of sensory hair cells in the mouse inner ear

    Directory of Open Access Journals (Sweden)

    Neil eSegil

    2015-05-01

    Full Text Available Aminoglycoside antibiotics are the drug of choice for treating many bacterial infections, but their administration results in hearing loss in nearly one fourth of the patients who receive them. Several biochemical pathways have been implicated in aminoglycoside antibiotic ototoxicity; however, little is known about how hair cells respond to aminoglycoside antibiotics at the transcriptome level. Here we have investigated the genome-wide response to the aminoglycoside antibiotic gentamicin. Using organotypic cultures of the perinatal organ of Corti, we performed RNA sequencing using cDNA libraries obtained from FACS-purified hair cells. Within 3 hours of gentamicin treatment, the messenger RNA level of more than three thousand genes in hair cells changed significantly. Bioinformatic analysis of these changes highlighted several known signal transduction pathways, including the JNK pathway and the NF-κB pathway, in addition to genes involved in the stress response, apoptosis, cell cycle control, and DNA damage repair. In contrast, only 698 genes, mainly involved in cell cycle and metabolite biosynthetic processes, were significantly affected in the non-hair cell population. The gene expression profiles of hair cells in response to gentamicin share a considerable similarity with those previously observed in gentamicin-induced nephrotoxicity. Our findings suggest that previously observed early responses to gentamicin in hair cells in specific signaling pathways are reflected in changes in gene expression. Additionally, the observed changes in gene expression of cell cycle regulatory genes indicate a disruption of the postmitotic state, which may suggest an alternative pathway regulating gentamicin-induced hair cell death. This work provides a more comprehensive view of aminoglycoside antibiotic ototoxicity, and thus contribute to identifying potential pathways or therapeutic targets to alleviate this important side effect of aminoglycoside

  3. Metal and antibiotic resistance of bacteria isolated from the Baltic Sea.

    Science.gov (United States)

    Moskot, Marta; Kotlarska, Ewa; Jakóbkiewicz-Banecka, Joanna; Gabig-Cimińska, Magdalena; Fari, Karolina; Wegrzyn, Grzegorz; Wróbel, Borys

    2012-09-01

    The resistance of 49 strains of bacteria isolated from surface Baltic Sea waters to 11 antibiotics was analyzed and the resistance of selected strains to three metal ions (Ni2+, Mn2+, Zn2+) was tested. Most isolates belonged to Gammaproteobacteria (78%), while Alphaproteobacteria (8%), Actinobacteria (10%), and Bacteroidetes (4%) were less abundant. Even though previous reports suggested relationships between resistance and the presence of plasmids or the ability to produce pigments, no compelling evidence for such relationships was obtained for the strains isolated in this work. In particular, strains resistant to multiple antibiotics did not carry plasmids more frequently than sensitive strains. A relation between resistance and the four aminoglycosides tested (gentamycin, kanamycin, neomycin, and streptomycin), but not to spectinomycin, was demonstrated. This observation is of interest given that spectinomycin is not always classified as an aminoglycoside because it lacks a traditional sugar moiety. Statistical analysis indicated relationships between resistance to some antibiotics (ampicillin and erythromycin, chloramphenicol and erythromycin, chloramphenicol and tetracycline, erythromycin and tetracycline), suggesting the linkage of resistance genes for antibiotics belonging to different classes. The effects of NiSO4, ZnCl2 and MnCl2 on various media suggested that the composition of Marine Broth might result in low concentrations of Mn2+ due to chemical interactions that potentially lead to precipitation.

  4. Single biosensor immunoassay for the detection of five aminoglycosides in reconstituted skimmed milk

    NARCIS (Netherlands)

    Haasnoot, W.; Cazemier, G.; Koets, M.; Amerongen, van A.

    2003-01-01

    The application of an optical biosensor (Biacore 3000), with four flow channels (Fcs), in combination with a mixture of four specific antibodies resulted in a competitive inhibition biosensor immunoassay (BIA) for the simultaneous detection of the five relevant aminoglycosides in reconstituted

  5. Effect of basic amino acids and aminoglycosides on 3H-gentamicin uptake in cortical slices of rat and human kindney

    International Nuclear Information System (INIS)

    Bennett, W.M.; Plamp, C.E.; Elliott, W.C.; Parker, R.A.; Porter, G.A.

    1982-01-01

    The uptake of 3 H-gentamicin was assessed in renal cortical slices of Fischer 344 male rats and four human cadaver kidneys not utilized for renal transplantation. In both species the uptake was maximal at 90 min and maintained a steady state therafter. The characteristics of the energy-dependent component of 3 H-gentamicin uptake were not altered by various basic amino acids, but competitive inhibition was induced by other aminoglycosides in a dose-dependent fashion. Thus aminoglycosides appear to share a transport process that is distinct from those of organic bases or other cationic substances. In addition, under the experimental conditions employed, the basolateral membranes of the tubular cell is capable of energy-dependent uptake of gentamicin. The role of this route of cellular uptake of aminoglycoside in clinical nephrotoxicity is speculative

  6. Regulation of the Two-Component Regulator CpxR on Aminoglycosides and β-lactams Resistance in Salmonella enterica Serovar Typhimurium

    Directory of Open Access Journals (Sweden)

    Hui eHuang

    2016-04-01

    RNA expression levels of the efflux pump acrD and mdtA genes, as compared to strain JS△cpxR. Our results indicate that the two-component regulator CpxR contributes to resistance of S. enterica serovar Typhimurium to aminoglycosides and β-lactams by influencing the expression level of the MDR-related genes.

  7. Role of Bacterioferritin & Ferritin in M. tuberculosis Pathogenesis and Drug Resistance: A Future Perspective by Interactomic Approach

    Directory of Open Access Journals (Sweden)

    Divakar Sharma

    2017-06-01

    Full Text Available Tuberculosis is caused by Mycobacterium tuberculosis, one of the most successful and deadliest human pathogen. Aminoglycosides resistance leads to emergence of extremely drug resistant strains of M. tuberculosis. Iron is crucial for the biological functions of the cells. Iron assimilation, storage and their utilization is not only involved in pathogenesis but also in emergence of drug resistance strains. We previously reported that iron storing proteins (bacterioferritin and ferritin were found to be overexpressed in aminoglycosides resistant isolates. In this study we performed the STRING analysis of bacterioferritin & ferritin proteins and predicted their interactive partners [ferrochelatase (hemH, Rv1877 (hypothetical protein/probable conserved integral membrane protein, uroporphyrinogen decarboxylase (hemE trigger factor (tig, transcriptional regulatory protein (MT3948, hypothetical protein (MT1928, glnA3 (glutamine synthetase, molecular chaperone GroEL (groEL1 & hsp65, and hypothetical protein (MT3947]. We suggested that interactive partners of bacterioferritin and ferritin are directly or indirectly involved in M. tuberculosis growth, homeostasis, iron assimilation, virulence, resistance, and stresses.

  8. Volatile compounds in cryptic species of the Aneura pinguis complex and Aneura maxima (Marchantiophyta, Metzgeriidae).

    Science.gov (United States)

    Wawrzyniak, Rafał; Wasiak, Wiesław; Bączkiewicz, Alina; Buczkowska, Katarzyna

    2014-09-01

    Aneura pinguis is one of the liverwort species complexes that consist of several cryptic species. Ten samples collected from different regions in Poland are in the focus of our research. Eight of the A. pinguis complex belonging to four cryptic species (A, B, C, E) and two samples of closely related species Aneura maxima were tested for the composition of volatile compounds. The HS-SPME technique coupled to GC/FID and GC/MS analysis has been applied. The fiber coated with DVB/CAR/PDMS has been used. The results of the present study, revealed the qualitative and quantitative differences in the composition of the volatile compounds between the studied species. Mainly they are from the group of sesquiterpenoids, oxygenated sesquiterpenoids and aliphatic hydrocarbons. The statistical methods (CA and PCA) showed that detected volatile compounds allow to distinguish cryptic species of A. pinguis. All examined cryptic species of the A. pinguis complex differ from A. maxima. Species A and E of A. pinguis, in CA and PCA, form separate clusters remote from two remaining cryptic species of A. pinguis (B and C) and A. maxima. Relationship between the cryptic species appeared from the chemical studies are in accordance with that revealed on the basis of DNA sequences. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Risk factors and outcomes of carbapenem-resistant Klebsiella pneumoniae infections

    Directory of Open Access Journals (Sweden)

    Eleonora Pistella

    2016-12-01

    Full Text Available In the nosocomial setting, antimicrobial-resistant Enterobacteriaceae are a growing challenge, and alarming trends in resistance are currently reported all over the world. Isolates of Enterobacteriaceae producing ampC β-lactamases and extended spectrum β-lactamases are endemic in many hospitals, and are frequently resistant also to other classes of antibiotics, such as fluoroquinolones and aminoglycosides. The risk of infections due to multi-drug resistant strains should be considered also for outpatients who have had recent contact with the health system. Both nosocomial and health-care associated infections should be treated with a combination of antibiotics active against multi-drug resistant Gram negative and methicillin-resistant Staphylococcus aureus. In the absence of effective antimicrobial stewardship programs, this aggressive therapeutic approach might lead to abuse of broad-spectrum antibiotics, with consequent increase in resistances. To contain the possible antibiotic overuse, several decisional strategies, often based on risk-score systems supporting the clinical decisions, have been proposed. In this context of high antibiotic selection pressure, carbapenem-resistant pathogens recently began to spread in many hospitals. Carbapenem-resistant Klebsiella pneumoniae, as well as carbapenem-resistant Acinetobacter baumannii and P. aeruginosa, represent the new major challenges to patient safety. Against these organisms the initial empiric treatment is generally ineffective. The poor clinical outcome associated with carbapenem- resistant K. pneumoniae infections is probably due to the delete in the beginning of an appropriate antibiotic treatment, rather than to the increased virulence of pathogens. Only few therapeutic options are available, including colistin, tigecycline, aminoglycosides and carbapenems in selected cases. Several combinations of these antibiotics have been used, but no ideal regimen has been currently established.

  10. Wild-type MIC distributions for aminoglycoside and cyclic polypeptide antibiotics used for treatment of Mycobacterium tuberculosis infections.

    Science.gov (United States)

    Juréen, P; Angeby, K; Sturegård, E; Chryssanthou, E; Giske, C G; Werngren, J; Nordvall, M; Johansson, A; Kahlmeter, G; Hoffner, S; Schön, T

    2010-05-01

    The aminoglycosides and cyclic polypeptides are essential drugs in the treatment of multidrug-resistant tuberculosis, underscoring the need for accurate and reproducible drug susceptibility testing (DST). The epidemiological cutoff value (ECOFF) separating wild-type susceptible strains from non-wild-type strains is an important but rarely used tool for indicating susceptibility breakpoints against Mycobacterium tuberculosis. In this study, we established wild-type MIC distributions on Middlebrook 7H10 medium for amikacin, kanamycin, streptomycin, capreomycin, and viomycin using 90 consecutive clinical isolates and 21 resistant strains. Overall, the MIC variation between and within runs did not exceed +/-1 MIC dilution step, and validation of MIC values in Bactec 960 MGIT demonstrated good agreement. Tentative ECOFFs defining the wild type were established for all investigated drugs, including amikacin and viomycin, which currently lack susceptibility breakpoints for 7H10. Five out of seven amikacin- and kanamycin-resistant isolates were classified as susceptible to capreomycin according to the current critical concentration (10 mg/liter) but were non-wild type according to the ECOFF (4 mg/liter), suggesting that the critical concentration may be too high. All amikacin- and kanamycin-resistant isolates were clearly below the ECOFF for viomycin, and two of them were below the ECOFF for streptomycin, indicating that these two drugs may be considered for treatment of amikacin-resistant strains. Pharmacodynamic indices (peak serum concentration [Cmax]/MIC) were more favorable for amikacin and viomycin compared to kanamycin and capreomycin. In conclusion, our data emphasize the importance of establishing wild-type MIC distributions for improving the quality of drug susceptibility testing against Mycobacterium tuberculosis.

  11. Chaperonins fight aminoglycoside-induced protein misfolding and promote short-term tolerance in Escherichia coli

    DEFF Research Database (Denmark)

    Goltermann, Lise; Good, Liam; Bentin, Thomas

    2013-01-01

    For almost half of a century, we have known that aminoglycoside antibiotics corrupt ribosomes, causing translational misreading, yet it remains unclear whether or not misreading triggers protein misfolding, and possible effects of chaperone action on drug susceptibilities are poorly understood...

  12. Influence of very short patch mismatch repair on SOS inducing lesions after aminoglycoside treatment in Escherichia coli.

    Science.gov (United States)

    Baharoglu, Zeynep; Mazel, Didier

    2014-01-01

    Low concentrations of aminoglycosides induce the SOS response in Vibrio cholerae but not in Escherichia coli. In order to determine whether a specific factor present in E. coli prevents this induction, we developed a genetic screen where only SOS inducing mutants are viable. We identified the vsr gene coding for the Vsr protein of the very short patch mismatch repair (VSPR) pathway. The effect of mismatch repair (MMR) mutants was also studied. We propose that lesions formed upon aminoglycoside treatment are preferentially repaired by VSPR without SOS induction in E. coli and by MMR when VSPR is impaired. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  13. The association between measurements of antimicrobial use and resistance in the faeces microbiota of finisher batches.

    Science.gov (United States)

    Andersen, V D; DE Knegt, L V; Munk, P; Jensen, M S; Agersø, Y; Aarestrup, F M; Vigre, H

    2017-10-01

    The objectives were to present three approaches for calculating antimicrobial (AM) use in pigs that take into account the rearing period and rearing site, and to study the association between these measurements and phenotypical resistance and abundance of resistance genes in faeces samples from 10 finisher batches. The AM use was calculated relative to the rearing period of the batches as (i) 'Finisher Unit Exposure' at unit level, (ii) 'Lifetime Exposure' at batch level and (iii) 'Herd Exposure' at herd level. A significant effect on the occurrence of tetracycline resistance measured by cultivation was identified for Lifetime Exposure for the AM class: tetracycline. Furthermore, for Lifetime Exposure for the AM classes: macrolide, broad-spectrum penicillin, sulfonamide and tetracycline use as well as Herd Unit Exposure for the AM classes: aminoglycoside, lincosamide and tetracycline use, a significant effect was observed on the occurrence of genes coding for the AM resistance classes: aminoglycoside, lincosamide, macrolide, β-lactam, sulfonamide and tetracycline. No effect was observed for Finisher Unit Exposure. Overall, the study shows that Lifetime Exposure is an efficient measurement of AM use in finisher batches, and has a significant effect on the occurrence of resistance, measured either by cultivation or metagenomics.

  14. Risk of Gonadoblastoma Development in Patients with Turner Syndrome with Cryptic Y Chromosome Material.

    Science.gov (United States)

    Kwon, Ahreum; Hyun, Sei Eun; Jung, Mo Kyung; Chae, Hyun Wook; Lee, Woo Jung; Kim, Tae Hyuk; Kim, Duk Hee; Kim, Ho-Seong

    2017-06-01

    Current guidelines recommend that testing for Y chromosome material should be performed only in patients with Turner syndrome harboring a marker chromosome and exhibiting virilization in order to detect individuals who are at high risk of gonadoblastoma. However, cryptic Y chromosome material is suggested to be a risk factor for gonadoblastoma in patients with Turner syndrome. Here, we aimed to estimate the frequency of cryptic Y chromosome material in patients with Turner syndrome and determine whether Y chromosome material increased the risk for development of gonadoblastoma. A total of 124 patients who were diagnosed with Turner syndrome by conventional cytogenetic techniques underwent additional molecular analysis to detect cryptic Y chromosome material. In addition, patients with Turner syndrome harboring Y chromosome cell lines had their ovaries removed prophylactically. Finally, we assessed the occurrence of gonadoblastoma in patients with Turner syndrome. Molecular analysis demonstrated that 10 patients had Y chromosome material among 118 patients without overt Y chromosome (8.5%). Six patients with overt Y chromosome and four patients with cryptic Y chromosome material underwent oophorectomy. Histopathological analysis revealed that the occurrence of gonadoblastoma in the total group was 2.4%, and gonadoblastoma occurred in one of six patients with an overt Y chromosome (16.7%) and 2 of 10 patients with cryptic Y chromosome material (20.0%). The risk of developing gonadoblastoma in patients with cryptic Y chromosome material was similar to that in patients with overt Y chromosome. Therefore, molecular screening for Y chromosome material should be recommended for all patients with Turner syndrome to detect individuals at a high risk of gonadoblastoma and to facilitate proper management of the disease.

  15. Draft Genome Sequence of a Multidrug-Resistant Klebsiella quasipneumoniae subsp. similipneumoniae Isolate from a Clinical Source

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Egon A.; Morris, Andrew R.; Krapp, Fiorella; Henry, Christopher S.; Tyo, Keith E.; Lathem, Wyndham W.; Hauser, Alan R.

    2016-05-26

    We report here the draft genome sequence of a multidrug-resistant clinical isolate ofKlebsiella quasipneumoniaesubsp.similipneumoniae, KP_Z4175. This strain, isolated as part of a hospital infection-control screening program, is resistant to multiple β-lactam antibiotics, aminoglycosides, and trimethoprim-sulfamethoxazole.

  16. The effect of the circadian rhythm on the clearance of aminoglycosides in ICU patients

    NARCIS (Netherlands)

    Van Maarseveen, E.; Proost, J.; Neef, C.; Touw, D.

    Aims: Critically ill patients, admitted to an intensive care unit, are at high risk of acquiring a nosocomial infection. Aminoglycosides (AMGs) are frequently used as first line therapy in severe hospital-acquired pneumonia or sepsis. It has been shown that once daily dosing (ODD) can reduce toxic

  17. DNA barcoding applied to ex situ tropical amphibian conservation programme reveals cryptic diversity in captive populations.

    Science.gov (United States)

    Crawford, Andrew J; Cruz, Catalina; Griffith, Edgardo; Ross, Heidi; Ibáñez, Roberto; Lips, Karen R; Driskell, Amy C; Bermingham, Eldredge; Crump, Paul

    2013-11-01

    Amphibians constitute a diverse yet still incompletely characterized clade of vertebrates, in which new species are still being discovered and described at a high rate. Amphibians are also increasingly endangered, due in part to disease-driven threats of extinctions. As an emergency response, conservationists have begun ex situ assurance colonies for priority species. The abundance of cryptic amphibian diversity, however, may cause problems for ex situ conservation. In this study we used a DNA barcoding approach to survey mitochondrial DNA (mtDNA) variation in captive populations of 10 species of Neotropical amphibians maintained in an ex situ assurance programme at El Valle Amphibian Conservation Center (EVACC) in the Republic of Panama. We combined these mtDNA sequences with genetic data from presumably conspecific wild populations sampled from across Panama, and applied genetic distance-based and character-based analyses to identify cryptic lineages. We found that three of ten species harboured substantial cryptic genetic diversity within EVACC, and an additional three species harboured cryptic diversity among wild populations, but not in captivity. Ex situ conservation efforts focused on amphibians are therefore vulnerable to an incomplete taxonomy leading to misidentification among cryptic species. DNA barcoding may therefore provide a simple, standardized protocol to identify cryptic diversity readily applicable to any amphibian community. © 2012 John Wiley & Sons Ltd.

  18. Wild-Type MIC Distributions for Aminoglycoside and Cyclic Polypeptide Antibiotics Used for Treatment of Mycobacterium tuberculosis Infections▿

    Science.gov (United States)

    Juréen, P.; Ängeby, K.; Sturegård, E.; Chryssanthou, E.; Giske, C. G.; Werngren, J.; Nordvall, M.; Johansson, A.; Kahlmeter, G.; Hoffner, S.; Schön, T.

    2010-01-01

    The aminoglycosides and cyclic polypeptides are essential drugs in the treatment of multidrug-resistant tuberculosis, underscoring the need for accurate and reproducible drug susceptibility testing (DST). The epidemiological cutoff value (ECOFF) separating wild-type susceptible strains from non-wild-type strains is an important but rarely used tool for indicating susceptibility breakpoints against Mycobacterium tuberculosis. In this study, we established wild-type MIC distributions on Middlebrook 7H10 medium for amikacin, kanamycin, streptomycin, capreomycin, and viomycin using 90 consecutive clinical isolates and 21 resistant strains. Overall, the MIC variation between and within runs did not exceed ±1 MIC dilution step, and validation of MIC values in Bactec 960 MGIT demonstrated good agreement. Tentative ECOFFs defining the wild type were established for all investigated drugs, including amikacin and viomycin, which currently lack susceptibility breakpoints for 7H10. Five out of seven amikacin- and kanamycin-resistant isolates were classified as susceptible to capreomycin according to the current critical concentration (10 mg/liter) but were non-wild type according to the ECOFF (4 mg/liter), suggesting that the critical concentration may be too high. All amikacin- and kanamycin-resistant isolates were clearly below the ECOFF for viomycin, and two of them were below the ECOFF for streptomycin, indicating that these two drugs may be considered for treatment of amikacin-resistant strains. Pharmacodynamic indices (peak serum concentration [Cmax]/MIC) were more favorable for amikacin and viomycin compared to kanamycin and capreomycin. In conclusion, our data emphasize the importance of establishing wild-type MIC distributions for improving the quality of drug susceptibility testing against Mycobacterium tuberculosis. PMID:20237102

  19. Targeting a Hidden Enemy: Pyriproxyfen Autodissemination Strategy for the Control of the Container Mosquito Aedes albopictus in Cryptic Habitats.

    Directory of Open Access Journals (Sweden)

    Kshitij Chandel

    2016-12-01

    Full Text Available The Asian tiger mosquito, Aedes albopictus, is a vector of dengue, Chikungunya, and Zika viruses. This mosquito inhabits a wide range of artificial water-holding containers in urban and suburban areas making it difficult to control. We tested the hypothesis that female-driven autodissemination of an insect growth regulator could penetrate cryptic oviposition habitats difficult to treat with conventional insecticidal sprays.Oviposition preferences of Ae. albopictus females for open and cryptic cups were tested in semi-field experiments. Two conventional larvicidal sprayers were tested to determine droplet penetration and larvicidal efficacy in open and cryptic habitats using Bacillus thuringiensis var. israelensis (Bti in the field. Finally, the efficacy of pyriproxyfen autodissemination stations was assessed in cryptic and open cups in residential areas during 2013 and 2014.Gravid females strongly preferred cryptic (53.1±12.9 eggs/cup over open (10.3±4.3 eggs/cup cups for oviposition. Cryptic cups showed limited droplet penetration and produced 0.1-0.3% larval mortality with a conventional backpack and low-volume sprays of Bti. The autodissemination stations effectively contaminated these cryptic cups (59.3-84.6% and produced 29.7-40.8% pupal mortality during 2013-2014. Significant pupal mortality was also observed in open cups.The autodissemination station effectively exploits the oviposition behavior of wild gravid females to deliver pyriproxyfen to targeted oviposition habitats. Although the pupal mortality in cryptic cups was relatively lower than expected for the effective vector control. Autodissemination approach may be a suitable supporting tool to manage Ae. albopictus immatures in the cryptic habitats those are less accessible to conventional larvicidal sprays.

  20. Biochemical and Structural Analysis of an Eis Family Aminoglycoside Acetyltransferase from Bacillus anthracis

    Energy Technology Data Exchange (ETDEWEB)

    Green, Keith D.; Biswas, Tapan; Chang, Changsoo; Wu, Ruiying; Chen, Wenjing; Janes, Brian K.; Chalupska, Dominika; Gornicki, Piotr; Hanna, Philip C.; Tsodikov, Oleg V.; Joachimiak, Andrzej; Garneau-Tsodikova, Sylvie

    2015-05-26

    Proteins from the enhanced intracellular survival (Eis) family are versatile acetyltransferases that acetylate amines at multiple positions of several aminoglycosides (AGs). Their upregulation confers drug resistance. Homologues of Eis are present in diverse bacteria, including many pathogens. Eis from Mycobacterium tuberculosis (Eis_Mtb) has been well characterized. In this study, we explored the AG specificity and catalytic efficiency of the Eis family protein from Bacillus anthracis (Eis_Ban). Kinetic analysis of specificity and catalytic efficiency of acetylation of six AGs indicates that Eis_Ban displays significant differences from Eis_Mtb in both substrate binding and catalytic efficiency. The number of acetylated amines was also different for several AGs, indicating a distinct regiospecificity of Eis_Ban. Furthermore, most recently identified inhibitors of Eis_Mtb did not inhibit Eis_Ban, underscoring the differences between these two enzymes. To explain these differences, we determined an Eis_Ban crystal structure. The comparison of the crystal structures of Eis_Ban and Eis_Mtb demonstrates that critical residues lining their respective substrate binding pockets differ substantially, explaining their distinct specificities. Our results suggest that acetyltransferases of the Eis family evolved divergently to garner distinct specificities while conserving catalytic efficiency, possibly to counter distinct chemical challenges. The unique specificity features of these enzymes can be utilized as tools for developing AGs with novel modifications and help guide specific AG treatments to avoid Eis-mediated resistance.

  1. Cryptic species as a window into the paradigm shift of the species concept.

    Science.gov (United States)

    Fišer, Cene; Robinson, Christopher T; Malard, Florian

    2018-02-01

    The species concept is the cornerstone of biodiversity science, and any paradigm shift in the delimitation of species affects many research fields. Many biologists now are embracing a new "species" paradigm as separately evolving populations using different delimitation criteria. Individual criteria can emerge during different periods of speciation; some may never evolve. As such, a paradigm shift in the species concept relates to this inherent heterogeneity in the speciation process and species category-which is fundamentally overlooked in biodiversity research. Cryptic species fall within this paradigm shift: they are continuously being reported from diverse animal phyla but are poorly considered in current tests of ecological and evolutionary theory. The aim of this review is to integrate cryptic species in biodiversity science. In the first section, we address that the absence of morphological diversification is an evolutionary phenomenon, a "process" counterpart to the long-studied mechanisms of morphological diversification. In the next section regarding taxonomy, we show that molecular delimitation of cryptic species is heavily biased towards distance-based methods. We also stress the importance of formally naming of cryptic species for better integration into research fields that use species as units of analysis. Finally, we show that incorporating cryptic species leads to novel insights regarding biodiversity patterns and processes, including large-scale biodiversity assessments, geographic variation in species distribution and species coexistence. It is time for incorporating multicriteria species approaches aiming to understand speciation across space and taxa, thus allowing integration into biodiversity conservation while accommodating for species uncertainty. © 2018 John Wiley & Sons Ltd.

  2. Therapeutic drug monitoring by radioimmunoassay: Determination of aminoglycoside antibiotics and vancomycin in plasma

    International Nuclear Information System (INIS)

    Glaubitt, D.; Drechsler, H.J.; Knoch, K.; Siafarikas, K.

    1984-01-01

    Radioimmunoassay of aminoglycoside antibiotics (gentamicin, tobramycin, netilmicin) or vancomycin in plasma may considerably aid to assess their appropriate dosage and, if necessary, to rapidly adjust it to the assumed requirement. Thus the dosage of the antibiotic is kept large enough as to lead to the desired therapeutic result but not as high as to cause side effects. (orig.)

  3. Features of cryptic promoters and their varied reliance on bromodomain-containing factors.

    Directory of Open Access Journals (Sweden)

    Samantha G Pattenden

    Full Text Available The Set2-Rpd3S pathway is important for the control of transcription memory. Mutation of components of this pathway results in cryptic transcription initiation within the coding region of approximately 30% of yeast genes. Specifically, deletion of the Set2 histone methyltransferase or Rco1, a component of the Rpd3S histone deacetylase complex leads to hyperacetylation of certain open reading frames (ORFs. We used this mutant as a system to study the role of histone modifications and co-activator recruitment in preinitiation complex (PIC formation. Specifically, we looked at the dependence of promoters on the bromodomain-containing RSC complex and the Bdf1 protein. We found that the dependence of cryptic promoters for these proteins varied. Overall, our data indicate that cryptic promoters are independently regulated, and their activation is dependent on factors that govern gene activation at canonical promoters.

  4. Towards a genetic architecture of cryptic genetic variation

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 84; Issue 3. Towards a genetic architecture of cryptic genetic variation and genetic assimilation: the contribution of K. G. Bateman. Ian Dworkin. Commentary on J. Genet. Classic Volume 84 Issue 3 December 2005 pp 223-226 ...

  5. Surveillance for Travel and Domestically Acquired Multidrug-Resistant Human Shigella Infections-Pennsylvania, 2006-2014.

    Science.gov (United States)

    Li, Yu Lung; Tewari, Deepanker; Yealy, Courtney C; Fardig, David; M'ikanatha, Nkuchia M

    2016-01-01

    Shigellosis is a leading cause of enteric infections in the United States. We compared antimicrobial resistance in Shigella infections related to overseas travel (travel-associated) and in those acquired domestically by analyzing antimicrobial resistance patterns, geographic distributions, and pulsed-field gel electrophoresis (PFGE) patterns. We tested samples (n = 204) from a collection of isolates recovered from patients in Pennsylvania between 2006 and 2014. Isolates were grouped into travel- and non-travel-associated categories. Eighty-one (79.4%) of the Shigella isolates acquired during international travel were resistant to multiple antibiotics compared to 53 (52.1%) of the infections transmitted in domestic settings. A majority (79.4%) of isolates associated with international travel demonstrated resistance to aminoglycosides and tetracyclines, whereas 47 (46.1%) of the infections acquired domestically were resistant to tetracycline. Almost all isolates (92.2%) transmitted in domestic settings were resistant to aminoglycosides, and 5 isolates from adult male patients were resistant to azithromycin, a drug often used for empiric treatment of severe shigellosis. Twenty (19.6%) isolates associated with illnesses acquired during overseas travel in 4 countries were resistant to quinolones. One S. sonnei PFGE pattern was traced to a multidrug-resistant isolate acquired overseas that had caused a multistate outbreak of shigellosis, suggesting global dissemination of a drug-resistant species. Resistance to certain drugs-for example, tetracycline-increased in both overseas- and domestic-acquired infections during the study period. The prevalence of resistance to macrolides (azithromycin) and third-generation cephalosporins (ceftriaxone) was less than 1%; however, efforts to better monitor changes in drug resistance over time combined with increased antimicrobial stewardship are essential at the local, national, and global levels.

  6. Association between the Presence of Aminoglycoside-Modifying Enzymes and In Vitro Activity of Gentamicin, Tobramycin, Amikacin, and Plazomicin against Klebsiella pneumoniae Carbapenemase- and Extended-Spectrum-β-Lactamase-Producing Enterobacter Species.

    Science.gov (United States)

    Haidar, Ghady; Alkroud, Ammar; Cheng, Shaoji; Churilla, Travis M; Churilla, Bryce M; Shields, Ryan K; Doi, Yohei; Clancy, Cornelius J; Nguyen, M Hong

    2016-09-01

    We compared the in vitro activities of gentamicin (GEN), tobramycin (TOB), amikacin (AMK), and plazomicin (PLZ) against 13 Enterobacter isolates possessing both Klebsiella pneumoniae carbapenemase and extended-spectrum β-lactamase (KPC+/ESBL+) with activity against 8 KPC+/ESBL-, 6 KPC-/ESBL+, and 38 KPC-/ESBL- isolates. The rates of resistance to GEN and TOB were higher for KPC+/ESBL+ (100% for both) than for KPC+/ESBL- (25% and 38%, respectively), KPC-/ESBL+ (50% and 17%, respectively), and KPC-/ESBL- (0% and 3%, respectively) isolates. KPC+/ESBL+ isolates were more likely than others to possess an aminoglycoside-modifying enzyme (AME) (100% versus 38%, 67%, and 5%; P = 0.007, 0.06, and 1 AME than with ≤1 AME. The presence of at least 2/3 of KPC, SHV, and TEM predicted the presence of AMEs. PLZ MICs against all isolates were ≤4 μg/ml, regardless of KPC/ESBL pattern or the presence of AMEs. In conclusion, GEN and TOB are limited as treatment options against KPC+ and ESBL+ Enterobacter PLZ may represent a valuable addition to the antimicrobial armamentarium. A full understanding of AMEs and other aminoglycoside resistance mechanisms will allow clinicians to incorporate PLZ rationally into treatment regimens. The development of molecular assays that accurately and rapidly predict antimicrobial responses among KPC- and ESBL-producing Enterobacter spp. should be a top research priority. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  7. Members of Bemisia tabaci (Hemiptera: Aleyrodidae) Cryptic Species and the Status of Two Invasive Alien Species in the Yunnan Province (China)

    Science.gov (United States)

    Hu, Jian; Jiang, Zhi-Lin; Nardi, Francesco; Liu, Yuan-Yuan; Luo, Xiao-Rong; Li, Hong-Xiang; Zhang, Zhong-Kai

    2014-01-01

    Abstract Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex that includes some of the most significant pests of agriculture and horticulture worldwide. To understand the diversity and distribution of B. tabaci cryptic species in Yunnan, a famous biodiversity hotspot in China, a large-scale sampling was conducted from year 2010 to 2013 in 10 prefectures. Mitochondrial cytochrome oxidase I gene sequences were used to identify different cryptic species. Phylogenetic analyses were performed using Bayesian methods to assess the position of a new B. tabaci cryptic species in the context of the B. tabaci diversity in Asia. The survey indicates at least eight B. tabaci cryptic species are present in Yunnan, two invasive (MEAM1 and MED) and six indigenous (China 2, China3, China 4, Asia I, Asia II 1, and Asia II 6), MEAM1, MED, and Asia I being the three predominant cryptic species in Yunnan. Compared with MEAM1, MED has a wider distribution. Based on molecular data, a new cryptic species, here named China 4, was identified that appears to be related to China 1, China 2, and China 3. Future efforts should focus on the interactions between predominant B. tabaci cryptic species and begomoviruses and on the development of effective control strategies. PMID:25502045

  8. Cryptic or pseudocryptic: can morphological methods inform copepod taxonomy? An analysis of publications and a case study of the Eurytemora affinis species complex

    Science.gov (United States)

    Lajus, Dmitry; Sukhikh, Natalia; Alekseev, Victor

    2015-01-01

    Interest in cryptic species has increased significantly with current progress in genetic methods. The large number of cryptic species suggests that the resolution of traditional morphological techniques may be insufficient for taxonomical research. However, some species now considered to be cryptic may, in fact, be designated pseudocryptic after close morphological examination. Thus the “cryptic or pseudocryptic” dilemma speaks to the resolution of morphological analysis and its utility for identifying species. We address this dilemma first by systematically reviewing data published from 1980 to 2013 on cryptic species of Copepoda and then by performing an in-depth morphological study of the former Eurytemora affinis complex of cryptic species. Analyzing the published data showed that, in 5 of 24 revisions eligible for systematic review, cryptic species assignment was based solely on the genetic variation of forms without detailed morphological analysis to confirm the assignment. Therefore, some newly described cryptic species might be designated pseudocryptic under more detailed morphological analysis as happened with Eurytemora affinis complex. Recent genetic analyses of the complex found high levels of heterogeneity without morphological differences; it is argued to be cryptic. However, next detailed morphological analyses allowed to describe a number of valid species. Our study, using deep statistical analyses usually not applied for new species describing, of this species complex confirmed considerable differences between former cryptic species. In particular, fluctuating asymmetry (FA), the random variation of left and right structures, was significantly different between forms and provided independent information about their status. Our work showed that multivariate statistical approaches, such as principal component analysis, can be powerful techniques for the morphological discrimination of cryptic taxons. Despite increasing cryptic species

  9. Two unusual cases of severe recalcitrant hypocalcemia due to aminoglycoside-induced hypomagnesemia

    Directory of Open Access Journals (Sweden)

    Tarun Varma

    2013-01-01

    Full Text Available Aminoglycoside (AMG-induced renal toxicity is well-known and may manifest with non-oliguric renal failure or renal tubular dysfunction like Fanconi-like syndrome, Barter syndrome-like syndrome or distal renal tubular acidosis (RTA. These phenomena have been described with Gentamycin and Amikacin though rarely with Kanamycin. We present two cases of pulmonary tuberculosis that were treated with Kanamycin and during the course of treatment, developed severe recalcitrant hypocalcemia along with hypomagnesemia.

  10. Aerial ULV control of Aedes aegypti with naled (Dibrom) inside simulated rural village and urban cryptic habitats.

    Science.gov (United States)

    Britch, Seth C; Linthicum, Kenneth J; Aldridge, Robert L; Breidenbaugh, Mark S; Latham, Mark D; Connelly, Peter H; Rush, Mattie J E; Remmers, Jennifer L; Kerce, Jerry D; Silcox, Charles A

    2018-01-01

    We conducted aerial fixed wing ultra low volume (ULV) spray trials with naled to investigate penetration of exposed and simulated cryptic habitat within opened buildings, partially sealed buildings, and outdoor locations targeting sentinel adult Aedes aegypti mosquitoes in north central Florida. Mortality was observed in open and closed buildings and outdoors, even in mosquitoes placed in cryptic habitats. Observations on the impact of building type, mosquito exposure method such as placement in cryptic habitat, and spray nozzle size on mosquito mortality are described and analyzed.

  11. DNA barcoding, ecology and geography of the cryptic species of Aneura pinguis and their relationships with Aneura maxima and Aneura mirabilis (Metzgeriales, Marchantiophyta).

    Science.gov (United States)

    Bączkiewicz, Alina; Szczecińska, Monika; Sawicki, Jakub; Stebel, Adam; Buczkowska, Katarzyna

    2017-01-01

    Aneura pinguis is a thalloid liverwort species with broad geographical distribution. It is composed of cryptic species, however, the number of cryptic species within A. pinguis is not known. Five cpDNA regions (matK, rbcL, rpoC1, trnH-psbA and trnL-trnF) and the entire nuclear ITS region were studied in 130 samples of A. pinguis from different geographical regions. The relationships between the cryptic species of A. pinguis, A. maxima and A. mirabilis were analyzed. All of the examined samples were clustered into 10 clades corresponding to 10 cryptic species of A. pinguis (marked A to J). Aneura mirabilis and A. maxima were nested among different cryptic species of A. pinguis, which indicates that A. pinguis is a paraphyletic taxon. Subgroups were found in cryptic species A, B, C and E. As single barcodes, all tested DNA regions had 100% discriminant power and fulfilled DNA barcode criteria for species identification; however, the only combination detected in all subgroups was trnL-trnF with trnH-psbA or ITS2. The distances between cryptic species were 11- to 35-fold higher than intraspecific distances. In all analyzed DNA regions, the distances between most pairs of cryptic A. pinguis species were higher than between A. maxima and A. mirabilis. All cryptic species of A. pinguis clearly differed in their habitat preferences, which suggests that habitat adaptation could be the main driving force behind cryptic speciation within this taxon.

  12. Assessment of antibiotic resistance genes and integrons in commensal Escherichia coli from the Indian urban waste water: Implications and significance for public health

    Directory of Open Access Journals (Sweden)

    Nambram Somendro Singh

    2017-10-01

    Full Text Available Antibiotics like β-lactams, quinolones/fluoroquinolones, aminoglycosides and tetracycline constitute the major mainstay of treatment against most infectious diseases including Escherichia coli. Indiscriminate use of antibiotics for human and animal well-being has generated an enormous evolutionary pressure on bacteria especially E.coli, which has a highly plastic/evolving genome. Though, antibiotic resistance (AR has been extensively studied in pathogenic E.coli, commensal strains have been studied less owing to lesser clinical significance. However, commensal strains pose a serious threat as reservoirs and transmitters of resistance genes to other bacteria. Therefore, the present study was undertaken to investigate the prevalence of resistance genes and integrons in commensal E.coli isolated from river Yamuna, Delhi, India, which receives plentiful urban waste water. Eighty three well-characterized E.coli strains of phylogroups A and B1 isolated from river Yamuna were investigated. Antimicrobial susceptibilities and minimal inhibitory concentrations (MICs for β-lactams, aminoglycosides, tetracycline and quinolone/fluoroquinolone were determined by disk diffusion and Etest, according to Clinical and Laboratory Standards Institute (CLSI guidelines. Production of Extended spectrum β-lactamases (ESBL and AmpC was investigated. Prevalence of antibiotic-resistance genes for β-lactams (blaTEM,blaSHV, blaCTX-M, blaOXA, blaCMY-42, aminoglycosides (rmtA, rmtB, rmtC, armA, str, aacC2, tetracycline (tetA, tetR, tetM, tetW, and plasmid-mediated quinolone resistance, PMQR (qnrA, qnrB, qnrC, qnrD, qnrS, qep, aac were assessed. Integrons and  gene-cassette arrays were characterized. Commensal E.coli strains showed a higher resistance to ampicillin (95%, less to cefazolin (45% and still lesser to tetracycline (15%. About 19% of these strains showed multidrug resistant (three or more classes of antibiotics, of which 15% also produced ESBLs. None of the

  13. New plasmid-mediated aminoglycoside 6'-N-acetyltransferase, AAC(6')-Ian, and ESBL, TLA-3, from a Serratia marcescens clinical isolate.

    Science.gov (United States)

    Jin, Wanchun; Wachino, Jun-Ichi; Kimura, Kouji; Yamada, Keiko; Arakawa, Yoshichika

    2015-05-01

    Enterobacteriaceae clinical isolates showing amikacin resistance (MIC 64 to >256 mg/L) in the absence of 16S rRNA methyltransferase (MTase) genes were found. The aim of this study was to clarify the molecular mechanisms underlying amikacin resistance in Enterobacteriaceae clinical isolates that do not produce 16S rRNA MTases. PCR was performed to detect already-known amikacin resistance determinants. Cloning experiments and sequence analyses were performed to characterize unknown amikacin resistance determinants. Transfer of amikacin resistance determinants was performed by conjugation and transformation. The complete nucleotide sequence of the plasmids was determined by next-generation sequencing technology. Amikacin resistance enzymes were purified with a column chromatography system. The enzymatic function of the purified protein was investigated by thin-layer chromatography (TLC) and HPLC. Among the 14 isolates, 9 were found to carry already-known amikacin resistance determinants such as aac(6')-Ia and aac(6')-Ib. Genetic analyses revealed the presence of a new amikacin acetyltransferase gene, named aac(6')-Ian, located on a 169 829 bp transferable plasmid (p11663) of the Serratia marcescens strain NUBL-11663, one of the five strains negative for known aac(6') genes by PCR. Plasmid p11663 also carried a novel ESBL gene, named blaTLA-3. HPLC and TLC analyses demonstrated that AAC(6')-Ian catalysed the transfer of an acetyl group from acetyl coenzyme A onto an amine at the 6'-position of various aminoglycosides. We identified aac(6')-Ian as a novel amikacin resistance determinant together with a new ESBL gene, blaTLA-3, on a transferable plasmid of a S. marcescens clinical isolate. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Firefly luciferase gene contains a cryptic promoter

    Czech Academy of Sciences Publication Activity Database

    Vopálenský, V.; Mašek, T.; Horváth, Ondřej; Vicenová, B.; Mokrejš, M.; Pospíšek, M.

    2008-01-01

    Roč. 14, č. 9 (2008), s. 1720-1729 ISSN 1355-8382 Grant - others:GAČR(CZ) GA204/03/1487; GAČR(CZ) GA301/07/0607; Mšk(CZ) LC06066 Program:LC Institutional research plan: CEZ:AV0Z50520514 Keywords : luciferase * cryptic promoter * hepatitis C virus Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.018, year: 2008

  15. Mitochondrial phylogeny of grey mullets (Acanthopterygii: Mugilidae) suggests high proportion of cryptic species.

    Science.gov (United States)

    Durand, Jean-Dominique; Borsa, Philippe

    2015-04-01

    The low level of morphometric variability and the poor phylogenetic information borne by the morpho-anatomical characters used thus far in the systematics of grey mullets (Mugilidae) emphasize the utility of molecular systematics in this family. A recent mitochondrial phylogeny of grey mullets has uncovered multiple deep lineages within several species, flagging putative cryptic species. Here, we considered that several of the deeply divergent lineages represent separate species based on either the tree topology, independent data from nuclear markers, geographic distributions, or a combination of the foregoing. By analogy with these well-documented cases, we considered other deep lineages in seven genera we focused on to represent putative cryptic species. Up to two cryptic species were thus potentially detected in the genus Chelon, three in Crenimugil (including two within the single Crenimugil seheli), two in Dajaus, one in Ellochelon, 16 in Mugil (including 13 within the single M. cephalus), two in Osteomugil, and 10 in Planiliza. Wherever possible, we kept the current species epithets to designate those lineages that unambiguously correspond to the type material, based on type locality, and we assigned arbitrary letters (sp. A, B, etc.) to the other lineages. We present a molecular diagnosis for 24 of the species analysed in this work, as well as for 25 putative cryptic species. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  16. Conjugal transfer of aac(6')Ie-aph(2″)Ia gene from native species and mechanism of regulation and cross resistance in Enterococcus faecalis MCC3063 by real time-PCR.

    Science.gov (United States)

    Jaimee, G; Halami, P M

    2017-09-01

    High level aminoglycoside resistance (HLAR) in the lactic acid bacteria (LAB) derived from food animals is detrimental. The aim of this study was to investigate the localization and conjugal transfer of aminoglycoside resistance genes, aac(6')Ie-aph(2″)Ia and aph(3')IIIa in different Enterococcus species. The cross resistance patterns in Enterococcus faecalis MCC3063 to clinically important aminoglycosides by real time PCR were also studied. Southern hybridization experiments revealed the presence of aac(6')Ie-aph(2 ″ )Ia and aph(3')IIIa genes conferring HLAR in high molecular weight plasmids except in Lactobacillus plantarum. The plasmid encoded bifunctional aac(6')Ie-aph(2″)Ia gene was transferable from Enterococcus avium (n = 2), E. cecorum (n = 1), E. faecalis (n = 1) and Pediococcus lolii (n = 1) species into the recipient strain; E. faecalis JH2-2 by filter mating experiments thus indicating the possible risks of gene transfer into pathogenic strains. Molecular analysis of cross resistance patterns in native isolate of E. faecalis MCC3063 carrying aac(6')Ie-aph(2″)Ia and aph(3')IIIa gene was displayed by quantification of the mRNA levels in this study. For this, the culture was induced with increasing concentrations of gentamicin, kanamycin and streptomycin (2048, 4096, 8192, 16384 μg/mL) individually. The increasing concentrations of gentamicin and kanamycin induced the expression of the aac(6')Ie-aph(2″)Ia and aph(3')IIIa resistance genes, respectively. Interestingly, it was observed that induction with streptomycin triggered a significant fold increase in the expression of the aph(3')IIIa gene which otherwise was not known to modify the aminoglycoside. This is noteworthy as streptomycin was found to confer cross resistance to structurally unrelated kanamycin. Also, expression of the aph(3')IIIa gene when induced with streptomycin, revealed that bacteria harbouring this gene will be able to overcome streptomycin bactericidal action at

  17. Pan Drug-Resistant Environmental Isolate of Acinetobacter baumannii from Croatia.

    Science.gov (United States)

    Goic-Barisic, Ivana; Seruga Music, Martina; Kovacic, Ana; Tonkic, Marija; Hrenovic, Jasna

    2017-06-01

    Acinetobacter baumannii is an emerging nosocomial pathogen with also emerging resistance to different antibiotics. Multidrug and pan drug-resistant clinical isolates were reported worldwide. Here we report the first evidence of pan drug-resistant environmental isolate of A. baumannii. The isolate was recovered from the effluent of secondary treated municipal wastewater of the City of Zagreb, Croatia. The isolate was resistant to penicillins/β-lactamase inhibitors, carbapenems, fluoroquinolones, aminoglycosides, folate pathway inhibitors, and polymyxins, except intermediately susceptible to minocycline and tigecycline. Intrinsic chromosomally located bla OXA-51-like gene and acquired plasmid-located bla OXA-23-like gene were related to clinical isolates. Pan drug-resistant A. baumannii can occur in natural environments outside of the hospital. Secondary treated municipal wastewater represents a potential epidemiological reservoir of pan drug-resistant A. baumannii and carbapenem resistance gene.

  18. Cryptic diversity in the Japanese mantis shrimp Oratosquilla oratoria (Crustacea: Squillidae): Allopatric diversification, secondary contact and hybridization.

    Science.gov (United States)

    Cheng, Jiao; Sha, Zhong-Li

    2017-05-16

    Mounting evidence of cryptic species in the marine realm emphasizes the necessity to thoroughly revise our current perceptions of marine biodiversity and species distributions. Here, we used mitochondrial cytochrome oxidase subunit I (mtDNA COI) and nuclear ribosomal internal transcribed spacer (nrDNA ITS) to investigate cryptic diversity and potential hybridization in the Japanese mantis shrimp Oratosquilla oratoria in the Northwestern (NW) Pacific. Both mitochondrial and nuclear gene genealogies revealed two cryptic species in this morphotaxon, which was further confirmed by extensive population-level analyses. One cryptic species is restricted to cold waters with a distribution range corresponding to temperate affinities, while the other dwelled warm waters influenced by the Kuroshio Current. Their divergence was postulated to be attributable to the vicariant event which resulted from the isolation of the Sea of Japan during the middle Pliocene (c. 3.85 Mya, 95% HPD 2.23-6.07 Mya). Allopatric speciation was maintained by limited genetic exchange due to their habitat preferences. Furthermore, the observation of recombinant nrDNA ITS sequence and intra-individual ITS polymorphism suggested recent hybridization event of the two cryptic species occurred in sympatric areas. Our study also illustrated that the Changjiang River outflow might act as an oceanic barrier to gene flow and promoted allopatric diversification in O. oratoria species complex.

  19. Rapid increase in resistance to third generation cephalosporins, imipenem and co-resistance in Klebsiella pneumoniae from isolated from 7,140 blood-cultures (2010-2014) using EARS-Net data in Spain.

    Science.gov (United States)

    Aracil-García, Belén; Oteo-Iglesias, Jesús; Cuevas-Lobato, Óscar; Lara-Fuella, Noelia; Pérez-Grajera, Isabel; Fernández-Romero, Sara; Pérez-Vázquez, María; Campos, José

    2017-10-01

    An analysis was made about the evolution of resistance to 3rd generation cephalosporins, imipenem, and other antibiotics in invasive isolates of Klebsiella pneumoniae (K. pneumoniae) according to the Spanish EARS-Net database (2010-2014). Forty-two hospitals from 16 Autonomous Communities with an approximate population coverage of 33% participated. A total 7,140 pneumoniae corresponding to the same number of patients were studied. Overall resistance percentages (I+R) were: cefotaxime 15.8%, ceftazidime 13.7%, imipenem 1.7%, ciprofloxacin 20.1%, tobramycin 14.1%, gentamicin 10.4%, and amikacin 1.9%. Resistance to 3rd generation cephalosporins increased from 9.8% (2010) to 19% (2014); to ciprofloxacin from 15.4% (2010) to 19.6% (2014); to gentamicin from 6.2% (2010) to 10.3% (2014) and to tobramycin from 7.1% (2010) to 14.2% (2014) (presistance to 3rd generation cephalosporins, ciprofloxacin, and aminoglycosides increased from 3.3% (2010) to 9.7% (2014) (pResistance to imipenem also increased from 0.27% (2010) to 3.46% (2014) (presistant to imipenem, of which 104 (86%) produced carbapenemases: 74 OXA-48, 14 VIM, 9 KPC (6 KPC-2 and 3 KPC-3), 6 IMP, and 1 GES. Over the 5 year period (2010-2014), resistance to 3rd generation cephalosporins in invasive K. pneumoniae in Spain has doubled. The combined resistance to 3rd generation cephalosporins, ciprofloxacin, and aminoglycosides has tripled, and imipenem resistance has increased almost 13 times, mostly due to the spread of carbapenemase-producing isolates. Copyright © 2016 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  20. Antifungal amphiphilic aminoglycoside K20: bioactivities and mechanism of action

    Directory of Open Access Journals (Sweden)

    Sanjib K. Shrestha

    2014-12-01

    Full Text Available K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20’s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid vesicles. K20 exhibited broad-spectrum in vitro antifungal activities but not antibacterial activities. Pulmonary, single dose-administration of K20 reduced C. neoformans lung infection rates 4-fold compared to controls. Hemolysis and half-maximal cytotoxicities of mammalian cells occurred at concentrations that were 10 to 32-fold higher than fungicidal MICs. With fluorescein isothiocyanate, 20 to 25 mg/L K20 caused staining of >95% of C. neoformans and Fusarium graminearum cells and at 31.3 mg/L caused rapid leakage (30 to 80% in 15 min of calcein from preloaded small unilamellar lipid vesicles. K20 appears to be a broad-spectrum fungicide, capable of reducing the infectivity of C. neoformans, and exhibits low hemolytic activity and mammalian cell toxicity. It perturbs the plasma membrane by mechanisms that are lipid modulated. K20 is a novel amphiphilic aminoglycoside amenable to scalable production and a potential lead antifungal for therapeutic and crop protection applications.

  1. Azobenzene-aminoglycoside: Self-assembled smart amphiphilic nanostructures for drug delivery.

    Science.gov (United States)

    Deka, Smriti Rekha; Yadav, Santosh; Mahato, Manohar; Sharma, Ashwani Kumar

    2015-11-01

    Here, we have designed and synthesized a novel cationic amphiphilic stimuli-responsive azobenzene-aminoglycoside (a small molecule) conjugate, Azo-AG 5, and characterized it by UV and FTIR. Light responsive nature of Azo-AG 5 was assessed under UV-vis light. Self- assembly of Azo-AG 5 in aqueous solutions into nanostructures and their ability to act as drug carrier were also investigated. The nanostructures of Azo-AG 5 showed average hydrodynamic diameter of ∼ 255 nm with aminoglycoside moiety (neomycin) and 4-dimethylaminoazobenzene forming hydrophilic shell and hydrophobic core, respectively. In the hydrophobic core, eosin and aspirin were successfully encapsulated. Dynamic light scattering (DLS) measurements demonstrated that the nanoassemblies showed expansion and contraction on successive UV and visible light irradiations exhibiting reversible on-off switch for controlling the drug release behavior. Similar behavior was observed when these nanostructures were subjected to pH-change. In vitro drug release studies showed a difference in UV and visible light-mediated release pattern. It was observed that the release rate under UV irradiation was comparatively higher than that observed under visible light. Further, azoreductase-mediated cleavage of the azo moiety in Azo-AG 5 nanoassemblies resulted in the dismantling of the structures into aggregated microstructures. Azo-AG 5 nanostructures having positive surface charge (+9.74 mV) successfully interacted with pDNA and retarded its mobility on agarose gel. Stimuli responsiveness of nanostructures and their on-off switch like behavior ensure the great potential as controlled drug delivery systems and in other biomedical applications such as colon-specific delivery and gene delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Minimized state complexity of quantum-encoded cryptic processes

    Science.gov (United States)

    Riechers, Paul M.; Mahoney, John R.; Aghamohammadi, Cina; Crutchfield, James P.

    2016-05-01

    The predictive information required for proper trajectory sampling of a stochastic process can be more efficiently transmitted via a quantum channel than a classical one. This recent discovery allows quantum information processing to drastically reduce the memory necessary to simulate complex classical stochastic processes. It also points to a new perspective on the intrinsic complexity that nature must employ in generating the processes we observe. The quantum advantage increases with codeword length: the length of process sequences used in constructing the quantum communication scheme. In analogy with the classical complexity measure, statistical complexity, we use this reduced communication cost as an entropic measure of state complexity in the quantum representation. Previously difficult to compute, the quantum advantage is expressed here in closed form using spectral decomposition. This allows for efficient numerical computation of the quantum-reduced state complexity at all encoding lengths, including infinite. Additionally, it makes clear how finite-codeword reduction in state complexity is controlled by the classical process's cryptic order, and it allows asymptotic analysis of infinite-cryptic-order processes.

  3. Genomic Analysis Reveals Distinct Concentration-Dependent Evolutionary Trajectories for Antibiotic Resistance in Escherichia coli

    Science.gov (United States)

    Mogre, Aalap; Sengupta, Titas; Veetil, Reshma T.; Ravi, Preethi; Seshasayee, Aswin Sai Narain

    2014-01-01

    Evolution of bacteria under sublethal concentrations of antibiotics represents a trade-off between growth and resistance to the antibiotic. To understand this trade-off, we performed in vitro evolution of laboratory Escherichia coli under sublethal concentrations of the aminoglycoside kanamycin over short time durations. We report that fixation of less costly kanamycin-resistant mutants occurred earlier in populations growing at lower sublethal concentration of the antibiotic, compared with those growing at higher sublethal concentrations; in the latter, resistant mutants with a significant growth defect persisted longer. Using deep sequencing, we identified kanamycin resistance-conferring mutations, which were costly or not in terms of growth in the absence of the antibiotic. Multiple mutations in the C-terminal end of domain IV of the translation elongation factor EF-G provided low-cost resistance to kanamycin. Despite targeting the same or adjacent residues of the protein, these mutants differed from each other in the levels of resistance they provided. Analysis of one of these mutations showed that it has little defect in growth or in synthesis of green fluorescent protein (GFP) from an inducible plasmid in the absence of the antibiotic. A second class of mutations, recovered only during evolution in higher sublethal concentrations of the antibiotic, deleted the C-terminal end of the ATP synthase shaft. This mutation confers basal-level resistance to kanamycin while showing a strong growth defect in the absence of the antibiotic. In conclusion, the early dynamics of the development of resistance to an aminoglycoside antibiotic is dependent on the levels of stress (concentration) imposed by the antibiotic, with the evolution of less costly variants only a matter of time. PMID:25281544

  4. A case of aminoglycosides induced retinal toxicity treated with megadoses of steroids and an intravitreal dexamethasone implant (Ozurdex(®)).

    Science.gov (United States)

    Hernández Pardines, F; Tapia-Quijada, H; Hueso-Abancens, J R

    2016-06-01

    The case is described of a patient who had a sudden loss of vision in her right eye after glaucoma surgery. A diagnosis of retinal toxicity due to tobramycin (an aminoglycoside) was reached, which was characterised by retinal whitening with a red cherry stain, macular oedema, and vasculitis that progressed to papillary and macular atrophy with arteriolar sclerosis. Given the severity of symptoms an early attempt was made with megadoses of steroids and an intravitreal dexamethasone implant (Ozurdex®, Allergan S.A.), without response. Aminoglycoside toxicity is a rare, idiosyncratic, very serious complication for which there is no effective treatment. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  5. Complexation of anionic copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide with aminoglycoside antibiotics

    Science.gov (United States)

    Solovskii, M. V.; Tarabukina, E. B.; Amirova, A. I.; Zakharova, N. V.; Smirnova, M. Yu.; Gavrilova, I. I.

    2014-03-01

    The complexation of aminoglycoside antibiotics neomycin, gentamicin, kanamycin, and amikacin in the form of free bases with carboxyl- and sulfo-containing copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide (HPMA) in water and water-salt solutions is studied by means of viscometry, equilibrium dialysis, potentiometric titration, and molecular hydrodynamics. Factors influencing the stability of formed copolymer-antibiotic complexes and determinations of their toxicity are established.

  6. Antimicrobial resistance mechanisms among Campylobacter.

    Science.gov (United States)

    Wieczorek, Kinga; Osek, Jacek

    2013-01-01

    Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed.

  7. Cryptic sexual size dimorphism in Malagasy plovers Charadrius spp ...

    African Journals Online (AJOL)

    Taken together, our work reports SSD in small African plovers that exhibit monomorphic plumage, and we propose that SSD may be more common than currently acknowledged; we term this 'cryptic sexual size dimorphism'. Our results also suggest sexual selection and/or natural selection exert different pressures on body ...

  8. Seven new species of Oculatella (Pseudanabaenales, Cyanobacteria): taxonomically recognizing cryptic diversification

    Czech Academy of Sciences Publication Activity Database

    Osorio-Santos, K.; Pietrasiak, N.; Bohunická, Markéta; Miscoe, L. H.; Kováčik, L.; Martin, M.P.; Johansen, J. R.

    2014-01-01

    Roč. 49, č. 4 (2014), s. 450-470 ISSN 0967-0262 Institutional support: RVO:67985939 Keywords : cryptic species * cyanobacteria * Pseudanabaenaceae Subject RIV: EF - Botanics Impact factor: 1.912, year: 2014

  9. Familial cryptic translocation in Angelman syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Weyerts, L.K.; Wiley, J.E.; Loud, K.M. [ECU School of Medicine, Greenville, NC (United States)] [and others

    1994-09-01

    The majority of patients with Angelman syndrome have been shown to have a cytogenetic or molecular deletion on the maternally derived chromosome 15. We report on a case of Angelman syndrome in which this deletion occurs as an unbalanced cryptic translocation involving chromosomes 14 and 15. The proband was diagnosed clinically as having Angelman syndrome. Multiple cytogenetic studies were done without detecting any deletion. When DNA probes (Oncor) specific for the Prader Willi/Angelman locus became available, the patient was restudied and found to be deleted for {open_quotes}region A{close_quotes} (D15S11) but not for {open_quotes}region B{close_quotes} (GABRB3). No other abnormality was detected. The proband`s mother was then studied. The chromosome 15 marker probe and D15S11 were detected on different chromosomes. Using alpha-satellite probes, a cryptic 14;15 translocation was uncovered. This balanced translocation was also found to be carried by the sister of the proband. This case, along with a case presented at the 1993 ASHG meeting, illustrates the need for using acrocentric probes when studying Angelman syndrome patients. The proband was studied using additional probes specific for this region and found to be deleted for SNRPN but not for D15S10. The breakpoint of the translocation in this patient delineates the smallest deletion of the Angelman syndrome region reported to date and therefore may represent the specific gene involved.

  10. Antibiotic resistance profile of Pseudomonas aeruginosa isolated from aquaculture and abattoir environments in urban communities

    Directory of Open Access Journals (Sweden)

    Isoken Henrietta Igbinosa

    2017-01-01

    Full Text Available Objective: To characterize multiple antibiotic resistance profile of Pseudomonas aeruginosa from aquaculture and abattoir environments. Methods: Wastewater samples were obtained from the abattoir and aquaculture environments between May 2016 and July 2016 and analysed using standard phenotypic, biochemical and PCR-based methods. Results: The mean pseudomonads count ranged from (4 × 102 ± 1.01 to (2 × 104 ± 0.10 colony-forming unit/mL in the aquaculture environment and (3 × 103 ± 0.00 to (1 × 105 ± 1.00 colony-forming unit/mL in the abattoir environment. A total of 96 isolates of Pseudomonas aeruginosa confirmed by PCR were thereafter selected from both aquaculture and abattoir environments and further characterized for their antimicrobial susceptibility profile by adopting the disc diffusion method. High level of resistance was observed against the aminoglycosides [gentamycin 64/96 (66.67% and kanamycin 52/96 (54.17%], monobactams [aztreonam 76/96 (79.17%], carbapenems [meropenem 52/96 (54.17%], tetracyclines [tetracycline 72/96 (75.00%] and cephems [ceftazidime 72/96 (75.00% and cefuroxime 48/96 (50.00%]. Multiple antibiotic resistant index of the respective isolates ranged from 0.4 to 0.8 while multidrug resistant profile of the isolates revealed that 28 of the respective isolates were resistant to ceftazidime, cefuroxime, gentamycin, kanamycin, aztreonam which belongs to cephems, aminoglycosides and monobactam class of antimicrobials. Conclusions: Findings from the present study therefore underscores the need for effective monitoring of the abattoir and aquaculture environments as they could be the significant source for spreading antibiotic resistant bacteria within the environment.

  11. Antibiotic resistance patterns of pediatric community-acquired urinary infections

    Directory of Open Access Journals (Sweden)

    Eliana Biondi Medeiros Guidoni

    Full Text Available Knowledge about antimicrobial resistance patterns of the etiological agents of urinary tract infections (UTIs is essential for appropriate therapy. Urinary isolates from symptomatic UTI cases attended at Santa Casa University Hospital of São Paulo from August 1986 to December 1989 and August 2004 to December 2005 were identified by conventional methods. Antimicrobial resistance testing was performed by Kirby Bauer's disc diffusion method. Among the 257 children, E. coli was found in 77%. A high prevalence of resistance was observed against ampicillin and TMP/SMX (55% and 51%. The antibiotic resistance rates for E. coli were: nitrofurantoin (6%, nalidixic acid (14%, 1st generation cephalosporin (13%, 3rd generation cephalosporins (5%, aminoglycosides (2%, norfloxacin (9% and ciprofloxacin (4%. We found that E. coli was the predominant bacterial pathogen of community-acquired UTIs. We also detected increasing resistance to TMP/SMX among UTI pathogens in this population.

  12. Reduction of excess sludge in a sequencing batch reactor by lysis-cryptic growth using quick lime for disintegration under low temperature.

    Science.gov (United States)

    Lv, Xiao-Mei; Song, Ju-Sheng; Li, Ji; Zhai, Kun

    2017-08-01

    In the present study, quick-lime-based thermal-alkaline sludge disintegration (SD) under low temperature was combined with cryptic growth to investigate the excess sludge reduction efficiency in the sequencing batch reactor (SBR). The optimized condition of SD was as follows: T = 80℃, pH = 11, t = 180 min, and the SD rate was about 42.1%. With 65.6% of excess sludge disintegrated and returned to the SBR, the system achieved sludge reduction rate of about 40.1%. The lysis-cryptic growth still obtained satisfactory sludge reduction efficiency despite the comparative low SD rate, which suggested that disintegration rate might not be the decisive factor for cryptic-growth-based sludge reduction. Lysis-cryptic growth did not impact the effluent quality, yet the phosphorus removal performance was enhanced, with effluent total phosphorus concentration decreased by 0.3 mg/L (33%). Crystal compounds of calcium phosphate precipitate were detected in the system by Fourier transform infrared spectroscopy and X-ray diffraction, which indicated the phosphorus removal potential of SD using lime. Moreover, endogenous dehydrogenase activity of activated sludge in the lysis-cryptic system was enhanced, which was beneficial for sludge reduction. SD and cryptic growth in the present study demonstrates an economical and effective approach for sludge reduction.

  13. Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

    Science.gov (United States)

    Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

    2017-03-01

    An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Complete genome sequence analysis of the fish pathogen Flavobacterium columnare provides insights into antibiotic resistance and pathogenicity related genes.

    Science.gov (United States)

    Zhang, Yulei; Zhao, Lijuan; Chen, Wenjie; Huang, Yunmao; Yang, Ling; Sarathbabu, V; Wu, Zaohe; Li, Jun; Nie, Pin; Lin, Li

    2017-10-01

    We analyzed here the complete genome sequences of a highly virulent Flavobacterium columnare Pf1 strain isolated in our laboratory. The complete genome consists of a 3,171,081 bp circular DNA with 2784 predicted protein-coding genes. Among these, 286 genes were predicted as antibiotic resistance genes, including 32 RND-type efflux pump related genes which were associated with the export of aminoglycosides, indicating inducible aminoglycosides resistances in F. columnare. On the other hand, 328 genes were predicted as pathogenicity related genes which could be classified as virulence factors, gliding motility proteins, adhesins, and many putative secreted proteases. These genes were probably involved in the colonization, invasion and destruction of fish tissues during the infection of F. columnare. Apparently, our obtained complete genome sequences provide the basis for the explanation of the interactions between the F. columnare and the infected fish. The predicted antibiotic resistance and pathogenicity related genes will shed a new light on the development of more efficient preventional strategies against the infection of F. columnare, which is a major worldwide fish pathogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. High-throughput sequencing offers insight into mechanisms of resource partitioning in cryptic bat species

    DEFF Research Database (Denmark)

    Razgour, Orly; Clare, Elizabeth L.; Zeale, Matt R. K.

    2011-01-01

    Sympatric cryptic species, characterized by low morphological differentiation, pose a challenge to understanding the role of interspecific competition in structuring ecological communities. We used traditional (morphological) and novel molecular methods of diet analysis to study the diet of two...... of the cryptic bats, 60% of which were assigned to a likely species or genus. The findings from the molecular study supported the results of microscopic analyses in showing that the diets of both species were dominated by lepidopterans. However, HTS provided a sufficiently high resolution of prey identification...

  16. Antibiotic sensitivity and resistance in children with urinary tract infection in Sanliurfa.

    Science.gov (United States)

    Abuhandan, Mahmut; Güzel, Bülent; Oymak, Yeşim; Çiftçi, Halil

    2013-06-01

    This study aimed to evaluate antibiotic resistance in the province of Şanliurfa and to observe any difference between antibiotic resistance rates. The study comprised 107 children who presented at the pediatric polyclinic with complaints of urinary tract infection with the diagnosis of urinary tract infection and whose urine cultures exhibited bacterial growth. The patients were analyzed with respect to the frequency of proliferating pathogens, sensitivity to the antibiotics used and the rates of developed resistance to the antibiotics. A total of 107 patients aged between 1 year and 15 years were included in the study, encompassing 14 (13.1%) males and 93 (86.9%) females. According to the urine culture results, proliferation of Escherichia coli (E. coli) was observed in 69 (64.5%), Klebsiella spp. in 13 (12.1%), Proteus mirabilis in 9 (8.4%), Staphylococcus aureus in 5 (4.7%), Pseudomonas aeruginosa in 5 (4.7%), Acinetobacter spp. in 3 (2.8%) and Enterococcus spp. in 3 (2.8%) patients. For proliferating E. coli, high resistance rates to ceftriaxone (39.5%), nitrofurantoin (19.7%), ampicillin-sulbactam (64.1%), co-trimoxazole (41.5%), amoxicillinclavulanate (51.7%) and cefuroxime (38.1%) were observed. All of isolated microorganisms were resistant to ampicillin-sulbactam, amoxicillin-clavulanate, co-trimoxazole, ceftriaxone, cefuroxime and cefoxitin in decreasing frequencies. The most effective antimicrobial agents were determined to be imipenem, sulpera-zone, quinolone and aminoglycosides. In our region, parenteral antibiotics that should be selected for the empirical treatment of UTIs in all age groups are the aminoglycosides and 3(rd) generation cephalosporines. In contrast to other studies, these results suggest that co-trimoxazole should be used for children aged 0-1, and 2(nd) generation cephalosporins should be used for the oral treatment of children aged 1-5 due to the low rate of resistance to nitrofurantoin in patients aged over 5 years.

  17. Contrasting patterns of population structure and demographic history in cryptic species of Bostrychia intricata (Rhodomelaceae, Rhodophyta) from New Zealand.

    Science.gov (United States)

    Muangmai, Narongrit; Fraser, Ceridwen I; Zuccarello, Giuseppe C

    2015-06-01

    Spatial patterns of genetic diversity provide insight into the demography and history of species. Morphologically similar but genetically distinct "cryptic" species are increasingly being recognized in marine organisms through molecular analyses. Such species are, on closer inspection, often discovered to display contrasting life histories or occasionally minor morphological differences; molecular tools can thus be useful indicators of diversity. Bostrychia intricata, a marine red alga, is widely distributed throughout the Southern Hemisphere and comprises many cryptic species. We used mitochondrial cytochrome c oxidase I gene sequences to assess the genetic variation, population genetic structure, and demographic history of B. intricata in New Zealand. Our results supported the existence of three cryptic species of B. intricata (N2, N4, and N5) in New Zealand. Cryptic species N4, which was found throughout New Zealand, showed a higher genetic diversity and wider distribution than the other two species, which were only found in the North Island and northern South Island. Our analyses showed low to moderate genetic differentiation among eastern North Island populations for cryptic species N2, but high differentiation among North and South Island populations for N4, suggesting different population structure between these cryptic species. Data also indicated that N2 has recently undergone population expansion, probably since the Last Glacial Maximum (LGM), while the higher genetic diversity in N4 populations suggests persistence in situ through the LGM. The contrasting population structures and inferred demographic histories of these species highlight that life history can vary greatly even among morphologically indistinguishable taxa. © 2015 Phycological Society of America.

  18. In Vitro Synergistic Effects of Double and Triple Combinations of β-Lactams, Vancomycin, and Netilmicin against Methicillin-Resistant Staphylococcus aureus Strains

    Science.gov (United States)

    Rochon-Edouard, Stéphanie; Pestel-Caron, Martine; Lemeland, Jean-François; Caron, François

    2000-01-01

    Several studies have previously reported synergistic effects between vancomycin and a given β-lactam or a given aminoglycoside against methicillin-resistant Staphylococcus aureus (MRSA) strains. The aim of our study was to exhaustively compare the effects of different combinations of a β-lactam, vancomycin, and/or an aminoglycoside against 32 clinical MRSA strains with different aminoglycoside susceptibility patterns. The effects of 26 different β-lactam–vancomycin and 8 different aminoglycoside-vancomycin combinations were first studied using a disk diffusion screening method. The best interactions with vancomycin were observed with either imipenem, cefazolin, or netilmicin. By checkerboard studies, imipenem-vancomycin and cefazolin-vancomycin each provided a synergistic bacteriostatic effect against 22 strains; the mean fractional inhibitory concentration (FIC) indexes were 0.35 and 0.46 for imipenem-vancomycin and cefazolin-vancomycin, respectively. The vancomycin-netilmicin combination provided an indifferent effect against all of the 32 strains tested; the mean of FIC index was 1.096. The mean concentrations of imipenem, cefazolin, netilmicin, and vancomycin at which FIC indexes were calculated were clinically achievable. Killing experiments were then performed using imipenem, cefazolin, netilmicin, and vancomycin at one-half of the MIC, alone and in different combinations, against 10 strains. The vancomycin-netilmicin regimen was rarely bactericidal, even against strains susceptible to netilmicin. The imipenem-vancomycin and cefazolin-vancomycin combinations were strongly bactericidal against six and five strains, respectively. The addition of netilmicin markedly enhanced the killing activity of the combination of cefazolin or imipenem plus vancomycin, but only for the MRSA strains against which the β-lactam–vancomycin combinations had no bactericidal effect. It is noteworthy that the latter strains were both susceptible to netilmicin and

  19. Predation cues rather than resource availability promote cryptic behaviour in a habitat-forming sea urchin.

    Science.gov (United States)

    Spyksma, Arie J P; Taylor, Richard B; Shears, Nick T

    2017-03-01

    It is well known that predators often influence the foraging behaviour of prey through the so-called "fear effect". However, it is also possible that predators could change prey behaviour indirectly by altering the prey's food supply through a trophic cascade. The predator-sea urchin-kelp trophic cascade is widely assumed to be driven by the removal of sea urchins by predators, but changes in sea urchin behaviour in response to predators or increased food availability could also play an important role. We tested whether increased crevice occupancy by herbivorous sea urchins in the presence of abundant predatory fishes and lobsters is a response to the increased risk of predation, or an indirect response to higher kelp abundances. Inside two New Zealand marine reserves with abundant predators and kelp, individuals of the sea urchin Evechinus chloroticus were rarer and remained cryptic (i.e. found in crevices) to larger sizes than on adjacent fished coasts where predators and kelp are rare. In a mesocosm experiment, cryptic behaviour was induced by simulated predation (the addition of crushed conspecifics), but the addition of food in the form of drift kelp did not induce cryptic behaviour. These findings demonstrate that the 'fear' of predators is more important than food availability in promoting sea urchin cryptic behaviour and suggest that both density- and behaviourally mediated interactions are important in the predator-sea urchin-kelp trophic cascade.

  20. Resistance to K. pneumoniae in young children with congenital heart defects

    Directory of Open Access Journals (Sweden)

    V. N. Ilina

    2015-10-01

    Full Text Available Klebsiella pneumoniae is one of the leading agents of nosocomial infections (NI. In Russia, Klebsiella pneumoniae is the third in frequency of gram-negative pathogen NI. For a long time one of the major clinically relevant mechanisms of acquired resistance to K. pneumoniae is multidrug resistance caused by extended spectrum -lactamase production (ESBL. Carbapenems show the greatest resistance to the action of ESB. However, now there exist registered strains of K.pneumoniae resistant to carbapenems. In connection with this in 2008 we conducted a prospective study on resistance to K. pneumoniae in young children being treated at ICU. It was found out that resistance to III-IV-generation cephalosporines, fluoroquinolones, aminoglycosides is determined by production of ESBL, while resistance to carbapenems occurs due to reduction of permeability of cell membranes, in combination with production of ESBL. Some features of patients colonized with multidrug-resistant strains of K. pneumoniae are described.

  1. Cryptic Plutella species show deep divergence despite the capacity to hybridize.

    Science.gov (United States)

    Perry, Kym D; Baker, Gregory J; Powis, Kevin J; Kent, Joanne K; Ward, Christopher M; Baxter, Simon W

    2018-05-29

    Understanding genomic and phenotypic diversity among cryptic pest taxa has important implications for the management of pests and diseases. The diamondback moth, Plutella xylostella L., has been intensively studied due to its ability to evolve insecticide resistance and status as the world's most destructive pest of brassicaceous crops. The surprise discovery of a cryptic species endemic to Australia, Plutella australiana Landry & Hebert, raised questions regarding the distribution, ecological traits and pest status of the two species, the capacity for gene flow and whether specific management was required. Here, we collected Plutella from wild and cultivated brassicaceous plants from 75 locations throughout Australia and screened 1447 individuals to identify mtDNA lineages and Wolbachia infections. We genotyped genome-wide SNP markers using RADseq in coexisting populations of each species. In addition, we assessed reproductive compatibility in crossing experiments and insecticide susceptibility phenotypes using bioassays. The two Plutella species coexisted on wild brassicas and canola crops, but only 10% of Plutella individuals were P. australiana. This species was not found on commercial Brassica vegetable crops, which are routinely sprayed with insecticides. Bioassays found that P. australiana was 19-306 fold more susceptible to four commonly-used insecticides than P. xylostella. Laboratory crosses revealed that reproductive isolation was incomplete but directionally asymmetric between the species. However, genome-wide nuclear SNPs revealed striking differences in genetic diversity and strong population structure between coexisting wild populations of each species. Nuclear diversity was 1.5-fold higher in P. australiana, yet both species showed limited variation in mtDNA. Infection with a single Wolbachia subgroup B strain was fixed in P. australiana, suggesting that a selective sweep contributed to low mtDNA diversity, while a subgroup A strain infected just 1

  2. Human Health Hazards from Antimicrobial-Resistant Escherichia coli of Animal Origin

    DEFF Research Database (Denmark)

    Hammerum, A. M.; Heuer, Ole Eske

    2009-01-01

    of antimicrobial agents in food animals may add to the burden of antimicrobial resistance in humans. Bacteria from the animal reservoir that carry resistance to antimicrobial agents that are regarded as highly or critically important in human therapy (e.g., aminoglycosides, fluoroquinolones, and third- and fourth......Because of the intensive use of antimicrobial agents in food animal production, meat is frequently contaminated with antimicrobial-resistant Escherichia coli. Humans can be colonized with E. coli of animal origin, and because of resistance to commonly used antimicrobial agents, these bacteria may...... cause infections for which limited therapeutic options are available. This may lead to treatment failure and can have serious consequences for the patient. Furthermore, E. coli of animal origin may act as a donor of antimicrobial resistance genes for other pathogenic E. coli. Thus, the intensive use...

  3. DNA barcode reference library for Iberian butterflies enables a continental-scale preview of potential cryptic diversity

    Science.gov (United States)

    Dincă, Vlad; Montagud, Sergio; Talavera, Gerard; Hernández-Roldán, Juan; Munguira, Miguel L.; García-Barros, Enrique; Hebert, Paul D. N.; Vila, Roger

    2015-01-01

    How common are cryptic species - those overlooked because of their morphological similarity? Despite its wide-ranging implications for biology and conservation, the answer remains open to debate. Butterflies constitute the best-studied invertebrates, playing a similar role as birds do in providing models for vertebrate biology. An accurate assessment of cryptic diversity in this emblematic group requires meticulous case-by-case assessments, but a preview to highlight cases of particular interest will help to direct future studies. We present a survey of mitochondrial genetic diversity for the butterfly fauna of the Iberian Peninsula with unprecedented resolution (3502 DNA barcodes for all 228 species), creating a reliable system for DNA-based identification and for the detection of overlooked diversity. After compiling available data for European butterflies (5782 sequences, 299 species), we applied the Generalized Mixed Yule-Coalescent model to explore potential cryptic diversity at a continental scale. The results indicate that 27.7% of these species include from two to four evolutionary significant units (ESUs), suggesting that cryptic biodiversity may be higher than expected for one of the best-studied invertebrate groups and regions. The ESUs represent important units for conservation, models for studies of evolutionary and speciation processes, and sentinels for future research to unveil hidden diversity. PMID:26205828

  4. Clinical and genetic features of dyskeratosis congenita, cryptic dyskeratosis congenita, and Hoyeraal-Hreidarsson syndrome in Japan.

    Science.gov (United States)

    Yamaguchi, Hiroki; Sakaguchi, Hirotoshi; Yoshida, Kenichi; Yabe, Miharu; Yabe, Hiromasa; Okuno, Yusuke; Muramatsu, Hideki; Takahashi, Yoshiyuki; Yui, Shunsuke; Shiraishi, Yuichi; Chiba, Kenichi; Tanaka, Hiroko; Miyano, Satoru; Inokuchi, Koiti; Ito, Etsuro; Ogawa, Seishi; Kojima, Seiji

    2015-11-01

    Dyskeratosis congenita (DKC) is an inherited bone marrow failure (BMF) syndrome typified by reticulated skin pigmentation, nail dystrophy, and mucosal leukoplakia. Hoyeraal-Hreidarsson syndrome (HHS) is considered to be a severe form of DKC. Unconventional forms of DKC, which develop slowly in adulthood but without the physical anomalies characteristic of DKC (cryptic DKC), have been reported. Clinical and genetic features of DKC have been investigated in Caucasian, Black, and Hispanic populations, but not in Asian populations. The present study aimed to determine the clinical and genetic features of DKC, HHS, and cryptic DKC among Japanese patients. We analyzed 16 patients diagnosed with DKC, three patients with HHS, and 15 patients with cryptic DKC. We found that platelet count was significantly more depressed than neutrophil count or hemoglobin value in DKC patients, and identified DKC patients with large deletions in the telomerase reverse transcriptase and cryptic DKC patients with RTEL1 mutations on both alleles. This led to some patients previously considered to have unclassifiable BMF being diagnosed with cDKC through identification of new gene mutations. It thus seems important from a clinical viewpoint to re-examine the clinical characteristics, frequency of genetic mutations, and treatment efficacy in DKC, HHS, and cDKC.

  5. The activity of aminoglycoside antibiotics against Trypanosoma brucei.

    Science.gov (United States)

    Maina, N W; Kinyanjui, B; Onyango, J D; Auma, J E; Croj, S

    1998-01-01

    The trypanocidal activity of four aminoglycosides was determined against Trypanosoma brucei in vitro. The drug activity in descending order, was as follows; paromomycin kanamycin>gentamycin > neomycin. Paromomycin bad the highest activity and the concentration that inhibited 50% of trypanosome growth (IC50) was 11.4microM. The effect of paromomycin on the causative agents of the East African form of sleeping sickness - T.b. rhodesiense KETRI 265, 2285, 2545, 2562 and EATRO 110,112, 1152 was subsequently assessed. Variations sensitivities between the trypanosome populations were observed and IC50 values ranging from 13.01 to 43.06 microM recorded. However, when paromomycin was administered intraperitoneally (i.p) at 500 mg/kg, it was not effective in curing mice infected with T. b. rhodesienseKETRI 2545 the most drug-sensitive isolate in vitro. Lack of in vivo activity may be because the trypanosome is an extracellular parasite. The pharmacokinetics of paromomycin in the mouse model need to be determined.

  6. Population genetics and cryptic species

    International Nuclear Information System (INIS)

    McPheron, Bruce A.

    2000-01-01

    Does the definition of a species matter for pest management purposes? Taxonomists provide us with tools - usually morphological characters - to identify a group of organisms that we call a species. The implication of this identification is that all of the individuals that fit the provided description are members of the species in question. The taxonomists have considered the range of variation among individuals in defining the species, but this variation is often forgotten when we take the concept of species to the level of management. Just as there is morphological variation among individuals, there is also variation in practically any character we might imagine, which has implications for the short and long term success of our management tactics. The rich literature on insecticide resistance should be a constant reminder of the fact that the pressure on pest survival and reproduction applied by our management approaches frequently leads to evolutionary changes within the pest species. The degree of variation within a particular species is a defining characteristic of that species. This level of variability may have very important implications for successful management, so it is very important to measure variation and, whenever possible, the genetic basis of that variation, in a target species. Population genetic approaches can provide evidence of genetic structure (or lack thereof) among populations of a species. These types of data can be used to discuss the movement of pest populations on a local or global scale. In other cases, we may have a complex of species that share some, but not all, characteristics. Species complexes that share morphological characters (i.e., cannot be easily distinguished) but not biological characters are referred to as sibling or cryptic species

  7. Novel plasmids and resistance phenotypes in Yersinia pestis: unique plasmid inventory of strain Java 9 mediates high levels of arsenic resistance.

    Science.gov (United States)

    Eppinger, Mark; Radnedge, Lyndsay; Andersen, Gary; Vietri, Nicholas; Severson, Grant; Mou, Sherry; Ravel, Jacques; Worsham, Patricia L

    2012-01-01

    Growing evidence suggests that the plasmid repertoire of Yersinia pestis is not restricted to the three classical virulence plasmids. The Java 9 strain of Y. pestis is a biovar Orientalis isolate obtained from a rat in Indonesia. Although it lacks the Y. pestis-specific plasmid pMT, which encodes the F1 capsule, it retains virulence in mouse and non-human primate animal models. While comparing diverse Y. pestis strains using subtractive hybridization, we identified sequences in Java 9 that were homologous to a Y. enterocolitica strain carrying the transposon Tn2502, which is known to encode arsenic resistance. Here we demonstrate that Java 9 exhibits high levels of arsenic and arsenite resistance mediated by a novel promiscuous class II transposon, named Tn2503. Arsenic resistance was self-transmissible from Java 9 to other Y. pestis strains via conjugation. Genomic analysis of the atypical plasmid inventory of Java 9 identified pCD and pPCP plasmids of atypical size and two previously uncharacterized cryptic plasmids. Unlike the Tn2502-mediated arsenic resistance encoded on the Y. enterocolitica virulence plasmid; the resistance loci in Java 9 are found on all four indigenous plasmids, including the two novel cryptic plasmids. This unique mobilome introduces more than 105 genes into the species gene pool. The majority of these are encoded by the two entirely novel self-transmissible plasmids, which show partial homology and synteny to other enterics. In contrast to the reductive evolution in Y. pestis, this study underlines the major impact of a dynamic mobilome and lateral acquisition in the genome evolution of the plague bacterium.

  8. Novel plasmids and resistance phenotypes in Yersinia pestis: unique plasmid inventory of strain Java 9 mediates high levels of arsenic resistance.

    Directory of Open Access Journals (Sweden)

    Mark Eppinger

    Full Text Available Growing evidence suggests that the plasmid repertoire of Yersinia pestis is not restricted to the three classical virulence plasmids. The Java 9 strain of Y. pestis is a biovar Orientalis isolate obtained from a rat in Indonesia. Although it lacks the Y. pestis-specific plasmid pMT, which encodes the F1 capsule, it retains virulence in mouse and non-human primate animal models. While comparing diverse Y. pestis strains using subtractive hybridization, we identified sequences in Java 9 that were homologous to a Y. enterocolitica strain carrying the transposon Tn2502, which is known to encode arsenic resistance. Here we demonstrate that Java 9 exhibits high levels of arsenic and arsenite resistance mediated by a novel promiscuous class II transposon, named Tn2503. Arsenic resistance was self-transmissible from Java 9 to other Y. pestis strains via conjugation. Genomic analysis of the atypical plasmid inventory of Java 9 identified pCD and pPCP plasmids of atypical size and two previously uncharacterized cryptic plasmids. Unlike the Tn2502-mediated arsenic resistance encoded on the Y. enterocolitica virulence plasmid; the resistance loci in Java 9 are found on all four indigenous plasmids, including the two novel cryptic plasmids. This unique mobilome introduces more than 105 genes into the species gene pool. The majority of these are encoded by the two entirely novel self-transmissible plasmids, which show partial homology and synteny to other enterics. In contrast to the reductive evolution in Y. pestis, this study underlines the major impact of a dynamic mobilome and lateral acquisition in the genome evolution of the plague bacterium.

  9. Complete sequence of a cryptic virus from hemp (Cannabis sativa)

    Czech Academy of Sciences Publication Activity Database

    Ziegler, A.; Matoušek, Jaroslav; Steger, G.; Schubert, J.

    2012-01-01

    Roč. 157, č. 2 (2012), s. 383-385 ISSN 0304-8608 R&D Projects: GA ČR GCP501/10/J018 Institutional research plan: CEZ:AV0Z50510513 Keywords : Cannabis sativa * Partitivirus * cryptic virus Subject RIV: EE - Microbiology, Virology Impact factor: 2.030, year: 2012

  10. The diversity of antimicrobial resistance genes among staphylococci of animal origin.

    Science.gov (United States)

    Wendlandt, Sarah; Feßler, Andrea T; Monecke, Stefan; Ehricht, Ralf; Schwarz, Stefan; Kadlec, Kristina

    2013-08-01

    Staphylococci of animal origin harbor a wide variety of resistance genes. So far, more than 40 different resistance genes have been identified in staphylococci from animals. This includes genes that confer resistance to virtually all classes of antimicrobial agents approved for use in animals, such as penicillins, cephalosporins, tetracyclines, macrolides, lincosamides, phenicols, aminoglycosides, aminocyclitols, pleuromutilins, and diaminopyrimidines. The gene products of some of these resistance genes confer resistance to only specific members of a class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents. The resistance mechanisms specified by the resistance genes fall into three major categories: (i) enzymatic inactivation, (ii) active efflux, or (iii) protection/modification/replacement of the cellular target sites of the antimicrobial agents. Mobile genetic elements, in particular plasmids and transposons, play a major role as carriers of antimicrobial resistance genes in animal staphylococci. They facilitate the exchange of resistance genes with staphylococci of human origin but also with other Gram-positive bacteria. Copyright © 2013 Elsevier GmbH. All rights reserved.

  11. CD4+ T cells targeting dominant and cryptic epitopes from Bacillus anthracis Lethal Factor

    Directory of Open Access Journals (Sweden)

    Stephanie eAscough

    2016-01-01

    Full Text Available Anthrax is an endemic infection in many countries, particularly in the developing world. The causative agent, Bacillus anthracis, mediates disease through the secretion of binary exotoxins. Until recently, research into adaptive immunity targeting this bacterial pathogen has largely focused on the humoral response to these toxins. There is, however, growing recognition that cellular immune responses involving IFNγ producing CD4+ T cells also contribute significantly to a protective memory response. An established concept in adaptive immunity to infection is that during infection of host cells, new microbial epitopes may be revealed, leading to immune recognition of so called ‘cryptic’ or ‘subdominant’ epitopes. We analysed the response to both cryptic and immunodominant T cell epitopes derived from the toxin component lethal factor and presented by a range of HLA-DR alleles. Using IFNγ-ELISPOT assays we characterised epitopes that elicited a response following immunisation with synthetic peptide and the whole protein and tested their capacities to bind purified HLA-DR molecules in vitro. We found that DR1 transgenics demonstrated T cell responses to a greater number of domain III cryptic epitopes than other HLA-DR transgenics, and that this pattern was repeated with the immunodominant epitopes, a greater proportion of these epitopes induced a T cell response when presented within the context of the whole protein. Immunodominant epitopes LF457-476 and LF467-487 were found to induce a T cell response to the peptide, as well as to the whole native LF protein in DR1 and DR15, but not in DR4 trangenics. The analysis of Domain I revealed the presence of several unique cryptic epitopes all of which showed a strong to moderate relative binding affinity to HLA-DR4 molecules. However, none of the cryptic epitopes from either domain III or I displayed notably high binding affinities across all HLA-DR alleles assayed. These responses were

  12. Antibiotic resistance pattern in uropathogens

    Directory of Open Access Journals (Sweden)

    Gupta V

    2002-01-01

    Full Text Available Uropathogenic strains from inpatient and outpatient departments were studied from April 1997 to March 1999 for their susceptibility profiles. The various isolates were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter baumanii and Enterococcus faecalis. Antibiotic susceptibility pattern of these isolates revealed that for outpatients, first generation cephalosporins, nitrofurantoin, norfloxacin/ciprofloxacin were effective for treatment of urinary tract infection but for inpatients, parenteral therapy with newer aminoglycosides and third generation cephalosporins need to be advocated as the organisms for nosocomial UTI exhibit a high degree of drug resistance. Trimethoprim and sulphamethoxazole combination was not found to be effective for the treatment of urinary tract infections as all the uropathogens from inpatients and outpatients showed high degree of resistance to co-trimoxazole. Culture and sensitivity of the isolates from urine samples should be done as a routine before advocating the therapy.

  13. Mechanisms of antibiotic resistance in Staphylococcus aureus.

    Science.gov (United States)

    Pantosti, Annalisa; Sanchini, Andrea; Monaco, Monica

    2007-06-01

    Staphylococcus aureus can exemplify better than any other human pathogen the adaptive evolution of bacteria in the antibiotic era, as it has demonstrated a unique ability to quickly respond to each new antibiotic with the development of a resistance mechanism, starting with penicillin and methicillin, until the most recent, linezolid and daptomycin. Resistance mechanisms include enzymatic inactivation of the antibiotic (penicillinase and aminoglycoside-modification enzymes), alteration of the target with decreased affinity for the antibiotic (notable examples being penicillin-binding protein 2a of methicillin-resistant S. aureus and D-Ala-D-Lac of peptidoglycan precursors of vancomycin-resistant strains), trapping of the antibiotic (for vancomycin and possibly daptomycin) and efflux pumps (fluoroquinolones and tetracycline). Complex genetic arrays (staphylococcal chromosomal cassette mec elements or the vanA operon) have been acquired by S. aureus through horizontal gene transfer, while resistance to other antibiotics, including some of the most recent ones (e.g., fluoroquinolones, linezolid and daptomycin) have developed through spontaneous mutations and positive selection. Detection of the resistance mechanisms and their genetic basis is an important support to antibiotic susceptibility surveillance in S. aureus.

  14. Association between antimicrobial resistance in Escherichia coli isolates from food animals and blood stream isolates from humans in Europe: an ecological study.

    Science.gov (United States)

    Vieira, Antonio R; Collignon, Peter; Aarestrup, Frank M; McEwen, Scott A; Hendriksen, Rene S; Hald, Tine; Wegener, Henrik C

    2011-12-01

    In addition to medical antimicrobial usage, the use of antimicrobials in food animals contributes to the occurrence of resistance among some bacterial species isolated from infections in humans. Recently, several studies have indicated that a large proportion of Escherichia coli causing infections in humans, especially those resistant to antimicrobials, have an animal origin. We analyzed the correlation between the prevalence of antimicrobial resistance in E. coli isolates from blood stream infections in humans and in E. coli isolates from poultry, pigs, and cattle between 2005 and 2008 for 11 countries, using available surveillance data. We also assessed the correlation between human antimicrobial usage and the occurrence of resistance in E. coli isolates from blood stream infections. Strong and significant correlations between prevalences of resistance to ampicillin (r=0.94), aminoglycosides (r=0.72), third-generation cephalosporins (r=0.76), and fluoroquinolones (r=0.68) were observed for human and poultry E. coli isolates. Similar significant correlations were observed for ampicillin (r=0.91), aminoglycosides (r=0.73), and fluoroquinolone resistance (r=0.74) in pig and human isolates. In cattle isolates, only ampicillin resistance (r=0.72) was significantly correlated to human isolates. When usage of antimicrobials in humans was analyzed with antimicrobial resistance among human isolates, only correlations between fluoroquinolones (r=0.90) and third-generation cephalosporins (r=0.75) were significant. Resistance in E. coli isolates from food animals (especially poultry and pigs) was highly correlated with resistance in isolates from humans. This supports the hypothesis that a large proportion of resistant E. coli isolates causing blood stream infections in people may be derived from food sources.

  15. Streptococcus suis, an emerging drug-resistant animal and human pathogen

    Directory of Open Access Journals (Sweden)

    Claudio ePalmieri

    2011-11-01

    Full Text Available Streptococcus suis, a major porcine pathogen, has been receiving growing attention not only for its role in severe and increasingly reported infections in humans, but also for its involvement in drug resistance. Recent studies and the analysis of sequenced genomes have been providing important insights into the S. suis resistome, and have resulted in the identification of resistance determinants for tetracyclines, macrolides, aminoglycosides, chloramphenicol, antifolate drugs, streptothricin, and cadmium salts. Resistance gene-carrying genetic elements described so far include integrative and conjugative elements, transposons, genomic islands, phages, and chimeric elements. Some of these elements are similar to those reported in major streptococcal pathogens such as Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus agalactiae and share the same chromosomal insertion sites. The available information strongly suggests that S. suis is an important antibiotic resistance reservoir that can contribute to the spread of resistance genes to the above-mentioned streptococci. S. suis is thus a paradigmatic example of possible intersections between animal and human resistomes.

  16. Reflections on fourteen cryptic issues concerning the nature of statistical inference

    NARCIS (Netherlands)

    Kardaun, O.J.W.F.; Salomé, D.; Schaafsma, W; Steerneman, A.G.M.; Willems, J.C; Cox, D.R.

    The present paper provides the original formulation and a joint response of a group of statistically trained scientists to fourteen cryptic issues for discussion, which were handed out to the public by Professor Dr. D.R. Cox after his Bernoulli Lecture 1997 at Groningen University.

  17. Antibiotic resistance in Escherichia coli strains isolated from Antarctic bird feces, water from inside a wastewater treatment plant, and seawater samples collected in the Antarctic Treaty area

    Science.gov (United States)

    Rabbia, Virginia; Bello-Toledo, Helia; Jiménez, Sebastián; Quezada, Mario; Domínguez, Mariana; Vergara, Luis; Gómez-Fuentes, Claudio; Calisto-Ulloa, Nancy; González-Acuña, Daniel; López, Juana; González-Rocha, Gerardo

    2016-06-01

    Antibiotic resistance is a problem of global concern and is frequently associated with human activity. Studying antibiotic resistance in bacteria isolated from pristine environments, such as Antarctica, extends our understanding of these fragile ecosystems. Escherichia coli strains, important fecal indicator bacteria, were isolated on the Fildes Peninsula (which has the strongest human influence in Antarctica), from seawater, bird droppings, and water samples from inside a local wastewater treatment plant. The strains were subjected to molecular typing with pulsed-field gel electrophoresis to determine their genetic relationships, and tested for antibiotic susceptibility with disk diffusion tests for several antibiotic families: β-lactams, quinolones, aminoglycosides, tetracyclines, phenicols, and trimethoprim-sulfonamide. The highest E. coli count in seawater samples was 2400 cfu/100 mL. Only strains isolated from seawater and the wastewater treatment plant showed any genetic relatedness between groups. Strains of both these groups were resistant to β-lactams, aminoglycosides, tetracycline, and trimethoprim-sulfonamide.In contrast, strains from bird feces were susceptible to all the antibiotics tested. We conclude that naturally occurring antibiotic resistance in E. coli strains isolated from Antarctic bird feces is rare and the bacterial antibiotic resistance found in seawater is probably associated with discharged treated wastewater originating from Fildes Peninsula treatment plants.

  18. Metagenomic profiles of antibiotic resistance genes (ARGs) between human impacted estuary and deep ocean sediments.

    Science.gov (United States)

    Chen, Baowei; Yang, Ying; Liang, Ximei; Yu, Ke; Zhang, Tong; Li, Xiangdong

    2013-11-19

    Knowledge of the origins and dissemination of antibiotic resistance genes (ARGs) is essential for understanding modern resistomes in the environment. The mechanisms of the dissemination of ARGs can be revealed through comparative studies on the metagenomic profiling of ARGs between relatively pristine and human-impacted environments. The deep ocean bed of the South China Sea (SCS) is considered to be largely devoid of anthropogenic impacts, while the Pearl River Estuary (PRE) in south China has been highly impacted by intensive human activities. Commonly used antibiotics (sulfamethazine, norfloxacin, ofloxacin, tetracycline, and erythromycin) have been detected through chemical analysis in the PRE sediments, but not in the SCS sediments. In the relatively pristine SCS sediments, the most prevalent and abundant ARGs are those related to resistance to macrolides and polypeptides, with efflux pumps as the predominant mechanism. In the contaminated PRE sediments, the typical ARG profiles suggest a prevailing resistance to antibiotics commonly used in human health and animal farming (including sulfonamides, fluoroquinolones, and aminoglycosides), and higher diversity in both genotype and resistance mechanism than those in the SCS. In particular, antibiotic inactivation significantly contributed to the resistance to aminoglycosides, β-lactams, and macrolides observed in the PRE sediments. There was a significant correlation in the levels of abundance of ARGs and those of mobile genetic elements (including integrons and plasmids), which serve as carriers in the dissemination of ARGs in the aquatic environment. The metagenomic results from the current study support the view that ARGs naturally originate in pristine environments, while human activities accelerate the dissemination of ARGs so that microbes would be able to tolerate selective environmental stress in response to anthropogenic impacts.

  19. Ionizing radiation modulates the exposure of the HUIV26 cryptic epitope within collagen type IV during angiogenesis

    International Nuclear Information System (INIS)

    Brooks, Peter C.; Roth, Jennifer M.; Lymberis, Stella C.; DeWyngaert, Keith; Broek, Daniel; Formenti, Silvia C.

    2002-01-01

    Purpose: The majority of the research on the biologic effects of ionizing radiation has focused on the impact of radiation on cells in terms of gene expression, DNA damage, and cytotoxicity. In comparison, little information is available concerning the direct effects of radiation on the extracellular microenvironment, specifically the extracellular matrix and its main component, collagen. We have developed a series of monoclonal antibodies that bind to cryptic epitopes of collagen Type IV that are differentially exposed during matrix remodeling and are key mediators of angiogenesis. We have hypothesized that ionizing radiation might affect the process of angiogenesis through a direct effect on the extracellular matrix and specifically on collagen Type IV. Methods and Materials: Angiogenesis was induced in a chick chorioallantoic membrane (CAM) model; 24 h later, a single-dose treatment with ionizing radiation (0.5, 5, and 20 cGy) was administered. Angiogenesis was assessed, and the exposure of two cryptic regulatory epitopes within collagen Type IV (HUI77 and HUIV26) was studied in vitro by solid-phase ELISA and in vivo by immunofluorescence staining. Results: A dose-dependent reduction of angiogenesis with maximum inhibition (85%-90%) occurring at 20 cGy was demonstrated in the CAM model. Exposure of the cryptic HUIV26 site, an angiogenesis control element, was inhibited both in vitro and in vivo by the same radiation dose, whereas little if any change was observed for the HUI77 cryptic epitope. Conclusions: A dose-dependent alteration of the functional exposure of the HUIV26 cryptic epitope is induced by radiation in vitro and in the CAM model in vivo. This radiation-induced change in protein structure and function may contribute to the inhibitory effects of ionizing radiation on new blood vessel growth and warrants further studies in other models

  20. Determination of stability constants of aminoglycoside antibiotics with their metal complexes

    Science.gov (United States)

    Tiwow, Vanny M. A.

    2014-03-01

    One group of aminoglycoside antibiotics contains aminosugars. The aminosugar neomycin B with its derivate product neamine (2-Deoxy-4-0-(2,6-diamino-2,6-dideoxy-α-D-glucopyranosyl)-D-Streptamine) was identified as a free ligands and metal complexes. In particular, the stability constants of metal complexes by potentiometric titration techniques were investigated. Our previous study had determined the acid dissociation constants of these aminosugars with few metal complexes in fair depth. In this work, the complexation of two pyridine-containing amino alcohols and an amino sugar (neamine) have been measured potentiometrically. For instance, the stability constant of copper(II) complexation were determine and the model system generated an excellent fit. Stability constants with several metals have been determined and will be reported.

  1. Clinical and molecular analysis of a four-generation Chinese family with aminoglycoside-induced and nonsyndromic hearing loss associated with the mitochondrial 12S rRNA C1494T mutation

    International Nuclear Information System (INIS)

    Wang Qiuju; Li Qingzhong; Han Dongyi; Zhao Yali; Zhao Lidong; Qian Yaping; Yuan Hu; Li Ronghua; Zhai Suoqiang; Young Wieyen; Guan Minxin

    2006-01-01

    We report here the clinical, genetic, and molecular characterization of a four-generation Chinese family with aminoglycoside-induced and nonsyndromic hearing loss. Five of nine matrilineal relatives had aminoglycoside-induced hearing loss. These matrilineal relatives exhibited variable severity and audiometric configuration of hearing impairment, despite sharing some common features: being bilateral and having sensorineural hearing impairment. Sequence analysis of mitochondrial DNA (mtDNA) in the pedigree identified 16 variants and the homoplasmic 12S rRNA C1494T mutation, which was associated with hearing loss in the other large Chinese family. In fact, the occurrence of the C1494T mutation in these genetically unrelated pedigrees affected by hearing impairment strongly indicated that this mutation is involved in the pathogenesis of aminoglycoside-induced and nonsyndromic hearing loss. However, incomplete penetrance of hearing loss indicated that the C1494T mutation itself is not sufficient to produce a clinical phenotype but requires the involvement of modifier factors for the phenotypic expression. Those mtDNA variants, showing no evolutional conservation, may not have a potential modifying role in the pathogenesis of the C1494T mutation. However, nuclear background seems to contribute to the phenotypic variability of matrilineal relatives in this family. Furthermore, aminoglycosides modulate the expressivity and penetrance of deafness associated with the C1494T mutation in this family

  2. Transcriptome Profiling of Antimicrobial Resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Khaledi, Ariane; Schniederjans, Monika; Pohl, Sarah; Rainer, Roman; Bodenhofer, Ulrich; Xia, Boyang; Klawonn, Frank; Bruchmann, Sebastian; Preusse, Matthias; Eckweiler, Denitsa; Dötsch, Andreas; Häussler, Susanne

    2016-08-01

    Emerging resistance to antimicrobials and the lack of new antibiotic drug candidates underscore the need for optimization of current diagnostics and therapies to diminish the evolution and spread of multidrug resistance. As the antibiotic resistance status of a bacterial pathogen is defined by its genome, resistance profiling by applying next-generation sequencing (NGS) technologies may in the future accomplish pathogen identification, prompt initiation of targeted individualized treatment, and the implementation of optimized infection control measures. In this study, qualitative RNA sequencing was used to identify key genetic determinants of antibiotic resistance in 135 clinical Pseudomonas aeruginosa isolates from diverse geographic and infection site origins. By applying transcriptome-wide association studies, adaptive variations associated with resistance to the antibiotic classes fluoroquinolones, aminoglycosides, and β-lactams were identified. Besides potential novel biomarkers with a direct correlation to resistance, global patterns of phenotype-associated gene expression and sequence variations were identified by predictive machine learning approaches. Our research serves to establish genotype-based molecular diagnostic tools for the identification of the current resistance profiles of bacterial pathogens and paves the way for faster diagnostics for more efficient, targeted treatment strategies to also mitigate the future potential for resistance evolution. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  3. Ecological Variation in Response to Mass-Flowering Oilseed Rape and Surrounding Landscape Composition by Members of a Cryptic Bumblebee Complex.

    Directory of Open Access Journals (Sweden)

    Dara A Stanley

    Full Text Available The Bombus sensu stricto species complex is a widespread group of cryptic bumblebee species which are important pollinators of many crops and wild plants. These cryptic species have, until now, largely been grouped together in ecological studies, and so little is known about their individual colony densities, foraging ranges or habitat requirements, which can be influenced by land use at a landscape scale. We used mass-flowering oilseed rape fields as locations to sample bees of this complex, as well as the second most common visitor to oilseed rape B. lapidarius, and molecular RFLP methods to distinguish between the cryptic species. We then used microsatellite genotyping to identify sisters and estimate colony densities, and related both proportions of cryptic species and their colony densities to the composition of the landscape surrounding the fields. We found B. lucorum was the most common member of the complex present in oilseed rape followed by B. terrestris. B. cryptarum was also present in all but one site, with higher proportions found in the east of the study area. High numbers of bumblebee colonies were estimated to be using oilseed rape fields as a forage resource, with B. terrestris colony numbers higher than previous estimates from non-mass-flowering fields. We also found that the cryptic species responded differently to surrounding landscape composition: both relative proportions of B. cryptarum in samples and colony densities of B. lucorum were negatively associated with the amount of arable land in the landscape, while proportions and colony densities of other species did not respond to landscape variables at the scale measured. This suggests that the cryptic species have different ecological requirements (which may be scale-dependent and that oilseed rape can be an important forage resource for many colonies of bumblebees. Given this, we recommend sustainable management of this crop to benefit bumblebees.

  4. Biofilm architecture of Phanerozoic cryptic carbonate marine veneers

    Science.gov (United States)

    Riding, Robert

    2002-01-01

    Thin (mushrooms, and plumes. All can be interpreted as characteristics of attached bacterial communities, i.e., aggregates as microcolonies, originally embedded in a matrix of extracellular polymeric substances; channels as water conduits and/or uncolonized nutrient-poor spaces; external protuberances as localized growths; and plumes as surface streamers. Cryptic habitat favored pristine biofilm preservation by precluding disturbance and overgrowth, and suggests aphotic and anoxic conditions. These examples provide diagnostic morphologic criteria for wider recognition of biofilm in Phanerozoic and older carbonates.

  5. Balancing selection maintains cryptic colour morphs.

    Science.gov (United States)

    Wellenreuther, Maren

    2017-11-01

    Animals display incredibly diverse colour patterns, a testament to evolution's endless innovation in shaping life. In many species, the interplay between males and females in the pursuit of mates has driven the evolution of a myriad of colour forms, from the flashy peacock tail feathers to the tiniest colour markings in damselflies. In others, colour provides crypsis by allowing to blend into the background and to escape the eyes of predators. While the obvious benefits of this dazzling diversity for reproduction and survival seem straightforward, its maintenance is not. Theory predicts that genetic drift and various forms of selection reduce variation over time, making the persistence of colour variants over generations a puzzle. In this issue of Molecular Ecology, Lindtke et al. () study the cryptic colour morphs of Timema cristinae walking sticks to shed light on the genetic architecture and mechanisms that allow colour polymorphism maintenance over long timescales. By combining genome-wide data with phenotyping information from natural populations, they were able to map the green and melanistic colour to one genomic region with highly reduced effective recombination rate between two main chromosomal variants, consistent with an inversion polymorphism. These two main chromosomal variants showed geographically widespread heterozygote excess, and genomic signatures consistent with long-term balancing selection. A younger chromosomal variant was detected for the third morph, the green-striped colour morphs, in the same genomic regions as the melanistic and the green-unstriped morphs. Together, these results suggest that the genetic architecture of cryptic T. cristinae morphs is caused by nonrecombining genomic blocks that have been maintained over extended time periods by balancing selection making this study one of the few available empirical examples documenting that balancing selection of various forms may play an important role in maintaining adaptive genetic

  6. Molecular Basis of Resistance to Selected Antimicrobial Agents in the Emerging Zoonotic Pathogen Streptococcus suis.

    Science.gov (United States)

    Gurung, Mamata; Tamang, Migma Dorji; Moon, Dong Chan; Kim, Su-Ran; Jeong, Jin-Ha; Jang, Geum-Chan; Jung, Suk-Chan; Park, Yong-Ho; Lim, Suk-Kyung

    2015-07-01

    Characterization of 227 Streptococcus suis strains isolated from pigs during 2010 to 2013 showed high levels of resistance to clindamycin (95.6%), tilmicosin (94.7%), tylosin (93.8%), oxytetracycline (89.4%), chlortetracycline (86.8%), tiamulin (72.7%), neomycin (70.0%), enrofloxacin (56.4%), penicillin (56.4%), ceftiofur (55.9%), and gentamicin (55.1%). Resistance to tetracyclines, macrolides, aminoglycosides, and fluoroquinolone was attributed to the tet gene, erm(B), erm(C), mph(C), and mef(A) and/or mef(E) genes, aph(3')-IIIa and aac(6')-Ie-aph(2″)-Ia genes, and single point mutations in the quinolone resistance-determining region of ParC and GyrA, respectively. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  7. Infective endocarditis due to Enterobacter cloacae resistant to third- and fourth-generation cephalosporins.

    Science.gov (United States)

    Yoshino, Yusuke; Okugawa, Shu; Kimura, Satoshi; Makita, Eiko; Seo, Kazunori; Koga, Ichiro; Matsunaga, Naohisa; Kitazawa, Takatoshi; Ota, Yasuo

    2015-04-01

    We report the case of using a long-term combination of meropenem and amikacin to treat infective endocarditis caused by Enterobacter cloacae resistant to third- and fourth-generation cephalosporins. Multi-drug resistant Gram-negative bacilli, such as the E. cloacae in our study, may become possible pathogens of infective endocarditis. Our experience with this case indicates that long-term use of a combination of β-lactam and aminoglycosides might represent a suitable management option for future infective endocarditis cases due to non-Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella spp. (HACEK group) Gram-negative bacilli such as ours. Copyright © 2012. Published by Elsevier B.V.

  8. Widespread prevalence of cryptic Symbiodinium D in the key Caribbean reef builder, Orbicella annularis

    Science.gov (United States)

    Kennedy, Emma V.; Foster, Nicola L.; Mumby, Peter J.; Stevens, Jamie R.

    2015-06-01

    Symbiodinium D, a relatively rare clade of algal endosymbiont with a global distribution, has attracted interest as some of its sub-cladal types induce increased thermal tolerance and associated trade-offs, including reduced growth rate in its coral hosts. Members of Symbiodinium D are increasingly reported to comprise low-abundance `cryptic' (30 % of corals per site found to harbour the symbiont. When the same samples were analysed using the conventional screening technique, denaturing gradient gel electrophoresis, Symbiodinium D1 was only detected in 12 populations and appeared to be hosted by agreement with other reported low prevalence/absences in O. annularis). Cryptic Symbiodinium D1 showed a mainly uniform distribution across the wider Caribbean region, although significantly more Mesoamerican Barrier Reef corals hosted cryptic Symbiodinium D1 than might be expected by chance, possibly as a consequence of intense warming in the region in 1998. Widespread prevalence of thermally tolerant Symbiodinium in O. annularis may potentially reflect a capacity for the coral to temporarily respond to warming events through symbiont shuffling. However, association with reduced coral calcification means that the ubiquitous nature of Symbiodinium D1 in O. annularis populations is unlikely to prevent long-term declines in reef health, at a time when maintaining reef growth is vital to sustain reef ecosystem function.

  9. Diversity and Distribution of Cryptic Species of the Bemisia tabaci (Hemiptera: Aleyrodidae) complex in Pakistan.

    Science.gov (United States)

    Masood, Mariyam; Amin, Imran; Hassan, Ishtiaq; Mansoor, Shahid; Brown, Judith K; Briddon, Rob W

    2017-12-05

    Bemisia tabaci (Gennadius; Hempitera: Aleyrodidae) is considered to be a cryptic (sibling) species complex, the members of which exhibit morphological invariability while being genetically and behaviorally distinct. Members of the complex are agricultural pests that cause direct damage by feeding on plants, and indirectly by transmitting viruses that cause diseases leading to reduced crop yield and quality. In Pakistan, cotton leaf curl disease, caused by multiple begomovirus species, is the most economically important viral disease of cotton. In the study outlined here, the diversity and geographic distribution of B. tabaci cryptic species was investigated by analyzing a taxonomically informative fragment of the mitochondrial cytochrome c oxidase 1 gene (mtCOI-3'). The mtCOI-3' sequence was determined for 285 adult whiteflies and found to represent six cryptic species, the most numerous being Asia II-1 and Middle East Asia Minor 1 (MEAM-1), the later also referred to as the B-biotype, which was previously thought to be confined to Sindh province but herein, was also found to be present in the Punjab province. The endemic Asia I was restricted to Sindh province, while an individual in the Asia II-8 was identified in Pakistan for the first time. Also for the first time, samples were collected from northwestern Pakistan and Asia II-1 was identified. Results indicate that in Pakistan the overall diversity of B. tabaci cryptic species is high and, based on comparisons with findings from previous studies, the distribution is dynamic. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. The taxonomy of the Caloplaca citrina group (Teloschistaceae) in the Black Sea region; with contributions to the cryptic species concept in lichenology

    DEFF Research Database (Denmark)

    Vondrák, Jan; RÍHA, Pavel; ARUP, Ulf

    2009-01-01

    . The variability and taxonomic importance of particular features are discussed. No significant differences in secondary chemistry were observed among the species. Many examples of convergence and some semi-cryptic species were revealed by molecular data. The term ‘semi-cryptic species' is introduced here...

  11. Widespread acquisition of antimicrobial resistance among Campylobacter isolates from UK retail poultry and evidence for clonal expansion of resistant lineages.

    Science.gov (United States)

    Wimalarathna, Helen M L; Richardson, Judith F; Lawson, Andy J; Elson, Richard; Meldrum, Richard; Little, Christine L; Maiden, Martin C J; McCarthy, Noel D; Sheppard, Samuel K

    2013-07-15

    Antimicrobial resistance is increasing among clinical Campylobacter cases and is common among isolates from other sources, specifically retail poultry - a major source of human infection. In this study the antimicrobial susceptibility of isolates from a UK-wide survey of Campylobacter in retail poultry in 2001 and 2004-5 was investigated. The occurrence of phenotypes resistant to tetracycline, quinolones (ciprofloxacin and naladixic acid), erythromycin, chloramphenicol and aminoglycosides was quantified. This was compared with a phylogeny for these isolates based upon Multi Locus Sequence Typing (MLST) to investigate the pattern of antimicrobial resistance acquisition. Antimicrobial resistance was present in all lineage clusters, but statistical testing showed a non-random distribution. Erythromycin resistance was associated with Campylobacter coli. For all antimicrobials tested, resistant isolates were distributed among relatively distant lineages indicative of widespread acquisition. There was also evidence of clustering of resistance phenotypes within lineages; indicative of local expansion of resistant strains. These results are consistent with the widespread acquisition of antimicrobial resistance among chicken associated Campylobacter isolates, either through mutation or horizontal gene transfer, and the expansion of these lineages as a proportion of the population. As Campylobacter are not known to multiply outside of the host and long-term carriage in humans is extremely infrequent in industrialized countries, the most likely location for the proliferation of resistant lineages is in farmed chickens.

  12. A Simple Model for Inducing Optimal Increase of SDF-1 with Aminoglycoside Ototoxicity

    Directory of Open Access Journals (Sweden)

    Hyun Mi Ju

    2017-01-01

    Full Text Available Objectives. As a homing factor of stem cell, stromal derived factor-1 (SDF-1 is important for the regenerative research in ototoxicity. Mice models with aminoglycoside ototoxicity have been widely used to study the regeneration capacity of MSCs in repair of cochlear injury. We developed a mouse model with maximal increase in SDF-1 levels in the inner ear, according to the “one-shot” doses of kanamycin and furosemide. Methods. C57BL/6 mice had kanamycin (420, 550, and 600 mg/kg dissolved in PBS, followed by an intraperitoneal injection of furosemide (130 mg/kg. The injuries of inner ear were measured with hearing thresholds, histology, and outer hair cell counts at 0, 3, 5, 7, 10, and 14 days before the sacrifice. The levels of SDF-1 in the inner ear were tested by real-time RT-PCR and immunohistochemistry. Results. There were a significant reduction in hearing thresholds and a maximal increase of SDF-1 levels in the furosemide 130 mg/kg + kanamycin 550 mg/kg group, but severe hearing deterioration over time was observed in the furosemide 130 mg/kg + kanamycin 600 mg/kg group and four mice were dead. SDF-1 was detected mostly in the stria vascularis and organ of Corti showing the highest increase in expression. Conclusion. We observed optimal induction of the stem cell homing factor in the newly generated aminoglycoside-induced ototoxicity mouse model using a “one-shot” protocol. This study regarding high SDF-1 levels in our mouse model of ototoxicity would play a major role in the development of therapeutic agents using MSC homing.

  13. Acoustic divergence in the communication of cryptic species of nocturnal primates (Microcebus ssp.

    Directory of Open Access Journals (Sweden)

    Zimmermann Elke

    2008-05-01

    Full Text Available Abstract Background A central question in evolutionary biology is how cryptic species maintain species cohesiveness in an area of sympatry. The coexistence of sympatrically living cryptic species requires the evolution of species-specific signalling and recognition systems. In nocturnal, dispersed living species, specific vocalisations have been suggested to act as an ideal premating isolation mechanism. We studied the structure and perception of male advertisement calls of three nocturnal, dispersed living mouse lemur species, the grey mouse lemur (Microcebus murinus, the golden brown mouse lemur (M. ravelobensis and the Goodman's mouse lemur (M. lehilahytsara. The first two species occur sympatrically, the latter lives allopatrically to them. Results A multi-parameter sound analysis revealed prominent differences in the frequency contour and in the duration of advertisement calls. To test whether mouse lemurs respond specifically to calls of the different species, we conducted a playback experiment with M. murinus from the field using advertisement calls and alarm whistle calls of all three species. Individuals responded significantly stronger to conspecific than to heterospecific advertisement calls but there were no differences in response behaviour towards statistically similar whistle calls of the three species. Furthermore, sympatric calls evoked weaker interest than allopatric advertisement calls. Conclusion Our results provide the first evidence for a specific relevance of social calls for speciation in cryptic primates. They furthermore support that specific differences in signalling and recognition systems represent an efficient premating isolation mechanism contributing to species cohesiveness in sympatrically living species.

  14. Cryptic species of sharp-nosed reed frogs in the Hyperolius nasutus ...

    African Journals Online (AJOL)

    The sharp-nosed reed frog is widespread in Africa. Although currently recognized as one species, suggestions have been made that more than one species might exist. We analysed 237 calls of 69 males from 19 localities in the western to southern parts of Africa. Calls fall into three groups, which we recognize as cryptic ...

  15. Investigation into complexing of phthalexone S with praseodymium ions and some aminoglycoside antibiotics

    International Nuclear Information System (INIS)

    Alykov, N.M.

    1981-01-01

    Complex formation of phthalexone S (Phth) with praseodymium ion and some aminoglycoside antibiotics (Ab) in aqueous ethanol solutions (1:1) has been examined photometrically at 619 mm. It has been shown that compounds with the ratios of Ab:Pr:Phth=1:2:8, 1:1:4, 1:1:3 are formed depending on the number of amino groups and structure of the antibiotics. The molar absorptivities and solubility products for the complexes have been calculated. The complex formation scheme is given. A procedure has been developed of determining 0.01-10 μg of antibiotics in 1 ml of a biological material with a relative error of less than 10% [ru

  16. Biology of Acinetobacter baumannii: Pathogenesis, Antibiotic Resistance Mechanisms, and Prospective Treatment Options

    Science.gov (United States)

    Lee, Chang-Ro; Lee, Jung Hun; Park, Moonhee; Park, Kwang Seung; Bae, Il Kwon; Kim, Young Bae; Cha, Chang-Jun; Jeong, Byeong Chul; Lee, Sang Hee

    2017-01-01

    Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A. baumannii pathogenesis, including porins, capsular polysaccharides, lipopolysaccharides, phospholipases, outer membrane vesicles, metal acquisition systems, and protein secretion systems. Mechanisms of antibiotic resistance of this organism, including acquirement of β-lactamases, up-regulation of multidrug efflux pumps, modification of aminoglycosides, permeability defects, and alteration of target sites, are also discussed. Lastly, novel prospective treatment options for infections caused by multi-drug resistant A. baumannii are summarized. PMID:28348979

  17. Cryptic Transcription and Early Termination in the Control of Gene Expression

    Directory of Open Access Journals (Sweden)

    Jessie Colin

    2011-01-01

    Full Text Available Recent studies on yeast transcriptome have revealed the presence of a large set of RNA polymerase II transcripts mapping to intergenic and antisense regions or overlapping canonical genes. Most of these ncRNAs (ncRNAs are subject to termination by the Nrd1-dependent pathway and rapid degradation by the nuclear exosome and have been dubbed cryptic unstable transcripts (CUTs. CUTs are often considered as by-products of transcriptional noise, but in an increasing number of cases they play a central role in the control of gene expression. Regulatory mechanisms involving expression of a CUT are diverse and include attenuation, transcriptional interference, and alternative transcription start site choice. This review focuses on the impact of cryptic transcription on gene expression, describes the role of the Nrd1-complex as the main actor in preventing nonfunctional and potentially harmful transcription, and details a few systems where expression of a CUT has an essential regulatory function. We also summarize the most recent studies concerning other types of ncRNAs and their possible role in regulation.

  18. Cyanomargarita gen. nov. (Nostocales, Cyanobacteria): convergent evolution resulting in a cryptic genus

    Czech Academy of Sciences Publication Activity Database

    Shalygin, S.; Shalygina, R.; Johansen, J. R.; Pietrasiak, N.; Gómez, E. B.; Bohunická, M.; Mareš, Jan; Sheil, C.A.

    2017-01-01

    Roč. 53, č. 4 (2017), s. 762-777 ISSN 0022-3646 Institutional support: RVO:60077344 Keywords : 16S rRNA gene phylogeny * 16S-23S ITS * cryptic genus * Cyanobacteria * Cyanomargarita Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.608, year: 2016

  19. Temperature effects on gametophyte life-history traits and geographic distribution of two cryptic kelp species.

    Directory of Open Access Journals (Sweden)

    L Valeria Oppliger

    Full Text Available A major determinant of the geographic distribution of a species is expected to be its physiological response to changing abiotic variables over its range. The range of a species often corresponds to the geographic extent of temperature regimes the organism can physiologically tolerate. Many species have very distinct life history stages that may exhibit different responses to environmental factors. In this study we emphasized the critical role of the haploid microscopic stage (gametophyte of the life cycle to explain the difference of edge distribution of two related kelp species. Lessonia nigrescens was recently identified as two cryptic species occurring in parapatry along the Chilean coast: one located north and the other south of a biogeographic boundary at latitude 29-30°S. Six life history traits from microscopic stages were identified and estimated under five treatments of temperature in eight locations distributed along the Chilean coast in order to (1 estimate the role of temperature in the present distribution of the two cryptic L. nigrescens species, (2 compare marginal populations to central populations of the two cryptic species. In addition, we created a periodic matrix model to estimate the population growth rate (λ at the five temperature treatments. Differential tolerance to temperature was demonstrated between the two species, with the gametophytes of the Northern species being more tolerant to higher temperatures than gametophytes from the south. Second, the two species exhibited different life history strategies with a shorter haploid phase in the Northern species contrasted with considerable vegetative growth in the Southern species haploid stage. These results provide strong ecological evidence for the differentiation process of the two cryptic species and show local adaptation of the life cycle at the range limits of the distribution. Ecological and evolutionary implications of these findings are discussed.

  20. Ab initio prediction of mutation-induced cryptic splice-site activation and exon skipping

    Czech Academy of Sciences Publication Activity Database

    Divina, Petr; Kvitkovicova, Andrea; Buratti, E.; Vorechovsky, I.

    2009-01-01

    Roč. 17, č. 6 (2009), s. 759-765 ISSN 1018-4813 Institutional research plan: CEZ:AV0Z50520514 Keywords : mutation * cryptic splice site * exon skipping Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.564, year: 2009

  1. Field identification of the cryptic vespertilionid bats, Myotis lucifugus and M. yumanensis

    Science.gov (United States)

    Theodore J. Weller; Shonene A. Scott; Thomas J. Rodhouse; Patricia C. Ormsbee; Jan M. Zinck

    2007-01-01

    Recent advances in molecular techniques have provided new tools for confirming species identities, however they can be expensive and results are not immediately available. Myotis lucificugus and M. yumanensis are morphologically cryptic species of bats sympatric in western North America that can be difficult to distinguish in the...

  2. Is Eucalyptus Cryptically Self-incompatible?

    Science.gov (United States)

    Horsley, Tasmien N; Johnson, Steven D

    2007-12-01

    The probability that seeds will be fertilized from self- versus cross-pollen depends strongly on whether plants have self-incompatibility systems, and how these systems influence the fate of pollen tubes. In this study of breeding systems in Eucalyptus urophylla and Eucalyptus grandis, epifluorescence microscopy was used to study pollen tube growth in styles following self- and cross-pollinations. Pollen tubes from self-pollen took significantly longer than those from cross-pollen to grow to the base of the style in both E. urophylla (120 h vs. 96 h) and E. grandis (96 h vs. 72 h). In addition, both species exhibited reduced seed yields following self-pollination compared with cross-pollination. The present observations suggest that, in addition to a late-acting self-incompatibility barrier, cryptic self-incompatibility could be a mechanism responsible for the preferential out-crossing system in these two eucalypt species.

  3. Detection of Specific Solvent Rearrangement Regions of an Enzyme: NMR and ITC Studies with Aminoglycoside Phosphotransferase(3 )-IIIa

    International Nuclear Information System (INIS)

    Ozen, C.; Norris, Adrianne; Land, Miriam Louise; Tjioe, Elina; Serpersu, Engin H

    2008-01-01

    This work describes differential effects of solvent in complexes of the aminoglycoside phosphotransferase(3 and cent;)-IIIa (APH) with different aminoglycosides and the detection of change in solvent structure at specific sites away from substrates. Binding of kanamycins to APH occurs with a larger negative and cent;H in H2O relative to D2O ( and cent; and cent;H(H2O-D2O) < 0), while the reverse is true for neomycins. Unusually large negative and cent;Cp values were observed for binding of aminoglycosides to APH. and cent;Cp for the APHneomycin complex was -1.6 kcal and acirc;mol-1 and acirc;deg-1. A break at 30 C was observed in the APH-kanamycin complex yielding and cent;Cp values of -0.7 kcal and acirc;mol-1 and acirc;deg-1 and -3.8 kcal and acirc;mol-1 and acirc;deg-1 below and above 30 C, respectively. Neither the change in accessible surface area ( and cent;ASA) nor contributions from heats of ionization were sufficient to explain the large negative and cent;Cp values. Most significantly, 15N-1H HSQC experiments showed that temperature-dependent shifts of the backbone amide protons of Leu 88, Ser 91, Cys 98, and Leu143 revealed a break at 30 C only in the APH-kanamycin complex in spectra collected between 21 C and 38 C. These amino acids represent solVent reorganization sites that experience a change in solvent structure in their immediate environment as structurally different ligands bind to the enzyme. These residues were away from the substrate binding site and distributed in three hydrophobic patches in APH. Overall, our results show that a large number of factors affect and cent;Cp and binding of structurally different ligand groups cause different solvent structure in the active site as well as differentially affecting specific sites away from the ligand binding site

  4. Cyanomargarita gen. nov. (Nostocales, Cyanobacteria): convergent evolution resulting in a cryptic genus

    Czech Academy of Sciences Publication Activity Database

    Shalygin, S.; Shalygina, R.; Johansen, J. R.; Pietrasiak, N.; Gómez, E. B.; Bohunická, Markéta; Mareš, Jan; Sheil, C.A.

    2017-01-01

    Roč. 53, č. 4 (2017), s. 762-777 ISSN 0022-3646 R&D Projects: GA ČR(CZ) GA15-11912S Institutional support: RVO:67985939 Keywords : 16S rRNA gene * cryptic genus * Cyanomargarita Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.608, year: 2016

  5. Activation of dormant secondary metabolite production by introducing neomycin resistance into the deep-sea fungus, Aspergillus versicolor ZBY-3.

    Science.gov (United States)

    Dong, Yuan; Cui, Cheng-Bin; Li, Chang-Wei; Hua, Wei; Wu, Chang-Jing; Zhu, Tian-Jiao; Gu, Qian-Qun

    2014-07-29

    A new ultrasound-mediated approach has been developed to introduce neomycin-resistance to activate silent pathways for secondary metabolite production in a bio-inactive, deep-sea fungus, Aspergillus versicolor ZBY-3. Upon treatment of the ZBY-3 spores with a high concentration of neomycin by proper ultrasound irradiation, a total of 30 mutants were obtained by single colony isolation. The acquired resistance of the mutants to neomycin was confirmed by a resistance test. In contrast to the ZBY-3 strain, the EtOAc extracts of 22 of the 30 mutants inhibited the human cancer K562 cells, indicating that these mutants acquired a capability to produce antitumor metabolites. HPLC-photodiode array detector (PDAD)-UV and HPLC-electron spray ionization (ESI)-MS analyses of the EtOAc extracts of seven bioactive mutants and the ZBY-3 strain indicated that diverse secondary metabolites have been newly produced in the mutant extracts in contrast to the ZBY-3 extract. The followed isolation and characterization demonstrated that six metabolites, cyclo(D-Pro-D-Phe) (1), cyclo(D-Tyr-D-Pro) (2), phenethyl 5-oxo-L-prolinate (3), cyclo(L-Ile-L-Pro) (4), cyclo(L-Leu-L-Pro) (5) and 3β,5α,9α-trihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6), were newly produced by the mutant u2n2h3-3 compared to the parent ZBY-3 strain. Compound 3 was a new compound; 2 was isolated from a natural source for the first time, and all of these compounds were also not yet found in the metabolites of other A. versicolor strains. Compounds 1-6 inhibited the K562 cells, with inhibition rates of 54.6% (1), 72.9% (2), 23.5% (3), 29.6% (4), 30.9% (5) and 51.1% (6) at 100 μg/mL, and inhibited also other human cancer HL-60, BGC-823 and HeLa cells, to some extent. The present study demonstrated the effectiveness of the ultrasound-mediated approach to activate silent metabolite production in fungi by introducing acquired resistance to aminoglycosides and its potential for discovering new compounds from silent fungal

  6. Use of antimicrobials in veterinary medicine and mechanisms of resistance.

    Science.gov (United States)

    Schwarz, S; Chaslus-Dancla, E

    2001-01-01

    This review deals with the application of antimicrobial agents in veterinary medicine and food animal production and the possible consequences arising from the widespread and multipurpose use of antimicrobials. The various mechanisms that bacteria have developed to escape the inhibitory effects of the antimicrobials most frequently used in the veterinary field are reported in detail. Resistance of bacteria to tetracyclines, macrolide-lincosamide-streptogramin antibiotics, beta-lactam antibiotics, aminoglycosides, sulfonamides, trimethoprim, fluoroquinolones and chloramphenicol/florfenicol is described with regard to enzymatic inactivation, decreased intracellular drug accumulation and modification/protection/replacement of the target sites. In addition, basic information is given about mobile genetic elements which carry the respective resistance genes, such as plasmids, transposons, and gene cassettes/integrons, and their ways of spreading via conjugation, mobilisation, transduction, and transformation.

  7. The relationship between the use of flucloxacillin, vancomycin, aminoglycosides and ciprofloxacin and the susceptibility patterns of coagulase-negative staphylococci recovered from blood cultures.

    NARCIS (Netherlands)

    Mulder, JG; Kosterink, JGW; Degener, JE

    1997-01-01

    Antibiotic use is a cause of selection of multiresistant bacterial strains. Over three years (1990-1992) we studied the relation between the use of flucloxacillin, vancomycin, aminoglycosides and ciprofloxacin and the susceptibility of coagulase-negative staphylococci (CNS) recovered from blood

  8. Surveillance of multidrug resistant suppurative infection causing bacteria in hospitalized patients in an Indian tertiary care hospital

    OpenAIRE

    Nabakishore Nayak; Rajesh K. Lenka; Rabindra N. Padhy

    2014-01-01

    Objective: To examine antibiograms of a cohort of suppurative bacteria isolated from wound-swabs from hospitalized patients of all economic groups of a typical Indian teaching hospital. Methods: In surveillance, antibiotic resistance patterns of 10 species of suppurative bacteria isolated from wound-swabs over a period of 24 months were recorded. Those were subjected to antibiotic sensitivity test, using 16 prescribed antibiotics of 5 different groups (3 aminoglycosides, 4 beta-lactams, 3 ...

  9. Abundance and distribution of antibiotic resistance genes in a full-scale anaerobic-aerobic system alternately treating ribostamycin, spiramycin and paromomycin production wastewater.

    Science.gov (United States)

    Tang, Mei; Dou, Xiaomin; Wang, Chunyan; Tian, Zhe; Yang, Min; Zhang, Yu

    2017-12-01

    The occurrence of antibiotic-resistant bacteria and antibiotic resistance genes (ARGs) has been intensively investigated for wastewater treatment systems treating single class of antibiotic in recent years. However, the impacts of alternately occurring antibiotics in antibiotic production wastewater on the behavior of ARGs in biological treatment systems were not well understood yet. Herein, techniques including high-capacity quantitative PCR and quantitative PCR (qPCR) were used to investigate the behavior of ARGs in an anaerobic-aerobic full-scale system. The system alternately treated three kinds of antibiotic production wastewater including ribostamycin, spiramycin and paromomycin, which referred to stages 1, 2 and 3. The aminoglycoside ARGs (52.1-79.3%) determined using high-capacity quantitative PCR were the most abundant species in all sludge samples of the three stages. The total relative abundances of macrolide-lincosamide-streptogramin (MLS) resistance genes and aminoglycoside resistance genes measured using qPCR were significantly higher (P  0.05) in both aerobic and anaerobic sludge samples. In aerobic sludge, one acetyltransferase gene (aacA4) and the other three nucleotidyltransferase genes (aadB, aadA and aadE) exhibited positive correlations with intI1 (r 2  = 0.83-0.94; P < 0.05), implying the significance of horizontal transfer in their proliferation. These results and facts will be helpful to understand the abundance and distribution of ARGs from antibiotic production wastewater treatment systems.

  10. In vitro susceptibility and resistance phenotypes in contemporary Enterobacter isolates in a university hospital in Crete, Greece.

    Science.gov (United States)

    Maraki, Sofia; Vardakas, Konstantinos Z; Samonis, George; Perdikis, Dimitrios; Mavromanolaki, Viktoria Eirini; Kofteridis, Diamantis P; Falagas, Matthew E

    2017-06-01

    To study the evolution in the susceptibility of Enterobacter spp. in Crete, Greece from 2010 to 2015. Non-duplicate isolates were studied using automated systems. Phenotypic confirmatory tests were applied. A total of 939 Enterobacter isolates were included. Colistin was the most active antibiotic (97.9%) followed by imipenem (96.1%), gentamicin (95.7%), tigecycline (91.8%), cefepime (89.4%), chloramphenicol (85.8%), fosfomycin (85.5%), trimethoprim/sulfamethoxazole (83.3%) and piperacillin/tazobactam (73.3%). Antibiotic resistance did not increase during the study period for most antibiotics. Lower susceptibility was observed among multidrug-resistant strains and carbapenem-nonsusceptible isolates. AmpC was the most common resistant mechanism (21%); carbapenemases (3.7%) and aminoglycoside-modifying enzymes (6.5%) were also detected. A significant proportion of Enterobacter spp. was resistant to several antibiotics, most notably β-lactams.

  11. Movement of foraging Tundra Swans explained by spatial pattern in cryptic food densities

    NARCIS (Netherlands)

    Klaassen, R.H.G.; Nolet, B.A.; Bankert, D.

    2006-01-01

    We tested whether Tundra Swans use information on the spatial distribution of cryptic food items (belowground Sago pondweed tubers) to shape their movement paths. In a continuous environment, swans create their own food patches by digging craters, which they exploit in several feeding bouts. Series

  12. A WWW-based information system on resistance of bacteria to antibiotics.

    Science.gov (United States)

    Schindler, J; Schindler, Z; Schindler, J

    1998-01-01

    The information system on resistance of bacteria to antibiotics (WARN--World Antibiotic Resistance Network) is implemented as a WWW server at Charles University in Prague (http:/(/)www.warn.cas.cz). Its main goal is to give information about problems of antibiotic resistance of bacteria and to process data on isolated strains. The WARN web-site contains six main topics. Four of them form the core of the system: Topics of Interest bring information on selected timely topics in antibiotic resistance--pneumococci, staphylococci, beta-lactamases, glycopeptide--and aminoglycoside resistance. Global Monitor brings references and reports on resistance in the world as well as recommended method of surveillance. The topic Data contains raw data on strains in particular countries and hospitals. Data can be viewed in their original form as a list of records (strains) or processed to provide statistics about the resistance rates in the selected country or hospital respectively. The topic Search allows one to search for one or several terms in the whole document. Counts of accessed pages show, that there is a standing demand for information about the serious problems of antibiotic therapy of infectious diseases.

  13. Identification and dynamics of a cryptic suture zone in tropical rainforest

    Science.gov (United States)

    Moritz, C.; Hoskin, C.J.; MacKenzie, J.B.; Phillips, B.L.; Tonione, M.; Silva, N.; VanDerWal, J.; Williams, S.E.; Graham, C.H.

    2009-01-01

    Suture zones, shared regions of secondary contact between long-isolated lineages, are natural laboratories for studying divergence and speciation. For tropical rainforest, the existence of suture zones and their significance for speciation has been controversial. Using comparative phylogeographic evidence, we locate a morphologically cryptic suture zone in the Australian Wet Tropics rainforest. Fourteen out of 18 contacts involve morphologically cryptic phylogeographic lineages, with mtDNA sequence divergences ranging from 2 to 15 per cent. Contact zones are significantly clustered in a suture zone located between two major Quaternary refugia. Within this area, there is a trend for secondary contacts to occur in regions with low environmental suitability relative to both adjacent refugia and, by inference, the parental lineages. The extent and form of reproductive isolation among interacting lineages varies across species, ranging from random admixture to speciation, in one case via reinforcement. Comparative phylogeographic studies, combined with environmental analysis at a fine-scale and across varying climates, can generate new insights into suture zone formation and to diversification processes in species-rich tropical rainforests. As arenas for evolutionary experimentation, suture zones merit special attention for conservation. PMID:19203915

  14. The novel kasugamycin 2'-N-acetyltransferase gene aac(2')-IIa, carried by the IncP island, confers kasugamycin resistance to rice-pathogenic bacteria.

    Science.gov (United States)

    Yoshii, Atsushi; Moriyama, Hiromitsu; Fukuhara, Toshiyuki

    2012-08-01

    Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the urgent need to understand the mechanism of resistance to KSM. Here, we identified a novel gene, aac(2')-IIa, encoding a KSM 2'-N-acetyltransferase from both KSM-resistant pathogens but not from KSM-sensitive bacteria. AAC(2')-IIa inactivates KSM, although it reveals no cross-resistance to other aminoglycosides. The aac(2')-IIa gene from B. glumae strain 5091 was identified within the IncP genomic island inserted into the bacterial chromosome, indicating the acquisition of this gene by horizontal gene transfer. Although excision activity of the IncP island and conjugational gene transfer was not detected under the conditions tested, circular intermediates containing the aac(2')-IIa gene were detected. These results indicate that the aac(2')-IIa gene had been integrated into the IncP island of a donor bacterial species. Molecular detection of the aac(2')-IIa gene could distinguish whether isolates are resistant or susceptible to KSM. This may contribute to the production of uninfected rice seeds and lead to the effective control of these pathogens by KSM.

  15. Barcoding against a paradox? Combined molecular species delineations reveal multiple cryptic lineages in elusive meiofaunal sea slugs

    Directory of Open Access Journals (Sweden)

    Jörger Katharina M

    2012-12-01

    Full Text Available Abstract Background Many marine meiofaunal species are reported to have wide distributions, which creates a paradox considering their hypothesized low dispersal abilities. Correlated with this paradox is an especially high taxonomic deficit for meiofauna, partly related to a lower taxonomic effort and partly to a high number of putative cryptic species. Molecular-based species delineation and barcoding approaches have been advocated for meiofaunal biodiversity assessments to speed up description processes and uncover cryptic lineages. However, these approaches show sensitivity to sampling coverage (taxonomic and geographic and the success rate has never been explored on mesopsammic Mollusca. Results We collected the meiofaunal sea-slug Pontohedyle (Acochlidia, Heterobranchia from 28 localities worldwide. With a traditional morphological approach, all specimens fall into two morphospecies. However, with a multi-marker genetic approach, we reveal multiple lineages that are reciprocally monophyletic on single and concatenated gene trees in phylogenetic analyses. These lineages are largely concordant with geographical and oceanographic parameters, leading to our primary species hypothesis (PSH. In parallel, we apply four independent methods of molecular based species delineation: General Mixed Yule Coalescent model (GMYC, statistical parsimony, Bayesian Species Delineation (BPP and Automatic Barcode Gap Discovery (ABGD. The secondary species hypothesis (SSH is gained by relying only on uncontradicted results of the different approaches (‘minimum consensus approach’, resulting in the discovery of a radiation of (at least 12 mainly cryptic species, 9 of them new to science, some sympatric and some allopatric with respect to ocean boundaries. However, the meiofaunal paradox still persists in some Pontohedyle species identified here with wide coastal and trans-archipelago distributions. Conclusions Our study confirms extensive, morphologically

  16. Cryptic extended brood care in the facultatively eusocial sweat bee Megalopta genalis.

    Science.gov (United States)

    Quiñones, A E; Wcislo, W T

    As a result of different brood cell provisioning strategies, nest-making insects may differ in the extent to which adults regularly provide extended parental care to their brood beyond nest defense. Mass-provisioning species cache the entire food supply needed for larval development prior to the oviposition and typically seal the brood cell. It is usually assumed that there is no regular contact between the adult(s) and brood. Here, we show that the bee, Megalopta genalis , expresses a form of cryptic brood care, which would not be observed during normal development. Following experimental injections of different provisioning materials into brood cells, foundresses reopened manipulated cells and the brood were aborted in some cases, implying that the foundresses assessed conditions within the cells. In aborted cells, foundresses sometimes laid a second egg after first removing dead larvae, previously stored pollen and contaminants. Our results show that hygienic brood care can be cryptic and hence may be more widespread than previously believed, lending support to the hypothesis that extended parental care is a preadaptation toward eusociality.

  17. Aspergillus niger contains the cryptic phylogenetic species A. awamori.

    Science.gov (United States)

    Perrone, Giancarlo; Stea, Gaetano; Epifani, Filomena; Varga, János; Frisvad, Jens C; Samson, Robert A

    2011-11-01

    Aspergillus section Nigri is an important group of species for food and medical mycology, and biotechnology. The Aspergillus niger 'aggregate' represents its most complicated taxonomic subgroup containing eight morphologically indistinguishable taxa: A. niger, Aspergillus tubingensis, Aspergillus acidus, Aspergillus brasiliensis, Aspergillus costaricaensis, Aspergillus lacticoffeatus, Aspergillus piperis, and Aspergillus vadensis. Aspergillus awamori, first described by Nakazawa, has been compared taxonomically with other black aspergilli and recently it has been treated as a synonym of A. niger. Phylogenetic analyses of sequences generated from portions of three genes coding for the proteins β-tubulin (benA), calmodulin (CaM), and the translation elongation factor-1 alpha (TEF-1α) of a population of A. niger strains isolated from grapes in Europe revealed the presence of a cryptic phylogenetic species within this population, A. awamori. Morphological, physiological, ecological and chemical data overlap occurred between A. niger and the cryptic A. awamori, however the splitting of these two species was also supported by AFLP analysis of the full genome. Isolates in both phylospecies can produce the mycotoxins ochratoxin A and fumonisin B₂, and they also share the production of pyranonigrin A, tensidol B, funalenone, malformins, and naphtho-γ-pyrones. In addition, sequence analysis of four putative A. awamori strains from Japan, used in the koji industrial fermentation, revealed that none of these strains belong to the A. awamori phylospecies. Copyright © 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  18. Activation of Antibiotic Production in Bacillus spp. by Cumulative Drug Resistance Mutations.

    Science.gov (United States)

    Tojo, Shigeo; Tanaka, Yukinori; Ochi, Kozo

    2015-12-01

    Bacillus subtilis strains produce a wide range of antibiotics, including ribosomal and nonribosomal peptide antibiotics, as well as bacilysocin and neotrehalosadiamine. Mutations in B. subtilis strain 168 that conferred resistance to drugs such as streptomycin and rifampin resulted in overproduction of the dipeptide antibiotic bacilysin. Cumulative drug resistance mutations, such as mutations in the mthA and rpsL genes, which confer low- and high-level resistance, respectively, to streptomycin, and mutations in rpoB, which confer resistance to rifampin, resulted in cells that overproduced bacilysin. Transcriptional analysis demonstrated that the enhanced transcription of biosynthesis genes was responsible for the overproduction of bacilysin. This approach was effective also in activating the cryptic genes of Bacillus amyloliquefaciens, leading to actual production of antibiotic(s). Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  19. Cryptic species Anopheles daciae (Diptera: Culicidae) found in the Czech Republic and Slovakia

    Czech Academy of Sciences Publication Activity Database

    Blažejová, Hana; Šebesta, Oldřich; Rettich, F.; Mendel, Jan; Čabanová, V.; Miterpáková, M.; Betášová, Lenka; Peško, Juraj; Hubálek, Zdeněk; Kampen, H.; Rudolf, Ivo

    2018-01-01

    Roč. 117, č. 1 (2018), s. 315-321 ISSN 0932-0113 R&D Projects: GA ČR(CZ) GA16-20054S Institutional support: RVO:68081766 Keywords : Anophelinae * Maculipennis complex * Anopheles daciae * Mosquitoes * Cryptic species * Vector-borne diseases Subject RIV: EG - Zoology Impact factor: 2.329, year: 2016

  20. Microbiology and antimicrobial susceptibility of otitis externa: a changing pattern of antimicrobial resistance.

    Science.gov (United States)

    Heward, E; Cullen, M; Hobson, J

    2018-04-01

    Otitis externa is a common presentation to secondary care otolaryngology clinics. Despite this, few studies have investigated the microbiology and antimicrobial resistance of otitis externa. This study aimed to examine these issues. Analysis identified 302 swabs taken from 217 patients (100 male, 117 female), between 1 January 2015 and 30 March 2016, at our rapid access otolaryngology clinic. In total, 315 organisms were isolated; the most frequent was Pseudomonas aeruginosa (31.1 per cent), followed by candida species (22.9 per cent) and Staphylococcus aureus (11.7 per cent). P aeruginosa was sensitive to ciprofloxacin in 97.7 per cent of cases and to gentamicin in 78.4 per cent. Compared with studies worldwide, the relative proportions of different organisms causing otitis externa and the patterns of antimicrobial resistance differ. Increasing resistance of P aeruginosa to aminoglycosides demonstrates a changing pattern of antimicrobial resistance that has not been previously reported. Reassuringly, quinolone antibiotics remain highly effective when treating P aeruginosa.

  1. DNA barcoding as a screening tool for cryptic diversity

    DEFF Research Database (Denmark)

    Huemer, Peter; Karsholt, Ole; Mutanen, Marko

    2014-01-01

    We explore the potential value of DNA barcode divergence for species delimitation in the genus Caryocolum Gregor & Povolný, 1954 (Lepidoptera, Gelechiidae), based on data from 44 European species (including 4 subspecies). Low intraspecific divergence of the DNA barcodes of the mtCOI (cytochrome c...... oxidase 1) gene and/or distinct barcode gaps to the nearest neighbor support species status for all examined nominal taxa. However, in 8 taxa we observed deep splits with a maximum intraspecific barcode divergence beyond a threshold of 3%, thus indicating possible cryptic diversity. The taxonomy...

  2. Cloning of Bacteroides fragilis plasmid genes affecting metronidazole resistance and ultraviolet survival in Escherichia coli

    International Nuclear Information System (INIS)

    Wehnert, G.U.; Abratt, V.R.; Goodman, H.J.; Woods, D.R.

    1990-01-01

    Since reduced metronidazole causes DNA damage, resistance to metronidazole was used as a selection method for the cloning of Bacteroides fragilis genes affecting DNA repair mechanisms in Escherichia coli. Genes from B. fragilis Bf-2 were cloned on a recombinant plasmid pMT100 which made E. coli AB1157 and uvrA, B, and C mutant strains more resistant to metronidazole, but more sensitive to far uv irradiation under aerobic conditions. The loci affecting metronidazole resistance and uv sensitivity were linked and located on a 5-kb DNA fragment which originated from the small 6-kb cryptic plasmid pBFC1 present in B. fragilis Bf-2 cells

  3. DNA barcoding reveals cryptic diversity within commercially exploited Indo-Malay Carangidae (Teleosteii: Perciformes.

    Directory of Open Access Journals (Sweden)

    Tun Nurul Aimi Mat Jaafar

    Full Text Available BACKGROUND: DNA barcodes, typically focusing on the cytochrome oxidase I gene (COI in many animals, have been used widely as a species-identification tool. The ability of DNA barcoding to distinguish species from a range of taxa and to reveal cryptic species has been well documented. Despite the wealth of DNA barcode data for fish from many temperate regions, there are relatively few available from the Southeast Asian region. Here, we target the marine fish Family Carangidae, one of the most commercially-important families from the Indo-Malay Archipelago (IMA, to produce an initial reference DNA barcode library. METHODOLOGY/PRINCIPAL FINDINGS: Here, a 652 bp region of COI was sequenced for 723 individuals from 36 putative species of Family Carangidae distributed within IMA waters. Within the newly-generated dataset, three described species exhibited conspecific divergences up to ten times greater (4.32-4.82% than mean estimates (0.24-0.39%, indicating a discrepancy with assigned morphological taxonomic identification, and the existence of cryptic species. Variability of the mitochondrial DNA COI region was compared within and among species to evaluate the COI region's suitability for species identification. The trend in range of mean K2P distances observed was generally in accordance with expectations based on taxonomic hierarchy: 0% to 4.82% between individuals within species, 0% to 16.4% between species within genera, and 8.64% to 25.39% between genera within families. The average Kimura 2-parameter (K2P distance between individuals, between species within genera, and between genera within family were 0.37%, 10.53% and 16.56%, respectively. All described species formed monophyletic clusters in the Neighbour-joining phylogenetic tree, although three species representing complexes of six potential cryptic species were detected in Indo-Malay Carangidae; Atule mate, Selar crumenophthalmus and Seriolina nigrofasciata. CONCLUSION/SIGNIFICANCE: This

  4. Multi-clonal evolution of multi-drug-resistant/extensively drug-resistant Mycobacterium tuberculosis in a high-prevalence setting of Papua New Guinea for over three decades

    Science.gov (United States)

    Bainomugisa, Arnold; Lavu, Evelyn; Hiashiri, Stenard; Majumdar, Suman; Honjepari, Alice; Moke, Rendi; Dakulala, Paison; Hill-Cawthorne, Grant A.; Pandey, Sushil; Marais, Ben J.; Coulter, Chris; Coin, Lachlan

    2018-01-01

    An outbreak of multi-drug resistant (MDR) tuberculosis (TB) has been reported on Daru Island, Papua New Guinea. Mycobacterium tuberculosis strains driving this outbreak and the temporal accrual of drug resistance mutations have not been described. Whole genome sequencing of 100 of 165 clinical isolates referred from Daru General Hospital to the Supranational reference laboratory, Brisbane, during 2012–2015 revealed that 95 belonged to a single modern Beijing sub-lineage strain. Molecular dating suggested acquisition of streptomycin and isoniazid resistance in the 1960s, with potentially enhanced virulence mediated by an mycP1 mutation. The Beijing sub-lineage strain demonstrated a high degree of co-resistance between isoniazid and ethionamide (80/95; 84.2 %) attributed to an inhA promoter mutation combined with inhA and ndh coding mutations. Multi-drug resistance, observed in 78/95 samples, emerged with the acquisition of a typical rpoB mutation together with a compensatory rpoC mutation in the 1980s. There was independent acquisition of fluoroquinolone and aminoglycoside resistance, and evidence of local transmission of extensively drug resistant (XDR) strains from 2009. These findings underline the importance of whole genome sequencing in informing an effective public health response to MDR/XDR TB. PMID:29310751

  5. Cryptic chemical identification as a crime intelligence aid.

    Science.gov (United States)

    Sturaro, A; Rella, R; Parvoli, G; Doretti, L

    1999-01-01

    A dead body was found near the sea and a commercial port in north-east Italy. The man had been shot and then burnt, by using a large volume of fire accelerant. The chemical composition of the flammable mixture had to be determined in order to aid police investigations. GC-MS analysis of residual cloth and soil identified a common gasoline, together with some unrelated compounds deriving from the container used to carry the inflammable liquid. A reconstruction of the event, an examination of the surroundings where the crime took place and the cryptic chemicals found, enabled the investigators to restrict and intensify their enquiries within a specific area.

  6. Detecting 16S rRNA Methyltransferases in Enterobacteriaceae by Use of Arbekacin.

    Science.gov (United States)

    McGann, Patrick; Chahine, Sarah; Okafor, Darius; Ong, Ana C; Maybank, Rosslyn; Kwak, Yoon I; Wilson, Kerry; Zapor, Michael; Lesho, Emil; Hinkle, Mary

    2016-01-01

    16S rRNA methyltransferases confer resistance to most aminoglycosides, but discriminating their activity from that of aminoglycoside-modifying enzymes (AMEs) is challenging using phenotypic methods. We demonstrate that arbekacin, an aminoglycoside refractory to most AMEs, can rapidly detect 16S methyltransferase activity in Enterobacteriaceae with high specificity using the standard disk susceptibility test. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  7. The Novel Kasugamycin 2′-N-Acetyltransferase Gene aac(2′)-IIa, Carried by the IncP Island, Confers Kasugamycin Resistance to Rice-Pathogenic Bacteria

    Science.gov (United States)

    Moriyama, Hiromitsu; Fukuhara, Toshiyuki

    2012-01-01

    Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the urgent need to understand the mechanism of resistance to KSM. Here, we identified a novel gene, aac(2′)-IIa, encoding a KSM 2′-N-acetyltransferase from both KSM-resistant pathogens but not from KSM-sensitive bacteria. AAC(2′)-IIa inactivates KSM, although it reveals no cross-resistance to other aminoglycosides. The aac(2′)-IIa gene from B. glumae strain 5091 was identified within the IncP genomic island inserted into the bacterial chromosome, indicating the acquisition of this gene by horizontal gene transfer. Although excision activity of the IncP island and conjugational gene transfer was not detected under the conditions tested, circular intermediates containing the aac(2′)-IIa gene were detected. These results indicate that the aac(2′)-IIa gene had been integrated into the IncP island of a donor bacterial species. Molecular detection of the aac(2′)-IIa gene could distinguish whether isolates are resistant or susceptible to KSM. This may contribute to the production of uninfected rice seeds and lead to the effective control of these pathogens by KSM. PMID:22660700

  8. Diversification and reproductive isolation: cryptic species in the only New World high-duty cycle bat, Pteronotus parnellii

    Directory of Open Access Journals (Sweden)

    Clare Elizabeth L

    2013-01-01

    Full Text Available Abstract Background Molecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely to speciate quickly. Pteronotus parnellii is a widespread Neotropical bat and the only New World species to use high-duty cycle echolocation, a trait otherwise restricted to Old World taxa. Here we analyze morphological and acoustic variation and genetic divergence at the mitochondrial COI gene, the 7th intron region of the y-linked Dby gene and the nuclear recombination-activating gene 2, and provide extensive evidence that P. parnellii is actually a cryptic species complex. Results Central American populations form a single species while three additional species exist in northern South America: one in Venezuela, Trinidad and western Guyana and two occupying sympatric ranges in Guyana and Suriname. Reproductive isolation appears nearly complete (only one potential hybrid individual found. The complex likely arose within the last ~6 million years with all taxa diverging quickly within the last ~1-2 million years, following a pattern consistent with the geological history of Central and northern South America. Significant variation in cranial measures and forearm length exists between three of the four groups, although no individual morphological character can discriminate these in the field. Acoustic analysis reveals small differences (5–10 kHz in echolocation calls between allopatric cryptic taxa that are unlikely to provide access to different prey resources but are consistent with divergence by drift in allopatric species or through selection for social recognition. Conclusions This unique approach, considering morphological, acoustic and multi-locus genetic information inherited maternally, paternally and bi-parentally, provides strong support to conclusions about the cessation of gene flow and

  9. Pinpointing cryptic borders: Fine-scale phylogeography and genetic landscape analysis of the Hormogaster elisae complex (Oligochaeta, Hormogastridae).

    Science.gov (United States)

    Marchán, Daniel F; Fernández, Rosa; de Sosa, Irene; Díaz Cosín, Darío J; Novo, Marta

    2017-07-01

    Spatial and temporal aspects of the evolution of cryptic species complexes have received less attention than species delimitation within them. The phylogeography of the cryptic complex Hormogaster elisae (Oligochaeta, Hormogastridae) lacks knowledge on several aspects, including the small-scale distribution of its lineages or the palaeogeographic context of their diversification. To shed light on these topics, a dense specimen collection was performed in the center of the Iberian Peninsula - resulting in 28 new H. elisae collecting points, some of them as close as 760m from each other- for a higher resolution of the distribution of the cryptic lineages and the relationships between the populations. Seven molecular regions were amplified: mitochondrial subunit 1 of cytochrome c oxidase (COI), 16S rRNA and tRNA Leu, Ala, and Ser (16S t-RNAs), one nuclear ribosomal gene (a fragment of 28S rRNA) and one nuclear protein-encoding gene (histone H3) in order to infer their phylogenetic relationships. Different representation methods of the pairwise divergence in the cytochrome oxidase I sequence (heatmap and genetic landscape graphs) were used to visualize the genetic structure of H. elisae. A nested approach sensu Mairal et al. (2015) (connecting the evolutionary rates of two datasets of different taxonomic coverage) was used to obtain one approximation to a time-calibrated phylogenetic tree based on external Clitellata fossils and a wide molecular dataset. Our results indicate that limited active dispersal ability and ecological or biotic barriers could explain the isolation of the different cryptic lineages, which never co-occur. Rare events of long distance dispersal through hydrochory appear as one of the possible causes of range expansion. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Molecular evidence of cryptic speciation in the "cosmopolitan" excavating sponge Cliona celata (Porifera, Clionaidae)

    NARCIS (Netherlands)

    Xavier, J.R.; Rachello-Dolmen, P.G.; Parra-Velandia, F.; Schönberg, C.H.L.; Breeuwer, J.A.J.; van Soest, R.W.M.

    2010-01-01

    Over the past several decades molecular tools have shown an enormous potential to aid in the clarification of species boundaries in the marine realm, particularly in morphologically simple groups. In this paper we report a case of cryptic speciation in an allegedly cosmopolitan and ecologically

  11. Azole-Resistance in Aspergillus terreus and Related Species: An Emerging Problem or a Rare Phenomenon?

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    Tamara Zoran

    2018-03-01

    Full Text Available Objectives: Invasive mold infections associated with Aspergillus species are a significant cause of mortality in immunocompromised patients. The most frequently occurring aetiological pathogens are members of the Aspergillus section Fumigati followed by members of the section Terrei. The frequency of Aspergillus terreus and related (cryptic species in clinical specimens, as well as the percentage of azole-resistant strains remains to be studied.Methods: A global set (n = 498 of A. terreus and phenotypically related isolates was molecularly identified (beta-tubulin, tested for antifungal susceptibility against posaconazole, voriconazole, and itraconazole, and resistant phenotypes were correlated with point mutations in the cyp51A gene.Results: The majority of isolates was identified as A. terreus (86.8%, followed by A. citrinoterreus (8.4%, A. hortai (2.6%, A. alabamensis (1.6%, A. neoafricanus (0.2%, and A. floccosus (0.2%. One isolate failed to match a known Aspergillus sp., but was found most closely related to A. alabamensis. According to EUCAST clinical breakpoints azole resistance was detected in 5.4% of all tested isolates, 6.2% of A. terreus sensu stricto (s.s. were posaconazole-resistant. Posaconazole resistance differed geographically and ranged from 0% in the Czech Republic, Greece, and Turkey to 13.7% in Germany. In contrast, azole resistance among cryptic species was rare 2 out of 66 isolates and was observed only in one A. citrinoterreus and one A. alabamensis isolate. The most affected amino acid position of the Cyp51A gene correlating with the posaconazole resistant phenotype was M217, which was found in the variation M217T and M217V.Conclusions:Aspergillus terreus was most prevalent, followed by A. citrinoterreus. Posaconazole was the most potent drug against A. terreus, but 5.4% of A. terreus sensu stricto showed resistance against this azole. In Austria, Germany, and the United Kingdom posaconazole-resistance in all A. terreus

  12. Taxonomic richness and abundance of cryptic peracarid crustaceans in the Puerto Morelos Reef National Park, Mexico

    Directory of Open Access Journals (Sweden)

    Luz Veronica Monroy-Velázquez

    2017-06-01

    Full Text Available Background and Aims Cryptic peracarids are an important component of the coral reef fauna in terms of diversity and abundance, yet they have been poorly studied. The aim of this study was to evaluate the taxonomic richness and abundance of cryptic peracarids in coral rubble in the Puerto Morelos Reef National Park, Mexico (PMRNP, and their relationship with depth. Methods Three reef sites were selected: (1 Bonanza, (2 Bocana, and (3 Jardines. At each site six kilograms of coral rubble were collected over four sampling periods at three depths: 3 m (back-reef, 6–8 m (fore-reef, and 10–12 m (fore-reef. Results A total of 8,887 peracarid crustaceans belonging to 200 taxa distributed over five orders and 63 families was obtained; 70% of the taxa were identified to species and 25% to genus level. Fifty species of those collected represent new records for the Mexican Caribbean Sea. Isopoda was the most speciose order while Tanaidacea was the most abundant. Discussion Cryptic peracarid taxonomic richness and abundance were related to depth with higher values of both parameters being found in the shallow (3 m back-reef, possibly due to a higher reef development and a greater accumulation of coral rubble produced during hurricanes. Peracarid data obtained in the present study can be used as a baseline for future monitoring programs in the PMRNP.

  13. Antimicrobial resistance in Salmonella spp. recovered from patients admitted to six different hospitals in Tehran, Iran from 2007 to 2008

    DEFF Research Database (Denmark)

    Tajbakhsh, Mercedeh; Hendriksen, Rene S.; Nochi, Zahra

    2012-01-01

    were screened for the presence of Salmonella, serotyped, tested for antimicrobial susceptibility using disk diffusion and examined for the presence of relevant resistance genes and integrons by PCR. A total of 1,120 patients were screened for the presence of Salmonella. Out of 71 Salmonella isolates...... recovered, the following serovars were identified: 17 Typhi, 14 Paratyphi C, 13 Enteritidis, 11 Paratyphi B, 10 Paratyphi A and six Infantis. Most resistance was observed towards sulfamethoxazole (30%), tetracyclines (25%), nalidixic acid (22%), spectinomycin (17%), trimethoprim (15%), ampicillin (14......%) and kanamycin (14%). The tetracycline resistance genes tet(A), tet(B), and tet(G) were found in 28%, 14% and 6% of the tetracycline resistant isolates, respectively. The genes aadA, aadB, strA, strB and aphA1-Iab were present in 83%, 55%, 34%, 1% and 17% of the aminoglycoside resistant isolates, respectively...

  14. Aminoglycoside-induced and non-syndromic hearing loss is associated with the G7444A mutation in the mitochondrial COI/tRNASer(UCN) genes in two Chinese families

    International Nuclear Information System (INIS)

    Zhu Yi; Qian Yaping; Tang Xiaowen; Wang Jindan; Yang Li; Liao Zhisu; Li Ronghua; Ji Jinzhang; Li Zhiyuan; Chen Jianfu; Choo, Daniel I.; Lu Jianxin; Guan Minxin

    2006-01-01

    We report here the clinical, genetic, and molecular characterization of two Chinese families with aminoglycoside induced and non-syndromic hearing impairment. Clinical and genetic evaluations revealed the variable severity and age-of-onset in hearing impairment in these families. Strikingly, there were extremely low penetrances of hearing impairment in these Chinese families. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the distinct sets of mtDNA polymorphism, in addition to the identical G7444A mutation associated with hearing loss. Indeed, the G7444A mutation in the CO1 gene and the precursor of tRNA Ser(UCN) gene is present in homoplasmy only in the maternal lineage of those pedigrees but not other members of these families and 164 Chinese controls. Their mitochondrial genomes belong to the Eastern Asian haplogroups C5a and D4a, respectively. In fact, the occurrence of the G7444A mutation in these several genetically unrelated subjects affected by hearing impairment strongly indicates that this mutation is involved in the pathogenesis of hearing impairment. However, there was the absence of other functionally significant mtDNA mutations in two Chinese pedigrees carrying the G7444A mutation. Therefore, nuclear modifier gene(s) or aminoglycoside(s) may play a role in the phenotypic expression of the deafness-associated G7444A mutation in these Chinese pedigrees

  15. Cryptic species? Patterns of maternal and paternal gene flow in eight neotropical bats.

    Directory of Open Access Journals (Sweden)

    Elizabeth L Clare

    Full Text Available Levels of sequence divergence at mitochondrial loci are frequently used in phylogeographic analysis and species delimitation though single marker systems cannot assess bi-parental gene flow. In this investigation I compare the phylogeographic patterns revealed through the maternally inherited mitochondrial COI region and the paternally inherited 7(th intron region of the Dby gene on the Y-chromosome in eight common Neotropical bat species. These species are diverse and include members of two families from the feeding guilds of sanguivores, nectarivores, frugivores, carnivores and insectivores. In each case, the currently recognized taxon is comprised of distinct, substantially divergent intraspecific mitochondrial lineages suggesting cryptic species complexes. In Chrotopterus auritus, and Saccopteryx bilineata I observed congruent patterns of divergence in both genetic regions suggesting a cessation of gene flow between intraspecific groups. This evidence supports the existence of cryptic species complexes which meet the criteria of the genetic species concept. In Glossophaga soricina two intraspecific groups with largely sympatric South American ranges show evidence for incomplete lineage sorting or frequent hybridization while a third group with a Central American distribution appears to diverge congruently at both loci suggesting speciation. Within Desmodus rotundus and Trachops cirrhosus the paternally inherited region was monomorphic and thus does not support or refute the potential for cryptic speciation. In Uroderma bilobatum, Micronycteris megalotis and Platyrrhinus helleri the gene regions show conflicting patterns of divergence and I cannot exclude ongoing gene flow between intraspecific groups. This analysis provides a comprehensive comparison across taxa and employs both maternally and paternally inherited gene regions to validate patterns of gene flow. I present evidence for previously unrecognized species meeting the criteria of

  16. Antimicrobial resistance of Pseudomonas spp. isolated from wastewater and wastewater-impacted marine coastal zone.

    Science.gov (United States)

    Luczkiewicz, Aneta; Kotlarska, Ewa; Artichowicz, Wojciech; Tarasewicz, Katarzyna; Fudala-Ksiazek, Sylwia

    2015-12-01

    In this study, species distribution and antimicrobial susceptibility of cultivated Pseudomonas spp. were studied in influent (INF), effluent (EFF), and marine outfall (MOut) of wastewater treatment plant (WWTP). The susceptibility was tested against 8 antimicrobial classes, active against Pseudomonas spp.: aminoglycosides, carbapenems, broad-spectrum cephalosporins from the 3rd and 4th generation, extended-spectrum penicillins, as well as their combination with the β-lactamase inhibitors, monobactams, fluoroquinolones, and polymyxins. Among identified species, resistance to all antimicrobials but colistin was shown by Pseudomonas putida, the predominant species in all sampling points. In other species, resistance was observed mainly against ceftazidime, ticarcillin, ticarcillin-clavulanate, and aztreonam, although some isolates of Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas pseudoalcaligenes, and Pseudomonas protegens showed multidrug-resistance (MDR) phenotype. Among P. putida, resistance to β-lactams and to fluoroquinolones as well as multidrug resistance become more prevalent after wastewater treatment, but the resistance rate decreased in marine water samples. Obtained data, however, suggests that Pseudomonas spp. are equipped or are able to acquire a wide range of antibiotic resistance mechanisms, and thus should be monitored as possible source of resistance genes.

  17. Genetics, morphology and ecology reveal a cryptic pika lineage in the Sikkim Himalaya.

    Science.gov (United States)

    Dahal, Nishma; Lissovsky, Andrey A; Lin, Zhenzhen; Solari, Katherine; Hadly, Elizabeth A; Zhan, Xiangjiang; Ramakrishnan, Uma

    2017-01-01

    Asian pika species are morphologically ∼similar and have overlapping ranges. This leads to uncertainty and species misidentification in the field. Phylogenetic analyses of such misidentified samples leads to taxonomic ambiguity. The ecology of many pika species remains understudied, particularly in the Himalaya, where sympatric species could be separated by elevation and/or substrate. We sampled, measured, and acquired genetic data from pikas in the Sikkim Himalaya. Our analyses revealed a cryptic lineage, Ochotona sikimaria, previously reported as a subspecies of O. thibetana. The results support the elevation of this lineage to the species level, as it is genetically divergent from O. thibetana, as well as sister species, O. cansus (endemic to central China) and O. curzoniae (endemic to the Tibetan plateau). The Sikkim lineage diverged from its sister species' about 1.7-0.8myrago, coincident with uplift events in the Himalaya. Our results add to the recent spate of cryptic diversity identified from the eastern Himalaya and highlight the need for further study within the Ochotonidae. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Cryptic variation in morphological evolution: HSP90 as a capacitor for loss of eyes in cavefish.

    Science.gov (United States)

    Rohner, Nicolas; Jarosz, Dan F; Kowalko, Johanna E; Yoshizawa, Masato; Jeffery, William R; Borowsky, Richard L; Lindquist, Susan; Tabin, Clifford J

    2013-12-13

    In the process of morphological evolution, the extent to which cryptic, preexisting variation provides a substrate for natural selection has been controversial. We provide evidence that heat shock protein 90 (HSP90) phenotypically masks standing eye-size variation in surface populations of the cavefish Astyanax mexicanus. This variation is exposed by HSP90 inhibition and can be selected for, ultimately yielding a reduced-eye phenotype even in the presence of full HSP90 activity. Raising surface fish under conditions found in caves taxes the HSP90 system, unmasking the same phenotypic variation as does direct inhibition of HSP90. These results suggest that cryptic variation played a role in the evolution of eye loss in cavefish and provide the first evidence for HSP90 as a capacitor for morphological evolution in a natural setting.

  19. The management of multidrug-resistant Enterobacteriaceae.

    Science.gov (United States)

    Bassetti, Matteo; Peghin, Maddalena; Pecori, Davide

    2016-12-01

    Multidrug-resistant (MDR) Enterobacteriaceae are often related to the production of extended-spectrum b-lactamases (ESBLs) and carbapenemase-producing Enterobacteriaceae (CRE), and represent an increasing global threat. Recommendations for the therapeutic management of MDR-related infections, however, are mainly derived from retrospective and nonrandomized prospective studies. The aim of this review is to discuss the challenges in the treatment of patients with infections because of MDR Enterobacteriaceae and provide an expert opinion while awaiting for more definitive data. To avoid the selection of carbapenemase-producing Enterobacteriaceae, carbapenem-sparing strategies should be considered. B-lactams/b-lactamase inhibitors, mainly piperacillin-tazobactam, minimum inhibitory concentration (MIC) 16/4mg/ml or less represents the best alternative to carbapenems for the treatment of ESBL-producing strains. Overall, combination therapy may be preferred over monotherapy for CRE. The combination of a carbapenem-containing regimen with colistin or high-dose tigecycline or aminoglycoside can be administered at high-dose prolonged infusion with therapeutic drug monitoring for the treatment of CRE with MIC for meropenem 8-16 mg/l or less. For MIC higher than 8-16 mg/l, the use of meropenem should be avoided and various combination therapies based on the in-vitro susceptibility of antimicrobials (e.g., colistin, high-dose tigecycline, fosfomycin, and aminoglycosides) should be selected. Carbapenem-sparing strategies should be used, when feasible, for ESBL infections. The majority of available nonrandomized studies highlight that combination for CRE seem to offer some therapeutic advantage over monotherapy. Strict infection control measures toward MDR Gram-negative pathogens remain necessary while awaiting for new treatment options.

  20. Antibiotic resistance of staphylococci from humans, food and different animal species according to data of the Hungarian resistance monitoring system in 2001.

    Science.gov (United States)

    Kaszanyitzky, Eva J; Jánosi, Sz; Egyed, Zsuzsanna; Agost, Gizella; Semjén, G

    2003-01-01

    Based on data of the Hungarian resistance monitoring system the antibiotic resistance of Staphylococcus strains of human and animal origin was studied. No methicillin-resistant staphylococci harbouring mecA gene were isolated from animals in 2001. Penicillin resistance, mediated by penicillinase production, was the most frequent among Staphylococcus aureus strains isolated from humans (96%), from bovine mastitis (55%), from foods (45%) and from dogs. In staphylococci isolated from animals low resistance percentages to aminoglycosides (0-2%), fluoroquinolones (0.5-3%) and sulphonamides (0.5-4%) were found but in strains isolated humans these figures were higher (1-14%, 5-18% and 3-31%, respectively). The most frequent antibiotic resistance profiles of strains isolated from animals and food were penicillin/tetracycline, penicillin/lincomycin and penicillin/lincomycin/tetracycline. Penicillin/tetracycline resistance was exhibited by strains from mastitis (3), samples from the meat industry (31), poultry flocks (1), poultry industry (1), noodle (1) and horses (2). Penicillin/lincomycin resistance was found in 10 Staphylococcus strains from mastitis, 1 from the dairy industry, 1 from the meat industry and 6 from dogs. Isolates from mastitis (2), from the dairy industry (2), from pigs (1), from the meat industry (1) and from poultry (1) harboured penicillin/lincomycin/tetracycline resistance pattern. Multiresistant strains were usually isolated only from one and sometimes from two animal species; therefore, the spread of defined resistant strains (clones) among different animal species could not be demonstrated. These results also suggest that the transfer of antibiotic resistance of S. aureus from animals to humans probably occurs less frequently than is generally assumed.

  1. CHARACTERIZATION OF SINGLE-STRAND ORIGINS OF CRYPTIC ROLLING-CIRCLE PLASMIDS FROM BACILLUS-SUBTILIS

    NARCIS (Netherlands)

    MEIJER, WJJ; VENEMA, G; BRON, S

    1995-01-01

    In this paper we describe the isolation and characterization of single strand origins (SSOs) of several cryptic Bacillus subtilis plasmids which use the rolling-circle mechanism of replication, The plasmids used in this study involved pTA1015, pTA1020, pTA1030, pTA1040, pTA1050 and pTA1060, The SSO

  2. Resistance pattern of clinical isolates of staphylococcus aureus against five groups of antibiotics

    International Nuclear Information System (INIS)

    Farzana, K.; Hameed, A.

    2006-01-01

    Among the samples received in pathology laboratory, Pakistan institute of Medical Science, Islamabad, 5069 samples had bacterial growth, among these 2580 (51%) samples were Gram-positive cocci and 1688 were Staphylococcus aureus during a period of two years. Out of these Gram-positive cocci 56% were resistant to penicillin group, 27% were resistant to cephalosporin group, 22% were resistant to aminoglycoside group 15% were resistant to quinolone group and 31% were resistant to other antibiotics (cotrimaxazole, erythromycin, aztreonam, vancomycin, nitrofurantion and meropenam). Antibio-grams of Gram-positive cocci were determined against various antibiotics by disc diffusion method. The rate of resistance to most of the antibiotics such as ampicillin, piperacillin, carbenicillin, penicillin, cephradine, cefotaxime, erythromycin, ceclor, ofloxacin, pefloxacin, ciprofloxacin, cotrimexazole (septran), gentamicin, meropenem, ceftazidime, erythromycin, tobramycin, enoxacin was higher when tested against the isolates collected from pus as compared to those from blood and urine. Antibiotic resistant strains were more prevalent in pus samples than other clinical isolates (blood and urine). The randomly selected 155 strains of Staphylococcus aureus when tested against five groups of antibiotics showed resistance rate against ampicillin (92%), cephradine (92%), cephradine (60%), and gentamicin (58%). However intermediate resistance was found in case of vancomicin (38%), in hospitalized and non-hospitalized patients. (author)

  3. Novel pathways for ameliorating the fitness cost of gentamicin resistant small colony variants

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Paulander, Wilhelm Erik Axel; Leng, Bingfeng

    2016-01-01

    Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby...... limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin. The SCVs carried...... mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500...

  4. Allopatric Speciation within a Cryptic Species Complex of Australasian Octopuses

    Science.gov (United States)

    Amor, Michael D.; Norman, Mark D.; Cameron, Hayley E.; Strugnell, Jan M.

    2014-01-01

    Despite extensive revisions over recent decades, the taxonomy of benthic octopuses (Family Octopodidae) remains in a considerable flux. Among groups of unresolved status is a species complex of morphologically similar shallow-water octopods from subtropical Australasia, including: Allopatric populations of Octopus tetricus on the eastern and western coasts of Australia, of which the Western Australian form is speculated to be a distinct or sub-species; and Octopus gibbsi from New Zealand, a proposed synonym of Australian forms. This study employed a combination of molecular and morphological techniques to resolve the taxonomic status of the ‘tetricus complex’. Phylogenetic analyses (based on five mitochondrial genes: 12S rRNA, 16S rRNA, COI, COIII and Cytb) and Generalised Mixed Yule Coalescent (GMYC) analysis (based on COI, COIII and Cytb) distinguished eastern and Western Australian O. tetricus as distinct species, while O. gibbsi was found to be synonymous with the east Australian form (BS = >97, PP = 1; GMYC p = 0.01). Discrete morphological differences in mature male octopuses (based on sixteen morphological traits) provided further evidence of cryptic speciation between east (including New Zealand) and west coast populations; although females proved less useful in morphological distinction among members of the tetricus complex. In addition, phylogenetic analyses suggested populations of octopuses currently treated under the name Octopus vulgaris are paraphyletic; providing evidence of cryptic speciation among global populations of O. vulgaris, the most commercially valuable octopus species worldwide. PMID:24964133

  5. Allopatric speciation within a cryptic species complex of Australasian octopuses.

    Science.gov (United States)

    Amor, Michael D; Norman, Mark D; Cameron, Hayley E; Strugnell, Jan M

    2014-01-01

    Despite extensive revisions over recent decades, the taxonomy of benthic octopuses (Family Octopodidae) remains in a considerable flux. Among groups of unresolved status is a species complex of morphologically similar shallow-water octopods from subtropical Australasia, including: Allopatric populations of Octopus tetricus on the eastern and western coasts of Australia, of which the Western Australian form is speculated to be a distinct or sub-species; and Octopus gibbsi from New Zealand, a proposed synonym of Australian forms. This study employed a combination of molecular and morphological techniques to resolve the taxonomic status of the 'tetricus complex'. Phylogenetic analyses (based on five mitochondrial genes: 12S rRNA, 16S rRNA, COI, COIII and Cytb) and Generalised Mixed Yule Coalescent (GMYC) analysis (based on COI, COIII and Cytb) distinguished eastern and Western Australian O. tetricus as distinct species, while O. gibbsi was found to be synonymous with the east Australian form (BS = >97, PP = 1; GMYC p = 0.01). Discrete morphological differences in mature male octopuses (based on sixteen morphological traits) provided further evidence of cryptic speciation between east (including New Zealand) and west coast populations; although females proved less useful in morphological distinction among members of the tetricus complex. In addition, phylogenetic analyses suggested populations of octopuses currently treated under the name Octopus vulgaris are paraphyletic; providing evidence of cryptic speciation among global populations of O. vulgaris, the most commercially valuable octopus species worldwide.

  6. Monitoring cryptic amphibians and reptiles in a Florida state park.

    Science.gov (United States)

    Engeman, Richard M; Meshaka, Walter E; Severson, Robert; Severson, Mary Ann; Kaufman, Greg; Groninger, N Paige; Smith, Henry T

    2016-04-01

    We monitored cryptic herpetofauna at Savannas Preserve State Park, Florida, by combining artificial cover counts with a quantitative paradigm for constructing and calculating population indices. Weekly indices were calculated from two consecutive days of data collection each week for 7 months from mid-winter to mid-summer in three habitats. Seventeen species were observed at least once, and time trends using index values were followed for six species. Among these, abundance and seasonal pattern information were obtained for an exotic species (greenhouse frog) and a species identified by the Florida Committee on Rare and Endangered Plants and Animals as threatened (Florida scrub lizard). We identified winter as the optimal time in this area to monitor populations for conducting annual assessments. This combined observation and indexing approach could provide managers or researchers with an economical means to quantitatively index population trends for multiple cryptic herpetofauna species simultaneously. Using artificial cover to sample within a population indexing design can be generalized beyond monitoring herpetofauna. Other forms of artificial cover that can be used as observation stations include aquatic artificial substrates, artificial tree cavities, artificial reefs, and other artificial aquatic structures and artificial sea grass units, among many others, and a wide range of taxa are suitable for population monitoring using artificial cover as observation stations in the approach we present, including insects, soil invertebrates, micro and macro aquatic invertebrates, fish, crustaceans, and small mammals.

  7. Isolation and characterization of two cryptic plasmids in the ammonia-oxidizing bacterium Nitrosomonas sp. strain ENI-11.

    Science.gov (United States)

    Yamagata, A; Kato, J; Hirota, R; Kuroda, A; Ikeda, T; Takiguchi, N; Ohtake, H

    1999-06-01

    Two plasmids were discovered in the ammonia-oxidizing bacterium Nitrosomonas sp. strain ENI-11, which was isolated from activated sludge. The plasmids, designated pAYS and pAYL, were relatively small, being approximately 1.9 kb long. They were cryptic plasmids, having no detectable plasmid-linked antibiotic resistance or heavy metal resistance markers. The complete nucleotide sequences of pAYS and pAYL were determined, and their physical maps were constructed. There existed two major open reading frames, ORF1 in pAYS and ORF2 in pAYL, each of which was more than 500 bp long. The predicted product of ORF2 was 28% identical to part of the replication protein of a Bacillus plasmid, pBAA1. However, no significant similarity to any known protein sequences was detected with the predicted product of ORF1. pAYS and pAYL had a highly homologous region, designated HHR, of 262 bp. The overall identity was 98% between the two nucleotide sequences. Interestingly, HHR-homologous sequences were also detected in the genomes of ENI-11 and the plasmidless strain Nitrosomonas europaea IFO14298. Deletion analysis of pAYS and pAYL indicated that HHR, together with either ORF1 or ORF2, was essential for plasmid maintenance in ENI-11. To our knowledge, pAYS and pAYL are the first plasmids found in the ammonia-oxidizing autotrophic bacteria.

  8. Occurrence of transferable antibiotic resistances in commercialized ready-to-eat mealworms (Tenebrio molitor L.).

    Science.gov (United States)

    Osimani, Andrea; Cardinali, Federica; Aquilanti, Lucia; Garofalo, Cristiana; Roncolini, Andrea; Milanović, Vesna; Pasquini, Marina; Tavoletti, Stefano; Clementi, Francesca

    2017-12-18

    The present study aimed to assess the occurrence of transferable determinants conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, beta-lactams, and aminoglycosides in 40 samples of commercialized edible mealworms (Tenebrio molitor L.) purchased from European Union (EU) and non-EU producers. A high prevalence of tet(K) was observed in all of the samples assayed, with percentages of PCR-based positivity that ranged from 80% (samples from Thailand) to 100% (samples from the Netherlands, Belgium and France). For macrolides, erm(B) prevailed, being detected in 57.5% of the samples assayed, whereas erm(A) and erm(C) were detected with lower frequencies. Genes for resistance to vancomycin were only detected in samples produced in France and Belgium, with 90% and 10% of the samples being positive for vanA, respectively. Beta-lactamase genes were found with low occurrence, whereas the gene aac-aph, conferring high resistance to aminoglycosides, was found in 40% of the samples produced in the Netherlands and Belgium and 20% of the samples produced in Thailand. The results of Principal Coordinate Analysis and Principal Component Analysis depicted a clean separation of the samples collected from the four producers based on the distribution of the 12 AR determinants considered. Given the growing interest on the use of mealworms as a novel protein source, AR detection frequencies found in the present study suggest further investigation into the use of antibiotics during rearing of this insect species and more extensive studies focused on the factors that can affect the diffusion of transferable ARs in the production chain. Until such studies are completed, prudent use of antibiotics during rearing of edible insects is recommended. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Will new antimicrobials overcome resistance among Gram-negatives?

    Science.gov (United States)

    Bassetti, Matteo; Ginocchio, Francesca; Mikulska, Małgorzata; Taramasso, Lucia; Giacobbe, Daniele Roberto

    2011-10-01

    The spread of resistance among Gram-positive and Gram-negative bacteria represents a growing challenge for the development of new antimicrobials. The pace of antibiotic drug development has slowed during the last decade and, especially for Gram-negatives, clinicians are facing a dramatic shortage in the availability of therapeutic options to face the emergency of the resistance problem throughout the world. In this alarming scenario, although there is a shortage of compounds reaching the market in the near future, antibiotic discovery remains one of the keys to successfully stem and maybe overcome the tide of resistance. Analogs of already known compounds and new agents belonging to completely new classes of antimicrobials are in early stages of development. Novel and promising anti-Gram-negative antimicrobials belong both to old (cephalosporins, carbapenems, β-lactamase inhibitors, monobactams, aminoglycosides, polymyxin analogues and tetracycline) and completely new antibacterial classes (boron-containing antibacterial protein synthesis inhibitors, bis-indoles, outer membrane synthesis inhibitors, antibiotics targeting novel sites of the 50S ribosomal subunit and antimicrobial peptides). However, all of these compounds are still far from being introduced into clinical practice. Therefore, infection control policies and optimization in the use of already existing molecules are still the most effective approaches to reduce the spread of resistance and preserve the activity of antimicrobials.

  10. Multiple drug resistance of Aeromonas hydrophila isolates from Chicken samples collected from Mhow and Indore city of Madhyapradesh

    Directory of Open Access Journals (Sweden)

    Kaskhedikar

    2009-02-01

    Full Text Available Fourteen antibacterial agents belonging to 9 different groups of antibiotics viz. aminoglycosides, cephalosporins, nitrofurantoin, fluroquinolones, chloramphenicol, sulphonamides, tetracyclines, penicillin and polymixin were used for in vitro sensitivity testing of Aeromonas hydrophila isolated from fifteen samples of chicken collected from retail shops in Mhow city. The sensitivity (100% was attributed to ciprofloxacin, cefuroxime, ceftriaxone, cephotaxime, chloramphenicol, gentamycin, kanamycin, nitrofurantoin, nalidixic acid and ofloxacin followed by oxytetracycline (50%. All the isolates were resistant to ampicillin and colistin antibiotics. That means, none of the isolates were found to be sensitive for penicillin and polymixin group of antibiotics. Multiple drug resistance was also observed in all A. hydrophila isolates. Out of total isolates, 100% were resistant to two antimicrobial drugs and 50% to three drugs. [Vet. World 2009; 2(1.000: 31-32

  11. Defining the Relationship Between Phenotypic and Genotypic Resistance Profiles of Multidrug-Resistant Enterobacterial Clinical Isolates.

    Science.gov (United States)

    Galal, Lamis; Abdel Aziz, Neveen A; Hassan, Walaa M

    2018-05-11

    Fluoroquinolones and aminoglycosides offer effective therapy for extended-spectrum beta-lactamase (ESBL)-producing enterobacterial infections, but their usefulness is threatened by increasing resistant strains. This study was conducted to demonstrate the phenotypic outcomes of the coexistence of genetic determinants mediating resistance to extended-spectrum cephalosporins and quinolones in enterobacterial isolates collected from patients with health-care-associated infections in Egypt. ESBL phenotype was determined using double-disk synergy test (DDST). The PCR technique was used to detect the presence of the genes mediating quinolone resistance (qnr and aac(6')-Ib-cr) and coexistence with ESBL genes. We also examined the association between the genetic makeup of the isolates and their resistance profiles including effect on MIC results. Phenotypically ESBLs were detected in 60-82% of the enterobacterial isolates. ESBL, qnr and aac(6')-Ib-cr genes were detected with the following percentages in Citrobacter isolates (69%, 69%, and 43%, respectively), E.coli isolates (65%, 70%, and 45%, respectively), Enterobacter isolates (56%, 67%, and 33%, respectively), and finally Klebsiella isolates (42%, 66%, and 25%, respectively). The coexistence of these multiresistant genetic elements significantly increased the MIC values of the tested antibiotics from different classes. We suggest using blaTEM, blaCTX-M-15, qnr, and aac(6')-Ib-cr genes for better and faster prediction of suitable antibiotic therapy with effective doses against ESBL-producing isolates harboring plasmid-mediated quinolone resistance (PMQR) determinants. Amikacin, meropenem, gentamicin, and imipenem seem to be better choices of treatment for such life-threatening infections, because of their remaining highest activity.

  12. Cryptic trace-element alteration of Anorthosite, Stillwater complex, Montana

    Science.gov (United States)

    Czamanske, G.K.; Loferski, P.J.

    1996-01-01

    Evidence of cryptic alteration and correlations among K, Ba, and LREE concentrations indicate that a post-cumulus, low-density aqueous fluid phase significantly modified the trace-element contents of samples from Anorthosite zones I and II of the Stillwater Complex, Montana. Concentrations of Ba, Ca, Co, Cr, Cu, Fe, Hf, K, Li, Mg, Mn, Na, Ni, Sc, Sr, Th, Zn, and the rare-earth elements (REE) were measured in whole rocks and plagioclase separates from five traverses across the two main plagioclase cumulate (anorthosite) zones and the contiguous cumulates of the Stillwater Complex in an attempt to better understand the origin and solidification of the anorthosites. However, nearly the entire observed compositional range for many trace elements can be duplicated at a single locality by discriminating between samples rich in oikocrystic pyroxene and those which are composed almost entirely of plagioclase and show anhedral-granular texture. Plagioclase separates with high trace-element contents were obtained from the pyroxene-poor samples, for which maps of K concentration show plagioclase grains to contain numerous fractures hosting a fine-grained, K-rich phase, presumed to be sericite. Secondary processes in layered intrusions have the potential to cause cryptic disturbance, and the utmost care must be taken to ensure that samples provide information about primary processes. Although plagioclase from Anorthosite zones I and II shows significant compositional variation, there are no systematic changes in the major- or trace-element compositions of plagioclase over as much as 630 m of anorthosite thickness or 18 km of strike length. Plagioclase in the two major anorthosite zones shows little distinction in trace-element concentrations from plagioclase in the cumulates immediately below, between, and above these zones.

  13. Molecules and morphology reveal cryptic variation among digeneans infecting sympatric mullets in the Mediterranean

    Czech Academy of Sciences Publication Activity Database

    Blasco-Costa, I.; Balbuena, J. A.; Raga, J. A.; Kostadinova, Aneta; Olson, P. D.

    2010-01-01

    Roč. 137, č. 2 (2010), s. 287-302 ISSN 0031-1820 R&D Projects: GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Digenea * Haploporidae * Saccocoelium * Mugilidae * cryptic species * molecules * morphology * rDNA Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.522, year: 2010

  14. Antibiotic resistance potential of the healthy preterm infant gut microbiome

    Directory of Open Access Journals (Sweden)

    Graham Rose

    2017-01-01

    Full Text Available Background Few studies have investigated the gut microbiome of infants, fewer still preterm infants. In this study we sought to quantify and interrogate the resistome within a cohort of premature infants using shotgun metagenomic sequencing. We describe the gut microbiomes from preterm but healthy infants, characterising the taxonomic diversity identified and frequency of antibiotic resistance genes detected. Results Dominant clinically important species identified within the microbiomes included C. perfringens, K. pneumoniae and members of the Staphylococci and Enterobacter genera. Screening at the gene level we identified an average of 13 antimicrobial resistance genes per preterm infant, ranging across eight different antibiotic classes, including aminoglycosides and fluoroquinolones. Some antibiotic resistance genes were associated with clinically relevant bacteria, including the identification of mecA and high levels of Staphylococci within some infants. We were able to demonstrate that in a third of the infants the S. aureus identified was unrelated using MLST or metagenome assembly, but low abundance prevented such analysis within the remaining samples. Conclusions We found that the healthy preterm infant gut microbiomes in this study harboured a significant diversity of antibiotic resistance genes. This broad picture of resistances and the wider taxonomic diversity identified raises further caution to the use of antibiotics without consideration of the resident microbial communities.

  15. Rising prevalence of antimicrobial resistance in urinary tract infections during pregnancy: Necessity for exploring newer treatment options

    Directory of Open Access Journals (Sweden)

    Meher Rizvi

    2011-01-01

    Full Text Available Background: Urinary tract infections (UTI are one of the most common medical complications of pregnancy. The emergence of drug resistance and particularly the Extended-spectrum beta-lactamase production by Escherichia coli and methicillin resistance in Staphylococci, limits the choice of antimicrobials. Materials and Methods: Patients in different stages of pregnancy with or without symptoms of urinary tract infection attending the antenatal clinic of obstetrics and gynaecology were screened for significant bacteriuria, by standard loop method on 5% sheep blood agar and teepol lactose agar. Isolates were identified by using standard biochemical tests and antimicrobial susceptibility testing was done using Kirby Bauer disc diffusion method. Results: A total of 4290 (51.2% urine samples from pregnant females showed growth on culture. Prevalence of asymptomatic bacteriuria 3210 (74.8% was higher than symptomatic UTI 1080 (25.2%. Escherichia coli was the most common pathogen accounting for 1800 (41.9% of the urinary isolates. Among the gram-positive cocci, coagulase negative species of Staphylococci 270 (6.4% were the most common pathogen. Significantly high resistance was shown by the gram negative bacilli as well as gram positive cocci to the β-lactam group of antimicrobials, flouroquinolones and aminoglycosides. Most alarming was the presence of ESBL in 846 (47% isolates of Escherichia coli and 344 (36.9% isolates of Klebsiella pneumoniae, along with the presence of methicillin resistance in 41% of Staphylococcus species and high-level aminoglycoside resistance in 45(30% isolates of Enterococcus species. Glycopeptides and carbepenems were the only group of drugs to which all the strains of gram positive cocci and gram negative bacilli were uniformly sensitive, respectively. Conclusions: Regular screening should be done for the presence of symptomatic or asymptomatic bacteriuria in pregnancy and specific guidelines should be issued for testing

  16. Systematic Review on Global Epidemiology of Methicillin-Resistant Staphylococcus pseudintermedius: Inference of Population Structure from Multilocus Sequence Typing Data

    DEFF Research Database (Denmark)

    dos Santos, Teresa Pires; Damborg, Peter; Moodley, Arshnee

    2016-01-01

    Background and rationale: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is a major cause of infections in dogs, also posing a zoonotic risk to humans. This systematic review aimed to determine the global epidemiology of MRSP and provide new insights into the population structure...... the MLST database for this species. Analysis of MLST data was performed with eBURST and ClonalFrame, and the proportion of MRSP isolates resistant to selected antimicrobial drugs was determined for the most predominant clonal complexes. Results: Fifty-eight studies published over the last 10 years were....... In Europe, CC258, which is more frequently susceptible to enrofloxacin and aminoglycosides, and more frequently resistant to sulphonamides/trimethoprim than CC71, is increasingly reported in various countries. CC68, previously described as the epidemic North American clone, is frequently reported...

  17. Subcellular mechanisms involved in apoptosis induced by aminoglycoside antibiotics: Insights on p53, proteasome and endoplasmic reticulum

    Energy Technology Data Exchange (ETDEWEB)

    Denamur, Sophie; Boland, Lidvine [Université catholique de Louvain, Louvain Drug Research Institute, Cellular and Molecular Pharmacology, UCL B1.73.05, avenue E. Mounier, 73 – B1200 Brussels (Belgium); Beyaert, Maxime [Université catholique de Louvain, de Duve Institute, Laboratory of Physiological Chemistry, UCL B1.75.08, avenue Hippocrate, 75 B -1200 Brussels (Belgium); Verstraeten, Sandrine L. [Université catholique de Louvain, Louvain Drug Research Institute, Cellular and Molecular Pharmacology, UCL B1.73.05, avenue E. Mounier, 73 – B1200 Brussels (Belgium); Fillet, Marianne [University of Liege, CIRM, Department of Pharmacy, Laboratory for the Analysis of Medicines, Quartier Hopital, Avenue Hippocrate, 15, B36, Tower 4, 4000 Liège 1 (Belgium); Tulkens, Paul M. [Université catholique de Louvain, Louvain Drug Research Institute, Cellular and Molecular Pharmacology, UCL B1.73.05, avenue E. Mounier, 73 – B1200 Brussels (Belgium); Bontemps, Françoise [Université catholique de Louvain, de Duve Institute, Laboratory of Physiological Chemistry, UCL B1.75.08, avenue Hippocrate, 75 B -1200 Brussels (Belgium); Mingeot-Leclercq, Marie-Paule [Université catholique de Louvain, Louvain Drug Research Institute, Cellular and Molecular Pharmacology, UCL B1.73.05, avenue E. Mounier, 73 – B1200 Brussels (Belgium)

    2016-10-15

    Gentamicin, an aminoglycoside used to treat severe bacterial infections, may cause acute renal failure. In the renal cell line LLC-PK1, gentamicin accumulates in lysosomes, induces alterations of their permeability, and triggers the mitochondrial pathway of apoptosis via activation of caspase-9 and -3 and changes in Bcl-2 family proteins. Early ROS production in lysosomes has been associated with gentamicin induced lysosomal membrane permeabilization. In order to better understand the multiple interconnected pathways of gentamicin-induced apoptosis and ensuing renal cell toxicity, we investigated the effect of gentamicin on p53 and p21 levels. We also studied the potential effect of gentamicin on proteasome by measuring the chymotrypsin-, trypsin- and caspase-like activities, and on endoplasmic reticulum by determining phopho-eIF2α, caspase-12 activation and GRP78 and 94. We observed an increase in p53 levels, which was dependent on ROS production. Accumulation of p53 resulted in accumulation of p21 and of phospho-eIF2α. These effects could be related to an impairment of proteasome as we demonstrated an inhibition of trypsin-and caspase-like activities. Moderate endoplasmic reticulum stress could also participate to cellular toxicity induced by gentamicin, with activation of caspase-12 without change in GRP74 and GRP98. All together, these data provide new mechanistic insights into the apoptosis induced by aminoglycoside antibiotics on renal cell lines. - Highlights: • Gentamicin induces apoptosis through p53 pathway. • Gentamicin inhibits proteosomal activity. • Gentamicin activates caspase-12.

  18. Subcellular mechanisms involved in apoptosis induced by aminoglycoside antibiotics: Insights on p53, proteasome and endoplasmic reticulum

    International Nuclear Information System (INIS)

    Denamur, Sophie; Boland, Lidvine; Beyaert, Maxime; Verstraeten, Sandrine L.; Fillet, Marianne; Tulkens, Paul M.; Bontemps, Françoise; Mingeot-Leclercq, Marie-Paule

    2016-01-01

    Gentamicin, an aminoglycoside used to treat severe bacterial infections, may cause acute renal failure. In the renal cell line LLC-PK1, gentamicin accumulates in lysosomes, induces alterations of their permeability, and triggers the mitochondrial pathway of apoptosis via activation of caspase-9 and -3 and changes in Bcl-2 family proteins. Early ROS production in lysosomes has been associated with gentamicin induced lysosomal membrane permeabilization. In order to better understand the multiple interconnected pathways of gentamicin-induced apoptosis and ensuing renal cell toxicity, we investigated the effect of gentamicin on p53 and p21 levels. We also studied the potential effect of gentamicin on proteasome by measuring the chymotrypsin-, trypsin- and caspase-like activities, and on endoplasmic reticulum by determining phopho-eIF2α, caspase-12 activation and GRP78 and 94. We observed an increase in p53 levels, which was dependent on ROS production. Accumulation of p53 resulted in accumulation of p21 and of phospho-eIF2α. These effects could be related to an impairment of proteasome as we demonstrated an inhibition of trypsin-and caspase-like activities. Moderate endoplasmic reticulum stress could also participate to cellular toxicity induced by gentamicin, with activation of caspase-12 without change in GRP74 and GRP98. All together, these data provide new mechanistic insights into the apoptosis induced by aminoglycoside antibiotics on renal cell lines. - Highlights: • Gentamicin induces apoptosis through p53 pathway. • Gentamicin inhibits proteosomal activity. • Gentamicin activates caspase-12.

  19. Cross-shelf investigation of coral reef cryptic benthic organisms reveals diversity patterns of the hidden majority

    KAUST Repository

    Pearman, John K.; Leray, M.; Villalobos, R.; Machida, R. J.; Berumen, Michael L.; Knowlton, N.; Carvalho, Susana

    2018-01-01

    (ARMS) and amplicon sequencing methodologies, targeting mitochondrial cytochrome oxidase I and 18S rRNA genes, to investigate changes in the cryptic reef biodiversity. ARMS, deployed at 11 sites across a near- to off-shore gradient in the Red Sea were

  20. Divergence in cryptic leaf colour provides local camouflage in an alpine plant.

    Science.gov (United States)

    Niu, Yang; Chen, Zhe; Stevens, Martin; Sun, Hang

    2017-10-11

    The efficacy of camouflage through background matching is highly environment-dependent, often resulting in intraspecific colour divergence in animals to optimize crypsis in different visual environments. This phenomenon is largely unexplored in plants, although several lines of evidence suggest they do use crypsis to avoid damage by herbivores. Using Corydalis hemidicentra, an alpine plant with cryptic leaf colour, we quantified background matching between leaves and surrounding rocks in five populations based on an approximate model of their butterfly enemy's colour perception. We also investigated the pigment basis of leaf colour variation and the association between feeding risk and camouflage efficacy. We show that plants exhibit remarkable colour divergence between populations, consistent with differences in rock appearances. Leaf colour varies because of a different quantitative combination of two basic pigments-chlorophyll and anthocyanin-plus different air spaces. As expected, leaf colours are better matched against their native backgrounds than against foreign ones in the eyes of the butterfly. Furthermore, improved crypsis tends to be associated with a higher level of feeding risk. These results suggest that divergent cryptic leaf colour may have evolved to optimize local camouflage in various visual environments, extending our understanding of colour evolution and intraspecific phenotype diversity in plants. © 2017 The Author(s).

  1. Evaluation of levels of antibiotic resistance in groundwater-derived E. coli isolates in the Midwest of Ireland and elucidation of potential predictors of resistance

    Science.gov (United States)

    O'Dwyer, Jean; Hynds, Paul; Pot, Matthieu; Adley, Catherine C.; Ryan, Michael P.

    2017-06-01

    Antibiotic-resistant (pathogenic and non-pathogenic) organisms and genes are now acknowledged as significant emerging aquatic contaminants with potentially adverse human and ecological health impacts, and thus require monitoring. This study is the first to investigate levels of resistance among Irish groundwater (private wells) samples; Escherichia coli isolates were examined against a panel of commonly prescribed human and veterinary therapeutic antibiotics, followed by determination of the causative factors of resistance. Overall, 42 confirmed E. coli isolates were recovered from a groundwater-sampling cohort. Resistance to the human panel of antibiotics was moderate; nine (21.4%) E. coli isolates demonstrated resistance to one or more human antibiotics. Conversely, extremely high levels of resistance to veterinary antibiotics were found, with all isolates presenting resistance to one or more veterinary antibiotics. Particularly high levels of resistance (93%) were found with respect to the aminoglycoside class of antibiotics. Results of statistical analysis indicate a significant association between the presence of human (multiple) antibiotic resistance ( p = 0.002-0.011) and both septic tank density and the presence of vulnerable sub-populations (<5 years). For the veterinary antibiotics, results point to a significant relationship ( p = <0.001) between livestock (cattle) density and the prevalence of multiple antibiotic resistant E. coli. Groundwater continues to be an important resource in Ireland, particularly in rural areas; thus, results of this preliminary study offer a valuable insight into the prevalence of antibiotic resistance in the hydrogeological environment and establish a need for further research with a larger geological diversity.

  2. Prevalence and Antimicrobial Resistance of Enterococcus Species: A Hospital-Based Study in China

    Directory of Open Access Journals (Sweden)

    Wei Jia

    2014-03-01

    Full Text Available Objective: to investigate the prevalence and antimicrobial resistance of Enterococcus species isolated from a university hospital, and explore the mechanisms underlying the antimicrobial resistance, so as to provide clinical evidence for the inappropriate clinical use of antimicrobial agents and the control and prevention of enterococcal infections. Methods: a total of 1,157 enterococcal strains isolated from various clinical specimens from January 2010 to December 2012 in the General Hospital of Ningxia Medical University were identified to species level with a VITEK-2 COMPACT fully automated microbiological system, and the antimicrobial susceptibility of Enterococcus species was determined using the Kirby-Bauer disc diffusion method. The multiple-drug resistant enterococcal isolates were screened from the clinical isolates of Enterococcus species from the burns department. The minimal inhibitory concentration (MIC of Enterococcus species to the three fluoroquinolones, including ciprofloxacin, gatifloxacin and levofloxacin was determined with the agar dilution method, and the changes in the MIC of Enterococcus species to the three fluoroquinolones following reserpine treatment were evaluated. The β-lactam, aminoglycoside, tetracycline, macrolide, glycopeptide resistance genes and the efflux pump emeA genes were detected in the enterococcal isolates using a polymerase chain reaction (PCR assay. Results: the 1,157 clinical isolates of Enterococcus species included 679 E. faecium isolates (58.7%, 382 E. faecalis isolates (33%, 26 E. casseliflavus isolates (2.2%, 24 E. avium isolates (2.1%, and 46 isolates of other Enterococcus species (4%. The prevalence of antimicrobial resistance varied significantly between E. faecium and E. faecalis, and ≤1.1% of these two Enterococcus species were found to be resistant to vancomycin, teicoplanin or linezolid. In addition, the Enterococcus species isolated from different departments of the hospital

  3. Integrative taxonomy detects cryptic and overlooked fish species in a neotropical river basin.

    Science.gov (United States)

    Gomes, Laís Carvalho; Pessali, Tiago Casarim; Sales, Naiara Guimarães; Pompeu, Paulo Santos; Carvalho, Daniel Cardoso

    2015-10-01

    The great freshwater fish diversity found in the neotropical region makes management and conservation actions challenging. Due to shortage of taxonomists and insufficient infrastructure to deal with such great biodiversity (i.e. taxonomic impediment), proposed remedies to accelerate species identification and descriptions include techniques that combine DNA-based identification and concise morphological description. The building of a DNA barcode reference database correlating meristic and genetic data was developed for 75 % of the Mucuri River basin's freshwater fish. We obtained a total of 141 DNA barcode sequences from 37 species belonging to 30 genera, 19 families, and 5 orders. Genetic distances within species, genera, and families were 0.74, 9.5, and 18.86 %, respectively. All species could be clearly identified by the DNA barcodes. Divergences between meristic morphological characteristics and DNA barcodes revealed two cryptic species among the Cyphocharax gilbert and Astyanax gr. bimaculatus specimens, and helped to identify two overlooked species within the Gymnotus and Astyanax taxa. Therefore, using a simplified model of neotropical biodiversity, we tested the efficiency of an integrative taxonomy approach for species discovery, identification of cryptic diversity, and accelerating biodiversity descriptions.

  4. Screening of nasal carriage of methicillin-resistant Staphylococcus aureus during admission of patients to Frantz Fanon Hospital, Blida, Algeria

    Directory of Open Access Journals (Sweden)

    Mohamed Amine Ouidri

    2018-05-01

    Full Text Available A study was performed of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA strains isolated from nasal preoperative samples. Of 663 samples assessed, staphylococcus was detected in 143 (21.57%. The disc diffusion method (cefoxitin 30 μg, a screening test (oxacillin 6 μg/mL and a search for Protein Binding Additional Penicillin 2 (PLP2a allowed the detection and confirmation of resistance to methicillin for 36 strains, a rate of 5.43% of the total population studied. Eight MRSA carriers received care in the trauma service, 14 in cardiology, five in ear, nose and throat, four in neurosurgery and paediatrics, and one in SCI. Thirty-six methicillin-resistant of the nasal portage strains are in their great majority, 27 of 36, rather limited multi-R character (two to three families namely resistance: tetracyclines, fluoroquinolones, aminoglycosides, macrolides. One of the MRSA strains was found to have intermediate sensitivity to vancomycin. Keywords: Antibiotic resistance, Healthy volunteers, MRSA, Prevalence, Staphylococcus aureus

  5. Allopatric origin of cryptic butterfly species that were discovered feeding on distinct host plants in sympatry.

    NARCIS (Netherlands)

    McBride, L.C.; Velzen, van R.; Larsen, T.B.

    2009-01-01

    Surveys of tropical insects are increasingly uncovering cryptic species ¿ morphologically similar yet reproductively isolated taxa once thought to comprise a single interbreeding entity. The vast majority of such species are described from a single location. This leaves us with little information on

  6. Antimicrobial resistance of bacterial pathogens in a Neonatal Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Farzana Ahmed

    2018-03-01

    Full Text Available The aim of this study was to identify the antimicrobial susceptibility pattern and relevant treatment options in a neonatal intensive care unit from January 2012 and June 2016. Out of the total 78 culture positive samples, Gram positive and Gram negative microorganisms were 26% and 74% respectively. Acinetobacter remained the predominant isolate (32.1% followed by Klebsiella species (18.0%. Most of the Gram positive isolates exhibited higher resistance to penicillin, cephalosporin, macrolides, gentamycin and quinolones. Gram positive isolates had sensitivity of 100% to linezolid, vancomycin, chloramphenicol followed by rifampicin (84%. In comparison to other commonly used antibiotics, sensitivity to these four medicines was statistically significant (p<0.05. Similarly, most of the Gram negative bacteria showed resistance to cephalosporin, aminoglycosides. About two-third cases showed resistant to meropenum, quinolones and combination preparation of piperacillin and tazobactam. Overall sensitivity among the Gram negative isolates was to polymixin B (100% and minocycline (97%, followed by colistin (83%. In comparison to other commonly used antibiotics, sensitivity to these three medicines was statistically significant (p<0.05.

  7. Evolution in karst massifs: Cryptic diversity among bent-toed geckos along the Truong Son Range with descriptions of three new species and one new country record from Laos.

    Science.gov (United States)

    Luu, Vinh Quang; Bonkowski, Michael; Nguyen, Truong Quang; Le, Minh Duc; Schneider, Nicole; Ngo, Hanh Thi; Ziegler, Thomas

    2016-05-02

    Species designated as 'cryptic' share a similar morphotype, and are often only clearly separable by molecular data. Cyrtodactylus, the most diverse gecko genus of the family Gekkonidae, is a prime example, because many morphologically similar taxa have only recently been identified as new species as a result of available genetic evidence. However, while cryptic diversity of Cyrtodactylus is already well documented on the Vietnamese side of the Truong Son range, only scarce data is available from central Laos. In this study, we address this issue by means of an integrative approach, which employs morphological, molecular, and ecological data to distinguish cryptic species of the Cyrtodacylus phongnhakebangensis species group primarily distributed along the northern Truong Son Range. Our analyses based on 12 selected morphological characters, a partial mitochondrial gene (COI), and five ecological parameters revealed three undescribed cryptic Cyrtodactylus species from Hin Nam No National Protected Area, which are described as Cyrtodactylus calamei sp. nov., Cyrtodactylus hinnamnoensis sp. nov., and Cyrtodactylus sommerladi sp. nov. A fourth discovered Cyrtodactylus population in Hin Nam No proved to be the first country record of C. cryptus for Laos. Our results highlight the importance of applying an integrative approach to resolving the taxonomy of complex and cryptic species groups, and the role of the Truong Son Range in maintaining the high level of biodiversity over time.

  8. Resistance patterns of bacterial isolates to antimicrobials from 3 hospitals in the United Arab Emirates

    International Nuclear Information System (INIS)

    AlDhaheri, Ahmed S; AlNiyadi, Mohammed S; AlDhaheri Ahmed D; Bastaki, Salim M

    2009-01-01

    To compare the resistance pattern of common bacterial pathogens to commonly used drugs. Information and statistics of antimicrobial resistance for 1994 and 2005 were collected from the 3 hospital microbiology laboratories in the United Arab Emirates. The resistance patterns of Staphylococcus aureus, Escherichia coli, Klebsiella spp, and Pseudomonas aeruginosa to several front-line drugs were estimated. All laboratories used automatic machines (Vitek 2), which identifies and determines minimum inhibitory concentrations simultaneously. Increased resistance was observed for Staphylococcus aureus, (n=315, 2005) to erythromycin (approximately 6 fold, Al-Ain Hospital only), cloxacillin (Al-Ain Hospital), and gentamicin (more than 3-10 folds in all hospitals). Increased penicillin resistance was not observed. For the common Gram-negative organisms, there was a high resistance to ampicillin, gentamicin, ceftriaxone, ciprofloxacin, and imipenem, which seemed to increase for Escherichia coli, (by 4.2-200%, n=305, 2005); however, there was very little resistance to imipenem (0.4%) in Tawam Hospital. Variable resistance patterns were obtained for Pseudomonas aeruginosa (n=316, 2005) and Klebsiella spp,(n=316, 2005) against aminoglycosides, cephalosporins, ciprofloxacin, and norfloxacin. Overall, there was an obvious increase in resistance of bacteria and the prevalence rate to a number of drugs from 1-120 folds during the 11-year period. (author)

  9. Antimicrobial resistance among Enterobacteriaceae in South America: history, current dissemination status and associated socioeconomic factors.

    Science.gov (United States)

    Bonelli, Raquel Regina; Moreira, Beatriz Meurer; Picão, Renata Cristina

    2014-04-01

    South America exhibits some of the higher rates of antimicrobial resistance in Enterobactericeae worldwide. This continent includes 12 independent countries with huge socioeconomic differences, where the ample access to antimicrobials, including counterfeit ones, coexists with ineffective health systems and sanitation problems, favoring the emergence and dissemination of resistant strains. This work presents a literature review concerning the evolution and current status of antimicrobial resistance threats found among Enterobacteriaceae in South America. Resistance to β-lactams, fluoroquinolones and aminoglycosides was emphasized along with description of key epidemiological studies that highlight the success of specific resistance determinants in different parts of the continent. In addition, a discussion regarding political and socioeconomic factors possibly related to the dissemination of antimicrobial resistant strains in clinical settings and at the community is presented. Finally, in order to assess the possible sources of resistant bacteria, we compile the current knowledge about the occurrence of antimicrobial resistance in isolates in South American' food, food-producing animals and off-hospitals environments. By addressing that intensive intercontinental commerce and tourism neutralizes the protective effect of geographic barriers, we provide arguments reinforcing that globally integrated efforts are needed to decelerate the emergence and dissemination of antimicrobial resistant strains. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Phenotypic and Genotypic Antibiotic Resistance of Salmonella from Chicken Carcasses Marketed at Ibague, Colombia

    Directory of Open Access Journals (Sweden)

    D Cortes Vélez

    Full Text Available ABSTRACT Salmonella enterica is responsible for alimentary toxic infections associated with the consumption of contaminated poultry products and the antimicrobial resistant patterns of Salmonella circulating in the Tolima region are currently unknown. To address this issue, both the phenotype and genotype antibiotic resistance patterns of 47 Salmonella isolated from raw chicken carcasses sold at the Ibague city were analyzed by the disc diffusion, microdilution and PCR assays. All 47 Salmonella isolates showed resistance to five or more antimicrobial agents. Resistance to Ampicillin (AMP, Amikacin (AMK, Gentamicin (GEN, Tobramycin (TOB, Cefazoline (CFZ, Cefoxitin (FOX, Nitrofurantoin (NIT, Trimethoprim-Sulfamethoxazole (SXT, Tetracycline (TET, Ciprofloxacin (CIP and Enrofloxacin (ENR was observed in 42.35% of Salmonella isolates. All tested S. Paratyphi B var Java isolates showed resistance to at least 12 antibiotics. S. Hvittingfoss showed resistance to 5 antibiotics, whereas S. Muenster showed resistance to seven antibiotics. Amplification of a number of antibiotic resistance genes showed that blaTEM (100% correlated well with resistance to Ampicilin and Cephalosporin, whereas aadB (87% correlated well with resistance to Aminoglycosides. It is concluded that Salmonella isolated from raw chicken meat marketed at Ibague showed MDR by both phenotypic and genotypic methods and they may represent an important threat to human health. Additional studies are needed to establish the relationship between antibiotic resistance in Salmonella from poultry products and clinical isolates.

  11. Mitochondrial 12S ribosomal RNA A1555G mutation associated with cardiomyopathy and hearing loss following high-dose chemotherapy and repeated aminoglycoside exposure

    DEFF Research Database (Denmark)

    Skou, Anne-Sofie; Tranebjærg, Lisbeth; Jensen, Tim

    2014-01-01

    A 19-month-old girl with the A1555G mitochondrial mutation in the 12S ribosomal RNA gene and acute myelogenous leukemia developed dilated cardiomyopathy and bilateral sensorineural hearing loss before undergoing allogeneic stem cell transplantation. She had received gentamicin during episodes of ...... of febrile neutropenia. Testing for the A1555G mutation is recommended in patients frequently treated with aminoglycosides....

  12. Nest Construction by a Ground-nesting Bird Represents a Potential Trade-off Between Egg Crypticity and Thermoregulation

    Science.gov (United States)

    Predation selects against conspicuous colors in bird eggs and nests, while thermoregulatory constraints select for nest building behavior that regulates incubation temperatures. We present results that reveal a trade-off between nest crypticity and thermoregulation of eggs base...

  13. Coproduction of Novel 16S rRNA Methylase RmtD and Metallo-β-Lactamase SPM-1 in a Panresistant Pseudomonas aeruginosa Isolate from Brazil▿

    OpenAIRE

    Doi, Yohei; de Oliveira Garcia, Doroti; Adams, Jennifer; Paterson, David L.

    2006-01-01

    Serious infections with Pseudomonas aeruginosa are frequently treated with the combination of a β-lactam antimicrobial and an aminoglycoside. P. aeruginosa strain PA0905 was isolated in 2005 from an inpatient in Brazil. It showed a panresistant phenotype that included resistance to β-lactams, aminoglycosides, and fluoroquinolones. The β-lactam resistance was conferred by the production of the metallo-β-lactamase SPM-1. No inhibitory zone was observed when a disk diffusion test was performed w...

  14. Medical data sheet in safe havens - A tri-layer cryptic solution.

    Science.gov (United States)

    Praveenkumar, Padmapriya; Amirtharajan, Rengarajan; Thenmozhi, K; Balaguru Rayappan, John Bosco

    2015-07-01

    Secured sharing of the diagnostic reports and scan images of patients among doctors with complementary expertise for collaborative treatment will help to provide maximum care through faster and decisive decisions. In this context, a tri-layer cryptic solution has been proposed and implemented on Digital Imaging and Communications in Medicine (DICOM) images to establish a secured communication for effective referrals among peers without compromising the privacy of patients. In this approach, a blend of three cryptic schemes, namely Latin square image cipher (LSIC), discrete Gould transform (DGT) and Rubik׳s encryption, has been adopted. Among them, LSIC provides better substitution, confusion and shuffling of the image blocks; DGT incorporates tamper proofing with authentication; and Rubik renders a permutation of DICOM image pixels. The developed algorithm has been successfully implemented and tested in both the software (MATLAB 7) and hardware Universal Software Radio Peripheral (USRP) environments. Specifically, the encrypted data were tested by transmitting them through an additive white Gaussian noise (AWGN) channel model. Furthermore, the sternness of the implemented algorithm was validated by employing standard metrics such as the unified average changing intensity (UACI), number of pixels change rate (NPCR), correlation values and histograms. The estimated metrics have also been compared with the existing methods and dominate in terms of large key space to defy brute force attack, cropping attack, strong key sensitivity and uniform pixel value distribution on encryption. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Genome-based insights into the resistome and mobilome of multidrug-resistant Aeromonas sp. ARM81 isolated from wastewater.

    Science.gov (United States)

    Adamczuk, Marcin; Dziewit, Lukasz

    2017-01-01

    The draft genome of multidrug-resistant Aeromonas sp. ARM81 isolated from a wastewater treatment plant in Warsaw (Poland) was obtained. Sequence analysis revealed multiple genes conferring resistance to aminoglycosides, β-lactams or tetracycline. Three different β-lactamase genes were identified, including an extended-spectrum β-lactamase gene bla PER-1 . The antibiotic susceptibility was experimentally tested. Genome sequencing also allowed us to investigate the plasmidome and transposable mobilome of ARM81. Four plasmids, of which two carry phenotypic modules (i.e., genes encoding a zinc transporter ZitB and a putative glucosyltransferase), and 28 putative transposase genes were identified. The mobility of three insertion sequences (isoforms of previously identified elements ISAs12, ISKpn9 and ISAs26) was confirmed using trap plasmids.

  16. Coexistence of mitochondrial 12S rRNA C1494T and CO1/tRNASer(UCN) G7444A mutations in two Han Chinese pedigrees with aminoglycoside-induced and non-syndromic hearing loss

    International Nuclear Information System (INIS)

    Yuan Huijun; Chen Jing; Liu Xin; Cheng Jing; Wang Xinjian; Yang Li; Yang Shuzhi; Cao Juyang; Kang Dongyang; Dai Pu; Zha, Suoqiang; Han Dongyi; Young Wieyen; Guan Minxin

    2007-01-01

    Mutations in mitochondrial DNA are one of the important causes of hearing loss. We report here the clinical, genetic, and molecular characterization of two Han Chinese pedigrees with maternally transmitted aminoglycoside-induced and nonsyndromic bilateral hearing loss. Clinical evaluation revealed the wide range of severity, age-at-onset, and audiometric configuration of hearing impairment in matrilineal relatives in these families. The penetrances of hearing loss in these pedigrees were 20% and 18%, when aminoglycoside-induced deafness was included. When the effect of aminoglycosides was excluded, the penetrances of hearing loss in these seven pedigrees were 10% and 15%. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the presence of the deafness-associated 12S rRNA C1494T and CO1/tRNA Ser(UCN) G7444A mutations. Their distinct sets of mtDNA polymorphism belonged to Eastern Asian haplogroup C4a1, while other previously identified six Chinese mitochondrial genomes harboring the C1494T mutation belong to haplogroups D5a2, D, R, and F1, respectively. This suggested that the C1494T or G7444A mutation occurred sporadically and multiplied through evolution of the mitochondrial DNA (mtDNA). The absence of functionally significant mutations in tRNA and rRNAs or secondary LHON mutations in their mtDNA suggest that these mtDNA haplogroup-specific variants may not play an important role in the phenotypic expression of the 12S rRNA C1494T and CO1/tRNA Ser(UCN) G7444A mutations in those Chinese families. However, aminoglycosides and other nuclear modifier genes play a modifying role in the phenotypic manifestation of the C1494T mutation in these Chinese families

  17. Detection of meca gene from methicillin resistant staphylococcus aureus isolates of north sumatera

    Science.gov (United States)

    Septiani Nasution, Gabriella; Suryanto, Dwi; Lia Kusumawati, R.

    2018-03-01

    Methicillin Resistant Staphylococcus aureus (MRSA) is a major pathogen associated with hospital-acquired infections (nosocomial infections). MRSA is a type of S. aureus resistant to the sub-group of beta-lactam antibiotics such as penicillin, cephalosporin, monobactam, and carbapenem. MRSA is resistant because of genetic changes caused by exposure to irrational antibiotic therapy. This study aimed to detect mecA gene in North Sumatra isolates of MRSA and to determine the pattern of antibiotic resistance in S.aureus isolates classified as MRSA by Vitek 2 Compact in the Central Public Hospital Haji Adam Malik, Medan. Samples were 40 isolates of S. aureus classified as MRSA obtained from clinical microbiology specimens. DNA isolation of the isolates was conducted by a method of freeze-thaw cycling. Amplification of mecA gene was done by PCR technique using specific primer for the gene. PCR products were visualized using mini-gel electrophoresis. The results showed that all MRSA isolates showed to have 533 bp band of mecA. Antibiotics test of Vitek 2 Compact showed that despite all isolates were resistant to beta-lactam antibiotics groups; the isolates showed multidrug resistant to other common antibiotics, such as aminoglycosides, macrolides, and fluoroquinolones. However, they were still sensitive to vancomycin (82.5% isolates), linezolid (97.5% isolates), and tigecycline (100% isolates).

  18. Antibiotic resistance determinants in a Pseudomonas putida strain isolated from a hospital.

    Directory of Open Access Journals (Sweden)

    Lázaro Molina

    Full Text Available Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267 kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts.

  19. Enterobacteriaceae in gut of honey bee (Apis mellifera and the antibiotic resistance of the isolates

    Directory of Open Access Journals (Sweden)

    Jaroslav Gasper

    2017-11-01

    Full Text Available Bacterial species of Enterobacteriaceae and the antimicrobial resistance of the isolates were detected in Apis mellifera L. bees gut. Gut content was cultivated on Meat peptone and McConkey agars at 30 and 37 °C, then, the isolates were identified with MALDI TOF MS Biotyper. Isolated strains were tested for antibiotic resistance to penicillins, cephalosporins, carbapenems, fluoroquinolones and aminoglycosides. Altogether, 12 species representing Enterobacteriaceae family were isolated. Firmicutes and Candida  were represented by Bacillus megaterium and Issatchenkia orientalis  . Isolated Enterobacteriaceae  species were  Enterobacter cloacae, Hafnia alvei, Klebsiella oxytoca, Morganella morganii, Serratia marcescens, Ser. liquefaciens, Raoultella ornithinolytica, R. planticola, R. terrigena, Pantoea ananatis, P. agglomerans, Rahnella aquatilis. Enterobacter cloacae, Hafnia alvei, Klebsiella oxytoca, Morganella morganii, Serratia marcescens, Ser. liquefaciens isolates exhibited the antimicrobial resistance more frequently than Raoultella ornithinolytica, R. planticola, R. terrigena, Pantoea ananatis, P. agglomerans, Rahnella aquatilis. Microflora of gut of bees could serve as a source of resistant microorganisms.

  20. Cryptic chromosome 9q34 deletion generates TAF-Ialpha/CAN and TAF-Ibeta/CAN fusion transcripts in acute myeloid leukemia.

    Science.gov (United States)

    Rosati, Roberto; La Starza, Roberta; Barba, Gianluca; Gorello, Paolo; Pierini, Valentina; Matteucci, Caterina; Roti, Giovanni; Crescenzi, Barbara; Aloisi, Teresa; Aversa, Franco; Martelli, Massimo Fabrizio; Mecucci, Cristina

    2007-02-01

    In hematologic malignancies chromosome aberrations generating fusion genes include cryptic deletions. In a patient with acute myeloid leukemia and normal karyo-type we discovered a new cryptic 9q34 deletion and here report the cytogenetic and molecular findings. The 9q34 deletion extends 2.5 megabases and juxtaposes the 5' TAF-I to the 3' CAN producing a TAF-I/CAN fusion gene. TAF-I/CAN transcribes into two fusion proteins bearing either TAF-Ialpha or TAF-Ibeta moieties. We set up molecular assays to monitor the chimeric TAF-Ialpha/CAN and TAF-Ibeta/CAN transcripts which, after hematopoietic stem cell transplantation from an HLA-identical sibling, were no longer detected.

  1. Quantitative Genetics Identifies Cryptic Genetic Variation Involved in the Paternal Regulation of Seed Development.

    Directory of Open Access Journals (Sweden)

    Nuno D Pires

    2016-01-01

    Full Text Available Embryonic development requires a correct balancing of maternal and paternal genetic information. This balance is mediated by genomic imprinting, an epigenetic mechanism that leads to parent-of-origin-dependent gene expression. The parental conflict (or kinship theory proposes that imprinting can evolve due to a conflict between maternal and paternal alleles over resource allocation during seed development. One assumption of this theory is that paternal alleles can regulate seed growth; however, paternal effects on seed size are often very low or non-existent. We demonstrate that there is a pool of cryptic genetic variation in the paternal control of Arabidopsis thaliana seed development. Such cryptic variation can be exposed in seeds that maternally inherit a medea mutation, suggesting that MEA acts as a maternal buffer of paternal effects. Genetic mapping using recombinant inbred lines, and a novel method for the mapping of parent-of-origin effects using whole-genome sequencing of segregant bulks, indicate that there are at least six loci with small, paternal effects on seed development. Together, our analyses reveal the existence of a pool of hidden genetic variation on the paternal control of seed development that is likely shaped by parental conflict.

  2. Cryptic Genetic Variation in Evolutionary Developmental Genetics

    Directory of Open Access Journals (Sweden)

    Annalise B. Paaby

    2016-06-01

    Full Text Available Evolutionary developmental genetics has traditionally been conducted by two groups: Molecular evolutionists who emphasize divergence between species or higher taxa, and quantitative geneticists who study variation within species. Neither approach really comes to grips with the complexities of evolutionary transitions, particularly in light of the realization from genome-wide association studies that most complex traits fit an infinitesimal architecture, being influenced by thousands of loci. This paper discusses robustness, plasticity and lability, phenomena that we argue potentiate major evolutionary changes and provide a bridge between the conceptual treatments of macro- and micro-evolution. We offer cryptic genetic variation and conditional neutrality as mechanisms by which standing genetic variation can lead to developmental system drift and, sheltered within canalized processes, may facilitate developmental transitions and the evolution of novelty. Synthesis of the two dominant perspectives will require recognition that adaptation, divergence, drift and stability all depend on similar underlying quantitative genetic processes—processes that cannot be fully observed in continuously varying visible traits.

  3. Resistant gram-negative bacilli and antibiotic consumption in zarqa, jordan

    International Nuclear Information System (INIS)

    Bataineh, H.A.; Alrashed, K.M.

    2007-01-01

    To investigate the prevalence of antibiotic resistance among gram-negative bacteria in relation to antibiotic use in Prince Hashem Hospital (PHH), Jordan. One hundred consecutive gram-negative bacterial isolates from different sites were collected from patients admitted to the ICU at PHH. The susceptibilities of the strains to 12 antibiotics were performed and interpreted. The quantities and the numbers of the patients discharged on antibiotics and the quantities consumed were obtained from the hospital pharmacy records. The most common isolate was P. aeruginosa (n=21) The most common site of isolation was the respiratory tract (65%), The highest susceptibility was to piperacillin/ tazobactam(78%), and the lowest was to cefuroxime(34%). The aminoglycosides gentamicin and amikacin were active against 71% and 73% of the isolates respectively, Ciprofloxacin was active against 75% of the isolates. The most frequently used antibiotics were the third-generation cephalosporins ceftriaxone and ceftazidime, followed by imipenem and amikacin. Antibiotic resistance surveillance programs associated with registration of antibiotic consumption are necessary to promote optimal use of antibiotics. Rational prescribing of antibiotics should be encouraged through educational programs, surveillance and audit. Proper infection control measures should be practiced to prevent horizontal transfer of drug-resistant organisms. (author)

  4. How to deal with cryptic species in Enchytraeidae, with recommendations on taxonomical descriptions

    Directory of Open Access Journals (Sweden)

    Schmelz, R. M.

    2017-11-01

    Full Text Available During the 12th International Symposium on Enchytraeidae, held in Tihany, Hungary (27–29 June 2016, the participants discussed cryptic species, i.e., species that are morphologically so similar that they are classified as the same species (Bickford et al. 2007, and how to deal with them taxonomically. Here we summarise the discussion together with a few additional comments, and we give recommendations for species descriptions in Enchytraeidae.

  5. The Novel Kasugamycin 2′-N-Acetyltransferase Gene aac(2′)-IIa, Carried by the IncP Island, Confers Kasugamycin Resistance to Rice-Pathogenic Bacteria

    OpenAIRE

    Yoshii, Atsushi; Moriyama, Hiromitsu; Fukuhara, Toshiyuki

    2012-01-01

    Kasugamycin (KSM), a unique aminoglycoside antibiotic, has been used in agriculture for many years to control not only rice blast caused by the fungus Magnaporthe grisea but also rice bacterial grain and seedling rot or rice bacterial brown stripe caused by Burkholderia glumae or Acidovorax avenae subsp. avenae, respectively. Since both bacterial pathogens are seed-borne and cause serious injury to rice seedlings, the emergence of KSM-resistant B. glumae and A. avenae isolates highlights the ...

  6. Extended-Spectrum-Beta-Lactamases, AmpC Beta-Lactamases and Plasmid Mediated Quinolone Resistance in Klebsiella spp. from Companion Animals in Italy

    DEFF Research Database (Denmark)

    Donati, Valentina; Feltrin, Fabiola; Hendriksen, Rene S.

    2014-01-01

    also for the aac(6')-Ib-cr gene. All Klebsiella isolates showed multiresistance towards aminoglycosides, sulfonamides, tetracyclines, trimethoprim and amphenicols, mediated by strA/B, aadA2, aadB, ant (2")-Ia, aac(6')-Ib, sul, tet, dfr and cat genes in various combinations. The emergence in pets...... of multidrug-resistant Klebsiella with ESBL, AmpC and PMQR determinants, poses further and serious challenges in companion animal therapy and raise concerns for possible bidirectional transmission between pets and humans, especially at household level....

  7. Distinct effects of struvite and biochar amendment on the class 1 integron antibiotic resistance gene cassettes in phyllosphere and rhizosphere.

    Science.gov (United States)

    An, Xin-Li; Chen, Qing-Lin; Zhu, Dong; Su, Jian-Qiang

    2018-08-01

    Struvite recovered from wastewater is promising for recycling phosphorus into soil as fertilizers. However, struvite application may prompt the proliferation of antibiotic resistance in soil and plant. This study examined the impacts of struvite application and biochar amendment on integrons abundance and gene cassette contexts in rhizosphere soil and phyllosphere using quantitative PCR and clone library analysis. Microcosm experiments revealed that class 1 integron was the most prevalent in all samples, with higher concentration and higher relative abundance in rhizosphere than those in phyllosphere. The majority of resistance gene cassettes were associated with genes encoding resistance to aminoglycosides, beta-lactams and chloramphenicols. Struvite application significantly increased the genetic diversity of antibiotic resistance gene cassettes in both rhizosphere and phyllosphere. However, biochar amendment attenuated the increasing effect of struvite application exerting on the class 1 integron antibiotic resistance gene cassette pool in phyllosphere. These findings highlighted human activities to be the source of integron gene cassette pool and raised the possibility of using biochar amendment as an alternative mean for mitigating antibiotic resistance in environments. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Identification of a cryptic prokaryotic promoter within the cDNA encoding the 5' end of dengue virus RNA genome.

    Directory of Open Access Journals (Sweden)

    Dongsheng Li

    Full Text Available Infectious cDNA clones of RNA viruses are important research tools, but flavivirus cDNA clones have proven difficult to assemble and propagate in bacteria. This has been attributed to genetic instability and/or host cell toxicity, however the mechanism leading to these difficulties has not been fully elucidated. Here we identify and characterize an efficient cryptic bacterial promoter in the cDNA encoding the dengue virus (DENV 5' UTR. Following cryptic transcription in E. coli, protein expression initiated at a conserved in-frame AUG that is downstream from the authentic DENV initiation codon, yielding a DENV polyprotein fragment that was truncated at the N-terminus. A more complete understanding of constitutive viral protein expression in E. coli might help explain the cloning and propagation difficulties generally observed with flavivirus cDNA.

  9. Complete genome sequence of multidrug-resistant Staphylococcus cohnii ssp. urealyticus strain SNUDS-2 isolated from farmed duck, Republic of Korea.

    Science.gov (United States)

    Han, Jee Eun; Lee, Seungki; Jeong, Dae Gwin; Yoon, Sun-Woo; Kim, Doo-Jin; Lee, Moo-Seung; Kim, Hye Kwon; Park, Sung-Kyun; Kim, Ji Hyung; Park, Se Chang

    2017-09-01

    Staphylococcus cohnii has become increasingly recognized as a potential pathogen of clinically significant nosocomial and farm animal infections. This study was designed to determine the genome of a multidrug-resistant S. cohnii subsp. urealyticus strain SNUDS-2 isolated from a farmed duck in Korea. Genomic DNA was sequenced using the PacBio RS II system. The complete genome was annotated and the presence of antimicrobial resistance and virulence genes were identified. The annotated 2,625,703 bp genome contained various antimicrobial resistance genes conferring resistance to β-lactam, aminoglycosides, fluoroquinolones, phenicols and trimethoprim. The virulence-associated three synergistic hemolysins have been identified in the strain. To the best of our knowledge, this is the first complete genome of S. cohnii, and will provide important insights into the biodiversity of CoNS and valuable information for the control of this emerging pathogen. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  10. Resolution of three cryptic agricultural pests (Ceratitis fasciventris, C. anonae, C. rosa, Diptera: Tephritidae) using cuticular hydrocarbon profiling

    Czech Academy of Sciences Publication Activity Database

    Vaníčková, Lucie; Virgilio, M.; Tomčala, Aleš; Břízová, Radka; Ekesi, S.; Hoskovec, Michal; Kalinová, Blanka; do Nascimento, R. R.; De Meyer, M.

    2014-01-01

    Roč. 104, č. 5 (2014), s. 631-638 ISSN 0007-4853 Institutional support: RVO:61388963 Keywords : cryptic species complex * genus Ceratitis * cuticular hydrocarbons * polymorphic microsatellite loci * chemotaxonomy Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.910, year: 2014

  11. Differential responses of cryptic bat species to the urban landscape.

    Science.gov (United States)

    Lintott, Paul R; Barlow, Kate; Bunnefeld, Nils; Briggs, Philip; Gajas Roig, Clara; Park, Kirsty J

    2016-04-01

    Urbanization is a key global driver in the modification of land use and has been linked to population declines even in widespread and relatively common species. Cities comprise a complex assortment of habitat types yet we know relatively little about the effects of their composition and spatial configuration on species distribution. Although many bat species exploit human resources, the majority of species are negatively impacted by urbanization. Here, we use data from the National Bat Monitoring Programme, a long-running citizen science scheme, to assess how two cryptic European bat species respond to the urban landscape. A total of 124 × 1 km(2) sites throughout Britain were surveyed. The landscape surrounding each site was mapped and classified into discrete biotope types (e.g., woodland). Generalized linear models were used to assess differences in the response to the urban environment between the two species, and which landscape factors were associated with the distributions of P. pipistrellus and P. pygmaeus. The relative prevalence of P. pygmaeus compared to P. pipistrellus was greater in urban landscapes with a higher density of rivers and lakes, whereas P. pipistrellus was frequently detected in landscapes comprising a high proportion of green space (e.g., parklands). Although P. pipistrellus is thought to be well adapted to the urban landscape, we found a strong negative response to urbanization at a relatively local scale (1 km), whilst P. pygmaeus was detected more regularly in wooded urban landscapes containing freshwater. These results show differential habitat use at a landscape scale of two morphologically similar species, indicating that cryptic species may respond differently to anthropogenic disturbance. Even species considered relatively common and well adapted to the urban landscape may respond negatively to the built environment highlighting the future challenges involved in maintaining biodiversity within an increasingly urbanized

  12. d-Tubocurarine and Berbamine: Alkaloids That Are Permeant Blockers of the Hair Cell's Mechano-Electrical Transducer Channel and Protect from Aminoglycoside Toxicity

    Directory of Open Access Journals (Sweden)

    Nerissa K. Kirkwood

    2017-09-01

    Full Text Available Aminoglycoside antibiotics are widely used for the treatment of life-threatening bacterial infections, but cause permanent hearing loss in a substantial proportion of treated patients. The sensory hair cells of the inner ear are damaged following entry of these antibiotics via the mechano-electrical transducer (MET channels located at the tips of the hair cell's stereocilia. d-Tubocurarine (dTC is a MET channel blocker that reduces the loading of gentamicin-Texas Red (GTTR into rat cochlear hair cells and protects them from gentamicin treatment. Berbamine is a structurally related alkaloid that reduces GTTR labeling of zebrafish lateral-line hair cells and protects them from aminoglycoside-induced cell death. Both compounds are thought to reduce aminoglycoside entry into hair cells through the MET channels. Here we show that dTC (≥6.25 μM or berbamine (≥1.55 μM protect zebrafish hair cells in vivo from neomycin (6.25 μM, 1 h. Protection of zebrafish hair cells against gentamicin (10 μM, 6 h was provided by ≥25 μM dTC or ≥12.5 μM berbamine. Hair cells in mouse cochlear cultures are protected from longer-term exposure to gentamicin (5 μM, 48 h by 20 μM berbamine or 25 μM dTC. Berbamine is, however, highly toxic to mouse cochlear hair cells at higher concentrations (≥30 μM whilst dTC is not. The absence of toxicity in the zebrafish assays prompts caution in extrapolating results from zebrafish neuromasts to mammalian cochlear hair cells. MET current recordings from mouse outer hair cells (OHCs show that both compounds are permeant open-channel blockers, rapidly and reversibly blocking the MET channel with half-blocking concentrations of 2.2 μM (dTC and 2.8 μM (berbamine in the presence of 1.3 mM Ca2+ at −104 mV. Berbamine, but not dTC, also blocks the hair cell's basolateral K+ current, IK,neo, and modeling studies indicate that berbamine permeates the MET channel more readily than dTC. These studies reveal key properties of

  13. The antibiotic resistance "mobilome": searching for the link between environment and clinic.

    Science.gov (United States)

    Perry, Julie A; Wright, Gerard D

    2013-01-01

    Antibiotic resistance is an ancient problem, owing to the co-evolution of antibiotic-producing and target organisms in the soil and other environments over millennia. The environmental "resistome" is the collection of all genes that directly or indirectly contribute to antibiotic resistance. Many of these resistance determinants originate in antibiotic-producing organisms (where they serve to mediate self-immunity), while others become resistance determinants only when mobilized and over-expressed in non-native hosts (like plasmid-encoded β-lactamases). The modern environmental resistome is under selective pressure from human activities such as agriculture, which may influence the composition of the local resistome and lead to gene transfer events. Beyond the environment, we are challenged in the clinic by the rise in both frequency and diversity of antibiotic resistant pathogens. We assume that clinical resistance originated in the environment, but few examples of direct gene exchange between the environmental resistome and the clinical resistome have been documented. Strong evidence exists to suggest that clinical aminoglycoside and vancomycin resistance enzymes, the extended-spectrum β-lactamase CTX-M and the quinolone resistance gene qnr have direct links to the environmental resistome. In this review, we highlight recent advances in our understanding of horizontal gene transfer of antibiotic resistance genes from the environment to the clinic. Improvements in sequencing technologies coupled with functional metagenomic studies have revealed previously underappreciated diversity in the environmental resistome, and also established novel genetic links to the clinic. Understanding mechanisms of gene exchange becomes vital in controlling the future dissemination of antibiotic resistance.

  14. Synthesis and antibacterial activity of 1-N-(1,3-dihydroxy-2-propyl)kanamycin B (UK-31,214).

    Science.gov (United States)

    Richardson, K; Brammer, K W; Jevons, S; Plews, R M; Wright, J R

    1979-10-01

    1-N-(1,3-Dihydroxy-2-propyl)kanamycin B was prepared and its in vitro activity against aminoglycoside-sensitive and aminoglycoside-resistant organisms was compared with that of kanamycin B and gentamicin. This kanamycin B derivative (code No. UK-31,214) demonstrated potent activity in all of these tests and gave good protection in experimental infections in mice.

  15. Synthesis and antibacterial activities of 1-N [(S)-omega-amino-2-hydroxyalkyl] kanamycin A derivatives.

    Science.gov (United States)

    Richardson, K; Jevons, S; Moore, J W; Ross, B C; Wright, J R

    1977-10-01

    Four 1-N-aminohydroxy-alkyl derivatives of kanamycin A were prepared and their in vitro activities against aminoglycoside-sensitive and aminoglycoside-resistant organisms were compared with amikacin. 1-N-[(S)-4-Amino-2-hydroxybutyl] kanamycin A (Fig. 1, compound 2, code no. UK-18,892) was equipotent to amikacin in all these tests and in mouse protection studies.

  16. An analysis of species boundaries and biogeographic patterns in a cryptic species complex: the rotifer--Brachionus plicatilis.

    Science.gov (United States)

    Suatoni, Elizabeth; Vicario, Saverio; Rice, Sean; Snell, Terry; Caccone, Adalgisa

    2006-10-01

    Since the advent of molecular phylogenetics, there is increasing evidence that many small aquatic and marine invertebrates--once believed to be single, cosmopolitan species--are in fact cryptic species complexes. Although the application of the biological species concept is central to the identification of species boundaries in these cryptic complexes, tests of reproductive isolation do not frequently accompany phylogenetic studies. Because different species concepts generally identify different boundaries in cryptic complexes, studies that apply multiple species concepts are needed to gain a more detailed understanding of patterns of diversification in these taxa. Here we explore different methods of empirically delimiting species boundaries in the salt water rotifer Brachionus plicatilis by comparing reproductive data (i.e., the traditional biological species concept) to phylogenetic data (the genealogical species concept). Based on a high degree of molecular sequence divergence and largely concordant genetic patterns in COI and ITS1, the genealogical species hypothesis indicates the existence of at least 14 species--the highest estimate for the group thus far. A test of the genealogical species concept with biological crosses shows a fairly high level of concordance, depending on the degree of reproductive success used to draw boundaries. The convergence of species concepts in this group suggests that many of the species within the group may be old. Although the diversity of the group is higher than previously understood, geographic distributions remain broad. Efficient passive dispersal has resulted in global distributions for many species with some evidence of isolation by distance over large geographic scales. These patterns concur with expectations that micro-meiofauna (0.1-1mm) have biogeographies intermediate to microbial organisms and large vertebrates. Sympatry of genetically distant strains is common.

  17. Botrytis californica, a new cryptic species in the B. cinerea species complex causing gray mold in blueberries and table grapes.

    Science.gov (United States)

    Saito, S; Margosan, D; Michailides, T J; Xiao, C L

    2016-01-01

    The Botrytis cinerea species complex comprises two cryptic species, originally referred to Group I and Group II based on Bc-hch gene RFLP haplotyping. Group I was described as a new cryptic species B. pseudocinerea During a survey of Botrytis spp. causing gray mold in blueberries and table grapes in the Central Valley of California, six isolates, three from blueberries and three from table grapes, were placed in Group I but had a distinct morphological character with conidiophores significantly longer than those of B. cinerea and B. pseudocinerea We compared these with B. cinerea and B. pseudocinerea by examining morphological and physiological characters, sensitivity to fenhexamid and phylogenetic analysis inferred from sequences of three nuclear genes. Phylogenetic analysis with the three partial gene sequences encoding glyceraldehyde-3-phosate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60) and DNA-dependent RNA polymerase subunit II (RPB2) supported the proposal of a new Botrytis species, B. californica, which is closely related genetically to B. cinerea, B. pseudocinerea and B. sinoviticola, all known as causal agents of gray mold of grapes. Botrytis californica caused decay on blueberry and table grape fruit inoculated with the fungus. This study suggests that B. californica is a cryptic species sympatric with B. cinerea on blueberries and table grapes in California. © 2016 by The Mycological Society of America.

  18. Rapid detection of drug resistance and mutational patterns of extensively drug-resistant strains by a novel GenoType® MTBDRsl assay

    Directory of Open Access Journals (Sweden)

    A K Singh

    2013-01-01

    Full Text Available Background: The emergence of extensively drug-resistant tuberculosis (XDR-TB is a major concern in the India. The burden of XDR-TB is increasing due to inadequate monitoring, lack of proper diagnosis, and treatment. The GenoType ® Mycobacterium tuberculosis drug resistance second line (MTBDRsl assay is a novel line probe assay used for the rapid detection of mutational patterns conferring resistance to XDR-TB. Aim: The aim of this study was to study the rapid detection of drug resistance and mutational patterns of the XDR-TB by a novel GenoType ® MTBDRsl assay. Materials and Methods: We evaluated 98 multidrug-resistant (MDR M. tuberculosis isolates for second line drugs susceptibility testing by 1% proportion method (BacT/ALERT 3D system and GenoType ® MTBDRsl assay for rapid detection of conferring drug resistance to XDR-TB. Results: A total of seven (17.4% were identified as XDR-TB by using standard phenotypic method. The concordance between phenotypic and GenoType ® MTBDRsl assay was 91.7-100% for different antibiotics. The sensitivity and specificity of the MTBDRsl assay were 100% and 100% for aminoglycosides; 100% and 100% for fluoroquinolones; 91.7% and 100% for ethambutol. The most frequent mutations and patterns were gyrA MUT1 (A90V in seven (41.2% and gyrA + WT1-3 + MUT1 in four (23.5%; rrs MUT1 (A1401G in 11 (64.7%, and rrs WT1-2 + MUT1 in eight (47.1%; and embB MUT1B (M306V in 11 (64.7% strains. Conclusions: These data suggest that the GenoType ® MTBDRsl assay is rapid, novel test for detection of resistance to second line anti-tubercular drugs. This assay provides additional information about the frequency and mutational patterns responsible for XDR-TB resistance.

  19. Cryptically patterned moths perceive bark structure when choosing body orientations that match wing color pattern to the bark pattern.

    Science.gov (United States)

    Kang, Chang-Ku; Moon, Jong-Yeol; Lee, Sang-Im; Jablonski, Piotr G

    2013-01-01

    Many moths have wing patterns that resemble bark of trees on which they rest. The wing patterns help moths to become camouflaged and to avoid predation because the moths are able to assume specific body orientations that produce a very good match between the pattern on the bark and the pattern on the wings. Furthermore, after landing on a bark moths are able to perceive stimuli that correlate with their crypticity and are able to re-position their bodies to new more cryptic locations and body orientations. However, the proximate mechanisms, i.e. how a moth finds an appropriate resting position and orientation, are poorly studied. Here, we used a geometrid moth Jankowskia fuscaria to examine i) whether a choice of resting orientation by moths depends on the properties of natural background, and ii) what sensory cues moths use. We studied moths' behavior on natural (a tree log) and artificial backgrounds, each of which was designed to mimic one of the hypothetical cues that moths may perceive on a tree trunk (visual pattern, directional furrow structure, and curvature). We found that moths mainly used structural cues from the background when choosing their resting position and orientation. Our findings highlight the possibility that moths use information from one type of sensory modality (structure of furrows is probably detected through tactile channel) to achieve crypticity in another sensory modality (visual). This study extends our knowledge of how behavior, sensory systems and morphology of animals interact to produce crypsis.

  20. Markov Networks of Collateral Resistance: National Antimicrobial Resistance Monitoring System Surveillance Results from Escherichia coli Isolates, 2004-2012.

    Directory of Open Access Journals (Sweden)

    William J Love

    2016-11-01

    Full Text Available Surveillance of antimicrobial resistance (AMR is an important component of public health. Antimicrobial drug use generates selective pressure that may lead to resistance against to the administered drug, and may also select for collateral resistances to other drugs. Analysis of AMR surveillance data has focused on resistance to individual drugs but joint distributions of resistance in bacterial populations are infrequently analyzed and reported. New methods are needed to characterize and communicate joint resistance distributions. Markov networks are a class of graphical models that define connections, or edges, between pairs of variables with non-zero partial correlations and are used here to describe AMR resistance relationships. The graphical least absolute shrinkage and selection operator is used to estimate sparse Markov networks from AMR surveillance data. The method is demonstrated using a subset of Escherichia coli isolates collected by the National Antimicrobial Resistance Monitoring System between 2004 and 2012 which included AMR results for 16 drugs from 14418 isolates. Of the 119 possible unique edges, 33 unique edges were identified at least once during the study period and graphical density ranged from 16.2% to 24.8%. Two frequent dense subgraphs were noted, one containing the five β-lactam drugs and the other containing both sulfonamides, three aminoglycosides, and tetracycline. Density did not appear to change over time (p = 0.71. Unweighted modularity did not appear to change over time (p = 0.18, but a significant decreasing trend was noted in the modularity of the weighted networks (p < 0.005 indicating relationships between drugs of different classes tended to increase in strength and frequency over time compared to relationships between drugs of the same class. The current method provides a novel method to study the joint resistance distribution, but additional work is required to unite the underlying biological and genetic

  1. Cryptic species of Ponto-Caspian bighead goby of the genus Ponticola (Gobiidae)

    DEFF Research Database (Denmark)

    Vasil'eva, E. D.; Schwarzhans, Werner; Medvedev, D. A.

    2016-01-01

    . gorlap which inhabits the northern, western, and southern Caspian Sea. These three allopatric species have ctenoid scales to varying degrees on the crown and nape (100% presence in P. kessleri and complete absence in P. iljini), and there are small differences in the shape of the head, the thickness...... of the beginning of divergence of the considered three cryptic species, as well as isolating barriers that led to allopatric speciation, are discussed....

  2. Whole genome sequencing for the molecular characterization of carbapenem-resistant Klebsiella pneumoniae strains isolated at the Italian ASST Fatebenefratelli Sacco Hospital, 2012-2014.

    Science.gov (United States)

    Rimoldi, Sara Giordana; Gentile, Bernardina; Pagani, Cristina; Di Gregorio, Annamaria; Anselmo, Anna; Palozzi, Anna Maria; Fortunato, Antonella; Pittiglio, Valentina; Ridolfo, Anna Lisa; Gismondo, Maria Rita; Rizzardini, Giuliano; Lista, Florigio

    2017-10-10

    The emergence of carbapenem-resistant Klebsiella pneumoniae strains is threatening antimicrobial treatment. Sixty-eight carbapenemase-producing K. pneumoniae strains isolated at Luigi Sacco University Hospital-ASST Fatebenefratelli Sacco (Milan, Italy) between 2012 and 2014 were characterised microbiologically and molecularly. They were tested for drug susceptibility and carbapenemase phenotypes, investigated by means of repetitive extra-genic palindromic polymerase chain reaction (REP-PCR), and fully sequenced by means of next-generation sequencing for the in silico analysis of multi-locus sequence typing (MLST), their resistome, virulome and plasmid content, and their core single nucleotide polymorphism (SNP) genotypes. All of the samples were resistant to carbapenems, other β-lactams and ciprofloxacin; many were resistant to aminoglycosides and tigecycline; and seven were resistant to colistin. Resistome analysis revealed the presence of blaKPC genes and, less frequently blaSHV, blaTEM, blaCTX-M and blaOXA, which are related to resistance to carbapenem and other β-lactams. Other genes conferring resistance to aminoglycoside, fluoroquinolone, phenicol, sulphonamide, tetracycline, trimethoprim and macrolide-lincosamide-streptogramin were also detected. Genes related to AcrAB-TolC efflux pump-dependent and pump-independent tigecycline resistance mechanisms were investigated, but it was not possible to clearly correlate the genomic features with tigecycline resistance because of the presence of a common mutation in susceptible, intermediate and resistant strains. Concerning colistin resistance, the mgrB gene was disrupted by an IS5-like element, and the mobile mcr-1 and mcr-2 genes were not detected in two cases. The virulome profile revealed type-3 fimbriae and iron uptake system genes, which are important during the colonisation stage in the mammalian host environment. The in silico detected plasmid replicons were classified as IncFIB(pQil), IncFIB(K), Col

  3. Environmental cycle of antibiotic resistance encoded genes: A systematic review

    Directory of Open Access Journals (Sweden)

    R. ghanbari

    2017-12-01

    Full Text Available Antibiotic-resistant bacteria and genes enter the environment in different ways. The release of these factors into the environment has increased concerns related to public health. The aim of the study was to evaluate the antibiotic resistance genes (ARGs in the environmental resources. In this systematic review, the data were extracted from valid sources of information including ScienceDirect, PubMed, Google Scholar and SID. Evaluation and selection of articles were conducted on the basis of the PRISMA checklist. A total of 39 articles were included in the study, which were chosen from a total of 1249 papers. The inclusion criterion was the identification of genes encoding antibiotic resistance against the eight important groups of antibiotics determined by using the PCR technique in the environmental sources including municipal and hospital wastewater treatment plants, animal and agricultural wastes, effluents from treatment plants, natural waters, sediments, and drinking waters. In this study, 113 genes encoding antibiotic resistance to eight groups of antibiotics (beta-lactams, aminoglycosides, tetracyclines, macrolides, sulfonamides, chloramphenicol, glycopeptides and quinolones were identified in various environments. Antibiotic resistance genes were found in all the investigated environments. The investigation of microorganisms carrying these genes shows that most of the bacteria especially gram-negative bacteria are effective in the acquisition and the dissemination of these pollutants in the environment. Discharging the raw wastewaters and effluents from wastewater treatments acts as major routes in the dissemination of ARGs into environment sources and can pose hazards to public health.

  4. The Antibiotic Resistance ‘Mobilome’: searching for the link between environment and clinic.

    Directory of Open Access Journals (Sweden)

    Julie ePerry

    2013-05-01

    Full Text Available Antibiotic resistance is an ancient problem, owing to the co-evolution of antibiotic-producing and target organisms in the soil and other environments over millennia. The environmental ‘resistome’ is the collection of all genes that directly or indirectly contribute to antibiotic resistance. Many of these resistance determinants originate in antibiotic-producing organisms (where they serve to mediate self-immunity, while others become resistance determinants only when mobilized and over-expressed in non-native hosts (like plasmid-based β-lactamases. The modern environmental resistome is under selective pressure from human activities such as agriculture, which may influence the composition of the local resistome and lead to gene transfer events. Beyond the environment, we are challenged in the clinic by the rise in both frequency and diversity of antibiotic resistant pathogens. We assume that clinical resistance originated in the environment, but few examples of direct gene exchange between the environmental resistome and the clinical resistome have been documented. Strong evidence exists to suggest that clinical aminoglycoside and vancomycin resistance enzymes, the extended-spectrum β-lactamase CTX-M and the quinolone resistance gene Qnr have direct links to the environmental resistome. In this review, we highlight recent advances in our understanding of horizontal gene transfer of antibiotic resistance genes from the environment to the clinic. Improvements in sequencing technologies coupled with functional metagenomic studies have revealed previously underappreciated diversity in the environmental resistome, and also established novel genetic links to the clinic. Understanding mechanisms of gene exchange becomes vital in controlling the future dissemination of antibiotic resistance.

  5. The antibiotic resistance “mobilome”: searching for the link between environment and clinic

    Science.gov (United States)

    Perry, Julie A.; Wright, Gerard D.

    2013-01-01

    Antibiotic resistance is an ancient problem, owing to the co-evolution of antibiotic-producing and target organisms in the soil and other environments over millennia. The environmental “resistome” is the collection of all genes that directly or indirectly contribute to antibiotic resistance. Many of these resistance determinants originate in antibiotic-producing organisms (where they serve to mediate self-immunity), while others become resistance determinants only when mobilized and over-expressed in non-native hosts (like plasmid-encoded β-lactamases). The modern environmental resistome is under selective pressure from human activities such as agriculture, which may influence the composition of the local resistome and lead to gene transfer events. Beyond the environment, we are challenged in the clinic by the rise in both frequency and diversity of antibiotic resistant pathogens. We assume that clinical resistance originated in the environment, but few examples of direct gene exchange between the environmental resistome and the clinical resistome have been documented. Strong evidence exists to suggest that clinical aminoglycoside and vancomycin resistance enzymes, the extended-spectrum β-lactamase CTX-M and the quinolone resistance gene qnr have direct links to the environmental resistome. In this review, we highlight recent advances in our understanding of horizontal gene transfer of antibiotic resistance genes from the environment to the clinic. Improvements in sequencing technologies coupled with functional metagenomic studies have revealed previously underappreciated diversity in the environmental resistome, and also established novel genetic links to the clinic. Understanding mechanisms of gene exchange becomes vital in controlling the future dissemination of antibiotic resistance. PMID:23755047

  6. Cryptic within cryptic: genetics, morphometrics, and bioacoustics delimitate a new species of Eleutherodactylus (Anura: Eleutherodactylidae) from Eastern Cuba.

    Science.gov (United States)

    Rodríguez, Ariel; Dugo-Cota, Álvaro; Montero-Mendieta, Santiago; Gonzalez-Voyer, Alejandro; Bosch, Roberto Alonso; Vences, Miguel; Vilà, Carles

    2017-01-20

    We studied the variation in genetics, bioacustics, and morphology in Eleutherodactylus glamyrus, a regionally endemic frog species restricted to high elevations in the Sierra Maestra Massif, Western Cuba that was originally described as a cryptic species hidden under the name E. auriculatus. Genetic analysis of mtDNA sequences of the 16S and cob genes identify two allopatric and strongly supported mitochondrial clades (phylogroups) which also showed no haplotype sharing in the nuclear Rag-1 gene. Bioacustic, and morphological comparisons concordantly identify these two phylogroups as independent evolutionary lineages. Therefore, we herein restrict the name Eleutherodactylus glamyrus Estrada and Hedges to populations represented in our analyses as the western phylogroup (Cordillera del Turquino to Pico La Bayamesa) and consider specimens from the eastern phylogroup (Sierra del Cobre) to represent a new species described and named as Eleutherodactylus cattus. Our results add to the growing list of Eleutherodactylus species endemic to Cuba and highlight the importance of combining different sources of evidence for obtaining robust assessments of species limits in amphibians.

  7. The sensitivity of Bacillus subtilis to diverse antimicrobial compounds is influenced by Abh.

    Science.gov (United States)

    Murray, Ewan J; Stanley-Wall, Nicola R

    2010-12-01

    Abh is a transition state regulator of Bacillus subtilis that controls biofilm formation and the production of several diverse antimicrobial compounds. Using a high-throughput non-biased technique, we show for the first time that Abh influences the sensitivity of B. subtilis to diverse antimicrobial compounds. Following up on these findings with a combination of classical genetics and antibiotic susceptibility assays, we demonstrate that Abh influences cellular processes such as the remodelling of the cell wall. We present data demonstrating that the extracytoplasmic function sigma factor σ(X) controls resistance to β-lactam antibiotics by activating abh transcription. Downstream from Abh, activation of slrR expression by Abh is responsible for controlling the sensitivity of B. subtilis to such antibiotics due to the role that SlrR plays in regulating autolysin biosynthesis. The abh mutant additionally exhibits increased resistance to aminoglycoside antimicrobials. We confirm that aminoglycoside killing of B. subtilis is likely to be caused by oxidative damage but rule out the possibility that the increased resistance of the abh mutant to aminoglycosides is due to a general increase in resistance to oxidative stress.

  8. Epidemiology of infections caused by multiresistant gram-negatives: ESBLs, MBLs, panresistant strains.

    Science.gov (United States)

    Rossolini, Gian Maria; Mantengoli, Elisabetta; Docquier, Jean-Denis; Musmanno, Rosa Anna; Coratza, Grazietta

    2007-07-01

    Microbial drug resistance is a growing problem of global magnitude. In gram-negative pathogens, the most important resistance problems are encountered in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter, with increasing trends observed for all major anti-gram-negative agents (beta-lactams, fluoroquinolones and aminoglycosides). A matter of major concern is the emergence of new beta-lactamases capable of degrading the expanded-spectrum cephalosporins and/or carbapenems, such as the extended-spectrum beta-lactamases (ESBLs) and the carbapenemases. These beta-lactamase genes are often associated with resistance determinants to non-beta-lactam agents (e.g. aminoglycosides and fluoroquinolones), and strains producing ESBLs or carbapenemases often exhibit complex multidrug resistant phenotypes and sometimes are panresistant. The problem is worsened by the dearth of new agents active on multidrug-resistant Gram-negatives in the pipeline. The importance to develop better strategies to control resistance is underscored.

  9. The frequency of resistance to antibiotics of most frequently isolated bacteria from blood cultures during the period 1997-2002

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    Mirović Veljko

    2004-01-01

    Full Text Available The aim of this study was to determine the frequency of resistance to antibiotics of the most frequently isolated bacteria from blood cultures of hospitalized patients during the period 1997-2002. The resistance to antibiotics was determined by disk diffusion method according to National Committee for Clinical Laboratory Standards procedures. The majority of staphylococci isolates were resistant to methicillin, and the proportion of methicillin-resistant Staphylococcus aureus was stable (76.8-81.6%, during the follow-up period. None of the staphylococci isolates were resistant to vancomycin, but there was a very high incidence of high-level resistance of enterococci to aminoglycosides (47.2-72.2%. In 1998, only one strain among enterococci was resistant to vancomycin (Enterococcus faecium, VanA fenotype. Enterococcus spp isolates expressed variable frequency of resistance to ampicillin (15-40.1% during the follow-up period. Among Enterobacteriaceae there were no isolates resistant to imipenem, but dramatic increase of the resistance to ceftriaxone was found from 35.9% in 1997 to 95.9% in 2002 (p<0.001. Extended spectrum beta-lactamases production was found in all the species of enterobacteria isolates. Resistance to imipenem was observed in Acinetobacter spp isolates in 2002 for the first time. Pseudomonas spp isolates expressed high and very variable resistance to all antibiotics tested during the follow-up period.

  10. Trend and seasonality of community-acquired Escherichia coli antimicrobial resistance and its dynamic relationship with antimicrobial use assessed by ARIMA models.

    Science.gov (United States)

    Asencio Egea, María Ángeles; Huertas Vaquero, María; Carranza González, Rafael; Herráez Carrera, Óscar; Redondo González, Olga; Arias Arias, Ángel

    2017-12-04

    We studied the trend and seasonality of community-acquired Escherichia coli resistance and quantified its correlation with the previous use of certain antibiotics. A time series study of resistant community-acquired E. coli isolates and their association with antibiotic use was conducted in a Primary Health Care Area from 2008 to 2012. A Poisson regression model was constructed to estimate the trend and seasonality of E. coli resistance. A significant increasing trend in mean E. coli resistance to cephalosporins, aminoglycosides and nitrofurantoin was observed. Seasonal resistance to ciprofloxacin and amoxicillin-clavulanic acid was significantly higher in autumn-winter. There was a delay of 7, 10 and 12 months between the use of cotrimoxazole (P<0.038), fosfomycin (P<0.024) and amoxicillin-clavulanic acid (P<0.015), respectively, and the occurrence of E. coli resistance. An average delay of 10 months between the previous use of amoxicillin-clavulanic acid, cotrimoxazole and fosfomycin and the appearance of resistant community-acquired E. coli strains was detected. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  11. Coalescent Modelling Suggests Recent Secondary-Contact of Cryptic Penguin Species.

    Science.gov (United States)

    Grosser, Stefanie; Burridge, Christopher P; Peucker, Amanda J; Waters, Jonathan M

    2015-01-01

    Molecular genetic analyses present powerful tools for elucidating demographic and biogeographic histories of taxa. Here we present genetic evidence showing a dynamic history for two cryptic lineages within Eudyptula, the world's smallest penguin. Specifically, we use a suite of genetic markers to reveal that two congeneric taxa ('Australia' and 'New Zealand') co-occur in southern New Zealand, with only low levels of hybridization. Coalescent modelling suggests that the Australian little penguin only recently expanded into southern New Zealand. Analyses conducted under time-dependent molecular evolutionary rates lend support to the hypothesis of recent anthropogenic turnover, consistent with shifts detected in several other New Zealand coastal vertebrate taxa. This apparent turnover event highlights the dynamic nature of the region's coastal ecosystem.

  12. Diversity of fecal coliforms and their antimicrobial resistance patterns in wastewater treatment model plant.

    Science.gov (United States)

    Luczkiewicz, A; Fudala-Ksiazek, S; Jankowska, K; Quant, B; Olańczuk-Neyman, K

    2010-01-01

    The occurrence of resistance patterns among wastewater fecal coliforms was determined in the study. Susceptibility of the isolates was tested against 19 antimicrobial agents: aminoglycosides, aztreonam, carbapenems, cephalosporines, beta-lactam/beta-lactamase inhibitors, penicillines, tetracycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. Additionally the removal of resistant isolates was evaluated in the laboratory-scale wastewater treatment model plant (M-WWTP), continuously supplied with the wastewater obtained from the full-scale WWTP. Number of fecal coliforms in raw (after mechanical treatment) and treated wastewater, as well as in aerobic chamber effluent was determined using selective medium. The selected strains were identified and examined for antibiotic resistance using Phoenix Automated Microbiology System (BD Biosciences, USA). The strains were identified as Escherichia coli (n=222), Klebsiella pneumoniae ssp. ozaenae (n=9), and Pantoea agglomerans (n=1). The isolate of P. agglomerans as well as 48% of E. coli isolates were sensitive to all antimicrobials tested. The most frequent resistance patterns were found for ampicillin: 100% of K. pneumoniae ssp. ozaenae and 41% of E. coli isolates. Among E. coli isolates 12% was regarded as multiple antimicrobial resistant (MAR). In the studied M-WWTP, the applied activated sludge processes reduced considerably the number of fecal coliforms, but increased the ratio of antimicrobial-resistant E. coli isolates to sensitive ones, especially among strains with MAR patterns.

  13. DNA barcoding reveals a cryptic nemertean invasion in Atlantic and Mediterranean waters

    Science.gov (United States)

    Fernández-Álvarez, Fernando Ángel; Machordom, Annie

    2013-09-01

    For several groups, like nemerteans, morphology-based identification is a hard discipline, but DNA barcoding may help non-experts in the identification process. In this study, DNA barcoding is used to reveal the cryptic invasion of Pacific Cephalothrix cf. simula into Atlantic and Mediterranean coasts. Although DNA barcoding is a promising method for the identification of Nemertea, only 6 % of the known number of nemertean species is currently associated with a correct DNA barcode. Therefore, additional morphological and molecular studies are necessary to advance the utility of DNA barcoding in the characterisation of possible nemertean alien invasions.

  14. Simultaneous analysis of aminoglycosides with many other classes of drug residues in bovine tissues by ultrahigh-performance liquid chromatography-tandem mass spectrometry using an ion-pairing reagent added to final extracts.

    Science.gov (United States)

    Lehotay, Steven J; Lightfield, Alan R

    2018-01-01

    The way to maximize scope of analysis, sample throughput, and laboratory efficiency in the monitoring of veterinary drug residues in food animals is to determine as many analytes as possible as fast as possible in as few methods as possible. Capital and overhead expenses are also reduced by using fewer instruments in the overall monitoring scheme. Traditionally, the highly polar aminoglycoside antibiotics require different chromatographic conditions from other classes of drugs, but in this work, we demonstrate that an ion-pairing reagent (sodium 1-heptanesulfonate) added to the combined final extracts from two sample preparation methods attains good separation of 174 targeted drugs, including 9 aminoglycosides, in the same 10.5-min ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The full method was validated in bovine kidney, liver, and muscle tissues according to US regulatory protocols, and 137-146 (79-84%) of the drugs gave between 70 and 120% average recoveries with ≤ 25% RSDs in the different types of tissues spiked at 0.5, 1, and 2 times the regulatory levels of interest (10-1000 ng/g depending on the drug). This method increases sample throughput and the possible number of drugs monitored in the US National Residue Program, and requires only one UHPLC-MS/MS method and instrument for analysis rather than two by the previous scheme. Graphical abstract Outline of the streamlined approach to monitor 174 veterinary drugs, including aminoglycosides, in bovine tissues by combining two extracts of the same sample with an ion-pairing reagent for analysis by UHPLC-MS/MS.

  15. Intronic L1 retrotransposons and nested genes cause transcriptional interference by inducing intron retention, exonization and cryptic polyadenylation.

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    Kristel Kaer

    Full Text Available Transcriptional interference has been recently recognized as an unexpectedly complex and mostly negative regulation of genes. Despite a relatively few studies that emerged in recent years, it has been demonstrated that a readthrough transcription derived from one gene can influence the transcription of another overlapping or nested gene. However, the molecular effects resulting from this interaction are largely unknown.Using in silico chromosome walking, we searched for prematurely terminated transcripts bearing signatures of intron retention or exonization of intronic sequence at their 3' ends upstream to human L1 retrotransposons, protein-coding and noncoding nested genes. We demonstrate that transcriptional interference induced by intronic L1s (or other repeated DNAs and nested genes could be characterized by intron retention, forced exonization and cryptic polyadenylation. These molecular effects were revealed from the analysis of endogenous transcripts derived from different cell lines and tissues and confirmed by the expression of three minigenes in cell culture. While intron retention and exonization were comparably observed in introns upstream to L1s, forced exonization was preferentially detected in nested genes. Transcriptional interference induced by L1 or nested genes was dependent on the presence or absence of cryptic splice sites, affected the inclusion or exclusion of the upstream exon and the use of cryptic polyadenylation signals.Our results suggest that transcriptional interference induced by intronic L1s and nested genes could influence the transcription of the large number of genes in normal as well as in tumor tissues. Therefore, this type of interference could have a major impact on the regulation of the host gene expression.

  16. Unique mitochondrial DNA lineages in Irish stickleback populations: cryptic refugium or rapid recolonization?

    Science.gov (United States)

    Ravinet, Mark; Harrod, Chris; Eizaguirre, Christophe; Prodöhl, Paulo A

    2014-06-01

    Repeated recolonization of freshwater environments following Pleistocene glaciations has played a major role in the evolution and adaptation of anadromous taxa. Located at the western fringe of Europe, Ireland and Britain were likely recolonized rapidly by anadromous fishes from the North Atlantic following the last glacial maximum (LGM). While the presence of unique mitochondrial haplotypes in Ireland suggests that a cryptic northern refugium may have played a role in recolonization, no explicit test of this hypothesis has been conducted. The three-spined stickleback is native and ubiquitous to aquatic ecosystems throughout Ireland, making it an excellent model species with which to examine the biogeographical history of anadromous fishes in the region. We used mitochondrial and microsatellite markers to examine the presence of divergent evolutionary lineages and to assess broad-scale patterns of geographical clustering among postglacially isolated populations. Our results confirm that Ireland is a region of secondary contact for divergent mitochondrial lineages and that endemic haplotypes occur in populations in Central and Southern Ireland. To test whether a putative Irish lineage arose from a cryptic Irish refugium, we used approximate Bayesian computation (ABC). However, we found no support for this hypothesis. Instead, the Irish lineage likely diverged from the European lineage as a result of postglacial isolation of freshwater populations by rising sea levels. These findings emphasize the need to rigorously test biogeographical hypothesis and contribute further evidence that postglacial processes may have shaped genetic diversity in temperate fauna.

  17. Hidden in plain view: Cryptic diversity in the emblematic Araucaria of New Caledonia.

    Science.gov (United States)

    Ruhsam, Markus; Clark, Alexandra; Finger, Aline; Wulff, Adrien S; Mill, Robert R; Thomas, Philip I; Gardner, Martin F; Gaudeul, Myriam; Ennos, Richard A; Hollingsworth, Peter M

    2016-05-01

    Cryptic species represent a conservation challenge, because distributions and threats cannot be accurately assessed until species are recognized and defined. Cryptic species are common in diminutive and morphologically simple organisms, but are rare in charismatic and/or highly visible groups such as conifers. New Caledonia, a small island in the southern Pacific is a hotspot of diversity for the emblematic conifer genus Araucaria (Araucariaceae, Monkey Puzzle trees) where 13 of the 19 recognized species are endemic. We sampled across the entire geographical distribution of two closely related species (Araucaria rulei and A. muelleri) and screened them for genetic variation at 12 nuclear and 14 plastid microsatellites and one plastid minisatellite; a subset of the samples was also examined using leaf morphometrics. The genetic data show that populations of the endangered A. muelleri fall into two clearly distinct genetic groups: one corresponding to montane populations, the other corresponding to trees from lower elevation populations from around the Goro plateau. These Goro plateau populations are more closely related to A. rulei, but are sufficiently genetically and morphological distinct to warrant recognition as a new species. Our study shows the presence of a previously unrecognized species in this flagship group, and that A. muelleri has 30% fewer individuals than previously thought. Combined, this clarification of species diversity and distributions provides important information to aid conservation planning for New Caledonian Araucaria. © 2016 Botanical Society of America.

  18. Comparative Study of Erythrocyte Sedimentation Rate after Aminoglycoside and Aminocyclitol Treatment in Goats (Capra hircus

    Directory of Open Access Journals (Sweden)

    Toncho DINEV

    2016-07-01

    Full Text Available The aim of the present study was to follow up the erythrocyte sedimentation rate (ESR in healthy female goats during and after 5-day parenteral treatment with amikacin (10 mg/kg, tobramycin (5 mg/kg, apramycin (20 mg/kg, gentamicin (4 mg/kg, kanamycin (10 mg/kg and spectinomycin (20 mg/kg. Gentamicin and tobramycin caused an initial increase followed by a significant decrease of ESR on the 5th day for gentamicin and the 10th day for tobramycin, respectively, followed by recovery after the treatment. Reversely, amikacin and especially spectinomycin produced an increase of ESR without recovery several days post treatment. Kanamycin caused decrease of ESR on the 5th day without recovery in the subsequent days. Only apramycin did not give rise to increasing of ESR. In conclusion the aminoglycosides, especially tobramycin and gentamicin, caused more severe alterations of ESR than the aminocyclitols.

  19. Cryptically patterned moths perceive bark structure when choosing body orientations that match wing color pattern to the bark pattern.

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    Chang-Ku Kang

    Full Text Available Many moths have wing patterns that resemble bark of trees on which they rest. The wing patterns help moths to become camouflaged and to avoid predation because the moths are able to assume specific body orientations that produce a very good match between the pattern on the bark and the pattern on the wings. Furthermore, after landing on a bark moths are able to perceive stimuli that correlate with their crypticity and are able to re-position their bodies to new more cryptic locations and body orientations. However, the proximate mechanisms, i.e. how a moth finds an appropriate resting position and orientation, are poorly studied. Here, we used a geometrid moth Jankowskia fuscaria to examine i whether a choice of resting orientation by moths depends on the properties of natural background, and ii what sensory cues moths use. We studied moths' behavior on natural (a tree log and artificial backgrounds, each of which was designed to mimic one of the hypothetical cues that moths may perceive on a tree trunk (visual pattern, directional furrow structure, and curvature. We found that moths mainly used structural cues from the background when choosing their resting position and orientation. Our findings highlight the possibility that moths use information from one type of sensory modality (structure of furrows is probably detected through tactile channel to achieve crypticity in another sensory modality (visual. This study extends our knowledge of how behavior, sensory systems and morphology of animals interact to produce crypsis.

  20. The complete mitochondrial genome of the cryptic "lineage B" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) in Indo-West Pacific.

    Science.gov (United States)

    Shen, Kang-Ning; Yen, Ta-Chi; Chen, Ching-Hung; Ye, Jeng-Jia; Hsiao, Chung-Der

    2016-05-01

    In this study, the complete mitogenome sequence of the cryptic "lineage B" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) has been sequenced by next-generation sequencing method. The assembled mitogenome consisting of 16,694 bp, includes 13 protein coding genes, 25 transfer RNAs, 2 ribosomal RNAs genes. The overall base composition of "lineage B" S. lessoniana is 36.7% for A, 18.9 % for C, 34.5 % for T and 9.8 % for G and show 90% identities to "lineage C" S. lessoniana. It is also exhibits high T + A content (71.2%), two non-coding regions with TA tandem repeats. The complete mitogenome of the cryptic "lineage B" S. lessoniana provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for big-fin reef squid species complex.

  1. A human PrM antibody that recognizes a novel cryptic epitope on dengue E glycoprotein.

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    Annie Hoi Yi Chan

    Full Text Available Dengue virus (DENV is a major mosquito-borne pathogen infecting up to 100 million people each year; so far no effective treatment or vaccines are available. Recently, highly cross-reactive and infection-enhancing pre-membrane (prM-specific antibodies were found to dominate the anti-DENV immune response in humans, raising concern over vaccine candidates that contain native dengue prM sequences. In this study, we have isolated a broadly cross-reactive prM-specific antibody, D29, during a screen with a non-immunized human Fab-phage library against the four serotypes of DENV. The antibody is capable of restoring the infectivity of virtually non-infectious immature DENV (imDENV in FcγR-bearing K562 cells. Remarkably, D29 also cross-reacted with a cryptic epitope on the envelope (E protein located to the DI/DII junction as evidenced by site-directed mutagenesis. This cryptic epitope, while inaccessible to antibody binding in a native virus particle, may become exposed if E is not properly folded. These findings suggest that generation of anti-prM antibodies that enhance DENV infection may not be completely avoided even with immunization strategies employing E protein alone or subunits of E proteins.

  2. Shoot, shovel and shut up: cryptic poaching slows restoration of a large carnivore in Europe.

    Science.gov (United States)

    Liberg, Olof; Chapron, Guillaume; Wabakken, Petter; Pedersen, Hans Christian; Hobbs, N Thompson; Sand, Håkan

    2012-03-07

    Poaching is a widespread and well-appreciated problem for the conservation of many threatened species. Because poaching is illegal, there is strong incentive for poachers to conceal their activities, and consequently, little data on the effects of poaching on population dynamics are available. Quantifying poaching mortality should be a required knowledge when developing conservation plans for endangered species but is hampered by methodological challenges. We show that rigorous estimates of the effects of poaching relative to other sources of mortality can be obtained with a hierarchical state-space model combined with multiple sources of data. Using the Scandinavian wolf (Canis lupus) population as an illustrative example, we show that poaching accounted for approximately half of total mortality and more than two-thirds of total poaching remained undetected by conventional methods, a source of mortality we term as 'cryptic poaching'. Our simulations suggest that without poaching during the past decade, the population would have been almost four times as large in 2009. Such a severe impact of poaching on population recovery may be widespread among large carnivores. We believe that conservation strategies for large carnivores considering only observed data may not be adequate and should be revised by including and quantifying cryptic poaching.

  3. Virulence and genomic feature of multidrug resistant Campylobacter jejuni isolated from broiler chicken

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    Haihong Hao

    2016-10-01

    Full Text Available The aim of this study was to reveal the molecular mechanism involved in multidrug resistance and virulence of Campylobacter jejuni isolated from broiler chickens. The virulence of six multidrug resistant C. jejuni was determined by in vitro and in vivo methods. The de novo whole genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the multidrug resistance and virulence of a selected isolate (C. jejuni 1655. The comparative genomic analyses revealed a large number of single nucleotide polymorphisms, deletions, rearrangements, and inversions in C. jejuni 1655 compared to reference C. jejuni genomes. The co-emergence of Thr-86-Ile mutation in gyrA gene, A2075G mutation in 23S rRNA gene, tetO, aphA and aadE genes and pTet plasmid in C. jejuni 1655 contributed its multidrug resistance to fluoroquinolones, macrolides, tetracycline and aminoglycosides. The combination of multiple virulence genes may work together to confer the relative higher virulence in C. jejuni 1655. The co-existence of mobile gene elements (e.g. pTet and CRISPR-Cas system in C. jejuni 1655 may play an important role in the gene transfer and immune defense. The present study provides basic information of phenotypic and genomic features of C. jejuni 1655, a strain recently isolated from a chicken displaying multidrug resistance and relatively high level of virulence.

  4. Comparative Genomics of Two ST 195 Carbapenem-Resistant Acinetobacter baumannii with Different Susceptibility to Polymyxin Revealed Underlying Resistance Mechanism

    Science.gov (United States)

    Lean, Soo-Sum; Yeo, Chew Chieng; Suhaili, Zarizal; Thong, Kwai-Lin

    2016-01-01

    Acinetobacter baumannii is a Gram-negative nosocomial pathogen of importance due to its uncanny ability to acquire resistance to most antimicrobials. These include carbapenems, which are the drugs of choice for treating A. baumannii infections, and polymyxins, the drugs of last resort. Whole genome sequencing was performed on two clinical carbapenem-resistant A. baumannii AC29 and AC30 strains which had an indistinguishable ApaI pulsotype but different susceptibilities to polymyxin. Both genomes consisted of an approximately 3.8 Mbp circular chromosome each and several plasmids. AC29 (susceptible to polymyxin) and AC30 (resistant to polymyxin) belonged to the ST195 lineage and are phylogenetically clustered under the International Clone II (IC-II) group. An AbaR4-type resistance island (RI) interrupted the comM gene in the chromosomes of both strains and contained the blaOXA−23 carbapenemase gene and determinants for tetracycline and streptomycin resistance. AC29 harbored another copy of blaOXA−23 in a large (~74 kb) conjugative plasmid, pAC29b, but this gene was absent in a similar plasmid (pAC30c) found in AC30. A 7 kb Tn1548::armA RI which encodes determinants for aminoglycoside and macrolide resistance, is chromosomally-located in AC29 but found in a 16 kb plasmid in AC30, pAC30b. Analysis of known determinants for polymyxin resistance in AC30 showed mutations in the pmrA gene encoding the response regulator of the two-component pmrAB signal transduction system as well as in the lpxD, lpxC, and lpsB genes that encode enzymes involved in the biosynthesis of lipopolysaccharide (LPS). Experimental evidence indicated that impairment of LPS along with overexpression of pmrAB may have contributed to the development of polymyxin resistance in AC30. Cloning of a novel variant of the blaAmpC gene from AC29 and AC30, and its subsequent expression in E. coli also indicated its likely function as an extended-spectrum cephalosporinase. PMID:26779129

  5. Please mind the gap - Visual census and cryptic biodiversity assessment at central Red Sea coral reefs.

    Science.gov (United States)

    Pearman, John K; Anlauf, Holger; Irigoien, Xabier; Carvalho, Susana

    2016-07-01

    Coral reefs harbor the most diverse assemblages in the ocean, however, a large proportion of the diversity is cryptic and, therefore, undetected by standard visual census techniques. Cryptic and exposed communities differ considerably in species composition and ecological function. This study compares three different coral reef assessment protocols: i) visual benthic reef surveys: ii) visual census of Autonomous Reef Monitoring Structures (ARMS) plates; and iii) metabarcoding techniques of the ARMS (including sessile, 106-500 μm and 500-2000 μm size fractions), that target the cryptic and exposed communities of three reefs in the central Red Sea. Visual census showed a dominance of Cnidaria (Anthozoa) and Rhodophyta on the reef substrate, while Porifera, Bryozoa and Rhodophyta were the most abundant groups on the ARMS plates. Metabarcoding, targeting the 18S rRNA gene, significantly increased estimates of the species diversity (p < 0.001); revealing that Annelida were generally the dominant phyla (in terms of reads) of all fractions and reefs. Furthermore, metabarcoding detected microbial eukaryotic groups such as Syndiniophyceae, Mamiellophyceae and Bacillariophyceae as relevant components of the sessile fraction. ANOSIM analysis showed that the three reef sites showed no differences based on the visual census data. Metabarcoding showed a higher sensitivity for identifying differences between reef communities at smaller geographic scales than standard visual census techniques as significant differences in the assemblages were observed amongst the reefs. Comparison of the techniques showed no similar patterns for the visual techniques while the metabarcoding of the ARMS showed similar patterns amongst fractions. Establishing ARMS as a standard tool in reef monitoring will not only advance our understanding of local processes and ecological community response to environmental changes, as different faunal components will provide complementary information but

  6. Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects.

    Science.gov (United States)

    Barbosa, Camilo; Trebosc, Vincent; Kemmer, Christian; Rosenstiel, Philip; Beardmore, Robert; Schulenburg, Hinrich; Jansen, Gunther

    2017-09-01

    When bacteria evolve resistance against a particular antibiotic, they may simultaneously gain increased sensitivity against a second one. Such collateral sensitivity may be exploited to develop novel, sustainable antibiotic treatment strategies aimed at containing the current, dramatic spread of drug resistance. To date, the presence and molecular basis of collateral sensitivity has only been studied in few bacterial species and is unknown for opportunistic human pathogens such as Pseudomonas aeruginosa. In the present study, we assessed patterns of collateral effects by experimentally evolving 160 independent populations of P. aeruginosa to high levels of resistance against eight commonly used antibiotics. The bacteria evolved resistance rapidly and expressed both collateral sensitivity and cross-resistance. The pattern of such collateral effects differed to those previously reported for other bacterial species, suggesting interspecific differences in the underlying evolutionary trade-offs. Intriguingly, we also identified contrasting patterns of collateral sensitivity and cross-resistance among the replicate populations adapted to the same drug. Whole-genome sequencing of 81 independently evolved populations revealed distinct evolutionary paths of resistance to the selective drug, which determined whether bacteria became cross-resistant or collaterally sensitive towards others. Based on genomic and functional genetic analysis, we demonstrate that collateral sensitivity can result from resistance mutations in regulatory genes such as nalC or mexZ, which mediate aminoglycoside sensitivity in β-lactam-adapted populations, or the two-component regulatory system gene pmrB, which enhances penicillin sensitivity in gentamicin-resistant populations. Our findings highlight substantial variation in the evolved collateral effects among replicates, which in turn determine their potential in antibiotic therapy. © The Author 2017. Published by Oxford University Press on

  7. The role of integrative taxonomy in the conservation management of cryptic species: the taxonomic status of endangered earless dragons (Agamidae: Tympanocryptis in the grasslands of Queensland, Australia.

    Directory of Open Access Journals (Sweden)

    Jane Melville

    Full Text Available Molecular phylogenetics is increasingly highlighting the prevalence of cryptic species, where morphologically similar organisms have long independent evolutionary histories. When such cryptic species are known to be declining in numbers and are at risk of extinction due to a range of threatening processes, the disjunction between molecular systematics research and conservation policy becomes a significant problem. We investigate the taxonomic status of Tympanocryptis populations in Queensland, which have previously been assigned to T. tetraporophora, using three species delimitation approaches. The taxonomic uncertainties in this species-group are of particular importance in the Darling Downs Earless Dragon (T. cf. tetraporophora, which is ranked as an endangered 'species' of high priority for conservation by the Queensland Department of Environment and Heritage Protection. We undertook a morphological study, integrated with a comprehensive genetic study and species delimitation analyses, to investigate the species status of populations in the region. Phylogenetic analyses of two gene regions (mtDNA: ND2; nuclear: RAG1 revealed high levels of genetic divergence between populations, indicating isolation over long evolutionary time frames, and strongly supporting two independent evolutionary lineages in southeastern Queensland, from the Darling Downs, and a third in the Gulf Region of northern Queensland. Of the three species delimitation protocols used, we found integrative taxonomy the most applicable to this cryptic species complex. Our study demonstrates the utility of integrative taxonomy as a species delimitation approach in cryptic complexes of species with conservation significance, where limited numbers of specimens are available.

  8. The role of integrative taxonomy in the conservation management of cryptic species: the taxonomic status of endangered earless dragons (Agamidae: Tympanocryptis) in the grasslands of Queensland, Australia.

    Science.gov (United States)

    Melville, Jane; Smith, Katie; Hobson, Rod; Hunjan, Sumitha; Shoo, Luke

    2014-01-01

    Molecular phylogenetics is increasingly highlighting the prevalence of cryptic species, where morphologically similar organisms have long independent evolutionary histories. When such cryptic species are known to be declining in numbers and are at risk of extinction due to a range of threatening processes, the disjunction between molecular systematics research and conservation policy becomes a significant problem. We investigate the taxonomic status of Tympanocryptis populations in Queensland, which have previously been assigned to T. tetraporophora, using three species delimitation approaches. The taxonomic uncertainties in this species-group are of particular importance in the Darling Downs Earless Dragon (T. cf. tetraporophora), which is ranked as an endangered 'species' of high priority for conservation by the Queensland Department of Environment and Heritage Protection. We undertook a morphological study, integrated with a comprehensive genetic study and species delimitation analyses, to investigate the species status of populations in the region. Phylogenetic analyses of two gene regions (mtDNA: ND2; nuclear: RAG1) revealed high levels of genetic divergence between populations, indicating isolation over long evolutionary time frames, and strongly supporting two independent evolutionary lineages in southeastern Queensland, from the Darling Downs, and a third in the Gulf Region of northern Queensland. Of the three species delimitation protocols used, we found integrative taxonomy the most applicable to this cryptic species complex. Our study demonstrates the utility of integrative taxonomy as a species delimitation approach in cryptic complexes of species with conservation significance, where limited numbers of specimens are available.

  9. Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

    Directory of Open Access Journals (Sweden)

    Xiang-hua Hou

    2015-09-01

    Full Text Available Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38 and class II integrons (10/38. All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38, blaTEM (10/38, and blaCTX-M (7/38. The highly conserved blaKPC-2 (37/38 and blaOXA-23(1/38 alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38 and the plasmid-mediated qnrB gene (13/38 were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some

  10. Role of integrons, plasmids and SXT elements in multidrug resistance of Vibrio cholerae and Providencia vermicola obtained from a clinical isolate of diarrhea

    Directory of Open Access Journals (Sweden)

    Neha eRajpara

    2015-02-01

    Full Text Available The isolates of Vibrio cholerae and Providencia vermicola obtained from a diarrhoeal patient were investigated for genetic elements governing their drug resistance phenotypes. Out of fourteen antibiotics tested, V. cholerae Vc IDH02365 isolate showed resistance to nine antibiotics, while P. vermicola Pv NBA2365 was found to be resistant to all the antibiotics except polymyxin B. Though SXT integrase was depicted in both the bacteria, class 1 integron was found to be associated only with Pv NBA2365. Integrons in Pv NBA2365 conferred resistance to β-lactams, aminoglycosides and trimethoprim. Pv NBA2365 carried two transformable plasmids imparting distinct antibiotic resistance traits to their Escherichia coli transformants. In rabbit ileal loop assays, Pv NBA2365 did not show any fluid accumulation in contrast with Vc IDH02365 that showed high fluid accumulation. To the best of our knowledge, this is the first report of a highly drug resistant P.vermicola and additionally co-existence of multidrug resistant V. cholerae and P. vermicola. Both the microbes appeared to possess a wide array of mobile genetic elements for a large spectrum of antimicrobial agents, some of which are being used in the treatment of acute diarrhoea.

  11. Activation of the SOS response increases the frequency of small colony variants

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Paulander, Wilhelm Erik Axel; Ingmer, Hanne

    2015-01-01

    BACKGROUND: In Staphylococcus aureus sub-populations of slow-growing cells forming small colony variants (SCVs) are associated with persistent and recurrent infections that are difficult to eradicate with antibiotic therapies. In SCVs that are resistant towards aminoglycosides, mutations have been...... with different mechanism of action influence the formation of SCVs that are resistant to otherwise lethal concentrations of the aminoglycoside, gentamicin. We found that exposure of S. aureus to fluoroquinolones and mitomycin C increased the frequency of gentamicin resistant SCVs, while other antibiotic classes...... failed to do so. The higher proportion of SCVs in cultures exposed to fluoroquinolones and mitomycin C compared to un-exposed cultures correlate with an increased mutation rate monitored by rifampicin resistance and followed induction of the SOS DNA damage response. CONCLUSION: Our observations suggest...

  12. Characterization of antimicrobial resistance in Salmonella enterica strains isolated from Brazilian poultry production.

    Science.gov (United States)

    Mattiello, Samara P; Drescher, Guilherme; Barth, Valdir C; Ferreira, Carlos A S; Oliveira, Sílvia D

    2015-11-01

    Antimicrobial resistance profiles and presence of resistance determinants and integrons were evaluated in Salmonella enterica strains from Brazilian poultry. The analysis of 203 isolates showed that those from the poultry environment (88 isolates) were significantly more resistant to antimicrobials than isolates from other sources, particularly those isolated from poultry by-product meal (106 isolates). Thirty-seven isolates were resistant to at least three antimicrobial classes. Class 1 integrons were detected in 26 isolates, and the analysis of the variable region between the 5' conserved segment (CS) and 3' CS of each class 1 integron-positive isolate showed that 13 contained a typical 3' CS and 14 contained an atypical 3' CS. One Salmonella Senftenberg isolate harbored two class 1 integrons, showing both typical and atypical 3' CSs. The highest percentage of resistance was found to sulfonamides, and sul genes were detected in the majority of the resistant isolates. Aminoglycoside resistance was detected in 50 isolates, and aadA and aadB were present in 28 and 32 isolates, respectively. In addition, strA and strB were detected in 78.1 and 65.6% isolates resistant to streptomycin, respectively. Twenty-one isolates presented reduced susceptibility to β-lactams and harbored bla(TEM), bla(CMY), and/or bla(CTX-M). Forty isolates showed reduced susceptibility to tetracycline, and most presented tet genes. These results highlight the importance of the environment as a reservoir of resistant Salmonella, which may enable the persistence of resistance determinants in the poultry production chain, contributing, therefore, to the debate regarding the impacts that antimicrobial use in animal production may exert in human health.

  13. Cryptic species of parasitoids attacking the soybean aphid (Hemiptera:Aphididae) in Asia: Binodoxys communis (Gahan) and Binodoxys koreanus (Hymenoptera: Braconidae: Aphidiinae)

    Czech Academy of Sciences Publication Activity Database

    Desneux, N.; Starý, Petr; Delebecque, C. J.; Gariepy, T. D.; Barta, R. J.; Hoelmer, K. A.; Heimpel, G. E.

    2009-01-01

    Roč. 102, č. 6 (2009), s. 925-936 ISSN 0013-8746 Institutional research plan: CEZ:AV0Z50070508 Keywords : cryptic species * Binodoxys communnis * Binodoxys koreanus Subject RIV: EH - Ecology, Behaviour Impact factor: 0.939, year: 2009

  14. Changing prevalence and resistance patterns in children with drug-resistant tuberculosis in Mumbai.

    Science.gov (United States)

    Shah, Ira; Shah, Forum

    2017-05-01

    The prevalence of drug-resistant (DR) tuberculosis (TB) in children is increasing. Although, in India, multi-drug-resistant (MDR) TB rates have been relatively stable, the number of children with pre-extensively drug-resistant and extensively drug-resistant (XDR) TB is increasing. To determine whether the prevalence of DR TB in children in Mumbai is changing and to study the evolving patterns of resistance. A retrospective study was undertaken in 1311 paediatric patients referred between April 2007 and March 2013 to the Paediatric TB clinic at B. J. Wadia Hospital for Children, Mumbai. Children were defined as having DR TB on the basis of drug susceptibility testing (DST) of Mycobacterium tuberculosis grown on culture of body fluids (in the case of extra pulmonary TB) or from gastric lavage/bronchi-alveolar lavage/sputum in patients with pulmonary TB or from DST of the contacts. The prevalence of DR TB was calculated and the type of DR was evaluated yearly and in the pre-2010 and post-2010 eras. The overall prevalence of DR TB was 86 (6.6%) with an increase from 23 (5.6%) patients pre-2010 to 63 (7%) post-2010 (P = 0.40). Nine (10.4%) patients were diagnosed on the basis of contact with a parent with DR TB. Overall fluoroquinolone resistance increased from 9 (39.1%) pre-2010 to 59 (93.7%) post-2010 (P = 0.0001): moxifloxacin resistance increased from 2 (8.7%) to 29 (46%) (P = 0.0018) and ofloxacin resistance increased from 7 (30.4%) to 30 (47.6%) (P = 0.14). Ethionamide resistance also increased from 6 (26.1%) to 31 (49.2%) (P = 0.04), aminoglycoside resistance was one (4.3%) pre-2010 and 12 (19%) post-2010 (P = 0.17) and resistance remained virtually the same for both amikacin [0 pre-2010 and 6 (9.5%) after 2010] and kanamycin [one (4.3%) pre- and 6 (9.5%) post-2010]. Of the first-line drugs, resistance remained the same for isoniazid [23 (100%) to 61 (96.8%)], rifampicin [22 (95.7%) to 51 (80.9%),P = 0.17], pyrazinamide [15 (65.2%) to

  15. The complete mitochondrial genome of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) in Indo-West Pacific.

    Science.gov (United States)

    Hsiao, Chung-Der; Shen, Kang-Ning; Ching, Tzu-Yun; Wang, Ya-Hsien; Ye, Jeng-Jia; Tsai, Shiou-Yi; Wu, Shan-Chun; Chen, Ching-Hung; Wang, Chia-Hui

    2016-07-01

    In this study, the complete mitogenome sequence of the cryptic "lineage A" big-fin reef squid, Sepioteuthis lessoniana (Cephalopoda: Loliginidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consists of 16,605 bp, which includes 13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs genes. The overall base composition of "lineage A" S. lessoniana is 37.5% for A, 17.4% for C, 9.1% for G, and 35.9% for T and shows 87% identities to "lineage C" S. lessoniana. It is also noticed by its high T + A content (73.4%), two non-coding regions with TA tandem repeats. The complete mitogenome of the cryptic "lineage A" S. lessoniana provides essential and important DNA molecular data for further phylogeography and evolutionary analysis for big-fin reef squid species complex.

  16. The complex evolutionary history and phylogeography of Caridina typus (Crustacea: Decapoda): long-distance dispersal and cryptic allopatric species.

    Science.gov (United States)

    Bernardes, Samuel C; Pepato, Almir R; von Rintelen, Thomas; von Rintelen, Kristina; Page, Timothy J; Freitag, Hendrik; de Bruyn, Mark

    2017-08-22

    The evolutionary history of the old, diverse freshwater shrimp genus Caridina is still poorly understood, despite its vast distribution - from Africa to Polynesia. Here, we used nuclear and mitochondrial DNA to infer the phylogeographic and evolutionary history of C. typus, which is one of only four species distributed across the entire range of the genus. Despite this species' potential for high levels of gene flow, questions have been raised regarding its phylogeographic structure and taxonomic status. We identified three distinct lineages that likely diverged in the Miocene. Molecular dating and ancestral range reconstructions are congruent with C. typus' early dispersal to Africa, possibly mediated by the Miocene Indian Ocean Equatorial Jet, followed by back dispersal to Australasia after the Jet's closure. Furthermore, several different species delimitation methods indicate each lineage represents a distinct (cryptic) species, contradicting current morphospecies delimitation of a single C. typus taxon. The evolutionary history of C. typus lineages is complex, in which ancient oceanic current systems and (currently unrecognised) speciation events preceded secondary sympatry of these cryptic species.

  17. Antibiotic resistance marker genes as environmental pollutants in GMO-pristine agricultural soils in Austria.

    Science.gov (United States)

    Woegerbauer, Markus; Zeinzinger, Josef; Gottsberger, Richard Alexander; Pascher, Kathrin; Hufnagl, Peter; Indra, Alexander; Fuchs, Reinhard; Hofrichter, Johannes; Kopacka, Ian; Korschineck, Irina; Schleicher, Corina; Schwarz, Michael; Steinwider, Johann; Springer, Burkhard; Allerberger, Franz; Nielsen, Kaare M; Fuchs, Klemens

    2015-11-01

    Antibiotic resistance genes may be considered as environmental pollutants if anthropogenic emission and manipulations increase their prevalence above usually occurring background levels. The prevalence of aph(3')-IIa/nptII and aph(3')-IIIa/nptIII - frequent marker genes in plant biotechnology conferring resistance to certain aminoglycosides - was determined in Austrian soils from 100 maize and potato fields not yet exposed to but eligible for GMO crop cultivation. Total soil DNA extracts were analysed by nptII/nptIII-specific TaqMan real time PCR. Of all fields 6% were positive for nptII (median: 150 copies/g soil; range: 31-856) and 85% for nptIII (1190 copies/g soil; 13-61600). The copy-number deduced prevalence of nptIII carriers was 14-fold higher compared to nptII. Of the cultivable kanamycin-resistant soil bacteria 1.8% (95% confidence interval: 0-3.3%) were positive for nptIII, none for nptII (0-0.8%). The nptII-load of the studied soils was low rendering nptII a typical candidate as environmental pollutant upon anthropogenic release into these ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. The Endospore-Forming Pathogen Bacillus cereus Exploits a Small Colony Variant-Based Diversification Strategy in Response to Aminoglycoside Exposure.

    Science.gov (United States)

    Frenzel, Elrike; Kranzler, Markus; Stark, Timo D; Hofmann, Thomas; Ehling-Schulz, Monika

    2015-12-08

    Bacillus cereus is among the microorganisms most often isolated from cases of food spoilage and causes gastrointestinal diseases as well as nongastrointestinal infections elicited by the emetic toxin cereulide, enterotoxins, and a panel of tissue-destructive virulence factors. This opportunistic pathogen is increasingly associated with rapidly fatal clinical infections especially linked to neonates and immunocompromised individuals. Fatality results from either the misdiagnosis of B. cereus as a contaminant of the clinical specimen or from failure of antibiotic therapy. Here we report for the first time that exposure to aminoglycoside antibiotics induces a phenotype switching of emetic B. cereus subpopulations to a slow-growing small colony variant (SCV) state. Along with altered antibiotic resistance, SCVs showed distinct phenotypic and metabolic properties, bearing the risk of antibiotic treatment failure and of clinical misdiagnosis by standard identification tests used in routine diagnostic. The SCV subpopulation is characterized by enhanced production of the toxin cereulide, but it does not secrete tissue-destructive and immune system-affecting enzymes such as sphingomyelinase and phospholipase. SCVs showed significantly prolonged persistence and decreased virulence in the Galleria mellonella model for bacterial infections, indicating diversification concerning their ecological lifestyle. Importantly, diversification into coexisting wild-type and SCV subpopulations also emerged during amikacin pressure during in vivo infection experiments. This study shows for the first time that pathogenic spore-forming B. cereus strains are able to switch to a so far unreported slow-growing lifestyle, which differs substantially in terms of developmental, phenotypic, metabolic, and virulence traits from the wild-type populations. This underpins the necessity of molecular-based differential diagnostics and a well-chosen therapeutic treatment strategy in clinical

  19. Hair cell regeneration in the bullfrog vestibular otolith organs following aminoglycoside toxicity

    Science.gov (United States)

    Baird, Richard A.; Torres, M. A.; Schuff, N. R.

    1994-01-01

    Adult bullfrogs were given single intraotic injections of the aminoglycoside antibiotic gentamicin sulfate and sacrificed at postinjection times ranging from 0.5 to 9 days. The saccular and utricular maculae of normal and injected animals were examined in wholemount and cross-section. Intraotic 200 (mu) M gentamicin concentrations resulted in the uniform destruction of the hair bundles and, at later times, the cell bodies of saccular hair cells. In the utriculus, striolar hair cells were selectively damaged while extrastriolar hair cells were relatively unaffected. Regenerating hair cells, identified in sectioned material by their small cell bodies and short, well-formed hair bundles, were seen in the saccular and utricular maculae as early as 24-48 h postinjection. Immature versions of mature hair cell types in both otolith organs were recognized by the presence of absence of a bulbed kinocilia and the relative lengths of their kinocilia and longest sterocilia. Utricular hair cell types with kinocilia longer than their longest stereocilia were observed at earlier times than hair cell types with shorter kinocilia. In the same sacculus, the hair bundles of gentamicin-treated animals, even at 9 days postinjection, were significantly smaller than those of normal animals. The hair bundles of utricular hair cells, on the other hand, reached full maturity within the same time period.

  20. RpoS plays a central role in the SOS induction by sub-lethal aminoglycoside concentrations in Vibrio cholerae.

    Science.gov (United States)

    Baharoglu, Zeynep; Krin, Evelyne; Mazel, Didier

    2013-01-01

    Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC) of aminoglycosides (AGs) induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER) pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC.

  1. Antimicrobial resistance patterns, clinical features, and risk factors for septic shock and death of nosocomial E coli bacteremia in adult patients with hematological disease: A monocenter retrospective study in China.

    Science.gov (United States)

    Ma, Jie; Li, Ning; Liu, Yajie; Wang, Chong; Liu, Xiaoyan; Chen, Shengmei; Xie, Xinsheng; Gan, Silin; Wang, Meng; Cao, Weijie; Wang, Fang; Liu, Yanfan; Wan, Dingming; Sun, Ling; Sun, Hui

    2017-05-01

    aminoglycoside, especially amikacin, will be helpful to increase the antimicrobial coverage against ESBL-EC while combining tigecycline with aminoglycoside should be considered for seriously carbapenem-resistant infectious patients.

  2. Trends in Drug Resistance of Acinetobacter baumannii over a 10-year Period: Nationwide Data from the China Surveillance of Antimicrobial Resistance Program.

    Science.gov (United States)

    Gao, Lei; Lyu, Yuan; Li, Yun

    2017-03-20

    Acinetobacter baumannii has emerged as an important pathogen causing a variety of infections. Using data from the China Surveillance of Antimicrobial Resistance Program conducted biennially, we investigated the secular changes in the resistance of 2917 isolates of A. baumannii from 2004 to 2014 to differ antimicrobial agents. Pathogen samples were collected from 17 to 20 hospitals located in the eastern, central, and western regions of China. Minimum inhibitory concentrations (MICs) were determined by a 2-fold agar dilution method, and antimicrobial susceptibility was established using the 2014 Clinical Laboratory Standards Institute-approved breakpoints. Isolates not susceptible to all the tested aminoglycosides, fluoroquinolones, β-lactams, β-lactam/β-lactam inhibitors and carbapenems were defined as extensively drug resistant. The rates of nonsusceptibility to common antimicrobial agents remained high (>65%) over the years with some fluctuations to certain agents. The prevalence of imipenem-resistant A. baumannii (IRAB) increased from 13.3% in 2004 to 70.5% in 2014 and that of extensively drug-resistant A. baumannii (XDRAB) increased from 11.1% in 2004 to 60.4% in 2014. The activity of tigecycline was stable with MIC90 ≤4 mg/L against A. baumannii from 2009 to 2014. Susceptibility to colistin remained high (97.0%) from 2009 to 2014. The prevalence of XDRAB increased in all the three surveillance regions over the years and was significantly higher in Intensive Care Unit (ICU) wards than non-ICU wards. This longitudinal multicenter surveillance program revealed the nationwide emergence of A. baumannii in China and showed a significant increase in prevalence from 2004 to 2014. High levels of bacterial resistance were detected among samples collected from clinical settings in China, with IRAB and XDRAB being especially prevalent. This study will help to guide empirical therapy and identify at-risk groups requiring more intense interventional infection control

  3. Detection of selected antibiotic resistance genes using multiplex PCR assay in mastitis pathogens in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Vladimir Pyatov

    2017-01-01

    Full Text Available The aim of this research was to develop multiplex polymerase chain reaction assays for the detection of aminoglycoside (strA, strB, sulphonamide (sulI, sulII, tetracycline (tetA, tetB, tetK, tetM, tetO, macrolide and lincosamide (msrA, ermA, ermB, ermC, mefA/E genes of resistance in mastitis pathogens (Escherichia coli, Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae and Streptococcus dysgalactiae. Applying the established assays, we investigated the distribution of antibiotic resistance genes in the above mentioned species isolated from milk samples in the Czech Republic. Each assay consisted of seven pairs of primers. Six of them amplified fragments of antibiotic resistance genes and one pair a fragment of a species specific gene. Polymerase chain reaction conditions were optimized to amplify seven gene fragments simultaneously in one reaction. In total, 249 isolates were used, among which 111 were positive for E. coli, 52 for S. aureus and 86 for Streptococcus spp. The majority (60.2% of bacteria carried at least one antibiotic resistance gene and 44.6% were multidrug-resistant. The designed multiplex polymerase chain reaction assays may be applied as diagnostic method to replace or complement standard techniques of antibiotic susceptibility testing in the mentioned pathogens.

  4. Molecular markers reveal spatially segregated cryptic species in a critically endangered fish, the common skate (Dipturus batis).

    Science.gov (United States)

    Griffiths, Andrew M; Sims, David W; Cotterell, Stephen P; El Nagar, Aliya; Ellis, Jim R; Lynghammar, Arve; McHugh, Matthew; Neat, Francis C; Pade, Nicolas G; Queiroz, Nuno; Serra-Pereira, Bárbara; Rapp, Toby; Wearmouth, Victoria J; Genner, Martin J

    2010-05-22

    Many sharks and skates are particularly vulnerable to overfishing because of their large size, slow growth, late maturity and low fecundity. In Europe dramatic population declines have taken place in common skate (Dipturus batis L.), one of the largest demersal fish in regional shelf seas, leading to extirpations from substantial parts of its former range. Here we report the discovery of cryptic species in common skate collected from the northeast Atlantic continental shelf. Data from nuclear microsatellite markers indicated two clearly distinct clades and phylogenetic analysis of mitochondrial DNA sequences demonstrated monophyly of each one of them. Capture locations showed evidence of strong spatial segregation, with one taxon occurring mainly in waters off the southern British Isles and around Rockall, while the other was restricted to more northerly shelf waters. These apparently cryptic species showed overlapping substrate and depth preferences, but distributional limits were closely related to temperature gradients, potentially indicating thermal limits to their distributions. This discovery of hidden diversity within a large, critically endangered marine vertebrate demonstrates how marine biodiversity can be underestimated, even in such a relatively well-studied and heavily exploited region.

  5. Molecular markers reveal spatially segregated cryptic species in a critically endangered fish, the common skate (Dipturus batis)

    Science.gov (United States)

    Griffiths, Andrew M.; Sims, David W.; Cotterell, Stephen P.; El Nagar, Aliya; Ellis, Jim R.; Lynghammar, Arve; McHugh, Matthew; Neat, Francis C.; Pade, Nicolas G.; Queiroz, Nuno; Serra-Pereira, Bárbara; Rapp, Toby; Wearmouth, Victoria J.; Genner, Martin J.

    2010-01-01

    Many sharks and skates are particularly vulnerable to overfishing because of their large size, slow growth, late maturity and low fecundity. In Europe dramatic population declines have taken place in common skate (Dipturus batis L.), one of the largest demersal fish in regional shelf seas, leading to extirpations from substantial parts of its former range. Here we report the discovery of cryptic species in common skate collected from the northeast Atlantic continental shelf. Data from nuclear microsatellite markers indicated two clearly distinct clades and phylogenetic analysis of mitochondrial DNA sequences demonstrated monophyly of each one of them. Capture locations showed evidence of strong spatial segregation, with one taxon occurring mainly in waters off the southern British Isles and around Rockall, while the other was restricted to more northerly shelf waters. These apparently cryptic species showed overlapping substrate and depth preferences, but distributional limits were closely related to temperature gradients, potentially indicating thermal limits to their distributions. This discovery of hidden diversity within a large, critically endangered marine vertebrate demonstrates how marine biodiversity can be underestimated, even in such a relatively well-studied and heavily exploited region. PMID:20106849

  6. Comparative Genotypes, Staphylococcal Cassette Chromosome mec (SCCmec) Genes and Antimicrobial Resistance amongst Staphylococcus epidermidis and Staphylococcus haemolyticus Isolates from Infections in Humans and Companion Animals.

    Science.gov (United States)

    McManus, Brenda A; Coleman, David C; Deasy, Emily C; Brennan, Gráinne I; O' Connell, Brian; Monecke, Stefan; Ehricht, Ralf; Leggett, Bernadette; Leonard, Nola; Shore, Anna C

    2015-01-01

    This study compares the characteristics of Staphylococcus epidermidis (SE) and Staphylococcus haemolyticus (SH) isolates from epidemiologically unrelated infections in humans (Hu) (28 SE-Hu; 8 SH-Hu) and companion animals (CpA) (12 SE-CpA; 13 SH-CpA). All isolates underwent antimicrobial susceptibility testing, multilocus sequence typing and DNA microarray profiling to detect antimicrobial resistance and SCCmec-associated genes. All methicillin-resistant (MR) isolates (33/40 SE, 20/21 SH) underwent dru and mecA allele typing. Isolates were predominantly assigned to sequence types (STs) within a single clonal complex (CC2, SE, 84.8%; CC1, SH, 95.2%). SCCmec IV predominated among MRSE with ST2-MRSE-IVc common to both Hu (40.9%) and CpA (54.5%). Identical mecA alleles and nontypeable dru types (dts) were identified in one ST2-MRSE-IVc Hu and CpA isolate, however, all mecA alleles and 2/4 dts detected among 18 ST2-MRSE-IVc isolates were closely related, sharing >96.5% DNA sequence homology. Although only one ST-SCCmec type combination (ST1 with a non-typeable [NT] SCCmec NT9 [class C mec and ccrB4]) was common to four MRSH-Hu and one MRSH-CpA, all MRSH isolates were closely related based on similar STs, SCCmec genes (V/VT or components thereof), mecA alleles and dts. Overall, 39.6% of MR isolates harbored NT SCCmec elements, and ACME was more common amongst MRSE and CpA isolates. Multidrug resistance (MDR) was detected among 96.7% of isolates but they differed in the prevalence of specific macrolide, aminoglycoside and trimethoprim resistance genes amongst SE and SH isolates. Ciprofloxacin, rifampicin, chloramphenicol [fexA, cat-pC221], tetracycline [tet(K)], aminoglycosides [aadD, aphA3] and fusidic acid [fusB] resistance was significantly more common amongst CpA isolates. SE and SH isolates causing infections in Hu and CpA hosts belong predominantly to STs within a single lineage, harboring similar but variable SCCmec genes, mecA alleles and dts. Host and

  7. Comparative Genotypes, Staphylococcal Cassette Chromosome mec (SCCmec Genes and Antimicrobial Resistance amongst Staphylococcus epidermidis and Staphylococcus haemolyticus Isolates from Infections in Humans and Companion Animals.

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    Brenda A McManus

    Full Text Available This study compares the characteristics of Staphylococcus epidermidis (SE and Staphylococcus haemolyticus (SH isolates from epidemiologically unrelated infections in humans (Hu (28 SE-Hu; 8 SH-Hu and companion animals (CpA (12 SE-CpA; 13 SH-CpA. All isolates underwent antimicrobial susceptibility testing, multilocus sequence typing and DNA microarray profiling to detect antimicrobial resistance and SCCmec-associated genes. All methicillin-resistant (MR isolates (33/40 SE, 20/21 SH underwent dru and mecA allele typing. Isolates were predominantly assigned to sequence types (STs within a single clonal complex (CC2, SE, 84.8%; CC1, SH, 95.2%. SCCmec IV predominated among MRSE with ST2-MRSE-IVc common to both Hu (40.9% and CpA (54.5%. Identical mecA alleles and nontypeable dru types (dts were identified in one ST2-MRSE-IVc Hu and CpA isolate, however, all mecA alleles and 2/4 dts detected among 18 ST2-MRSE-IVc isolates were closely related, sharing >96.5% DNA sequence homology. Although only one ST-SCCmec type combination (ST1 with a non-typeable [NT] SCCmec NT9 [class C mec and ccrB4] was common to four MRSH-Hu and one MRSH-CpA, all MRSH isolates were closely related based on similar STs, SCCmec genes (V/VT or components thereof, mecA alleles and dts. Overall, 39.6% of MR isolates harbored NT SCCmec elements, and ACME was more common amongst MRSE and CpA isolates. Multidrug resistance (MDR was detected among 96.7% of isolates but they differed in the prevalence of specific macrolide, aminoglycoside and trimethoprim resistance genes amongst SE and SH isolates. Ciprofloxacin, rifampicin, chloramphenicol [fexA, cat-pC221], tetracycline [tet(K], aminoglycosides [aadD, aphA3] and fusidic acid [fusB] resistance was significantly more common amongst CpA isolates. SE and SH isolates causing infections in Hu and CpA hosts belong predominantly to STs within a single lineage, harboring similar but variable SCCmec genes, mecA alleles and dts. Host and

  8. A Cryptic Sulfur Cycle in Oxygen-Minimum-Zone Waters off the Chilean Coast

    Science.gov (United States)

    Canfield, Don E.; Stewart, Frank J.; Thamdrup, Bo; De Brabandere, Loreto; Dalsgaard, Tage; Delong, Edward F.; Revsbech, Niels Peter; Ulloa, Osvaldo

    2010-12-01

    Nitrogen cycling is normally thought to dominate the biogeochemistry and microbial ecology of oxygen-minimum zones in marine environments. Through a combination of molecular techniques and process rate measurements, we showed that both sulfate reduction and sulfide oxidation contribute to energy flux and elemental cycling in oxygen-free waters off the coast of northern Chile. These processes may have been overlooked because in nature, the sulfide produced by sulfate reduction immediately oxidizes back to sulfate. This cryptic sulfur cycle is linked to anammox and other nitrogen cycling processes, suggesting that it may influence biogeochemical cycling in the global ocean.

  9. Small mammals as indicators of cryptic plant species diversity in the central Chilean plant endemicity hotspot

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    Meredith Root-Bernstein

    2014-12-01

    Full Text Available Indicator species could help to compensate for a shortfall of knowledge about the diversity and distributions of undersampled and cryptic species. This paper provides background knowledge about the ecological interactions that affect and are affected by herbaceous diversity in central Chile, as part of the indicator species selection process. We focus on the ecosystem engineering role of small mammals, primarily the degu Octodon degus. We also consider the interacting effects of shrubs, trees, avian activity, livestock, slope, and soil quality on herbaceous communities in central Chile. We sampled herbaceous diversity on a private landholding characterized by a mosaic of savanna, grassland and matorral, across a range of degu disturbance intensities. We find that the strongest factors affecting endemic herbaceous diversity are density of degu runways, shrub cover and avian activity. Our results show that the degu, a charismatic and easily identifiable and countable species, could be used as an indicator species to aid potential conservation actions such as private protected area uptake. We map areas in central Chile where degus may indicate endemic plant diversity. This area is larger than expected, and suggests that significant areas of endemic plant communities may still exist, and should be identified and protected. Keywords: Cryptic species, Diversity, Endemic, Indicator species, Octodon degus, Plant

  10. Cross-shelf investigation of coral reef cryptic benthic organisms reveals diversity patterns of the hidden majority

    KAUST Repository

    Pearman, John K.

    2018-05-18

    Coral reefs harbor diverse assemblages of organisms yet the majority of this diversity is hidden within the three dimensional structure of the reef and neglected using standard visual surveys. This study uses Autonomous Reef Monitoring Structures (ARMS) and amplicon sequencing methodologies, targeting mitochondrial cytochrome oxidase I and 18S rRNA genes, to investigate changes in the cryptic reef biodiversity. ARMS, deployed at 11 sites across a near- to off-shore gradient in the Red Sea were dominated by Porifera (sessile fraction), Arthropoda and Annelida (mobile fractions). The two primer sets detected different taxa lists, but patterns in community composition and structure were similar. While the microhabitat of the ARMS deployment affected the community structure, a clear cross-shelf gradient was observed for all fractions investigated. The partitioning of beta-diversity revealed that replacement (i.e. the substitution of species) made the highest contribution with richness playing a smaller role. Hence, different reef habitats across the shelf are relevant to regional diversity, as they harbor different communities, a result with clear implications for the design of Marine Protected Areas. ARMS can be vital tools to assess biodiversity patterns in the generally neglected but species-rich cryptic benthos, providing invaluable information for the management and conservation of hard-bottomed habitats over local and global scales.

  11. PCR Screening of Antibiotic Resistance Genes in Faecal Samples from Australian and Chinese Children.

    Science.gov (United States)

    Ravensdale, Joshua T; Xian, Darren Ten Wei; Wei, Chooi Ming; Lv, Quanjun; Wen, Xiajian; Guo, Jing; Coorey, Ranil; LeSouëf, Peter; Lu, Fengmin; Zhang, Brad; Dykes, Gary A

    2018-03-31

    Recent public awareness campaigns on the risk of antibiotic resistance in pathogenic microbes has placed pressure on governments to enforce stricter antimicrobial stewardship policies on the hospital and agricultural industry. This study aimed to screen faecal samples from Australian and Chinese children for the presence of antibiotic resistance genes to identify demographics at risk of carriage of these genes and examine antimicrobial stewardship policies from the two countries which may influence carriage. Faecal samples from 46 Australian and 53 Chinese children were screened for the presence of six clinically relevant antibiotic resistance genes using PCR. Clinical and demographic data was also collected from each patient. Over 90% of faecal samples from Chinese children tested positive for β-lactam, macrolide, tetracycline, and aminoglycoside resistance genes, which was substantially higher than Australian samples. Besides country of origin, no clear trend could be seen to predict carriage of resistance genes. The exception to this was Chinese born children who immigrated to Australia having higher rates of carriage for bla TEM and tetM genes than children born and still living in Australia. These data indicated that Chinese children were more likely to carry certain antibiotic resistance genes than Australian children. The Chinese government has recently implemented strict policies to control the overuse of antibiotics in hospitals. However, many of these policies do not extend to the agricultural industry which could explain the differences seen in this study. Copyright © 2018. Published by Elsevier Ltd.

  12. Please mind the gap – Visual census and cryptic biodiversity assessment at central Red Sea coral reefs

    KAUST Repository

    Pearman, John K.

    2016-04-26

    Coral reefs harbor the most diverse assemblages in the ocean, however, a large proportion of the diversity is cryptic and, therefore, undetected by standard visual census techniques. Cryptic and exposed communities differ considerably in species composition and ecological function. This study compares three different coral reef assessment protocols: i) visual benthic reef surveys: ii) visual census of Autonomous Reef Monitoring Structures (ARMS) plates; and iii) metabarcoding techniques of the ARMS (including sessile, 106–500 μm and 500–2000 μm size fractions), that target the cryptic and exposed communities of three reefs in the central Red Sea. Visual census showed a dominance of Cnidaria (Anthozoa) and Rhodophyta on the reef substrate, while Porifera, Bryozoa and Rhodophyta were the most abundant groups on the ARMS plates. Metabarcoding, targeting the 18S rRNA gene, significantly increased estimates of the species diversity (p < 0.001); revealing that Annelida were generally the dominant phyla (in terms of reads) of all fractions and reefs. Furthermore, metabarcoding detected microbial eukaryotic groups such as Syndiniophyceae, Mamiellophyceae and Bacillariophyceae as relevant components of the sessile fraction. ANOSIM analysis showed that the three reef sites showed no differences based on the visual census data. Metabarcoding showed a higher sensitivity for identifying differences between reef communities at smaller geographic scales than standard visual census techniques as significant differences in the assemblages were observed amongst the reefs. Comparison of the techniques showed no similar patterns for the visual techniques while the metabarcoding of the ARMS showed similar patterns amongst fractions. Establishing ARMS as a standard tool in reef monitoring will not only advance our understanding of local processes and ecological community response to environmental changes, as different faunal components will provide complementary information but

  13. Please mind the gap – Visual census and cryptic biodiversity assessment at central Red Sea coral reefs

    KAUST Repository

    Pearman, John K.; Anlauf, Holger; Irigoien, Xabier; Carvalho, Susana

    2016-01-01

    Coral reefs harbor the most diverse assemblages in the ocean, however, a large proportion of the diversity is cryptic and, therefore, undetected by standard visual census techniques. Cryptic and exposed communities differ considerably in species composition and ecological function. This study compares three different coral reef assessment protocols: i) visual benthic reef surveys: ii) visual census of Autonomous Reef Monitoring Structures (ARMS) plates; and iii) metabarcoding techniques of the ARMS (including sessile, 106–500 μm and 500–2000 μm size fractions), that target the cryptic and exposed communities of three reefs in the central Red Sea. Visual census showed a dominance of Cnidaria (Anthozoa) and Rhodophyta on the reef substrate, while Porifera, Bryozoa and Rhodophyta were the most abundant groups on the ARMS plates. Metabarcoding, targeting the 18S rRNA gene, significantly increased estimates of the species diversity (p < 0.001); revealing that Annelida were generally the dominant phyla (in terms of reads) of all fractions and reefs. Furthermore, metabarcoding detected microbial eukaryotic groups such as Syndiniophyceae, Mamiellophyceae and Bacillariophyceae as relevant components of the sessile fraction. ANOSIM analysis showed that the three reef sites showed no differences based on the visual census data. Metabarcoding showed a higher sensitivity for identifying differences between reef communities at smaller geographic scales than standard visual census techniques as significant differences in the assemblages were observed amongst the reefs. Comparison of the techniques showed no similar patterns for the visual techniques while the metabarcoding of the ARMS showed similar patterns amongst fractions. Establishing ARMS as a standard tool in reef monitoring will not only advance our understanding of local processes and ecological community response to environmental changes, as different faunal components will provide complementary information but

  14. Nuclear modifier MTO2 modulates the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae.

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    Xiangyu He

    Full Text Available The phenotypic manifestations of mitochondrial DNA (mtDNA mutations are modulated by mitochondrial DNA haplotypes, nuclear modifier genes and environmental factors. The yeast mitochondrial 15S rRNA C1477G (P(R or P(R 454 mutation corresponds to the human 12S rRNA C1494T and A1555G mutations, which are well known as primary factors for aminoglycoside-induced nonsyndromic deafness. Here we report that the deletion of the nuclear modifier gene MTO2 suppressed the aminoglycoside-sensitivity of mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae. First, the strain with a single mtDNA C1477G mutation exhibited hypersensitivity to neomycin. Functional assays indicated that the steady-state transcription level of mitochondrial DNA, the mitochondrial respiratory rate, and the membrane potential decreased significantly after neomycin treatment. The impaired mitochondria could not produce sufficient energy to maintain cell viability. Second, when the mto2 null and the mitochondrial C1477G mutations co-existed (mto2(P(R, the oxygen consumption rate in the double mutant decreased markedly compared to that of the control strains (MTO2(P(S, mto2(P(S and MTO2(P(R. The expression levels of the key glycolytic genes HXK2, PFK1 and PYK1 in the mto2(P(R strain were stimulated by neomycin and up-regulated by 89%, 112% and 55%, respectively. The enhanced glycolysis compensated for the respiratory energy deficits, and could be inhibited by the glycolytic enzyme inhibitor. Our findings in yeast will provide a new insight into the pathogenesis of human deafness.

  15. The impact of nosocomially-acquired resistant Pseudomonas aeruginosa infection in a burn unit.

    Science.gov (United States)

    Armour, Alexis D; Shankowsky, Heather A; Swanson, Todd; Lee, Jonathan; Tredget, Edward E

    2007-07-01

    Nosocomially-acquired Pseudomonas aeruginosa remains a serious cause of infection and septic mortality in burn patients. This study was conducted to quantify the impact of nosocomially-transmitted resistant P. aeruginosa in a burn population. Using a TRACS burn database, 48 patients with P. aeruginosa resistant to gentamicin were identified (Pseudomonas group). Thirty-nine were case-matched to controls without resistant P. aeruginosa cultures (control group) for age, total body surface area, admission year, and presence of inhalation injury. Mortality and various morbidity endpoints were examined, as well as antibiotic costs. There was a significantly higher mortality rate in the Pseudomonas group (33% vs. 8%, p products used (packed cells 51.1 +/- 8.0 vs. 21.1 +/- 3.4, p < 0.01; platelets 11.9 +/- 3.0 vs. 1.4 +/- 0.7, p < 0.01) were all significantly higher in the Pseudomonas group. Cost of antibiotics was also significantly higher ($2,658.52 +/- $647.93 vs. $829.22 +/- $152.82, p < 0.01). Nosocomial colonization or infection, or both, of burn patients with aminoglycoside-resistant P. aeruginosa is associated with significantly higher morbidity, mortality, and cost of care. Increased resource consumption did not prevent significantly higher mortality rates when compared with that of control patients. Thus, prevention, identification, and eradication of nosocomial Pseudomonas contamination are critical for cost-effective, successful burn care.

  16. Plasmid-mediated quinolone resistance; interactions between human, animal and environmental ecologies

    Directory of Open Access Journals (Sweden)

    Laurent ePOIREL

    2012-02-01

    Full Text Available Resistance to quinolones and fluoroquinolones is being increasingly reported among human but also veterinary isolates during the last two to three decades, very likely as a consequence of the large clinical usage of those antibiotics. Even if the principle mechanisms of resistance to quinolones are chromosome-encoded, due to modifications of molecular targets (DNA gyrase and topoisomerase IV, decreased outer-membrane permeability (porin defect and overexpression of naturally-occurring efflux, the emergence of plasmid-mediated quinolone resistance (PMQR has been reported since 1998. Although these PMQR determinants confer low-level resistance to quinolones and/or fluoroquinolones, they are a favorable background for selection of additional chromosome-encoded quinolone resistance mechanisms. Different transferable mechanisms have been identified, corresponding to the production of Qnr proteins, of the aminoglycoside acetyltransferase AAC(6’-Ib-cr, or of the QepA-type or OqxAB-type efflux pumps. Qnr proteins protect target enzymes (DNA gyrase and type IV topoisomerase from quinolone inhibition (mostly nalidixic acid. The AAC(6’-Ib-cr determinant acetylates several fluoroquinolones, such as norfloxacin and ciprofloxacin. Finally, the QepA and OqxAB efflux pumps extrude fluoroquinolones from the bacterial cell. A series of studies have identified the environment to be a reservoir of PMQR genes, with farm animals and aquatic habitats being significantly involved. In addition, the origin of the qnr genes has been identified, corresponding to the waterborne species Shewanella sp. Altogether, the recent observations suggest that the aquatic environment might constitute the original source of PMQR genes, that would secondly spread among animal or human isolates.

  17. Contamination delays the release of Laricobius osakensis for biological control of hemlock woolly adelgid: cryptic diversity in Japanese Laricobius spp

    Science.gov (United States)

    Melissa J. Fischer; Nathan P. Havill; Carrie S. Jubb; Sean W. Prosser; Brent D. Opell; Scott M. Salom; Loke T. Kok

    2014-01-01

    Laricobius osakensis (Coleoptera: Derodontidae) was imported from Japan to the United States in 2006 for study in quarantine facilities as a potential biological control of Hemlock Woolly Adelgid. Laricobius osakensis was released from quarantine in 2010, but it was soon discovered that the colony also contained a cryptic species...

  18. Prevalence and antibiotic resistance of 15 minor staphylococcal species colonizing orthopedic implants.

    Science.gov (United States)

    Arciola, C R; Campoccia, D; An, Y H; Baldassarri, L; Pirini, V; Donati, M E; Pegreffi, F; Montanaro, L

    2006-04-01

    Several species belonging to Staphylococcus genus (non Sau/ non Sep species) exhibit increasing abilities as opportunistic pathogens in colonisation of periprosthesis tissues. Here we report on antibiotic resistance of 193 strains, belonging to non Sau/ non Sep species, consecutively collected from orthopedic implant infections in a period of about 40 months. The 193 strains (representing 17% of all staphylococci isolated) were analysed for their antibiotic resistance to 16 different drugs. Five species turned out more prevalent, ranging from 1 to 5%: S. hominis (4.2%), S. haemolyticus (3.7%), S. capitis (2.7%), S. warneri (2.6%), and S. cohnii (1.6%). Among these, the prevalence of antibiotic resistance to penicillins was similar, ranging from 51% to 66%. Conversely, significant differences were observed for all the remaining antibiotics. For S. haemolyticus the resistances to oxacillin and imipenem, the four aminoglycosides and erythromycin were at least twice that of the other three species which were compared. S. warneri was on the contrary the species with the lowest occurrence of resistant strains. Ten species appeared only rarely at the infection sites: S. lugdunensis, S. caprae, S. equorum, S. intermedius, S. xylosus, S. simulans, S. saprophyticus, S. pasteuri, S. sciuri, and S. schleiferi. The behaviours of these species, often resistant to penicillins, were individually analysed. Differences in both the frequencies and the panels of antibiotic resistances observed among the non Sau/ non Sep species: i) suggest that horizontal spreading of resistance factors, if acting, was not sufficient per se to level their bio-diversities; ii) highlight and confirm the worrisome appearance within the Staphylococcus genus of emerging "new pathogens", not homogeneous for their virulence and antibiotic resistance prevalence, which deserve to be recognised and treated individually.

  19. Diagnosis of Familial Wolf-Hirschhorn Syndrome due to a Paternal Cryptic Chromosomal Rearrangement by Conventional and Molecular Cytogenetic Techniques

    Science.gov (United States)

    Venegas-Vega, Carlos A.; Zepeda, Luis M.; Garduño-Zarazúa, Luz M.; Berumen, Jaime; Kofman, Susana; Cervantes, Alicia

    2013-01-01

    The use of conventional cytogenetic techniques in combination with fluorescent in situ hybridization (FISH) and single-nucleotide polymorphism (SNP) microarrays is necessary for the identification of cryptic rearrangements in the diagnosis of chromosomal syndromes. We report two siblings, a boy of 9 years and 9 months of age and his 7-years- and 5-month-old sister, with the classic Wolf-Hirschhorn syndrome (WHS) phenotype. Using high-resolution GTG- and NOR-banding karyotypes, as well as FISH analysis, we characterized a pure 4p deletion in both sibs and a balanced rearrangement in their father, consisting in an insertion of 4p material within a nucleolar organizing region of chromosome 15. Copy number variant (CNV) analysis using SNP arrays showed that both siblings have a similar size of 4p deletion (~6.5 Mb). Our results strongly support the need for conventional cytogenetic and FISH analysis, as well as high-density microarray mapping for the optimal characterization of the genetic imbalance in patients with WHS; parents must always be studied for recognizing cryptic balanced chromosomal rearrangements for an adequate genetic counseling. PMID:23484094

  20. Cryptic cuckoo eggs hide from competing cuckoos

    Science.gov (United States)

    Gloag, Ros; Keller, Laurie-Anne; Langmore, Naomi E.

    2014-01-01

    Interspecific arms races between cuckoos and their hosts have produced remarkable examples of mimicry, with parasite eggs evolving to match host egg appearance and so evade removal by hosts. Certain bronze-cuckoo species, however, lay eggs that are cryptic rather than mimetic. These eggs are coated in a low luminance pigment that camouflages them within the dark interiors of hosts' nests. We investigated whether cuckoo egg crypsis is likely to have arisen from the same coevolutionary processes known to favour egg mimicry. We added high and low luminance-painted eggs to the nests of large-billed gerygones (Gerygone magnirostris), a host of the little bronze-cuckoo (Chalcites minutillus). Gerygones rarely rejected either egg type, and did not reject natural cuckoo eggs. Cuckoos, by contrast, regularly removed an egg from clutches before laying their own and were five times more likely to remove a high luminance model than its low luminance counterpart. Given that we found one-third of all parasitized nests were exploited by multiple cuckoos, our results suggest that competition between cuckoos has been the key selective agent for egg crypsis. In such intraspecific arms races, crypsis may be favoured over mimicry because it can reduce the risk of egg removal to levels below chance. PMID:25122227

  1. Genetic relatedness and molecular characterization of multidrug resistant Acinetobacter baumannii isolated in central Ohio, USA

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    Tadesse Daniel

    2009-06-01

    Full Text Available Abstract Background Over the last decade, nosocomial infections due to Acinetobacter baumannii have been described with an increasing trend towards multidrug resistance, mostly in intensive care units. The aim of the present study was to determine the clonal relatedness of clinical isolates and to elucidate the genetic basis of imipenem resistance. Methods A. baumannii isolates (n = 83 originated from two hospital settings in central Ohio were used in this study. Pulsed-field gel electrophoresis genotyping and antimicrobial susceptibility testing for clinically relevant antimicrobials were performed. Resistance determinants were characterized by using different phenotypic (accumulation assay for efflux and genotypic (PCR, DNA sequencing, plasmid analysis and electroporation approaches. Results The isolates were predominantly multidrug resistant (>79.5% and comprised of thirteen unique pulsotypes, with genotype VII circulating in both hospitals. The presence of blaOXA-23 in 13% (11/83 and ISAba1 linked blaOXA-66 in 79.5% (66/83 of clinical isolates was associated with high level imipenem resistance. In this set of OXA producing isolates, multidrug resistance was bestowed by blaADC-25, class 1 integron-borne aminoglycoside modifying enzymes, presence of sense mutations in gyrA/parC and involvement of active efflux (with evidence for the presence of adeB efflux gene. Conclusion This study underscores the major role of carbapenem-hydrolyzing class D β-lactamases, and in particular the acquired OXA-23, in the dissemination of imipenem-resistant A. baumannii. The co-occurrence of additional resistance determinant could also be a significant threat.

  2. Characterization of Multidrug Resistant E. faecalis Strains from Pigs of Local Origin by ADSRRS-Fingerprinting and MALDI -TOF MS; Evaluation of the Compatibility of Methods Employed for Multidrug Resistance Analysis.

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    Aneta Nowakiewicz

    Full Text Available The aim of this study was to characterize multidrug resistant E. faecalis strains from pigs of local origin and to analyse the relationship between resistance and genotypic and proteomic profiles by amplification of DNA fragments surrounding rare restriction sites (ADSRRS-fingerprinting and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI -TOF MS. From the total pool of Enterococcus spp. isolated from 90 pigs, we selected 36 multidrug resistant E. faecalis strains, which represented three different phenotypic resistance profiles. Phenotypic resistance to tetracycline, macrolides, phenicols, and lincomycin and high-level resistance to aminoglycosides were confirmed by the occurrence of at least one corresponding resistance gene in each strain. Based on the analysis of the genotypic and phenotypic resistance of the strains tested, five distinct resistance profiles were generated. As a complement of this analysis, profiles of virulence genes were determined and these profiles corresponded to the phenotypic resistance profiles. The demonstration of resistance to a wide panel of antimicrobials by the strains tested in this study indicates the need of typing to determine the spread of resistance also at the local level. It seems that in the case of E. faecalis, type and scope of resistance strongly determines the genotypic pattern obtained with the ADSRRS-fingerprinting method. The ADSRRS-fingerprinting analysis showed consistency of the genetic profiles with the resistance profiles, while analysis of data with the use of the MALDI- TOF MS method did not demonstrate direct reproduction of the clustering pattern obtained with this method. Our observations were confirmed by statistical analysis (Simpson's index of diversity, Rand and Wallace coefficients. Even though the MALDI -TOF MS method showed slightly higher discrimination power than ADSRRS-fingerprinting, only the latter method allowed reproduction of the

  3. The Genomic Basis of Intrinsic and Acquired Antibiotic Resistance in the Genus Serratia

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    Luisa Sandner-Miranda

    2018-05-01

    Full Text Available Serratia marcescens, a member of the Enterobacteriaceae family, was long thought to be a non-pathogenic bacterium prevalent in environmental habitats. Together with other members of this genus, it has emerged in recent years as an opportunistic nosocomial pathogen causing various types of infections. One important feature of pathogens belonging to this genus is their intrinsic and acquired resistance to a variety of antibiotic families, including β-lactam, aminoglycosides, quinolones and polypeptide antibiotics. The aim of this study was to elucidate which genes participate in the intrinsic and acquired antibiotic resistance of this genus in order to determine the Serratia genus resistome. We performed phylogenomic and comparative genomic analyses using 32 Serratia spp. genomes deposited in the NCBI GenBank from strains isolated from different ecological niches and different lifestyles. S. marcescens strain SmUNAM836, which was previously isolated from a Mexican adult with obstructive pulmonary disease, was included in this study. The results show that most of the antibiotic resistance genes (ARGs were found on the chromosome, and to a lesser degree, on plasmids and transposons acquired through horizontal gene transfer. Four strains contained the gyrA point mutation in codon Ser83 that confers quinolone resistance. Pathogenic and environmental isolates presented a high number of ARGs, especially genes associated with efflux systems. Pathogenic strains, specifically nosocomial strains, presented more acquired resistance genes than environmental isolates. We may conclude that the environment provides a natural reservoir for antibiotic resistance, which has been underestimated in the medical field.

  4. The Genomic Basis of Intrinsic and Acquired Antibiotic Resistance in the Genus Serratia

    Science.gov (United States)

    Sandner-Miranda, Luisa; Vinuesa, Pablo; Cravioto, Alejandro; Morales-Espinosa, Rosario

    2018-01-01

    Serratia marcescens, a member of the Enterobacteriaceae family, was long thought to be a non-pathogenic bacterium prevalent in environmental habitats. Together with other members of this genus, it has emerged in recent years as an opportunistic nosocomial pathogen causing various types of infections. One important feature of pathogens belonging to this genus is their intrinsic and acquired resistance to a variety of antibiotic families, including β-lactam, aminoglycosides, quinolones and polypeptide antibiotics. The aim of this study was to elucidate which genes participate in the intrinsic and acquired antibiotic resistance of this genus in order to determine the Serratia genus resistome. We performed phylogenomic and comparative genomic analyses using 32 Serratia spp. genomes deposited in the NCBI GenBank from strains isolated from different ecological niches and different lifestyles. S. marcescens strain SmUNAM836, which was previously isolated from a Mexican adult with obstructive pulmonary disease, was included in this study. The results show that most of the antibiotic resistance genes (ARGs) were found on the chromosome, and to a lesser degree, on plasmids and transposons acquired through horizontal gene transfer. Four strains contained the gyrA point mutation in codon Ser83 that confers quinolone resistance. Pathogenic and environmental isolates presented a high number of ARGs, especially genes associated with efflux systems. Pathogenic strains, specifically nosocomial strains, presented more acquired resistance genes than environmental isolates. We may conclude that the environment provides a natural reservoir for antibiotic resistance, which has been underestimated in the medical field.

  5. High diversity of genes and plasmids encoding resistance to third-generation cephalosporins and quinolones in clinical Escherichia coli from commercial poultry flocks in Italy

    DEFF Research Database (Denmark)

    Niero, Giulia; Bortolaia, Valeria; Vanni, Michele

    2018-01-01

    = 98) and layers (n = 22) between 2008 and 2012. 3GC-resistant isolates were screened for extended-spectrum and AmpC β-lactamase (ESBL/AmpC), while all isolates were tested for plasmid-mediated quinolone resistance (PMQR) genes. ESBL/AmpC- and PMQR-positive isolates were typed by pulsed-field gel......% of isolates from turkeys, broilers and layers, respectively. We identified seven ESBL/AmpC-encoding plasmid types, usually conjugative (78%), with a marked prevalence of IncI1/pST3 plasmids carrying blaCTX-M-1. PMQR occurred less frequently among isolates from turkeys (0.9%) compared to those from broilers (5......%) and layers (4%). The PMQR genes qnrS, qnrB19 and oqxA/B were located on three plasmid types and two non-typeable plasmids, mostly (85%) conjugative. ESBL/AmpC- and PMQR-positive isolates were genetically unrelated and 64% of them were additionally resistant to aminoglycosides, sulfonamides and tetracyclines...

  6. Hearing loss in children treated for multidrug-resistant tuberculosis.

    Science.gov (United States)

    Seddon, James A; Thee, Stephanie; Jacobs, Kayleen; Ebrahim, Adam; Hesseling, Anneke C; Schaaf, H Simon

    2013-04-01

    The aminoglycosides and polypeptides are vital drugs for the management of multidrug-resistant (MDR) tuberculosis (TB). Both classes of drug cause hearing loss. We aimed to determine the extent of hearing loss in children treated for MDR-TB. In this retrospective study, children (Hearing was assessed and classified using audiometry and otoacoustic emissions. Ninety-four children were included (median age: 43 months). Of 93 tested, 28 (30%) were HIV-infected. Twenty-three (24%) children had hearing loss. Culture-confirmed, as opposed to presumed, diagnosis of TB was a risk factor for hearing loss (OR: 4.12; 95% CI: 1.13-15.0; p = 0.02). Seven of 11 (64%) children classified as having hearing loss using audiometry had progression of hearing loss after finishing the injectable drug. Hearing loss is common in children treated for MDR-TB. Alternative drugs are required for the treatment of paediatric MDR-TB. Copyright © 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

  7. Isolation and identification of antibiotic resistance genes in Staphylococcus aureus isolates from respiratory system infections in shahrekord, Iran

    Directory of Open Access Journals (Sweden)

    Maryam Reisi

    2014-07-01

    Full Text Available   Introduction : Staphylococcus aureus is considered as one of pathogenic agents in humans, that engages different body parts including respiratory system and causes to spend lots of costs and extending patient’s treatment period. This study which is performed to separate and investigate the pattern of antibiotic resistance in Staphylococcus aureus isolates from upper respiratory system infections in Shahrekord.   Materials and methods: This study was done by sectional-descriptive method On 200 suspicious persons to the upper respiratory system infections who were referred to the Imam Ali clinic in Shahrekord in 2012. After isolation of Staphylococcus aureus from cultured nose discharges, antibiotic resistance genes were identified by polymerase chain reaction (PCR by using defined primer pairs .   Results : Among 200 investigated samples in 60 cases (30% Staphylococcus aureus infection (by culturing and PCR method was determined. Isolates showed the lowest amount of antibiotic resistance to vancomycin (0.5% and the highest amount of resistance to the penicillin G and cefotaxime (100%. mecA gene (encoding methicillin resistance with frequency of 85.18% and aacA-D gene (encoding resistance to aminoglycosides with frequency of 28.33% showed the highest and lowest frequency of antibiotic resistance genes coding in Staphylococcus aureus isolates respectively .   Discussion and conclusion : Notable prevalence of resistant Staphylococcus aureus isolates in community acquired respiratory infections, recommend continuous control necessity to impede the spreading of these bacteria and their infections.  

  8. The Highly Divergent Mitochondrial Genomes Indicate That the Booklouse, Liposcelis bostrychophila (Psocoptera: Liposcelididae) Is a Cryptic Species.

    Science.gov (United States)

    Feng, Shiqian; Yang, Qianqian; Li, Hu; Song, Fan; Stejskal, Václav; Opit, George P; Cai, Wanzhi; Li, Zhihong; Shao, Renfu

    2018-03-02

    The booklouse, Liposcelis bostrychophila is an important storage pest worldwide. The mitochondrial (mt) genome of an asexual strain (Beibei, China) of the L. bostrychophila comprises two chromosomes; each chromosome contains approximate half of the 37 genes typically found in bilateral animals. The mt genomes of two sexual strains of L. bostrychophila , however, comprise five and seven chromosomes, respectively; each chromosome contains one to six genes. To understand mt genome evolution in L. bostrychophila , and whether L. bostrychophila is a cryptic species, we sequenced the mt genomes of six strains of asexual L. bostrychophila collected from different locations in China, Croatia, and the United States. The mt genomes of all six asexual strains of L. bostrychophila have two chromosomes. Phylogenetic analysis of mt genome sequences divided nine strains of L. bostrychophila into four groups. Each group has a distinct mt genome organization and substantial sequence divergence (48.7-87.4%) from other groups. Furthermore, the seven asexual strains of L. bostrychophila , including the published Beibei strain, are more closely related to two other species of booklice, L. paeta and L. sculptilimacula , than to the sexual strains of L. bostrychophila Our results revealed highly divergent mt genomes in the booklouse, L. bostrychophila , and indicate that L. bostrychophila is a cryptic species. Copyright © 2018 Feng et al.

  9. The Highly Divergent Mitochondrial Genomes Indicate That the Booklouse, Liposcelis bostrychophila (Psocoptera: Liposcelididae Is a Cryptic Species

    Directory of Open Access Journals (Sweden)

    Shiqian Feng

    2018-03-01

    Full Text Available The booklouse, Liposcelis bostrychophila is an important storage pest worldwide. The mitochondrial (mt genome of an asexual strain (Beibei, China of the L. bostrychophila comprises two chromosomes; each chromosome contains approximate half of the 37 genes typically found in bilateral animals. The mt genomes of two sexual strains of L. bostrychophila, however, comprise five and seven chromosomes, respectively; each chromosome contains one to six genes. To understand mt genome evolution in L. bostrychophila, and whether L. bostrychophila is a cryptic species, we sequenced the mt genomes of six strains of asexual L. bostrychophila collected from different locations in China, Croatia, and the United States. The mt genomes of all six asexual strains of L. bostrychophila have two chromosomes. Phylogenetic analysis of mt genome sequences divided nine strains of L. bostrychophila into four groups. Each group has a distinct mt genome organization and substantial sequence divergence (48.7–87.4% from other groups. Furthermore, the seven asexual strains of L. bostrychophila, including the published Beibei strain, are more closely related to two other species of booklice, L. paeta and L. sculptilimacula, than to the sexual strains of L. bostrychophila. Our results revealed highly divergent mt genomes in the booklouse, L. bostrychophila, and indicate that L. bostrychophila is a cryptic species.

  10. Cryptic diversity and population genetic structure in the rare, endemic, forest-obligate, slender geckos of the Philippines.

    Science.gov (United States)

    Siler, Cameron D; Dececchi, T Alex; Merkord, Chris L; Davis, Drew R; Christiani, Tony J; Brown, Rafe M

    2014-01-01

    Recent studies of forest lizards in Southeast Asia have highlighted spectacular morphological and cryptic genetic diversity in several poorly known clades. Unfortunately, many of the included species have microhabitat preferences for forested environments, and therefore they are threatened by extensive forest destruction throughout the region. This is particularly true in the Philippines, an archipelago with a strikingly high proportion (84%) of endemic geckos. Abundances inferred from historical museum collections suggests that we are in a critical period where apparent declines in population viability and species' abundance have taken place faster than the growth in our understanding of alpha diversity. This phenomenon is exemplified in the exceedingly rare Philippine slender forest geckos of the genus Pseudogekko. Most of the known species are rarely encountered by field biologists, and species boundaries are unclear; this poor state of knowledge impedes effective conservation measures. Using the first multilocus phylogeny for these taxa, and phylogenetic and population genetic approaches, we elucidate evolutionary lineages and delimit species-level conservation targets in this unique radiation of endemic Philippine geckos. The results support the presence of widespread cryptic diversity in the genus, providing a framework for the re-evaluation of conservation priorities aimed at protecting these rare, forest-obligate species. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Phytochemical Prospection and Modulation of Antibiotic Activity In Vitro by Lippia origanoides H.B.K. in Methicillin Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Humberto Medeiros Barreto

    2014-01-01

    Full Text Available The Lippia origanoides H.B.K. ethanol extract (LOEE and hexane (LOHEX, dichloromethane (LODCM, and ethyl acetate (LOEA fractions were tested for their antimicrobial activity alone or in combination with antibiotics against a methicillin resistant Staphylococcus aureus (MRSA strain. The natural products did not show antimicrobial activity against multidrug resistant strain at the clinically significant concentrations tested. However, a modulatory effect in the antibacterial activity of the neomycin and amikacin was verified when LOEE, LOHEX and LODCM were added to the growth medium at subinhibitory concentrations. A similar modulation was found when the natural products were changed for chlorpromazine, an inhibitor of bacterial efflux pumps, suggesting the involvement of resistance mediated by efflux system in the MRSA tested. The fractions LOHEX and LODCM showed a modulatory activity bigger than their majority compounds (carvacrol, thymol, and naringenin, indicating that this activity is not due to their majority compounds only, but it is probably due to a synergism between their chemical components. These results indicate that L. origanoides H.B.K. can be a source of phytochemicals able to modify the phenotype of resistance to aminoglycosides in MRSA.

  12. Phenotypic Detection of Metallo-Beta-Lactamases in Carbapenem Resistant Acinetobacter baumannii Isolated from Pediatric Patients in Pakistan

    Directory of Open Access Journals (Sweden)

    Muneeza Anwar

    2016-01-01

    Full Text Available Multidrug resistant A. baumannii has emerged as an important and problematic human pathogen as it is the causative agent of several types of infections especially in neonates and immunocompromised patients because they have least capacity to fight against infections. Carbapenems are used as last resort antibiotics for treating these infections but currently resistance against carbapenems due to MBL production is on the rise. The objective of this study was to determine the frequency of antibiotic resistance in A. baumannii and also to compare the efficacy of combined disk test and double disk synergy test for detection of metallo-beta-lactamases. A total of 112 A. baumannii were identified from various clinical samples and antibiotic susceptibility profile was determined by Kirby-Bauer Disk Diffusion method. Out of 112, 66 (58.9% isolates were resistant to both imipenem and meropenem (OXOID. These resistant isolates were tested for carbapenemase production, and 55 (83.3% were carbapenemase producers by Modified Hodge Test. These isolates were further tested for MBL production by combined disk test and double disk synergy test. Out of 66, 49 isolates were positive by both methods, CDT and DDST, and only one isolate was detected as negative (with kappa value = 0.038. All MBL producing strains showed remarkable resistance to cephalosporins, fluoroquinolones, aminoglycosides, and piperacillin/tazobactam (OXOID. The antibiotic resistance was very high in A. baumannii which were isolated from children in Pakistan specially attending a nephrology unit.

  13. Mounting resistance of uropathogens to antimicrobial agents: A retrospective study in patients with chronic bacterial prostatitis relapse.

    Science.gov (United States)

    Stamatiou, Konstantinos; Pierris, Nikolaos

    2017-07-01

    Despite recent progress in the management of chronic bacterial prostatitis (CBP), many cases relapse. Increased drug resistance patterns of responsible bacteria have been proposed as the most probable causative factor. Driven by the limited number of previous studies addressing this topic, we aimed to study whether antibiotic resistance increases in patients with CBP when relapse occurs. A secondary aim of this study was to determine the resistance patterns of responsible bacteria from patients with CBP. The study material consisted of bacterial isolates from urine and/or prostatic secretions obtained from patients with CBP. Bacterial identification was performed by using the Vitek 2 Compact system and susceptibility testing was performed by disc diffusion and/or the Vitek 2 system. Interpretation of susceptibility results was based on Clinical and Laboratory Standards Institute guidelines. A total of 253 samples from patients diagnosed with CBP for the first time (group A) and 137 samples from relapsing patients with a history of CBP and previous antibiotic treatment (group B) were analyzed. A significant reduction in bacterial resistance to the less used antibiotics (TMP-SMX, tetracyclines, aminoglycosides, penicillins, and macrolides) was noted. An increase in resistance to quinolones of many bacteria that cause CBP was also noted with the increase in resistance of enterococcus strains being alarming. Comparison of the resistance profile of CBP-responsible bacteria between samples from first-time-diagnosed patients and samples from relapsing patients revealed notable differences that could be attributed to previous antibiotic treatment.

  14. Risk factors associated with fluoroquinolone-resistant enterococcal urinary tract infections in a tertiary care university hospital in north India.

    Science.gov (United States)

    Banerjee, Tuhina; Anupurba, Shampa

    2016-10-01

    Fluoroquinolone resistance in both Gram-positive and Gram-negative bacteria has increased with the widespread use of fluoroquinolones. Fluoroquinolone resistance in Gram-negative bacilli has been widely studied, though staphylococci and enterococci are also notably resistant. Enterococci being the second most common cause of healthcare-associated urinary tract infections (UTIs) fluoroquinolones are often the drug of choice. This study was undertaken to assess the risk factors associated with fluoroquinolone-resistant enterococcal UTI in a tertiary level health facility in north India. A total of 365 patients with UTI caused by enterococci were studied over a period of two years. Patients with ciprofloxacin-resistant and susceptible UTI were considered as cases and controls, respectively. Resistance profile of the isolates against common antibiotics was studied by minimum inhibitory concentration (MIC) determination. Mechanisms for fluoroquinolone resistance was studied by efflux pump inhibitor activity and multiplex PCR targeting the qnr genes. A total of 204 (55.89%) cases and 161 (44.1%) controls were identified. The fluoroquinolone-resistant isolates were significantly resistant to ampicillin, high strength aminoglycosides and vancomycin. The majority (78%) of the resistant isolates showed efflux pump activity. Treatment in indoor locations, presence of urinary catheters and pregnancy along with recent exposure to antibiotics especially fluoroquinolones, third generation cephalosporins and piperacillin-tazobactam were identified as independent risk factors. Our results showed that fluoroquinolone resistance in enterococcal UTI was largely associated with indoor usage of antibiotics and use of indwelling devices. Knowledge of risk factors is important to curb this emergence of resistance.

  15. A bridge too far: dispersal barriers and cryptic speciation in an Arabian Peninsula grouper (Cephalopholis hemistiktos)

    KAUST Repository

    Priest, Mark; DiBattista, Joseph; McIlwain, Jennifer L.; Taylor, Brett M.; Hussey, Nigel E.; Berumen, Michael L.

    2015-01-01

    Aim: We use genetic and age-based analyses to assess the evidence for a biogeographical barrier to larval dispersal in the yellowfin hind, Cephalopholis hemistiktos, a commercially important species found across the Arabian Peninsula. Location: Red Sea, Gulf of Aden, Gulf of Oman and Arabian Gulf. Methods: Mitochondrial DNA cytochrome-c oxidase subunit-I and nuclear DNA (S7) sequences were obtained for C. hemistiktos sampled throughout its distributional range. Phylogeographical and population-level analyses were used to assess patterns of genetic structure and to identify barriers to dispersal. Concurrently, age-based demographic analyses using otoliths determined differences in growth and longevity between regions. Results: Our analyses revealed significant genetic structure congruent with growth parameter differences observed across sampling sites, suggesting cryptic speciation between populations in the Red Sea and Gulf of Aden versus the Gulf of Oman and Arabian Gulf. Coalescence analyses indicated these two regions have been isolated for > 800,000 years. Main conclusions: Our results indicate historical disruption to gene flow and a contemporary dispersal barrier in the Arabian Sea, which C. hemistiktos larvae are unable to effectively traverse. This provides yet another example of a (cryptic) species with high dispersive potential whose range is delimited by a lack of suitable habitat between locations or an inability to successfully recruit at the range edge. © 2015 John Wiley & Sons Ltd.

  16. A bridge too far: dispersal barriers and cryptic speciation in an Arabian Peninsula grouper (Cephalopholis hemistiktos)

    KAUST Repository

    Priest, Mark

    2015-12-12

    Aim: We use genetic and age-based analyses to assess the evidence for a biogeographical barrier to larval dispersal in the yellowfin hind, Cephalopholis hemistiktos, a commercially important species found across the Arabian Peninsula. Location: Red Sea, Gulf of Aden, Gulf of Oman and Arabian Gulf. Methods: Mitochondrial DNA cytochrome-c oxidase subunit-I and nuclear DNA (S7) sequences were obtained for C. hemistiktos sampled throughout its distributional range. Phylogeographical and population-level analyses were used to assess patterns of genetic structure and to identify barriers to dispersal. Concurrently, age-based demographic analyses using otoliths determined differences in growth and longevity between regions. Results: Our analyses revealed significant genetic structure congruent with growth parameter differences observed across sampling sites, suggesting cryptic speciation between populations in the Red Sea and Gulf of Aden versus the Gulf of Oman and Arabian Gulf. Coalescence analyses indicated these two regions have been isolated for > 800,000 years. Main conclusions: Our results indicate historical disruption to gene flow and a contemporary dispersal barrier in the Arabian Sea, which C. hemistiktos larvae are unable to effectively traverse. This provides yet another example of a (cryptic) species with high dispersive potential whose range is delimited by a lack of suitable habitat between locations or an inability to successfully recruit at the range edge. © 2015 John Wiley & Sons Ltd.

  17. [Analysis of resistant genes of beta-lactam antibiotics from Pseudomonas aeruginosa in pediatric patients].

    Science.gov (United States)

    Dong, Fang; Xu, Xi-wei; Song, Wen-qi; Lü, Ping; Yang, Yong-hong; Shen, Xu-zhuang

    2008-11-18

    To analyze the antibiotic resistance of the Pseudomonas aeruginosa (PA) isolated from pediatric patients and the resistant genes of beta-lactam antibiotics thereof. 146 PA strains were isolated from pediatric patients. Agar dilution method recommended by the Clinical and Laboratory Standards Institute was used to examine the minimum inhibitory concentrations (MICs) of 12 antimicrobial agents, including the penicillins, third and fourth genet ration cephalosporins, carbapenemase, Aztreonam, beta-lactamase inhibitors, quinolones, and aminoglycosides. PCR was used to detect the expression of the genes TEM, SHV, OXA, PER, GES, CTX-M, IMP, VIM, DHA, MIR, FOX, and oprD2. The multi-drug resistance rates against different antibiotic were high among the 146 PA strains. The rates of imipenem and meropenem resistance were 41.1% and 35.6% respectively. Among the 146 PA strains, 46 (31.5%) were positive for the MBL genotype; 38 (82.6%) carried the blaIMP gene, 8 (17.4%) carried the blaVIM gene, and 114 (78.1%) were oprD2 negative. The genes TEM, SHV, OXA, CTX-M, PER, VEB, GES, FOX, MIR, and DHA were not found in all strains. Many PA isolated from pediatric patients carry the genes IMP or VIM and losses oprD2 gene related to the expression of the outer membrane porin OprD2. The loss of the gene oprD2 is essential mechanism of beta-lactam antibiotics resistance in PA.

  18. Identification, antimicrobial resistance and genotypic characterization of Enterococcus spp. isolated in Porto Alegre, Brazil

    Science.gov (United States)

    Bender, Eduardo André; de Freitas, Ana Lúcia Peixoto; Reiter, Keli Cristine; Lutz, Larissa; Barth, Afonso Luís

    2009-01-01

    In the past two decades the members of the genus Enterococcus have emerged as important nosocomial pathogens worldwide. In the present study, we evaluated the antimicrobial resistance and genotypic characteristics of 203 Enterococcus spp. recovered from different clinical sources from two hospitals in Porto Alegre, Rio Grande do Sul, Brazil. The species were identified by conventional biochemical tests and by an automated system. The genetic diversity of E. faecalis presenting high-level aminoglycoside resistance (HLAR) was assessed by pulsed-field gel electrophoresis of chromosomal DNA after SmaI digestion. The E. faecalis was the most frequent specie (93.6%), followed by E. faecium (4.4%). The antimicrobial resistance profile was: 2.5% to ampicillin, 0.5% to vancomycin, 0.5% teicoplanin, 33% to chloramphenicol, 2% to nitrofurantoin, 66.1% to erythromycin, 66.5% to tetracycline, 24.6% to rifampicin, 30% to ciprofloxacin and 87.2% to quinupristin-dalfopristin. A total of 10.3% of the isolates proved to be HLAR to both gentamicin and streptomycin (HLR-ST/GE), with 23.6% resistant only to gentamicin (HLR-GE) and 37.4% only to streptomycin (HLR-ST). One predominant clonal group was found among E. faecalis HLR-GE/ST. The prevalence of resistance among beta-lactam antibiotics and glycopeptides was very low. However, in this study there was an increased number of HLR Enterococcus which may be spreading intra and inter-hospital. PMID:24031416

  19. Effects of salicylates and aminoglycosides on spontaneous otoacoustic emissions in the Tokay gecko.

    Science.gov (United States)

    Stewart, C E; Hudspeth, A J

    2000-01-04

    The high sensitivity and sharp frequency discrimination of hearing depend on mechanical amplification in the cochlea. To explore the basis of this active process, we examined the pharmacological sensitivity of spontaneous otoacoustic emissions (SOAEs) in a lizard, the Tokay gecko. In a quiet environment, each ear produced a complex but stable pattern of emissions. These SOAEs were reversibly modulated by drugs that affect mammalian otoacoustic emissions, the salicylates and the aminoglycoside antibiotics. The effect of a single i.p. injection of sodium salicylate depended on the initial power of the emissions: ears with strong control SOAEs displayed suppression at all frequencies, whereas those with weak control emissions showed enhancement. Repeated oral administration of acetylsalicylic acid reduced all emissions. Single i.p. doses of gentamicin or kanamycin suppressed SOAEs below 2.6 kHz, while modulating those above 2.6 kHz in either of two ways. For ears whose emission power at 2.6-5.2 kHz encompassed more than half of the total, individual emissions displayed facilitation as great as 35-fold. For the remaining ears, emissions dropped to as little as one-sixth of their initial values. The similarity of the responses of reptilian and mammalian cochleas to pharmacological intervention provides further evidence for a common mechanism of cochlear amplification.

  20. Pure tone audiograms and possible aminoglycoside-induced hearing loss in belugas (Delphinapterus leucas)

    Science.gov (United States)

    Finneran, James J.; Carder, Donald A.; Dear, Randall; Belting, Traci; McBain, Jim; Dalton, Les; Ridgway, Sam H.

    2005-06-01

    A behavioral response paradigm was used to measure pure-tone hearing sensitivities in two belugas (Delphinapterus leucas). Tests were conducted over a 20-month period at the Point Defiance Zoo and Aquarium, in Tacoma, WA. Subjects were two males, aged 8-10 and 9-11 during the course of the study. Subjects were born in an oceanarium and had been housed together for all of their lives. Hearing thresholds were measured using a modified up/down staircase procedure and acoustic response paradigm where subjects were trained to produce audible responses to test tones and to remain quiet otherwise. Test frequencies ranged from approximately 2 to 130 kHz. Best sensitivities ranged from approximately 40 to 50 dB re 1 μPa at 50-80 kHz and 30-35 kHz for the two subjects. Although both subjects possessed traditional ``U-shaped'' mammalian audiograms, one subject exhibited significant high-frequency hearing loss above 37 kHz compared to previously published data for belugas. Hearing loss in this subject was estimated to approach 90 dB for frequencies above 50 kHz. Similar ages, ancestry, and environmental conditions between subjects, but a history of ototoxic drug administration in only one subject, suggest that the observed hearing loss was a result of the aminoglycoside antibiotic amikacin. .

  1. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    Purdy Drew, Kirstin R.; Sanders, Lori K.; Culumber, Zachary W.; Zribi, Olena; Wong, Gerard C.L.

    2009-01-01

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  2. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    Drew, K.R.Purdy; Sanders, L.K.; Culumber, Z.W.; Zribi, O.; Wong, G.C.L.

    2009-01-01

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers

  3. Predominance of carbapenem-resistant Pseudomonas aeruginosa isolates carrying blaIMP and blaVIM metallo-β-lactamases in a major hospital in Costa Rica.

    Science.gov (United States)

    Toval, Francisco; Guzmán-Marte, Anel; Madriz, Vivian; Somogyi, Teresita; Rodríguez, César; García, Fernando

    2015-01-01

    This study aimed to assess the molecular basis of the resistance to carbapenems in clinical isolates of Pseudomonas aeruginosa recovered from a tertiary-level health facility in San José, Costa Rica. A total of 198 non-duplicated isolates were evaluated for their susceptibility to β-lactams, aminoglycosides and fluoroquinolones. The production of metallo-β-lactamases (MBLs), the presence of MBL encoding genes (blaIMP, blaVIM and blaGIM-1) and the occurrence of these genes within class 1 integrons were investigated. In addition, an ERIC2 PCR fingerprinting method was used to elucidate the distribution of the detected MBL genes within the strain collection. Of the 198 isolates tested, 125 (63.1 %) were categorized as carbapenem-resistant. The majority (88.8 %) of the carbapemen-resistant isolates also showed resistance to ceftazidime, cefepime, aztreonam, ticarcillin/clavulanic acid, amikacin, gentamicin, tobramycin, ciprofloxacin and gatifloxacin. Among the carbapenem-resistant isolates, 102 (81.6 %) showed MBL activity. Strikingly, both blaIMP and blaVIM genes were simultaneously detected in most (94.1 %) of the 102 MBL producers. Five carbapenem-resistant MBL producers were positive only for blaIMP genes. Almost 70 % of the isolates examined harboured the intI1 gene, accompanied by the sul1 and qacEΔ1 genes in 136 (99 %) and 122 (89 %) isolates, respectively. The majority (94.4 %) of the carbapenem-resistant isolates carried the intI1 gene, in contrast to 26 % of the carbapenem-susceptible isolates. Ninety-three out of 96 (96.9 %) isolates carrying both blaIMP and blaVIM genes also harboured the intI1, sul1 and qacEΔ1 genes. Gene cassettes from carbapenem-susceptible and MBL-negative carbapenem-resistant isolates encoded aminoglycoside-resistance enzymes (aadA2, aadA4 and aadA6) as well as orfD and qacF genes. RAPD analysis distributed 126 of the isolates in 29 clusters. Eighty of the 90 blaIMP (+) blaVIM (+) isolates were sorted into 16

  4. Cyanomargarita gen. nov. (Nostocales, Cyanobacteria): convergent evolution resulting in a cryptic genus.

    Science.gov (United States)

    Shalygin, Sergei; Shalygina, Regina; Johansen, Jeffrey R; Pietrasiak, Nicole; Berrendero Gómez, Esther; Bohunická, Markéta; Mareš, Jan; Sheil, Christopher A

    2017-08-01

    Two populations of Rivularia-like cyanobacteria were isolated from ecologically distinct and biogeographically distant sites. One population was from an unpolluted stream in the Kola Peninsula of Russia, whereas the other was from a wet wall in the Grand Staircase-Escalante National Monument, a desert park-land in Utah. Though both were virtually indistinguishable from Rivularia in field and cultured material, they were both phylogenetically distant from Rivularia and the Rivulariaceae based on both 16S rRNA and rbcLX phylogenies. We here name the new cryptic genus Cyanomargarita gen. nov., with type species C. melechinii sp. nov., and additional species C. calcarea sp. nov. We also name a new family for these taxa, the Cyanomargaritaceae. © 2017 Phycological Society of America.

  5. Culture and Next-generation sequencing-based drug susceptibility testing unveil high levels of drug-resistant-TB in Djibouti: results from the first national survey.

    Science.gov (United States)

    Tagliani, Elisa; Hassan, Mohamed Osman; Waberi, Yacine; De Filippo, Maria Rosaria; Falzon, Dennis; Dean, Anna; Zignol, Matteo; Supply, Philip; Abdoulkader, Mohamed Ali; Hassangue, Hawa; Cirillo, Daniela Maria

    2017-12-15

    Djibouti is a small country in the Horn of Africa with a high TB incidence (378/100,000 in 2015). Multidrug-resistant TB (MDR-TB) and resistance to second-line agents have been previously identified in the country but the extent of the problem has yet to be quantified. A national survey was conducted to estimate the proportion of MDR-TB among a representative sample of TB patients. Sputum was tested using XpertMTB/RIF and samples positive for MTB and resistant to rifampicin underwent first line phenotypic susceptibility testing. The TB supranational reference laboratory in Milan, Italy, undertook external quality assurance, genotypic testing based on whole genome and targeted-deep sequencing and phylogenetic studies. 301 new and 66 previously treated TB cases were enrolled. MDR-TB was detected in 34 patients: 4.7% of new and 31% of previously treated cases. Resistance to pyrazinamide, aminoglycosides and capreomycin was detected in 68%, 18% and 29% of MDR-TB strains respectively, while resistance to fluoroquinolones was not detected. Cluster analysis identified transmission of MDR-TB as a critical factor fostering drug resistance in the country. Levels of MDR-TB in Djibouti are among the highest on the African continent. High prevalence of resistance to pyrazinamide and second-line injectable agents have important implications for treatment regimens.

  6. Feed additives shift gut microbiota and enrich antibiotic resistance in swine gut.

    Science.gov (United States)

    Zhao, Yi; Su, Jian-Qiang; An, Xin-Li; Huang, Fu-Yi; Rensing, Christopher; Brandt, Kristian Koefoed; Zhu, Yong-Guan

    2018-04-15

    Antibiotic resistance genes (ARGs) are emerging environmental contaminants posing a threat to public health. Antibiotics and metals are widely used as feed additives and could consequently affect ARGs in swine gut. In this study, high-throughput quantitative polymerase chain reaction (HT-qPCR) based ARG chip and next-generation 16S rRNA gene amplicon sequencing data were analyzed using multiple statistical approaches to profile the antibiotic resistome and investigate its linkages to antibiotics and metals used as feed additives and to the microbial community composition in freshly collected swine manure samples from three large-scale Chinese pig farms. A total of 146 ARGs and up to 1.3×10 10 total ARG copies per gram of swine feces were detected. ARGs conferring resistance to aminoglycoside, macrolide-lincosamide-streptogramin B (MLSB) and tetracycline were dominant in pig gut. Total abundance of ARGs was positively correlated with in-feed antibiotics, microbial biomass and abundance of mobile genetic elements (MGEs) (Padditives and community composition (16.5%). These results suggest that increased levels of in-feed additives could aggravate the enrichment of ARGs and MGEs in swine gut. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Multivariable Analysis of the Association Between Antimicrobial Use and Antimicrobial Resistance in Escherichia coli Isolated from Apparently Healthy Pigs in Japan.

    Science.gov (United States)

    Makita, Kohei; Goto, Masaki; Ozawa, Manao; Kawanishi, Michiko; Koike, Ryoji; Asai, Tetsuo; Tamura, Yutaka

    2016-01-01

    The objective of this study was to investigate the association between antimicrobial agent use and antimicrobial resistance in Escherichia coli isolated from healthy pigs using data from 2004 to 2007 in the Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM). Fecal E. coli isolates from 250 pigs (one isolate each from a pig per farm) were examined for antimicrobial resistance. Information on the use of antimicrobials within preceding 6 months and types of farms recorded in JVARM was collected and statistically analyzed against the resistance patterns. In the univariate analysis, associations between both therapeutic and feed additive use of antimicrobials, and resistance to dihydrostreptomycin, gentamicin, kanamycin, ampicillin, cefazolin, ceftiofur, oxytetracycline, chloramphenicol, trimethoprim, nalidixic acid, enrofloxacin, colistin, and bicozamycin, and husbandry factors were investigated. In multivariable analysis, generalized estimating equations were used to control geographical intraclass correlation. Confounding for structurally unrelated associations was tested using generalized linear models. The results suggested direct and cross selections in the associations between use of aminoglycosides in reproduction farms and resistance to kanamycin, use of tetracyclines in larger farms and resistance to oxytetracycline, use of beta-lactams and resistance to ampicillin, use of phenicols and resistance to chloramphenicol, and use of fluoroquinolones and resistance to nalidixic acid and enrofloxacin. Coselection was suggested in the use of tetracyclines and chloramphenicol resistance. The associations between use of beta-lactams and dihydrostreptomycin resistance, use of macrolides and ampicillin and oxytetracycline resistance, and use of colistin and kanamycin resistance were significant, but were confounded by the simultaneous use of homologous antimicrobials.

  8. Genetic complexity of fusidic acid-resistant small colony variants (SCV in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Jonas Lannergård

    Full Text Available FusE mutants are fusidic acid-resistant small colony variants (SCVs of Staphylococcus aureus that can be selected with aminoglycosides. All FusE SCVs have mutations in rplF, encoding ribosomal protein L6. However, individual FusE mutants including some with the same mutation in rplF display auxotrophy for either hemin or menadione, suggesting that additional mutations are involved. Here we show that FusE SCVs can be divided into three genetic sub-groups and that some carry an additional mutation, in one of the genes required for hemin biosynthesis, or in one of the genes required for menadione biosynthesis. Reversion analysis and genome sequencing support the hypothesis that these combinations of mutations in the rplF, hem, and/or men genes can account for the SCV and auxotrophic phenotypes of FusE mutants.

  9. Resistência a β-lactâmicos em Acinetobacter spp isolados de efluente hospitalar no sul do Brasil Resistance to β-lactams among Acinetobacter spp isolated from hospital sewage in southern Brazil

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    Carolina de Souza Gusatti

    2009-04-01

    Full Text Available Acinetobacter spp é um importante patógeno causador de infecções nosocomiais que acomete pacientes imunocomprometidos e capaz de adquirir resistência a antimicrobianos com facilidade. Os esgotos hospitalares são importantes disseminadores de genes de resistência a antimicrobianos para a microbiota ambiental. Neste contexto, 30 cepas de Acinetobacter spp provenientes de efluente de um hospital em Porto Alegre, RS, foram analisados quanto ao perfil de susceptibilidade a β-lactamases, quinolonas e aminoglicosídeos através de antibiograma e testes de triagem para metalo beta-lactamases e β-lactamases de espectro estendido. O perfil encontrado revela cepas multi-resistentes e que mecanismos de resistência como a produção de β-lactamases de espectro estendido e bombas de efluxo podem estar presentes nesses isolados.Acinetobacter spp is an important pathogen that is responsible for nosocomial infections affecting immunocompromised patients, and it can easily acquire resistance to antimicrobial agents. Hospital sewage is an important means for disseminating genes for resistance to antimicrobial agents, to the microbiota of the environment. Within this context, 30 strains of Acinetobacter spp from the sewage of a hospital in Porto Alegre, Rio Grande do Sul, were analyzed regarding their profile of susceptibility to β-lactams, quinolones and aminoglycosides, by means of an antibiogram and tests to screen for metallo-β-lactamases and extended-spectrum β-lactamases. The profile obtained revealed the presence of multidrug-resistant strains and showed that resistance mechanisms such as the production of extended-spectrum β-lactamases and efflux pumps may be present in these strains.

  10. Early events in speciation: Cryptic species of Drosophila aldrichi.

    Science.gov (United States)

    Castro Vargas, Cynthia; Richmond, Maxi Polihronakis; Ramirez Loustalot Laclette, Mariana; Markow, Therese Ann

    2017-06-01

    Understanding the earliest events in speciation remains a major challenge in evolutionary biology. Thus identifying species whose populations are beginning to diverge can provide useful systems to study the process of speciation. Drosophila aldrichi , a cactophilic fruit fly species with a broad distribution in North America, has long been assumed to be a single species owing to its morphological uniformity. While previous reports either of genetic divergence or reproductive isolation among different D. aldrichi strains have hinted at the existence of cryptic species, the evolutionary relationships of this species across its range have not been thoroughly investigated. Here we show that D. aldrichi actually is paraphyletic with respect to its closest relative, Drosophila wheeleri , and that divergent D. aldrichi lineages show complete hybrid male sterility when crossed. Our data support the interpretation that there are at least two species of D. aldrichi, making these flies particularly attractive for studies of speciation in an ecological and geographical context.

  11. Diagnosis of Familial Wolf-Hirschhorn Syndrome due to a Paternal Cryptic Chromosomal Rearrangement by Conventional and Molecular Cytogenetic Techniques

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    Carlos A. Venegas-Vega

    2013-01-01

    Full Text Available The use of conventional cytogenetic techniques in combination with fluorescent in situ hybridization (FISH and single-nucleotide polymorphism (SNP microarrays is necessary for the identification of cryptic rearrangements in the diagnosis of chromosomal syndromes. We report two siblings, a boy of 9 years and 9 months of age and his 7-years- and 5-month-old sister, with the classic Wolf-Hirschhorn syndrome (WHS phenotype. Using high-resolution GTG- and NOR-banding karyotypes, as well as FISH analysis, we characterized a pure 4p deletion in both sibs and a balanced rearrangement in their father, consisting in an insertion of 4p material within a nucleolar organizing region of chromosome 15. Copy number variant (CNV analysis using SNP arrays showed that both siblings have a similar size of 4p deletion (~6.5 Mb. Our results strongly support the need for conventional cytogenetic and FISH analysis, as well as high-density microarray mapping for the optimal characterization of the genetic imbalance in patients with WHS; parents must always be studied for recognizing cryptic balanced chromosomal rearrangements for an adequate genetic counseling.

  12. Bacteremia and candidemia in hematological malignancies

    DEFF Research Database (Denmark)

    Bruun, B; Bangsborg, Jette Marie; Hovgaard, D

    1988-01-01

    of coagulase-negative staphylococci was higher in the latter period while that of Staphylococcus aureus was lower. Of 67 strains of Enterobacteriaceae tested for an aminoglycoside, 6% were found to be resistant, whereas 8% of 48 Enterobacteriaceae strains were found to be cefotaxime resistant. Methicillin...

  13. Bacterial Aetiology and Antibiotic Resistance Pattern of Community-Acquired Urinary Tract Infections in Children in a Tertiary Care Hospital in Bangladesh

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    Lazina Sharmin

    2017-09-01

    Full Text Available Background: Urinary tract infections (UTIs in children are among the most common bacterial infections. Community-acquired urinary tract infections (CAUTI are often treated empirically with broad-spectrum antibiotics. Pattern of aetiologic agents and their antibiotic sensitivity may vary according to geographical and regional location. So, knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Objectives: To determine the common bacterial aetiologies of CAUTIs and their antibiotic resistance patterns in a tertiary care hospital, Savar. Materials and Methods: This cross-sectional descriptive study was conducted at Enam Medical College Hospital, Savar from May 2016 to April 2017. We collected clean-catch mid-stream urine samples from 257 patients having clinical diagnosis of UTI and submitted to the clinical microbiology laboratory for culture and sensitivity. Results: A total of 120 (46.7% samples were positive for bacterial growth. Escherichia coli (79% was the most common pathogen, followed by Klebsiella spp. (14%. Bacterial isolates showed high prevalence of resistance to multiple antibiotics. Resistance against amoxicillin/clavulanic acid, co-trimoxazole and ciprofloxacin was higher compared to newer quinolones and aminoglycosides. Conclusion: Esch. coli and Klebsiella spp. were the predominant bacterial pathogens. The resistance pattern to commonly prescribed antibiotics was quite high and alarming.

  14. Molecular evidence of cryptic speciation in the "cosmopolitan" excavating sponge Cliona celata (Porifera, Clionaidae).

    Science.gov (United States)

    Xavier, J R; Rachello-Dolmen, P G; Parra-Velandia, F; Schönberg, C H L; Breeuwer, J A J; van Soest, R W M

    2010-07-01

    Over the past several decades molecular tools have shown an enormous potential to aid in the clarification of species boundaries in the marine realm, particularly in morphologically simple groups. In this paper we report a case of cryptic speciation in an allegedly cosmopolitan and ecologically important species-the excavating sponge Cliona celata (Clionaidae, Hadromerida). In the Northeast Atlantic and Mediterranean C. celata displays a discontinuous distribution of its putative growth stages (boring, encrusting, and massive) leading us to investigate its specific status. Phylogenetic reconstructions of mitochondrial (COI, Atp8) and nuclear (28S) gene fragments revealed levels of genetic diversity and divergence compatible with interspecific relationships. We therefore demonstrate C. celata as constituting a species complex comprised of at least four morphologically indistinct species, each showing a far more restricted distribution: two species on the Atlantic European coasts and two on the Mediterranean and adjacent Atlantic coasts (Macaronesian islands). Our results provide further confirmation that the different morphotypes do indeed constitute either growth stages or ecologically adapted phenotypes as boring and massive forms were found in two of the four uncovered species. We additionally provide an overview of the cases of cryptic speciation which have been reported to date within the Porifera, and highlight how taxonomic crypsis may confound scientific interpretation and hamper biotechnological advancement. Our work together with previous studies suggests that overconservative systematic traditions but also morphological stasis have led to genetic complexity going undetected and that a DNA-assisted taxonomy may play a key role in uncovering the hidden diversity in this taxonomic group. Copyright 2010 Elsevier Inc. All rights reserved.

  15. Microflora of conjunctiva in children and its sensitivity and resistance to antibacterial drugs

    Directory of Open Access Journals (Sweden)

    T. N. Vorontsova

    2014-07-01

    Full Text Available Purpose: Investigation of microflora of conjunctiva and its resistance to antibacterial drugs in healthy children and patients with various inflammatory eye diseases.Methods: We examined 402 children (421 eyes in the age from 1 month till 17 years: 62 healthy children (70 eyes and 340 pa- tients with different inflammatory diseases of anterior segment of eye (351 eyes. the smear was done in all children for plating and definition of sensitivity of microflora to antibacterial drugs by method of diffusion to agar.Results: the plating was positive even in 72.9% of healthy children who entered the hospital for the planned surgery. Most often we revealed Staphylococcus epidermidis (44.3%, Staphylococcus aureus (12.8%, Streptococcus faecalis (5.7% and Enterobacter (2.9%. In children with inflammatory diseases Staphylococcus epidermidis and Staphylococcus aureus (62.6% were found fre- quently. the analysis of data showed high level of resistance of all microflora to aminoglycosides (neomycin 37.8% and tobramycin 32.7% and chloramphenicol — 37.1%. the lowest resistance of all microflora was registered to levofloxacin (11.1% and ciprofloxacin (10.5%. In gram-negative microflora we revealed the maximal sensitivity to ciprofloxacin, in gram-positive — to levofloxacin.We detected the maximal resistance of microflora to ampicillin (66.1%, and minimal — to cephalosporines (4.5% among the antibiotics of systemic application.Conclusion: the findings allow us to recommend drops containing levofloxacin (Signicef for clinical practice in pediatric ophthalmology. 

  16. Microflora of conjunctiva in children and its sensitivity and resistance to antibacterial drugs

    Directory of Open Access Journals (Sweden)

    T. N. Vorontsova

    2012-01-01

    Full Text Available Purpose: Investigation of microflora of conjunctiva and its resistance to antibacterial drugs in healthy children and patients with various inflammatory eye diseases.Methods: We examined 402 children (421 eyes in the age from 1 month till 17 years: 62 healthy children (70 eyes and 340 pa- tients with different inflammatory diseases of anterior segment of eye (351 eyes. the smear was done in all children for plating and definition of sensitivity of microflora to antibacterial drugs by method of diffusion to agar.Results: the plating was positive even in 72.9% of healthy children who entered the hospital for the planned surgery. Most often we revealed Staphylococcus epidermidis (44.3%, Staphylococcus aureus (12.8%, Streptococcus faecalis (5.7% and Enterobacter (2.9%. In children with inflammatory diseases Staphylococcus epidermidis and Staphylococcus aureus (62.6% were found fre- quently. the analysis of data showed high level of resistance of all microflora to aminoglycosides (neomycin 37.8% and tobramycin 32.7% and chloramphenicol — 37.1%. the lowest resistance of all microflora was registered to levofloxacin (11.1% and ciprofloxacin (10.5%. In gram-negative microflora we revealed the maximal sensitivity to ciprofloxacin, in gram-positive — to levofloxacin.We detected the maximal resistance of microflora to ampicillin (66.1%, and minimal — to cephalosporines (4.5% among the antibiotics of systemic application.Conclusion: the findings allow us to recommend drops containing levofloxacin (Signicef for clinical practice in pediatric ophthalmology. 

  17. Antimicrobial resistance and resistance genes in Salmonella strains isolated from broiler chickens along the slaughtering process in China.

    Science.gov (United States)

    Zhu, Yuanting; Lai, Haimei; Zou, Likou; Yin, Sheng; Wang, Chengtao; Han, Xinfeng; Xia, Xiaolong; Hu, Kaidi; He, Li; Zhou, Kang; Chen, Shujuan; Ao, Xiaolin; Liu, Shuliang

    2017-10-16

    A total of 189 Salmonella isolates were recovered from 627 samples which were collected from cecal contents of broilers, chicken carcasses, chicken meat after cutting step and frozen broiler chicken products along the slaughtering process at a slaughterhouse in Sichuan province of China. The Salmonella isolates were subjected to antimicrobial susceptibility testing to 10 categories of antimicrobial agents using the Kirby-Bauer disk diffusion method. Those antibiotics-resistant isolates were further investigated for the occurrence of resistance genes, the presence of class 1 integron as well as the associated gene cassettes, and the mutations within the gyrA and parC genes. Consequently, the prevalence of Salmonella was 30.14% (47.96% for cecal content, 18.78% for chicken carcasses, 31.33% for cutting meat and 14.00% for frozen meat, respectively). The predominant serotypes were S. Typhimurium (15.34%) and S. Enteritidis (69.84%). High resistance rates to the following drugs were observed: nalidixic acid (99.5%), ampicillin (87.8%), tetracycline (51.9%), ciprofloxacin (48.7%), trimethoprim/sulfamethoxazole (48.1%), and spectinomycin (34.4%). Antimicrobial resistance profiling showed that 60.8% of isolates were multidrug resistant (MDR), and MDR strains increased from 44.7% to 78.6% along the slaughtering line. 94.6% (n=157) of beta-lactam-resistant isolates harbored at least one resistance gene of bla TEM or bla CTX-M . The relatively low prevalence of aminoglycoside resistance genes (aac(3)-II, aac(3)-IV, and ant(2″)-I) was found in 49 (66.2%) of antibiotic-resistant isolates. The tetracycline resistance genes (tet(A), tet(B), tet(C), and tet(G) and sulfonamide resistance genes (sul1, sul2, and sul3) were identified in 84 (85.7%) and 89 (97.8%) antibiotic-resistant isolates respectively. floR was identified in 44 (97.8%) florfenicol-resistant isolates. Class 1 integron was detected in 37.4% (n=43) of the MDR isolates. Two different gene cassettes, bla OXA-30 -aad

  18. Antibiotic Resistance Genetic Markers and Integrons in White Soft Cheese: Aspects of Clinical Resistome and Potentiality of Horizontal Gene Transfer.

    Science.gov (United States)

    de Paula, Ana Caroline L; Medeiros, Julliane D; de Azevedo, Analice C; de Assis Chagas, Jéssica M; da Silva, Vânia L; Diniz, Cláudio G

    2018-02-19

    Antibiotic resistance poses an important threat to global public health and has become a challenge to modern medicine. The occurrence of antibiotic-resistant bacteria in a broad range of foods has led to a growing concern about the impact that food may have as a reservoir of antibiotic resistance genes. Considering Minas Frescal Cheese (MFC)-a typical Brazilian white soft cheese-and its economic and cultural values, in this study, medically relevant antimicrobial-resistance genetic markers (AR genes) were screened, and the occurrence of integrons were evaluated in manufactured MFC using culture-independent approaches. Through a fingerprinting analysis, the tested MFCs were brand-clustered, indicating reproducibility along the production chain. A common core of resistance markers in all brands evaluated and related antimicrobials such as β-lactams, tetracyclines, quinolones, and sulfonamide was detected. Several other markers, including efflux pumps and aminoglycosides-resistance were distributed among brands. Class 1 and 2 integrons were observed, respectively, in 77% and 97% of the samples. The presence of AR genes is of special interest due to their clinical relevance. Taken together, the data may suggest that the production chain of MFC might contribute to the spread of putative drug-resistant bacteria, which could greatly impact human health. Furthermore, detection of class 1 and class 2 integrons in MFC has led to discussions about resistance gene spread in this traditional cheese, providing evidence of potential horizontal transfer of AR genes to human gut microbiota.

  19. Antibiotic Resistance Genetic Markers and Integrons in White Soft Cheese: Aspects of Clinical Resistome and Potentiality of Horizontal Gene Transfer

    Directory of Open Access Journals (Sweden)

    Ana Caroline L. de Paula

    2018-02-01

    Full Text Available Antibiotic resistance poses an important threat to global public health and has become a challenge to modern medicine. The occurrence of antibiotic-resistant bacteria in a broad range of foods has led to a growing concern about the impact that food may have as a reservoir of antibiotic resistance genes. Considering Minas Frescal Cheese (MFC—a typical Brazilian white soft cheese—and its economic and cultural values, in this study, medically relevant antimicrobial-resistance genetic markers (AR genes were screened, and the occurrence of integrons were evaluated in manufactured MFC using culture-independent approaches. Through a fingerprinting analysis, the tested MFCs were brand-clustered, indicating reproducibility along the production chain. A common core of resistance markers in all brands evaluated and related antimicrobials such as β-lactams, tetracyclines, quinolones, and sulfonamide was detected. Several other markers, including efflux pumps and aminoglycosides-resistance were distributed among brands. Class 1 and 2 integrons were observed, respectively, in 77% and 97% of the samples. The presence of AR genes is of special interest due to their clinical relevance. Taken together, the data may suggest that the production chain of MFC might contribute to the spread of putative drug-resistant bacteria, which could greatly impact human health. Furthermore, detection of class 1 and class 2 integrons in MFC has led to discussions about resistance gene spread in this traditional cheese, providing evidence of potential horizontal transfer of AR genes to human gut microbiota.

  20. Ecological niche modelling and nDNA sequencing support a new, morphologically cryptic beetle species unveiled by DNA barcoding.

    Science.gov (United States)

    Hawlitschek, Oliver; Porch, Nick; Hendrich, Lars; Balke, Michael

    2011-02-09

    DNA sequencing techniques used to estimate biodiversity, such as DNA barcoding, may reveal cryptic species. However, disagreements between barcoding and morphological data have already led to controversy. Species delimitation should therefore not be based on mtDNA alone. Here, we explore the use of nDNA and bioclimatic modelling in a new species of aquatic beetle revealed by mtDNA sequence data. The aquatic beetle fauna of Australia is characterised by high degrees of endemism, including local radiations such as the genus Antiporus. Antiporus femoralis was previously considered to exist in two disjunct, but morphologically indistinguishable populations in south-western and south-eastern Australia. We constructed a phylogeny of Antiporus and detected a deep split between these populations. Diagnostic characters from the highly variable nuclear protein encoding arginine kinase gene confirmed the presence of two isolated populations. We then used ecological niche modelling to examine the climatic niche characteristics of the two populations. All results support the status of the two populations as distinct species. We describe the south-western species as Antiporus occidentalis sp.n. In addition to nDNA sequence data and extended use of mitochondrial sequences, ecological niche modelling has great potential for delineating morphologically cryptic species.

  1. Cryptic species in the nuisance midge Polypedilum nubifer (Skuse (Diptera: Chironomidae) and the status of Tripedilum Kieffer.

    Science.gov (United States)

    Cranston, Peter S; Martin, Jon; Spies, Martin

    2016-02-15

    Polypedilum nubifer (Skuse, 1889), originally described from Australia, is an apparently widespread species of Chironomidae (Diptera) that can attain nuisance densities in some eutrophic water bodies. Appropriate management depends upon the identity and ability to distinguish from potential cryptic taxa. A morphological study of larvae, pupae and adults of both sexes confirmed P. nubifer as widely distributed and frequently abundant, but also revealed two previously cryptic species of limited distribution in northern Australia. These species are described as new and illustrated in all stages here. Polypedilum quasinubifer Cranston sp. n. is described from north-west Queensland, Australia and also from Thailand and Singapore. Polypedilum paranubifer Cranston sp. n. is known only from retention ponds of a uranium mine in Northern Territory, Australia. Unusual morphological features of P. nubifer including alternate Lauterborn organs on the larval antenna, cephalic tubules on the pupa and frontal tubercles on the adult head are present in both new species as well. Newly slide-mounted types of Polypedilum pelostolum Kieffer, 1912 (lectotype designated here) confirm synonymy to Chironomus nubifer Skuse, 1889, examined also as newly-slide mounted types. Reviewed plus new evidence does not support recognition of Tripedilum Kieffer, 1921 as a separate taxon; therefore, Tripedilum is returned to junior synonymy with Polypedilum s. str.

  2. Cryptic extinction of a common Pacific lizard Emoia impar (Squamata, Scincidae) from the Hawaiian Islands.

    Science.gov (United States)

    Fisher, Robert; Ineich, Ivan

    2012-01-01

    Most documented declines of tropical reptiles are of dramatic or enigmatic species. Declines of widespread species tend to be cryptic. The early (1900s) decline and extinction of the common Pacific skink Emoia impar from the Hawaiian Islands is documented here through an assessment of literature, museum vouchers and recent fieldwork. This decline appears contemporaneous with the documented declines of invertebrates and birds across the Hawaiian Islands. A review of the plausible causal factors indicates that the spread of the introduced big-headed ant Pheidole megacephala is the most likely factor in this lizard decline. The introduction and spread of a similar skink Lampropholis delicata across the islands appears to temporally follow the decline of E. impar, although there is no evidence of competition between these species. It appears that L. delicata is spreading to occupy the niche vacated by the extirpated E. impar. Further confusion exists because the skink E. cyanura, which is very similar in appearance to E. impar, appears to have been introduced to one site within a hotel on Kaua'i and persisted as a population at that site for approximately 2 decades (1970s–1990s) but is now also extirpated. This study highlights the cryptic nature of this early species extinction as evidence that current biogeographical patterns of non-charismatic or enigmatic reptiles across the Pacific may be the historical result of early widespread invasion by ants. Conservation and restoration activities for reptiles in the tropical Pacific should consider this possibility and evaluate all evidence prior to any implementation.

  3. A decade-long commitment to antimicrobial resistance surveillance in Portugal

    Directory of Open Access Journals (Sweden)

    Catarina Moreira Marinho

    2016-10-01

    Full Text Available Antimicrobial resistance (AMR is a worldwide problem with serious health and economic repercussions. Since the 1940s, underuse, overuse, and misuse of antibiotics have had a significant environmental downside. Large amounts of antibiotics not fully metabolized after use in human and veterinary medicine, and other applications, are annually released into the environment. The result has been the development and dissemination of antibiotic-resistant bacteria due to many years of selective pressure. Surveillance of AMR provides important information that helps in monitoring and understanding how resistance mechanisms develop and disseminate within different environments. Surveillance data is needed to inform clinical therapy decisions, to guide policy proposals, and to assess the impact of action plans to fight AMR. The Functional Genomics and Proteomics Unit, based at the University of Trás-os-Montes and Alto Douro (UTAD in Vila Real, Portugal, has recently completed 10 years of research surveying AMR in bacteria, mainly commensal indicator bacteria such as enterococci and Escherichia coli from the microbiota of different animals. Samples from more than 75 different sources have been accessed, from humans to food-producing animals, pets, and wild animals. The typical microbiological workflow involved phenotypic studies followed by molecular approaches. Throughout the decade, 4,017 samples were collected and over 5,000 bacterial isolates obtained. High levels of AMR to several antimicrobial classes have been reported, including to β-lactams, glycopeptides, tetracyclines, aminoglycosides, sulphonamides and quinolones. Multi-resistant strains, some relevant to human and veterinary medicine like extended-spectrum β-lactamase-producing E. coli and vancomycin-resistant enterococci, have been repeatedly isolated even in non-synanthropic animal species. Of particular relevance are reports of AMR bacteria in wildlife from natural reserves and endangered

  4. Analysis of triclosan-selected Salmonella enterica mutants of eight serovars revealed increased aminoglycoside susceptibility and reduced growth rates.

    Directory of Open Access Journals (Sweden)

    Ulrike Rensch

    Full Text Available The biocide triclosan (TRC is used in a wide range of household, personal care, veterinary, industrial and medical products to control microbial growth. This extended use raises concerns about a possible association between the application of triclosan and the development of antibiotic resistance. In the present study we determined triclosan mutant prevention concentrations (MPC for Salmonella enterica isolates of eight serovars and investigated selected mutants for their mechanisms mediating decreased susceptibility to triclosan. MPCTRC values were 8-64-fold higher than MIC values and ranged between 1-16 µg/ml. The frequencies at which mutants were selected varied between 1.3 x 10(-10-9.9 x 10(-11. Even if MIC values of mutants decreased by 3-7 dilution steps in the presence of the efflux pump inhibitor Phe-Arg-β-naphtylamide, only minor changes were observed in the expression of genes encoding efflux components or regulators, indicating that neither the major multidrug efflux pump AcrAB-TolC nor AcrEF are up-regulated in triclosan-selected mutants. Nucleotide sequence comparisons confirmed the absence of alterations in the regulatory regions acrRA, soxRS, marORAB, acrSE and ramRA of selected mutants. Single bp and deduced Gly93→Val amino acid exchanges were present in fabI, the target gene of triclosan, starting from a concentration of 1 µg/ml TRC used for MPC determinations. The fabI genes were up to 12.4-fold up-regulated. Complementation experiments confirmed the contribution of Gly93→Val exchanges and fabI overexpression to decreased triclosan susceptibility. MIC values of mutants compared to parent strains were even equal or resulted in a more susceptible phenotype (1-2 dilution steps for the aminoglycoside antibiotics kanamycin and gentamicin as well as for the biocide chlorhexidine. Growth rates of selected mutants were significantly lower and hence, might partly explain the rare occurrence of Salmonella field isolates exhibiting

  5. Determination of aminoglycoside residues in milk and muscle based on a simple and fast extraction procedure followed by liquid chromatography coupled to tandem mass spectrometry and time of flight mass spectrometry.

    Science.gov (United States)

    Arsand, Juliana Bazzan; Jank, Louíse; Martins, Magda Targa; Hoff, Rodrigo Barcellos; Barreto, Fabiano; Pizzolato, Tânia Mara; Sirtori, Carla

    2016-07-01

    Antibiotics are widely used in veterinary medicine mainly for treatment and prevention of diseases. The aminoglycosides are one of the antibiotics classes that have been extensively employed in animal husbandry for the treatment of bacterial infections, but also as growth promotion. The European Union has issued strict Maximum Residue Levels (MRLs) for aminoglycosides in several animal origin products including bovine milk, bovine, swine and poultry muscle. This paper describes a fast and simple analytical method for the determination of ten aminoglycosides (spectinomycin, tobramycin, gentamicin, kanamycin, hygromycin, apramycin, streptomycin, dihydrostreptomycin, amikacin and neomycin) in bovine milk and bovine, swine and poultry muscle. For sample preparation, an extraction method was developed using trichloroacetic acid and clean up with low temperature precipitation and C18 bulk. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to carry out quantitative analysis and liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-QTOF-MS) was used to screening purposes. Both methods were validated according to the European Union Commission Directive 2002/657/EC. Good performance characteristics were obtained for recovery, precision, calibration curve, specificity, decision limits (CCα) and detection capabilities (CCβ) in all matrices evaluated. The detection limit (LOD) and quantification limit (LOQ) were ranging from 5 to 100ngg(-1) and 12.5 to 250ngg(-1), respectively. Good linearity (r)-above 0.99-was achieved in concentrations ranging from 0.0 to 2.0×MRL. Recoveries ranged from 36.8% to 98.0% and the coefficient of variation from 0.9 to 20.2%, noting that all curves have been made into their own matrices in order to minimize the matrix effects. The CCβ values obtained in qualitative method were between 25 and 250ngg(-1). The proposed method showed to be simple, easy, and adequate for high-throughput analysis of a large

  6. Whole Genome Sequencing Based Characterization of Extensively Drug-Resistant Mycobacterium tuberculosis Isolates from Pakistan

    KAUST Repository

    Ali, Asho; Hasan, Zahra; McNerney, Ruth; Mallard, Kim; Hill-Cawthorne, Grant A.; Coll, Francesc; Nair, Mridul; Pain, Arnab; Clark, Taane G.; Hasan, Rumina

    2015-01-01

    Improved molecular diagnostic methods for detection drug resistance in Mycobacterium tuberculosis (MTB) strains are required. Resistance to first- and second- line anti-tuberculous drugs has been associated with single nucleotide polymorphisms (SNPs) in particular genes. However, these SNPs can vary between MTB lineages therefore local data is required to describe different strain populations. We used whole genome sequencing (WGS) to characterize 37 extensively drug-resistant (XDR) MTB isolates from Pakistan and investigated 40 genes associated with drug resistance. Rifampicin resistance was attributable to SNPs in the rpoB hot-spot region. Isoniazid resistance was most commonly associated with the katG codon 315 (92%) mutation followed by inhA S94A (8%) however, one strain did not have SNPs in katG, inhA or oxyR-ahpC. All strains were pyrazimamide resistant but only 43% had pncA SNPs. Ethambutol resistant strains predominantly had embB codon 306 (62%) mutations, but additional SNPs at embB codons 406, 378 and 328 were also present. Fluoroquinolone resistance was associated with gyrA 91-94 codons in 81% of strains; four strains had only gyr B mutations, while others did not have SNPs in either gyrA or gyrB. Streptomycin resistant strains had mutations in ribosomal RNA genes; rpsL codon 43 (42%); rrs 500 region (16%), and gidB (34%) while six strains did not have mutations in any of these genes. Amikacin/kanamycin/capreomycin resistance was associated with SNPs in rrs at nt1401 (78%) and nt1484 (3%), except in seven (19%) strains. We estimate that if only the common hot-spot region targets of current commercial assays were used, the concordance between phenotypic and genotypic testing for these XDR strains would vary between rifampicin (100%), isoniazid (92%), flouroquinolones (81%), aminoglycoside (78%) and ethambutol (62%); while pncA sequencing would provide genotypic resistance in less than half the isolates. This work highlights the importance of expanded

  7. Whole Genome Sequencing Based Characterization of Extensively Drug-Resistant Mycobacterium tuberculosis Isolates from Pakistan

    KAUST Repository

    Ali, Asho

    2015-02-26

    Improved molecular diagnostic methods for detection drug resistance in Mycobacterium tuberculosis (MTB) strains are required. Resistance to first- and second- line anti-tuberculous drugs has been associated with single nucleotide polymorphisms (SNPs) in particular genes. However, these SNPs can vary between MTB lineages therefore local data is required to describe different strain populations. We used whole genome sequencing (WGS) to characterize 37 extensively drug-resistant (XDR) MTB isolates from Pakistan and investigated 40 genes associated with drug resistance. Rifampicin resistance was attributable to SNPs in the rpoB hot-spot region. Isoniazid resistance was most commonly associated with the katG codon 315 (92%) mutation followed by inhA S94A (8%) however, one strain did not have SNPs in katG, inhA or oxyR-ahpC. All strains were pyrazimamide resistant but only 43% had pncA SNPs. Ethambutol resistant strains predominantly had embB codon 306 (62%) mutations, but additional SNPs at embB codons 406, 378 and 328 were also present. Fluoroquinolone resistance was associated with gyrA 91-94 codons in 81% of strains; four strains had only gyr B mutations, while others did not have SNPs in either gyrA or gyrB. Streptomycin resistant strains had mutations in ribosomal RNA genes; rpsL codon 43 (42%); rrs 500 region (16%), and gidB (34%) while six strains did not have mutations in any of these genes. Amikacin/kanamycin/capreomycin resistance was associated with SNPs in rrs at nt1401 (78%) and nt1484 (3%), except in seven (19%) strains. We estimate that if only the common hot-spot region targets of current commercial assays were used, the concordance between phenotypic and genotypic testing for these XDR strains would vary between rifampicin (100%), isoniazid (92%), flouroquinolones (81%), aminoglycoside (78%) and ethambutol (62%); while pncA sequencing would provide genotypic resistance in less than half the isolates. This work highlights the importance of expanded

  8. Transcriptome profiling identifies genes/pathways associated with experimental resistance to paromomycin in Leishmania donovani

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    Aditya Verma

    2017-12-01

    Full Text Available Widespread resistance towards antimony and reports of relapses following miltefosine treatment has severely affected the management of visceral leishmaniasis (VL in the Indian subcontinent. Paromomycin (PMM, an aminoglycoside antibiotic, has been licensed for VL treatment in India in 2007. Although its use is still restricted in the field, unraveling the molecular mechanism of resistance towards PMM is the key to preserve the drug. In this study, PMM resistant lines were selected up to 100 μM of PMM in three distinct field isolates of Leishmania donovani at promastigote stage. The resistance induced at promastigote level was also evident in amastigotes which showed 6 fold decreases in PMM susceptibility. Comparative transcriptome profiling of PMM resistant (PMM-R and the corresponding PMM sensitive (PMM-S parasites revealed modulated expression of 500 genes (1.5 fold cut off in PMM-R parasites. Selected genes were validated for their modulated expression by quantitative real-time PCR. Functional classification and pathway analysis of modulated genes indicated probable adaptations in drug resistant lines which included a reduced oxidative phosphorylation; b increased glycosomal succinate fermentation and substrate level phosphorylation; c dependency on lipids and amino acids for energy generation; d reduced DNA synthesis and increased DNA damage repair and e decreased protein synthesis and degradation. Interestingly, PMM-R parasites showed a marked increase in PMM susceptibility in presence of verapamil and amlodipine, antagonists of Ca2+ channel that are also modulators of ABC transporters. Moreover, infection of macrophages by PMM-R parasites led to modulated nitric oxide (NO levels while reactive oxygen species (ROS level remained unaltered. The present study highlights the putative mechanisms of PMM resistance in Leishmania. Keywords: Leishmania donovani, Drug resistance, Paromomycin, Transcriptome, ABC transporters, Nitric oxide, Visceral

  9. Mounting resistance of uropathogens to antimicrobial agents: A retrospective study in patients with chronic bacterial prostatitis relapse

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    Konstantinos Stamatiou

    2017-07-01

    Full Text Available Purpose: Despite recent progress in the management of chronic bacterial prostatitis (CBP, many cases relapse. Increased drug resistance patterns of responsible bacteria have been proposed as the most probable causative factor. Driven by the limited number of previous studies addressing this topic, we aimed to study whether antibiotic resistance increases in patients with CBP when relapse occurs. A secondary aim of this study was to determine the resistance patterns of responsible bacteria from patients with CBP. Materials and Methods: The study material consisted of bacterial isolates from urine and/or prostatic secretions obtained from patients with CBP. Bacterial identification was performed by using the Vitek 2 Compact system and susceptibility testing was performed by disc diffusion and/or the Vitek 2 system. Interpretation of susceptibility results was based on Clinical and Laboratory Standards Institute guidelines. Results: A total of 253 samples from patients diagnosed with CBP for the first time (group A and 137 samples from relapsing patients with a history of CBP and previous antibiotic treatment (group B were analyzed. A significant reduction in bacterial resistance to the less used antibiotics (TMP-SMX, tetracyclines, aminoglycosides, penicillins, and macrolides was noted. An increase in resistance to quinolones of many bacteria that cause CBP was also noted with the increase in resistance of enterococcus strains being alarming. Conclusions: Comparison of the resistance profile of CBP-responsible bacteria between samples from first-time-diagnosed patients and samples from relapsing patients revealed notable differences that could be attributed to previous antibiotic treatment.

  10. UPLC-MS/MS analysis of antibiotics in pharmaceutical effluent in Tunisia: ecotoxicological impact and multi-resistant bacteria dissemination.

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    Tahrani, Leyla; Mehri, Ines; Reyns, Tim; Anthonissen, Roel; Verschaeve, Luc; Khalifa, Anis Bel Haj; Loco, Joris Van; Abdenaceur, Hassen; Mansour, Hedi Ben

    2018-05-01

    The UPLC MS/MS analysis showed the presence of the two antibiotics in the pharmaceutical industry discharges during 3 months; norfloxacin and spiramycin which were quantified with the mean concentrations of 226.7 and 84.2 ng mL -1 , respectively. Sixteen resistant isolates were obtained from the pharmaceutical effluent and identified by sequencing. These isolates belong to different genera, namely Citrobacter, Acinetobacter, Pseudomonas, Delftia, Shewanella, and Rheinheimera. The antibiotic resistance phenotypes of these isolates were determined (27 tested antibiotics-discs). All the studied isolates were found resistant to amoxicillin and gentamicin, and 83.33% of isolates were resistant to ciprofloxacin. Multiple antibiotic resistances were revealed against β-lactams, quinolones, and aminoglycosides families. Our overall results suggest that the obtained bacterial isolates may constitute potential candidates for bioremediation and can be useful for biotechnological applications. Genotoxic effects were assessed by a battery of biotests; the pharmaceutical wastewater was genotoxic according to the bacterial Vitotox test and micronuclei test. Genotoxicity was also evaluated by the comet test; the tail DNA damages reached 38 and 22% for concentrated sample (10×) and non-concentrated sample (1×), respectively. However, the histological sections of kidney and liver's mice treated by pharmaceutical effluent showed normal histology and no visible structural effects or alterations as cytolysis, edema, or ulcerative necrosis were observed. Residual antibiotics can reach water environment through wastewater and provoke dissemination of the antibiotics resistance and induce genotoxic effects.

  11. Antimicrobial resistance of Campylobacter jejuni and Campylobacter coli from poultry in Italy.

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    Giacomelli, Martina; Salata, Cristiano; Martini, Marco; Montesissa, Clara; Piccirillo, Alessandra

    2014-04-01

    This study was aimed at assessing the antimicrobial resistance (AMR) of Campylobacter isolates from broilers and turkeys reared in industrial farms in Northern Italy, given the public health concern represented by resistant campylobacters in food-producing animals and the paucity of data about this topic in our country. Thirty-six Campylobacter jejuni and 24 Campylobacter coli isolated from broilers and 68 C. jejuni and 32 C. coli from turkeys were tested by disk diffusion for their susceptibility to apramycin, gentamicin, streptomycin, cephalothin, cefotaxime, ceftiofur, cefuroxime, ampicillin, amoxicillin+clavulanic acid, nalidixic acid, flumequine, enrofloxacin, ciprofloxacin, erythromycin, tilmicosin, tylosin, tiamulin, clindamycin, tetracycline, sulfamethoxazole+trimethoprim, chloramphenicol. Depending on the drug, breakpoints provided by Comité de l'antibiogramme de la Société Française de Microbiologie, Clinical and Laboratory Standards Institute, and the manufacturer were followed. All broiler strains and 92% turkey strains were multidrug resistant. Very high resistance rates were detected for quinolones, tetracycline, and sulfamethoxazole+trimethoprim, ranging from 65% to 100% in broilers and from 74% to 96% in turkeys. Prevalence of resistance was observed also against ampicillin (97% in broilers, 88% in turkeys) and at least three cephalosporins (93-100% in broilers, 100% in turkeys). Conversely, no isolates showed resistance to chloramphenicol and tiamulin. Susceptibility prevailed for amoxicillin+clavulanic acid and aminoglycosides in both poultry species, and for macrolides and clindamycin among turkey strains and among C. jejuni from broilers, whereas most C. coli strains from broilers (87.5%) were resistant. Other differences between C. jejuni and C. coli were observed markedly in broiler isolates, with the overall predominance of resistance in C. coli compared to C. jejuni. This study provides updates and novel data on the AMR of broiler and

  12. Removal of selected PPCPs, EDCs, and antibiotic resistance genes in landfill leachate by a full-scale constructed wetlands system.

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    Yi, Xinzhu; Tran, Ngoc Han; Yin, Tingru; He, Yiliang; Gin, Karina Yew-Hoong

    2017-09-15

    Landfill leachate could be a significant source of emerging contaminants (ECs) and antibiotic resistance genes (ARGs) into the environment. This study provides the first information on the occurrence of selected ECs and ARGs in raw leachate from 16-year old closed landfill site in Singapore. Among the investigated ECs, acetaminophen (ACT), bisphenol A (BPA), clofibric acid (CA), caffeine (CF), crotamiton (CTMT), diclofenac (DCF), N,N-diethyl-m-toluamide (DEET), gemfibrozil (GFZ), lincomycin (LIN), salicylic acid (SA), and sulfamethazine (SMZ) were the most frequently detected compounds in raw landfill leachate. The concentrations of detected ECs in raw landfill leachate varied significantly, from below quantification limit to 473,977 ng/L, depending on the compound. In this study, Class I integron (intl1) gene and ten ARGs were detected in raw landfill leachate. Sulfonamide resistance (sul1, sul2, and dfrA), aminoglycoside resistance (aac6), tetracycline resistance (tetO), quinolone resistance (qnrA), and intl1 were ubiquitously present in raw landfill leachate. Other resistance genes, such as beta-lactam resistance (blaNMD1, blaKPC, and blaCTX) and macrolide-lincosamide resistance (ermB) were also detected, detection frequency of 90%) in the investigated hybrid CW system. This hybrid CW system was also found to be effective in the reduction of several ARGs (intl1, sul1, sul2, and qnrA). Aeration lagoons and reed beds appeared to be the most important treatment units of the hybrid CW for removing the majority of ECs from the leachate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Distribution of virulence determinants among antimicrobial-resistant and antimicrobial-susceptible Escherichia coli implicated in urinary tract infections.

    Science.gov (United States)

    Stephenson, Sam; Brown, P D

    2016-01-01

    Uropathogenic Escherichia coli (UPEC) rely on the correlation of virulence expression with antimicrobial resistance to persist and cause severe urinary tract infections (UTIs). We assessed the virulence pattern and prevalence among UPEC strains susceptible and resistant to multiple antimicrobial classes. A total of 174 non-duplicate UPEC strains from patients with clinically significant UTIs were analysed for susceptibility to aminoglycoside, antifolate, cephalosporin, nitrofuran and quinolone antibiotics for the production of extended-spectrum β-lactamases and for the presence of six virulence determinants encoding adhesins (afimbrial, Type 1 fimbriae, P and S-fimbriae) and toxins (cytotoxic necrotising factor and haemolysin). Relatively high resistance rates to nalidixic acid, ciprofloxacin, cephalothin and trimethoprim-sulfamethoxazole (82%, 78%, 62% and 59%, respectively) were observed. Fourteen distinct patterns were identified for the virulence determinants such as afaBC, cnfI, fimH, hylA, papEF and sfaDE. The toxin gene, cnfI (75.3%), was the second most prevalent marker to the adhesin, fimH (97.1%). The significant association of sfaDE/hylA (P < 0.01) among antimicrobial resistant and susceptible strains was also observed notwithstanding an overall greater occurrence of virulence factors among the latter. This study provides a snapshot of UPEC complexity in Jamaica and highlights the significant clonal heterogeneity among strains. Such outcomes emphasise the need for evidence-based strategies in the effective management and control of UTIs.

  14. Antimicrobial Resistance Characteristics and Phylogenetic Groups of Escherichia coli Isolated From Diarrheic Calves in Southeast of Iran

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    Zahedeh Naderi

    2016-11-01

    Full Text Available Background: Antimicrobial resistance is one of the main challenges in diarrheal diseases in human and animals. Regardless to the main reason of the disease, approximately all antimicrobial actions including treatment, control and prevention are mostly centralized against Escherichia coli (E. coli strains. Objectives: This work purposed to antimicrobial resistance (AR and determinate virulence genes and phylogenetic groups in E. coli isolates (n=170 obtained from calves with diarrhea. Materials and methods: Isolates were molecular characterized for 17 AR genes and 3 phylogenetic sequences. AR phenotyping were performed on all strains for 12 antimicrobial agents by using disc diffusion method. Results: All AR genes but qnrS were identified with different prevalence in E. coli isolates that the most common genes were aadA (20%, blaTEM (11.7% and sulII (11.2 % belonging to aminoglycoside, β-lactamase and sulphonamide families, respectively. Resistance to the penicillin and sulphamethoxazole drugs was found in 100% of isolates and followed by tetracycline (73.5%, streptomycin (60%, trimethoprim sulphamethoxazole (56.5% and kanamycin (53.5%. The phylogenetic groups A and B1 considerably surrounded the majority of isolates with the frequency of 65.8% and 30.6%, respectively. Conclusions: In Iran, diarrheic calves have an important role as reservoir of resistant E. coli strains against the some drugs which are registered for treatment of calf diarrhea.

  15. Polymorphism of antibiotic-inactivating enzyme driven by ecology expands the environmental resistome.

    Science.gov (United States)

    Kim, Dae-Wi; Thawng, Cung Nawl; Choi, Jung-Hye; Lee, Kihyun; Cha, Chang-Jun

    2018-01-01

    The environmental resistome has been recognized as the origin and reservoir of antibiotic resistance genes and considered to be dynamic and ever expanding. In this study, a targeted gene sequencing approach revealed that the polymorphic diversity of the aminoglycoside-inactivating enzyme AAC(6')-Ib was ecological niche-specific. AAC(6')-Ib-cr, previously known as a clinical variant, was prevalent in various soils and the intestines of chickens and humans, suggesting that this variant might not have arisen from adaptive mutations in the clinic but instead originated from the environment. Furthermore, ecologically dominant polymorphic variants of AAC(6')-Ib were characterized and found to display different substrate specificities for quinolones and aminoglycosides, conferring the altered resistance spectra. Interestingly, a novel variant with the D179Y substitution showed an extended resistance spectrum to the recently developed fluoroquinolone gemifloxacin. Our results suggest that soil and animal microbiomes could be major reservoirs of antibiotic resistance; polymorphic diversity expands the antibiotic resistome in the environment, resulting in the potential emergence of novel resistance.

  16. Genome Comparison of Erythromycin Resistant Campylobacter from Turkeys Identifies Hosts and Pathways for Horizontal Spread of erm(B Genes

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    Diego Florez-Cuadrado

    2017-11-01

    Full Text Available Pathogens in the genus Campylobacter are the most common cause of food-borne bacterial gastro-enteritis. Campylobacteriosis, caused principally by Campylobacter jejuni and Campylobacter coli, is transmitted to humans by food of animal origin, especially poultry. As for many pathogens, antimicrobial resistance in Campylobacter is increasing at an alarming rate. Erythromycin prescription is the treatment of choice for clinical cases requiring antimicrobial therapy but this is compromised by mobility of the erythromycin resistance gene erm(B between strains. Here, we evaluate resistance to six antimicrobials in 170 Campylobacter isolates (133 C. coli and 37 C. jejuni from turkeys. Erythromycin resistant isolates (n = 85; 81 C. coli and 4 C. jejuni were screened for the presence of the erm(B gene, that has not previously been identified in isolates from turkeys. The genomes of two positive C. coli isolates were sequenced and in both isolates the erm(B gene clustered with resistance determinants against aminoglycosides plus tetracycline, including aad9, aadE, aph(2″-IIIa, aph(3′-IIIa, and tet(O genes. Comparative genomic analysis identified identical erm(B sequences among Campylobacter from turkeys, Streptococcus suis from pigs and Enterococcus faecium and Clostridium difficile from humans. This is consistent with multiple horizontal transfer events among different bacterial species colonizing turkeys. This example highlights the potential for dissemination of antimicrobial resistance across bacterial species boundaries which may compromise their effectiveness in antimicrobial therapy.

  17. Detecting cryptic speciation in the widespread and morphologically conservative carpet chameleon (Furcifer lateralis) of Madagascar.

    Science.gov (United States)

    Florio, A M; Ingram, C M; Rakotondravony, H A; Louis, E E; Raxworthy, C J

    2012-07-01

    Species delimitation within recently evolved groups can be challenging because species may be difficult to distinguish morphologically. Following the General Lineage Concept, we apply a multiple evidence approach to assess species limits within the carpet chameleon Furcifer lateralis, which is endemic to Madagascar and exported in large numbers for the pet trade. Cryptic speciation within F. lateralis was considered likely because this species (1) has a vast distribution, (2) occupies exceptionally diverse habitats and (3) exhibits subtle regional differences in morphology. Phylogenetic trees reconstructed using nuclear and mitochondrial genes recovered three well-supported clades corresponding with geography. Morphological results based on canonical variates analysis show that these clades exhibit subtle differences in head casque morphology. Ecological niche modelling results found that these phylogenetic groups also occupy unique environmental space and exhibit patterns of regional endemism typical of other endemic reptiles. Combined, our findings provide diverse yet consistent evidence for the existence of three species. Consequently, we elevate the subspecies F. lateralis major to species rank and name a new species distributed in northern and western Madagascar. Initial ecological divergence, associated with speciation of F. lateralis in humid eastern habitat, fits the Ecographic Constraint model for species diversification in Madagascar. By contrast, the second speciation event provides some support for the Riverine Barrier model, with the Mangoky River possibly causing initial isolation between species. These findings thus support two contrasting models of speciation within closely related species and demonstrate the utility of applying a combined-evidence approach for detecting cryptic speciation. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For E