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Sample records for aminoglycosides

  1. Glomerular nephrotoxicity of aminoglycosides

    International Nuclear Information System (INIS)

    Martinez-Salgado, Carlos; Lopez-Hernandez, Francisco J.; Lopez-Novoa, Jose M.

    2007-01-01

    Aminoglycoside antibiotics are the most commonly used antibiotics worldwide in the treatment of Gram-negative bacterial infections. However, aminoglycosides induce nephrotoxicity in 10-20% of therapeutic courses. Aminoglycoside-induced nephrotoxicity is characterized by slow rises in serum creatinine, tubular necrosis and marked decreases in glomerular filtration rate and in the ultrafiltration coefficient. Regulation of the ultrafiltration coefficient depends on the activity of intraglomerular mesangial cells. The mechanisms responsible for tubular nephrotoxicity of aminoglycosides have been intensively reviewed previously, but glomerular toxicity has received less attention. The purpose of this review is to critically assess the published literature regarding the toxic mechanisms of action of aminoglycosides on renal glomeruli and mesangial cells. The main goal of this review is to provide an actualized and mechanistic vision of pathways involved in glomerular toxic effects of aminoglycosides

  2. Aminoglycoside induced ototoxicity associated with mitochondrial ...

    African Journals Online (AJOL)

    . Joseph Foster II, Mustafa Tekin. Abstract. Despite the risk of permanent ototoxic effects, aminoglycosides remain commonly utilized antibiotics worldwide due to low cost and efficiency in treating severe infections. Over the last two decades, ...

  3. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

  4. Analysis of Aminoglycoside Modifying Enzyme Genes Responsible for High-Level Aminoglycoside Resistance among Enterococcal Isolates

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    Vishal Shete

    2017-01-01

    Full Text Available Enzymatic modification results in high-level resistance to aminoglycoside (HLAR, which eliminates the synergistic bactericidal effect of combined exposure to a cell wall-active agent and an aminoglycoside. So aim of the study was to determine prevalence of HLAR enterococcal isolate and to study distribution of aminoglycoside modifying enzyme genes in them. A total of 100 nonrepeat isolates of enterococci from various clinical samples were analyzed. As per Clinical and Laboratory Standards Institute guidelines enterococci were screened for HLAR by Kirby-Bauer disc diffusion method. Minimum inhibitory concentration of all isolates for gentamicin and streptomycin was determined by E-test. Multiplex polymerase chain reaction (PCR was carried out for HLAR enterococcal isolates to identify aminoglycoside modifying enzymes genes responsible for resistance. 60% isolates were found to be high-level gentamicin resistant (HLGR whereas 45% isolates were found to be high-level streptomycin resistant (HLSR. By multiplex PCR 80% HLGR isolates carried bifunctional aminoglycoside modifying enzyme gene aac(6′-Ie-aph(2′′-Ia whereas 18 out of 45 high-level streptomycin resistant, that is, 40%, isolates carried aph(3′-IIIa. However, aph(2′′-Ib, aph(2′′-Ic, aph(2′′-Id, and ant(4′-Ia genes which encode other aminoglycosides modifying enzymes were not detected. Bifunctional aminoglycoside modifying enzyme gene aac(6′-Ie-aph(2′′-Ia is the predominant gene responsible for HLAR.

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

    Science.gov (United States)

    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.

  6. DNA-Aptamers Binding Aminoglycoside Antibiotics

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    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.

  7. Aminoglycoside resistance profile and structural architecture of the aminoglycoside acetyltransferase AAC(6')-Im.

    Science.gov (United States)

    Smith, Clyde A; Bhattacharya, Monolekha; Toth, Marta; Stewart, Nichole K; Vakulenko, Sergei B

    2017-11-09

    Aminoglycoside 6'-acetyltransferase-Im (AAC(6')-Im) is the closest monofunctional homolog of the AAC(6')-Ie acetyltransferase of the bifunctional enzyme AAC(6')-Ie/APH(2")-Ia. The AAC(6')-Im acetyltransferase confers 4- to 64-fold higher MICs to 4,6-disubstituted aminoglycosides and the 4,5-disubstituted aminoglycoside neomycin than AAC(6')-Ie, yet unlike AAC(6')-Ie, the AAC(6')-Im enzyme does not confer resistance to the atypical aminoglycoside fortimicin. The structure of the kanamycin A complex of AAC(6')-Im shows that the substrate binds in a shallow positively-charged pocket, with the N6' amino group positioned appropriately for an efficient nucleophilic attack on an acetyl-CoA cofactor. The AAC(6')-Ie enzyme binds kanamycin A in a sufficiently different manner to position the N6' group less efficiently, thereby reducing the activity of this enzyme towards the 4,6-disubstituted aminoglycosides. Conversely, docking studies with fortimicin in both acetyltransferases suggest that the atypical aminoglycoside might bind less productively in AAC(6')-Im, thus explaining the lack of resistance to this molecule.

  8. Synergistic ototoxicity due to noise exposure and aminoglycoside antibiotics.

    Science.gov (United States)

    Li, Hongzhe; Steyger, Peter S

    2009-01-01

    Acoustic exposure to high intensity and/or prolonged noise causes temporary or permanent threshold shifts in auditory perception, reflected by reversible or irreversible damage in the cochlea. Aminoglycoside antibiotics, used for treating or preventing life-threatening bacterial infections, also induce cytotoxicity in the cochlea. Combined noise and aminoglycoside exposure, particularly in neonatal intensive care units, can lead to auditory threshold shifts greater than simple summation of the two insults. The synergistic toxicity of acoustic exposure and aminoglycoside antibiotics is not limited to simultaneous exposures. Prior acoustic insult which does not result in permanent threshold shifts potentiates aminoglycoside ototoxicity. In addition, exposure to subdamaging doses of aminoglycosides aggravates noise-induced cochlear damage. The mechanisms by which aminoglycosides cause auditory dysfunction are still being unraveled, but likely include the following: 1) penetration into the endolymphatic fluid of the scala media, 2) permeation of nonselective cation channels on the apical surface of hair cells, and 3) generation of toxic reactive oxygen species and interference with other cellular pathways. Here we discuss the effect of combined noise and aminoglycoside exposure to identify pivotal synergistic events that can potentiate ototoxicity, in addition to a current understanding of aminoglycoside trafficking within the cochlea. Preventing the ototoxic synergy of noise and aminoglycosides is best achieved by using non-ototoxic bactericidal drugs, and by attenuating perceived noise intensity when life-saving aminoglycoside therapy is required.

  9. Aminoglycoside antibiotics and autism: a speculative hypothesis

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    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.

  10. Revisiting the Nucleotide and Aminoglycoside Substrate Specificity of the Bifunctional Aminoglycoside Acetyltransferase(6′)-Ie/Aminoglycoside Phosphotransferase(2″)-Ia Enzyme*

    Science.gov (United States)

    Frase, Hilary; Toth, Marta; Vakulenko, Sergei B.

    2012-01-01

    The bifunctional aminoglycoside-modifying enzyme aminoglycoside acetyltransferase(6′)-Ie/aminoglycoside phosphotransferase(2″)-Ia, or AAC(6′)-Ie/APH(2″)-Ia, is the major source of aminoglycoside resistance in Gram-positive bacterial pathogens. In previous studies, using ATP as the cosubstrate, it was reported that the APH(2″)-Ia domain of this enzyme is unique among aminoglycoside phosphotransferases, having the ability to inactivate an unusually broad spectrum of aminoglycosides, including 4,6- and 4,5-disubstituted and atypical. We recently demonstrated that GTP, and not ATP, is the preferred cosubstrate of this enzyme. We now show, using competition assays between ATP and GTP, that GTP is the exclusive phosphate donor at intracellular nucleotide levels. In light of these findings, we reevaluated the substrate profile of the phosphotransferase domain of this clinically important enzyme. Steady-state kinetic characterization using the phosphate donor GTP demonstrates that AAC(6′)-Ie/APH(2″)-Ia phosphorylates 4,6-disubstituted aminoglycosides with high efficiency (kcat/Km = 105-107 m−1 s−1). Despite this proficiency, no resistance is conferred to some of these antibiotics by the enzyme in vivo. We now show that phosphorylation of 4,5-disubstituted and atypical aminoglycosides are negligible and thus these antibiotics are not substrates. Instead, these aminoglycosides tend to stimulate an intrinsic GTPase activity of the enzyme. Taken together, our data show that the bifunctional enzyme efficiently phosphorylates only 4,6-disubstituted antibiotics; however, phosphorylation does not necessarily result in bacterial resistance. Hence, the APH(2″)-Ia domain of the bifunctional AAC(6′)-Ie/APH(2″)-Ia enzyme is a bona fide GTP-dependent kinase with a narrow substrate profile, including only 4,6-disubstituted aminoglycosides. PMID:23115238

  11. Overcoming Aminoglycoside Enzymatic Resistance: Design of Novel Antibiotics and Inhibitors

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    Sandra G. Zárate

    2018-01-01

    Full Text Available Resistance to aminoglycoside antibiotics has had a profound impact on clinical practice. Despite their powerful bactericidal activity, aminoglycosides were one of the first groups of antibiotics to meet the challenge of resistance. The most prevalent source of clinically relevant resistance against these therapeutics is conferred by the enzymatic modification of the antibiotic. Therefore, a deeper knowledge of the aminoglycoside-modifying enzymes and their interactions with the antibiotics and solvent is of paramount importance in order to facilitate the design of more effective and potent inhibitors and/or novel semisynthetic aminoglycosides that are not susceptible to modifying enzymes.

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

    Science.gov (United States)

    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.

  13. Occurrence of aminoglycoside-modifying enzymes genes (aac(6 ...

    African Journals Online (AJOL)

    Abstract. Background: Enzymatic modification of aminoglycosides is the primary mechanism of resistance by Pseudomonas aerug- inosa. Obejectives: We investigated the occurrence and mechanism of aminoglycosides resistance in P. aeruginosa isolates from hospitals in SouthWest Nigeria. Methods: A total of 54 ...

  14. MexY-promoted aminoglycoside resistance in Pseudomonas aeruginosa: involvement of a putative proximal binding pocket in aminoglycoside recognition.

    Science.gov (United States)

    Lau, Calvin Ho-Fung; Hughes, Daniel; Poole, Keith

    2014-04-22

    The resistance-nodulation-division (RND) family multidrug efflux system MexXY-OprM is a major determinant of aminoglycoside resistance in Pseudomonas aeruginosa, although the details of aminoglycoside recognition and export by MexY, the substrate-binding RND component of this efflux system, have not been elucidated. To identify regions/residues of MexY important for aminoglycoside resistance, plasmid-borne mexY was mutagenized and mutations that impaired MexY-promoted aminoglycoside (streptomycin) resistance were identified in a ΔmexY strain of P. aeruginosa. Sixty-one streptomycin-sensitive mexY mutants were recovered; among these, 7 unique mutations that yielded wild-type levels of MexY expression were identified. These mutations compromised resistance to additional aminoglycosides and to other antimicrobials and occurred in both the transmembrane and periplasmic regions of the protein. Mapping of the mutated residues onto a 3-dimensional structure of MexY modeled on Escherichia coli AcrB revealed that these tended to occur in regions implicated in general pump operation (transmembrane domain) and MexY trimer assembly (docking domain) and, thus, did not provide insights into aminoglycoside recognition. A region corresponding to a proximal binding pocket connected to a periplasm-linked cleft, part of a drug export pathway of AcrB, was identified in MexY and proposed to play a role in aminoglycoside recognition. To test this, selected residues (K79, D133, and Y613) within this pocket were mutagenized and the impact on aminoglycoside resistance was assessed. Mutations of D133 and Y613 compromised aminoglycoside resistance, while, surprisingly, the K79 mutation enhanced aminoglycoside resistance, confirming a role for this putative proximal binding pocket in aminoglycoside recognition and export. IMPORTANCE Bacterial RND pumps do not typically accommodate highly hydrophilic agents such as aminoglycosides, and it is unclear how those, such as MexY, which accommodate

  15. Protective effect of rasagiline in aminoglycoside ototoxicity.

    Science.gov (United States)

    Polony, G; Humli, V; Andó, R; Aller, M; Horváth, T; Harnos, A; Tamás, L; Vizi, E S; Zelles, T

    2014-04-18

    Sensorineural hearing losses (SNHLs; e.g., ototoxicant- and noise-induced hearing loss or presbycusis) are among the most frequent sensory deficits, but they lack effective drug therapies. The majority of recent therapeutic approaches focused on the trials of antioxidants and reactive oxygen species (ROS) scavengers in SNHLs. The rationale for these studies was the prominent role of disturbed redox homeostasis and the consequent ROS elevation. Although the antioxidant therapies in several animal studies seemed to be promising, clinical trials have failed to fulfill expectations. We investigated the potential of rasagiline, an FDA-approved monomanine oxidase type B inhibitor (MAO-B) inhibitor type anti-parkinsonian drug, as an otoprotectant. We showed a dose-dependent alleviation of the kanamycin-induced threshold shifts measured by auditory brainstem response (ABR) in an ototoxicant aminoglycoside antibiotic-based hearing loss model in mice. This effect proved to be statistically significant at a 6-mg/kg (s.c.) dose. The most prominent effect appeared at 16kHz, which is the hearing sensitivity optimum for mice. The neuroprotective, antiapoptotic and antioxidant effects of rasagiline in animal models, all targeting a specific mechanism of aminoglycoside injury, may explain this otoprotection. The dopaminergic neurotransmission enhancer effect of rasagiline might also contribute to the protection. Dopamine (DA), released from lateral olivocochlear (LOC) fibers, was shown to exert a protective action against excitotoxicity, a pathological factor in the aminoglycoside-induced SNHL. We have shown that rasagiline enhanced the electric stimulation-evoked release of DA from an acute mouse cochlea preparation in a dose-dependent manner. Using inhibitors of voltage-gated Na(+)-, Ca(2+) channels and DA transporters, we revealed that rasagiline potentiated the action potential-evoked release of DA by inhibiting the reuptake. The complex, multifactorial pathomechanism of SNHLs

  16. Preventing Ototoxic Synergy of Prior Noise Trauma During Aminoglycoside Therapy

    Science.gov (United States)

    2015-12-01

    Johns Hopkins University. 212 p (2007). 9. Liao S, et al. Noise Exposure in the Neonatal Intensive Care Unit : A Prospective Study. American Academy...AD_________________ Award Number: W81XWH-14-1-0006 TITLE: Preventing Ototoxic Synergy Of Prior Noise Trauma During Aminoglycoside Therapy ...Dec 2014 - 30 Nov 2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Preventing Ototoxic Synergy Of Prior Noise Trauma During Aminoglycoside Therapy

  17. 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.

  18. Aminoglycoside interactions and impacts on the eukaryotic ribosome

    Science.gov (United States)

    Prokhorova, Irina; Altman, Roger B.; Djumagulov, Muminjon; Shrestha, Jaya P.; Urzhumtsev, Alexandre; Ferguson, Angelica; Chang, Cheng-Wei Tom; Yusupov, Marat; Blanchard, Scott C.; Yusupova, Gulnara

    2017-01-01

    Aminoglycosides are chemically diverse, broad-spectrum antibiotics that target functional centers within the bacterial ribosome to impact all four principle stages (initiation, elongation, termination, and recycling) of the translation mechanism. The propensity of aminoglycosides to induce miscoding errors that suppress the termination of protein synthesis supports their potential as therapeutic interventions in human diseases associated with premature termination codons (PTCs). However, the sites of interaction of aminoglycosides with the eukaryotic ribosome and their modes of action in eukaryotic translation remain largely unexplored. Here, we use the combination of X-ray crystallography and single-molecule FRET analysis to reveal the interactions of distinct classes of aminoglycosides with the 80S eukaryotic ribosome. Crystal structures of the 80S ribosome in complex with paromomycin, geneticin (G418), gentamicin, and TC007, solved at 3.3- to 3.7-Å resolution, reveal multiple aminoglycoside-binding sites within the large and small subunits, wherein the 6′-hydroxyl substituent in ring I serves as a key determinant of binding to the canonical eukaryotic ribosomal decoding center. Multivalent binding interactions with the human ribosome are also evidenced through their capacity to affect large-scale conformational dynamics within the pretranslocation complex that contribute to multiple aspects of the translation mechanism. The distinct impacts of the aminoglycosides examined suggest that their chemical composition and distinct modes of interaction with the ribosome influence PTC read-through efficiency. These findings provide structural and functional insights into aminoglycoside-induced impacts on the eukaryotic ribosome and implicate pleiotropic mechanisms of action beyond decoding. PMID:29208708

  19. Genetic basis of enzymatic resistance of E. coli to aminoglycosides.

    Science.gov (United States)

    Ojdana, Dominika; Sieńko, Anna; Sacha, Paweł; Majewski, Piotr; Wieczorek, Piotr; Wieczorek, Anna; Tryniszewska, Elżbieta

    2017-07-29

    Over the past years, an increase in resistance to aminoglycosides has been observed among Enterobacteriaceae rods. This resistance development reduces therapeutic options for infections caused by multidrug-resistance organisms. Because of the changing epidemiology of extended-spectrum β-lactamases (ESBLs) and resistance to aminoglycosides, we investigated the prevalence of the aac(3)-Ia, aac(6')-Ib, ant(4')-IIa, ant(2")-Ia, and aph(3")-Ib genes encoding aminoglycoside-modifying enzymes (AMEs) in ESBL-producing Escherichia coli as well as ESBL-non-producing isolates. To understand bacterial resistance to aminoglycoside antibiotics, we estimated resistance phenotypes and the presence of genes responsible for this resistance. The study was conducted on 44 E.coli strains originated from patients hospitalized at University Hospital of Bialystok. MIC values were obtained for gentamicin, amikacin, netilmicin, and tobramycin. Isolates were tested for the presence of the aac(3)-Ia, aac(6')-Ib, ant(4')-IIa, ant(2")-Ia, and aph(3")-Ib genes with the use of the PCR technique. Resistance to aminoglycosides was found in 79.5% of the isolates. The highest percentages of resistance were observed for tobramycin (70,5%) and gentamicin (59%), followed by netilmicin (43.2%) and amikacin (11.4%). PCR assays revealed the presence of aac(6')-Ib among 26 (59.2%) strains, aph(3")-Ib among 16 (36.2%), aac(3)-Ia among 7 (15.9%), and ant(2")-Ia among 2 (4.6%) strains. The enzymatic resistance against aminoglycosides in northeastern Poland among clinical isolates of E. coli is predominantly caused by aac(6')-Ib and aph(3")-Ib. Amikacin may be used for therapy of infections caused by ESBL-producing E. coli, because of the low rates of resistance. Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.

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

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    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 ...

  1. 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

  2. Thermodynamics of aminoglycoside and acyl-coenzyme A binding to the Salmonella enterica AAC(6')-Iy aminoglycoside N-acetyltransferase.

    Science.gov (United States)

    Hegde, Subray S; Dam, Tarun K; Brewer, C Fred; Blanchard, John S

    2002-06-11

    Kinetic and mechanistic studies on the chromosomally encoded aminoglycoside 6'-N-acetyltransferase, AAC(6')-Iy, of Salmonella enterica that confers resistance toward aminoglycosides have been previously reported [Magnet et al. (2001) Biochemistry 40, 3700-3709]. In the present study, equilibrium binding and the thermodynamic parameters of binding of aminoglycosides and acyl-coenzyme A derivatives to AAC(6')-Iy and of two mutants, C109A and the C109A/C70A double mutant, have been studied using fluorescence spectroscopy and isothermal titration calorimetry (ITC). Association constants for different aminoglycosides varied greatly (4 x 10(4)-150 x 10(4)) while the association constants of several acyl-coenzyme A derivatives were similar (3.2 x 10(4)-4.5 x 10(4)). The association constants and van't Hoff enthalpy changes derived from intrinsic protein fluorescence changes were in agreement with independently measured values from isothermal titration calorimetry studies. Binding of both aminoglycosides and acyl-coenzyme A derivatives is strongly enthalpically driven and revealed opposing negative entropy changes, resulting in enthalpy-entropy compensation. The acetyltransferase exhibited a temperature-dependent binding of tobramycin with a negative heat capacity value of 410 cal mol(-1) K(-1). Isothermal titration studies of acetyl-coenzyme A and tobramycin binding to mutant forms of the enzyme indicated that completely conserved C109 does not play any direct role in the binding of either of the substrates, while C70 is directly involved in aminoglycoside binding. These results are discussed and compared with previous steady-state kinetic studies of the enzyme.

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

    Science.gov (United States)

    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.

  4. Appropriateness of aminoglycoside prescriptions in a French university hospital.

    Science.gov (United States)

    Muller, A; Leroy, J; Patry, I; Hénon, T; Hocquet, D; Chirouze, C; Bertrand, X

    2016-09-01

    Aminoglycosides are a major class of antibiotics. Their use is particularly interesting in the treatment of severe infections but their toxicity is well known. They are mostly prescribed combined with other agents and as first-line treatments. We aimed to assess the appropriateness of aminoglycoside prescriptions in a French university hospital on the basis of the latest French recommendations published in 2011. We conducted a prospective study between January 17th and February 4th, 2014 to assess prescription modalities of aminoglycosides on the basis of the following criteria: indication, duration of treatment, dosing schedule, administration modalities, and drug level monitoring. Prescriptions were then compared to the 2011 national guidelines. A total of 68 consecutive prescriptions were analyzed and only 47.8% complied with guidelines. Most physicians complied with recommendations, particularly with the indication for severe infections (95.6%), the administration of a single daily dose (92.6%), and the slow intravenous infusion (30minutes) administration (84%). However, physicians tended to prescribe lower doses than recommended (40.3%), especially to patients presenting with renal insufficiency, and drug level monitoring was not optimal. Although new and accurate national recommendations were recently published, aminoglycoside prescription is still not optimal, in particular for dosing and plasma concentration monitoring. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  5. In vitro effect of aminoglycosides and fluoroquinolones on ...

    African Journals Online (AJOL)

    A viable isolate of coagulase positive and pigment forming Staphylococcus aureus obtained from conjunctival swabs used in the study was treated with aminoglycosides (gentamicin, 0.3%, and tobramycin bramycin, 0.3%, ophthalmic solution) and fluoroquinolones (gatifloxacin 0.3% and moxifloxacin, 0.3% ophthalmic ...

  6. 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 ...

  7. High Level Aminoglycoside Resistance and Distribution of Aminoglycoside Resistant Genes among Clinical Isolates of Enterococcus Species in Chennai, India

    Directory of Open Access Journals (Sweden)

    Elango Padmasini

    2014-01-01

    Full Text Available Enterococci are nosocomial pathogen with multiple-drug resistance by intrinsic and extrinsic mechanisms. Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. 178 enterococcal isolates were analyzed in this study. E. faecalis is identified to be the predominant Enterococcus species, along with E. faecium, E. avium, E. hirae, E. durans, E. dispar and E. gallinarum. High level aminoglycoside resistance (HLAR by MIC for gentamicin (GM, streptomycin (SM and both (GM + SM antibiotics was found to be 42.7%, 29.8%, and 21.9%, respectively. Detection of aminoglycoside modifying enzyme encoding genes (AME in enterococci was identified by multiplex PCR for aac(6′-Ie-aph(2′′-Ia; aph(2′′-Ib; aph(2′′-Ic; aph(2′′-Id and aph(3′-IIIa genes. 38.2% isolates carried aac(6′-Ie-aph(2′′-Ia gene and 40.4% isolates carried aph(3′-IIIa gene. aph(2′′-Ib; aph(2′′-Ic; aph(2′′-Id were not detected among our study isolates. aac(6′-Ie-aph(2′′-Ia and aph(3′-IIIa genes were also observed in HLAR E. durans, E. avium, E. hirae, and E. gallinarum isolates. This indicates that high level aminoglycoside resistance genes are widely disseminated among isolates of enterococci from Chennai.

  8. 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 ...

  9. Multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides.

    Science.gov (United States)

    Chen, Mingsheng; Hu, Mei; Wang, Dali; Wang, Guojian; Zhu, Xinyuan; Yan, Deyue; Sun, Jian

    2012-06-20

    Multifunctional gene vectors with high transfection, low cytotoxicity, and good antitumor and antibacterial activities were prepared from natural aminoglycosides. Through the Michael-addition polymerization of gentamycin and N,N'-methylenebisacrylamide, cationic hyperbranched glycoconjugated polymers were synthesized, and their physical and chemical properties were analyzed by FTIR, (1)H NMR, (13)C NMR, GPC, ζ-potential, and acid-base titration techniques. The cytotoxicity of these hyperbranched glycoconjugated polycations was low because of the hydrolysis of degradable glycosidic and amide linkages in acid conditions. Owing to the presence of various primary, secondary, and tertiary amines in the polymers, hyperbranched glycoconjugated polymers showed high buffering capacity and strong DNA condensation ability, resulting in the high transfection efficiency. In the meantime, due to the introduction of natural aminoglycosides into the polymeric backbone, the resultant hyperbranched glycoconjugated polymers inhibited the growth of cancer cells and bacteria efficiently. Combining the gene transfection, antitumor, and antibacterial abilities together, the multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides may play an important role in protecting cancer patients from bacterial infections.

  10. 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.

  11. Hearing loss and nephrotoxicity treatment in patients with in long-term aminoglycoside tuberculosis

    NARCIS (Netherlands)

    van Altena, R

    OBJECTIVE: To investigate the ototoxic and nephrotoxic effects of long-term use of aminoglycosides. DESIGN: Patients treated for tuberculosis with aminoglycosides were evaluated for hearing loss and nephrotoxicity for a minimum of 14 days. RESULTS: Hearing loss of 15 decibels (dB) at two or more

  12. Identification of aminotransferase genes for biosynthesis of aminoglycoside antibiotics from soil DNA.

    Science.gov (United States)

    Nagaya, Atsushi; Takeyama, Satoko; Tamegai, Hideyuki

    2005-07-01

    Aminoglycoside has been known as a clinically important antibiotic for a long time, but genetic information for the biosynthesis of aminoglycoside is still insufficient. In this study, we tried to clone aminoglycoside-biosynthetic genes from soil DNA for accumulation of genetic information. We chose the genes encoding L-glutamine:(2-deoxy-)scyllo-inosose aminotransferase as the target, because it is specific for all types of aminoglycoside biosynthesis. By degenerate PCR, we obtained 33 individual clones that were homologous with aminotransferase genes in aminoglycoside biosynthesis. Phylogenetic analysis and alignment of these genes showed that horizontal gene transfer has occurred in the soil. Among these, several quite interesting genes were obtained. Some genes probably originated from non-actinomycetes, and some were far from the known homologs. These genes can be useful markers for the isolation of entire gene clusters and originating organisms.

  13. 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.

  14. [Investigation of molecular mechanisms of aminoglycoside resistance in Salmonella].

    Science.gov (United States)

    Zubritskiĭ, A V; Il'ina, E N; Strel'chenko, S A; Malakhova, M V; Lenev, S V; Skliarov, O D; Panin, A N; Govorun, V M

    2011-01-01

    The spread of aminoglycoside resistance phenotype and respective genetic resistance determinants was evaluated in 243 Salmonella strains isolated within 1948-2010 and stored in the Culture Collection of the Russian State Research Institute for Control, Standardization and Certification of Veterinary Preparations (Moscow). The Salmonella strains showed resistance to streptomycin and gentamicin in 3.7% (n = 9) and 0.8% (n = 2) of the isolates respectively. Intermediate resistance to streptomycin was recorded in 9.9% (n = 24) of the isolates. To detect the genes responsible for the aminoglycoside resistance, primers for aadA1, aadA2, aadB, aphA1, aphA3, sat, strA, strB, aphA, aacC, rmtB, armA and rpsL genes amplification and sequencing were designed. The strains with lower susceptibility to streptomycin harbored aadA1, aadA2, strA, strB resistance genes encoding enzymes for aminoglicoside modification and rpsL mutant allele (K42N, G91D). Genetic mechanisms able to explain the gentamicin resistance development were not detected. Some strains carried genetic markers of streptomycine resistance but had no clinically sufficient resistance to it. In this regard, genetic testing is essential for prevention of drug resistance spreading due to horizontal transfer of genes in microbial population.

  15. The Impact of Aminoglycosides on the Dynamics of Translation Elongation

    Directory of Open Access Journals (Sweden)

    Albert Tsai

    2013-02-01

    Full Text Available Inferring antibiotic mechanisms on translation through static structures has been challenging, as biological systems are highly dynamic. Dynamic single-molecule methods are also limited to few simultaneously measurable parameters. We have circumvented these limitations with a multifaceted approach to investigate three structurally distinct aminoglycosides that bind to the aminoacyl-transfer RNA site (A site in the prokaryotic 30S ribosomal subunit: apramycin, paromomycin, and gentamicin. Using several single-molecule fluorescence measurements combined with structural and biochemical techniques, we observed distinct changes to translational dynamics for each aminoglycoside. While all three drugs effectively inhibit translation elongation, their actions are structurally and mechanistically distinct. Apramycin does not displace A1492 and A1493 at the decoding center, as demonstrated by a solution nuclear magnetic resonance structure, causing only limited miscoding; instead, it primarily blocks translocation. Paromomycin and gentamicin, which displace A1492 and A1493, cause significant miscoding, block intersubunit rotation, and inhibit translocation. Our results show the power of combined dynamics, structural, and biochemical approaches to elucidate the complex mechanisms underlying translation and its inhibition.

  16. The impact of aminoglycosides on the dynamics of translation elongation

    Science.gov (United States)

    Tsai, Albert; Uemura, Sotaro; Johansson, Magnus; Puglisi, Elisabetta Viani; Marshall, R. Andrew; Aitken, Colin Echeverría; Korlach, Jonas; Ehrenberg, Måns; Puglisi, Joseph D.

    2013-01-01

    Inferring antibiotic mechanisms on translation through static structures has been challenging as biological systems are highly dynamic. Dynamic single-molecule methods are also limited to few simultaneously-measurable parameters. We have circumvented these limitations with a multifaceted approach to investigate three structurally-distinct aminoglycosides that bind to the aminoacyl-tRNA site (A site) in the prokaryotic 30S ribosomal subunit: apramycin, paromomycin, and gentamicin. Using several single-molecule fluorescence measurements combined with structural and biochemical techniques, we observed distinct changes to translational dynamics for each aminoglycoside. While all three drugs effectively inhibit translation elongation, their actions are structurally and mechanistically distinct. Apramycin does not displace A1492 and A1493 at the decoding center, as demonstrated by a solution NMR structure, causing only limited miscoding; instead it primarily blocks translocation. Paromomycin and gentamicin, which displace A1492 and A1493, cause significant miscoding, block intersubunit rotation, and inhibit translocation. Our results show the power of combined dynamics, structural, and biochemical approaches to elucidate the complex mechanisms underlying translation and its inhibition. PMID:23416053

  17. 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.

  18. Cloning, overexpression, and purification of aminoglycoside antibiotic nucleotidyltransferase (2'')-Ia: conformational studies with bound substrates.

    Science.gov (United States)

    Ekman, D R; DiGiammarino, E L; Wright, E; Witter, E D; Serpersu, E H

    2001-06-19

    Aminoglycoside nucleotidyltransferase (2'')-Ia [ANT (2'')-Ia] was cloned from Pseudomonas aeruginosa and purified from overexpressing Escherichia coli BL21(DE3) cells. The first enzyme-bound conformation of an aminoglycoside antibiotic in the active site of an aminoglycoside nucleotidyltransferase was determined using the purified aminoglycoside nucleotidyltransferase (2' ')-Ia. The conformation of the aminoglycoside antibiotic isepamicin, a psuedo-trisaccharide, bound to aminoglycoside nucleotidyltransferase (2' ')-Ia has been determined using NMR spectroscopy. Molecular modeling, employing experimentally determined interproton distances, resulted in two different enzyme-bound conformations (conformer 1 and conformer 2) of isepamicin. Conformer 1 was by far the major conformer defined by the following average glycosidic dihedral angles: PhiBC = -65.26 +/- 1.63 degrees and PsiBC = -54.76 +/- 4.64 degrees. Conformer 1 was further subdivided into one major (conformer 1a) and two minor components (conformers 1b and 1c) based on the comparison of glycosidic dihedral angles PhiAB and PsiAB. The arrangement of substrates in the enzyme.metal-ATP.isepamicin complex was determined on the basis of the measured effect of the paramagnetic substrate analogue Cr(H2O)4ATP on the relaxation rates of substrate protons which were used to determine relative distances of isepamicin protons to the Cr3+. Both conformers of isepamicin yielded arrangements that satisfied the NOE restraints and the observed paramagnetic effects of Cr(H2O)4ATP. It has been suggested that aminoglycosides use both electrostatic interactions and hydrogen bonds in binding to RNA and that the contacts made by the A and B rings to RNA are the most important for binding [Fourmy, D., Recht, M. I., Blanchard, S. C., and Puglisi, J. D. (1996) Science 274, 1367-1371]. Comparisons based on the determined conformations of enzyme-bound aminoglycoside antibiotics also suggested that interactions of rings A and B with

  19. 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.

  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. Enzymatic method for inactivation of aminoglycosides during measurement of postantibiotic effect

    NARCIS (Netherlands)

    J.G. den Hollander (Jan); J.W. Mouton (Johan); I.A.J.M. Bakker-Woudenberg (Irma); F.P. Vleggaar (Frank); M.P.J. van Goor (Marie-Louise); H.A. Verbrugh (Henri)

    1996-01-01

    textabstractTo determine the postantibiotic effect of aminoglycosides, two methods are currently being used to remove the test drug: repeated washing and dilution. An enzymatic inactivation method of removing gentamicin and tobramycin was developed and compared with the dilution

  2. novel 6'-n-aminoglycoside acetyltransferase AAC(6')-Iaj from a clinical isolate of Pseudomonas aeruginosa.

    Science.gov (United States)

    Tada, Tatsuya; Miyoshi-Akiyama, Tohru; Shimada, Kayo; Shimojima, Masahiro; Kirikae, Teruo

    2013-01-01

    Pseudomonas aeruginosa NCGM1588 has a novel chromosomal class 1 integron, In151, which includes the aac(6')-Iaj gene. The encoded protein, AAC(6')-Iaj, was found to consist of 184 amino acids, with 70% identity to AAC(6')-Ia. Escherichia coli transformed with a plasmid containing the aac(6')-Iaj gene acquired resistance to all aminoglycosides tested except gentamicin. Of note, aac(6')-Iaj contributed to the resistance to arbekacin. Thin-layer chromatography revealed that AAC(6')-Iaj acetylated all aminoglycosides tested except gentamicin. These findings indicated that AAC(6')-Iaj is a functional acetyltransferase that modifies the amino groups at the 6' positions of aminoglycosides and contributes to aminoglycoside resistance of P. aeruginosa NCGM1588, including arbekacin.

  3. OCCURRENCE OF HIGH-LEVEL AMINOGLYCOSIDE RESISTANCE IN ENVIRONMENTAL ISOLATES OF ENTEROCOCCI

    Science.gov (United States)

    High-level resistance fo aminoglycosides was observed in environmental isolates of enterococci. Various aquatic habitats, including agricultural runoff, creeks, rivers, wastewater, and wells, were analyzed. Strains of Enterococcus faecalis, e.faecium, E. gallinarum, and other Ent...

  4. 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

  5. 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...... as measured by reduced minimum inhibitory concentrations, whereas GroEL/GroES overexpression did not increase minimum inhibitory concentrations. Our observations establish misfolding of cytosolic proteins as an effect of aminoglycoside action and reveal that chaperones, chaperonins in particular, help...

  6. Identification of aac(2')-I type b aminoglycoside-modifying enzyme genes in resistant Acinetobacter baumannii.

    Science.gov (United States)

    Lin, T; Tang, C G; Li, Q H; Ji, J; Ge, H Y; Zhang, X Y; Sun, H P

    2015-03-13

    The aim of this study was to investigate the mechanism underlying the drug resistance of Acinetobacter baumannii toward aminoglycosides. A total of 32 A. baumannii strains were identified by molecular identification and subsequently isolated. The isolates were then amplified by polymerase chain reaction to analyze the 9 aminoglycoside-modifying enzyme genes and 7 16S rRNA methylase genes. Five types of aminoglycoside-modifying enzyme genes and 1 type of 16S rRNA methylase gene were detected in the 32 drug-resistant A. baumannii strains. Positive genes included 7 detection modes, of which the all-6-gene-positive mode aac(2')-Ib+aac(3)-I+aac(6')-Ib+ant(3'')-I+aph(3')-I+armA exhibited the largest number of strains (12, 37.5%). The resistance of A. baumannii against aminoglycosides resulted from the presence of 5 types of aminoglycoside-modifying enzyme genes and the 16S rRNA methylase gene armA. This study is the first to isolate the aac(2')-Ib aminoglycoside-modifying enzyme gene from A. baumannii in a domestic clinical setting.

  7. 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.

  8. Functional characterization of MexXY and OpmG in aminoglycoside efflux in Pseudomonas aeruginosa.

    Science.gov (United States)

    Chuanchuen, Rungtip; Wannaprasat, Wechsiri; Schweizer, Herbert P

    2008-01-01

    MexXY is an active efflux system that contributes to intrinsic resistance to aminoglycosides in Pseudomonas aeruginosa. MexXY can function in combination with OprM in aminoglycoside efflux but may also functionally associate with another as yet unidentified outer membrane channel. The possible role of OpmG as a third component of MexXY in aminoglycoside efflux was investigated by construction of unmarked opmG mutants. Loss of OpmG did not have any impact on minimum inhibitory concentrations for aminoglycosides regardless of the presence of oprM, indicating that MexXY does not interact with OpmG in aminoglycoside efflux. In a clinical isolate PAJ010, (mexXY) enhanced streptomycin susceptibility but neither oprM nor opmG could, suggesting that MexXY functionally associates with an unidentified outer membrane protein for aminoglycoside efflux. Expression of an opmG-lacZ transcriptional fusion revealed that OpmG expression was neither constitutive nor inducible by gentamicin. Growth rates of wildtype P. aeruginosa and opmG mutant derivatives were not different, indicating that expression of opmG is not essential for P. aeruginosa growth.

  9. 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...

  10. Entry of aminoglycosides into renal tubular epithelial cells via endocytosis-dependent and endocytosis-independent pathways.

    Science.gov (United States)

    Nagai, Junya; Takano, Mikihisa

    2014-08-15

    Aminoglycoside antibiotics such as gentamicin and amikacin are well recognized as a clinically important antibiotic class because of their reliable efficacy and low cost. However, the clinical use of aminoglycosides is limited by their nephrotoxicity and ototoxicity. Nephrotoxicity is induced mainly due to high accumulation of the antibiotics in renal proximal tubular cells. Therefore, a lot of studies on characterization of the renal transport system for aminoglycosides so far reported involved various in-vivo and in-vitro techniques. Early studies revealed that aminoglycosides are taken up through adsorptive endocytosis in renal epithelial cells. Subsequently, it was found that megalin, a multiligand endocytic receptor abundantly expressed on the apical side of renal proximal tubular cells, can bind aminoglycosides and that megalin-mediated endocytosis plays a crucial role in renal accumulation of aminoglycosides. Therefore, megalin has been suggested to be a promising molecular target for the prevention of aminoglycoside-induced nephrotoxicity. On the other hand, recently, some reports have indicated that aminoglycosides are transported via a pathway that does not require endocytosis, such as non-selective cation channel-mediated entry, in cultured renal tubular cells as well as cochlear outer hair cells. In this commentary article, we review the cellular transport of aminoglycosides in renal epithelial cells, focusing on endocytosis-dependent and -independent pathways. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Chitosan conjugation enables intracellular bacteria susceptible to aminoglycoside antibiotic.

    Science.gov (United States)

    Mu, Haibo; Niu, Hong; Wang, Dongdong; Sun, Feifei; Sun, Yuelin; Duan, Jinyou

    2016-11-01

    Most chronic infections are difficult to eradicate because bacteria capable of surviving in host-infected cells may be protected from the killing actions of antibiotics, leading to therapy failures and disease relapses. Here we demonstrated that covalent-coupling chitosan to streptomycin significantly improved intracellular bactericidal capacity towards multiple organisms within phagocytic or nonphagocytic cells. Structure-activity relationship investigations indicated that antibiotic contents, molecular size and positive charges of the conjugate were the key to retain this intracellular bactericidal activity. Mechanistic insight demonstrated the conjugate was capable to target and eliminate endocytic or endosomal escaped bacteria through facilitating the direct contact between the antibiotic and intracellular organism. In vivo acute infection models indicated that compared to equal dose of the antibiotic, chitosan-streptomycin (C-S) conjugate and especially the human serum album binding chitosan-streptomycin conjugate (HCS) complex formed by human serum album and C-S conjugate greatly decreased the bacteria burden in the spleen and liver in both wild type and immuno-suppressive mice. Furthermore, the HCS complex remarkably reduced mortality of infected TLR2 deficient mice, mimicking immune-compromised persons who were more susceptible to bacterial infections. These findings might open up a new avenue to combat intracellular bacterial infection by aminoglycosides antibiotics at a lower effective dose. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Functional hair cell mechanotransducer channels are required for aminoglycoside ototoxicity.

    Directory of Open Access Journals (Sweden)

    Abdelrahman Alharazneh

    Full Text Available Aminoglycosides (AG are commonly prescribed antibiotics with potent bactericidal activities. One main side effect is permanent sensorineural hearing loss, induced by selective inner ear sensory hair cell death. Much work has focused on AG's initiating cell death processes, however, fewer studies exist defining mechanisms of AG uptake by hair cells. The current study investigated two proposed mechanisms of AG transport in mammalian hair cells: mechanotransducer (MET channels and endocytosis. To study these two mechanisms, rat cochlear explants were cultured as whole organs in gentamicin-containing media. Two-photon imaging of Texas Red conjugated gentamicin (GTTR uptake into live hair cells was rapid and selective. Hypocalcemia, which increases the open probability of MET channels, increased AG entry into hair cells. Three blockers of MET channels (curare, quinine, and amiloride significantly reduced GTTR uptake, whereas the endocytosis inhibitor concanavalin A did not. Dynosore quenched the fluorescence of GTTR and could not be tested. Pharmacologic blockade of MET channels with curare or quinine, but not concanavalin A or dynosore, prevented hair cell loss when challenged with gentamicin for up to 96 hours. Taken together, data indicate that the patency of MET channels mediated AG entry into hair cells and its toxicity. Results suggest that limiting permeation of AGs through MET channel or preventing their entry into endolymph are potential therapeutic targets for preventing hair cell death and hearing loss.

  13. rRNA chemical groups required for aminoglycoside binding.

    Science.gov (United States)

    Blanchard, S C; Fourmy, D; Eason, R G; Puglisi, J D

    1998-05-26

    Through an affinity chromatography based modification-interference assay, we have identified chemical groups within Escherichia coli 16S ribosomal RNA sequence that are required for binding the aminoglycoside antibiotic paromomycin. Paromomycin was covalently linked to solid support via a nine atom spacer from the 6"'-amine of ring IV, and chemical modifications to an A-site oligonucleotide that disrupted binding were identified. Positions in the RNA oligonucleotide that correspond to G1405(N7), G1491(N7), G1494(N7), A1408(N7), A1493(N7), A1408(N1), A1492(N1), and A1493(N1), as well as the pro-R phosphate oxygens of A1492 and A1493 in 16S rRNA are chemical groups that are essential for a high-affinity RNA-paromomycin interaction. These data are consistent with genetic, biochemical, and structural studies related to neomycin-class antibiotics and provide additional information for establishing an exact model for their interaction with the ribosome.

  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. 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.

  16. Local mechanisms for loud sound-enhanced aminoglycoside entry into outer hair cells.

    Science.gov (United States)

    Li, Hongzhe; Kachelmeier, Allan; Furness, David N; Steyger, Peter S

    2015-01-01

    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 min prior to fixation. The degree of TTS was assessed by comparing auditory brainstem responses (ABRs) 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 synergy.

  17. 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

  18. 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.

  19. Assessment of aminoglycoside-induced hearing impairment in hospitalized neonates by TEOAE.

    Science.gov (United States)

    Naeimi, Mohammad; Maamouri, Gholamali; Boskabadi, Hassan; Golparvar, Sadegh; Taleh, Mohamadreza; Esmaeeli, Habib; Khademi, Javad

    2009-12-01

    Aminoglycosides, as potent bactericidal antibiotics against aerobic gram-negative infections, is still widely used, especially in NICU patients, despite their known potential ototoxic effects. To evaluate the potential of transient evoked otoacoustic emissions (TEOAEs) in early identification of decreased hearing sensitivity in hospitalized neonates receiving aminoglycosides for severe gram-negative infections. Fifty (50) neonates treated with intravenous gentamicin (5 mg/kg/day) or amikacin (15 mg/kg/day) were tested with TEOAE in the beginning and the end of aminoglycoside therapeutic course. There were 23 males and 27 females, ranging from 29 to 40 weeks (mean: 36 weeks). The treatment duration was 3-30 days (in 26 neonates up to 7 days - group A, and in 24 neonates higher than 7 days - group B). In group A, no statistically significant difference in the mean response level was found between the onset and the end of treatment course (p > 0.001). In group B, a statistically significant difference in the mean response level was found between the onset and the end of treatment course, especially at high frequency region (p < 0.001). TEOAE is sensitive enough to detect early aminoglycoside ototoxicity. As this test is simple to perform, non-invasive and reliable, so we suggest that TEOAE test should be performed in NICU as routine for monitoring cochlear function to prevent permanent hearing loss especially in those who are receiving aminoglycoside for more than 7 days.

  20. 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....

  1. Oxidative stress induction of the MexXY multidrug efflux genes and promotion of aminoglycoside resistance development in Pseudomonas aeruginosa.

    Science.gov (United States)

    Fraud, Sebastien; Poole, Keith

    2011-03-01

    Exposure to reactive oxygen species (ROS) (e.g., peroxide) was shown to induce expression of the PA5471 gene, which was previously shown to be required for antimicrobial induction of the MexXY components of the MexXY-OprM multidrug efflux system and aminoglycoside resistance determinant in Pseudomonas aeruginosa. mexXY was also induced by peroxide exposure, and this too was PA5471 dependent. The prospect of ROS promoting mexXY expression and aminoglycoside resistance recalls P. aeruginosa infection of the chronically inflamed lungs of cystic fibrosis (CF) patients, where the organism is exposed to ROS and where MexXY-OprM predominates as the mechanism of aminoglycoside resistance. While ROS did not enhance aminoglycoside resistance in vitro, long-term (8-day) exposure of P. aeruginosa to peroxide (mimicking chronic in vivo ROS exposure) increased aminoglycoside resistance frequency, dependent upon PA5471 and mexXY. This enhanced resistance frequency was also seen in a mutant strain overexpressing PA5471, in the absence of peroxide, suggesting that induction of PA5471 by peroxide was key to peroxide enhancement of aminoglycoside resistance frequency. Resistant mutants selected following peroxide exposure were typically pan-aminoglycoside-resistant, with mexXY generally required for this resistance. Moreover, PA5471 was required for mexXY expression and aminoglycoside resistance in these as well as several CF isolates examined.

  2. Characterization of Aminoglycoside Resistance and Virulence Genes among Enterococcus spp. Isolated from a Hospital in China

    Directory of Open Access Journals (Sweden)

    Wanxiang Li

    2015-03-01

    Full Text Available This study investigated the aminoglycoside resistance phenotypes and genotypes, as well as the prevalence of virulence genes, in Enterococcus species isolated from clinical patients in China. A total of 160 enterococcal isolates from various clinical samples collected from September 2013 to July 2014 were identified to the species level using the VITEK-2 COMPACT system. The antimicrobial susceptibilities of the identified Enterococcus strains were determined by the Kirby-Bauer (K-B disc diffusion method. PCR-based assays were used to detect the aminoglycoside resistance and virulence genes in all enterococcal isolates. Of 160 Enterococcus isolates, 105 were identified as E. faecium, 35 as E. faecalis, and 20 isolates were classified as “other” Enterococcus species. High-level aminoglycoside resistance (HLAR for gentamicin, streptomycin, and both antibiotics was identified in 58.8, 50, and 34.4% of strains, respectively. The most common virulence gene (50.6% of isolates was efaA, followed by asa1 (28.8%. The most prevalent aminoglycoside resistance genes were aac(6'-Ie-aph(2'', aph(2'-Id, aph(3'-IIIa, and ant(6'-Ia, present in 49.4%, 1.3%, 48.8% and 31.3% of strains, respectively. Overall, E. faecium and E. faecalis were most frequently associated with hospital-acquired enterococcal infections in Zhejiang Province. All aminoglycoside resistance genes, except aph(2''-Id, were significantly more prevalent in HLAR strains than amongst high level aminoglycoside susceptible (HLAS strains, while there was no significant difference between HLAR and HLAS strains in regard to the prevalence of virulence genes, apart from esp, therefore, measures should be taken to manage infections caused by multi-drug resistant Enterococcus species.

  3. Characterization of Aminoglycoside Resistance and Virulence Genes among Enterococcus spp. Isolated from a Hospital in China

    Science.gov (United States)

    Li, Wanxiang; Li, Jing; Wei, Quhao; Hu, Qingfeng; Lin, Xiaowei; Chen, Mengquan; Ye, Renji; Lv, Huoyang

    2015-01-01

    This study investigated the aminoglycoside resistance phenotypes and genotypes, as well as the prevalence of virulence genes, in Enterococcus species isolated from clinical patients in China. A total of 160 enterococcal isolates from various clinical samples collected from September 2013 to July 2014 were identified to the species level using the VITEK-2 COMPACT system. The antimicrobial susceptibilities of the identified Enterococcus strains were determined by the Kirby-Bauer (K-B) disc diffusion method. PCR-based assays were used to detect the aminoglycoside resistance and virulence genes in all enterococcal isolates. Of 160 Enterococcus isolates, 105 were identified as E. faecium, 35 as E. faecalis, and 20 isolates were classified as “other” Enterococcus species. High-level aminoglycoside resistance (HLAR) for gentamicin, streptomycin, and both antibiotics was identified in 58.8, 50, and 34.4% of strains, respectively. The most common virulence gene (50.6% of isolates) was efaA, followed by asa1 (28.8%). The most prevalent aminoglycoside resistance genes were aac(6')-Ie-aph(2''), aph(2')-Id, aph(3')-IIIa, and ant(6')-Ia, present in 49.4%, 1.3%, 48.8% and 31.3% of strains, respectively. Overall, E. faecium and E. faecalis were most frequently associated with hospital-acquired enterococcal infections in Zhejiang Province. All aminoglycoside resistance genes, except aph(2'')-Id, were significantly more prevalent in HLAR strains than amongst high level aminoglycoside susceptible (HLAS) strains, while there was no significant difference between HLAR and HLAS strains in regard to the prevalence of virulence genes, apart from esp, therefore, measures should be taken to manage infections caused by multi-drug resistant Enterococcus species. PMID:25768240

  4. Role of the MexXY multidrug efflux pump in moderate aminoglycoside resistance in Pseudomonas aeruginosa isolates from Pseudomonas mastitis.

    Science.gov (United States)

    Chuanchuen, Rungtip; Wannaprasat, Wechsiri; Ajariyakhajorn, Kittisak; Schweizer, Herbert P

    2008-08-01

    The contribution of the MexXY multidrug efflux system to aminoglycoside resistance was investigated in 18 clinical isolates of Pseudomonas aeruginosa obtained from dairy cows with Pseudomonas mastitis. All of the isolates expressed MexXY as determined by reverse transcription-PCR. The loss of mexXY resulted in increased susceptibility (two- to 16-fold decline in MIC) to aminoglycosides, confirming the contribution of this system in aminoglycoside resistance in these strains. As the impact of DeltamexXY varied, overexpression of MexXY alone is not sufficient for aminoglycoside resistance. Expression of mexXY also varied and did not strictly correlate with aminoglycoside insusceptibility. Transcription levels of mexY were independent on mutations in mexZ, suggesting the existence of additional regulatory mechanisms other than mexZ.

  5. 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...... sequencing of the gene encoding translation initiation factor 2. Fourteen of the 15 isolates were identical, as evaluated by their antibiograms and by all these typing methods, This epidemic strain harboured the aminoglycoside resistance genes aac(3)-II and ant(3")-I, with the latter located in tandem...

  6. A minimum structure of aminoglycosides that causes an initiation shift of trans-translation

    OpenAIRE

    Konno, Takayuki; Takahashi, Toshiharu; Kurita, Daisuke; Muto, Akira; Himeno, Hyouta

    2004-01-01

    Trans-translation is an unusual translation in which transfer-messenger RNA plays a dual function—as a tRNA and an mRNA—to relieve the stalled translation on the ribosome. It has been shown that paromomycin, a typical member of a 4,5-disubstituted class of aminoglycosides, causes a shift of the translation-resuming point on the tmRNA by −1 during trans-translation. To address the molecular basis of this novel effect, we examined the effects of various aminoglycosides that can bind around the ...

  7. Kinetic and Structural Analysis of Bisubstrate Inhibition of the Salmonella enterica Aminoglycoside 6′-N-Acetyltransferase†,‡

    Science.gov (United States)

    Magalhães, Maria L. B.; Vetting, Matthew W.; Gao, Feng; Freiburger, Lee; Auclair, Karine; Blanchard, John S.

    2011-01-01

    Aminoglycosides are antibacterial compounds that act by binding to the A site of the small 30S bacterial ribosomal subunit and inhibiting protein translation. Clinical resistance to aminoglycosides is generally the result of the expression of enzymes that covalently modify the antibiotic, including phosphorylation, adenylylation, and acetylation. Bisubstrate analogs for the aminoglycoside N-acetyl-transferases are nanomolar inhibitors of Enterococcus faecium AAC(6′)-Ii. However, in the case of the Salmonella enterica aac(6′)-Iy-encoded aminoglycoside N-acetyltransferase, we demonstrate that a series of bisubstrate analogs are only micromolar inhibitors. In contrast to studies with AAC(6′)-Ii, the inhibition constants toward AAC(6′)-Iy are essentially independent of both the identity of the aminoglycoside component of the bisubstrate and the number of carbon atoms that are used to link the CoA and aminoglycoside components. The patterns of inhibition suggest that the CoA portion of the bisubstrate analog can bind to the enzyme–aminoglycoside substrate complex and that the aminoglycoside portion can bind to the enzyme–CoA product complex. However, at the high concentrations of bisubstrate analog used in crystallization experiments, we could crystallize and solve the three-dimensional structure of the enzyme–bisubstrate complex. The structure reveals that both the CoA and aminoglycoside portions bind in essentially the same positions as those previously observed for the enzyme–CoA–ribostamycin complex, with only a modest adjustment to accommodate the “linker”. These results are compared to previous studies of the interaction of similar bisubstrate analogs with other aminoglycoside N-acetyltransferases. PMID:18095712

  8. Why are ototopical aminoglycosides still first-line therapy for chronic suppurative otitis media? A systematic review and discussion of aminoglycosides versus quinolones.

    Science.gov (United States)

    Harris, A S; Elhassan, H A; Flook, E P

    2016-01-01

    This systematic review aimed to establish that quinolones are as effective as aminoglycosides when used to treat chronic suppurative otitis media. The review included good quality, randomised, controlled trials on human subjects, published in English, that compared topical aminoglycosides with topical quinolones for the treatment of chronic suppurative otitis media. Nine trials met the criteria. Two studies showed a higher clinical cure rate in the quinolone group (93 per cent vs 71 per cent, p = 0.04, and 76 per cent vs 52 per cent, p = 0.009). Four studies showed no statistically significant difference in clinical outcome. A significant difference in microbiological clearance in favour of quinolones was shown in two studies (88 per cent vs 30 per cent, p otitis media and when used as prophylaxis post-myringotomy. Topical quinolones should be considered a first-line treatment for these patients.

  9. Rapid determination of bacterial aminoglycoside resistance in environmental samples using membrane electrospray ionization mass spectrometry.

    Science.gov (United States)

    Fan, Liusheng; Ke, Ming; Yuan, Min; Pu, Ji; Li, Juan; Lu, Jinxing; Xu, Jianguo; Zhang, Mei; Xu, Wei

    2016-08-01

    Antibiotic resistance in pathogenic bacteria is becoming a global public health problem, such as aminoglycoside resistance encoded by the armA gene. Although many methods have been reported, rapid analysis of environmental samples is still challenging. A rapid analytical method was developed in this study to determine bacterial aminoglycoside resistance using membrane electrospray ionization mass spectrometry (MESI-MS). Precursor/product-ion pairs of ArmA unique peptides were detected with minimal sample preparation. Standard peptides were synthesized and used for developing and validating the methodology, and then the method was verified by both ArmA positive and ArmA negative simulated environmental samples. A rapid method for determination of bacterial aminoglycoside resistance was developed using MESI-MS/MS. The bacterial cultural time was optimized to 2 hours, and the precision, accuracy and recovery of this method were investigated. The peptide IHSSTNER (IR-8) unique to ArmA in simulated environmental samples can be successfully identified within 3 hours. The novel assay offered a rapid method to determine bacterial aminoglycoside resistance with high sensitivity, accuracy and precision in simulated environmental samples. This method could also be applied to identify other drug-resistance proteins in clinical/environmental samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. 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.)

  11. 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.

  12. Aminoglycoside-induced hearing loss in HIV-positive and HIV ...

    African Journals Online (AJOL)

    Of 115 patients who were genetically screened, none had MT-RNR1 mutations. Conclusion. Ototoxic hearing loss is common in MDR-TB patients treated with aminoglycosides. HIV-positive patients are at increased risk of ototoxicity. Auditory monitoring and auditory rehabilitation should be an integral part of the package of ...

  13. 21 CFR 173.170 - Aminoglycoside 3′-phospho-trans-ferase II.

    Science.gov (United States)

    2010-04-01

    ... development of genetically modified cotton, oilseed rape, and tomatoes in accordance with the following... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aminoglycoside 3â²-phospho-trans-ferase II. 173.170 Section 173.170 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  14. 21 CFR 573.130 - Aminoglycoside 3′-phospho- transferase II.

    Science.gov (United States)

    2010-04-01

    ... genetically modified cotton, oilseed rape, and tomatoes in accordance with the following prescribed conditions... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aminoglycoside 3â²-phospho- transferase II. 573.130 Section 573.130 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

  15. Involvement of an active efflux system in the natural resistance of Pseudomonas aeruginosa to aminoglycosides.

    Science.gov (United States)

    Aires, J R; Köhler, T; Nikaido, H; Plésiat, P

    1999-11-01

    A mutant, named 11B, hypersusceptible to aminoglycosides, tetracycline, and erythromycin was isolated after Tn501 insertion mutagenesis of Pseudomonas aeruginosa PAO1. Cloning and sequencing experiments showed that 11B was deficient in an, at that time, unknown active efflux system that contains homologs of MexAB. This locus also contained a putative regulatory gene, mexZ, transcribed divergently from the efflux operon. Introduction of a recombinant plasmid that carries the genes of the efflux system restored the resistance of 11B to parental levels, whereas overexpression of these genes strongly increased the MICs of substrate antibiotics for the PAO1 host. Antibiotic accumulation studies confirmed that this new system is an energy-dependent active efflux system that pumps out aminoglycosides. Furthermore, this system appeared to function with an outer membrane protein, OprM. While the present paper was being written and reviewed, genes with a sequence identical to our pump genes, mexXY of P. aeruginosa, have been reported to increase resistance to erythromycin, fluoroquinolones, and organic cations in Escherichia coli hosts, although efflux of aminoglycosides was not examined (Mine et al., Antimicrob. Agents Chemother. 43:415-417, 1999). Our study thus shows that the MexXY system plays an important role in the intrinsic resistance of P. aeruginosa to aminoglycosides. Although overexpression of MexXY increased the level of resistance to fluoroquinolones, disruption of the mexXY operon in P. aeruginosa had no detectable effect on susceptibility to these agents.

  16. 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

    sequencing of the gene encoding translation initiation factor 2. Fourteen of the 15 isolates were identical, as evaluated by their antibiograms and by all these typing methods, This epidemic strain harboured the aminoglycoside resistance genes aac(3)-II and ant(3")-I, with the latter located in tandem...

  17. A minimum structure of aminoglycosides that causes an initiation shift of trans-translation.

    Science.gov (United States)

    Konno, Takayuki; Takahashi, Toshiharu; Kurita, Daisuke; Muto, Akira; Himeno, Hyouta

    2004-01-01

    Trans-translation is an unusual translation in which transfer-messenger RNA plays a dual function--as a tRNA and an mRNA--to relieve the stalled translation on the ribosome. It has been shown that paromomycin, a typical member of a 4,5-disubstituted class of aminoglycosides, causes a shift of the translation-resuming point on the tmRNA by -1 during trans-translation. To address the molecular basis of this novel effect, we examined the effects of various aminoglycosides that can bind around the A site of the small subunit of the ribosome on trans-translation in vitro. Tobramycin and gentamicin, belonging to the 4,6-disubstituted class of aminoglycosides having rings I and II similar to those in the 4,5-disubstituted class, possess similar effects. Neamine, which has only rings I and II, a common structure shared by 4,5- and 4,6-disubstituted classes of aminoglycosides, was sufficient to cause an initiation shift of trans-translation. In contrast, streptomycin or hygromycin B, lacking ring I, did not cause an initiation shift. The effect of each aminoglycoside on trans-translation coincides with that on conformational change in the A site of the small subunit of the ribosome revealed by recent structural studies: paromomycin, tobramycin and geneticin which is categorized into the gentamicin subclass, but not streptomycin and hygromycin B, flip out two conserved adenine bases at 1492 and 1493 from the A site helix. The pattern of initiation shifts by paromomycin fluctuates with variation of mutations introduced into a region upstream of the initiation point.

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

    Science.gov (United States)

    Islam, S; Oh, H; Jalal, S; Karpati, F; Ciofu, O; Høiby, N; Wretlind, B

    2009-01-01

    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 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. aeruginosa isolates over the 3-year period. In several isolates, expression of the PA5471 gene product might have some effect on elevated MICs of aminoglycosides. Inactivation of rplY, galU and/or nuoG may explain the gradual increase in MICs of aminoglycosides in laboratory mutants but probably not in the CF environment, as rplY and galU were unaltered in all isolates, and nuoG was not expressed in only one isolate. No 16S rRNA A-site mutations were found in any of the four copies of the gene in 13 investigated isolates.

  19. Evaluation of automated systems for aminoglycosides and fluoroquinolones susceptibility testing for Carbapenem-resistant Enterobacteriaceae

    Directory of Open Access Journals (Sweden)

    Zhichang Zhao

    2017-08-01

    Full Text Available Abstract Background Automated systems (MicroScan WalkAway 96 Plus, Phoenix 100, and Vitek 2 Compact are widely used in clinical laboratories nowadays. The aim of this study is to evaluate the performance of these three systems for susceptibility testing of aminoglycosides and fluoroquinolones against Carbapenem-resistant Enterobacteriaceae (CRE. Methods A total of 75 CRE isolates were used in this study. Quinolone resistance determinants (QRDs (qnrA, qnrB, qnrC, qnrD, qnrS, aac(6′-Ib-cr, oqxAB and qepA and aminoglycoside resistance determinants (ARDs (aac(6′-Ib, armA, npmA, rmtA, rmtB, rmtC, rmtD and rmtE of these CRE were screened by PCR. The MICs of aminoglycosides (gentamicin and amikacin and fluoroquinolones (ciprofloxacin and levofloxacin to CRE obtained with the automated systems were compared with the reference method (agar dilution method. Results Totally, 97.3% (73/75 of CRE harbored QRDs. The qnr gene was the most common QRD determinant identified in 68 (96.7%, followed by aac (6′-Ib-cr in 56 (74.7%, oqxAB in 23 (30.7%, and qepA in 2 (2.7%, respectively. 22.7% (17/75 of CRE harbored ARD determinants. rmtA, rmtB and npmA were identified among these isolates in 6 (8.0%, 6 (8.0% and 5 (6.7%, respectively. A total of 900 results were obtained in this study. Overall, the total error rate was 9.89%. Twenty-eight very major errors (3.11%, 22 major errors (2.44% and 39 minor errors (4.33% were identified against agar dilution method. The very major errors were almost evenly distributed between results for fluoroquinolones (2.89% and aminoglycosides (3.33%, while the major errors and minor errors were more commonly found in the results of fluoroquinolones (3.11% and 6.44%, respectively than aminoglycosides (1.78% and 2.22%, respectively. Conclusions Our study shows that testing difficulties in susceptibility testing do exist in automated systems. We suggest clinical laboratories using automated systems should consider using a second

  20. Novel 6′-N-Aminoglycoside Acetyltransferase AAC(6′)-Iaj from a Clinical Isolate of Pseudomonas aeruginosa

    Science.gov (United States)

    Tada, Tatsuya; Miyoshi-Akiyama, Tohru; Shimada, Kayo; Shimojima, Masahiro

    2013-01-01

    Pseudomonas aeruginosa NCGM1588 has a novel chromosomal class 1 integron, In151, which includes the aac(6′)-Iaj gene. The encoded protein, AAC(6′)-Iaj, was found to consist of 184 amino acids, with 70% identity to AAC(6′)-Ia. Escherichia coli transformed with a plasmid containing the aac(6′)-Iaj gene acquired resistance to all aminoglycosides tested except gentamicin. Of note, aac(6′)-Iaj contributed to the resistance to arbekacin. Thin-layer chromatography revealed that AAC(6′)-Iaj acetylated all aminoglycosides tested except gentamicin. These findings indicated that AAC(6′)-Iaj is a functional acetyltransferase that modifies the amino groups at the 6′ positions of aminoglycosides and contributes to aminoglycoside resistance of P. aeruginosa NCGM1588, including arbekacin. PMID:23070167

  1. 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.

  2. Fitness cost and interference of Arm/Rmt aminoglycoside resistance with the RsmF housekeeping methyltransferases.

    Science.gov (United States)

    Gutierrez, Belen; Escudero, Jose A; San Millan, Alvaro; Hidalgo, Laura; Carrilero, Laura; Ovejero, Cristina M; Santos-Lopez, Alfonso; Thomas-Lopez, Daniel; Gonzalez-Zorn, Bruno

    2012-05-01

    Arm/Rmt methyltransferases have emerged recently in pathogenic bacteria as enzymes that confer high-level resistance to 4,6-disubstituted aminoglycosides through methylation of the G1405 residue in the 16S rRNA (like ArmA and RmtA to -E). In prokaryotes, nucleotide methylations are the most common type of rRNA modification, and they are introduced posttranscriptionally by a variety of site-specific housekeeping enzymes to optimize ribosomal function. Here we show that while the aminoglycoside resistance methyltransferase RmtC methylates G1405, it impedes methylation of the housekeeping methyltransferase RsmF at position C1407, a nucleotide that, like G1405, forms part of the aminoglycoside binding pocket of the 16S rRNA. To understand the origin and consequences of this phenomenon, we constructed a series of in-frame knockout and knock-in mutants of Escherichia coli, corresponding to the genotypes rsmF(+), ΔrsmF, rsmF(+) rmtC(+), and ΔrsmF rmtC(+). When analyzed for the antimicrobial resistance pattern, the ΔrsmF bacteria had a decreased susceptibility to aminoglycosides, including 4,6- and 4,5-deoxystreptamine aminoglycosides, showing that the housekeeping methylation at C1407 is involved in intrinsic aminoglycoside susceptibility in E. coli. Competition experiments between the isogenic E. coli strains showed that, contrary to expectation, acquisition of rmtC does not entail a fitness cost for the bacterium. Finally, matrix-assisted laser desorption ionization (MALDI) mass spectrometry allowed us to determine that RmtC methylates the G1405 residue not only in presence but also in the absence of aminoglycoside antibiotics. Thus, the coupling between housekeeping and acquired methyltransferases subverts the methylation architecture of the 16S rRNA but elicits Arm/Rmt methyltransferases to be selected and retained, posing an important threat to the usefulness of aminoglycosides worldwide.

  3. 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.

  4. Berberine Is a Novel Type Efflux Inhibitor Which Attenuates the MexXY-Mediated Aminoglycoside Resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Morita, Yuji; Nakashima, Ken-Ichi; Nishino, Kunihiko; Kotani, Kenta; Tomida, Junko; Inoue, Makoto; Kawamura, Yoshiaki

    2016-01-01

    The emergence and spread of multidrug-resistant P. aeruginosa infections is of great concern, as very few agents are effective against strains of this species. Methanolic extracts from the Coptidis Rhizoma (the rhizomes of Coptis japonica var. major Satake) or Phellodendri Cortex (the bark of Phellodendron chinense Schneider) markedly reduced resistance to anti-pseudomonal aminoglycosides (e.g., amikacin) in multidrug-resistant P. aeruginosa strains. Berberine, the most abundant benzylisoquinoline alkaloid in the two extracts, reduced aminoglycoside resistance of P. aeruginosa via a mechanism that required the MexXY multidrug efflux system; berberine also reduced aminoglycoside MICs in Achromobacter xylosoxidans and Burkholderia cepacia, two species that harbor intrinsic multidrug efflux systems very similar to the MexXY. Furthermore this compound inhibited MexXY-dependent antibiotic resistance of other classes including cephalosporins (cefepime), macrolides (erythromycin), and lincosamides (lincomycin) demonstrated using a pseudomonad lacking the four other major Mex pumps. Although phenylalanine-arginine beta-naphthylamide (PAβN), a well-known efflux inhibitor, antagonized aminoglycoside in a MexXY-dependent manner, a lower concentration of berberine was sufficient to reduce amikacin resistance of P. aeruginosa in the presence of PAβN. Moreover, berberine enhanced the synergistic effects of amikacin and piperacillin (and vice versa) in multidrug-resistant P. aeruginosa strains. Thus, berberine appears to be a novel type inhibitor of the MexXY-dependent aminoglycoside efflux in P. aeruginosa. As aminoglycosides are molecules of choice to treat severe infections the clinical impact is potentially important.

  5. Heterologous Expression of Chaperones from Hyperthermophilic Archaea Inhibits Aminoglycoside-Induced Protein Misfolding in Escherichia coli.

    Science.gov (United States)

    Peng, S; Chu, Z; Lu, J; Li, D; Wang, Y; Yang, S; Zhang, Y

    2017-10-01

    Aminoglycoside antibiotics affect protein translation fidelity and lead to protein aggregation and an increase in intracellular oxidative stress level as well. The overexpression of the chaperonin GroEL/GroES system promotes short-term tolerance to aminoglycosides in Escherichia coli. Here, we demonstrated that the coexpression of prefoldin or Hsp60 originating from the hyperthermophilic archaeon Pyrococcus furiosus in E. coli cells can rescue cell growth and inhibit protein aggregation induced by streptomycin exposure. The results of our study show that hyperthermophilic chaperones endow E. coli with a higher tolerance to streptomycin than the GroEL/GroES system, and that they exert better effects on the reduction of intracellular protein misfolding, indicating that these chaperones have unique features and functions.

  6. 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

    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....... 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...... not in the CF environment, as rplY and galU were unaltered in all isolates, and nuoG was not expressed in only one isolate. No 16S rRNA A-site mutations were found in any of the four copies of the gene in 13 investigated isolates....

  7. Intracellular polyamine pools, oligopeptide-binding protein A expression, and resistance to aminoglycosides in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Maria BR Acosta

    2005-11-01

    Full Text Available The role of intracellular free polyamine (putrescine and spermidine pools in multiple resistance to aminoglycoside antibiotics was investigated among in vitro selected kanamycin-resistant Escherichia coli J53 mutants expressing diminished oligopeptide-binding protein (OppA levels and/or defective ornithine decarboxylase (ODC activity. The results suggest that diminished OppA content, but not defective ODC activity expression, increased the relative concentration of free spermidine as compared to the wild type strain. Moreover, by adding exogenous polyamines or polyamine synthesis inhibitors to cultures with different mutant strains, a direct relationship between the intracellular OppA levels and resistance to kanamycin was revealed. Collectively these results further suggest a complex relation among OppA expression, aminoglycoside resistance and polyamine metabolism.

  8. Aminoglycoside Antibiotics: New Insights into the Biosynthetic Machinery of Old Drugs.

    Science.gov (United States)

    Kudo, Fumitaka; Eguchi, Tadashi

    2016-02-01

    2-Deoxystreptamine (2DOS) is the unique chemically stable aminocyclitol scaffold of clinically important aminoglycoside antibiotics such as neomycin, kanamycin, and gentamicin, which are produced by Actinomycetes. The 2DOS core can be decorated with various deoxyaminosugars to make structurally diverse pseudo-oligosaccharides. After the discovery of biosynthetic gene clusters for 2DOS-containing aminoglycoside antibiotics, the function of each biosynthetic enzyme has been extensively elucidated. The common biosynthetic intermediates 2DOS, paromamine and ribostamycin are constructed by conserved enzymes encoded in the gene clusters. The biosynthetic intermediates are then converted to characteristic architectures by unique enzymes encoded in each biosynthetic gene cluster. In this Personal Account, we summarize both common biosynthetic pathways and the pathways used for structural diversification. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Novel 3-N-Aminoglycoside Acetyltransferase Gene, aac(3)-Ic, from a Pseudomonas aeruginosa Integron

    OpenAIRE

    Riccio, Maria Letizia; Docquier, Jean-Denis; Dell'Amico, Emanuela; Luzzaro, Francesco; Amicosante, Gianfranco; Rossolini, Gian Maria

    2003-01-01

    A novel gene, aac(3)-Ic, encoding an AAC(3)-I aminoglycoside 3-N-acetyltransferase, was identified on a gene cassette inserted into a Pseudomonas aeruginosa integron that also carries a blaVIM-2 and a cmlA7 gene cassette. The aac(3)-Ic gene product is 59 and 57% identical to AAC(3)-Ia and AAC(3)-Ib, respectively, and confers resistance to gentamicin and sisomicin.

  10. Misread protein creates membrane channels: an essential step in the bactericidal action of aminoglycosides.

    OpenAIRE

    Davis, B D; Chen, L L; Tai, P C

    1986-01-01

    Among the pleiotropic effects of aminoglycosides, their irreversible uptake and their blockade of initiating ribosomes have appeared to explain their bactericidal action, while the contributions of translational misreading and membrane damage and the mechanism of that damage have remained uncertain. We now present evidence that incorporation of misread proteins into the membrane can account for the membrane damage. The bactericidal action thus appears to result from the following sequence, in...

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

    Science.gov (United States)

    Kastbjerg, Vicky G.; Hein-Kristensen, Line

    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 of antibiotics. Pinpoint isolates had decreased hemolytic activity under stagnant conditions and a changed spectrum of carbohydrate utilization compared to the wild type and isolates from normal-size colonies. Genome sequence comparison revealed that all seven pinpoint isolates had a mutation in a heme gene, and addition of heme caused the pinpoint isolates to revert to normal colony size. Triclosan-induced gentamicin-resistant isolates had mutations in several different genes, and it cannot be directly concluded how the different mutations caused gentamicin resistance. However, since many of the mutations affected proteins involved in respiration, it seems likely that the mutations affected the active transport of the antibiotic and thereby caused resistance by decreasing the amount of aminoglycoside that enters the bacterial cell. Our study emphasizes that triclosan likely has more targets than just fabI 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. PMID:24637686

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

    Science.gov (United States)

    Varma, Tarun; Saini, Ashish; Panchani, Roopal; Gupta, Nitin R.

    2013-01-01

    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. PMID:24251160

  13. 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.

  14. Rise and dissemination of aminoglycoside resistance: the aac(6′)-Ib paradigm

    Science.gov (United States)

    Ramirez, María S.; Nikolaidis, Nikolas; Tolmasky, Marcelo E.

    2013-01-01

    Enzymatic modification is a prevalent mechanism by which bacteria defeat the action of antibiotics. Aminoglycosides are often inactivated by aminoglycoside modifying enzymes encoded by genes present in the chromosome, plasmids, and other genetic elements. The AAC(6′)-Ib (aminoglycoside 6′-N-acetyltransferase type Ib) is an enzyme of clinical importance found in a wide variety of gram-negative pathogens. The AAC(6′)-Ib enzyme is of interest not only because of his ubiquity but also because of other characteristics, it presents significant microheterogeneity at the N-termini and the aac(6′)-Ib gene is often present in integrons, transposons, plasmids, genomic islands, and other genetic structures. Excluding the highly heterogeneous N-termini, there are 45 non-identical AAC(6′)-Ib related entries in the NCBI database, 32 of which have identical name in spite of not having identical amino acid sequence. While some variants conserved similar properties, others show dramatic differences in specificity, including the case of AAC(6′)-Ib-cr that mediates acetylation of ciprofloxacin representing a rare case where a resistance enzyme acquires the ability to utilize an antibiotic of a different class as substrate. Efforts to utilize antisense technologies to turn off expression of the gene or to identify enzymatic inhibitors to induce phenotypic conversion to susceptibility are under way. PMID:23730301

  15. Rise and dissemination of aminoglycoside resistance: the aac(6')-Ib paradigm.

    Science.gov (United States)

    Ramirez, María S; Nikolaidis, Nikolas; Tolmasky, Marcelo E

    2013-01-01

    Enzymatic modification is a prevalent mechanism by which bacteria defeat the action of antibiotics. Aminoglycosides are often inactivated by aminoglycoside modifying enzymes encoded by genes present in the chromosome, plasmids, and other genetic elements. The AAC(6')-Ib (aminoglycoside 6'-N-acetyltransferase type Ib) is an enzyme of clinical importance found in a wide variety of gram-negative pathogens. The AAC(6')-Ib enzyme is of interest not only because of his ubiquity but also because of other characteristics, it presents significant microheterogeneity at the N-termini and the aac(6')-Ib gene is often present in integrons, transposons, plasmids, genomic islands, and other genetic structures. Excluding the highly heterogeneous N-termini, there are 45 non-identical AAC(6')-Ib related entries in the NCBI database, 32 of which have identical name in spite of not having identical amino acid sequence. While some variants conserved similar properties, others show dramatic differences in specificity, including the case of AAC(6')-Ib-cr that mediates acetylation of ciprofloxacin representing a rare case where a resistance enzyme acquires the ability to utilize an antibiotic of a different class as substrate. Efforts to utilize antisense technologies to turn off expression of the gene or to identify enzymatic inhibitors to induce phenotypic conversion to susceptibility are under way.

  16. 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.

  17. 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.

  18. Aminoglycosides resistance in clinical isolates of Staphylococcus aureus from a University Hospital in Bialystok, Poland.

    Directory of Open Access Journals (Sweden)

    Katarzyna Kaczyńska

    2008-06-01

    Full Text Available Staphylococcus aureus obtained from a University Hospital in Poland were characterized in relation to resistance to aminoglycoside antibiotics and the distribution of the genes encoding the most clinically relevant aminoglycoside modifying enzymes (AMEs. Of a total of 118 S. aureus, 45 (38.1% isolates were found to be resistant to at least one of the tested antibiotics. All aminoglycoside resistant isolates except one 44 (97.8% were resistant to kanamycin. The majority of strains 37 (82.2% and 32 (71.1% expressed resistance to neomycin and tobramycin, respectively. Eleven strains (24.4% were resistant to gentamicin or amikacin. All S. aureus strains were sensitive to netilmicin. The most prevalent resistance gene was aac(6'-Ie+aph(2' found in 13 (28.9% strains and 12 (26.7% isolates carried ant(4'-Ia gene, whilst aph(3'-IIIa gene was detected in only 7 (15.6% isolates. Additionally, the ant(6-Ia and str genes were detected in 14 (31.1% and 2 (4.4% strains, respectively. Ten (22.2% strains resistant to amikacin, tobramycin, kanamycin or neomycin did not harbor any of the above-noted genes.

  19. A rapid method for detection of five known mutations associated with aminoglycoside-induced deafness

    Science.gov (United States)

    Bardien, Soraya; Human, Hannique; Harris, Tashneem; Hefke, Gwynneth; Veikondis, Rene; Schaaf, H Simon; van der Merwe, Lize; Greinwald, John H; Fagan, Johan; de Jong, Greetje

    2009-01-01

    Background South Africa has one of the highest incidences of multidrug-resistant tuberculosis (MDR-TB) in the world. Concomitantly, aminoglycosides are commonly used in this country as a treatment against MDR-TB. To date, at least five mutations are known to confer susceptibility to aminoglycoside-induced hearing loss. The aim of the present study was to develop a rapid screening method to determine whether these mutations are present in the South African population. Methods A multiplex method using the SNaPshot technique was used to screen for five mutations in the MT-RNR1 gene: A1555G, C1494T, T1095C, 961delT+C(n) and A827G. A total of 204 South African control samples, comprising 98 Mixed ancestry and 106 Black individuals were screened for the presence of the five mutations. Results A robust, cost-effective method was developed that detected the presence of all five sequence variants simultaneously. In this pilot study, the A1555G mutation was identified at a frequency of 0.9% in the Black control samples. The 961delT+C(n) variant was present in 6.6% of the Black controls and 2% of the Mixed ancestry controls. The T1095C, C1494T and A827G variants were not identified in any of the study participants. Conclusion The frequency of 0.9% for the A1555G mutation in the Black population in South Africa is of concern given the high incidence of MDR-TB in this particular ethnic group. Future larger studies are warranted to determine the true frequencies of the aminoglycoside deafness mutations in the general South African population. The high frequencies of the 961delT+C(n) variant observed in the controls suggest that this change is a common non-pathogenic polymorphism. This genetic method facilitates the identification of individuals at high risk of developing hearing loss prior to the start of aminoglycoside therapy. This is important in a low-resource country like South Africa where, despite their adverse side-effects, aminoglycosides will continue to be used

  20. A rapid method for detection of five known mutations associated with aminoglycoside-induced deafness

    Directory of Open Access Journals (Sweden)

    Greinwald John H

    2009-01-01

    Full Text Available Abstract Background South Africa has one of the highest incidences of multidrug-resistant tuberculosis (MDR-TB in the world. Concomitantly, aminoglycosides are commonly used in this country as a treatment against MDR-TB. To date, at least five mutations are known to confer susceptibility to aminoglycoside-induced hearing loss. The aim of the present study was to develop a rapid screening method to determine whether these mutations are present in the South African population. Methods A multiplex method using the SNaPshot technique was used to screen for five mutations in the MT-RNR1 gene: A1555G, C1494T, T1095C, 961delT+C(n and A827G. A total of 204 South African control samples, comprising 98 Mixed ancestry and 106 Black individuals were screened for the presence of the five mutations. Results A robust, cost-effective method was developed that detected the presence of all five sequence variants simultaneously. In this pilot study, the A1555G mutation was identified at a frequency of 0.9% in the Black control samples. The 961delT+C(n variant was present in 6.6% of the Black controls and 2% of the Mixed ancestry controls. The T1095C, C1494T and A827G variants were not identified in any of the study participants. Conclusion The frequency of 0.9% for the A1555G mutation in the Black population in South Africa is of concern given the high incidence of MDR-TB in this particular ethnic group. Future larger studies are warranted to determine the true frequencies of the aminoglycoside deafness mutations in the general South African population. The high frequencies of the 961delT+C(n variant observed in the controls suggest that this change is a common non-pathogenic polymorphism. This genetic method facilitates the identification of individuals at high risk of developing hearing loss prior to the start of aminoglycoside therapy. This is important in a low-resource country like South Africa where, despite their adverse side-effects, aminoglycosides will

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

    Science.gov (United States)

    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

  2. Kinetic and mutagenic characterization of the chromosomally encoded Salmonella enterica AAC(6')-Iy aminoglycoside N-acetyltransferase.

    Science.gov (United States)

    Magnet, S; Lambert, T; Courvalin, P; Blanchard, J S

    2001-03-27

    The chromosomally encoded aminoglycoside N-acetyltransferase, AAC(6')-Iy, from Salmonella enterica confers resistance toward a number of aminoglycoside antibiotics. The structural gene was cloned and expressed and the purified enzyme existed in solution as a dimer of ca. 17 000 Da monomers. Acetyl-CoA was the preferred acyl donor, and most therapeutically important aminoglycosides were substrates for acetylation. Exceptions are those aminoglycosides that possess a 6'-hydroxyl substituent (e.g., lividomycin). Thus, the enzyme exhibited regioselective and exclusive acetyltransferase activity to 6'-amine-containing aminoglycosides. The enzyme exhibited Michaelis-Menten kinetics for some aminoglycoside substrates but "substrate activation" with others. Kinetic studies supported a random kinetic mechanism for the enzyme. The enzyme was inactivated by iodoacetamide in a biphasic manner, with half of the activity being lost rapidly and the other half more slowly. Tobramycin, but not acetyl-CoA, protected against inactivation. Each of the three cysteine residues (C70, C109, C145) in the wild-type enzyme were carboxamidomethylated by iodoacetamide. Cysteine 109 in AAC(6')-Iy is conserved in 12 AAC(6') enzyme sequences of the major class I subfamily. Surprisingly, mutation of this residue to alanine neither abolished activity nor altered the biphasic inactivation by iodoacetamide. The maximum velocity and V/K values for a number of aminoglycosides were elevated in this single mutant, and the kinetic behavior of substrates exhibiting linear vs nonlinear kinetics was reversed. Cysteine 70 in AAC(6')-Iy is either a cysteine or a threonine residue in all 12 AAC(6') enzymes of the major class I subfamily. The double mutant, C109A/C70A, was not inactivated by iodoacetamide. The double mutant exhibited large increases in the K(m) values for both acetyl-CoA and aminoglycoside substrates, and all aminoglycoside substrates exhibited Michaelis-Menten kinetics. Solvent kinetic isotope

  3. Megalin-targeted enhanced transfection efficiency in cultured human HK-2 renal tubular proximal cells using aminoglycoside-carboxyalkyl- polyethylenimine -containing nanoplexes.

    Science.gov (United States)

    Oroojalian, Fatemeh; Rezayan, Ali Hossein; Shier, Wayne Thomas; Abnous, Khalil; Ramezani, Mohammad

    2017-05-15

    Non-viral vectors are of interest as therapeutic gene delivery agents in gene therapy, because they are simple to prepare, easy to modify and have definable safety profiles compared to viral vectors. The potential of gene therapy in the treatment of renal diseases is limited by a lack of effective kidney-targeted gene delivery systems. Aminoglycoside antibiotics gentamicin and neomycin were connected by amide linkages to carboxyl groups on carboxyalkylated-PEI 25 (25kDa PEI) or carboxyalkylated-PEI 10 (10kDa PEI). Aminoglycoside-carboxyalkylated-PEI conjugates were characterized with respect to size, surface charge density, DNA condensation ability, and buffering capacity. Polyplexes prepared by electrostatic interaction between aminoglycoside-carboxyalkylated-PEIs and enhanced green fluorescent protein-expressing (EGFP) plasmid DNA had appropriate nano-scale size (143-173nm). Their targeting potential was investigated in cultured HK-2 immortalized human cortex/proximal tubule kidney epithelial cells, which expresses megalin, a scavenger receptor that mediates endocytosis of a diverse group of ligands, including aminoglycoside antibiotics. Aminoglycoside-carboxyalkylated-PEIs significantly increased EGFP gene transfection efficiency in HK-2 cells by ∼13-fold for aminoglycoside-carboxyalkylated-PEI 25 and ∼7-fold increase for aminoglycoside-carboxyalkylated-PEI 10 relative to the corresponding PEIs without aminoglycosides. The transfection efficiency of polyplexes was dependent on the weight ratio of aminoglycoside-containing ligand in the carrier. In the presence of a range of concentrations of human serum albumin, which competes for megalin binding, aminoglycoside-carboxyalkylated-PEI-mediated transfection was reduced to background levels. These results suggest that aminoglycoside-carboxyalkylated-PEI polyplexes can target megalin-expressing kidney-derived cells in vitro resulting in improved transfection efficiency with low cytotoxicity. Copyright © 2017

  4. 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.

  5. Mechanism of Enhanced Activity of Liposome-Entrapped Aminoglycosides against Resistant Strains of Pseudomonas aeruginosa

    Science.gov (United States)

    Mugabe, Clement; Halwani, Majed; Azghani, Ali O.; Lafrenie, Robert M.; Omri, Abdelwahab

    2006-01-01

    Pseudomonas aeruginosa is inherently resistant to most conventional antibiotics. The mechanism of resistance of this bacterium is mainly associated with the low permeability of its outer membrane to these agents. We sought to assess the bactericidal efficacy of liposome-entrapped aminoglycosides against resistant clinical strains of P. aeruginosa and to define the mechanism of liposome-bacterium interactions. Aminoglycosides were incorporated into liposomes, and the bactericidal efficacies of both free and liposomal drugs were evaluated. To define the mechanism of liposome-bacterium interactions, transmission electron microscopy (TEM), flow cytometry, lipid mixing assay, and immunocytochemistry were employed. Encapsulation of aminoglycosides into liposomes significantly increased their antibacterial activity against the resistant strains used in this study (MICs of ≥32 versus ≤8 μg/ml). TEM observations showed that liposomes interact intimately with the outer membrane of P. aeruginosa, leading to the membrane deformation. The flow cytometry and lipid mixing assays confirmed liposome-bacterial membrane fusion, which increased as a function of incubation time. The maximum fusion rate was 54.3% ± 1.5% for an antibiotic-sensitive strain of P. aeruginosa and 57.8% ± 1.9% for a drug-resistant strain. The fusion between liposomes and P. aeruginosa significantly enhanced the antibiotics' penetration into the bacterial cells (3.2 ± 2.3 versus 24.2 ± 6.2 gold particles/bacterium, P ≤ 0.001). Our data suggest that liposome-entrapped antibiotics could successfully resolve infections caused by antibiotic-resistant P. aeruginosa through an enhanced mechanism of drug entry into the bacterial cells. PMID:16723560

  6. 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.

  7. 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

  8. Berberine is a novel type efflux inhibitor which attenuates the MexXY-mediated aminoglycoside resistance in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Yuji Morita

    2016-08-01

    Full Text Available The emergence and spread of multidrug-resistant P. aeruginosa infections is of great concern, as very few agents are effective against strains of this species. Methanolic extracts from the Coptidis Rhizoma (the rhizomes of Coptis japonica var. major Satake or Phellodendri Cortex (the bark of Phellodendron chinense Schneider markedly reduced resistance to anti-pseudomonal aminoglycosides (e.g. amikacin in multidrug-resistant P. aeruginosa strains. Berberine, the most abundant benzylisoquinoline alkaloid in the two extracts, reduced aminoglycoside resistance of P. aeruginosa via a mechanism that required the MexXY multidrug efflux system; berberine also reduced aminoglycoside MICs in Achromobacter xylosoxidans and Burkholderia cepacia, two species that harbor intrinsic multidrug efflux systems very similar to the MexXY. Furthermore this compound inhibited MexXY-dependent antibiotic resistance of other classes including cephalosporins (cefepime, macrolides (erythromycin, and lincosamides (lincomycin demonstrated using a pseudomonad lacking the 4 other major Mex pumps. Although phenylalanine-arginine beta-naphthylamide (PAβN, a well-known efflux inhibitor, antagonized aminoglycoside in a MexXY-dependent manner, a lower concentration of berberine was sufficient to reduce amikacin resistance of P. aeruginosa in the presence of PAβN. Moreover, berberine enhanced the synergistic effects of amikacin and piperacillin (and vice versa in multidrug-resistant P. aeruginosa strains. Thus, berberine appears to be a novel type inhibitor of the MexXY-dependent aminoglycoside efflux in P. aeruginosa. As aminoglycosides are molecules of choice to treat severe infections the clinical impact is potentially important.

  9. Mutational activation of the AmgRS two-component system in aminoglycoside-resistant Pseudomonas aeruginosa.

    Science.gov (United States)

    Lau, Calvin Ho-Fung; Fraud, Sebastien; Jones, Marcus; Peterson, Scott N; Poole, Keith

    2013-05-01

    The amgRS operon encodes a presumed membrane stress-responsive two-component system linked to intrinsic aminoglycoside resistance in Pseudomonas aeruginosa. Genome sequencing of a lab isolate showing modest pan-aminoglycoside resistance, strain K2979, revealed a number of mutations, including a substitution in amgS that produced an R182C change in the AmgS sensor kinase product of this gene. Introduction of this mutation into an otherwise wild-type strain recapitulated the resistance phenotype, while correcting the mutation in the resistant mutant abrogated the resistant phenotype, confirming that the amgS mutation is responsible for the aminoglycoside resistance of strain K2979. The amgSR182 mutation promoted an AmgR-dependent, 2- to 3-fold increase in expression of the AmgRS target genes htpX and PA5528, mirroring the impact of aminoglycoside exposure of wild-type cells on htpX and PA5528 expression. This suggests that amgSR182 is a gain-of-function mutation that activates AmgS and the AmgRS two-component system in promoting modest resistance to aminoglycosides. Screening of several pan-aminoglycoside-resistant clinical isolates of P. aeruginosa revealed three that showed elevated htpX and PA5528 expression and harbored single amino acid-altering mutations in amgS (V121G or D106N) and no mutations in amgR. Introduction of the amgSV121G mutation into wild-type P. aeruginosa generated a resistance phenotype reminiscent of the amgSR182 mutant and produced a 2- to 3-fold increase in htpX and PA5528 expression, confirming that it, too, is a gain-of-function aminoglycoside resistance-promoting mutation. These results highlight the contribution of amgS mutations and activation of the AmgRS two-component system to acquired aminoglycoside resistance in lab and clinical isolates of P. aeruginosa.

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

    Science.gov (United States)

    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

  11. Genotypic and phenotypic characteristics of aminoglycoside-resistant Mycobacterium tuberculosis isolates in Latvia.

    Science.gov (United States)

    Bauskenieks, Matiss; Pole, Ilva; Skenders, Girts; Jansone, Inta; Broka, Lonija; Nodieva, Anda; Ozere, Iveta; Kalvisa, Adrija; Ranka, Renate; Baumanis, Viesturs

    2015-03-01

    Mutations causing resistance to aminoglycosides, such as kanamycin (KAN), amikacin (AMK), and streptomycin, are not completely understood. In this study, polymorphisms of aminoglycoside resistance influencing genes such as rrs, eis, rpsL, and gidB in 41 drug-resistant and 17 pan-sensitive Mycobacterium tuberculosis clinical isolates in Latvia were analyzed. Mutation A1400G in rrs gene was detected in 92% isolates with high resistance level to KAN and diverse MIC level to AMK. Mutations in promoter region of eis were detected in 80% isolates with low-level MIC of KAN. The association of K43R mutation in rpsL gene, a mutation in the rrs gene at position 513, and various polymorphisms in gidB gene with distinct genetic lineages of M. tuberculosis was observed. The results of this study suggest that association of different controversial mutations of M. tuberculosis genes to the drug resistance phenotype should be done in respect to genetic lineages. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Origin in Acinetobacter gyllenbergii and dissemination of aminoglycoside-modifying enzyme AAC(6′)-Ih

    Science.gov (United States)

    Yoon, Eun-Jeong; Goussard, Sylvie; Nemec, Alexandr; Lambert, Thierry; Courvalin, Patrice; Grillot-Courvalin, Catherine

    2016-01-01

    Objectives The aac(6′)-Ih gene encoding aminoglycoside 6′-N-acetyltransferase type I subtype h [AAC(6′)-Ih] is plasmid-borne in Acinetobacter baumannii where it confers high-level amikacin resistance, but its origin remains unknown. We searched for the gene in the genomes of a collection of 133 Acinetobacter spp. and studied its species specificity, expression and dissemination. Methods Gene copy number was determined by quantitative PCR, expression by quantitative RT–PCR, MIC by microdilution and transfer by plasmid mobilization. Results The aac(6′)-Ih gene was present in the chromosome of the two Acinetobacter gyllenbergii of the collection and was detected in all seven A. gyllenbergii clinical isolates. They had indistinguishable flanking regions indicating that the gene was intrinsic to this species. A. baumannii PISAba23 promoters were provided by insertion of ISAba23, which disrupted the Pnative promoter in A. gyllenbergii. Both types of promoters were similarly potent in Escherichia coli and A. baumannii. Aminoglycoside MICs for A. baumannii harbouring pIP1858 were higher than for A. gyllenbergii due to gene dosage. The non-self-transferable plasmid could be mobilized to other A. baumannii cells by the broad host range plasmid RP4. Conclusions We have found the origin of aac(6′)-Ih in A. gyllenbergii, a species isolated, although rarely, in humans, and documented that dissemination of this gene is restricted to the Acinetobacter genus. PMID:26645270

  13. Protein aggregation caused by aminoglycoside action is prevented by a hydrogen peroxide scavenger.

    Science.gov (United States)

    Ling, Jiqiang; Cho, Chris; Guo, Li-Tao; Aerni, Hans R; Rinehart, Jesse; Söll, Dieter

    2012-12-14

    Protein mistranslation causes growth arrest in bacteria, mitochondrial dysfunction in yeast, and neurodegeneration in mammals. It remains poorly understood how mistranslated proteins cause such cellular defects. Here we demonstrate that streptomycin, a bactericidal aminoglycoside that increases ribosomal mistranslation, induces transient protein aggregation in wild-type Escherichia coli. We further determined the aggregated proteome using label-free quantitative mass spectrometry. To identify genes that reduce cellular mistranslation toxicity, we selected from an overexpression library protein products that increased resistance against streptomycin and kanamycin. The selected proteins were significantly enriched in members of the oxidation-reduction pathway. Overexpressing one of these proteins, alkyl hydroperoxide reductase subunit F (a protein defending bacteria against hydrogen peroxide), but not its inactive mutant suppressed aggregated protein formation upon streptomycin treatment and increased aminoglycoside resistance. This work provides in-depth analyses of an aggregated proteome caused by streptomycin and suggests that cellular defense against hydrogen peroxide lowers the toxicity of mistranslation. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis.

    Science.gov (United States)

    Smyth, Alan R; Bhatt, Jayesh; Nevitt, Sarah J

    2017-03-27

    People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often. This is an update of a previously published review. To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis. We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: 24 June 2016. All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy or toxicity or both, in people with cystic fibrosis. The two authors independently selected the studies to be included in the review and assessed the risk of bias of each study; authors also assessed the quality of the evidence using the GRADE criteria. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies. Fifteen studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants (aged 5 to 50 years) were included in this review. All studies compared once-daily dosing with thrice-daily dosing. One study had a low risk of bias for all criteria assessed; the remaining three included studies had a high risk of bias from blinding, but for other criteria were judged to have either an unclear or a low risk

  15. Audiologic monitoring of multi-drug resistant tuberculosis patients on aminoglycoside treatment with long term follow-up

    Directory of Open Access Journals (Sweden)

    Sarkar Malay

    2007-11-01

    Full Text Available Abstract Background Multi-drug resistant tuberculosis has emerged as a significant problem with the resurfacing of tuberculosis and thus the need to use the second line drugs with the resultant increased incidence of adverse effects. We discuss the effect of second line aminoglycoside anti-tubercular drugs on the hearing status of MDR-TB patients. Methods Sixty four patients were put on second line aminoglycoside anti-TB drugs. These were divided into three groups: group I, 34 patients using amikacin, group II, 26 patients using kanamycin and group III, 4 patients using capreomycin. Results Of these, 18.75% of the patients developed sensorineural hearing loss involving higher frequencies while 6.25% had involvement of speech frequencies also. All patients were seen again approximately one year after aminoglycoside discontinuation and all hearing losses were permanent with no threshold improvement. Conclusion Aminoglycosides used in MDR-TB patients may result in irreversible hearing loss involving higher frequencies and can become a hearing handicap as speech frequencies are also involved in some of the patients thus underlining the need for regular audiologic evaluation in patients of MDR-TB during the treatment.

  16. In vitro antimicrobial activity of the aminoglycoside arbekacin tested against oxacillin-resistant Staphylococcus aureus isolated in Brazilian hospitals

    Directory of Open Access Journals (Sweden)

    Julio C. R. Cordeiro

    Full Text Available Arbekacin is an aminoglycoside used in Japan for treating infections caused by gentamicin and oxacillin-resistant S. aureus (ORSA. The objective of this study was to determine the in vitro antimicrobial activity of arbekacin against 454 clinical isolates of ORSA. The isolates were consecutively collected between January and July, 2000, from patients hospitalized in 8 Brazilian medical centers. The antimicrobial susceptibility testing was performed by disk diffusion method according to NCCLS recommendations. The vast majority of the isolates, 453 strains (99.8%, were considered susceptible to arbekacin based on the criteria proposed by the Requirements for Antibiotic Products of Japan. Only 1 isolate (0.2% was classified as resistant. On the other hand, high rates of resistance were demonstrated for other aminoglycosides, such as gentamicin (97.6% resistance and amikacin (97.0% resistance. Resistance rate was also high for ciprofloxacin (98.0%. All isolates were considered susceptible to vancomycin. The excellent in vitro antimicrobial activity of arbekacin demonstrated in this study indicates that this antimicrobial agent may play an important role in the treatment of severe ORSA infections, especially those that show poor clinical response with vancomycin monotherapy. Since the aminoglycosides should not be used as monotherapy to treat Gram positive infections, further studies evaluating in vitro and in vivo synergistic activity of arbekacin combinations are necessary to clarify the clinical role of this aminoglycoside.

  17. In vitro antimicrobial activity of the aminoglycoside arbekacin tested against oxacillin-resistant Staphylococcus aureus isolated in Brazilian hospitals

    Directory of Open Access Journals (Sweden)

    Cordeiro Julio C. R.

    2001-01-01

    Full Text Available Arbekacin is an aminoglycoside used in Japan for treating infections caused by gentamicin and oxacillin-resistant S. aureus (ORSA. The objective of this study was to determine the in vitro antimicrobial activity of arbekacin against 454 clinical isolates of ORSA. The isolates were consecutively collected between January and July, 2000, from patients hospitalized in 8 Brazilian medical centers. The antimicrobial susceptibility testing was performed by disk diffusion method according to NCCLS recommendations. The vast majority of the isolates, 453 strains (99.8%, were considered susceptible to arbekacin based on the criteria proposed by the Requirements for Antibiotic Products of Japan. Only 1 isolate (0.2% was classified as resistant. On the other hand, high rates of resistance were demonstrated for other aminoglycosides, such as gentamicin (97.6% resistance and amikacin (97.0% resistance. Resistance rate was also high for ciprofloxacin (98.0%. All isolates were considered susceptible to vancomycin. The excellent in vitro antimicrobial activity of arbekacin demonstrated in this study indicates that this antimicrobial agent may play an important role in the treatment of severe ORSA infections, especially those that show poor clinical response with vancomycin monotherapy. Since the aminoglycosides should not be used as monotherapy to treat Gram positive infections, further studies evaluating in vitro and in vivo synergistic activity of arbekacin combinations are necessary to clarify the clinical role of this aminoglycoside.

  18. 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

  19. Chaperonin GroEL/GroES over-expression promotes multi-drug resistance in E. coli following exposure to aminoglycoside antibiotics

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    Lise eGoltermann

    2016-01-01

    Full Text Available Antibiotic resistance is an increasing challenge to modern healthcare. Aminoglycoside antiobiotics cause translation corruption and protein misfolding and aggregation in Escherichia coli. We previously showed that chaperonin GroEL/GroES depletion and overexpression sensitize and promote short-term tolerance, respectively, to this drug class. Here we show that chaperonin GroEL/GroES over-expression accelerates acquisition of aminoglycoside resistance and multi-drug resistance following sub-lethal aminoglycoside antibiotic exposure. Chaperonin buffering could provide a novel mechanism for antibiotic resistance and multi-drug resistance development.

  20. Study of the Interference between Plectranthus Species Essential Oils from Brazil and Aminoglycosides.

    Science.gov (United States)

    Galvão Rodrigues, Fabíola Fernandes; Costa, José Galberto Martins; Rodrigues, Fábio Fernandes Galvao; Campos, Adriana Rolim

    2013-01-01

    Plectranthus is one of the most representative genera of Lamiaceae family. In this study, the essential oils from Plectranthus amboinicus, Plectranthus ornatus, and Plectranthus barbatus were investigated for their chemical composition and antimicrobial and modulatory activities. The major components found were carvacrol (54.4%-P. amboinicus) and eugenol (22.9%-P. ornatus e 25.1%-P. barbatus). In vitro antimicrobial activity was conducted against Escherichia coli, Proteus vulgaris, Bacillus cereus, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus aureus (multiresistant) using microdilution method. The results of bioassay showed that all strains were sensitive to the oils, except P. aeruginosa that was resistant to P. amboinicus and P. ornatus. A synergistic effect of all essential oils combined with the aminoglycosides was demonstrated. These results show that P. amboinicus, P. ornatus, and P. barbatus inhibit the growth of pathogenic microorganism, and besides this they present antibiotic modifying activity, providing a new perspective against the problem of bacterial resistance to antibiotics.

  1. Parallel pathways in the biosynthesis of aminoglycoside antibiotics [version 1; referees: 2 approved

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    Yi Yu

    2017-05-01

    Full Text Available Despite their inherent toxicity and the global spread of bacterial resistance, aminoglycosides (AGs, an old class of microbial drugs, remain a valuable component of the antibiotic arsenal. Recent studies have continued to reveal the fascinating biochemistry of AG biosynthesis and the rich potential in their pathway engineering. In particular, parallel pathways have been shown to be common and widespread in AG biosynthesis, highlighting nature’s ingenuity in accessing diverse natural products from a limited set of genes. In this review, we discuss the parallel biosynthetic pathways of three representative AG antibiotics—kanamycin, gentamicin, and apramycin—as well as future directions towards the discovery and development of novel AGs.

  2. Distribution of genes encoding aminoglycoside-modifying enzymes among clinical isolates of methicillin-resistant staphylococci.

    Science.gov (United States)

    Perumal, N; Murugesan, S; Krishnan, P

    2016-01-01

    The objective of this study was to determine the distribution of genes encoding aminoglycoside-modifying enzymes (AMEs) and staphylococcal cassette chromosome mec (SCCmec) elements among clinical isolates of methicillin-resistant staphylococci (MRS). Antibiotic susceptibility test was done using Kirby-Bauer disk diffusion method. The presence of SCCmec types and AME genes, namely, aac (6')-Ie-aph (2''), aph (3')-IIIa and ant (4')-Ia was determined using two different multiplex polymerase chain reaction. The most encountered AME genes were aac (6')-Ie-aph (2'') (55.4%) followed by aph (3')-IIIa (32.3%) and ant (4')-Ia gene (9%). SCCmec type I (34%) was predominant in this study. In conclusion, the aac (6')-Ie-aph (2'') was the most common AME gene and SCCmec type I was most predominant among the MRS isolates.

  3. 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

  4. In vitro susceptibility pattern of acinetobacter species to commonly used cephalosporins, quinolones, and aminoglycosides

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    Prashanth K

    2004-01-01

    Full Text Available PURPOSE: Acinetobacter spp. is an emerging important nosocomial pathogen. Clinical isolates of this genus are often resistant to many antibiotics. The in vitro susceptibility of Acinetobacter isolates obtained from patients were tested for currently used antibiotics. In addition, the study aimed at biotyping of Acinetobacter baumannii. METHODS: A total of 66 isolates were phenotypically characterised through a large panel of 25 carbon assimilation tests and susceptibility through disc diffusion method with 10 antimicrobial agents were tested. MICs were determined only for second line broad-spectrum drugs such as cefotaxime, ceftazidime, amikacin, ciprofloxacin, and ofloxacin using NCCLS guidelines. RESULTS: Multiple drug resistance (MDR was only witnessed in A. baumannii and not in other Acinetobacter species. Aminoglycosides such as amikacin, netilmicin were most active against the MDR isolates tested (60% susceptibility. Ceftazidime was more active than cefotaxime. MDR A. baumannii strains were susceptible only to amikacin, netilmicin and ceftadizime. Ciprofloxacin had poor activity irrespective of isolates belonging to different DNA groups tested (58% resistance overall, 79% among A. baumannii. Strains of Biotypes 6 and 19 of A. baumannii showed broader resistance than those of biotype 10 and others. CONCLUSIONS: Strains of A. baumannii from patients in our hospital, were generally more resistant to quinolones, -lactam antibiotics, first and second generation cephalosporins and partially resistant to third generation cephalosporins and aminoglycosides. The strains belonging to other DNA groups of Acinetobacter were comparatively less resistant than A.baumannii, except ciprofloxacin. This study suggests that, a combination therapy, using a third generation cephalosporin and amikacin, would be best choice for treating Acinetobacter infections.

  5. Origin in Acinetobacter gyllenbergii and dissemination of aminoglycoside-modifying enzyme AAC(6')-Ih.

    Science.gov (United States)

    Yoon, Eun-Jeong; Goussard, Sylvie; Nemec, Alexandr; Lambert, Thierry; Courvalin, Patrice; Grillot-Courvalin, Catherine

    2016-03-01

    The aac(6')-Ih gene encoding aminoglycoside 6'-N-acetyltransferase type I subtype h [AAC(6')-Ih] is plasmid-borne in Acinetobacter baumannii where it confers high-level amikacin resistance, but its origin remains unknown. We searched for the gene in the genomes of a collection of 133 Acinetobacter spp. and studied its species specificity, expression and dissemination. Gene copy number was determined by quantitative PCR, expression by quantitative RT-PCR, MIC by microdilution and transfer by plasmid mobilization. The aac(6')-Ih gene was present in the chromosome of the two Acinetobacter gyllenbergii of the collection and was detected in all seven A. gyllenbergii clinical isolates. They had indistinguishable flanking regions indicating that the gene was intrinsic to this species. A. baumannii PIS Aba23 promoters were provided by insertion of ISAba23, which disrupted the Pnative promoter in A. gyllenbergii. Both types of promoters were similarly potent in Escherichia coli and A. baumannii. Aminoglycoside MICs for A. baumannii harbouring pIP1858 were higher than for A. gyllenbergii due to gene dosage. The non-self-transferable plasmid could be mobilized to other A. baumannii cells by the broad host range plasmid RP4. We have found the origin of aac(6')-Ih in A. gyllenbergii, a species isolated, although rarely, in humans, and documented that dissemination of this gene is restricted to the Acinetobacter genus. © 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.

  6. 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.

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

    Science.gov (United States)

    Christensen, Ellen G.; Gram, Lone; Kastbjerg, Vicky G.

    2011-01-01

    The human food-borne pathogen Listeria monocytogenes is capable of persisting in food processing plants despite cleaning and sanitation and is likely exposed to sublethal biocide concentrations. This could potentially affect susceptibility of the bacterium to biocides and other antimicrobial agents. The purpose of the present study was to determine if sublethal biocide concentrations affected antibiotic susceptibility in L. monocytogenes. Exposure of L. monocytogenes strains EGD and N53-1 to sublethal concentrations of Incimaxx DES (containing peroxy acids and hydrogen peroxide) and Triquart Super (containing quaternary ammonium compound) in four consecutive cultures did not alter the frequency of antibiotic-tolerant isolates, as determined by plating on 2× 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. However, all eight strains became resistant to gentamicin (up to 16-fold increase in MIC) after exposure to sublethal triclosan concentrations. Gentamicin-resistant isolates of strains N53-1 and 4446 were also resistant to other aminoglycosides, such as kanamycin, streptomycin, and tobramycin. Gentamicin 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 is commonly used in listeriosis treatment. The triclosan-induced resistance is, hence, of great concern. Further investigations are needed to determine the molecular mechanisms underlying the effect of triclosan. PMID:21746948

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

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    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.

  9. Ligand promiscuity through the eyes of the aminoglycoside N3 acetyltransferase IIa.

    Science.gov (United States)

    Norris, Adrianne L; Serpersu, Engin H

    2013-07-01

    Aminoglycoside-modifying enzymes (AGMEs) are expressed in many pathogenic bacteria and cause resistance to aminoglycoside (AG) antibiotics. Remarkably, the substrate promiscuity of AGMEs is quite variable. The molecular basis for such ligand promiscuity is largely unknown as there is not an obvious link between amino acid sequence or structure and the antibiotic profiles of AGMEs. To address this issue, this article presents the first kinetic and thermodynamic characterization of one of the least promiscuous AGMEs, the AG N3 acetyltransferase-IIa (AAC-IIa) and its comparison to two highly promiscuous AGMEs, the AG N3-acetyltransferase-IIIb (AAC-IIIb) and the AG phosphotransferase(3')-IIIa (APH). Despite having similar antibiotic selectivities, AAC-IIIb and APH catalyze different reactions and share no homology to one another. AAC-IIa and AAC-IIIb catalyze the same reaction and are very similar in both amino acid sequence and structure. However, they demonstrate strong differences in their substrate profiles and kinetic and thermodynamic properties. AAC-IIa and APH are also polar opposites in terms of ligand promiscuity but share no sequence or apparent structural homology. However, they both are highly dynamic and may even contain disordered segments and both adopt well-defined conformations when AGs are bound. Contrary to this AAC-IIIb maintains a well-defined structure even in apo form. Data presented herein suggest that the antibiotic promiscuity of AGMEs may be determined neither by the flexibility of the protein nor the size of the active site cavity alone but strongly modulated or controlled by the effects of the cosubstrate on the dynamic and thermodynamic properties of the enzyme. Copyright Copyright © 2013 The Protein Society.

  10. Effects of the aminoglycoside antibiotics, streptomycin and neomycin, on neuromuscular transmission. I. Presynaptic considerations.

    Science.gov (United States)

    Fiekers, J F

    1983-06-01

    The effects of two aminoglycoside antibiotics, streptomycin and neomycin, were studied in voltage-clamped transected twitch fibers of the costocutaneous muscles of garter snakes (species Thamnophis). The concentration-dependent effects of each antibiotic were quantitated by measuring miniature end-plate currents (mepcs) and evoked end-plate currents (epcs) in a single fiber before and in the presence of a wide range of concentrations of each antibiotic. The amplitude and the kinetics of these currents were studied and estimates of the quantal content of evoked transmitter release determined by the direct method of mean ratios, epc/mepc. A distinct separation was obtained between the concentrations of each antibiotic which demonstrated either pre- or postsynaptic actions. Both streptomycin and neomycin produced a concentration-dependent reduction in epc amplitude at concentrations which did not reduce mepc amplitude. Thus, the primary site of action for these antibiotics was considered of presynaptic origin. Streptomycin was approximately one-tenth as active as neomycin in reducing quantal release of acetylcholine. The marked depression in epc amplitude and quantal content produced by high concentrations of each antibiotic were reversed by elevating the external calcium concentration. Double logarithmic plots of the relationship between external calcium concentration and epc amplitude yielded a slope of approximately 3.8 in control physiological solution. In the presence of blocking concentrations of each antibiotic, increasing the external calcium concentration caused a parallel shift to the right of this relationship. These results suggest that the major mechanism for the neuromuscular depression produced by these aminoglycoside antibiotics is a competitive antagonism with calcium for a common presynaptic site required for evoked transmitter release.

  11. 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.

  12. Occurrence of aminoglycoside-modifying enzymes genes (aac(6')-I and ant(2″)-I) in clinical isolates of Pseudomonas aeruginosa from Southwest Nigeria.

    Science.gov (United States)

    Odumosu, Bamidele Tolulope; Adeniyi, Bolanle A; Chandra, Ram

    2015-12-01

    Enzymatic modification of aminoglycosides is the primary mechanism of resistance by Pseudomonas aeruginosa. We investigated the occurrence and mechanism of aminoglycosides resistance in P. aeruginosa isolates from hospitals in SouthWest Nigeria. A total of 54 consecutive, non-duplicate clinical isolates of P. aeruginosa were studied for the presence of aminoglycosides -modifying enzymes (AMEs) by PCR amplification and sequencing of genes encoding AMEs. Two types of AME genes [aac (6') - I and ant (2″) - I] were found in 12 isolates out of 54. Seven strains harboured one or more types of enzymes of which aac (6') - I was the most frequently found gene (10/54 isolates, 18.5%). None of the isolates investigated in this study were positive for aph, aac (3) and aac (6″) - II genes. Prevalence of P. aeruginosa producing AME genes in this study may suggest aminoglycosides use in Nigeria. This study highlights need for functional antimicrobial surveillance system in Nigeria.

  13. Ribosomal Protein S12 and Aminoglycoside Antibiotics Modulate A-site mRNA Cleavage and Transfer-Messenger RNA Activity in Escherichia coli*

    OpenAIRE

    Holberger, Laura E.; Hayes, Christopher S.

    2009-01-01

    Translational pausing in Escherichia coli can lead to mRNA cleavage within the ribosomal A-site. A-site mRNA cleavage is thought to facilitate transfer-messenger RNA (tmRNA)·SmpB- mediated recycling of stalled ribosome complexes. Here, we demonstrate that the aminoglycosides paromomycin and streptomycin inhibit A-site cleavage of stop codons during inefficient translation termination. Aminoglycosides also induced stop codon read-through, suggesting that these antibiotics alleviate ribosome pa...

  14. Real-time examination of aminoglycoside activity towards bacterial mimetic membranes using Quartz Crystal Microbalance with Dissipation monitoring (QCM-D).

    Science.gov (United States)

    Joshi, Tanmaya; Voo, Zhi Xiang; Graham, Bim; Spiccia, Leone; Martin, Lisandra L

    2015-02-01

    The rapid increase in multi-drug resistant bacteria has resulted in previously discontinued treatments being revisited. Aminoglycosides are effective "old" antibacterial agents that fall within this category. Despite extensive usage and understanding of their intracellular targets, there is limited mechanistic knowledge regarding how aminoglycosides penetrate bacterial membranes. Thus, the activity of two well-known aminoglycosides, kanamycin A and neomycin B, towards a bacterial mimetic membrane (DMPC:DMPG (4:1)) was examined using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D). The macroscopic effect of increasing the aminoglycoside concentration showed that kanamycin A exerts a threshold response, switching from binding to the membrane to disruption of the surface. Neomycin B, however, disrupted the membrane at all concentrations examined. At concentrations above the threshold value observed for kanamycin A, both aminoglycosides revealed similar mechanistic details. That is, they both inserted into the bacterial mimetic lipid bilayer, prior to disruption via loss of materials, presumably aminoglycoside-membrane composites. Depth profile analysis of this membrane interaction was achieved using the overtones of the quartz crystal sensor. The measured data is consistent with a two-stage process in which insertion of the aminoglycoside precedes the 'detergent-like' removal of membranes from the sensor. The results of this study contribute to the insight required for aminoglycosides to be reconsidered as active antimicrobial agents/co-agents by providing details of activity at the bacterial membrane. Kanamycin and neomycin still offer potential as antimicrobial therapeutics for the future and the QCM-D method illustrates great promise for screening new antibacterial or antiviral drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. 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.

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

    Science.gov (United States)

    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

  17. Determination of 14 aminoglycosides by LC-MS/MS using molecularly imprinted polymer solid phase extraction for clean-up.

    Science.gov (United States)

    Savoy, Marie-Claude; Woo, Pei Mun; Ulrich, Pauline; Tarres, Adrienne; Mottier, Pascal; Desmarchelier, Aurélien

    2018-04-01

    An LC-MS/MS method for screening 14 aminoglycosides in foodstuffs of animal origin is presented. Its scope includes raw materials and processed ingredients but also finished products composed of milk, meat, fish, egg or fat. Aminoglycosides are extracted in an acidic aqueous solution, which is first recovered after centrifugation, then diluted with a basic buffer and finally purified by molecularly imprinted polymer-solid phase extraction (MIP-SPE). Analytes are detected within 8 min by ion-pair reversed phase LC-MS/MS. Due to the large range of foodstuffs involved, the variability of matrix effects led to significant MS signal variations. This was circumvented by systematically extracting each sample twice, i.e. 'unspiked' and 'spiked' at the screening target concentration of 50 µg kg -1 . The method was validated according to the European Community Reference Laboratories Residues Guidelines giving false-negative and false-positive rates ≤3% for all compounds. Ruggedness of the method was further demonstrated in quality control operations by a second laboratory. The 14 aminoglycosides in water-based standard solutions were stable for up to 6 months when stored at either -80°C, -20°C or at 4°C storage temperatures.

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

    Directory of Open Access Journals (Sweden)

    Edward eCunningham-Oakes

    2015-10-01

    Full Text Available Infections caused by methicillin-sensitive (MSSA and methicillin-resistant Staphylococcus 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.

  19. Increased prevalence of aminoglycoside resistance in clinical isolates of Escherichia coli and Klebsiella spp. in Norway is associated with the acquisition of AAC(3)-II and AAC(6')-Ib.

    Science.gov (United States)

    Haldorsen, Bjørg C; Simonsen, Gunnar Skov; Sundsfjord, Arnfinn; Samuelsen, Orjan

    2014-01-01

    In this study, we show that the increasing prevalence of aminoglycoside resistance observed in Norway among clinical Escherichia coli and Klebsiella spp. isolates is mainly due to the presence of the aminoglycoside-modifying enzymes AAC(3)-II and AAC(6')-Ib. A frequent co-association of aminoglycoside resistance with Cefotaximase-München group 1 extended-spectrum β-lactamases was also observed. © 2013.

  20. Study of the Interference between Plectranthus Species Essential Oils from Brazil and Aminoglycosides

    Directory of Open Access Journals (Sweden)

    Fabíola Fernandes Galvão Rodrigues

    2013-01-01

    Full Text Available Plectranthus is one of the most representative genera of Lamiaceae family. In this study, the essential oils from Plectranthus amboinicus, Plectranthus ornatus, and Plectranthus barbatus were investigated for their chemical composition and antimicrobial and modulatory activities. The major components found were carvacrol (54.4%—P. amboinicus and eugenol (22.9%—P. ornatus e 25.1%—P. barbatus. In vitro antimicrobial activity was conducted against Escherichia coli, Proteus vulgaris, Bacillus cereus, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus aureus (multiresistant using microdilution method. The results of bioassay showed that all strains were sensitive to the oils, except P. aeruginosa that was resistant to P. amboinicus and P. ornatus. A synergistic effect of all essential oils combined with the aminoglycosides was demonstrated. These results show that P. amboinicus, P. ornatus, and P. barbatus inhibit the growth of pathogenic microorganism, and besides this they present antibiotic modifying activity, providing a new perspective against the problem of bacterial resistance to antibiotics.

  1. 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.

  2. 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.

  3. 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.

  4. 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. .

  5. Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

    International Nuclear Information System (INIS)

    Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J.

    2012-01-01

    A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH 4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

  6. Aminoglycoside resistance mechanisms in Pseudomonas aeruginosa isolates from non-cystic fibrosis patients in Thailand.

    Science.gov (United States)

    Poonsuk, Kanchana; Tribuddharat, Chanwit; Chuanchuen, Rungtip

    2013-01-01

    This study aimed to examine aminoglycosides (AMGs) resistance mechanisms, including the AMG-modifying enzyme genes, mexXY, rplY, nuoG, and galU, in the Pseudomonas aeruginosa non-cystic fibrosis (CF) isolates in Thailand. One hundred P. aeruginosa isolates from non-CF patients were examined for susceptibility to AMGs and for the presence of 10 AMG-modifying enzyme genes. Thirty randomly selected isolates were tested for transcription of mexXY and nuoG and mutations in rplY and galU. All the P. aeruginosa isolates exhibited simultaneous resistance to at least 4 AMGs. High resistance rates to amikacin (92%), gentamicin (95%), streptomycin (99%), and tobramycin (96%) were observed, and all isolates were resistant to kanamycin, neomycin, and spectinomycin. Nine AMG-modifying enzyme genes were detected, including aadA1 (84%), aadB (84%), aadA2 (67%), ant(2″)-Ia (72%), strA-strB (70%), aph(3')-IIb (57%), aac(3')-Ia (40%), and aac(6')-IIa (27%). None of the isolates harbored aac(6')-IIb. Of 30 isolates tested, all but 1 isolate expressed MexXY. Two isolates did not express nuoG. Six isolates carried an amino acid change in RplY, but none of the isolates harbored mutation in galU. The results indicated that the AMG-modifying enzyme genes were widespread among the P. aeruginosa non-CF isolates. The MexXY efflux pump and inactivation for rplY played a role in AMG resistance but disruption of nuoG or galU did not.

  7. Integrity and regeneration of mechanotransduction machinery regulate aminoglycoside entry and sensory cell death.

    Directory of Open Access Journals (Sweden)

    Andrew A Vu

    Full Text Available Sound perception requires functional hair cell mechanotransduction (MET machinery, including the MET channels and tip-link proteins. Prior work showed that uptake of ototoxic aminoglycosides (AG into hair cells requires functional MET channels. In this study, we examined whether tip-link proteins, including Cadherin 23 (Cdh23, regulate AG entry into hair cells. Using time-lapse microscopy on cochlear explants, we found rapid uptake of gentamicin-conjugated Texas Red (GTTR into hair cells from three-day-old Cdh23(+/+ and Cdh23(v2J/+ mice, but failed to detect GTTR uptake in Cdh23(v2J/v2J hair cells. Pre-treatment of wildtype cochleae with the calcium chelator 1,2-bis(o-aminophenoxy ethane-N,N,N',N'-tetraacetic acid (BAPTA to disrupt tip-links also effectively reduced GTTR uptake into hair cells. Both Cdh23(v2J/v2J and BAPTA-treated hair cells were protected from degeneration caused by gentamicin. Six hours after BAPTA treatment, GTTR uptake remained reduced in comparison to controls; by 24 hours, drug uptake was comparable between untreated and BAPTA-treated hair cells, which again became susceptible to cell death induced by gentamicin. Together, these results provide genetic and pharmacologic evidence that tip-links are required for AG uptake and toxicity in hair cells. Because tip-links can spontaneously regenerate, their temporary breakage offers a limited time window when hair cells are protected from AG toxicity.

  8. Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J., E-mail: aruncccm@gmail.com

    2012-08-01

    A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV-visible spectroscopy, transmission electron microscopy, X-ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 {+-} 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected-area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: Black-Right-Pointing-Pointer Method for NaBH{sub 4} reduced and BSA capped gold nanoparticle was standardized. Black-Right-Pointing-Pointer Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. Black-Right-Pointing-Pointer Nanoparticles are extremely stable towards pH modification and electrolyte addition. Black

  9. Aminoglycoside exposure and renal function before lung transplantation in adult cystic fibrosis patients.

    Science.gov (United States)

    Novel-Catin, Etienne; Pelletier, Solenne; Reynaud, Quitterie; Nove-Josserand, Raphaele; Durupt, Stephane; Dubourg, Laurence; Durieu, Isabelle; Fouque, Denis

    2018-04-18

    Patients with cystic fibrosis (CF) are at risk of kidney injury even before undergoing lung transplantation, because of prolonged exposure to aminoglycosides (AGs), chronic dehydration and complications of diabetes mellitus. The usual equations estimating the glomerular filtration rate (GFR), such as Cockcroft-Gault and Modification of Diet in Renal Disease, are not adapted to the CF population due to patients' low body weight and reduced muscle mass. The aim of this study was to precisely measure GFR in adult CF patients and to see whether repeated AG treatment would impair renal function before lung transplantation. Inulin or iohexol clearances were performed in 25 adult CF patients when they entered the lung transplant waiting list. No patient was treated with AGs at the time of GFR measurement. Body mass index (BMI), history of diabetes mellitus and blood pressure were recorded. Exposure to intravenous (IV) AGs within 5 years prior to the GFR measurement was obtained from the patient's medical files. Urine samples were collected to check for albuminuria and proteinuria. The population was predominantly female (67%). The mean age was 32 years, the mean BMI was 19 kg/m2 and 28% had CF-related diabetes. Median exposure to IV AG within 5 years before GFR measurement was 155 days with a mean dosage of 7.7mg/kg/day. The mean measured GFR was 106 mL/min/1.73 m2 and the mean estimated GFR according to the Chronic Kidney Disease Epidemiology Collaboration formula was 124 mL/min/1.73 m2. Despite prolonged exposure to high-dose IV AG, no decline in GFR was observed in these patients.

  10. 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

  11. 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.

  12. 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

  13. 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...

  14. 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.

  15. A new subclass of intrinsic aminoglycoside nucleotidyltransferases, ANT(3")-II, is horizontally transferred among Acinetobacter spp. by homologous recombination

    Science.gov (United States)

    Zhang, Gang; Leclercq, Sébastien Olivier; Tian, Jingjing; Wang, Chao; Ai, Guomin; Liu, Shuangjiang

    2017-01-01

    The emergence and spread of antibiotic resistance among Acinetobacter spp. have been investigated extensively. Most studies focused on the multiple antibiotic resistance genes located on plasmids or genomic resistance islands. On the other hand, the mechanisms controlling intrinsic resistance are still not well understood. In this study, we identified the novel subclass of aminoglycoside nucleotidyltransferase ANT(3")-II in Acinetobacter spp., which comprised numerous variants distributed among three main clades. All members of this subclass can inactivate streptomycin and spectinomycin. The three ant(3")-II genes, encoding for the three ANT(3")-II clades, are widely distributed in the genus Acinetobacter and always located in the same conserved genomic region. According to their prevalence, these genes are intrinsic in Acinetobacter baumannii, Acinetobacter pittii, and Acinetobacter gyllenbergii. We also demonstrated that the ant(3")-II genes are located in a homologous recombination hotspot and were recurrently transferred among Acinetobacter species. In conclusion, our findings demonstrated a novel mechanism of natural resistance in Acinetobacter spp., identified a novel subclass of aminoglycoside nucleotidyltransferase and provided new insight into the evolutionary history of intrinsic resistance genes. PMID:28152054

  16. 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.

  17. Complex pollution of antibiotic resistance genes due to beta-lactam and aminoglycoside use in aquaculture farming.

    Science.gov (United States)

    Chen, Baowei; Lin, Lan; Fang, Ling; Yang, Ying; Chen, Enzhong; Yuan, Ke; Zou, Shichun; Wang, Xiaowei; Luan, Tiangang

    2018-05-01

    The prevalence of antibiotic resistance in the modern world has raised global concerns for public health. Establishing relationships between antibiotic use and antibiotic resistance genes (ARGs) is essential to understanding the dissemination and accumulation of ARGs in a human-impacted environment. In this study, ARG profiles in the sediments from a bullfrog farm, where penicillin and amoxicillin (beta-lactams) and gentamicin (aminoglycoside) were used for prophylactic purposes, were analyzed using metagenomic approaches. Analysis of both extracellular and intracellular DNA (eDNA and iDNA) demonstrated that use of the above-mentioned antibiotics led to complex pollution of ARGs not only related to beta-lactams and aminoglycoside but also to sulfonamides, tetracyclines, and macrolides. Most of the ARGs in the sediments from the bullfrog farm were likely carried by plasmids. A significant correlation was observed between the total abundance of ARG-related plasmids and that of plasmid-carrying ARGs. Approximately 85% of the plasmids likely present in the sediment from the bullfrog farm possessed at least 3 ARG subtypes, which conferred the resistance of bacterial hosts to different antibiotic categories. Our results suggest that antibiotics could lead to complex pollution of ARGs unrelated to those administered due to the concurrence of ARGs in the plasmids. Copyright © 2018. Published by Elsevier Ltd.

  18. 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.

  19. d-Tubocurarine and Berbamine: Alkaloids That Are Permeant Blockers of the Hair Cell's Mechano-Electrical Transducer Channel and Protect from Aminoglycoside Toxicity

    NARCIS (Netherlands)

    Kirkwood, Nerissa K.; Derudas, Marco; Kenyon, Emma J; Huckvale, Rosemary; van Netten, Sietse; Ward, Simon; Richardson, Guy P; Kros, Corne J

    2017-01-01

    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

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

    Science.gov (United States)

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

    2014-01-01

    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. PMID:24489121

  1. 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

  2. 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

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

    Science.gov (United States)

    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.

  4. 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.

  5. MexXY efflux pump overexpression and aminoglycoside resistance in cystic fibrosis isolates of Pseudomonas aeruginosa from chronic infections.

    Science.gov (United States)

    Singh, Manu; Yau, Yvonne C W; Wang, Shirley; Waters, Valerie; Kumar, Ayush

    2017-12-01

    In this study, we analyzed 15 multidrug-resistant cystic fibrosis isolates of Pseudomonas aeruginosa from chronic lung infections for expression of 4 different multidrug efflux systems (MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY), using quantitative reverse transcriptase PCR. Overexpression of MexXY pump was observed in all of the isolates tested. Analysis of regulatory genes that control the expression of these 4 efflux pumps revealed a number of previously uncharacterized mutations. Our work shows that MexXY pump overexpression is common in cystic fibrosis isolates and could be contributing to their reduced aminoglycoside susceptibility. Further, we also identified novel mutations in the regulatory genes of the 4 abovementioned Resistance-Nodulation-Division superfamily pumps that may be involved in the overexpression of these pumps.

  6. Involvement of aph(3‘-IIa in the formation of mosaic aminoglycoside resistance genes in natural environments

    Directory of Open Access Journals (Sweden)

    Markus eWoegerbauer

    2015-05-01

    Full Text Available Intragenic recombination leading to mosaic gene formation is known to alter resistance profiles for particular genes and bacterial species. Few studies have examined to what extent aminoglycoside resistance genes undergo intragenic recombination.We screened the GenBank database for mosaic gene formation in homologs of the aph(3’-IIa (nptII gene. APH(3’-IIa inactivates important aminoglycoside antibiotics. The gene is widely used as a selectable marker in biotechnology and enters the environment via laboratory discharges and the release of transgenic organisms. Such releases may provide opportunities for recombination in competent environmental bacteria.The retrieved GenBank sequences were grouped in 3 datasets comprising river water samples, duck pathogens and full-length variants from various bacterial genomes and plasmids. Analysis for recombination in these datasets was performed with the Recombination Detection Program, RDP4, and the Genetic Algorithm for Recombination Detection, GARD.From a total of 89 homologous sequences, 83% showed 99% - 100% sequence identity with aph(3’-IIa originally described as part of transposon Tn5. Fifty one were unique sequence variants eligible for recombination analysis. Only a single recombination event was identified with high confidence and indicated the involvement of aph(3’-IIa in the formation of a mosaic gene located on a plasmid of environmental origin in the multi-resistant isolate Pseudomonas aeruginosa PA96. The available data suggest that aph(3’-IIa is not an archetypical mosaic gene as the divergence between the described sequence variants and the number of detectable recombination events is low. This is in contrast to the numerous mosaic alleles reported for certain penicillin or tetracycline resistance determinants.

  7. Prevalence of plasmid-mediated quinolone resistance and aminoglycoside resistance determinants among carbapeneme non-susceptible Enterobacter cloacae.

    Directory of Open Access Journals (Sweden)

    Shifeng Huang

    Full Text Available BACKGROUND: Simultaneous resistance to aminoglycosides and fluoroquinolones in carbapeneme non-susceptible (CNS isolates will inevitably create problems. The present study was performed to characterize the prevalence of the plasmid-mediated quinolone resistance determinants (QRDs and aminoglycoside resistance determinants (ARDs among the CNS Enterobacter cloacae (E. cloacae isolates in a Chinese teaching hospital, and to acquire their molecular epidemiological characteristics. METHODS: The β-lactamases genes (including class A carbapenemase genes bla(KPC and bla(SME, metallo-β-lactamase genes (MBLs bla(IMP, bla(VIM and bla(NDM, and extended spectrum β-lactamases (ESBLs,bla(CTX-M, bla(TEM and bla(SHV, QRDs (including qnrA, qnrB, qnrS and aac(6'-Ib-cr and ARDs (including aac(6'-Ib, armA and rmtB of these 35 isolates were determined by PCR and sequenced bidirectionally. The clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE. RESULTS: Of the 35 isolates, 9 (25.7% harbored a carbapenemase gene; 23 (65.7% carried ESBLs; 24 (68.6% were QRD positive; and 27 (77.1% were ARD positive. Among the 5 bla(IMP-8 positive strains, 4 (80% contained both ESBL and QRD genes, and all the 5 (100% harbored ARD genes. Of the 23 ESBLs positive isolates, 6 (26.1% were carbapenemase positive, 14 (60.9% were QRD positive, and 18 (78.3% were ARD positive. PFGE revealed genetic diversity among the 35 isolates, indicating that the high prevalence of CNS E. cloacae isolates was not caused by clonal dissemination. CONCLUSION: QRD and ARD genes were highly prevalent among the CNS E. cloacae isolates. Multiple resistant genes were co-expressed in the same isolates. The CNS E. cloacae isolate co-expressing bla(NDM-1, bla(IMP-26, qnrA1 and qnrS1 was first reported.

  8. 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.

  9. Impairing methylations at ribosome RNA, a point mutation-dependent strategy for aminoglycoside resistance: the rsmG case.

    Science.gov (United States)

    Benítez-Páez, Alfonso; Cárdenas-Brito, Sonia; Corredor, Mauricio; Villarroya, Magda; Armengod, María Eugenia

    2014-04-01

    Aminoglycosides like streptomycin are well-known for binding at specific regions of ribosome RNA and then acting as translation inhibitors. Nowadays, several pathogens have been detected to acquire an undefined strategy involving mutation at non structural ribosome genes like those acting as RNA methylases. rsmG is one of those genes which encodes an AdoMet-dependent methyltransferase responsible for the synthesis of m 7 G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding. Loss of the m 7 G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning. After taking into account genetic information indicating that some clinical isolates of human pathogens show streptomycin resistance associated with mutations at rsmG , we decided to explore new hot spots for mutation capable of impairing the RsmG in vivo function and of promoting low-level streptomycin resistance. To gain insights into the molecular and genetic mechanism of acquiring this aminoglycoside resistance phenotype and the emergence of high-level streptomycin resistance in rsmG mutants, we mutated Escherichia coli rsmG and also performed a genotyping study on rpsL from several isolates showing the ability to grow at higher streptomycin concentrations than parental strains. We found that the mutations at rpsL were preferentially present in these mutants, and we observed a clear synergy between rsmG and rpsL genes to induce streptomycin resistance. We contribute to understand a common mechanism that is probably transferable to other ribosome RNA methylase genes responsible for modifications at central sites for ribosome function.

  10. The major aminoglycoside-modifying enzyme AAC(3)-II found in Escherichia coli determines a significant disparity in its resistance to gentamicin and amikacin in China.

    Science.gov (United States)

    Xiao, Yonghong; Hu, Yunjian

    2012-02-01

    The aim of this study was to investigate the prevalence of aminoglycoside-modifying enzymes in Escherichia coli in different areas of China and to explore the relationship between pandemic enzyme type and bacterial resistance to antimicrobial agents in China. Gentamicin- or etimicin-resistant clinical isolates of E. coli were collected from different areas of China, and the in vitro antibacterial activity of 11 aminoglycoside agents was determined using standard (Clinical and Laboratory Standards Institute) agar dilution methods. Twelve aminoglycoside-modifying enzyme genes were detected by PCR and confirmed by DNA sequencing. A total of 205 E. coli strains were collected from nine hospitals in seven cities. All strains were highly resistant to gentamicin or etimicin, whereas resistance to tobramycin, netilmicin, and kanamycin was slightly lower. However, less than 15% of isolates were resistant to amikacin and isepamicin. Of the gentamicin-resistant strains, 88.2% and 86.7% were sensitive to isepamicin and amikacin, respectively. Five aminoglycoside-modifying enzyme genes were detected in 191 strains, whereas the remaining 14 strains were negative. The most common gene type was aac(3)-II (162 strains), followed by aac(6')-I (50 strains), ant(3″)-I (28 strains), aph(3')-II (20 strains), and ant(2″)-I (20 strains). Ninety-five strains yielded aac(3)-II only, whereas the others contained two or three genes. The three main gene combinations were aac(6')-I/aac(3)-II (28 strains), aac(3)-II/ant(3″)-I (11 strains), and aac(3)-II/aac(6')-I (10 strains). Regional bacterial resistance and enzyme distribution were roughly similar, although minor differences were found in Guangzhou, Jinan, and Dalian, which were the sources of most of the amikacin- or isepamicin-resistant strains. Chinese clinical isolates of E. coli remain highly resistant to gentamicin and etimicin, but are susceptible to amikacin and isepamicin. The dominant type of aminoglycoside-modifying enzyme

  11. Molecular identification of aminoglycoside-modifying enzymes in clinical isolates of Escherichia coli resistant to amoxicillin/clavulanic acid isolated in Spain.

    Science.gov (United States)

    Fernández-Martínez, Marta; Miró, Elisenda; Ortega, Adriana; Bou, Germán; González-López, Juan José; Oliver, Antonio; Pascual, Alvaro; Cercenado, Emilia; Oteo, Jesús; Martínez-Martínez, Luis; Navarro, Ferran

    2015-08-01

    The activity of eight aminoglycosides (amikacin, apramycin, arbekacin, gentamicin, kanamycin, neomycin, netilmicin and tobramycin) against a collection of 257 amoxicillin/clavulanic acid (AMC)-resistant Escherichia coli isolates was determined by microdilution. Aminoglycoside resistance rates, the prevalence of aminoglycoside-modifying enzyme (AME) genes, the relationship between AME gene detection and resistance phenotype to aminoglycosides, and the association of AME genes with mechanisms of AMC resistance in E. coli isolates in Spain were investigated. Aminoglycoside-resistant isolates were screened for the presence of genes encoding common AMEs [aac(3)-Ia, aac(3)-IIa, aac(3)-IVa, aac(6')-Ib, ant(2″)-Ia, ant(4')-IIa and aph(3')-Ia] or 16S rRNA methylases (armA, rmtB, rmtC and npmA). In total, 105 isolates (40.9%) were resistant to at least one of the aminoglycosides tested. Amikacin, apramycin and arbekacin showed better activity, with MIC90 values of 2mg/L (arbekacin) and 8mg/L (amikacin and apramycin). Kanamycin presented the highest MIC90 (128mg/L). The most common AME gene was aac(6')-Ib (36 strains; 34.3%), followed by aph(3')-Ia (31 strains; 29.5%), ant(2″)-Ia (29 strains; 27.6%) and aac(3)-IIa (23 strains; 21.9%). aac(3)-Ia, aac(3)-IVa, ant(4')-IIa and the four methylases were not detected. The ant(2″)-Ia gene was usually associated with OXA-1 [21/30; 70%], whilst 23/25 (92%) strains producing CTX-M-15 had the aac(6')-Ib gene. The most prevalent AME gene was aac(6')-Ib (18/41; 44%) in nosocomial isolates, whilst ant(2″)-Ia and aph(3')-Ia genes (20/64; 31%) were more frequent in strains of community origin. In 64.6% isolates the phenotypic profile correlated with the presence of commonly encountered AMEs. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  12. Looking for new preparations for antibacterial therapy. IV. New antimicrobial agents from the aminoglycoside, macrolide and tetracycline groups in clinical trials.

    Science.gov (United States)

    Karpiuk, Izabela; Tyski, Stefan

    2015-01-01

    This paper is the fourth in a series on the search for new antibacterial therapies, and covers new compounds belonging to the aminoglycoside, macrolide and tetracycline groups of antibiotics. The article describes eight new substances at the clinical trial stage of development. One of them is an aminoglycoside (plazomicin), four are macrolides, collectively known as ketolides (cethromycin, solithromycin, EDP-420 and EDP-788), and the remaining three are members of the tetracycline group (omadacycline, eravacycline, sarecycline). Despite the long-term and very expensive process of collecting documentation proving the efficacy of antimicrobial drugs, there is a possibility, that particular compounds find use as active ingredients of medicinal products allowing for the triumph over the clinically relevant, dangerous bacteria.

  13. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Dionisotti, S.; Bamonte, F.; Scaglione, F.; Ongini, E. (Research Lab., Schering-Plough S.P.A., Comazzo, Milan (Italy))

    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. Emergence of ArmA, a 16S rRNA methylase in highly aminoglycoside-resistant clinical isolates of Klebsiella pneumoniae and Klebsiella oxytoca in Okinawa, Japan.

    Science.gov (United States)

    Uechi, Kohei; Tada, Tatsuya; Shimada, Kayo; Nakasone, Isamu; Sonozaki, Tetsu; Kirikae, Teruo; Fujita, Jiro

    2018-01-01

    This study describes highly aminoglycoside-resistant Klebsiella pneumoniae and Klebsiella oxytoca clinical isolates obtained from an inpatient in Okinawa, Japan, with no known record of traveling overseas. The minimum inhibitory concentrations of amikacin and arbekacin against these strains were >1024 μg/ml. Whole-genome sequencing analysis revealed that these isolates harbored armA, which encodes a 16S rRNA methylase, ArmA, that confers pan-aminoglycoside resistance. This is the second report of K. pneumoniae harboring armA and the first report of K. oxytoca harboring a 16S rRNA methylase encoding gene in Japan. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  16. 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

  17. Increasing Prevalence of Aminoglycoside-Resistant Enterococcus faecalis Isolates Due to the aac(6')-aph(2") Gene: A Therapeutic Problem in Kermanshah, Iran.

    Science.gov (United States)

    Khani, Mitra; Fatollahzade, Mahdie; Pajavand, Hamid; Bakhtiari, Somaye; Abiri, Ramin

    2016-03-01

    Enterococci are important pathogens in nosocomial infections. Various types of antibiotics, such as aminoglycosides, are used for treatment of these infections. Enterococci can acquire resistant traits, which can lead to therapeutic problems with aminoglycosides. This study was designed to identify the prevalence of, and to compare, the aac(6')-aph(2") and aph(3)-IIIa genes and their antimicrobial resistance patterns among Enterococcus faecalis and E. faecium isolates from patients at Imam Reza hospital in Kermanshah in 2011 - 2012. One hundred thirty-eight clinical specimens collected from different wards of Imam Reza hospital were identified to the species level by biochemical tests. Antimicrobial susceptibility tests against kanamycin, teicoplanin, streptomycin, imipenem, ciprofloxacin, and ampicillin were performed by the disk diffusion method. The minimum inhibitory concentrations of gentamicin, streptomycin, kanamycin, and amikacin were evaluated with the microbroth dilution method. The aminoglycoside resistance genes aac(6')-aph(2") and aph(3")-IIIa were analyzed with multiplex PCR. The prevalence of isolates was 33 (24.1%) for E. faecium and 63 (46%) for E. faecalis. Eighty-nine percent of the isolates were high-level gentamicin resistant (HLGR), and 32.8% of E. faecium isolates and 67.2% of E. faecalis isolates carried aac(6')-aph(2"). The prevalence of aph(3")-IIIa among the E. faecalis and E. faecium isolates was 22.7% and 77.3%, respectively. Remarkably increased incidence of aac(6')-aph(2") among HLGR isolates explains the relationship between this gene and the high level of resistance to aminoglycosides. As the resistant gene among enterococci can be transferred, the use of new-generation antibiotics is necessary.

  18. 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...... and amikacin from an Indian hospital and we additionally screened for the novel RmtF enzyme in 132 UK isolates containing NDM....

  19. Identification of a small molecule inhibitor of the aminoglycoside 6'-N-acetyltransferase type ib [AAC(6')-ib] using mixture-based combinatorial libraries.

    Science.gov (United States)

    Tran, Tung; Chiem, Kevin; Jani, Saumya; Arivett, Brock A; Lin, David L; Lad, Rupali; Jimenez, Verónica; Farone, Mary B; Debevec, Ginamarie; Santos, Radleigh; Giulianotti, Marc; Pinilla, Clemencia; Tolmasky, Marcelo E

    2018-02-01

    The aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib] is the most widely distributed enzyme among AAC(6')-I-producing Gram-negative pathogens and confers resistance to clinically relevant aminoglycosides including amikacin. This enzyme is therefore ideal to target with enzymatic inhibitors that could overcome resistance to aminoglycosides. The search for inhibitors was carried out using mixture-based combinatorial libraries, the scaffold ranking approach, and the positional scanning strategy. A library with high inhibitory activity had pyrrolidine pentamine scaffold and was selected for further analysis. This library contained 738,192 compounds with functionalities derived from 26 different amino acids (R1, R2 and R3) and 42 different carboxylic acids (R4) in four R group functionalities. The most active compounds all contained S-phenyl (R1 and R3) and S-hydromethyl (R2) functionalities at three locations and differed at the R4 position. The compound containing 3-phenylbutyl at R4 (compound 206) was a robust enzymatic inhibitor in vitro, in combination with amikacin potentiated the inhibition of growth of three resistant bacteria in culture, and improved survival when used as treatment of Galleria mellonella infected with aac(6')-Ib-harboring Klebsiella pneumoniae and Acinetobacter baumannii strains. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  20. Purification, Crystallization And Preliminary X-Ray Analysis of Aminoglycoside-2 ''-Phosphotransferase-Ic [APH(2 '')-Ic] From Enterococcus Gallinarum

    Energy Technology Data Exchange (ETDEWEB)

    Byrnes, L.J.; /SLAC, SSRL; Badarau, A.; Vakulenko, S.B.; /Notre Dame U.; Smith, C.A.; /SLAC, SSRL

    2009-04-30

    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{double_prime}-phosphotransferase-Ic [APH(2{double_prime})-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{double_prime})-Ic variants were crystallized in the presence of 14-20%(w/v) PEG 4000, 0.25 M MgCl{sub 2}, 0.1 M Tris-HCl pH 8.5 and 1 mM Mg{sub 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 {angstrom}, {beta} = 108.8{sup o}. X-ray diffraction data were collected to approximately 2.15 {angstrom} resolution from an F108L crystal at beamline BL9-2 at SSRL, Stanford, California, USA.

  1. A two-component regulatory system interconnects resistance to polymyxins, aminoglycosides, fluoroquinolones, and β-lactams in Pseudomonas aeruginosa.

    Science.gov (United States)

    Muller, Cédric; Plésiat, Patrick; Jeannot, Katy

    2011-03-01

    Constitutive overexpression of the active efflux system MexXY/OprM is a major cause of resistance to aminoglycosides, fluoroquinolones, and cefepime in clinical strains of Pseudomonas aeruginosa. Upregulation of this pump often results from mutations occurring in mexZ, the local repressor gene of the mexXY operon. In this study, analysis of MexXY-overproducing mutants selected in vitro from reference strain PAO1Bes on amikacin (at a concentration 1.5-fold higher than the MIC) led to identification of a new class of mutants harboring an intact mexZ gene and exhibiting increased resistance to colistin and imipenem in addition to aminoglycosides, fluoroquinolones, and cefepime. Reverse transcription-quantitative PCR (RT-qPCR) experiments on a selected clone named PAOW2 demonstrated that mexXY overexpression was independent of mexZ and the PA5471 gene, which is required for drug-dependent induction of mexXY. Furthermore, the transcript levels of the oprD gene, which encodes the carbapenem-selective porin OprD, were found to be reduced drastically in PAOW2. Whole-genome sequencing revealed a single mutation resulting in an M59I substitution in the ParR protein, the response regulator of the ParRS two-component regulatory system (with ParS being the sensor kinase), which is required for adaptive resistance of P. aeruginosa to polycationic peptides such as colistin. The multidrug resistance phenotype was suppressed in PAOW2 by deletion of the parS and parRS genes and conferred to PAO1Bes by chromosomal insertion of the mutated parRS locus from PAOW2. As shown by transcriptomic analysis, only a very small number of genes were expressed differentially between PAOW2 and PAO1Bes, including the lipopolysaccharide (LPS) modification operon arnBCADTEF-ugd, responsible for resistance to polycationic agents. Exposure of wild-type PAO1Bes to different polycationic peptides, including colistin, was shown to result in increased mexY and repressed oprD expression via Par

  2. 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.

  3. tmRNA decreases the bactericidal activity of aminoglycosides and the susceptibility to inhibitors of cell wall synthesis.

    Science.gov (United States)

    Luidalepp, Hannes; Hallier, Marc; Felden, Brice; Tenson, Tanel

    2005-04-01

    Trans-translation is a process that recycles ribosomes stalled on problematic mRNAs. tmRNA, coded by the DeltassrA gene, is a major component of trans-translation. Bacteria lacking tmRNA are more sensitive to several inhibitors of protein synthesis when compared to a wild type strain. We measured bacterial growth of the DeltassrA and wild type strains in Escherichia coli in the presence of 14 antibiotics including some that do not target protein synthesis. Both the optical density of the bacterial cultures and the number of viable cells were monitored. For the ribosome-targeted antibiotics, sensitization was observed on erythromycin, chloramphenicol, kanamycin, puromycin and streptomycin. Minor or no effects were observed with clindamycin, tetracycline and spectinomycin. Surprisingly, the DeltassrA strain is more sensitive than wild type to inhibitors of cell wall synthesis: fosfomycin and ampicillin. No growth difference was observed on drugs with other target sites: ofloxacin, norfloxacin, rifampicin and trimethoprim. Sensitization to antibiotics having target sites other than the ribosome suggests that trans-translation could influence antibiotic-induced stress responses. In trans-translation-deficient bacteria, cell death is significantly enhanced by the two aminoglycosides that induce translational misreading, streptomycin and kanamycin.

  4. Rapid identification of aminoglycoside-induced deafness gene mutations using multiplex real-time polymerase chain reaction.

    Science.gov (United States)

    Huang, Shasha; Xiang, Guangxin; Kang, Dongyang; Wang, Chen; Kong, Yanling; Zhang, Xun; Liang, Shujian; Mitchelson, Keith; Xing, Wanli; Dai, Pu

    2015-07-01

    Exposure to aminoglycoside antibiotics can induce ototoxicity in genetically susceptible individuals carrying certain mitochondrial DNA (mtDNA) mutations (C1494T and A1555G), resulting in hearing loss. So, a rapid diagnostic approach is needed to accurately identify subjects carrying such gene mutations. In the present study, we describe a rapid and reliable four-color, real-time quantitative polymerase chain reaction (qPCR) assay for simultaneously detecting two mtDNA 12S rRNA gene variants, A1555G and C1494T, which are prevalent in the Han Chinese population. This multiplex assay incorporates three allele-specific TaqMan probes labeled with different fluorophores in a single reaction, providing high genotyping accuracy for clinical blood samples. Tests with C1494T, A1555G and wild-type DNA exhibited high sensitivity, specificity, reproducibility and accuracy of discriminating mutations from wild-type. This study shows that this simple and inexpensive method can be used for routine molecular diagnostics and potentially for large-scale genetic screening. Copyright © 2015. Published by Elsevier Ireland Ltd.

  5. Activation of the cryptic aac(6')-Iy aminoglycoside resistance gene of Salmonella by a chromosomal deletion generating a transcriptional fusion.

    Science.gov (United States)

    Magnet, S; Courvalin, P; Lambert, T

    1999-11-01

    Salmonella enterica subsp. enterica serotype Enteritidis BM4361 and BM4362 were isolated from the same patient. BM4361 was susceptible to aminoglycosides, whereas BM4362 was resistant to tobramycin owing to synthesis of a 6'-N-acetyltransferase type I [AAC(6')-I]. Comparative analysis of nucleotide sequences, pulsed-field gel electrophoresis patterns, and Southern hybridizations indicated that the chromosomal aac(6')-Iy genes for the enzyme in both strains were identical and that BM4362 derived from BM4361 following a ca. 60-kb deletion that occurred 1.5 kb upstream from the resistance gene. Northern hybridizations showed that aac(6')-Iy was silent in BM4361 and highly expressed in BM4362 due to a transcriptional fusion. Primer extension mapping identified the transcriptional start site for aac(6')-Iy in BM4362: 5 bp downstream from the promoter of the nmpC gene. Study of the distribution of aac(6')-Iy by PCR and Southern hybridization with a specific probe indicated that the gene, although not found in S. enterica subsp. arizonae, was specific for Salmonella. In this bacterial genus, aac(6')-Iy was located downstream from a cluster of seven open reading frames analogous to an Escherichia coli locus that encodes enzymes putatively involved in carbohydrate transport or metabolism. This genomic environment suggests a role in the catabolism of a specific sugar for AAC(6')-Iy in Salmonella.

  6. Aminoglycoside resistance of Pseudomonas aeruginosa in cystic fibrosis results from convergent evolution in the mexZ gene.

    Science.gov (United States)

    Prickett, Michelle H; Hauser, Alan R; McColley, Susanna A; Cullina, Joanne; Potter, Eileen; Powers, Cathy; Jain, Manu

    2017-01-01

    Aminoglycoside (AG) resistance of Pseudomonas aeruginosa in cystic fibrosis (CF) is associated with poorer clinical outcomes and is usually due to overexpression of the efflux pump MexXY. MexXY is regulated by mexZ, one of the most commonly mutated genes in CF P. aeruginosa isolates. Little is known about the evolutionary relationship between AG resistance, MexXY expression and mexZ mutations. To test the hypothesis that AG resistance in P. aeruginosa develops in parallel with higher MexXY expression and mexZ mutations. CF P. aeruginosa isolates were compared for chronically infected (CI) adults, CI children and children with new infection. One P. aeruginosa isolate from each patient was analysed for mexZ mutations, mexY mRNA expression and amikacin resistance. 56 patients with CF were enrolled: 21 children with new P. aeruginosa infection, 18 CI children and 17 CI adults. Amikacin resistance and mexY mRNA expression were higher in cohorts with longer P. aeruginosa infection. The prevalence of non-conservative mexZ mutations was 0%, 33% and 65% in children with new infection, CI children and CI adults, respectively. The same trend was seen in the ratio of non-conservative to non-synonymous mexZ mutations. Of isolates with non-conservative mexZ mutations, 59% were amikacin-resistant compared with 18% of isolates with non-synonymous mutations. The doubling rate of amikacin resistance and non-conservative mexZ mutations was approximately 5 years. P. aeruginosa mexZ mutations undergo positive selection resulting in increased mexY mRNA expression and amikacin resistance and likely play a role in bacterial adaption in the CF lung. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  7. Reduced Chance of Hearing Loss Associated with Therapeutic Drug Monitoring of Aminoglycosides in the Treatment of Multidrug-Resistant Tuberculosis.

    Science.gov (United States)

    van Altena, R; Dijkstra, J A; van der Meer, M E; Borjas Howard, J F; Kosterink, J G W; van Soolingen, D; van der Werf, T S; Alffenaar, J W C

    2017-03-01

    Hearing loss and nephrotoxicity are associated with prolonged treatment duration and higher dosage of amikacin and kanamycin. In our tuberculosis center, we used therapeutic drug monitoring (TDM) targeting preset pharmacokinetic/pharmacodynamic (PK/PD) surrogate endpoints in an attempt to maintain efficacy while preventing (oto)toxicity. To evaluate this strategy, we retrospectively evaluated medical charts of tuberculosis (TB) patients treated with amikacin or kanamycin in the period from 2000 to 2012. Patients with culture-confirmed multiresistant or extensively drug-resistant tuberculosis (MDR/XDR-TB) receiving amikacin or kanamycin as part of their TB treatment for at least 3 days were eligible for inclusion in this retrospective study. Clinical data, including maximum concentration ( C max ), C min , and audiometry data, were extracted from the patients' medical charts. A total of 80 patients met the inclusion criteria. The mean weighted C max /MIC ratios obtained from 57 patients were 31.2 for amikacin and 12.3 for kanamycin. The extent of hearing loss was limited and correlated with the cumulative drug dose per kg of body weight during daily administration. At follow-up, 35 (67.3%) of all patients had successful outcome; there were no relapses. At a median dose of 6.5 mg/kg, a correlation was found between the dose per kg of body weight during daily dosing and the extent of hearing loss in dB at 8,000 Hz. These findings suggest that the efficacy at this lower dosage is maintained with limited toxicity. A randomized controlled trial should provide final proof of the safety and efficacy of TDM-guided use of aminoglycosides in MDR-TB treatment. Copyright © 2017 American Society for Microbiology.

  8. Robustness analysis of culturing perturbations on Escherichia coli colony biofilm beta-lactam and aminoglycoside antibiotic tolerance

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    Jimenez-Taracido Lourdes

    2010-07-01

    Full Text Available Abstract Background Biofilms are ubiquitous. For instance, the majority of medical infections are thought to involve biofilms. However even after decades of investigation, the in vivo efficacy of many antimicrobial strategies is still debated suggesting there is a need for better understanding of biofilm antimicrobial tolerances. The current study's goal is to characterize the robustness of biofilm antibiotic tolerance to medically and industrially relevant culturing perturbations. By definition, robust systems will return similar, predictable responses when perturbed while non-robust systems will return very different and potentially unpredictable responses. The predictability of an antibiotic tolerance response is essential to developing, testing, and employing antimicrobial strategies. Results The antibiotic tolerance of Escherichia coli colony biofilms was tested against beta-lactam and aminoglycoside class antibiotics. Control scenario tolerances were compared to tolerances under culturing perturbations including 1 different nutritional environments 2 different temperatures 3 interruption of cellular quorum sensing and 4 different biofilm culture ages. Here, antibiotic tolerance was defined in terms of culturable biofilm cells recovered after a twenty four hour antibiotic treatment. Colony biofilm antibiotic tolerances were not robust to perturbations. Altering basic culturing parameters like nutritional environment or temperature resulted in very different, non-intuitive antibiotic tolerance responses. Some minor perturbations like increasing the glucose concentration from 0.1 to 1 g/L caused a ten million fold difference in culturable cells over a twenty four hour antibiotic treatment. Conclusions The current study presents a basis for robustness analysis of biofilm antibiotic tolerance. Biofilm antibiotic tolerance can vary in unpredictable manners based on modest changes in culturing conditions. Common antimicrobial testing methods

  9. High Prevalence and Predominance of the aph(2″)-If Gene Conferring Aminoglycoside Resistance in Campylobacter.

    Science.gov (United States)

    Yao, Hong; Liu, Dejun; Wang, Yang; Zhang, Qijing; Shen, Zhangqi

    2017-05-01

    Campylobacter is a major foodborne pathogen, and previous studies revealed that Campylobacter isolates from food-producing animals are increasingly resistant to gentamicin in China. The molecular epidemiology and genetic mechanisms responsible for gentamicin resistance in China have not been well understood. In this study, 607 Campylobacter isolates of chicken and swine origins collected in 2014 were analyzed, revealing that 15.6% (25/160) of the Campylobacter jejuni isolates and 79.9% (357/447) of the Campylobacter coli isolates were resistant to gentamicin. PCR detection of the gentamicin resistance genes indicated that aph(2″)-If was more prevalent than the previously identified aacA/aphD gene and has become the dominant gentamicin resistance determinant in Campylobacter Transformation and whole-genome sequencing as well as long-range PCR discovered that aph(2″)-If was located on a chromosomal segment inserted between two conserved genes, Cj0299 and panB Cloning of aph(2″)-If into gentamicin-susceptible C. jejuni NCTC 11168 confirmed its function in conferring high-level resistance to gentamicin and kanamycin. Molecular typing by pulsed-field gel electrophoresis suggested that both regional expansion of a particular clone and horizontal transmission were involved in the dissemination of the aph(2″)-If gene in Campylobacter To our knowledge, this is the first report describing the high prevalence of a chromosomally encoded aph(2″)-If gene in Campylobacter The high prevalence and predominance of this gene might be driven by the use of aminoglycoside antibiotics in food animal production in China and potentially compromise the usefulness of gentamicin as a therapeutic agent for Campylobacter -associated systemic infection. Copyright © 2017 American Society for Microbiology.

  10. Meropenem potentiation of aminoglycoside activity against Pseudomonas aeruginosa: involvement of the MexXY-OprM multidrug efflux system.

    Science.gov (United States)

    Poole, Keith; Gilmour, Christie; Farha, Maya A; Parkins, Michael D; Klinoski, Rachael; Brown, Eric D

    2018-02-06

    To assess the ability of meropenem to potentiate aminoglycoside (AG) activity against laboratory and AG-resistant cystic fibrosis (CF) isolates of Pseudomonas aeruginosa and to elucidate its mechanism of action. AG resistance gene deletions were engineered into P. aeruginosa laboratory and CF isolates using standard gene replacement technology. Susceptibility to AGs ± meropenem (at ½ MIC) was assessed using a serial 2-fold dilution assay. mexXY expression and MexXY-OprM efflux activity were quantified using quantitative PCR and an ethidium bromide accumulation assay, respectively. A screen for agents that rendered WT P. aeruginosa susceptible to a sub-MIC concentration of the AG paromomycin identified the carbapenem meropenem, which potentiated several additional AGs. Meropenem potentiation of AG activity was largely lost in a mutant lacking the MexXY-OprM multidrug efflux system, an indication that it was targeting this efflux system in enhancing P. aeruginosa susceptibility to AGs. Meropenem failed to block AG induction of mexXY expression or MexXY-OprM efflux activity, suggesting that it may be interfering with some MexXY-dependent process linked to AG susceptibility. Meropenem potentiated AG activity versus AG-resistant CF isolates, enhancing susceptibility to at least one AG in all isolates and susceptibility to all tested AGs in 50% of the isolates. Notably, meropenem potentiation of AG activity was linked to MexXY in some but not all CF isolates in which this was examined. Meropenem potentiates AG activity against laboratory and CF strains of P. aeruginosa, both dependent on and independent of MexXY, highlighting the complexity of AG resistance in this organism. © The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Combinations of β-Lactam or Aminoglycoside Antibiotics with Plectasin Are Synergistic against Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus

    Science.gov (United States)

    Hu, Yanmin; Liu, Alexander; Vaudrey, James; Vaiciunaite, Brigita; Moigboi, Christiana; McTavish, Sharla M.; Kearns, Angela; Coates, Anthony

    2015-01-01

    Bacterial infections remain the leading killer worldwide which is worsened by the continuous emergence of antibiotic resistance. In particular, methicillin-sensitive (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) are prevalent and the latter can be difficult to treat. The traditional strategy of novel therapeutic drug development inevitably leads to emergence of resistant strains, rendering the new drugs ineffective. Therefore, rejuvenating the therapeutic potentials of existing antibiotics offers an attractive novel strategy. Plectasin, a defensin antimicrobial peptide, potentiates the activities of other antibiotics such as β-lactams, aminoglycosides and glycopeptides against MSSA and MRSA. We performed in vitro and in vivo investigations to test against genetically diverse clinical isolates of MSSA (n = 101) and MRSA (n = 115). Minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. The effects of combining plectasin with β-lactams, aminoglycosides and glycopeptides were examined using the chequerboard method and time kill curves. A murine neutropenic thigh model and a murine peritoneal infection model were used to test the effect of combination in vivo. Determined by factional inhibitory concentration index (FICI), plectasin in combination with aminoglycosides (gentamicin, neomycin or amikacin) displayed synergistic effects in 76-78% of MSSA and MRSA. A similar synergistic response was observed when plectasin was combined with β-lactams (penicillin, amoxicillin or flucloxacillin) in 87–89% of MSSA and MRSA. Interestingly, no such interaction was observed when plectasin was paired with vancomycin. Time kill analysis also demonstrated significant synergistic activities when plectasin was combined with amoxicillin, gentamicin or neomycin. In the murine models, plectasin at doses as low as 8 mg/kg augmented the activities of amoxicillin and gentamicin in successful treatment of MSSA and MRSA infections. We

  12. Ex vivo treatment with a novel synthetic aminoglycoside NB54 in primary fibroblasts from Rett syndrome patients suppresses MECP2 nonsense mutations.

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    Manuela Vecsler

    Full Text Available BACKGROUND: Nonsense mutations in the X-linked methyl CpG-binding protein 2 (MECP2 comprise a significant proportion of causative MECP2 mutations in Rett syndrome (RTT. Naturally occurring aminoglycosides, such as gentamicin, have been shown to enable partial suppression of nonsense mutations related to several human genetic disorders, however, their clinical applicability has been compromised by parallel findings of severe toxic effects. Recently developed synthetic NB aminoglycosides have demonstrated significantly improved effects compared to gentamicin evident in substantially higher suppression and reduced acute toxicity in vitro. RESULTS: We performed comparative study of suppression effects of the novel NB54 and gentamicin on three MECP2 nonsense mutations (R294X, R270X and R168X common in RTT, using ex vivo treatment of primary fibroblasts from RTT patients harboring these mutations and testing for the C-terminal containing full-length MeCP2. We observed that NB54 induces dose-dependent suppression of MECP2 nonsense mutations more efficiently than gentamicin, which was evident at concentrations as low as 50 µg/ml. NB54 read-through activity was mutation specific, with maximal full-length MeCP2 recovery in R168X (38%, R270X (27% and R294X (18%. In addition, the recovered MeCP2 was translocated to the cell nucleus and moreover led to parallel increase in one of the most important MeCP2 downstream effectors, the brain derived neurotrophic factor (BDNF. CONCLUSION: Our findings suggest that NB54 may induce restoration of the potentially functional MeCP2 in primary RTT fibroblasts and encourage further studies of NB54 and other rationally designed aminoglycoside derivatives as potential therapeutic agents for nonsense MECP2 mutations in RTT.

  13. Identification of a Novel 6′-N-Aminoglycoside Acetyltransferase, AAC(6′)-Iak, from a Multidrug-Resistant Clinical Isolate of Stenotrophomonas maltophilia

    Science.gov (United States)

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

    2014-01-01

    Stenotrophomonas maltophilia IOMTU250 has a novel 6′-N-aminoglycoside acetyltransferase-encoding gene, aac(6′)-Iak. The encoded protein, AAC(6′)-Iak, consists of 153 amino acids and has 86.3% identity to AAC(6′)-Iz. Escherichia coli transformed with a plasmid containing aac(6′)-Iak exhibited decreased susceptibility to arbekacin, dibekacin, neomycin, netilmicin, sisomicin, and tobramycin. Thin-layer chromatography showed that AAC(6′)-Iak acetylated amikacin, arbekacin, dibekacin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, and tobramycin but not apramycin, gentamicin, or lividomycin. PMID:25092711

  14. Identification of a novel 6'-N-aminoglycoside acetyltransferase, AAC(6')-Iak, from a multidrug-resistant clinical isolate of Stenotrophomonas maltophilia.

    Science.gov (United States)

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

    2014-10-01

    Stenotrophomonas maltophilia IOMTU250 has a novel 6'-N-aminoglycoside acetyltransferase-encoding gene, aac(6')-Iak. The encoded protein, AAC(6')-Iak, consists of 153 amino acids and has 86.3% identity to AAC(6')-Iz. Escherichia coli transformed with a plasmid containing aac(6')-Iak exhibited decreased susceptibility to arbekacin, dibekacin, neomycin, netilmicin, sisomicin, and tobramycin. Thin-layer chromatography showed that AAC(6')-Iak acetylated amikacin, arbekacin, dibekacin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, and tobramycin but not apramycin, gentamicin, or lividomycin. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  15. External validation of aminoglycoside models used in web calculators and clinical decision support systems after laboratory conversion to serum creatinine isotope dilution mass spectrometry assay.

    Science.gov (United States)

    Wolowich, William R; Steinberg, Jennifer G

    2012-04-01

    Models to predict gentamicin t(½) from serum creatinine (SCr) estimated creatinine clearance (CrCl) are currently being incorporated into smart-device applications and clinical decision support modules without external validation. The aim of this study was to determine whether such models remain viable after conversion to isotope dilution mass spectrometry (IDMS) SCr assay. This study analyzed data from retrospective reviews of the medical records of nonobese adults receiving the aminoglycoside gentamicin and having ≥2 evaluable serum gentamicin concentrations after laboratory IDMS SCr conversion, from January 2008 to August 2009, at a tertiary care hospital in Florida. A literature search found a number of cited aminoglycoside models. This group of models was classified as group 1. The World Wide Web was also searched for the term aminoglycoside dosing calculators, with 6 models found and referred to as group 2. Predictive performance measures were used to compare the model results with the t(½) calculated from gentamicin concentrations using the Nelder-Mead algorithm. The records of 39 patients met the inclusion criteria (23 men, 16 women; age range, 18-86 years; range of estimated CrCl, 55-115 mL/min) and provided the "gold standard" aminoglycoside t(½). A gentamicin t(½) was predicted from several published models (group 1) and from other models used in online smart-device applications (group 2) and clinical decision modules. The median (interquartile range) root mean square errors were 0.48 (0.44 to 0.65) and 0.48 (0.45 to 0.70) hours from group-1 and -2 models, respectively. The median mean relative prediction errors were 9% (-14% to +13%) and 11% (+1% to +21%) from groups 1 and 2. The median mean absolute prediction errors were 21% (19% to 28%) and 21% (20% to 30%) from groups 1 and 2. Adjusting SCr by +20% improved the predictive ability in 3 of 12 cited models and in 5 of 6 models used in applications. Models to predict gentamicin t(½) should be

  16. The BpeAB-OprB efflux pump of Burkholderia pseudomallei 1026b does not play a role in quorum sensing, virulence factor production, or extrusion of aminoglycosides but is a broad-spectrum drug efflux system.

    Science.gov (United States)

    Mima, Takehiko; Schweizer, Herbert P

    2010-08-01

    Most Burkholderia pseudomallei strains are intrinsically aminoglycoside resistant, mainly due to AmrAB-OprA-mediated efflux. Rare naturally occurring or genetically engineered mutants lacking this pump are aminoglycoside susceptible despite the fact that they also encode and express BpeAB-OprB, which was reported to mediate efflux of aminoglycosides in the Singapore strain KHW. To reassess the role of BpeAB-OprB in B. pseudomallei aminoglycoside resistance, we used mutants overexpressing or lacking this pump in either AmrAB-OprA-proficient or -deficient strain 1026b backgrounds. Our data show that BpeAB-OprB does not mediate efflux of aminoglycosides but is a multidrug efflux system which extrudes macrolides, fluoroquinolones, tetracyclines, acriflavine, and, to a lesser extent, chloramphenicol. Phylogenetically, BpeAB-OprB is closely related to Pseudomonas aeruginosa MexAB-OprM, which has a similar substrate spectrum. AmrAB-OprA is most closely related to MexXY, the only P. aeruginosa efflux pump known to extrude aminoglycosides. Since BpeAB-OprB in strain KHW was also implicated in playing a major role in export of acylated homoserine lactone (AHL) quorum-sensing molecules and in expression of diverse virulence factors, we explored whether this was also true in the strain 1026b background. The results showed that BpeAB-OprB was not required for AHL export, and mutants lacking this efflux system exhibited normal swimming motility and siderophore production, which were severely impaired in KHW bpeAB-oprB mutants. Biofilm formation was impaired in 1026b Delta(amrRAB-oprA) and Delta(amrRAB-oprA) Delta(bpeAB-oprB) mutants. At present, we do not know why our BpeAB-OprB susceptibility and virulence factor expression results with 1026b and its derivatives are different from those previously published for Singapore strain KHW.

  17. Analysis of Triclosan-Selected Salmonella enterica Mutants of Eight Serovars Revealed Increased Aminoglycoside Susceptibility and Reduced Growth Rates

    Science.gov (United States)

    Rensch, Ulrike; Klein, Guenter; Kehrenberg, Corinna

    2013-01-01

    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 decreased

  18. Synthesis of magnetic graphene/mesoporous silica composites with boronic acid-functionalized pore-walls for selective and efficient residue analysis of aminoglycosides in milk.

    Science.gov (United States)

    Feng, Jianan; She, Xiaojian; He, Xinying; Zhu, Jinglin; Li, Yan; Deng, Chunhui

    2018-01-15

    In this study, magnetic graphene/mesoporous silica composites with boronic acid-functionalized pore-walls were synthesized for the first time by a two-step post-graft method. The obtained nano-composites were proven to hold many attractive features such as large specific surface area, uniform mesopores, high magnetic responsibility, and boronic acid-functionalized inner pore-walls. Aminoglycoside residues in milk were extracted using MG@mSiO 2 -APB composites as restricted access matrix dispersive solid phase extraction adsorbents through the interaction between boronic acid groups and glucoside structures. Extraction conditions were optimized by studying the SPE parameters. Limits of detection of the method were as low as 5ngmL -1 for streptomycin) and 2ngmL -1 for dihydrostreptomycin. Finally, magnetic graphene/mesoporous silica composites with boronic acid-functionalized pore-walls were successfully applied to residue analysis in milk samples. Compared to the traditional extraction methods, using this nano-composites for aminoglycoside residues analysis in milk is more sensitive, effective and convenient. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. 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.

  20. [Prevalence of Enterococcus faecalis and Enterococcus faecium with high resistance to aminoglycosides in the cities of Resistencia and Corrientes, Republic of Argentina].

    Science.gov (United States)

    Ronconi, M C; Merino, L A

    2000-02-01

    The objective of this study was characterize the prevalence of high-level aminoglycosides resistance (HLRA) in Enterococcus faecalis and E. faecium, determine the relationship between high-level gentamicin resistance (HLGR) and other aminoglycosides, and their distribution according clinical samples (blood, urine and others). A total of 177 strain (157 E. faecalis and 20 E. faecium) isolated from 1996 to 1998 were studied. They were identified by using classic methods. Their susceptibility to gentamicin, streptomycin, and kanamycin was tested by the disk diffusion technique using high-level disks in agar Müller Hinton. E. faecalis showed HLRG of 28.7%, streptomycin 28.7% and kanamycin 37.6%, E. faecium showed 50%, 40%, and 60% respectively. The strains with HLRA have a tendency to high-level resistances to streptomycin and kanamycin (p < 0.0005). Statistical analysis demonstrated significative differences among strains with HLRA isolated from blood, urine and other clinical samples (p < 0.0005 to gentamicin and streptomycin and 0.004 < p < 0.007 to kanamycin). The prevalence of HLRA enterococci found in the area os this study, justify its detection, particularity in cases of serious infections.

  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. 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

  3. Brief communication: detection of clinical Klebsiella pneumoniae isolates from China containing transferable quinolone resistance determinants exhibiting resistance to both aminoglycoside and β-lactams.

    Science.gov (United States)

    Xue, Xinying; Pan, Lei; Zhang, Naxin; Liu, Yuxia; Luo, Yanping; Zhou, Guang; Guan, Xizhou

    2014-01-01

    Though aminoglycosides are routinely used clinically as antimicrobial agents for the treatment of severe infections due to Klebsiella pneumoniae, resistance to the same is an increasing problem. One such resistance mechanism is the production of 16S rRNA methylases. The objective of the current study was to investigate the prevalence and molecular epidemology of 16S rRNA methylase genes among 43 K. pneumoniae isolates (each of which had at least one PQMR gene and ciprofloxacin minimum inhibitory concentration greater than 0.25) recovered from nine tertiary hospitals in China. Our results suggest great genetic variation in terms of 16S rRNA methylase gene of K. pneumoniae hosts containing at least one PQMR gene. This further reinforces the clinical and systemic urgency required to characterize and block their transmission routes.

  4. A rapid SPE-based analytical method for UPLC/MS/MS determination of aminoglycoside antibiotic residues in bovine milk, muscle, and kidney.

    Science.gov (United States)

    Young, Michael S; van Tran, Kim; Goh, Evelyn; Shia, Jeremy C

    2014-01-01

    An SPE-based cleanup protocol was developed for ultra-performance LC (UPLC)/MS/MS determination of residues of the common aminoglycoside antibiotics streptomycin, dihydrostreptomycin, neomycin, and gentamicin in bovine milk, kidney, and muscle. Recoveries for all compounds except neomycin ranged from 80 to 104% for all matrixes studied; recoveries for neomycin ranged from 71 to 84%. Intraday and interday precision data were under 15% for all sample matrixes. Compared with other recently reported cleanup methods, less sample is required, the use of potentially dangerous reagents is minimized, and fewer manipulations are required by the analyst. A high throughput 96-well plate format was used for SPE cleanup and UPLC/MS analysis.

  5. 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.

  6. Structure of the bifunctional aminoglycoside-resistance enzyme AAC(6')-Ie-APH(2'')-Ia revealed by crystallographic and small-angle X-ray scattering analysis.

    Science.gov (United States)

    Smith, Clyde A; Toth, Marta; Weiss, Thomas M; Frase, Hilary; Vakulenko, Sergei B

    2014-10-01

    Broad-spectrum resistance to aminoglycoside antibiotics in clinically important Gram-positive staphylococcal and enterococcal pathogens is primarily conferred by the bifunctional enzyme AAC(6')-Ie-APH(2'')-Ia. This enzyme possesses an N-terminal coenzyme A-dependent acetyltransferase domain [AAC(6')-Ie] and a C-terminal GTP-dependent phosphotransferase domain [APH(2'')-Ia], and together they produce resistance to almost all known aminoglycosides in clinical use. Despite considerable effort over the last two or more decades, structural details of AAC(6')-Ie-APH(2'')-Ia have remained elusive. In a recent breakthrough, the structure of the isolated C-terminal APH(2'')-Ia enzyme was determined as the binary Mg2GDP complex. Here, the high-resolution structure of the N-terminal AAC(6')-Ie enzyme is reported as a ternary kanamycin/coenzyme A abortive complex. The structure of the full-length bifunctional enzyme has subsequently been elucidated based upon small-angle X-ray scattering data using the two crystallographic models. The AAC(6')-Ie enzyme is joined to APH(2'')-Ia by a short, predominantly rigid linker at the N-terminal end of a long α-helix. This α-helix is in turn intrinsically associated with the N-terminus of APH(2'')-Ia. This structural arrangement supports earlier observations that the presence of the intact α-helix is essential to the activity of both functionalities of the full-length AAC(6')-Ie-APH(2'')-Ia enzyme.

  7. Ribosomal Protein S12 and Aminoglycoside Antibiotics Modulate A-site mRNA Cleavage and Transfer-Messenger RNA Activity in Escherichia coli*

    Science.gov (United States)

    Holberger, Laura E.; Hayes, Christopher S.

    2009-01-01

    Translational pausing in Escherichia coli can lead to mRNA cleavage within the ribosomal A-site. A-site mRNA cleavage is thought to facilitate transfer-messenger RNA (tmRNA)·SmpB- mediated recycling of stalled ribosome complexes. Here, we demonstrate that the aminoglycosides paromomycin and streptomycin inhibit A-site cleavage of stop codons during inefficient translation termination. Aminoglycosides also induced stop codon read-through, suggesting that these antibiotics alleviate ribosome pausing during termination. Streptomycin did not inhibit A-site cleavage in rpsL mutants, which express streptomycin-resistant variants of ribosomal protein S12. However, rpsL strains exhibited reduced A-site mRNA cleavage compared with rpsL+ cells. Additionally, tmRNA·SmpB-mediated SsrA peptide tagging was significantly reduced in several rpsL strains but could be fully restored in a subset of mutants when treated with streptomycin. The streptomycin-dependent rpsL(P90K) mutant also showed significantly lower levels of A-site cleavage and tmRNA·SmpB activity. Mutations in rpsD (encoding ribosomal protein S4), which suppressed streptomycin dependence, were able to partially restore A-site cleavage to rpsL(P90K) cells but failed to increase tmRNA·SmpB activity. Taken together, these results show that perturbations to A-site structure and function modulate A-site mRNA cleavage and tmRNA·SmpB activity. We propose that tmRNA·SmpB binds to streptomycin-resistant rpsL ribosomes less efficiently, leading to a partial loss of ribosome rescue function in these mutants. PMID:19776006

  8. Ribosomal protein S12 and aminoglycoside antibiotics modulate A-site mRNA cleavage and transfer-messenger RNA activity in Escherichia coli.

    Science.gov (United States)

    Holberger, Laura E; Hayes, Christopher S

    2009-11-13

    Translational pausing in Escherichia coli can lead to mRNA cleavage within the ribosomal A-site. A-site mRNA cleavage is thought to facilitate transfer-messenger RNA (tmRNA).SmpB- mediated recycling of stalled ribosome complexes. Here, we demonstrate that the aminoglycosides paromomycin and streptomycin inhibit A-site cleavage of stop codons during inefficient translation termination. Aminoglycosides also induced stop codon read-through, suggesting that these antibiotics alleviate ribosome pausing during termination. Streptomycin did not inhibit A-site cleavage in rpsL mutants, which express streptomycin-resistant variants of ribosomal protein S12. However, rpsL strains exhibited reduced A-site mRNA cleavage compared with rpsL(+) cells. Additionally, tmRNA.SmpB-mediated SsrA peptide tagging was significantly reduced in several rpsL strains but could be fully restored in a subset of mutants when treated with streptomycin. The streptomycin-dependent rpsL(P90K) mutant also showed significantly lower levels of A-site cleavage and tmRNA.SmpB activity. Mutations in rpsD (encoding ribosomal protein S4), which suppressed streptomycin dependence, were able to partially restore A-site cleavage to rpsL(P90K) cells but failed to increase tmRNA.SmpB activity. Taken together, these results show that perturbations to A-site structure and function modulate A-site mRNA cleavage and tmRNA.SmpB activity. We propose that tmRNA.SmpB binds to streptomycin-resistant rpsL ribosomes less efficiently, leading to a partial loss of ribosome rescue function in these mutants.

  9. 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

  10. 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

  11. Aminoglycoside detection using a universal ELISA binding procedure onto polystyrene microtiter plates in comparison with HPLC analysis and microbiological agar-diffusion assay.

    Science.gov (United States)

    Sachetelli, S; Beaulac, C; Lagacé, J

    1998-01-08

    The use of enzyme-linked immunosorbent assay for the detection of aminoglycosides has been hindered due to low molecular weight compound adsorption to solid phases. Here, we describe an enzyme-linked immunosorbent assay based on the treatment of polystyrene microtiter plates with Alcian blue prepared in acetic acid prior to coating with the antibiotic. Whereas no detection of tobramycin was possible on commercially treated or untreated enzyme-linked immunosorbent assay plates, the Alcian blue treatment permitted detection of 0.025 and 0.05 microg ml(-1) of tobramycin respectively using 0.05 and 0.1% of Alcian blue with a coefficient of variation of 1.85 and 7.69%, respectively. Comparative studies of five tobramycin samples of unknown quantity using enzyme-linked immunosorbent assay and high-performance liquid chromatography gave equivalent results while those done via microbiological agar-diffusion assay were an overestimation of the actual quantity. The use of the Alcian blue pretreatment enzyme-linked immunosorbent assay procedure has permitted, in previous studies, the measure of antibodies against synthetic peptides and phospholipids. Subsequently, our demonstration of the sensitivity and reliability of this method in the quantification of tobramycin strongly suggests that the use of Alcian blue pretreatment in enzyme-linked immunosorbent assay can be applied universally to avert molecule immobilization problems on solid phases.

  12. Domain Dissection and Characterization of the Aminoglycoside Resistance Enzyme ANT(3″)-Ii/AAC(6′)-IId from Serratia marcescens

    Science.gov (United States)

    Green, Keith D.; Garneau-Tsodikova, Sylvie

    2013-01-01

    Aminoglycosides (AGs) are broad-spectrum antibiotics whose constant use and presence in growth environment has led bacteria to develop resistance mechanisms to aid in their survival. A common mechanism of resistance to AGs is their chemical modification (nucleotidylation, phosphorylation, or acetylation) by AG-modifying enzymes (AMEs). Through evolution, fusion of two AME-encoding genes has resulted in bifunctional enzymes with broader spectrum of activity. Serratia marcescens, a human enteropathogen, contains such a bifunctional enzyme, ANT(3″)-Ii/AAC(6′)-IId. To gain insight into the role, effect, and importance of the union of ANT(3″)-Ii and AAC(6′)-IId in this bifunctional enzyme, we separated the two domains and compared their activity to that of the full-length enzyme. We performed a thorough comparison of the substrate and cosubstrate profiles as well as kinetic characterization of the bifunctional ANT(3″)-Ii/AAC(6′)-IId and its individually expressed components. PMID:23485681

  13. Activation of the Cryptic aac(6′)-Iy Aminoglycoside Resistance Gene of Salmonella by a Chromosomal Deletion Generating a Transcriptional Fusion

    Science.gov (United States)

    Magnet, Sophie; Courvalin, Patrice; Lambert, Thierry

    1999-01-01

    Salmonella enterica subsp. enterica serotype Enteritidis BM4361 and BM4362 were isolated from the same patient. BM4361 was susceptible to aminoglycosides, whereas BM4362 was resistant to tobramycin owing to synthesis of a 6′-N-acetyltransferase type I [AAC(6′)-I]. Comparative analysis of nucleotide sequences, pulsed-field gel electrophoresis patterns, and Southern hybridizations indicated that the chromosomal aac(6′)-Iy genes for the enzyme in both strains were identical and that BM4362 derived from BM4361 following a ca. 60-kb deletion that occurred 1.5 kb upstream from the resistance gene. Northern hybridizations showed that aac(6′)-Iy was silent in BM4361 and highly expressed in BM4362 due to a transcriptional fusion. Primer extension mapping identified the transcriptional start site for aac(6′)-Iy in BM4362: 5 bp downstream from the promoter of the nmpC gene. Study of the distribution of aac(6′)-Iy by PCR and Southern hybridization with a specific probe indicated that the gene, although not found in S. enterica subsp. arizonae, was specific for Salmonella. In this bacterial genus, aac(6′)-Iy was located downstream from a cluster of seven open reading frames analogous to an Escherichia coli locus that encodes enzymes putatively involved in carbohydrate transport or metabolism. This genomic environment suggests a role in the catabolism of a specific sugar for AAC(6′)-Iy in Salmonella. PMID:10542165

  14. High-level aminoglycoside resistance in Enterococcus faecalis and Enterococcus faecium causing invasive infection: Twelve-year surveillance in the Minami Ibaraki Area.

    Science.gov (United States)

    Osuka, Hanako; Nakajima, Jun; Oishi, Tsuyoshi; Funayama, Yasunori; Ebihara, Tsugio; Ishikawa, Hiroichi; Saito, Kazuto; Koganemaru, Hiroshi; Hitomi, Shigemi

    2016-01-01

    We examined prevalence of high-level aminoglycoside resistance (HLAR) in Enterococcus faecalis and Enterococcus faecium causing invasive infection in the Minami Ibaraki Area. Ten strains of both species each, recovered from the blood or the cerebrospinal fluid between 2003 and 2014, were randomly selected every year. High-level resistance to gentamicin (HLR-GM) and streptomycin (HLR-SM) was detected in 34% (41 of 120 strains) and 18% (21) of E. faecalis and 9% (11) and 39% (48) of E. faecium, respectively. In comparisons of the proportions among three four-year periods, HLR-SM among E. faecium was significantly lower in the 2011-2014 period. All strains with HLR-GM were positive for the aac(6')-Ie-aph(2″)-Ia gene. The ant(6')-Ia gene was detected in all with HLR-SM except for one E. faecalis strain. The present study showed that prevalence of HLR-GM among E. faecalis and E. faecium causing invasive infection in this area was nearly equivalent to that described in previous studies in Japan and that proportions of strains with HLAR did not vary during the study period except for that of HLR-SM among E. faecium. Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  15. In-vivo impact of the MexXY efflux system on aminoglycoside efficacy in an experimental model of Pseudomonas aeruginosa pneumonia treated with tobramycin.

    Science.gov (United States)

    Martha, B; Croisier, D; Durand, D; Hocquet, D; Plesiat, P; Piroth, L; Portier, H; Chavanet, P

    2006-05-01

    Aminoglycosides are of major importance in treating Pseudomonas aeruginosa pneumonia (PAP). However, their efficacy may be compromised by low-level resistance caused by the inducible MexXY multidrug efflux pump. In the present study, the impact of the MexXY efflux pump was investigated in vivo in an experimental model of PAP in rabbits treated with intravenous tobramycin. Three strains were used to induce PAP in rabbits: PAO1 (wild-type strain; MIC 1 mg/L), mutant 11B (mexX::Tn501; no expression of MexXY; MIC 0.5 mg/L) and mutant MutGR1 (MexZ null; constitutive expression of MexXY; MIC 2 mg/L). Five hours after inoculation, treatment with tobramycin (10 mg/kg) was implemented (peak serum concentration 30 mg/L). The animals were killed humanely 48 h after inoculation, and the residual pulmonary bacterial concentration was determined. Selection of bacteria expressing MexXY was determined by plating lung homogenates on agar plates containing antibiotic. Mean bacterial counts (log(10) CFU/g) for treated vs. untreated rabbits were 6.26 and 8.13 (p system to this low level of tobramycin efficacy is modest. Finally, this model appears to be suitable for the investigation of new anti-pseudomonal therapeutic strategies.

  16. Role of the multidrug efflux system MexXY in the emergence of moderate resistance to aminoglycosides among Pseudomonas aeruginosa isolates from patients with cystic fibrosis.

    Science.gov (United States)

    Vogne, Christelle; Aires, Julio Ramos; Bailly, Christiane; Hocquet, Didier; Plésiat, Patrick

    2004-05-01

    This study investigates the role of active efflux system MexXY in the emergence of aminoglycoside (AG) resistance among cystic fibrosis (CF) isolates of Pseudomonas aeruginosa. Three genotypically related susceptible and resistant (S/R) bacterial pairs and three other AG-resistant CF strains were compared to four non-CF strains moderately resistant to AGs. As demonstrated by immunoblot experiments, pump MexY was strongly overproduced in all of the resistant bacteria. This MexXY upregulation was associated with a 2- to 16-fold increase in the MICs of AGs in the S/R pairs and lower intracellular accumulation of dihydrostreptomycin. Alterations in mexZ, the repressor gene of operon mexXY, were found in all of the AG-resistant CF isolates and in one non-CF strain. Complementation of these bacteria with a plasmid-borne mexZ gene dramatically reduced the MICs of AGs, thus highlighting the role played by MexXY in the development of moderate resistance in CF patients. In contrast, complementation of the three non-CF strains showing wild-type mexZ genes left residual levels of resistance to AGs. These data indicate that a locus different from mexZ may be involved in overproduction of MexXY and that other nonenzymatic mechanisms contribute to AG resistance in P. aeruginosa.

  17. Evaluation on the Use of β-Lactamase and Aminoglycoside Modifying Enzyme Gene Sequences as Markers for the Early Detection of Antibiotic Resistance Profile of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Victor A. Doss

    2004-01-01

    Full Text Available Pseudomonas aeruginosa is one of the major causes of infections including the hospital acquired (Nosocomial infections. Detection of them and their antibiotic resistance profile by conventional method takes about three days. Recently, DNA based diagnostic methods are being used for the identification of the pathogens. Hence we have tested a rapid and sensitive method using DNA sequences as markers for detecting the presence of three genes coding for the enzymes that inactivate the two most commonly used Anti-pseudomonadal drugs such as β-lactam antibiotics (Penicillin, and its derivatives and Aminoglycosides such as Gentamicin, Tobramycin, Amikacin, Streptomycin. The internal region of these genes were used for designing and synthesizing primers and these primers were used in Polymerase Chain Reaction (PCR to screen for the presence of these genes in the clinical isolates and to label them non-radioactively with Biotin. They in turn were used to detect the presence of the antibiotic resistance genes in the clinical isolates by hybridization. The specificity (ratio of positive results obtained in both methods and the sensitivity (the minimum amount of sample DNA and the labeled probe required for the tests were evaluated.

  18. Exploring the possibilities of capacitively coupled contactless conductivity detection in combination with liquid chromatography for the analysis of polar compounds using aminoglycosides as test case.

    Science.gov (United States)

    Jankovics, Péter; Chopra, Shruti; El-Attug, Mohamed N; Cabooter, Deirdre; Wolfs, Kris; Noszál, Béla; Van Schepdael, Ann; Adams, Erwin

    2015-08-10

    The analysis of highly polar (often charged) compounds which lack a strong UV absorbing chromophore is really challenging. Despite the numerous analytical methods published, the demand for a simple, robust and cheap technique for their analysis still persists. Here, reversed phase (RP) liquid chromatography (LC) with capacitively coupled contactless conductivity detection (C(4)D) was explored for the first time as a possible method for separation and detection of various aminoglycoside (AMG) antibiotics which were taken as typical test compounds: tobramycin (TOB), spectinomycin, streptomycin, amikacin, kanamycin A and kanamycin B. C(4)D was performed using a commercially available as well as a laboratory made cell. As ion-pairing reagents (IPR) four perfluorinated carboxylic acids were used: pentafluoropropionic acid, heptafluorobutyric acid, nonafluoropentanoic acid (NFPA) and pentadecafluorooctanoic acid (PDFOA). 0.125 mM NFPA-acetonitrile (ACN) (90:10) or 0.125 mM PDFOA-ACN (70:30) as mobile phases were suitable to detect TOB with reasonable retention times. However, NFPA was preferred for practical reasons. Its applicable concentration range in the mobile phase was strongly restricted by loss of chromatographic performance at lower levels and excessive background conductivity at higher levels. Overall repeatability and robustness of the method were rather poor which was explained by the relatively low IPR levels. Selectivity between the tested AMGs was mainly influenced by the number of protonated amino groups per molecule making it impossible to separate compounds of equal net charges. Problems encountered with gradient elution, hydrophilic interaction liquid chromatography (HILIC) and separation at high pH without IPRs are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. 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.

  20. Heterologous production of kasugamycin, an aminoglycoside antibiotic from Streptomyces kasugaensis, in Streptomyces lividans and Rhodococcus erythropolis L-88 by constitutive expression of the biosynthetic gene cluster.

    Science.gov (United States)

    Kasuga, Kano; Sasaki, Akira; Matsuo, Takashi; Yamamoto, Chika; Minato, Yuiko; Kuwahara, Naoya; Fujii, Chikako; Kobayashi, Masayuki; Agematu, Hitosi; Tamura, Tomohiro; Komatsu, Mamoru; Ishikawa, Jun; Ikeda, Haruo; Kojima, Ikuo

    2017-05-01

    Kasugamycin (KSM), an aminoglycoside antibiotic isolated from Streptomyces kasugaensis cultures, has been used against rice blast disease for more than 50 years. We cloned the KSM biosynthetic gene (KBG) cluster from S. kasugaensis MB273-C4 and constructed three KBG cassettes (i.e., cassettes I-III) to enable heterologous production of KSM in many actinomycetes by constitutive expression of KBGs. Cassette I comprised all putative transcriptional units in the cluster, but it was placed under the control of the P neo promoter from Tn5. It was not maintained stably in Streptomyces lividans and did not transform Rhodococcus erythropolis. Cassette II retained the original arrangement of KBGs, except that the promoter of kasT, the specific activator gene for KBG, was replaced with P rpsJ , the constitutive promoter of rpsJ from Streptomyces avermitilis. To enhance the intracellular concentration of myo-inositol, an expression cassette of ino1 encoding the inositol-1-phosphate synthase from S. avermitilis was inserted into cassette II to generate cassette III. These two cassettes showed stable maintenance in S. lividans and R. erythropolis to produce KSM. Particularly, the transformants of S. lividans induced KSM production up to the same levels as those produced by S. kasugaensis. Furthermore, cassette III induced more KSM accumulation than cassette II in R. erythropolis, suggesting an exogenous supply of myo-inositol by the ino1 expression in the host. Cassettes II and III appear to be useful for heterologous KSM production in actinomycetes. Rhodococcus exhibiting a spherical form in liquid cultivation is also a promising heterologous host for antibiotic fermentation.

  1. Potentiation of Aminoglycoside Activity in Pseudomonas aeruginosa by Targeting the AmgRS Envelope Stress-Responsive Two-Component System.

    Science.gov (United States)

    Poole, Keith; Gilmour, Christie; Farha, Maya A; Mullen, Erin; Lau, Calvin Ho-Fung; Brown, Eric D

    2016-06-01

    A screen for agents that potentiated the activity of paromomycin (PAR), a 4,5-linked aminoglycoside (AG), against wild-type Pseudomonas aeruginosa identified the RNA polymerase inhibitor rifampin (RIF). RIF potentiated additional 4,5-linked AGs, such as neomycin and ribostamycin, but not the clinically important 4,6-linked AGs amikacin and gentamicin. Potentiation was absent in a mutant lacking the AmgRS envelope stress response two-component system (TCS), which protects the organism from AG-generated membrane-damaging aberrant polypeptides and, thus, promotes AG resistance, an indication that RIF was acting via this TCS in potentiating 4,5-linked AG activity. Potentiation was also absent in a RIF-resistant RNA polymerase mutant, consistent with its potentiation of AG activity being dependent on RNA polymerase perturbation. PAR-inducible expression of the AmgRS-dependent genes htpX and yccA was reduced by RIF, suggesting that AG activation of this TCS was compromised by this agent. Still, RIF did not compromise the membrane-protective activity of AmgRS, an indication that it impacted some other function of this TCS. RIF potentiated the activities of 4,5-linked AGs against several AG-resistant clinical isolates, in two cases also potentiating the activity of the 4,6-linked AGs. These cases were, in one instance, explained by an observed AmgRS-dependent expression of the MexXY multidrug efflux system, which accommodates a range of AGs, with RIF targeting of AmgRS undermining mexXY expression and its promotion of resistance to 4,5- and 4,6-linked AGs. Given this link between AmgRS, MexXY expression, and pan-AG resistance in P. aeruginosa, RIF might be a useful adjuvant in the AG treatment of P. aeruginosa infections. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  2. Beneficial antimicrobial effect of the addition of an aminoglycoside to a β-lactam antibiotic in an E. coli porcine intensive care severe sepsis model.

    Science.gov (United States)

    Skorup, Paul; Maudsdotter, Lisa; Lipcsey, Miklós; Castegren, Markus; Larsson, Anders; Jonsson, Ann-Beth; Sjölin, Jan

    2014-01-01

    This study aimed to determine whether the addition of an aminoglycoside to a ß-lactam antibiotic increases the antimicrobial effect during the early phase of Gram-negative severe sepsis/septic shock. A porcine model was selected that considered each animal's individual blood bactericidal capacity. Escherichia coli, susceptible to both antibiotics, was given to healthy pigs intravenously during 3 h. At 2 h, the animals were randomized to a 20-min infusion with either cefuroxime alone (n = 9), a combination of cefuroxime+tobramycin (n = 9), or saline (control, n = 9). Blood samples were collected hourly for cultures and quantitative polymerase chain reaction (PCR). Bacterial growth in the organs after 6 h was chosen as the primary endpoint. A blood sample was obtained at baseline before start of bacterial infusion for ex vivo investigation of the blood bactericidal capacity. At 1 h after the administration of the antibiotics, a second blood sample was taken for ex vivo investigation of the antibiotic-induced blood killing activity. All animals developed severe sepsis/septic shock. Blood cultures and PCR rapidly became negative after completed bacterial infusion. Antibiotic-induced blood killing activity was significantly greater in the combination group than in the cefuroxime group (pantibiotic groups compared with the controls (pantibiotic groups. Bacterial growth in the liver was significantly less in the combination group than in the cefuroxime group (pantibiotic-induced blood killing activity and less bacteria in the liver than cefuroxime alone. Individual blood bactericidal capacity may have a significant effect on antimicrobial outcome.

  3. 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.

  4. 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

  5. Structure of the bifunctional aminoglycoside-resistance enzyme AAC(6′)-Ie-APH(2′′)-Ia revealed by crystallographic and small-angle X-ray scattering analysis

    Science.gov (United States)

    Smith, Clyde A.; Toth, Marta; Weiss, Thomas M.; Frase, Hilary; Vakulenko, Sergei B.

    2014-01-01

    Broad-spectrum resistance to aminoglycoside antibiotics in clinically important Gram-positive staphylococcal and entero­coccal pathogens is primarily conferred by the bifunctional enzyme AAC(6′)-Ie-APH(2′′)-Ia. This enzyme possesses an N-terminal coenzyme A-dependent acetyltransferase domain [AAC(6′)-Ie] and a C-terminal GTP-dependent phosphotransferase domain [APH(2′′)-Ia], and together they produce resistance to almost all known aminoglycosides in clinical use. Despite considerable effort over the last two or more decades, structural details of AAC(6′)-Ie-APH(2′′)-Ia have remained elusive. In a recent breakthrough, the structure of the isolated C-terminal APH(2′′)-Ia enzyme was determined as the binary Mg2GDP complex. Here, the high-resolution structure of the N-terminal AAC(6′)-Ie enzyme is reported as a ternary kanamycin/coenzyme A abortive complex. The structure of the full-length bifunctional enzyme has subsequently been elucidated based upon small-angle X-ray scattering data using the two crystallographic models. The AAC(6′)-Ie enzyme is joined to APH(2′′)-Ia by a short, predominantly rigid linker at the N-terminal end of a long α-helix. This α-helix is in turn intrinsically associated with the N-terminus of APH(2′′)-Ia. This structural arrangement supports earlier observations that the presence of the intact α-helix is essential to the activity of both functionalities of the full-length AAC(6′)-Ie-APH(2′′)-Ia enzyme. PMID:25286858

  6. Risk factors for colonization with ampicillin and high-level aminoglycoside-resistant enterococci during hospitalization in the ICU and the impact of prior antimicrobial exposure definition: a prospective cohort study.

    Science.gov (United States)

    Srovin, Tina Plankar; Seme, Katja; Blagus, Rok; Tomazin, Rok; Cižman, Milan

    2014-02-01

    The aim of our prospective cohort study was to determine the incidence, genetic relatedness and risk factors for colonization with ampicillin and high-level aminoglycoside-resistant enterococci (ARHLARE) among patients hospitalized in the intensive care unit. During 15-month period, we included 105 patients. The only independent risk factor for ARHLARE colonization was days of cefotaxime/ceftriaxone therapy [odds ratio (OR): 1.13; 95% confidence interval (CI) 1.10-1.27; P  =  0.045]. Patients with higher total use of antibiotics, patients on prolonged mechanical ventilation, and patients with urinary tract infection (UTI), were also found to be at increased risk to become colonized with ARHLARE. Pulsed-field gel electrophoresis suggested multifocal origin of the majority of the colonizing strains. Our results show that an increase in total antibiotic consumption for 10 defined daily doses (DDD)/patient increased the odds of colonization with ARHLARE for 36%. Further efforts to optimize antimicrobial use in high risk patients are proposed.

  7. Aminoglycoside induced ototoxicity associated with mitochondrial ...

    African Journals Online (AJOL)

    Joseph Foster II

    2016-06-16

    Jun 16, 2016 ... one such modifier, as a missense mutation in TRMU was shown to compromise tRNA metabolism. Reduction of tRNA metabolism in combination with the reduction of accurate pro- tein synthesis ..... A limited number of studies have characterized variations .... Genetic analysis of interactions with eukaryotic.

  8. Preventing Ototoxic Synergy of Prior Noise Trauma during Aminoglycoside Therapy

    Science.gov (United States)

    2017-06-01

    Hongzhe Li, PhD CONTRACTING ORGANIZATION: Loma Linda Veterans Association for Research and Education Redlands, CA 92373-5181 REPORT DATE: June...Veterans Association for Research and Education Redlands, CA 92373-5181 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR...interest and motivation in biomedicine research, including college students and international physicians. For instance, Brandon Yeoh, a college

  9. Short-course aminoglycoside therapy in patients with spinal cord injury. Standard dose versus low dose.

    Science.gov (United States)

    Sapico, F L; Lindquist, L B; Montgomerie, J Z; Jimenez, E M; Morrow, J W

    1980-05-01

    Twenty-nine patients with spinal cord injury and asymptomatic urinary tract infection were treated with standard or reduced doses of tobramycin and amikacin. The patients received five days of intramuscular antibiotics. Most of the patients in the tobramycin groups had Pseudomonas aeruginosa infection and most of those in the amikacin group had either Proteus rettgeri or Providencia stuartii infections. Only 1 patient had a positive urine antibody coating test. High antibiotic concentrations were demonstrated in the urine of all patients during therapy. Urine cultures were obtained two and seven days after completion of therapy. Forty-eight per cent of the patients were cured, while 31 per cent showed persistence or relapse, and 21 per cent had reinfection with other bacteria. No significant differences in results were observed between the standard-dose and low-dose regimens and between the amikacin and tobramycin groups. The low success rate of the regimens used may indicate the need to evaluate alternative therapeutic regimens to treat urinary tract infections in this special group of patients.

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

    Directory of Open Access Journals (Sweden)

    Valeria Contreras

    2016-03-01

    Full Text Available En pacientes con cáncer que se presentan con neutropenia febril existe controversia sobre si es mejor utilizar una combinación de antibióticos betalactámicos y aminoglicósidos o si bastaría la monoterapia con betalactámicos de amplio espectro como tratamiento empírico inicial. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en 30 bases de datos, identificamos tres revisiones sistemáticas que en conjunto incluyen 14 estudios aleatorizados pertinentes a esta pregunta. Realizamos un metanálisis y tablas de resumen de los resultados utilizando el método GRADE. Concluimos que adicionar aminoglicósidos a los betalactámicos en el tratamiento de la neutropenia febril en pacientes con cáncer aumenta la nefrotoxicidad y podría aumentar la mortalidad en comparación con la monoterapia con betalactámicos.

  11. Constants of acid‒base equilibria in an aqueous amikacin aminoglycoside solution at 298 K

    Science.gov (United States)

    Alekseev, V. G.; Markova, E. V.

    2016-03-01

    The acid dissociation constants of form p K 1 = 7.34 ± 0.01, p K 2 = 7.84 ± 0.01, p K 3 = 8.77 ± 0.01, p K 4 = 9.49 ± 0.01, and p K 5 = 10.70 ± 0.02 of cationic amikacin are determined by pH-metric titration at 25°C against the background of 0.1 mol/L KNO3. K 1, K 2, K 3, and K 4 correspond to the dissociation of protons coordinated to amino groups, while K 5 characterizes the dissociation of the hydroxyl hydrogen atom, testifying to the amphoteric character of amikacin molecules. Applying density functional theory (DFT) with the B3LYP hybrid functional and the 6-311G**++ basis set, the partial charges on the atoms of an amikacin molecule are calculated. It is concluded that the dissociation of H(55)hydrogen atom occurs with a greatest partial charge of +0.53631.

  12. Indigenous and acquired modifications in the aminoglycoside binding sites of Pseudomonas aeruginosa rRNAs

    DEFF Research Database (Denmark)

    Gutierrez, Belen; Douthwaite, Stephen Roger; Gonzalez-Zorn, Bruno

    2013-01-01

    (housekeeping) modifications at m (4)Cm1402, m (3)U1498, m (2)G1516, m (6) 2A1518, and m (6) 2A1519; helix 69 is modified at m (3)Ψ1915, with m (5)U1939 and m (5)C1962 modification in adjacent sequences. All modifications were close to stoichiometric, with the exception of m (3)Ψ1915, where about 80% of r...

  13. Alanine Enhances Aminoglycosides-Induced ROS Production as Revealed by Proteomic Analysis

    Directory of Open Access Journals (Sweden)

    Jin-zhou Ye

    2018-01-01

    Full Text Available Metabolite-enabled killing of antibiotic-resistant pathogens by antibiotics is an attractive strategy to manage antibiotic resistance. Our previous study demonstrated that alanine or/and glucose increased the killing efficacy of kanamycin on antibiotic-resistant bacteria, whose action is through up-regulating TCA cycle, increasing proton motive force and enhancing antibiotic uptake. Despite the fact that alanine altered several metabolic pathways, other mechanisms could be potentially involved in alanine-mediated kanamycin killing of bacteria which remains to be explored. In the present study, we adopted proteomic approach to analyze the proteome changes induced by exogenous alanine. Our results revealed that the expression of three outer membrane proteins was altered and the deletion of nagE and fadL decreased the intracellular kanamycin concentration, implying their possible roles in mediating kanamycin transport. More importantly, the integrated analysis of proteomic and metabolomic data pointed out that alanine metabolism could connect to riboflavin metabolism that provides the source for reactive oxygen species (ROS production. Functional studies confirmed that alanine treatment together with kanamycin could promote ROS production that in turn potentiates the killing of antibiotic-resistant bacteria. Further investigation showed that alanine repressed the transcription of antioxidant-encoding genes, and alanine metabolism to riboflavin metabolism connected with riboflavin metabolism through TCA cycle, glucogenesis pathway and pentose phosphate pathway. Our results suggest a novel mechanism by which alanine facilitates kanamycin killing of antibiotic-resistant bacteria via promoting ROS production.

  14. Purification and Characterization of Aminoglycoside Phosphotransferase APH(6)-Id, a Streptomycin Inactivating Enzyme

    Science.gov (United States)

    Ashenafi, Meseret; Ammosova, Tatiana; Nekhai, Sergei; Byrnes, W. Malcolm

    2014-01-01

    As part of an overall project to characterize the streptomycin phosphotransferase enzyme APH(6)-Id, which confers bacterial resistance to streptomycin, we cloned, expressed, purified and characterized the enzyme. When expressed in E. coli, the recombinant enzyme increased by up to 70-fold the minimum inhibitory concentration (MIC) needed to inhibit cell growth. Size exclusion chromatography gave a molecular mass of 31.4 ± 1.3 kDa for the enzyme, showing that it functions as a monomer. Activity was assayed using three methods: (1) an HPLC-based method that measures the consumption of streptomycin over time; (2) a spectrophotometric method that utilizes a coupled assay; and (3) a radioenzymatic method that detects production of 32P-labeled streptomycin phosphate. Altogether, the three methods demonstrated that streptomycin was consumed in the APH(6)-Id-catalyzed reaction, ATP was hydrolyzed, and streptomycin phosphate was produced in a substrate-dependent manner, demonstrating that APH(6)-Id is a streptomycin phosphotransferase. Steady state kinetic analysis gave the following results: Km(streptomycin) of 0.38 ± 0.13 mM, Km(ATP) of 1.03 ± 0.1 mM, Vmax of 3.2 ± 1.1 μmol/min/mg and kcat of 1.7 ± 0.6 s−1. Our study demonstrates that APH(6)-Id is a bona fide streptomycin phosphotransferase, functions as a monomer, and confers resistance to streptomycin. PMID:24248535

  15. New Integron-Associated Gene Cassette Encoding a 3-N-Aminoglycoside Acetyltransferase

    OpenAIRE

    Levings, Renee S.; Partridge, Sally R.; Lightfoot, Diane; Hall, Ruth M.; Djordjevic, Steven P.

    2005-01-01

    A fifth gene cassette containing an aacC gene, aacCA5, was found in an aacCA5-aadA7 cassette array in a class 1 integron isolated from a multiply drug resistant Salmonella enterica serovar Kentucky strain. The AacC-A5 or AAC(3)-Ie acetyltransferase encoded by aacCA5 is related to other AAC(3)-I enzymes and confers resistance to gentamicin.

  16. Aminoglycosides Monotherapy as First-Line Treatment for Febrile Urinary Tract Infection in Children.

    Science.gov (United States)

    Poey, Nora; Madhi, Fouad; Biscardi, Sandra; Béchet, Stéphane; Cohen, Robert

    2017-11-01

    We report a retrospective monocentric descriptive study performed in CHI Creteil for 20 months to describe the management and outcome of amikacin monotherapy as an alternative to third-generation cephalosporins for empiric treatment of febrile urinary tract infection (FUTI) in children. Data were analyzed for 151 children, and 90 selected cases were classified as certain or highly probable FUTI. Escherichia coli infection was found in 89 cases. In all patients, fever was resolved within 72 hours after beginning amikacin treatment. Only 5.3% of children were febrile after 48 hours. The mean amikacin treatment duration was 3.05 ± 0.13 days before oral treatment began (guided by antibiotic susceptibility testing). Amikacin monotherapy seems effective for the initial management of FUTI in children.

  17. Multiple paths towards reduced membrane potential and concomitant reduction in aminoglycoside susceptibility in staphylococcus aureus

    DEFF Research Database (Denmark)

    Vestergaard, Martin; Nøhr-Meldgaard, Katrine; Ingmer, Hanne

    2018-01-01

    the largest increase in gentamicin susceptibility and exhibited a small colony variant phenotype, whereas the remaining mutants (qoxA, qoxB, qoxC, ndh and hemX) displayed colony morphology similar to the wild type. All of the mutants, except hemX, displayed reduced membrane potential suggesting that reduced...

  18. 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

    . The purpose of the present study was to determine if sublethal biocide concentrations affected antibiotic susceptibility in L. monocytogenes. Exposure of L. monocytogenes strains EGD and N53-1 to sublethal concentrations of Incimaxx DES (containing peroxy acids and hydrogen peroxide) and Triquart Super......The human food-borne pathogen Listeria monocytogenes is capable of persisting in food processing plants despite cleaning and sanitation and is likely exposed to sublethal biocide concentrations. This could potentially affect susceptibility of the bacterium to biocides and other antimicrobial agents...... (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...

  19. Putrescine controls the formation of Escherichia coli persister cells tolerant to aminoglycoside netilmicin.

    Science.gov (United States)

    Tkachenko, Alexander G; Kashevarova, Natalya M; Karavaeva, Elena A; Shumkov, Mikhail S

    2014-12-01

    Persisters are suggested to be the products of a phenotypic variability that are quasi-dormant forms of regular bacterial cells highly tolerant to antibiotics. Our previous investigations revealed that a decrease in antibiotic tolerance of Escherichia coli cells could be reached through the inhibition of key enzymes of polyamine synthesis (putrescine, spermidine). We therefore assumed that polyamines could be involved in persister cell formation. Data obtained in our experiments with the polyamine-deficient E. coli strain demonstrate that the formation of persisters tolerant to netilmicin is highly upregulated by putrescine in a concentration-dependent manner when cells enter the stationary phase. This period is also accompanied by dissociation of initially homogenous subpopulation of persister cells to some fractions differing in their levels of tolerance to netilmicin. With three independent experimental approaches, we demonstrate that putrescine-dependent upregulation of persister cell formation is mediated by stimulation of rpoS expression. Complementary activity of putrescine and RpoS results in ~ 1000-fold positive effect on persister cell formation. © 2014 Federation of European Microbiological Societies.

  20. Tolerance of Norway spruce (Picea abies [L.] Karst.) embryogenic tissue to penicillin, carbapenem and aminoglycoside antibiotics

    Czech Academy of Sciences Publication Activity Database

    Malá, J.; Pavingerová, Daniela; Cvrčková, H.; Bříza, Jindřich; Dostál, J.; Šíma, P.

    2009-01-01

    Roč. 55, č. 4 (2009), s. 156-161 ISSN 1212-4834 R&D Projects: GA MZe QH71290 Institutional research plan: CEZ:AV0Z50510513 Keywords : somatic embryogenesis * Norway spruce * penicillin antibiotics * Agrobacterium tumefaciens * carbapenem antibiotics Subject RIV: EB - Genetics ; Molecular Biology

  1. Spectrophotometric Determination of Aminoglycoside Antibiotics Based on their Oxidation by Potassium Permanganate

    International Nuclear Information System (INIS)

    El-Didamony, A. M.; Ghoneim, A. K.; Telebany, A. M.; Amin, A. S.

    2006-01-01

    A rapid, simple and sensitive validated spectrophotometric methods have been described for the assay of neomycin and streptomycin either in pure form or in pharmaceutical formulations. The proposed methods were based on the oxidation of the studied drugs by a known excess of potassium permanganate in acidic medium and estimating the unreacted permanganate with amaranth dye (method A), acid orange II (method B), indigocarmine (method C), and methylene blue (method D), in the same acid medium at a suitable λ max =521, 485, 610 and 664 nm, respectively. Beer's law is obeyed in the concentration range of 5-10 and 2-7 mg mL -1 for neomycin and streptomycin, respectively. The apparent molar absorptivity and sandell sensitivity values are in the range 5.47-6.20x10 4 , 2.35-2.91x10 5 L mol -1 cm -1 and 7.57-8.59, 5.01-6.2 ng cm -2 for neomycin and streptomycin, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs either in a pure or pharmaceutical dosage forms with good accuracy and precision. No interferences were observed from excipients and the results obtained were in good agreement with those obtained using the official methods

  2. Evaluation of Antibacterial Activity of Aminoglycosides and Modulating the Essential Oil of Cymbopogon citratus (DC. Stapf

    Directory of Open Access Journals (Sweden)

    Saulo R. TINTINO

    2015-01-01

    Vários trabalhos vêm demonstrando a importância do estudo de produtos naturais como fonte alternativa para novos antimicrobianos ou que venham potencializar os já existentes. Neste contexto este trabalho teve como objetivo investigar a atividade antibacteriana e as possíveis interações entre o óleo essencial de Cymbopogon citratus combinados a aminoglicosídeos frente a linhagens padrões e multirresistentes de S. aureus, E. coli e de P. aeruginosa provenientes de isolados clínicos. Um ensaio de microdiluição foi realizado para verificar a atividade antibacteriana e as possíveis interacções entre o produto natural e os antibióticos, utilizando uma concentração sub-inibitória. Através dos resultados foi constatado a interferência sinérgica dos aminoglicosídeos quando associados com o óleo essencial em uma concentração de CIM/8, com redução das CIMs em até quatro pontos frente às linhagens de S. aureus 358, E. coli 27 e P. aeruginosa-143. Mas nenhuma atividade modificadora foi observada frente a P. aeruginosa 78 e P. aeruginosa 91. Através dos resultados pode-se concluir que o óleo essencial de Cymbopogon citratus pode ser uma fonte alternativa de produtos naturais com atividade antibacteriana. Vários trabalhos vêm demonstrando a importância do estudo de produtos naturais como fonte alternativa para novos antimicrobianos ou que venham potencializar os já existentes. Neste contexto este trabalho teve como objetivo investigar a atividade antibacteriana e as possíveis interações entre o óleo essencial de Cymbopogon citratus combinados a aminoglicosídeos frente a linhagens padrões e multirresistentes de S. aureus, E. coli e de P. aeruginosa provenientes de isolados clínicos. Um ensaio de microdiluição foi realizado para verificar a atividade antibacteriana e as possíveis interacções entre o produto natural e os antibióticos, utilizando uma concentração sub-inibitória. Através  dos resultados foi constatado a interferência sinérgica  dos aminoglicosídeos quando associados com o óleo essencial em uma concentração de CIM/8, com redução das CIMs em  até quatro pontos frente  às linhagens de S. aureus 358, E. coli 27 e P. aeruginosa-143. Mas nenhuma atividade modificadora foi observada frente a P. aeruginosa 78 e P. aeruginosa 91. Através dos resultados pode-se concluir que o óleo essencial de Cymbopogon citratus pode ser uma fonte alternativa de produtos naturais com atividade antibacteriana.

  3. Purification and Characterization of Aminoglycoside Phosphotransferase APH(6)-Id, a Streptomycin Inactivating Enzyme

    OpenAIRE

    Ashenafi, Meseret; Ammosova, Tatiana; Nekhai, Sergei; Byrnes, W. Malcolm

    2013-01-01

    As part of an overall project to characterize the streptomycin phosphotransferase enzyme APH(6)-Id, which confers bacterial resistance to streptomycin, we cloned, expressed, purified and characterized the enzyme. When expressed in E. coli, the recombinant enzyme increased by up to 70-fold the minimum inhibitory concentration (MIC) needed to inhibit cell growth. Size exclusion chromatography gave a molecular mass of 31.4 ± 1.3 kDa for the enzyme, showing that it functions as a monomer. Activit...

  4. Purification and characterization of aminoglycoside phosphotransferase APH(6)-Id, a streptomycin-inactivating enzyme.

    Science.gov (United States)

    Ashenafi, Meseret; Ammosova, Tatiana; Nekhai, Sergei; Byrnes, W Malcolm

    2014-02-01

    As part of an overall project to characterize the streptomycin phosphotransferase enzyme APH(6)-Id, which confers bacterial resistance to streptomycin, we cloned, expressed, purified, and characterized the enzyme. When expressed in Escherichia coli, the recombinant enzyme increased by up to 70-fold the minimum inhibitory concentration needed to inhibit cell growth. Size-exclusion chromatography gave a molecular mass of 31.4 ± 1.3 kDa for the enzyme, showing that it functions as a monomer. Activity was assayed using three methods: (1) an HPLC-based method that measures the consumption of streptomycin over time; (2) a spectrophotometric method that utilizes a coupled assay; and (3) a radioenzymatic method that detects production of (32)P-labeled streptomycin phosphate. Altogether, the three methods demonstrated that streptomycin was consumed in the APH(6)-Id-catalyzed reaction, ATP was hydrolyzed, and streptomycin phosphate was produced in a substrate-dependent manner, demonstrating that APH(6)-Id is a streptomycin phosphotransferase. Steady-state kinetic analysis gave the following results: K(m)(streptomycin) of 0.38 ± 0.13 mM, K(m)(ATP) of 1.03 ± 0.1 mM, V(max) of 3.2 ± 1.1 μmol/min/mg, and k(cat) of 1.7 ± 0.6 s(-1). Our study demonstrates that APH(6)-Id is a bona fide streptomycin phosphotransferase, functions as a monomer, and confers resistance to streptomycin.

  5. EPR studies of free radicals decay and survival in gamma irradiated aminoglycoside antibiotics: sisomicin, tobramycin and paromomycin.

    Science.gov (United States)

    Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

    2012-02-14

    Radiation sterilization technology is more actively used now that any time because of its many advantages. Gamma radiation has high penetrating power, relatively low chemical reactivity and causes small temperature rise. But on the other hand radiosterilization can lead to radiolytic products appearing, in example free radicals. Free radicals in radiative sterilized sisomicin, tobramycin and paromomycin were studied by electron paramagnetic resonance (EPR) spectroscopy. Dose of gamma irradiation of 25kGy was used. Concentrations and properties of free radicals in irradiated antibiotics were studied. EPR spectra were recorded for samples stored in air and argon. For gamma irradiated antibiotics strong EPR lines were recorded. One- and two-exponential functions were fitted to experimental points during testing and researching of time influence of the antibiotics storage to studied parameters of EPR lines. Our study of free radicals in radiosterilized antibiotics indicates the need for characterization of medicinal substances prior to sterilization process using EPR values. We propose the concentration of free radicals and other spectroscopic parameters as useful factors to select the optimal type of sterilization for the individual drug. The important parameters are i.a. the τ time constants and K constants of exponential functions. Time constants τ give us information about the speed of free radicals concentration decrease in radiated medicinal substances. The constant K(0) shows the free radicals concentration in irradiated medicament after long time of storage. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Reduced Chance of Hearing Loss Associated with Therapeutic Drug Monitoring of Aminoglycosides in the Treatment of Multidrug-Resistant Tuberculosis

    NARCIS (Netherlands)

    Altena, R. van; Dijkstra, J.A.; Meer, M.E. van der; Howard, J.F.B.; Kosterink, J.G.W.; Soolingen, D. van; Werf, T.S. van der; Alffenaar, J.W.C.

    2017-01-01

    Hearing loss and nephrotoxicity are associated with prolonged treatment duration and higher dosage of amikacin and kanamycin. In our tuberculosis center, we used therapeutic drug monitoring (TDM) targeting preset pharmacokinetic/pharmacodynamic (PK/PD) surrogate endpoints in an attempt to maintain

  7. Reduced chance of hearing loss associated with Therapeutic Drug Monitoring of Aminoglycosides in the treatment of Multidrug Resistant Tuberculosis

    NARCIS (Netherlands)

    van Altena, R; Dijkstra, J.A.; van der Meer, M E; Borjas Howard, J F; Kosterink, J G W; van Soolingen, D; van der Werf, T S; Alffenaar, J W C

    Hearing loss and nephrotoxicity are associated with prolonged treatment duration and higher dosage of amikacin and kanamycin. In our Tuberculosis Center, we have employed therapeutic drug monitoring (TDM) targeting pre-set pharmacokinetic/pharmacodynamic (PK/PD) surrogate endpoints in an attempt to

  8. 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

    of universally conserved nucleotides at 1406 to 1408 and 1494 to 1495 in the decoding region of plasmid-encoded bacterial 16 S rRNA. Phenotypic changes range from the benign effect of U1406-->A or A1408-->G substitutions, to the highly deleterious 1406G and 1495 mutations that assemble into 30 S subunits...

  9. Study of the aminoglycoside subsistence phenotype of bacteria residing in the gut of humans and zoo animals

    NARCIS (Netherlands)

    Bello Gonzalez, Teresita; Zuidema, Tina; Bor, Gerrit; Smidt, Hauke; Passel, van M.W.J.

    2016-01-01

    Recent studies indicate that next to antibiotic resistance, bacteria are able to subsist on antibiotics as a carbon source. Here we evaluated the potential of gut bacteria from healthy human volunteers and zoo animals to subsist on antibiotics. Nine gut isolates of Escherichia coli and

  10. High Prevalence and Predominance of the aph(2″)-If Gene Conferring Aminoglycoside Resistance in Campylobacter

    OpenAIRE

    Yao, Hong; Liu, Dejun; Wang, Yang; Zhang, Qijing; Shen, Zhangqi

    2017-01-01

    Campylobacter is a major foodborne pathogen, and previous studies revealed that Campylobacter isolates from food-producing animals are increasingly resistant to gentamicin in China. The molecular epidemiology and genetic mechanisms responsible for gentamicin resistance in China have not been well understood. In this study, 607 Campylobacter isolates of chicken and swine origins collected in 2014 were analyzed, revealing that 15.6% (25/160) of the Campylobacter jejuni isolates and 79.9% (357/4...

  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...

  12. Outbreak of Serratia marcescens Coproducing ArmA and CTX-M-15 Mediated High Levels of Resistance to Aminoglycoside and Extended-Spectrum Beta-Lactamases, Algeria.

    Science.gov (United States)

    Batah, Rima; Loucif, Lotfi; Olaitan, Abiola Olumuyiwa; Boutefnouchet, Nafissa; Allag, Hamoudi; Rolain, Jean-Marc

    2015-08-01

    Serratia marcescens is one of the most important pathogens responsible for nosocomial infections worldwide. Here, we have investigated the molecular support of antibiotic resistance and genetic relationships in a series of 54 S. marcescens clinical isolates collected from Eastern Algeria between December 2011 and July 2013. The 54 isolates were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Antibiotic susceptibility testing was performed by disc diffusion and E-test methods. Antibiotic resistance genes were detected by polymerase chain reaction (PCR). The genetic transfer of antibiotic resistance was performed by conjugation using azide-resistant Escherichia coli J53 as the recipient strain, and plasmid analysis was done by PCR-based replicon typing. The relatedness of our isolates was determined by phylogenetic analysis based on partial sequences of four protein-encoding genes (gyrB, rpoB, infB, and atpD) and then compared to MALDI-TOF MS clustering. Thirty-five out of 54 isolates yielded an extended-spectrum β-lactamase (ESBL) phenotype and carried bla(CTX-M-15) (n=32), bla(TEM-1) (n=26), bla(TEM-71) (n=1), bla(SHV-1a) (n=1), and bla(PER-2) (n=12). Among these isolates, we identified a cluster of 15 isolates from a urology unit that coharbored ESBL and the 16S rRNA methyltransferase armA. Conjugation was successful for five selected strains, demonstrating the transferability of a conjugative plasmid of incompatibility group incL/M type. Phylogenetic analysis along with MALDI-TOF clustering likely suggested an outbreak of such isolates in the urology unit. In this study, we report for the first time the co-occurrence of armA methyltransferase with ESBL in S. marcescens clinical isolates in Eastern Algeria.

  13. Pasteurellaceae bacteria from the oral cavity of Tasmanian devils (Sarcophilus Harrisii) show high minimum inhibitory concentration values towards aminoglycosides and clindamycin

    DEFF Research Database (Denmark)

    Gutman, N.; Hansen, Mie Johanne; Bertelsen, M. F.

    2016-01-01

    of the oral microbiota. In medical management of such bite wounds, antimicrobial susceptibility profiles are crucial. Prior to this investigation, no available data on minimal inhibitory concentration (MIC) values existed. A total of 26 isolates obtained from the oral cavity of 26 healthy Tasmanian devils...... for antimicrobial therapy against bite wound infections caused by Pasteurellaceae originating from the oral cavity of Tasmanian devils....

  14. Cholera in Vietnam: Changes in Genotypes and Emergence of Class I Integrons Containing Aminoglycoside Resistance Gene Cassettes in Vibrio cholerae O1 Strains Isolated from 1979 to 1996

    OpenAIRE

    Dalsgaard, A.; Forslund, A.; Tam, N. V.; Vinh, D. X.; Cam, P. D.

    1999-01-01

    The number of cholera cases and the mortality rates reported from different regions of Vietnam varied considerably in the period from 1979 to 1996, with between 2,500 and 6,000 cases reported annually from 1992 to 1995. Annual mortality rates ranged from 2.0 to 9.6% from 1979 to 1983 to less than 1.8% after 1983. Major cholera outbreaks were reported from the High Plateau region for the first time in 1994 and 1995; this is an area with limited access to health services and safe drinking-water...

  15. Cholera in Vietnam: Changes in Genotypes and Emergence of Class I Integrons Containing Aminoglycoside Resistance Gene Cassettes in Vibrio cholerae O1 Strains Isolated from 1979 to 1996

    Science.gov (United States)

    Dalsgaard, A.; Forslund, A.; Tam, N. V.; Vinh, D. X.; Cam, P. D.

    1999-01-01

    The number of cholera cases and the mortality rates reported from different regions of Vietnam varied considerably in the period from 1979 to 1996, with between 2,500 and 6,000 cases reported annually from 1992 to 1995. Annual mortality rates ranged from 2.0 to 9.6% from 1979 to 1983 to less than 1.8% after 1983. Major cholera outbreaks were reported from the High Plateau region for the first time in 1994 and 1995; this is an area with limited access to health services and safe drinking-water supplies. All cases were associated with Vibrio cholerae O1. Using ribotyping, cholera toxin (CT) genotyping, and characterization of antibiotic susceptibility patterns and antibiotic resistance genes by PCR, we show that strains isolated after 1990 were clearly different from strains isolated before 1991. In contrast to strains isolated before 1991, 94% of 104 strains isolated after 1990 showed an identical ribotype R1, were resistant to sulfamethoxazole and streptomycin, and showed a different CT genotype. Furthermore, PCR analysis revealed that sulfamethoxazole-resistant strains harbored class I integrons containing a gene cassette ant(3")-1a encoding resistance to streptomycin and spectinomycin. This is, to our knowledge, the first report of class I integrons in V. cholerae. The development of cholera and the changes in the phenotypic and genotypic properties of V. cholerae O1 shown in the present study highlight the importance of monitoring V. cholerae O1 in Vietnam as in other parts of the world. In particular, the emergence of the new ribotype R1 strain containing class I integrons should be further studied. PMID:9986842

  16. An usual approach to treatment of a case of multidrug resistance Pseudomonas aeruginosa peritonitis: parenteral and intraperitoneal aminoglycosides and parenteral colistin

    Directory of Open Access Journals (Sweden)

    Ian May

    2012-09-01

    Full Text Available Infections caused by Pseudomonas aeruginosa are becoming more common and increasingly more difficult to treat due to the continued development of drug resistance. While sensitivity to colistin (polymyxin E is well known, it is frequently avoided due to concerns of nephrotoxicity. Reported here is a case of a multi-drug resistance pseudomonal typhlitis, bacteremia and pleural cavity infection that required significant intensive care, and serial abdominal washouts. Intra-peritoneal tobramycin in combination with broad-spectrum intravenous antibiotics including colistin were used. Several instillations of tobramycin into the abdominal cavity along with concomitant IV administration of colistin, ceftazidime and tobramycin and per os colistin, tobramycin and nystatin resulted in the clearance of the pseudomonal infection without any evidence of toxicity from the treatment. Intra-abdominal tobramycin with parenteral colistin therapy can be used in complicated clinical settings with appropriate nephroprotection.

  17. A GC1 Acinetobacter baumannii isolate carrying AbaR3 and the aminoglycoside resistance transposon TnaphA6 in a conjugative plasmid.

    Science.gov (United States)

    Hamidian, Mohammad; Holt, Kathryn E; Pickard, Derek; Dougan, Gordon; Hall, Ruth M

    2014-04-01

    To locate the acquired antibiotic resistance genes, including the amikacin resistance transposon TnaphA6, in the genome of an Australian isolate belonging to Acinetobacter baumannii global clone 1 (GC1). A multiply antibiotic-resistant GC1 isolate harbouring TnaphA6 was sequenced using Illumina HiSeq, and reads were used to generate a de novo assembly and determine multilocus sequence types (STs). PCR was used to assemble the AbaR chromosomal resistance island and a large plasmid carrying TnaphA6. Plasmid DNA sequences were compared with ones available in GenBank. Conjugation experiments were conducted. The A. baumannii GC1 isolate G7 was shown to include the AbaR3 antibiotic resistance island. It also contains an 8.7 kb cryptic plasmid, pAb-G7-1, and a 70,100 bp plasmid, pAb-G7-2, carrying TnaphA6. pAb-G7-2 belongs to the Aci6 Acinetobacter plasmid family. It encodes transfer functions and was shown to conjugate. Plasmids related to pAb-G7-2 were detected in further amikacin-resistant GC1 isolates using PCR. From the genome sequence, isolate G7 was ST1 (Institut Pasteur scheme) and ST231 (Oxford scheme). Using Oxford scheme PCR-based methods, the isolate was ST109 and this difference was traced to a single base difference resulting from the inclusion of the original primers in the gpi segment analysed. The multiply antibiotic-resistant GC1 isolate G7 carries most of its resistance genes in AbaR3 located in the chromosome. However, TnaphA6 is on a conjugative plasmid, pAb-G7-2. Primers developed to locate TnaphA6 in pAb-G7-2 will simplify the detection of plasmids related to pAb-G7-2 in A. baumannii isolates.

  18. NEONATAL SEPTICAEMIA IN LOW BIRTH WEIGHT INFANTS AT ...

    African Journals Online (AJOL)

    2005-03-03

    Mar 3, 2005 ... Antibiotic sensitivity revealed high resistance to ampicillin and good sensitivity to aminoglycosides, third generation cephalosporins, clavulanic acid potentiated amoxycillin ... Antibiotic sensitivity shows adequate sensitivity to aminoglycosides and third .... generation cephalosporins as a first line (routine).

  19. Concomitant gentamicin‑induced nephrotoxicity and bilateral ...

    African Journals Online (AJOL)

    ... injections of gentamicin. Coexisting ototoxicity and nephrotoxicity from aminoglycosides can occur, though rare. Adverse effects of aminoglycosides are better prevented by a careful exercise of discretion by prescribers. Keywords: Acute kidney injury, aminoglycosides, co‑occurrence, gentamicin, nephrotoxicity, ototoxicity ...

  20. Occurence of ArmA and RmtB aminoglycoside resistance 16S rRNA methylases in extended-spectrum β-lactamases producing Escherichia coli in Algerian hospitals.

    Directory of Open Access Journals (Sweden)

    Amel Ayad

    2016-09-01

    Full Text Available The aim of this study was to characterize the extended-spectrum-β-lactamases (ESBLs producing clinical strains of Escherichia coli isolated between January 2009 and June 2012 from Algerian hospitals and to determine the prevalence of 16S rRNA methylase among them. Sixty-seven ESBL-producers were detected among the 239 isolates included: 52 CTX-M-15-producers, 5 CTX-M-3-producers, 5 CTX-M-1-producers, 2 CTX-M-14-producers, 2 SHV-12-producers and one TEM-167-producer. Among the ESBL-producing strains twelve harboured 16S rRNA methylase genes: 8 rmtB and 4 armA. rmtB was located on a IncFIA plasmid and armA was located either on a IncL/M or a IncFIA plasmid. RmtB-producing isolates were genotypically related and belonged to the sequence type ST 405 whereas ArmA-producing isolates belonged to ST10, ST 167 and ST 117. This first description of 16S rRNA methylases among E. coli in Algerian hospitals pointed out the necessity to establish control measures to avoid their dissemination.

  1. 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)

    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 f...

  2. ORF Alignment: NC_002945 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available ] ... pdb|1M4I|B Chain B, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis...ain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex W...se From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Ribostamycin ... pdb|1M4G|A... Chain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis... ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Tob

  3. ORF Alignment: NC_000962 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available ] ... pdb|1M4I|B Chain B, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis...ain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex W...se From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Ribostamycin ... pdb|1M4G|A... Chain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis... ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Tob

  4. ORF Alignment: NC_002755 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available ] ... pdb|1M4I|B Chain B, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis...ain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex W...se From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Ribostamycin ... pdb|1M4G|A... Chain A, Aminoglycoside ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis... ... 2'-N-Acetyltransferase From Mycobacterium ... Tuberculosis-Complex With Coenzyme A And Tob

  5. Metagenomic Sequencing for Detection of Non-Traditional Biological Agents: Synthetic Constructs, Genetically Modified Organisms, and Emerging Threats

    Science.gov (United States)

    2013-03-31

    emb|V 01547.1| Streptococcus faecalis kanamycin resistance gene encoding a 3𔃿’’-aminoglycoside phosphotransferase of type III. The gene resides on...gi|47033|emb|V 01547.1| Streptococcus faecalis kanamycin resistance gene encoding a 3𔃿’’-aminoglycoside phosphotransferase of type III. The gene...0.0009 gi|47033|emb|V 01547.1| Streptococcus faecalis kanamycin resistance gene encoding a 3𔃿’’-aminoglycoside phosphotransferase of type III

  6. Quantitative affinity electrophoresis of RNA-small molecule interactions by cross-linking the ligand to acrylamide.

    Science.gov (United States)

    Boodram, Sherry N; McCann, Lucas C; Organ, Michael G; Johnson, Philip E

    2013-11-15

    We show that the affinity electrophoresis analysis of RNA-small molecule interactions can be made quantifiable by cross-linking the ligand to the gel matrix. Using an RNA-aminoglycoside model system to verify our method, we attached an acryloyl chloride molecule to the aminoglycosides paromomycin and neomycin B to synthesize an acrylamide-aminoglycoside monomer. This molecule was then used as a component in gel polymerization for affinity electrophoresis, covalently attaching an aminoglycoside molecule to the gel matrix. To test RNA binding to the cross-linked aminoglycosides, we used the aminoglycoside binding RNA molecule derived from thymidylate synthase messenger RNA (mRNA) that contains a C-C mismatch. Binding is indicated by the difference in RNA mobility between gels with cross-linked ligand, with ligand embedded during polymerization, and with no ligand present. Critically, the predicted straight line relationship between the reciprocal of the relative migration of the RNA and the ligand concentration is obtained when using cross-linked aminoglycosides, whereas a straight line is not obtained using embedded aminoglycosides. Average apparent dissociation constants are determined from the slope of the line from these plots. This method allows an easy quantitative comparison between different nucleic acid molecules for a small molecule ligand. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Detection of antibiotics residues in meat of reformed and marketed ...

    African Journals Online (AJOL)

    Results showed that farmers use eight families of antibiotics: aminoglycosides, diaminopyridines, macrolides, polypeptides, quinolones second and third generation, sulfonamides and tetracyclines. Residues of tetracyclines and aminoglycosides were found only in Abomey-Calavi town with respective proportions of 25.71 ...

  8. 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.

  9. 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.

  10. Atividade da gama glutamil transpeptidase urinária, dosagens séricas de uréia e creatinina como meios diagnósticos auxiliares na nefrotoxicidade induzida por aminoglicosídeo em cães Urinary gamma glutamyl transpeptidase activity, urinalysis, bun and creatinine serum dosages as a auxiliary diagnostic mean in dogs nephrotoxicity induced by aminoglycosides

    Directory of Open Access Journals (Sweden)

    Carla Rosane de Aguiar Hennemann

    1997-06-01

    Full Text Available Foram utilizados 11 cães, hígidos, com idade entre 1 e 5 anos. Inicialmente procedeu-se à determinação dos valores basais através de cinco colheitas diárias de urina e sangue, e realizou-se a urinálise, determinação da atividade da gama glutamil transpeptidase urinária, dosagens sérica de uréia e creatinina. A nefrotoxicidade foi induzida com a utilização de10mg/kg de gentamicina, 3 vezes ao dia, durante 14 dias. As colheitas de urina foram realizadas a cada 24 hors e o sangue foi colhido a cada 48 horas, durante 14 dias. Após este período os cães foram submetidos à eutanásia, procedendo-se à necropsia, e estudo histopatológico dos rins. Os sinais clínicos apresentados foram apatia, anorexia, poliúria, oligúria, anúria, polidipsia, vômito e diarréia. Pela urinálise observou-se a ocorrência de proteinúria, glicosúria, hematúria, cilindrúria, celulúria e isostenúria; os valores de gama glutamil transpeptidase urinária elevaram-se de forma crescente a partir de 24 horas de administração da gentamicina até o final do experimento, a azotemia foi observada no 12° e 14° dias da pesquisa. Na avaliação histopatológica observou-se nefrose tubular aguda. Com base nos resultados obtidos pode-se concluir que a mensuração da atividade da gama glutamil transpeptidase urinária é um sensível indicador de lesão tubular renal possibilitando o diagnóstico precoce, juntamente com a urinálise.Eleven healthy dogs, ranging from one to five years old, were used for this study. Base line values were determined through five daily samples of urine for urinalysis and urinary gamma glutamyl transpeptidase activity, and blood for serum dosage of BUN and creatinine. Nephrotoxicity was induced using 10mg/kg of gentamicin, 3 times a day (tid, for 14 days. Urine samples were drawn every 24 hours and blood samples every 48 hours, for 14 days. After this period, the dogs were euthanized and necropsy was done for further histopathologic study. The clinical signs shown by the dogs were lethargy, anorexy, polyuria, oliguria, anuria, polydypsia, vomiting and diarrhea. Urinalysis findings were proteinuria, glucosuria, hematuria, cilindruria, celluria and decrease of urinary specific gravity and crescent values of urinary gamma glutamyl transpeptidase from 24 hours after gentamicin administration until the "end of" the experiment. Azotemia was noticed on the 12th and 14th days of the study. Acute tubular nephrosis was established in the histological evaluation. Based on the results found on this study, the measurement of the urinary gamma glutamyl transpeptidase activity might be considered a sensitive indicator of renal tubular damage allowing early diagnosis of the lesion.

  11. N-Acetylcysteine in the prevention of ototoxicity

    DEFF Research Database (Denmark)

    Tepel, Martin

    2007-01-01

    Prevention of ototoxicity after the administration of aminoglycoside antibiotics has been notably difficult, in particular in patients with chronic kidney disease. Feldman et al. report that oral administration of 600 mg N-acetylcysteine twice daily significantly ameliorates gentamicin-induced ot......-induced ototoxicity in hemodialysis patients. That approach may help to prevent aminoglycoside-induced hearing loss in these high-risk patients in daily practice.......Prevention of ototoxicity after the administration of aminoglycoside antibiotics has been notably difficult, in particular in patients with chronic kidney disease. Feldman et al. report that oral administration of 600 mg N-acetylcysteine twice daily significantly ameliorates gentamicin...

  12. Short- and long-term influences of heavy metals on anionic drug efflux from renal proximal tubule.

    NARCIS (Netherlands)

    Terlouw, S.A.; Graeff, C.; Smeets, P.H.E.; Fricker, G.; Russel, F.G.M.; Masereeuw, R.; Miller, D.S.

    2002-01-01

    We recently demonstrated in isolated killifish renal proximal tubules that two classes of nephrotoxicants, aminoglycoside antibiotics and radiocontrast agents, rapidly decrease transport mediated by multidrug resistance protein 2 (Mrp2) by causing endothelin (ET) release and signaling through an

  13. Toxicity modulation, resistance enzyme evasion, and A-site X-ray structure of broad-spectrum antibacterial neomycin analogs.

    Science.gov (United States)

    Maianti, Juan Pablo; Kanazawa, Hiroki; Dozzo, Paola; Matias, Rowena D; Feeney, Lee Ann; Armstrong, Eliana S; Hildebrandt, Darin J; Kane, Timothy R; Gliedt, Micah J; Goldblum, Adam A; Linsell, Martin S; Aggen, James B; Kondo, Jiro; Hanessian, Stephen

    2014-09-19

    Aminoglycoside antibiotics are pseudosaccharides decorated with ammonium groups that are critical for their potent broad-spectrum antibacterial activity. Despite over three decades of speculation whether or not modulation of pKa is a viable strategy to curtail aminoglycoside kidney toxicity, there is a lack of methods to systematically probe amine-RNA interactions and resultant cytotoxicity trends. This study reports the first series of potent aminoglycoside antibiotics harboring fluorinated N1-hydroxyaminobutyryl acyl (HABA) appendages for which fluorine-RNA contacts are revealed through an X-ray cocrystal structure within the RNA A-site. Cytotoxicity in kidney-derived cells was significantly reduced for the derivative featuring our novel β,β-difluoro-HABA group, which masks one net charge by lowering the pKa without compromising antibacterial potency. This novel side-chain assists in evasion of aminoglycoside-modifying enzymes, and it can be easily transferred to impart these properties onto any number of novel analogs.

  14. Characterization of 3 Strains of Yersinia Pestis

    National Research Council Canada - National Science Library

    Kournikakis, B

    2000-01-01

    .... Antibiotic sensitivities showed that the 3 strains were sensitive to aminoglycosides, the cephalosporins/ cephams, most of the beta lactams/penicillins (e.g. ampicillin) and quinolones (e.g. ciprofloxacin...

  15. Bacillus Collagen Like Protein of Anthracis: Immunological and Functional Analyses

    Science.gov (United States)

    2007-09-21

    spectrum of anthrax disease. Cutaneous anthrax 14 The majority of naturally-acquired anthrax in humans is of the cutaneous form. Disease occurs...tetracycline, chloramphenicol, aminoglycosides, macrolides, imipenemlmeropenem, rifampicin, and vancomycin but resistant to cephalosporins , trimethoprim, and

  16. CK (Creatine Kinase) Test

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  17. Myasthenia Gravis Tests

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  18. HIV Genotypic Resistance Testing

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  19. With Home Testing, Consumers Take Charge of Their Health

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  20. Liver Panel

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  1. Mono Test

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  2. Pleural Fluid Analysis Test

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  3. Coagulation Factors Test

    Science.gov (United States)

    ... Blood Testing Alpha-1 Antitrypsin Alpha-fetoprotein (AFP) Tumor Marker AMAS Aminoglycoside Antibiotics Ammonia Amniocentesis Amylase ANCA/MPO/ ... Beta-2 Microglobulin Kidney Disease Beta-2 Microglobulin Tumor Marker Bicarbonate (Total CO2) Bilirubin Blood Culture Blood Gases ...

  4. In vitro susceptibility of Bartonella species to 17 antimicrobial compounds: comparison of Etest and agar dilution.

    NARCIS (Netherlands)

    Dorbecker, C.; Sander, A.; Oberle, K.; Schulin-Casonato, T.

    2006-01-01

    OBJECTIVES: In vitro susceptibility testing of 31 Bartonella spp. strains including 21 Bartonella henselae isolates was performed for 17 antimicrobial agents (telithromycin, four macrolides, five fluoroquinolones, five aminoglycosides, doxycycline and rifampicin). METHODS: MICs were determined by

  5. 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

    Partial sequence analysis of a tet(O) plasmid from a multiple-drug-resistant clinical isolate of Campylobacter jejuni revealed 10 genes or pseudogenes encoding different aminoglycoside inactivating enzymes, transposaselike genes...

  6. Methods for chemical synthesis of biologically active compounds using supramolecular protective groups and novel compounds obtainable Thereby

    NARCIS (Netherlands)

    Herrmann, Andreas; Bastian, Andreas Alexander; Marcozzi, Alessio

    2014-01-01

    The invention relates to drug development and synthetic chemistry, in particular to the manufacture of biologically active compounds based on naturally occurring molecules. It also relates to novel biologically active compounds, for example aminoglycoside antibiotics, in a substantially pure

  7. Cloning and DNA sequence analysis of an aac(3)-Vb gene from Serratia marcescens.

    OpenAIRE

    Rather, P N; Mierzwa, R; Hare, R S; Miller, G H; Shaw, K J

    1992-01-01

    The AAC(3)-V resistance mechanism is characterized by high-level resistance to the aminoglycosides gentamicin, netilmicin, 2'-N-ethylnetilmicin, and 6'-N-ethylnetilmicin and moderate resistance levels to tobramycin. Serratia marcescens 82041944 contains an AA(3)-V resistance mechanism as determined from aminoglycoside resistance profiles. This strain, however, does not exhibit hybridization with a probe derived from the previously cloned aac(3)-Va gene, (R. Allmansberger, B. Bräu, and W. Piep...

  8. Potential roles for DNA replication and repair functions in cell killing by streptomycin

    OpenAIRE

    Humayun, M. Zafri; Ayyappan, Vasudevan

    2013-01-01

    The aminoglycoside streptomycin binds to ribosomes to promote mistranslation and eventual inhibition of translation. Streptomycin kills bacteria, whereas many other non-aminoglycoside inhibitors of translation do not. Because mistranslation is now known to affect DNA replication, we asked if hydroxyurea, a specific inhibitor of DNA synthesis, affects killing, and find that hydroxyurea significantly attenuates killing by streptomycin. We find that the hydroxyl radical scavengers D-mannitol and...

  9. Klinik Örneklerden İzole edilen Enterokokların Vankomisin ve Yüksek Düzey Aminoglikozid Direncinin Araştırılması

    OpenAIRE

    ASLAN, Sebahat; ÖZTÜRK, Candan; DELİALİOĞLU, Nuran; EMEKDAŞ, Gürol

    2012-01-01

    Abstract Investigations on Vancomycin and High Level Aminoglycoside Resistance of Enterococci Isolates From Clinical Specimen Aim: In recent years, enterococci, is one of the leading causes of nosocomial infections. In this study, the identification of enterococci that were isolated from the clinical specimens of the patients admitted to our hospital was aimed in addition to the detection of the resistance to vancomycin along with high level resistance to aminoglycosides. Method: Fo...

  10. MexXY multidrug efflux system of Pseudomonas aeruginosa

    OpenAIRE

    Morita, Yuji; Tomida, Junko; Kawamura, Yoshiaki

    2012-01-01

    Anti-pseudomonas aminoglycosides, such as amikacin and tobramycin, are used in the treatment of Pseudomonas aeruginosa infections. However, their use is linked to the development of resistance. During the last decade, the MexXY multidrug efflux system has been comprehensively studied, and numerous reports of laboratory and clinical isolates have been published. This system has been increasingly recognized as one of the primary determinants of aminoglycoside resistance in P. aeruginosa. In P. ...

  11. AmgRS-mediated envelope stress-inducible expression of the mexXY multidrug efflux operon of Pseudomonas aeruginosa

    Science.gov (United States)

    Lau, Calvin Ho-Fung; Krahn, Thomas; Gilmour, Christie; Mullen, Erin; Poole, Keith

    2015-01-01

    AmgRS is an envelope stress-responsive two-component system and aminoglycoside resistance determinant in Pseudomonas aeruginosa that is proposed to protect cells from membrane damage caused by aminoglycoside-generated mistranslated polypeptides. Consistent with this, a ΔamgR strain showed increased aminoglycoside-promoted membrane damage, damage that was largely absent in AmgRS-activated amgS-mutant strains. Intriguingly, one such mutation, V121G, while providing for enhanced resistance to aminoglycosides, rendered P. aeruginosa susceptible to several ribosome-targeting nonaminoglycoside antimicrobials that are inducers and presumed substrates of the MexXY-OprM multidrug efflux system. Surprisingly, the amgSV121G mutation increased mexXY expression threefold, suggesting that export of these nonaminoglycosides was compromised in the amgSV121G mutant. Nonetheless, a link was established between AmgRS activation and mexXY expression and this was confirmed in studies showing that aminoglycoside-promoted mexXY expression is dependent on AmgRS. While nonaminoglycosides also induced mexXY expression, this was not AmgRS-dependent, consistent with these agents not generating mistranslated polypeptides and not activating AmgRS. The aminoglycoside inducibility of mexXY was abrogated in a mutant lacking the AmgRS target genes htpX and PA5528, encoding a presumed cytoplasmic membrane-associated protease and a membrane protein of unknown function, respectively. Thus, aminoglycoside induction of mexXY is a response to membrane damage and activation of the AmgRS two-component system. PMID:25450797

  12. AmgRS-mediated envelope stress-inducible expression of the mexXY multidrug efflux operon of Pseudomonas aeruginosa.

    Science.gov (United States)

    Lau, Calvin Ho-Fung; Krahn, Thomas; Gilmour, Christie; Mullen, Erin; Poole, Keith

    2015-02-01

    AmgRS is an envelope stress-responsive two-component system and aminoglycoside resistance determinant in Pseudomonas aeruginosa that is proposed to protect cells from membrane damage caused by aminoglycoside-generated mistranslated polypeptides. Consistent with this, a ΔamgR strain showed increased aminoglycoside-promoted membrane damage, damage that was largely absent in AmgRS-activated amgS-mutant strains. Intriguingly, one such mutation, V121G, while providing for enhanced resistance to aminoglycosides, rendered P. aeruginosa susceptible to several ribosome-targeting nonaminoglycoside antimicrobials that are inducers and presumed substrates of the MexXY-OprM multidrug efflux system. Surprisingly, the amgSV 121G mutation increased mexXY expression threefold, suggesting that export of these nonaminoglycosides was compromised in the amgSV 121G mutant. Nonetheless, a link was established between AmgRS activation and mexXY expression and this was confirmed in studies showing that aminoglycoside-promoted mexXY expression is dependent on AmgRS. While nonaminoglycosides also induced mexXY expression, this was not AmgRS-dependent, consistent with these agents not generating mistranslated polypeptides and not activating AmgRS. The aminoglycoside inducibility of mexXY was abrogated in a mutant lacking the AmgRS target genes htpX and PA5528, encoding a presumed cytoplasmic membrane-associated protease and a membrane protein of unknown function, respectively. Thus, aminoglycoside induction of mexXY is a response to membrane damage and activation of the AmgRS two-component system. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  13. Frequency and spectrum of mitochondrial 12S rRNA variants in 440 Han Chinese hearing impaired pediatric subjects from two otology clinics

    Directory of Open Access Journals (Sweden)

    Zhou Jianjin

    2011-01-01

    Full Text Available Abstract Background Aminoglycoside ototoxicity is one of the common health problems. Mitochondrial 12S rRNA mutations are one of the important causes of aminoglycoside ototoxicity. However, the incidences of 12S rRNA mutations associated with aminoglycoside ototoxicity are less known. Methods A total of 440 Chinese pediatric hearing-impaired subjects were recruited from two otology clinics in the Ningbo and Wenzhou cities of Zhejiang Province, China. These subjects underwent clinical, genetic evaluation and molecular analysis of mitochondrial 12S rRNA. Resultant mtDNA variants were evaluated by structural and phylogenetic analysis. Results The study samples consisted of 227 males and 213 females. The age of all participants ranged from 1 years old to 18 years, with the median age of 9 years. Ninety-eight subjects (58 males and 40 females had a history of exposure to aminoglycosides, accounting for 22.3% cases of hearing loss in this cohort. Molecular analysis of 12S rRNA gene identified 41 (39 known and 2 novel variants. The incidences of the known deafness-associated 1555A > G, 1494C > T and 1095T > C mutations were 7.5%, 0.45% and 0.91% in this entire hearing-impaired subjects, respectively, and 21.4%, 2% and 2% among 98 subjects with aminoglycoside ototoxicity, respectively. The structural and phylogenetic evaluations showed that a novel 747A > G variant and known 839A > G, 1027A > G, 1310C > T and 1413T > C variants conferred increased sensitivity to aminoglycosides or nonsyndromic deafness as they were absent in 449 Chinese controls and localized at highly conserved nucleotides of this rRNA. However, other variants were polymorphisms. Of 44 subjects carrying one of definite or putative deafness-related 12S rRNA variants, only one subject carrying the 1413T > C variant harbored the 235DelC/299DelAT mutations in the GJB2 gene, while none of mutations in GJB2 gene was detected in other 43 subjects. Conclusions Mutations in mitochondrial 12S r

  14. 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

  15. Occurrence and clonal diversity of multidrug-resistant Klebsiella pneumoniae recovered from inanimate surfaces in Algerian hospital environment: First report of armA, qnrB and aac(6')-Ib-cr genes.

    Science.gov (United States)

    Zenati, Karima; Sahli, Farida; Garcia, Vincent; Bakour, Sofiane; Belhadi, Djellali; Rolain, Jean Marc; Touati, Abdelaziz

    2017-09-01

    The aim of this study is to characterize the molecular support of antibiotic resistance in MDR Klebsiella pneumoniae recovered from inanimate surfaces between March 2012 to February 2014 in three teaching hospitals (Setif, Bejaia and Constantine) in Algeria. Forty-four K. pneumoniae producing ESBL were detected and bla CTX-M-15 and bla CTX-M-3 were detected respectively in 41 and 3 isolates. These K. pneumoniae isolates producing ESBL were also resistant to gentamicin (87%), tobramicin (87%), ciprofloxacin (66%) and ofloxacin (62%). Aminoglycosides resistance genes detected were 16S rRNA methylase (armA), aminoglycoside acetyl-transferase (aac(6')-Ib), aminoglycoside nucleotidyl-transferase (aadA2) and aminoglycoside, phosphoryl-transferase (ant3″Ih-aac(6')-IId). Plasmid-mediated quinolone resistance (PMQR) genes detected were aac(6')-Ib-cr (34 isolates) and qnrB genes in (34 isolates). Multilocus sequence typing (MLST) resulted in 12 different sequence types (STs) regrouped into 5 clonal complexes (CC147, CC17, CC37, CC2 and CC23), one clonal group (CG485) and 4 singletons (ST1426, ST405, ST1308, ST873). Here, we report the detection of the ESBLs encoding gene linked with plasmid-mediated quinolone resistance (PMQR) and aminoglycosides resistance recovered from inanimate surfaces in hospital environment. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  16. MexXY multidrug efflux system of Pseudomonas aeruginosa.

    Science.gov (United States)

    Morita, Yuji; Tomida, Junko; Kawamura, Yoshiaki

    2012-01-01

    Anti-pseudomonas aminoglycosides, such as amikacin and tobramycin, are used in the treatment of Pseudomonas aeruginosa infections. However, their use is linked to the development of resistance. During the last decade, the MexXY multidrug efflux system has been comprehensively studied, and numerous reports of laboratory and clinical isolates have been published. This system has been increasingly recognized as one of the primary determinants of aminoglycoside resistance in P. aeruginosa. In P. aeruginosa cystic fibrosis isolates, upregulation of the pump is considered the most common mechanism of aminoglycoside resistance. Non-fermentative Gram-negative pathogens possessing very close MexXY orthologs such as Achromobacter xylosoxidans and various Burkholderia species (e.g., Burkholderia pseudomallei and B. cepacia complexes), but not B. gladioli, are intrinsically resistant to aminoglycosides. Here, we summarize the properties (e.g., discovery, mechanism, gene expression, clinical significance) of the P. aeruginosa MexXY pump and other aminoglycoside efflux pumps such as AcrD of Escherichia coli, AmrAB-OprA of B. pseudomallei, and AdeABC of Acinetobacter baumannii. MexXY inducibility of the PA5471 gene product, which is dependent on ribosome inhibition or oxidative stress, is noteworthy. Moreover, the discovery of the cognate outer membrane component (OprA) of MexXY in the multidrug-resistant clinical isolate PA7, serotype O12 deserves special attention.

  17. MexXY multidrug efflux system of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Yuji eMorita

    2012-11-01

    Full Text Available Anti-pseudomonas aminoglycosides, such as amikacin and tobramycin, are used in the treatment of Pseudomonas aeruginosa infections. However, their use is linked to the development of resistance. During the last decade, the MexXY multidrug efflux system has been comprehensively studied, and numerous reports of laboratory and clinical isolates have been published. This system has been increasingly recognized as one of the primary determinants of aminoglycoside resistance in P. aeruginosa. In P. aeruginosa cystic fibrosis isolates, upregulation of the pump is considered the most common mechanism of aminoglycoside resistance. Non-fermentative Gram-negative pathogens possessing very close MexXY orthologues such as Achromobacter xylosoxidans and various Burkholderia species [e.g., B. pseudomallei and B. cepacia complexes], but not B. gladioli, are intrinsically resistant to aminoglycosides. Here, we summarize the properties (e.g., discovery, mechanism, gene expression, clinical significance of the P. aeruginosa MexXY pump and other aminoglycoside efflux pumps such as AcrD of Escherichia coli, AmrAB-OprA of B. pseudomallei, and AdeABC of Acinetobacter baumannii. MexXY inducibility of the PA5471 gene product, which is dependent on ribosome inhibition or oxidative stress, is noteworthy. Moreover, the discovery of the cognate outer membrane component (OprA of MexXY in the multidrug-resistant clinical isolate PA7, serotype O12 deserves special attention.

  18. Discovery of Antibiotics-derived Polymers for Gene Delivery using Combinatorial Synthesis and Cheminformatics Modeling

    Science.gov (United States)

    Potta, Thrimoorthy; Zhen, Zhuo; Grandhi, Taraka Sai Pavan; Christensen, Matthew D.; Ramos, James; Breneman, Curt M.; Rege, Kaushal

    2014-01-01

    We describe the combinatorial synthesis and cheminformatics modeling of aminoglycoside antibiotics-derived polymers for transgene delivery and expression. Fifty-six polymers were synthesized by polymerizing aminoglycosides with diglycidyl ether cross-linkers. Parallel screening resulted in identification of several lead polymers that resulted in high transgene expression levels in cells. The role of polymer physicochemical properties in determining efficacy of transgene expression was investigated using Quantitative Structure-Activity Relationship (QSAR) cheminformatics models based on Support Vector Regression (SVR) and ‘building block’ polymer structures. The QSAR model exhibited high predictive ability, and investigation of descriptors in the model, using molecular visualization and correlation plots, indicated that physicochemical attributes related to both, aminoglycosides and diglycidyl ethers facilitated transgene expression. This work synergistically combines combinatorial synthesis and parallel screening with cheminformatics-based QSAR models for discovery and physicochemical elucidation of effective antibiotics-derived polymers for transgene delivery in medicine and biotechnology. PMID:24331709

  19. Discovery of antibiotics-derived polymers for gene delivery using combinatorial synthesis and cheminformatics modeling.

    Science.gov (United States)

    Potta, Thrimoorthy; Zhen, Zhuo; Grandhi, Taraka Sai Pavan; Christensen, Matthew D; Ramos, James; Breneman, Curt M; Rege, Kaushal

    2014-02-01

    We describe the combinatorial synthesis and cheminformatics modeling of aminoglycoside antibiotics-derived polymers for transgene delivery and expression. Fifty-six polymers were synthesized by polymerizing aminoglycosides with diglycidyl ether cross-linkers. Parallel screening resulted in identification of several lead polymers that resulted in high transgene expression levels in cells. The role of polymer physicochemical properties in determining efficacy of transgene expression was investigated using Quantitative Structure-Activity Relationship (QSAR) cheminformatics models based on Support Vector Regression (SVR) and 'building block' polymer structures. The QSAR model exhibited high predictive ability, and investigation of descriptors in the model, using molecular visualization and correlation plots, indicated that physicochemical attributes related to both, aminoglycosides and diglycidyl ethers facilitated transgene expression. This work synergistically combines combinatorial synthesis and parallel screening with cheminformatics-based QSAR models for discovery and physicochemical elucidation of effective antibiotics-derived polymers for transgene delivery in medicine and biotechnology. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Identification of RNA-ligand interactions by affinity electrophoresis.

    Science.gov (United States)

    Boodram, Sherry N; Cho, Chul M; Tavares, Tony J; Johnson, Philip E

    2011-02-01

    We have developed an affinity electrophoresis method to screen for RNA-ligand interactions. Native polyacrylamide gels were polymerized in the absence and presence of different RNA binding molecules. Binding is indicated by a difference in mobility between the gel with ligand present and the gel with no ligand present. The utility of this method was demonstrated using the known interaction between the Escherichia coli ribosomal A-site RNA and different aminoglycoside ligands. The RNA-aminoglycoside interaction observed is dose dependent, and the affinity mirrors what is observed in solution. In addition, we used this method to gauge the affinity to different aminoglycoside molecules of an RNA molecule derived from the thymidylate synthase mRNA construct that contains a CC mismatch. Copyright © 2010 Elsevier Inc. All rights reserved.

  1. Carbon Sources Tune Antibiotic Susceptibility in Pseudomonas aeruginosa via Tricarboxylic Acid Cycle Control.

    Science.gov (United States)

    Meylan, Sylvain; Porter, Caroline B M; Yang, Jason H; Belenky, Peter; Gutierrez, Arnaud; Lobritz, Michael A; Park, Jihye; Kim, Sun H; Moskowitz, Samuel M; Collins, James J

    2017-02-16

    Metabolically dormant bacteria present a critical challenge to effective antimicrobial therapy because these bacteria are genetically susceptible to antibiotic treatment but phenotypically tolerant. Such tolerance has been attributed to impaired drug uptake, which can be reversed by metabolic stimulation. Here, we evaluate the effects of central carbon metabolite stimulations on aminoglycoside sensitivity in the pathogen Pseudomonas aeruginosa. We identify fumarate as a tobramycin potentiator that activates cellular respiration and generates a proton motive force by stimulating the tricarboxylic acid (TCA) cycle. In contrast, we find that glyoxylate induces phenotypic tolerance by inhibiting cellular respiration with acetyl-coenzyme A diversion through the glyoxylate shunt, despite drug import. Collectively, this work demonstrates that TCA cycle activity is important for both aminoglycoside uptake and downstream lethality and identifies a potential strategy for potentiating aminoglycoside treatment of P. aeruginosa infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. [Antibiotic sensitivity of strains of Klebsiella isolated in Geneva and Algiers].

    Science.gov (United States)

    Sekfali, K; Rahal, K; Ducel, G

    1989-01-01

    573 strains of Klebsiella were isolated in Geneva (239 strains) and in Algiers (334 strains). The complete work with bacteriologic features (culture, biochemistry and antigenicity) will be published later. Two investigations took place in surgical cardio-vascular service in Geneva cantonal hospital and in Algiers hospitals: Pediatric (Beni-Messous) and intensive care service (Mustapha). High resistance percentages are found with Penicillins (greater than 60% by C.M.I.) in Geneva and Algiers. The strains are susceptible to aminoglycosides: in Algiers, 8.68% strains are resistant to Gentamicin and 5.99% to Tobramycin. In Geneva, all the strains are susceptible to Aminoglycosides. All the strains are susceptible to Trimethoprim and the Furans resistant strains are rare. The C.M.I. test is more precise than disc diffusion technique, especially for Penicillin and Furans. Cephalosporins and aminoglycosides are the best choice for treatment of Klebsiella infections.

  3. Histone Deacetylase Inhibitors Are Protective in Acute but Not in Chronic Models of Ototoxicity

    Directory of Open Access Journals (Sweden)

    Chao-Hui Yang

    2017-10-01

    Full Text Available Previous studies have reported that modification of histones alters aminoglycoside-induced hair cell death and hearing loss. In this study, we investigated three FDA-approved histone deacetylase (HDAC inhibitors (vorinostat/SAHA, belinostat, and panobinostat as protectants against aminoglycoside-induced ototoxicity in murine cochlear explants and in vivo in both guinea pigs and CBA/J mice. Individually, all three HDAC inhibitors reduced gentamicin (GM-induced hair cell loss in a dose-dependent fashion in explants. In vivo, however, treatment with SAHA attenuated neither GM-induced hearing loss and hair cell loss in guinea pigs nor kanamycin (KM-induced hearing loss and hair cell loss in mice under chronic models of ototoxicity. These findings suggest that treatment with the HDAC inhibitor SAHA attenuates aminoglycoside-induced ototoxicity in an acute model, but not in chronic models, cautioning that one cannot rely solely on in vitro experiments to test the efficacy of otoprotectant compounds.

  4. Structure and function of the human megalin receptor

    DEFF Research Database (Denmark)

    Dagil, Robert

    of aminoglycosides during antibacterial treatment, which can lead to nephro- and ototoxic side-effects. This thesis presents new insights into the structure-function relation of the megalin receptor. The interaction between megalin and several natural protein ligands as well as the aminoglycoside gentamicin...... were involved in binding, which utilizes the commonly found ligand binding motif. The details of the atomic resolutionmodel will aid the future design of effective megalin antagonists, however, since the common ligand binding motif of CR domains is used to bind gentamicin this may not be a trivial task...

  5. Structure and function of the human megalin receptor

    DEFF Research Database (Denmark)

    Dagil, Robert

    Megalin is an endocytic lipoprotein receptor expressed widely throughout the body, ranging from the proximal tubule in the kidneys to the cochlea in the inner ear. Megalin is known to bind over 50 different ligands and is involved in protein clearance of the renal ultrafiltrate via endocytosis...... of aminoglycosides during antibacterial treatment, which can lead to nephro- and ototoxic side-effects. This thesis presents new insights into the structure-function relation of the megalin receptor. The interaction between megalin and several natural protein ligands as well as the aminoglycoside gentamicin...

  6. Susceptibility-resistance profile of micro-organisms isolated from ...

    African Journals Online (AJOL)

    were sensitive to the fluoroquinolones (ciprofloxacin, 85.3%, norfloxacin 93.3%) and the aminoglycosides (streptomycin 90%, gentamycin 89.3%). However, the isolates demonstrated significant resistance to common antibiotics like penicillins (augmentin [amoxycillin-cavulanic acid combination] 80%, cloxacillin 88.3%, ...

  7. Widespread transfer of resistance genes between bacterial species in an intensive care unit: Implications for hospital epidemiology

    NARCIS (Netherlands)

    Al Naiemi, Nashwan; Duim, Birgitta; Savelkoul, Paul H. M.; Spanjaard, Lodewijk; de Jonge, Evert; Bart, Aldert; Vandenbroucke-Grauls, Christina M.; de Jong, Menno D.

    2005-01-01

    A transferable plasmid encoding SHV-12 extended-spectrum beta-lactamase, TEM-116, and aminoglycoside resistance was responsible for two sequential clonal outbreaks of Enterobacter cloacae and Acinetobacter baumannii bacteria. A similar plasmid was present among isolates of four different bacterial

  8. Immunoassay Analysis of Kanamycin in Serum Using the Tobramycin Kit

    NARCIS (Netherlands)

    Dijkstra, J. A.; Voerman, A. J.; Greijdanus, B.; Touw, D. J.; Alffenaar, J. W. C.

    Kanamycin is one of the aminoglycosides used in the treatment of multidrug-resistant tuberculosis. Blood concentrations of kanamycin are predictive for the treatment efficacy and the occurrence of side effects, and dose adjustments can be needed to optimize therapy. However, an immunoassay method

  9. NEONATAL SEPTICAEMIA IN LOW BIRTH WEIGHT INFANTS AT ...

    African Journals Online (AJOL)

    2005-03-03

    Mar 3, 2005 ... Conclusion: Case fatality rate for low birth weight infants with sepsis is high. Gram negative organisms are the predominant pathogens. No maternal risk factors were identified. Antibiotic sensitivity shows adequate sensitivity to aminoglycosides and third generation cephalosporins. INTRODUCTION.

  10. Evaluation of antibacterial, antifungal and modulatory activity of ...

    African Journals Online (AJOL)

    Methods: The tests for the minimum inhibitory concentration and modulation of microbial resistance, with the use of ethanolic and methanolic extracts of Padina Sanctae-cruces combined with drugs of the class of aminoglycosides and antifungal were used to evaluate the activity against the cited microorganisms. Results: ...

  11. Case report

    African Journals Online (AJOL)

    formulations should be used if available. Frequently measure aminoglycoside trough concentrations and renal function and adjust the dose as required or prescribe alternative drugs. A continuous decrease in glomerular filtration rate shortly after ACE-I initiation should raise the suspicion of bilateral renal artery stenosis and ...

  12. Time course of cochlear electrophysiology and morphology after combined administration of kanamycin and furosemide.

    NARCIS (Netherlands)

    Versnel, H.; Agterberg, M.J.H.; de Groot, J.C.M.J.; Smoorenburg, G.F.; Klis, S.F.L.

    2007-01-01

    In animal models of deafness, administration of an aminoglycoside in combination with a loop diuretic is often applied to produce a rapid loss of cochlear hair cells. However, the extent to which surviving hair cells remain functional after such a deafening procedure varies. In a longitudinal

  13. The fate of inhaled antibiotics after deposition in cystic fibrosis: How to get drug to the bug?

    Science.gov (United States)

    Bos, Aukje C; Passé, Kimberly M; Mouton, Johan W; Janssens, Hettie M; Tiddens, Harm A W M

    2017-01-01

    Chronic airway infections in patients with cystic fibrosis (CF) are most often treated with inhaled antibiotics of which deposition patterns have been extensively studied. However, the journey of aerosol particles does not end after deposition within the bronchial tree. To review how local conditions affect the clinical efficacy of antibiotic aerosol particles after deposition in the airways of patients with CF. Electronic databases were searched from inception to September 2015. Original studies describing the effect of CF sputum or bacterial factors on antibiotic efficacy and formulations to increase efficacy were included. 35 articles were included which mostly described in vitro studies and mainly investigated aminoglycosides. After deposition, diffusion through the mucus layer was reduced for aminoglycosides, β-lactam antibiotics and fluoroquinolones. Within CF mucus, low oxygen tension adversely affected aminoglycosides, β-lactam antibiotics, and chloramphenicol; and molecules inactivated aminoglycosides but not β-lactam antibiotics. Finally, the alginate layer surrounding Pseudomonas aeruginosa was an important factor in the resistance against all antibiotics. After deposition in the airways, the local efficacy of inhaled antibiotics can be reduced by molecules within CF mucus and the alginate layer surrounding P. aeruginosa. Copyright © 2017 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  14. Antibiotic Resistance of Bacteria: A Global Challenge

    Indian Academy of Sciences (India)

    vealed several aminoglycoside resistances in nonculturable bac- teria. Notwithstanding the availability of so many antimicrobial agents, infectious diseases still remain the second leading cause of death worldwide. Eventually, the widespread occurrence of antibiotic-resistant bacteria has added a new dimension to the.

  15. Lack of antimicrobial bactericidal activity in Mycobacterium abscessus.

    Science.gov (United States)

    Maurer, Florian P; Bruderer, Vera L; Ritter, Claudia; Castelberg, Claudio; Bloemberg, Guido V; Böttger, Erik C

    2014-07-01

    Antibiotic therapy of infections caused by the emerging pathogen Mycobacterium abscessus is challenging due to the organism's natural resistance toward most clinically available antimicrobials. We investigated the bactericidal activity of antibiotics commonly administered in M. abscessus infections in order to better understand the poor therapeutic outcome. Time-kill curves were generated for clinical M. abscessus isolates, Mycobacterium smegmatis, and Escherichia coli by using antibiotics commonly categorized as bactericidal (amikacin and moxifloxacin) or bacteriostatic (tigecycline and linezolid). In addition, the impact of aminoglycoside-modifying enzymes on the mode of action of substrate and nonsubstrate aminoglycosides was studied by using M. smegmatis as a model organism. While amikacin and moxifloxacin were bactericidal against E. coli, none of the tested compounds showed bactericidal activity against M. abscessus. Further mechanistic investigations of the mode of action of aminoglycosides in M. smegmatis revealed that the bactericidal activity of tobramycin and gentamicin was restored by disruption of the chromosomal aac(2') gene in the mycobacterial genome. The lack of bactericidal antibiotics in currently recommended treatment regimens provides a reasonable explanation for the poor therapeutic outcome in M. abscessus infection. Our findings suggest that chromosomally encoded drug-modifying enzymes play an important role in the lack of aminoglycoside bactericidal activity against rapidly growing mycobacteria. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  16. Surveillance of multidrug resistant bacteria pathogens from female ...

    African Journals Online (AJOL)

    oyaide

    2013-06-26

    Jun 26, 2013 ... pregnancy loss, and in association with pregnancy, morbidity to both the mother and child increases. In the present work .... In the case of E. coli, aminoglycosides groups of anti- biotics showed 100% inhibition followed by the fluroquin- dones class of antibiotics (Table 3). The penicillin group of antibiotics ...

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

    NARCIS (Netherlands)

    Batchelor, M.; Hopkins, K.L.; Liebana, E.; Slickers, P.; Ehricht, R.; Mafura, M.; Aerestrup, F.; Mevius, D.J.; Clifton-Hadley, F.A.; Woodward, M.; Davies, R.; Threlfall, J.; Anjum, F.M.

    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 ß-lactams, including extended-spectrum

  18. Enterococcus faecalis infective endocarditis

    DEFF Research Database (Denmark)

    Dahl, Anders; Rasmussen, Rasmus V; Bundgaard, Henning

    2013-01-01

    Because of the nephrotoxic effects of aminoglycosides, the Danish guidelines on infective endocarditis were changed in January 2007, reducing gentamicin treatment in enterococcal infective endocarditis from 4 to 6 weeks to only 2 weeks. In this pilot study, we compare outcomes in patients...... with Enterococcus faecalis infective endocarditis treated in the years before and after endorsement of these new recommendations....

  19. Author Details

    African Journals Online (AJOL)

    The effect of oral levodopa on the visual acuities of Nigerian amblyopes. Abstract · Vol 10, No 1-2 (2008) - Articles Phytochemical and proximate assays of cyperus esculentus Linn, (Tigger nut) Abstract · Vol 10, No 3 (2008) - Articles In vitro effect of aminoglycosides and fluoroquinolones on staphylococcus aureus in the ...

  20. Melatonin mitigates neomycin-induced hair cell injury in zebrafish.

    Science.gov (United States)

    Oh, Kyoung Ho; Rah, Yoon Chan; Hwang, Kyu Ho; Lee, Seung Hoon; Kwon, Soon Young; Cha, Jae Hyung; Choi, June

    2017-10-01

    Ototoxicity due to medications, such as aminoglycosides, is irreversible, and free radicals in the inner ear are assumed to play a major role. Because melatonin has an antioxidant property, we hypothesize that it might mitigate hair cell injury by aminoglycosides. The objective of this study was to evaluate whether melatonin has an alleviative effect on neomycin-induced hair cell injury in zebrafish (Danio rerio). Various concentrations of melatonin were administered to 5-day post-fertilization zebrafish treated with 125 μM neomycin for 1 h. Surviving hair cells within four neuromasts were compared with that of a control group. Apoptosis was assessed via terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The changes of ultrastructure were confirmed using a scanning electron microscope. Melatonin alleviated neomycin-induced hair cell injury in neuromasts (neomycin + melatonin 100 μM: 13.88 ± 0.91 cells, neomycin only: 7.85 ± 0.90 cells; n = 10, p melatonin for 1 h in SEM findings. Melatonin is effective in alleviating aminoglycoside-induced hair cell injury in zebrafish. The results of this study demonstrated that melatonin has the potential to reduce apoptosis induced by aminoglycosides in zebrafish.

  1. Clinical Guidelines

    African Journals Online (AJOL)

    diclofenac). Start empirical IP treatment with a first and third. • generation cephalosporin (e.g. cefazolin plus ceftazidime). Aminoglycosides can be used as alternatives to third generation cephalosporins for gram .... threatening manner about the possible mechanism of the episode (e.g. poor aseptic technique, lack of clean.

  2. Polyclonal KPC-3-producing Enterobacteriaceae in Portugal

    OpenAIRE

    Manageiro, Vera; Ferreira, Eugénia; Louro, Deolinda; Caniça, Manuela; Antimicrobial Resistance Surveillance Program in Portugal (ARSIP)

    2012-01-01

    Water has been recognized as a reservoir for antibiotic resistance genes (ARG), where the presence of mobile genetic elements, including plasmids, favors their dissemination. It is noteworthy that nonpathogenic environmental organisms, where plasmids encoding multiple ARG are prevalent, can provide resistance to most classes of antimicrobials including beta-lactams, aminoglycosides, chloramphenicol, trimethoprim, streptomycin, fosfomycin, quinolones, among others. The main goal of...

  3. Diversity of β-lactamase-encoding genes among Gram-negative isolates from water samples in Northern Portugal

    OpenAIRE

    Manageiro, Vera; Ferreira, Eugénia; Figueira, Vânia; Manaia, Célia M.; Caniça, Manuela

    2012-01-01

    Water has been recognized as a reservoir for antibiotic resistance genes (ARG), where the presence of mobile genetic elements, including plasmids, favors their dissemination. It is noteworthy that non- pathogenic environmental organisms, where plasmids encoding multiple ARG are prevalent, can provide resistance to most classes of antimicrobials including :-lactams, aminoglycosides, chloramphenicol, trimethoprim, streptomycin, fosfomycin, q...

  4. Download this PDF file

    African Journals Online (AJOL)

    Prof. Khoza-Shangase

    2016-09-19

    Sep 19, 2016 ... It is important to note that vestibular symptoms may present with hearing symptoms because the medications may be vestibulocochleatoxic, and so South. African patients on HAART and aminoglycosides simultaneously are more likely to acquire a sensorineural hearing loss, tinnitus and vestibular damage ...

  5. Drugs and the kidney

    African Journals Online (AJOL)

    Hypokalaemia. • Volume depletion (prerenal uraemia). • Tinnitus (acts within the cochlea – can synergise with aminoglycoside antibiotics. Oral bioavailability between. 10% and 90%. Acts at luminal side of the thick ascending limb (NaK2Cl transporter). Highly protein bound. Rebound after single dose. T½: 4 hours. Thiazide.

  6. A prospective amikacin in a study of long-term use of paediatrics ...

    African Journals Online (AJOL)

    Amikacin (Amikin; B-M) was used as the only aminoglycoside for 18 months in a paediatric department within a general hospital because of high levels of resistance of Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterobacter cloacae isolates to tobramycin, gentamicin and netilmicin. Between 1 February 1987 ...

  7. Download

    African Journals Online (AJOL)

    Amikacin (Amikin; B-M) was used as the only aminoglycoside for 18 months in a paediatric department within a general hospital because of high levels of resistance of Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterobacter cloacae isolates to tobramycin, gentamicin and netilmicin. Between 1 February 1987 ...

  8. Chronic otorrhoea: Spectrum of microorganisms and antibiotic ...

    African Journals Online (AJOL)

    Otorrhoea had a different microbial spectrum compared with international reports, with methicillin-resistant Staphylococcus aureus infection in a single patient. The organisms isolated were susceptible mainly to fluoroquinolones (96%) and aminoglycosides (81%). Conclusion. Amoxicillin is a poor choice of antibiotic due to ...

  9. ORIGINAL ARTICLES

    African Journals Online (AJOL)

    Asthma. Prophylaxis for influenza virus. Aminoglycoside inhalations. Ibuprofen daily. Inhaled bronchodilators for relief of acute attacks. Inhaled anti-inflammatory agents for prophylaxis of moderate or severe asthma. Annual influenza vaccine. Two antibiotics should be used for PA. May reduce clinical symptoms and improve.

  10. Conformational Response of 30S-bound IF3 to A-Site Binders Streptomycin and Kanamycin.

    Science.gov (United States)

    Chulluncuy, Roberto; Espiche, Carlos; Nakamoto, Jose Alberto; Fabbretti, Attilio; Milón, Pohl

    2016-12-13

    Aminoglycoside antibiotics are widely used to treat infectious diseases. Among them, streptomycin and kanamycin (and derivatives) are of importance to battle multidrug-resistant (MDR) Mycobacterium tuberculosis . Both drugs bind the small ribosomal subunit (30S) and inhibit protein synthesis. Genetic, structural, and biochemical studies indicate that local and long-range conformational rearrangements of the 30S subunit account for this inhibition. Here, we use intramolecular FRET between the C- and N-terminus domains of the flexible IF3 to monitor real-time perturbations of their binding sites on the 30S platform. Steady and pre-steady state binding experiments show that both aminoglycosides bring IF3 domains apart, promoting an elongated state of the factor. Binding of Initiation Factor IF1 triggers closure of IF3 bound to the 30S complex, while both aminoglycosides revert the IF1-dependent conformation. Our results uncover dynamic perturbations across the 30S subunit, from the A-site to the platform, and suggest that both aminoglycosides could interfere with prokaryotic translation initiation by modulating the interaction between IF3 domains with the 30S platform.

  11. Conformational Response of 30S-bound IF3 to A-Site Binders Streptomycin and Kanamycin

    Directory of Open Access Journals (Sweden)

    Roberto Chulluncuy

    2016-12-01

    Full Text Available Aminoglycoside antibiotics are widely used to treat infectious diseases. Among them, streptomycin and kanamycin (and derivatives are of importance to battle multidrug-resistant (MDR Mycobacterium tuberculosis. Both drugs bind the small ribosomal subunit (30S and inhibit protein synthesis. Genetic, structural, and biochemical studies indicate that local and long-range conformational rearrangements of the 30S subunit account for this inhibition. Here, we use intramolecular FRET between the C- and N-terminus domains of the flexible IF3 to monitor real-time perturbations of their binding sites on the 30S platform. Steady and pre-steady state binding experiments show that both aminoglycosides bring IF3 domains apart, promoting an elongated state of the factor. Binding of Initiation Factor IF1 triggers closure of IF3 bound to the 30S complex, while both aminoglycosides revert the IF1-dependent conformation. Our results uncover dynamic perturbations across the 30S subunit, from the A-site to the platform, and suggest that both aminoglycosides could interfere with prokaryotic translation initiation by modulating the interaction between IF3 domains with the 30S platform.

  12. Predictive Value of Prior Colonization and Antibiotic Use for Third-Generation Cephalosporin-Resistant Enterobacteriaceae Bacteremia in Patients With Sepsis

    NARCIS (Netherlands)

    Rottier, Wouter C.; Bamberg, Yara R. P.; Dorigo-Zetsma, J. Wendelien; van der Linden, Paul D.; Ammerlaan, Heidi S. M.; Bonten, Marc J. M.

    2015-01-01

    Background. To prevent inappropriate empiric antibiotic treatment in patients with bacteremia caused by third-generation cephalosporin (3GC)-resistant Enterobacteriaceae (3GC-R EB), Dutch guidelines recommend beta-lactam and aminoglycoside combination therapy or carbapenem monotherapy in patients

  13. Characterization of class 1 integrons associated with R-plasmids in clinical Aeromonas salmonicida isolates from various geographical areas

    DEFF Research Database (Denmark)

    Schmidt, A.S.; Bruun, Morten Sichlau; Larsen, J.L.

    2001-01-01

    Class 1 integrons were found in 26 of 40 antibiotic-resistant isolates of the fish pathogen Aeromonas salmonicida from Northern Europe and North America. Three different dhfr genes, conferring trimethoprim resistance, and one ant(3 " )1a aminoglycoside resistance gene were identified as gene...

  14. Infectious drug resistance during an outbreak of salmonellosis

    International Nuclear Information System (INIS)

    Botha, P.; Hirsch, S.; Harley, E.; Elisha, G.; Pratt, K.; Bain, A.; Destroo, L.

    1980-01-01

    The sudden acquisition of aminoglycoside resistance among Salmonella group C 1 isolates causing summer diarrhoea raised the possibility of plasmid-mediated resistance. The demonstration of circular DNA species in the resistant, but not in the sensitive salmonellae and the transfer by conjugation of antibiotic resistance to a sensitive strain of Escherichia coli, was consistent with plasmid-mediated resistance

  15. Neonatal septicaemia in low birth weight infants at Kenyatta ...

    African Journals Online (AJOL)

    The common organisms isolated were gram negative organisms 60 (66.6%), while gram positive organisms were 30 (33.4%). Antibiotic sensitivity revealed high resistance to ampicillin and good sensitivity to aminoglycosides, third generation cephalosporins, clavulanic acid potentiated amoxycillin and chloramphenicol.

  16. Risk factors for hearing loss in neonates

    Directory of Open Access Journals (Sweden)

    Ni Luh Putu Maharani

    2016-11-01

    Full Text Available Background An estimated 6 of 1,000 children with live births suffer from permanent hearing loss at birth or the neonatal period. At least 90% of cases occur in developing countries. Hearing loss should be diagnosed as early as possible so that intervention can be done before the age of 6 months. Objective To determine risk factors for hearing loss in neonates. Methods We performed a case-control study involving 100 neonates with and without hearing loss who were born at Sanglah Hospital, Denpasar from November 2012 to February 2013. Subjects were consisted of 2 groups, those with hearing loss (case group of 50 subjects and without hearing loss (control group of 50 subjects. The groups were matched for gender and birth weight. We assessed the following risk factors for hearing loss: severe neonatal asphyxia, hyperbilirubinemia, meningitis, history of aminoglycoside therapy, and mechanical ventilation by Chi-square analysis. The results were presented as odds ratio and its corresponding 95% confidence intervals. Results Seventy percent of neonates with hearing loss had history of aminoglycoside therapy. Multivariable analysis revealed that aminoglycoside therapy of 14 days or more was a significant risk factor for hearing loss (OR 2.7; 95%CI 1.1 to 6.8; P=0.040. There were no statistically significant associations between hearing loss and severe asphyxia, hyperbilirubinemia, meningitis, or mechanical ventilation. Conclusion Aminoglycoside therapy for >=14 days was identified as a risk factor for hearing loss in neonates.

  17. Systemic ototoxicity: a review | Shine | East African Medical Journal

    African Journals Online (AJOL)

    Objectives: To review the literature pertaining to the ototoxic potential of three frequently prescribed systemic medications in the sub-Saharan setting; quinine, furosemide and aminoglycoside antibiotics. The pathophysiology, clinical manifestations and risk factors and risk minimisation strategies regarding the ototoxicity ...

  18. Susceptibility-resistance profile of micro-organisms isolated from ...

    African Journals Online (AJOL)

    SERVER

    2007-12-17

    Dec 17, 2007 ... were sensitive to the fluoroquinolones (ciprofloxacin, 85.3%, norfloxacin 93.3%) and the aminoglycosides (streptomycin 90% ... of pathogenic spoilage organisms from product to consumers (Grigo, 1976; Mendie et al., 1993). ...... The booming US Botanical Market. A new overview. Herbalgram 44: 33-36.

  19. Carbon Sources Tune Antibiotic Susceptibility in Pseudomonas aeruginosa via Tricarboxylic Acid Cycle Control

    OpenAIRE

    Meylan, Sylvain; Porter, Caroline B.M.; Yang, Jason H.; Belenky, Peter; Gutierrez, Arnaud; Lobritz, Michael A.; Park, Jihye; Kim, Sun H.; Moskowitz, Samuel M.; Collins, James J.

    2017-01-01

    Metabolically dormant bacteria present a critical challenge to effective antimicrobial therapy because these bacteria are genetically susceptible to antibiotic treatment but phenotypically tolerant. Such tolerance has been attributed to impaired drug uptake, which can be reversed by metabolic stimulation. Here, we evaluate the effects of central carbon metabolite stimulations on aminoglycoside sensitivity in the pathogen Pseudomonas aeruginosa. We identify fumarate as a tobramycin potentiator...

  20. Instrumental characterization of the smectite clay–gentamicin hybrids

    Indian Academy of Sciences (India)

    This paper focusses on the intercalation of clay mineral with gentamicin (an aminoglycoside antibiotic). The smectite clay–gentamicin hybrids were prepared by a solution intercalation at 60°C and the process was carried out on unmodified smectite clay and on smectite after Na+ ionic activation. The resulting ...

  1. 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

  2. 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.

  3. 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.

  4. original article

    African Journals Online (AJOL)

    available for the clinicians include the aminoglycosides, ureidopenicillin, ceftazidime, carbapenem and ciprofloxacin (19, 23). In the local setting, ceſtazidime is considered as one reserve drug for multi drug resistant organism including. Pseudomonas species. From our study, ceftazidime resistant strains tend to be sensitive ...

  5. ARTICLES -

    African Journals Online (AJOL)

    transfer of resistant bacterial pathogens is increased. The emergence of resistant bacteria is, however, a global problem affecting not only nosocomial but also community-acquired infections. .... Quinolone or carbapenem plus aminoglycoside. • Carbapenem monotherapy. Potential additions to each regimen could be.

  6. Prevalence of 16S rRNA methylase genes among b-lactamase ...

    African Journals Online (AJOL)

    2014-07-07

    Jul 7, 2014 ... resistant Gram negative bacterial strains, which pose challenges in an era when new antibiotic choices are limited (1, 2). Multidrug resistant strains are intermediate or resistant to at least three drugs in the classes of b- lactams, carbapenems, aminoglycosides, and fluoroquino- lones, whereas pan-drug ...

  7. 1591-IJBCS-Article-Chukaeney Abbey Modubuattah+

    African Journals Online (AJOL)

    hp

    to carbapenems). They are resistant to sulfamethoxazole-trimethoprim but remain susceptible to fluoro-quinolones and aminoglycosides. This resistance pattern is an emerging problem for Diarrheagenic E. coli. (DEC) strains isolated from children in other developing countries and for other enterobacteria worldwide.

  8. 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.

  9. 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.

  10. Quorum Sensing-Regulated Phenol-Soluble Modulins Limit Persister Cell Populations in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Bojer, Martin S; Lindemose, Søren; Vestergaard, Martin

    2018-01-01

    properties; however, the persister reducing activity was specifically linked to synthesis of the PSMα family. Correspondingly, a high-persister phenotype of a PSMα mutant was observed upon fluoroquinolone or aminoglycoside challenge, demonstrating that the persister reducing activity of PSMs can...

  11. A water-soluble pillar[5]arene as a new carrier for an old drug.

    Science.gov (United States)

    Barbera, Lucia; Franco, Domenico; De Plano, Laura M; Gattuso, Giuseppe; Guglielmino, Salvatore P P; Lentini, Germana; Manganaro, Nadia; Marino, Nino; Pappalardo, Sebastiano; Parisi, Melchiorre F; Puntoriero, Fausto; Pisagatti, Ilenia; Notti, Anna

    2017-04-11

    The remarkable affinity of deca-carboxylatopillar[5]arene WP5 towards the aminoglycoside antibiotic, amikacin, in aqueous media is reported; in vitro studies on Gram-positive bacteria (Staphylococcus aureus) show that drug entrapment inside WP5 also takes place in the presence of the microrganisms, thus pointing to WP5 as an appealing carrier for amikacin targeted delivery.

  12. Sugammadex Improves Neuromuscular Function in Patients ...

    African Journals Online (AJOL)

    2018-02-23

    Feb 23, 2018 ... aminoglycosides), history of allergy to neuromuscular blocking agents, opioids or other drugs, and alcohol and drug dependence. Patients were divided into two ... titration microcalorimetry investigated the likelihood of the formation of complexes between sugammadex and other steroidal and nonsteroidal ...

  13. THE DISCHARGING EAR: A PRACTICAL APPROACH

    African Journals Online (AJOL)

    Enrique

    brospinal fluid (CSF) and saliva. Wax is the normal secretion of the glands of the external ear canal, and patients .... acidic pH. They are effective against. P. aeruginosa, S. aureus, Proteus spp. and Candida. The aminoglycosides, polymyxin B, chloramphenicol and acetic acid are potentially ototoxic, the greatest risk of.

  14. In vitro activity of ceftriaxone alone and in combination with gentamicin, tobramycin, and amikacin against Pseudomonas aeruginosa.

    OpenAIRE

    Watanakunakorn, C

    1983-01-01

    The in vitro activity of ceftriaxone alone and in combination with gentamicin, tobramycin, and amikacin against 50 Pseudomonas aeruginosa strains was studied by the broth dilution method and the time-kill curve method. The majority of the P. aeruginosa strains tested were resistant to ceftriaxone. Combining ceftriaxone with the aminoglycosides resulted in synergism, antagonism, or indifference.

  15. Southern African Journal of HIV Medicine - Vol 12, No 1 (2011)

    African Journals Online (AJOL)

    The risks of concurrent treatment with tenofovir and aminoglycosides in patients with HIV-associated tuberculosis · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. C Kenyon, N Wearne, R Burton, G Meintjes, 43-45. http://dx.doi.org/10.4102/sajhivmed.v12i1.214 ...

  16. Adaptive resistance to cationic compounds in Pseudomonas aeruginosa.

    Science.gov (United States)

    Skiada, Anna; Markogiannakis, Antonis; Plachouras, Diamantis; Daikos, George L

    2011-03-01

    Adaptive resistance is an autoregulated phenomenon characterised by induction of resistance in the presence of drug and reversal to the sensitive phenotype in its absence. This type of resistance is well documented for polycationic antibiotics, including aminoglycosides and polymyxins, in Pseudomonas aeruginosa and other aerobic Gram-negative bacilli. It is not caused by selection of resistant mutants but rather by phenotypic alterations in order to survive the lethal drug effect. Adaptive resistance to aminoglycosides is mainly mediated by the MexXY-OprM efflux pump that is rapidly upregulated in bacteria surviving the first exposure to aminoglycosides and is downregulated when bacteria are no longer in contact with the drug. A two-component regulatory system designated ParR-ParS plays a major role in adaptive resistance induced by cationic peptides. In the presence of cationic peptides, ParR-ParS activates the lipopolysaccharide modification operon (arnBCADTEF) leading to increased resistance in polymyxins and aminoglycosides. The bactericidal kinetics related to adaptive resistance have important clinical implications and provide a rationale for administering cationic antibiotics in larger initial and longer interval bolus dosing. A better understanding of this phenomenon and the molecular mechanisms responsible will be essential not only for optimum use of cationic antibiotics but also for developing new agents with ability to counteract the detrimental effects of adaptive resistance and thus enhance the therapeutic efficacy of polycationic compounds. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  17. ORF Alignment: NC_006856 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available |AAW78928.1| neomycin phosphotransferase [Cloning and ... Tn7 delivery vec... resistance protein ... [Transposon delivery vector pUTkm1] gb|AAS99551.1| ... kanamycin resis... ... protein [Transposon delivery vector pUTKm] ... gb|AAA88337.1| aminoglycoside 3'-phosphotransferase...ing vector ... pSCANS-3-BNL] dbj|BAD07405.1| kanamycin resistance ...

  18. Therapeutic drug monitoring of antimicrobials.

    Science.gov (United States)

    Balakrishnan, Indran; Shorten, Robert J

    2016-05-01

    As pathology services become more centralized and automated, the measurement of therapeutic antimicrobial drugs concentrations is increasingly performed in clinical biochemistry or 'blood science' laboratories. This review outlines key groups of antimicrobial agents: aminoglycosides, glycopeptides, antifungal agents and antituberculosis agents, their role in managing infectious diseases, and the reasons why serum concentration measurement is important. © The Author(s) 2016.

  19. The Presence of aac (6 ' Ie / aph (2 ", aph (3' - IIIa1, ant (4 ' - Ia1 Genes and Determining Methicillin Resistance in Staphylococcus Epidermidis and Staphylococcus Saprophyticus Strains Isolated from Clinical Specimens

    Directory of Open Access Journals (Sweden)

    Mohammad Bokaeian

    2017-02-01

    Full Text Available Abstract Background: Aminoglycosides are used as antibiotics in combination with beta-lactamas for many treatments of staphylococcal infections. Development of resistance in resistant strains can be done by enzymes produced by effective genes that cause the destruction of aminoglycoside antibiotics. The aim of this study was to investigate the prevalence of the aac (6 ' Ie / aph (2 ", aph (3' - IIIa1, ant (4 ' - Ia1 genes and mecA in staphylococcus strains which play an effective part in the resistance of aminoglycosides. Materials and Methods: in this descriptive cross-sectional observation, 113 clinical samples including 68 isolate of Staphylococcus epidermidis and 45 isolate of Staphylococcus saprophyticus of 459 clinical samples were identified by biochemical and molecular tests. The antibiotic susceptibility pattern of isolates was determined using MIC method by E-test strips. Then, to determine the presence of genes responsible for resistance to aminoglycosides, gene-specific primers were used. Results: Of 68 isolates obtained from saprophyticus Staphylococcus aureus, 39isolates(57.35% were mecA gene. As well, 13 isolates (19.11% have aac (6 ' Ie / aph (2 " gene, 9 isolates (13.23% have aph (3' - IIIa1 gene and 7 isolates (7.3% have ant (4 ' - Ia1 gene. Of 45 isolates of Staphylococcus saprophyticus, 23 isolates(51.11% have mecA genes, 8 isolates (17.77% have aac (6' Ie / aph (2 " gene, 4 isolates (8/8% have aph (3 ' - IIIa1 gene and 2 isolates (4.4% have gene ant (4' - Ia1 gen. Conclusion: Statistical analysis showed that the prevalence of aminoglycoside genes is more among strains resistant to methicillin and this would suggest that methicillin-resistant strains are easy situation for the acquisition of resistance to other antibiotics.

  20. [Emergence of high-level resistance to gentamicin and streptomycin in Streptococcus agalactiae in Buenos Aires, Argentina].

    Science.gov (United States)

    Villar, Hugo Edgardo; Jugo, Mónica Beatriz

    2013-06-01

    Streptococcus agalactiae has become recognized as a cause of serious illness in newborns, pregnant women, and adults with chronic medical conditions. Optimal antimicrobial therapy for serious infections requires the use of synergistic combinations of a cell wall-active agent, such as a penicillin, with an aminoglycoside, which results in bactericidal activity against this organism. The synergistic effect is eliminated by the acquisition of high-level resistance (HLR) to aminoglycosides. The aim of our study was to determine the prevalence of HLR to gentamicin (GEN) and streptomycin (EST).The ability to detect HLR using a standard agar screen plate and high-content discs was investigated. This study was conducted with 141 strains of S. agalactiae isolated from vaginal and rectal swabs of pregnant women at term. Minimum inhibitory concentrations (MICs) to GEN and STR were determined by the E-test method. Disks of GEN (120 μg) and STR (300 μg) were used to detect HLR. Agar screening plates were performed with GEN 100 mg/L, GEN 500 mg/L and STR 2000 mg/L. The HLR to GEN and STR was detected in 13.5% and 16.3% of the isolates respectively. Among 141 strains, 7.8% were simultaneously resistant to GEN and STR. With 120-μg GEN and 300-μg STR disks, strains for which MICs were ≥ 512 mg/L and ≥ 1024 mg/L had no zones of inhibition. Isolates with inhibitory zones for GEN and STR of ≥13 mm showed a MICs ≤ 64 mg/L and ≤ 512 mg/L. All the screening plates were negative for these isolates. HLR to aminoglycosides was associated (83.9%) with resistance to erythromycin and/or clindamycin. This study highlights the emergence of strains with HLR to aminoglycosides. The disk-agar diffusion test performed with high-content aminoglycoside disks and screening plates can provide laboratories with a convenient and reliable method for detecting S. agalactiae isolates that are resistant to aminoglycoside-betalactam synergy.

  1. Synthesis and Antibacterial Activity of Antibiotic-Functionalized Graphite Nanofibers

    Directory of Open Access Journals (Sweden)

    Madeline Rotella

    2015-01-01

    Full Text Available Surface functionalization of nanomaterials is an area of current investigation that supports the development of new biomaterials for applications in biology and medicine. Herein we describe the synthesis, characterization, and antibacterial properties of the first examples of antibiotic-labeled graphitic carbon nanofibers (GCNFs covalently functionalized with aminoglycoside and quinolone antibiotics. Ruthenium tetroxide oxidation of herringbone GCNFs gave higher amounts of surface carboxyl groups than previous methods. These carboxyl groups served as sites of attachment for antibiotics by acyl substitution. Bioassay of these novel, functionalized GCNFs using serial dilution and optical density methods demonstrated that antibiotic-labeled GCNFs possess significant antibacterial activity against Pseudomonas aeruginosa. The activity we observe for aminoglycoside-functionalized GCNFs suggests a membranolytic mechanism of action.

  2. An international multicenter study of antimicrobial consumption and resistance in Staphylococcus aureus isolates from 15 hospitals in 14 countries

    DEFF Research Database (Denmark)

    Westh, Henrik Torkil; Zinn, Christina Scheel; Rosdahl, Vibeke Thamdrup

    2004-01-01

    Antibiotic consumption during 1996 was measured in 15 large hospitals from 14 countries and 3000 consecutive Staphylococcus aureus samples were collected, allowing calculation of local resistance rates and typing of isolates. Antibiotic consumption data were converted to defined daily doses (DDD...... of therapeutical subgroups of antimicrobials varied significantly between hospitals. A positive correlation was found between S. aureus resistance to methicillin (MRSA) and consumption of beta-lactam combinations, between resistance to quinolones and consumption of beta-lactam combinations and carbapenems...... and resistance to aminoglycosides and consumption of beta-lactam combinations. The consumption of beta-lactamase-sensitive antibiotics was negatively correlated to resistance to methicillin, quinolones, and aminoglycosides. Usage of the different antimicrobial therapeutical subgroups was also correlated...

  3. Low efficacy of tobramycin in experimental Staphylococcus aureus endocarditis

    DEFF Research Database (Denmark)

    Lerche, C. J.; Christophersen, L. J.; Trøstrup, H.

    2015-01-01

    The empiric treatment of infective endocarditis (IE) varies widely and, in some places, a regimen of penicillin in combination with an aminoglycoside is administered. The increasing incidence of Staphylococcus aureus IE, poor tissue penetration by aminoglycosides and low frequency of penicillin...... into untreated (n = 22) or tobramycin-treated (n = 13) groups. The treatment group received tobramycin once-daily. Animals were evaluated at 1 day post infection (DPI), 2 DPI or 3 DPI. Quantitative bacteriology and cytokine expression were measured for valves, myocardium and serum. A decrease of bacterial load...... was observed at 2 DPI (p ≤ 0.001) but not at 3 DPI. Tobramycin as functional monotherapy only reduced bacterial load and inflammation transiently, and was insufficient in most cases of S. aureus IE....

  4. Catheter-related bacteremia caused by multidrug-resistant Leclercia adecarboxylata in a patient with breast cancer.

    Science.gov (United States)

    Shin, Gee-Wook; You, Myung-Jo; Lee, Hye-Soo; Lee, Chang-Seop

    2012-09-01

    We report a multidrug-resistant strain of Leclercia adecarboxylata responsible for catheter-related bacteremia in a 47-year-old female with breast cancer. The isolated strain was resistant to several β-lactams, aminoglycosides, and folate pathway inhibitors and harbored bla(TEM-1) and bla(CTX-M) group 1 and intl1 genes (dfrA12-orfF-aadA2) as genetic determinants for resistance. Based on a review of the L. adecarboxylata literature, there have been only 4 reports of antibiotic-resistant strains. To our knowledge, this is the first report of an L. adecarboxylata strain with simultaneous resistance to β-lactams, aminoglycosides, and sulfonamides.

  5. The spatial profiles and metabolic capabilities of microbial populations impact the growth of antibiotic-resistant mutants

    Science.gov (United States)

    Kaushik, Karishma S.; Ratnayeke, Nalin; Katira, Parag; Gordon, Vernita D.

    2015-01-01

    Antibiotic resistance adversely affects clinical and public health on a global scale. Using the opportunistic human pathogen Pseudomonas aeruginosa, we show that increasing the number density of bacteria, on agar containing aminoglycoside antibiotics, can non-monotonically impact the survival of antibiotic-resistant mutants. Notably, at high cell densities, mutant survival is inhibited. A wide range of bacterial species can inhibit antibiotic-resistant mutants. Inhibition results from the metabolic breakdown of amino acids, which results in alkaline by-products. The consequent increase in pH acts in conjunction with aminoglycosides to mediate inhibition. Our work raises the possibility that the manipulation of microbial population structure and nutrient environment in conjunction with existing antibiotics could provide therapeutic approaches to combat antibiotic resistance. PMID:25972434

  6. Identification of strain harboring both aac(6')-Ib and aac(6')-Ib-cr variant simultaneously in Escherichia coli and Klebsiella pneumoniae.

    Science.gov (United States)

    Kim, Yun-Tae; Jang, Ji-Hyun; Kim, Hyun-Chul; Kim, Hyogyeong; Lee, Kyoung-Ryul; Park, Kyung Sun; Lee, Hee-Joo; Kim, Young-Jin

    2011-04-01

    The aac(6')-Ib gene is the most prevalent gene that encodes aminoglycoside-modifying enzymes and confers resistance to tobramycin, kanamycin, and amikacin. The aac(6')-Ib-cr variant gene can induce resistance against aminoglycoside and fluoroquinolone simultaneously. Two main methods, sequence analysis and the restriction enzyme method, can detect the aac(6')-Ib-cr variant in clinical strains. We collected the 85 strains that were believed to be aac(6')-Ib positive from clinical isolates. Among them, 38 strains were the wild-type; the remaining 47 strains were the aac(6')-Ib-cr variant. Of these 47 strains, 19 simultaneously harbored aac(6')-Ib and aac(6')-Ib-cr. Our study aims to report the characteristics of the 19 strains that simultaneously harbored both genes. This study is the first investigation published in Korea of strains that included both aac(6')-Ib and aac(6')-Ib-cr variant.

  7. Potential roles for DNA replication and repair functions in cell killing by streptomycin.

    Science.gov (United States)

    Humayun, M Zafri; Ayyappan, Vasudevan

    2013-09-01

    The aminoglycoside streptomycin binds to ribosomes to promote mistranslation and eventual inhibition of translation. Streptomycin kills bacteria, whereas many other non-aminoglycoside inhibitors of translation do not. Because mistranslation is now known to affect DNA replication, we asked if hydroxyurea, a specific inhibitor of DNA synthesis, affects killing, and find that hydroxyurea significantly attenuates killing by streptomycin. We find that the hydroxyl radical scavengers d-mannitol and thiourea have either no effect or only a modest protective effect. The iron chelator 2,2'-dipyridyl eliminated killing by streptomycin, but further investigation revealed that it blocks streptomycin uptake. Prior treatment of cells with low-levels of methyl methanesulfonate to induce the adaptive response to alkylation leads to a significant attenuation of killing, which, together with the hydroxyurea effect, suggests roles for DNA replication and repair functions in cell killing by streptomycin. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Crystal structure of the bacterial ribosomal decoding site complexed with amikacin containing the gamma-amino-alpha-hydroxybutyryl (haba) group.

    Science.gov (United States)

    Kondo, Jiro; François, Boris; Russell, Rupert J M; Murray, James B; Westhof, Eric

    2006-08-01

    Amikacin is the 4,6-linked aminoglycoside modified at position N1 of the 2-deoxystreptamine ring (ring II) by the L-haba group. In the present study, the crystal structure of a complex between oligonucleotide containing the bacterial ribosomal A site and amikacin has been solved at 2.7 A resolution. Amikacin specifically binds to the A site in practically the same way as its parent compound kanamycin. In addition, the L-haba group interacts with the upper side of the A site through two direct contacts, O2*...H-N4(C1496) and N4*-H...O6(G1497). The present crystal structure shows how the introduction of the L-haba group on ring II of aminoglycoside is an effective mutation for obtaining a higher affinity to the bacterial A site.

  9. 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.

  10. 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

  11. Radioimmunoassay, acetylating radio-enzymatic assay, and microbioassay of gentamicin: a comparative study

    International Nuclear Information System (INIS)

    Stevens, P.; Young, L.S.; Hewitt, W.L.

    1975-01-01

    Gentamicin is an aminoglycoside antibiotic widely used to treat gram-negative bacillary infections. Because it has a low therapeutic index, monitoring of serum levels may help to insure adequacy of dosage and avoid toxicity. Microbiological assays are relatively slow and can be complicated by the presence of other antimicrobials. Radioimmunoassay (RIA) and acetylating radio-enzymatic assay (ARA) are new methods for gentamicin assay which offer the following advantages: rapidity (less than 3 hours); no interference by other antibiotics; RIA is extremely sensitive and ARA is versatile (being useful in the measurement of other aminoglycosides). Correlation coefficients determined by linear regression analysis of assays on 36 patient samples performed in duplicate on 2 different days demonstrated no significant difference in measurement of gentamicin by each of the methods. Factors such as numbers of specimens, cost, and time involved will affect the decision of the method to be applied in individual laboratories. (U.S.)

  12. AFRRI Reports Second Quarter, April-June 1991

    Science.gov (United States)

    1991-07-01

    chosen after bacteria generally involves the use of aminoglycosides in preliminary data showed that the animals became suscepti- combination with beta...the infection within the Redden, B. J. Bamberger, J. G. Bartlett. R. Saral, and P. J. body. Burke. 1987; Oral norfloxacin for prevention of gram...25] and twice with chloroform. The combined extracts were dried under nitrogen and dissolved in chloroform. Both the control MATERIALS AND METHODS

  13. Draft genome sequence of a GES-5-producing Serratia marcescens isolated in southern Brazil

    Directory of Open Access Journals (Sweden)

    Carolina Silva Nodari

    Full Text Available Abstract Serratia marcescens is a Gram-negative rod intrinsically resistant to polymyxins and usually associated with wound, respiratory and urinary tract infections. The whole genome of the first GES-5-producing S. marcescens isolated from a Brazilian patient was sequenced using Ion Torrent PGM System. Besides blaGES-5, we were able to identify genes encoding for other β-lactamases, for aminoglycoside modifying enzymes and for an efflux pump to tetracyclines.

  14. 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.

  15. Heterogeneity of plasmids determining high-level resistance to gentamicin in clinical isolates of Streptococcus faecalis.

    OpenAIRE

    Zervos, M J; Mikesell, T S; Schaberg, D R

    1986-01-01

    Between November 1981 and October 1984, 48 of 3,458 clinical isolates of Streptococcus faecalis at the University of Michigan Hospital showed high-level (greater than 2,000 micrograms/ml) resistance to gentamicin, as well as to all other clinically available aminoglycosides. Thirteen percent of clinical isolates in the University of Michigan Hospital currently demonstrate this level of resistance. Transfer of resistance to a plasmid-free streptococcal recipient was observed in filter matings ...

  16. DOWN-STREAM SPATIAL DISTRIBUTION OF ANTIBIOTIC RESISTANCE TRAITS ALONG METAL CONTAMINATED STREAM REACHES

    Energy Technology Data Exchange (ETDEWEB)

    Tuckfield, C; J V Mcarthur (NOEMAIL), J

    2007-04-16

    Sediment bacteria samples were collected from three streams in South Carolina, two contaminated with multiple metals (Four Mile Creek and Castor Creek), one uncontaminated (Meyers Branch), and another metal contaminated stream (Lampert Creek) in northern Washington State. Growth plates inoculated with Four Mile Creek sample extracts show bacteria colony growth after incubation on plates containing either one of two aminoglycosides (kanamycin or streptomycin), tetracycline or chloramphenocol. This study analyzes the spatial pattern of antibiotic resistance in culturable sediment bacteria in all four streams that may be due to metal contamination. We summarize the two aminoglycoside resistance measures and the 10 metals concentrations by Principal Components Analysis. Respectively, 63% and 58% of the variability was explained in the 1st principal component of each variable set. We used the respective multivariate summary metrics (i.e. 1st principal component scores) as input measures for exploring the spatial correlation between antibiotic resistance and metal concentration for each stream reach sampled. Results show a significant and negative correlation between metals scores versus aminoglycoside resistance scores and suggest that selection for metal tolerance among sediment bacteria may influence selection for antibiotic resistance differently than previously supposed.. In addition, we borrow a method from geostatistics (variography) wherein a spatial cross-correlation analysis shows that decreasing metal concentrations scores are associated with increasing aminoglycoside resistance scores as the separation distance between sediment samples decreases, but for contaminated streams only. Since these results were counter to our initial expectation and to other experimental evidence for water column bacteria, we suspect our field results are influenced by metal bioavailability in the sediments and by a contaminant promoted interaction or ''cocktail effect

  17. Potentiation of Chemical Ototoxicity by Noise

    OpenAIRE

    Steyger, Peter S.

    2009-01-01

    High-intensity and/or prolonged exposure to noise causes temporary or permanent threshold shifts in auditory perception. Occupational exposure to solvents or administration of clinically important drugs, such as aminoglycoside antibiotics and cisplatin, also can induce permanent hearing loss. The mechanisms by which these ototoxic insults cause auditory dysfunction are still being unraveled, yet they share common sequelae, particularly generation of reactive oxygen species, that ultimately le...

  18. Prevalence of qnr and aac(6')-Ib-cr Genes in Clinical Isolates of Klebsiella Pneumoniae from Imam Hussein Hospital in Tehran.

    Science.gov (United States)

    Eftekhar, Fereshteh; Seyedpour, Seyed Mohsen

    2015-11-01

    Plasmid mediated quinolone resistance (PMQR) has been shown to play an important role in resistance not only to quinolones, but also β-lactams and aminoglycosides. In fact, qnr genes are frequently carried along with β-lactamase determinants on the same plasmids. We studied the prevalence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes among quinolone and cephalosporin resistant clinical isolates of Klebsiella pneumoniae (K. pneumoniae), as well as the association between PMQR genes with resistance to quinolones, cephalosporins and aminoglycosides. The study was conducted on 79 K. pneumoniae clinical isolates collected from Imam Hussein hospital in Tehran between July 2010 and January 2011, based on their resistance to quinilones and cephalosporins. Antibacterial susceptibility was determined to 15 antibiotics by disc diffusion. Presence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes were investigated using specific primers and PCR. Of the 79 K. pneumoniae isolates, 47 (59.5%) carried the PMQR determinants. Among these, 42 (89.4%) carried aac(6')-Ib-cr of which, 21 (50%) also harbored qnrB. Three isolates carried qnrB alone, two (4.2%) harbored qnrS and none had qnrA. Resistance to aminoglycosides and cephalosporins was significantly higher in the isolates carrying both qnrB and aac(6')-Ib-cr genes compared to aac(6')-Ib-cr alone. This study showed a high prevalence of aac(6')-Ib-cr and qnrB genes among the Iranian K. pneumoniae clinical isolates as well as co-carriage of the two genes. There was a significant association between qnrB gene carriage and resistance to quinolones, cephalosporins, and aminoglycosides.

  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. Comparison Between the Polymyxins and Gentamicin in Preventing Endotoxin-Induced Intravascular Coagulation and Leukopenia

    Science.gov (United States)

    Corrigan, James J.; Bell, Bobbie M.

    1971-01-01

    Three antimicrobial agents were evaluated as to their ability to neutralize the toxic effects of endotoxin in rabbits. These consisted of two cyclic polypeptides, polymyxin B sulfate and colymycin M (sodium colistimethate), and an aminoglycoside, gentamicin sulfate. Polymyxin B regularly prevented endotoxin-induced leukopenia, thrombocytopenia, and disseminated intravascular coagulation. Colymycin M had similar activity but was not as effective as polymyxin B. Gentamicin demonstrated no neutralizing ability in this study. PMID:4343409

  1. Neomycin B inhibits splicing of the td intron indirectly by interfering with translation and enhances missplicing in vivo.

    Science.gov (United States)

    Waldsich, C; Semrad, K; Schroeder, R

    1998-12-01

    The aminoglycoside antibiotic neomycin B inhibits translation in prokaryotes and interferes with RNA-protein interactions in HIV both in vivo and in vitro. Hitherto, inhibition of ribozyme catalysis has only been observed in vitro. We therefore monitored the activity of neomycin B and several other aminoglycoside antibiotics on splicing of the T4 phage thymidylate synthase (td) intron in vivo. All antibiotics tested inhibited splicing, even chloramphenicol, which does not inhibit splicing in vitro. Splicing of the td intron in vivo requires translation for proper folding of the pre-mRNA. In the absence of translation, two interactions between sequences in the upstream exon and the 5' and 3' splice sites trap the pre-mRNA in splicing-incompetent conformations. Their disruption by mutations rendered splicing less dependent on translation and also less sensitive to neomycin B. Intron splicing was affected by neither neomycin B nor gentamicin in Escherichia coli strains carrying antibiotic-resistance genes that modify the ribosomal RNA. Taken together, this demonstrates that in vivo splicing of td intron is not directly inhibited by aminoglycosides, but rather indirectly by their interference with translation. This was further confirmed by assaying splicing of the Tetrahymena group I intron, which is inserted in the E. coli 23 S rRNA and, thus, not translated. Furthermore, neomycin B, paromomycin, and streptomycin enhanced missplicing in antibiotic-sensitive strains. Missplicing is caused by an alternative structural element containing a cryptic 5' splice site, which serves as a substrate for the ribozyme. Our results demonstrate that aminoglycoside antibiotics display different effects on ribozymes in vivo and in vitro.

  2. Identification of clinically antibiotic resistant genes Aac(3-IIa and Aac(6’-Ib in wastewater samples by multiplex PCR

    Directory of Open Access Journals (Sweden)

    Naser Samadi

    2015-06-01

    Full Text Available Background: Aminoglycoside antibiotics are widely used in medical centers, particularly to treat infections. The resistance developed against these agents is a huge concern in health care. A number of researchers have reported that hospital and municipal wastewaters are among the most important dissemination sources of these agent into the environment. Some, however, do not agree with this opinion. In the present study, the prevalence of aminoglycoside resistance genes was investigated in raw and effluent wastewater from hospital and municipal wastewater treatment plants. Methods: To conduct this descriptive-analytical study, 30 samples were taken according to sampling principles and cold cycle and transferred to the molecular laboratory. DNA was extracted by the freeze-thaw method using a kit (Promega. The genes aac(3-IIa and aac(6’-Ib which code aminoglycoside resistance were examined in this study. Results: The results indicated that the studied genes are present in 35% of urban and hospital wastewaters, and their frequency percentage is higher in hospital wastewater (52% than urban wastewater (48%. The studied genes were identified in 61% of raw hospital wastewater samples; however, they were not detected in the output wastewater from the studied treatment plants. Conclusion: Although, the studied genes were not detected in the final effluent, there is a high potential for their release into the environment. The current study demonstrated that the coding genes of aminoglycoside antibiotic resistance are present in raw urban and hospital wastewaters. In the case of improper exploitation of wastewater treatment plants, the output water can contaminate other environmental sections, such as soil and water resources, and result in the emission of these contaminants.

  3. Class 1 Integron-Borne, Multiple-Antibiotic Resistance Encoded by a 150-Kilobase Conjugative Plasmid in Epidemic Vibrio cholerae O1 Strains Isolated in Guinea-Bissau

    OpenAIRE

    Dalsgaard, Anders; Forslund, Anita; Petersen, Andreas; Brown, Derek J.; Dias, Francisco; Monteiro, Serifo; Mølbak, Kåre; Aaby, Peter; Rodrigues, Amabelia; Sandström, Anita

    2000-01-01

    In the 1996–1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality ...

  4. Extremely low penetrance of deafness associated with the mitochondrial 12S rRNA mutation in 16 Chinese families: Implication for early detection and prevention of deafness

    International Nuclear Information System (INIS)

    Dai Pu; Liu Xin; Han Dongyi; Qian Yaping; Huang Deliang; Yuan Huijun; Li Weiming; Yu Fei; Zhang Ruining; Lin Hongyan; He Yong; Yu Youjun; Sun Quanzhu; Qin Huaiyi; Li Ronghua; Zhang Xin; Kang Dongyang; Cao Juyang; Young Wieyen; Guan Minxin

    2006-01-01

    Mutations in mitochondrial DNA (mtDNA) have been found to be associated with sensorineural hearing loss. We report here the clinical, genetic, and molecular characterization of 16 Chinese pedigrees (a total of 246 matrilineal relatives) with aminoglycoside-induced impairment. Clinical evaluation revealed the variable phenotype of hearing impairment including audiometric configuration in these subjects, although these subjects share some common features: being bilateral and sensorineural hearing impairment. Strikingly, these Chinese pedigrees exhibited extremely low penetrance of hearing loss, ranging from 4% to 18%, with an average of 8%. In particular, nineteen of 246 matrilineal relatives in these pedigrees had aminoglycoside-induced hearing loss. Mutational analysis of the mtDNA in these pedigrees showed the presence of homoplasmic 12S rRNA A1555G mutation, which has been associated with hearing impairment in many families worldwide. The extremely low penetrance of hearing loss in these Chinese families carrying the A1555G mutation strongly supports the notion that the A1555G mutation itself is not sufficient to produce the clinical phenotype. Children carrying the A1555G mutation are susceptible to the exposure of aminoglycosides, thereby inducing or worsening hearing impairment, as in the case of these Chinese families. Using those genetic and molecular approaches, we are able to diagnose whether children carry the ototoxic mtDNA mutation. Therefore, these data have been providing valuable information and technology to predict which individuals are at risk for ototoxicity, to improve the safety of aminoglycoside therapy, and eventually to decrease the incidence of deafness

  5. Burkholderia humptydooensis sp. nov., A Burkholderia thailandensis-Like Species and the Fifth Member of the pseudomallei Complex

    Science.gov (United States)

    2016-06-02

    to ceftazidime, imipenem, trimethoprim/sulfamethoxazole, and doxycycline, 179 whereas a resistance to amoxicillin /clavulanic acid was observed... resistant to aminoglycosides and 307 amoxicillin /clavulanic acid, but susceptible to trimethoprim/sulfmethoxazole, doxycycline, 308 imipenem, and...dilution of the following 160 antibiotics: amoxicillin /clavulanic acid (0.5–64/0.25–32 mg/L), ceftazidime (0.5–64 mg/L), 161 imipenem (0.25–32 mg/L

  6. Antibiotic rezistance genes in soil actinobacteria

    OpenAIRE

    Patrmanová, Tereza

    2016-01-01

    Actinobacteria are important members of the soil ecosystems, where they are involved in organic matter decomposition. It is worth mentioning that their secondary metabolism allows them to produce a variety of different compounds. These compounds include antibiotics, among them aminoglycosides have a place in clinical practice. These antibiotics are significant due to a broad spectrum of activities against both gram-negative and gram-positive bacteria. However, their use currently carries a ri...

  7. Structure and Function of APH(4)-Ia, a Hygromycin B Resistance Enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Stogios, Peter J.; Shakya, Tushar; Evdokimova, Elena; Savchenko, Alexei; Wright, Gerard D. (Toronto); (McMaster U.)

    2011-11-18

    The aminoglycoside phosphotransferase (APH) APH(4)-Ia is one of two enzymes responsible for bacterial resistance to the atypical aminoglycoside antibiotic hygromycin B (hygB). The crystal structure of APH(4)-Ia enzyme was solved in complex with hygB at 1.95 {angstrom} resolution. The APH(4)-Ia structure adapts a general two-lobe architecture shared by other APH enzymes and eukaryotic kinases, with the active site located at the interdomain cavity. The enzyme forms an extended hydrogen bond network with hygB primarily through polar and acidic side chain groups. Individual alanine substitutions of seven residues involved in hygB binding did not have significant effect on APH(4)-Ia enzymatic activity, indicating that the binding affinity is spread across a distributed network. hygB appeared as the only substrate recognized by APH(4)-Ia among the panel of 14 aminoglycoside compounds. Analysis of the active site architecture and the interaction with the hygB molecule demonstrated several unique features supporting such restricted substrate specificity. Primarily the APH(4)-Ia substrate-binding site contains a cluster of hydrophobic residues that provides a complementary surface to the twisted structure of the substrate. Similar to APH(2{double_prime}) enzymes, the APH(4)-Ia is able to utilize either ATP or GTP for phosphoryl transfer. The defined structural features of APH(4)-Ia interactions with hygB and the promiscuity in regard to ATP or GTP binding could be exploited for the design of novel aminoglycoside antibiotics or inhibitors of this enzyme.

  8. Effect of oral activated charcoal on tobramycin clearance.

    Science.gov (United States)

    Davis, R L; Koup, J R; Roon, R A; Opheim, K E; Smith, A N

    1988-01-01

    To evaluate the effect of activated charcoal on aminoglycoside pharmacokinetics, six healthy volunteers received tobramycin intravenously with and without multiple oral doses of activated charcoal. Activated charcoal did not have a statistically significant effect on any pharmacokinetic parameter. We conclude that activated charcoal does not enhance tobramycin clearance in subjects with normal renal function when concentrations in serum are within the therapeutic range. PMID:3364947

  9. Efflux-mediated fluoroquinolone resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7: identification of a novel MexS variant involved in upregulation of the mexEF-oprN multidrug efflux operon

    OpenAIRE

    Morita, Yuji; Tomida, Junko; Kawamura, Yoshiaki

    2015-01-01

    The emergence of multidrug-resistant Pseudomonas aeruginosa has become a serious problem in medical settings. P. aeruginosa clinical isolate PA7 is resistant to fluoroquinolones, aminoglycosides, and most β-lactams but not imipenem. In this study, enhanced efflux-mediated fluoroquinolone resistance of PA7 was shown to reflect increased expression of two resistance nodulation cell division (RND) -type multidrug efflux operons, mexEF-oprN and mexXY-oprA. Such a clinical isolate has rarely been ...

  10. 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 ...

  11. Characterization of class 1 integrons associated with R-plasmids in clinical Aeromonas salmonicida isolates from various geographical areas

    DEFF Research Database (Denmark)

    Schmidt, A.S.; Bruun, Morten Sichlau; Larsen, J.L.

    2001-01-01

    sulphadiazine, trimethoprim and streptomycin resistances were invariably encoded by integrons. It thus appears that integron-encoded antibiotic resistance genes contribute substantially to the horizontal spread of antimicrobial resistance within this species, being associated with conjugative plasmids.......Class 1 integrons were found in 26 of 40 antibiotic-resistant isolates of the fish pathogen Aeromonas salmonicida from Northern Europe and North America. Three different dhfr genes, conferring trimethoprim resistance, and one ant(3 " )1a aminoglycoside resistance gene were identified as gene...

  12. Occurrence of antibiotics in pharmaceutical industrial wastewater, wastewater treatment plant and sea waters in Tunisia.

    Science.gov (United States)

    Tahrani, Leyla; Van Loco, Joris; Ben Mansour, Hedi; Reyns, Tim

    2016-04-01

    Antibiotics are among the most commonly used group of pharmaceuticals in human medicine. They can therefore reach surface and groundwater bodies through different routes, such as wastewater treatment plant effluents, surface runoff, or infiltration of water used for agricultural purposes. It is well known that antibiotics pose a significant risk to environmental and human health, even at low concentrations. The aim of the present study was to evaluate the presence of aminoglycosides and phenicol antibiotics in municipal wastewaters, sea water and pharmaceutical effluents in Tunisia. All analysed water samples contained detectable levels of aminoglycoside and phenicol antibiotics. The highest concentrations in wastewater influents were observed for neomycin and kanamycin B (16.4 ng mL(-1) and 7.5 ng mL(-1), respectively). Chloramphenicol was found in wastewater influents up to 3 ng mL(-1). It was observed that the waste water treatment plants were not efficient in completely removing these antibiotics. Chloramphenicol and florfenicol were found in sea water samples near aquaculture sites at levels up to, respectively, 15.6 ng mL(-1) and 18.4 ng mL(-1). Also aminoglycoside antibiotics were found near aquaculture sites with the highest concentration of 3.4 ng mL(-1) for streptomycin. In pharmaceutical effluents, only gentamycin was found at concentrations up to 19 ng mL(-1) over a sampling period of four months.

  13. Covalently linked kanamycin - Ciprofloxacin hybrid antibiotics as a tool to fight bacterial resistance.

    Science.gov (United States)

    Shavit, Michal; Pokrovskaya, Varvara; Belakhov, Valery; Baasov, Timor

    2017-06-01

    To address the growing problem of antibiotic resistance, a set of 12 hybrid compounds that covalently link fluoroquinolone (ciprofloxacin) and aminoglycoside (kanamycin A) antibiotics were synthesized, and their activity was determined against both Gram-negative and Gram-positive bacteria, including resistant strains. The hybrids were antagonistic relative to the ciprofloxacin, but were substantially more potent than the parent kanamycin against Gram-negative bacteria, and overcame most dominant resistance mechanisms to aminoglycosides. Selected hybrids were 42-640 fold poorer inhibitors of bacterial protein synthesis than the parent kanamycin, while they displayed similar inhibitory activity to that of ciprofloxacin against DNA gyrase and topoisomerase IV enzymes. The hybrids showed significant delay of resistance development in both E. coli and B. subtilis in comparison to that of component drugs alone or their 1:1 mixture. More generally, the data suggest that an antagonistic combination of aminoglycoside-fluoroquinolone hybrids can lead to new compounds that slowdown/prevent the emergence of resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Herbal therapy associated with antibiotic therapy: potentiation of the antibiotic activity against methicillin – resistant Staphylococcus aureus by Turnera ulmifolia L

    Directory of Open Access Journals (Sweden)

    Lima Edeltrudes O

    2009-05-01

    Full Text Available Abstract Background Staphylococcus genus is widely spread in nature being part of the indigenous microbiota of skin and mucosa of animal and birds. Some Staphylococcus species are frequently recognized as etiological agents of many animal and human opportunistic infections This is the first report testing the antibiotic resistance-modifying activity of Turnera ulmifolia against methicillin-resistant Staphylococcus aureus – MRSA strain. Methods In this study an ethanol extract of Turnera ulmifolia L. and chlorpromazine were tested for their antimicrobial activity alone or in combination with aminoglycosides against an MRSA strain. Results The synergism of the ethanol extract and aminoglycosides were verified using microdillution method. A synergistic effect of this extract on gentamicin and kanamycin was demonstrated. Similarly, a potentiating effect of chlorpromazine on kanamycin, gentamicin and neomycin, indicating the involvement of an efflux system in the resistance to these aminoglycosides. Conclusion It is therefore suggested that extracts from Turnera ulmifolia could be used as a source of plant-derived natural products with resistance-modifying activity, constituting a new weapon against the problem of bacterial resistance to antibiotics demonstrated in MRSA strains.

  15. Induction of Streptomycin Uptake in Resistant Strains of Escherichia coli

    Science.gov (United States)

    Höltje, Joachim-Volker

    1979-01-01

    Different streptomycin-resistant strains of Escherichia coli, including an R100 plasmid-carrying strain of E. coli W3110, the ribosomally resistant mutant SM10, and the spontaneous revertant from dependence to independence d1023, exhibited poor accumulation capacity for aminoglycoside antibiotics. This was due to a failure of these mutants to induce the general polyamine transport system that is utilized by streptomycin to enter the cell. It is shown that the aminoglycoside kanamycin, which is effective on these streptomycin-resistant strains, was capable of inducing the uptake of streptomycin, thus giving rise to streptomycin accumulation up to wild-type levels. Plasmid-determined resistance, which has been speculated to be the result of a blockage of the uptake system by modified antibiotic molecules, cannot be overcome by the induction of streptomycin transport. Increase in permeability of the antibiotic does not affect the susceptibility of the bacteria. It is shown that all of the antibiotic taken up was enzymatically modified. R-plasmid-conferred resistance to aminoglycosides is therefore explained by the inactivation of the antibiotic entering the bacterial cell. PMID:371542

  16. The importance of audiometric monitoring in patients with multidrug-resistant tuberculosis

    Directory of Open Access Journals (Sweden)

    Karla Anacleto de Vasconcelos

    Full Text Available Abstract INTRODUCTION: A total of 771 cases of multidrug-resistant tuberculosis (MDR-TB were reported in Brazil in 2014. Treatment of MDR-TB with aminoglycosides can produce serious side effects such as permanent and irreversible hearing loss, which occurs in 5-64% of cases, and severely compromise patient quality of life. The goal of this research was to evaluate auditory and vestibular side effects in patients treated for MDR-TB and to identify associations between these complaints and the type of aminoglycoside used. METHODS: We performed a retrospective review of 599 medical records from patients with MDR-TB who were treated at the Hélio Fraga/Fiocruz Reference Center between 2006 and 2010. Cases without auditory or vestibular complaints and patients who were not treated with aminoglycoside drugs were excluded from the study. RESULTS: Of 164 eligible cases, 55 (33.5% reported an auditory or vestibular complaint and medication was subsequently suspended, although hearing damage was not confirmed in all cases. Audiometric testing confirmed hearing loss in 11 (21.7% of 12 cases submitted for evaluation. Hearing loss related to ototoxicity was confirmed in 15 (62.5% cases. Tinnitus was significantly associated with the use of amikacin and streptomycin. CONCLUSIONS: Evaluations of ototoxicity symptoms were not usually reported in the routine care of patients with MDR-TB. Complaints of tinnitus were associated with amikacin and streptomycin use. These results require confirmation in future studies.

  17. 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.

  18. Measurement of total phospholipids in urine of patients treated with gentamicin.

    Science.gov (United States)

    Saunders, D A; Begg, E J; Kirkpatrick, C M; Yeo, J; Graham, G G; Bailey, R R

    1997-04-01

    The excretion of phospholipids in urine may be a marker of the early renal toxicity of the aminoglycoside antibiotics. Urinary phospholipids are formed in myeloid bodies which develop in the lysosomes of proximal tubules during treatment with the aminoglycosides, and overflow into the urine. Published assays were modified in order to measure the total phospholipid concentrations in human urine. Phospholipids were extracted from freeze-dried urine samples, digested in concentrated sulphuric acid, and the inorganic phosphorus content determined by complexing with ammonium molybdate and measuring the absorbance at 820 nm. Ten septicaemic patients treated with gentamicin for 5-7 days had significantly higher urine phospholipid concentrations than 10 healthy untreated control subjects (P < 0.0001). There was a negative linear relationship between phospholipid excretion and creatinine clearance (r2 = 0.71). In 34 patients with acute pyelonephritis, increased phospholipid concentrations were observed prior to treatment compared with healthy controls (P < 0.001) and did not alter during treatment with gentamicin. However, the phospholipid concentrations decreased significantly after treatment was completed (P < 0.03). These studies suggest that urinary phospholipids may indicate early aminoglycoside toxicity but with poor specificity, as many of the infections being treated may themselves be associated with phospholipiduria.

  19. 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

  20. Chemical Characterization and Cytoprotective Effect of the Hydroethanol Extract from Annona coriacea Mart. (Araticum)

    Science.gov (United States)

    Júnior, José G. A. S.; Coutinho, Henrique D. M.; Boris, Ticiana C. C.; Cristo, Janyketchuly S.; Pereira, Nara L. F.; Figueiredo, Fernando G.; Cunha, Francisco A. B.; Aquino, Pedro E. A.; Nascimento, Polyana A. C.; Mesquita, Francisco J. C.; Moreira, Paulo H. F.; Coutinho, Sáskia T. B.; Souza, Ivon T.; Teixeira, Gabriela C.; Ferreira, Najla M. N.; Farina, Eleonora O.; Torres, Cícero M. G.; Holanda, Vanderlan N.; Pereira, Vandbergue S.; Guedes, Maria I. F.

    2016-01-01

    Introduction: Annona coriacea Mart. (araticum) is a widely distributed tree in the cerrado. Its value is attributed principally to the consumption of its fruit which possesses a large nutritive potential. The objective was to identify the chemical profile and evaluate the antimicrobial and cytoprotective activity of the hydroethanol extract of A. coriacea Mart. (HEAC) leaves against the toxicity of mercury chloride. Materials and Methods: The characterization of components was carried out using high-performance liquid chromatography (HPLC). The minimum inhibitory concentration (MIC) was determined by microdilution method in broth with strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. For evaluation of the modulatory and cytoprotective activity of aminoglycoside antibiotics (gentamicin and amikacin) and mercury chloride (HgCl2), the substances were associated with the HEAC at subinhibitory concentrations (MIC/8). Results and Discussion: The HPLC analysis revealed the presence of flavonoids such as Luteolin (1.84%) and Quercetin (1.19%) in elevated concentrations. The HEAC presented an MIC ≥512 μg/mL and significant antagonistic action in aminoglycosides modulation, and it also showed cytoprotective activity to S. aureus (significance P < 0.0001) and E. coli (significance P < 0.05) bacteria against the mercury chloride heavy metal with significance, this action being attributed to the chelating properties of the flavonoids found in the chemical identification. Conclusions: The results acquired in this study show that the HEAC presents cytoprotective activity over the tested strains in vitro and can also present antagonistic effect when associated with aminoglycosides, reinforcing the necessity of taking caution when combining natural and pharmaceutical products. SUMMARY The hydroalcoholic extract of A. coriacea Mart. presents in vitro cytoprotective activity against the toxic effect of Hg. Abbreviations Used: HPLC-DAD: High

  1. Characterization of Acinetobacter baumannii clinical isolates carrying bla(OXA-23) carbapenemase and 16S rRNA methylase armA genes in Yemen.

    Science.gov (United States)

    Bakour, Sofiane; Alsharapy, Samer Ahmed; Touati, Abdelaziz; Rolain, Jean-Marc

    2014-12-01

    The aim of this study was to investigate the molecular support of resistance to carbapenems, aminoglycosides, and fluoroquinolones in Acinetobacter baumannii clinical isolates collected from Yemen hospital. Three A. baumannii were isolated in February 2013 from three patients hospitalized at Al-Thawra University Hospital in Sana'a, Yemen. Antibiotic susceptibility testing was performed using the disk diffusion and E-test methods. Carbapenemase production was carried out by the modified Hodge test (MHT) and imipenem-ethylenediaminetetraacetic acid (EDTA) methods. Carbapenem, aminoglycoside, and fluoroquinolone resistance determinants were studied by polymerase chain reaction and sequencing. The epidemiological relatedness of the three strains was studied using multilocus sequence typing (MLST). The isolates were resistant to almost all antibiotics tested with very high imipenem, amikacin, and ciprofloxacin minimum inhibitory concentrations (>32, >256, and >32 mg/L, respectively). The microbiological tests showed that the three A. baumannii were MHT positive, besides, the activity of β-lactamases was not inhibited by EDTA. All the three isolates contained the naturally occurring bla(OXA-51)-like gene and the bla(OXA-23)-like carbapenemase-encoding gene. The 16S rRNA methylase armA gene was detected in the three isolates. In addition, screening for genes encoding the aminoglycoside-modifying enzymes (AMEs) demonstrated that one isolate contained the acetyltransferase gene aac(6')-Ib. Fluoroquinolone resistance was associated with a single mutation Ser83Leu in the quinolone resistance determining region of the gyrA gene in all isolates. The MLST showed that the sequence type (ST) obtained corresponds to ST2 for the three strains. Here we report the first identification of multidrug-resistant A. baumannii isolates harboring the bla(OXA-23)-like gene, AMEs [aac(6')-Ib], and the 16S rRNA methylase (armA) in the Yemen hospital.

  2. In vivo characteristics of targeted drug-carrying filamentous bacteriophage nanomedicines

    Directory of Open Access Journals (Sweden)

    Vaks Lilach

    2011-12-01

    Full Text Available Abstract Background Targeted drug-carrying phage nanomedicines are a new class of nanomedicines that combines biological and chemical components into a modular nanometric drug delivery system. The core of the system is a filamentous phage particle that is produced in the bacterial host Escherichia coli. Target specificity is provided by a targeting moiety, usually an antibody that is displayed on the tip of the phage particle. A large drug payload is chemically conjugated to the protein coat of the phage via a chemically or genetically engineered linker that provides for controlled release of the drug after the particle homed to the target cell. Recently we have shown that targeted drug-carrying phage nanomedicines can be used to eradicate pathogenic bacteria and cultured tumor cells with great potentiation over the activity of the free untargeted drug. We have also shown that poorly water soluble drugs can be efficiently conjugated to the phage coat by applying hydrophilic aminoglycosides as branched solubility-enhancing linkers. Results With an intention to move to animal experimentation of efficacy, we tested anti-bacterial drug-carrying phage nanomedicines for toxicity and immunogenicity and blood pharmacokinetics upon injection into mice. Here we show that anti-bacterial drug-carrying phage nanomedicines that carry the antibiotic chloramphenicol conjugated via an aminoglycoside linker are non-toxic to mice and are greatly reduced in immunogenicity in comparison to native phage particles or particles to which the drug is conjugated directly and are cleared from the blood more slowly in comparison to native phage particles. Conclusion Our results suggest that aminoglycosides may serve as branched solubility enhancing linkers for drug conjugation that also provide for a better safety profile of the targeted nanomedicine.

  3. Single daily dosing of antibiotics: importance of in vitro killing rate, serum half-life, and protein binding.

    Science.gov (United States)

    Potel, G; Chau, N P; Pangon, B; Fantin, B; Vallois, J M; Faurisson, F; Carbon, C

    1991-10-01

    The relative importance of pharmacokinetic and pharmacodynamic parameters for the feasibility of a single daily dose (SDD) of antibiotics remains to be established. Therefore, we studied the relationship between in vitro bacteriological parameters (MIC, MBC, and killing rate [KR], defined as the reduction in the inoculum within 3 h), pharmacokinetic parameters (t1/2 and protein binding [PB], and in vivo antibacterial effect of a single antibiotic dose in an experimental rabbit model of Escherichia coli endocarditis. Nine antibiotics were investigated: two aminoglycosides, two quinolones, and five beta-lactams. For each drug, the minimal effective dose (MED) (in milligrams per kilogram) was defined as the lowest dose able to achieve a significant difference (P less than 0.05) of CFU in the vegetations in comparison with controls 24 h after a single intravenous injection. Aminoglycosides and quinolones had the lowest MEDs, followed by beta-lactams. Univariate regression analysis showed that KR was the major determinant of MED. A stepwise regression analysis showed that t1/2 significantly improved the predictive value of KR, while PB, MIC, and MBC did not. The final equation was MED = 1,586-238 KR-297 t1/2 (r = 0.90, P = 0.01). We concluded that the pharmacodynamic parameters (especially the high KR) of aminoglycosides and quinolones explained their low MEDs and might allow SDD. In contrast, the low KR of beta-lactams emphasized the critical importance of a long t1/2, as for ceftriaxone, allowing the use of this beta-lactam alone in SDD.

  4. Preparation of fluorescent labeled gentamicin as biological tracer and its characterization by liquid chromatography and high resolution mass spectrometry.

    Science.gov (United States)

    Woiwode, Ulrich; Sievers-Engler, Adrian; Lämmerhofer, Michael

    2016-03-20

    This work deals with the preparation of single-labeled bioconjugates of the antibiotic Gentamicin (GT) with the sulforhodamine-derived fluorescence dye Texas Red(®)-X (TR), its purification by high-performance liquid chromatography (HPLC) and its characterization by high-resolution mass spectrometry. Aminoglycosides such as GT are efficient antibiotics, but also problematic due to severe side effects such as nephro- and ototoxicity. Fluorescent labeled GT is used to visualize cellular uptake and distribution of the antibiotic to finally understand the mechanisms of serious adverse drug reactions. Pharmaceutically administered GT is a mixture of mainly four different components, which exhibit three (GT(C1)) or four (GT(C1a), GT(C2), GT(C2a)) primary amino functional groups which can be coupled with the labeling reagent TR. Thus, multiple labeling could be envisaged which was assumed to be detrimental for uptake studies by fluorescence imaging. The proposed synthesis aimed at preparation of single labeled product and together with the employed purification strategy indeed yielded single labeled GT as product. Analytical control of the reaction product was carried out by means of mass spectrometry (UHPLC-ESI-QTOF-MS/MS) to rule out over-labeling of GT, which would alter the physicochemical characteristics of GT and its cellular uptake significantly. Moreover, LC-MS/MS analysis gave valuable insights into structural diversity of single labeled products. Further, high-resolution MS and MS/MS spectra of underivatized GT are provided as well. The analytical information on preparation strategy and structure diversity is valuable for studies with a clinical focus on research of aminoglycoside toxicity. Furthermore, it is deemed to be useful for the development of LC-MS/MS assays for the determination of aminoglycosides or the fast screening of synthetic biology samples from biotechnological drug discovery. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Studying the Phenotypic and Genotypic Expression of Antibiotic Resistance in Campylobacter jejuni under Stress Conditions.

    Science.gov (United States)

    Efimochkina, N R; Stetsenko, V V; Bykova, I V; Markova, Yu M; Polyanina, A S; Aleshkina, A I; Sheveleva, S A

    2018-03-01

    Specific features for the development of resistance in Campylobacter jejuni strains were studied after treatment with antibiotics of 6 pharmacological groups. Populations of 18 native strains of C. jejuni (isolated from raw poultry products) and their subcultures (obtained after 2-3-fold stress exposures to antimicrobial agents in subinhibitory doses) were examined to evaluate the expression of phenotypic antibiotic resistance. Genotypic properties of strains were studied by the PCR with primers that detect the presence of genes for resistance to aminoglycosides (aphA-1, aphA-3, and aphA-7), tetracyclines (tetO), and quinolones (GZgyrA). The majority of test strains of C. jejuni exhibited a high resistance to nalidixic acid, ciprofloxacin, and tetracycline, which reached the maximum value after numerous passages. The expression of antibiotic resistance was greatest in the presence of nalidixic acid and tetracycline. Ciprofloxacin resistance of 33% strains, which were initially resistant to this antibiotic, was increased after 2-3-fold treatment. We revealed a high degree of correspondence between phenotypic and genotypic profiles of antibiotic resistance in food isolates of Campylobacter. One, two, or more genes of aphA were identified in 85% strains phenotypically resistant to aminoglycosides. The tetO gene was found nearly in all strains resistant to tetracycline. Studying the biofilm matrix in C. jejuni after culturing with antibiotics in subinhibitory doses showed that quinolones (particularly nalidixic acid) and tetracyclines potentiate the formation of biofilms and increase the tolerance of Campylobacter to stress exposures. The intensity of biofilm growth was shown to depend little on the effect of macrolides and aminoglycosides. Therefore, the presence of these agents in residual concentrations is associated with a lower risk for the development of antibiotic resistance in C. jejuni populations.

  6. Extremely low penetrance of hearing loss in four Chinese families with the mitochondrial 12S rRNA A1555G mutation

    International Nuclear Information System (INIS)

    Young Wieyen; Zhao Lidong; Qian Yaping; Wang Qiuju; Li Ning; Greinwald, John H.; Guan Minxin

    2005-01-01

    Mutations in mitochondrial DNA (mtDNA) have been found to be associated with sensorineural hearing loss. We report here the clinical, genetic, and molecular characterization of four Chinese pedigrees with aminoglycoside-induced and nonsyndromic hearing impairment. Clinical evaluation revealed the variable phenotype of hearing impairment including audiometric configuration in these subjects, although these subjects share some common features: bilateral and sensorineural hearing impairment. Strikingly, these Chinese pedigrees exhibited extremely low penetrance of hearing loss (5.2%, 4.8%, 4.2%, and 13.3%, respectively, and with an average 8% penetrance). In particular, four of all five affected matrilineal relatives of these pedigrees had aminoglycoside-induced hearing loss. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the distinct sets of mtDNA polymorphism, in addition to the identical homoplasmic A1555G mutation, associated with hearing impairment in many families from different genetic backgrounds. The fact that mtDNA of those pedigrees belonged to different haplogroups R9a, N9a, D4a, and D4 suggested that the A1555G mutation occurred sporadically and multiplied through evolution of the mtDNA in China. However, there was the absence of functionally significant mutations in tRNA and rRNAs or secondary LHON mutations in these Chinese families. These data imply that the nuclear background or/and mitochondrial haplotype may not play a significant role in the phenotypic expression of the A1555G mutation in these Chinese pedigrees. However, aminoglycoside appears to be a major modifier factor for the phenotypic manifestation of the A1555G mutation in these Chinese families

  7. Cell-specific accumulation patterns of gentamicin in the guinea pig cochlea.

    Science.gov (United States)

    Heinrich, Ulf-Rüdiger; Schmidtmann, Irene; Strieth, Sebastian; Helling, Kai

    2015-08-01

    Intratympanic gentamicin therapy has become a popular treatment modality for Ménière's disease (MD) through controlled elimination of vertigo spells caused by the balance organ. However, the known ototoxic properties of aminoglycosides lead to cochlear damage. In order to gain more information about cellular preferences for aminoglycoside accumulation within the cochlea, gentamicin was immuno histochemically localized by light microscopy in male guinea pigs 1 and 7 days after intratympanic application (n = 8 ears/incubation time). Differences in the gentamicin-specific cellular storage capacities were quantified by determination of the local immuno staining intensities. Gentamicin was detected in every cochlear cell type, but with spatiotemporal variability. One day after application, an intense staining reaction was found in all cell types except the spiral ganglion cells and the stria vascularis. Six days later, gentamicin staining intensities were additionally reduced in the nerve fibers and the spiral ligament. Statistic analysis revealed strong cellular associations in respect to aminoglycoside accumulation. Furthermore, associations with recorded hearing losses were identified comparing the cellular gentamicin content in the organ of Corti, in the stria vascularis, in the spiral ganglion cells and in fibrocytes of the Limbus. In the lateral wall, clear differences in cellular gentamicin accumulation were found between type I fibrocytes of the spiral ligament compared with basal and intermediate cells of the stria vascularis. This finding was unexpected as these three cell types belong to a well-developed gap-junction system which normally enables unhampered cell communication. Cellular differences in local gentamicin storage capacities, transport processes and inherent diffusion barriers are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Neomycin damage and regeneration of hair cells in both mechanoreceptor and electroreceptor lateral line organs of the larval Siberian sturgeon (Acipenser baerii).

    Science.gov (United States)

    Fan, Chunxin; Zou, Sha; Wang, Jian; Zhang, Bo; Song, Jiakun

    2016-05-01

    The lateral line found in some amphibians and fishes has two distinctive classes of sensory organs: mechanoreceptors (neuromasts) and electroreceptors (ampullary organs). Hair cells in neuromasts can be damaged by aminoglycoside antibiotics and they will regenerate rapidly afterward. Aminoglycoside sensitivity and the capacity for regeneration have not been investigated in ampullary organs. We treated Siberian sturgeon (Acipenser baerii) larvae with neomycin and observed loss and regeneration of sensory hair cells in both organs by labeling with DASPEI and scanning electron microscopy (SEM). The numbers of sensory hair cells in both organs were reduced to the lowest levels at 6 hours posttreatment (hpt). New sensory hair cells began to appear at 12 hpt and were regenerated completely in 7 days. To reveal the possible mechanism for ampullary hair cell regeneration, we analyzed cell proliferation and the expression of neural placodal gene eya1 during regeneration. Both cell proliferation and eya1 expression were concentrated in peripheral mantle cells and both increased to the highest level at 12 hpt, which is consistent with the time course for regeneration of the ampullary hair cells. Furthermore, we used Texas Red-conjugated gentamicin in an uptake assay following pretreatment with a cation channel blocker (amiloride) and found that entry of the antibiotic was suppressed in both organs. Together, our results indicate that ampullary hair cells in Siberian sturgeon larvae can be damaged by neomycin exposure and they can regenerate rapidly. We suggest that the mechanisms for aminoglycoside uptake and hair cell regeneration are conserved for mechanoreceptors and electroreceptors. J. Comp. Neurol. 524:1443-1456, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  9. Translational read-through as an alternative approach for ocular gene therapy of retinal dystrophies caused by in-frame nonsense mutations.

    Science.gov (United States)

    Nagel-Wolfrum, Kerstin; Möller, Fabian; Penner, Inessa; Wolfrum, Uwe

    2014-09-01

    The eye has become an excellent target for gene therapy, and gene augmentation therapy of inherited retinal disorders has made major progress in recent years. Nevertheless, a recent study indicated that gene augmentation intervention might not stop the progression of retinal degeneration in patients. In addition, for many genes, viral-mediated gene augmentation is currently not feasible due to gene size and limited packaging capacity of viral vectors as well as expression of various heterogeneous isoforms of the target gene. Thus, alternative gene-based strategies to stop or delay the retinal degeneration are necessary. This review focuses on an alternative pharmacologic treatment strategy based on the usage of translational read-through inducing drugs (TRIDs) such as PTC124, aminoglycoside antibiotics, and designer aminoglycosides for overreading in-frame nonsense mutations. This strategy has emerged as an option for up to 30-50% of all cases of recessive hereditary retinal dystrophies. In-frame nonsense mutations are single-nucleotide alterations within the gene coding sequence resulting in a premature stop codon. Consequently, translation of such mutated genes leads to the synthesis of truncated proteins, which are unable to fulfill their physiologic functions. In this context, application of TRIDs facilitates the recoding of the premature termination codon into a sense codon, thus restoring syntheses of full-length proteins. So far, clinical trials for non-ocular diseases have been initiated for diverse TRIDs. Although the clinical outcome is not analyzed in detail, an excellent safety profile, namely for PTC124, was clearly demonstrated. Moreover, recent data demonstrated sustained read-through efficacies of nonsense mutations causing retinal degeneration, as manifested in the human Usher syndrome. In addition, a strong retinal biocompatibility for PTC124 and designer aminoglycosides has been demonstrated. In conclusion, recent progress emphasizes the

  10. Antimicrobial resistance determinants in imipenem-nonsusceptible Acinetobacter calcoaceticus-baumannii complex isolated in Daejeon, Korea.

    Science.gov (United States)

    Sung, Ji Youn; Kwon, Kye Chul; Cho, Hye Hyun; Koo, Sun Hoe

    2011-10-01

    Members of the Acinetobacter calcoaceticus-baumannii (Acb) complex are important opportunistic bacterial pathogens and present significant therapeutic challenges in the treatment of nosocomial infections. In the present study, we investigated the integrons and various genes involved in resistance to carbapenems, aminoglycosides, and fluoroquinolones in 56 imipenem-nonsusceptible Acb complex isolates. This study included 44 imipenem-nonsusceptible A. baumannii, 10 Acinetobacter genomic species 3, and 2 Acinetobacter genomic species 13TU strains isolated in Daejeon, Korea. The minimum inhibitory concentrations (MICs) were determined by Etest. PCR and DNA sequencing were used to identify the genes that potentially contribute to each resistance phenotype. All A. baumannii isolates harbored the bla(OXA-51)-like gene, and 21 isolates (47.7%) co-produced OXA-23. However, isolates of Acinetobacter genomic species 3 and 13TU only contained bla(IMP-1) or bla(VIM-2). Most Acb complex isolates (94.6%) harbored class 1 integrons, armA, and/or aminoglycoside-modifying enzymes (AMEs). Of particular note was the fact that armA and aph(3')-Ia were only detected in A. baumannii isolates, which were highly resistant to amikacin (MIC(50)≥256) and gentamicin (MIC(50)≥1,024). In all 44 A. baumannii isolates, resistance to fluoroquinolones was conferred by sense mutations in the gyrA and parC. However, sense mutations in parC were not found in Acinetobacter genomic species 3 or 13TU isolates. Several differences in carbapenem, aminoglycoside, and fluoroquinolone resistance gene content were detected among Acb complex isolates. However, most Acb complex isolates (87.5%) possessed integrons, carbapenemases, AMEs, and mutations in gyrA. The co-occurrence of several resistance determinants may present a significant threat.

  11. Molecular structure and evolution of the conjugative multiresistance plasmid pRE25 of Enterococcus faecalis isolated from a raw-fermented sausage.

    Science.gov (United States)

    Teuber, Michael; Schwarz, Franziska; Perreten, Vincent

    2003-12-01

    Plasmid pRE25 from Enterococcus faecalis transfers resistances against kanamycin, neomycin, streptomycin, clindamycin, lincomycin, azithromycin, clarithromycin, erythromycin, roxithromycin, tylosin, chloramphenicol, and nourseothricin sulfate by conjugation in vitro to E. faecalis JH2-2, Lactococcus lactis Bu2, and Listeria innocua L19. Its nucleotide sequence of 50237 base pairs represents the largest, fully sequenced conjugative multiresistance plasmid of enterococci (Plasmid 46 (2001) 170). The gene for chloramphenicol resistance (cat) was identified as an acetyltransferase identical to the one of plasmid pIP501 of Streptococcus agalactiae. Erythromycin resistance is due to a 23S ribosomal RNA methyl transferase, again as found in pIP501 (ermB). The aminoglycoside resistance genes are packed in tandem as in transposon Tn5405 of Staphylococcus aureus: an aminoglycoside 6-adenyltransferase, a streptothricin acetyl transferase, and an aminoglycoside phosphotransferase.). Identical resistance genes are known from pathogens like Streptococcus pyogenes, S. agalactiae, S. aureus, Campylobacter coli, Clostridium perfringens, and Clostridium difficile. pRE25 is composed of a 30.5-kbp segment almost identical to pIP501. Of the 15 genes involved in conjugative transfer, 10 codes for putative transmembrane proteins (e.g. trsB, traC, trsF, trsJ, and trsL). The enterococcal part is joined into the pIP501 part by insertion elements IS1216V of E. faecium Tn1545 (three copies), and homologs of IS1062 (E. faecalis) and IS1485 (E. faecium). pRE25 demonstrates that enterococci from fermented food do participate in the molecular communication between Gram-positive and Gram-negative bacteria of the human and animal microflora.

  12. Expression of the MexXY efflux pump in amikacin-resistant isolates of Pseudomonas aeruginosa.

    Science.gov (United States)

    Islam, S; Jalal, S; Wretlind, B

    2004-10-01

    The MexZ-MexX-MexY multidrug efflux system in Pseudomonas aeruginosa was studied to determine its contribution to aminoglycoside resistance. Amikacin-resistant (AR) mutants were generated from P. aeruginosa strain PAO1, and clinical isolates of P. aeruginosa were collected from cystic fibrosis patients. The regulatory gene mexZ and the intergenic region (mexOZ) between mexZ and mexX were investigated for mutation by PCR and DNA sequence analysis. The results showed that 14 of 15 AR clinical isolates and one of ten laboratory mutants had at least one mutation in mexZ and/or mexOZ. To study the effect of mexZ and mexOZ mutations, the production of MexY mRNA was investigated quantitatively by real-time PCR. Seven of ten AR mutants (MIC 4-8 mg/L) produced 8-21-fold more MexY mRNA than PAO1. These isolates were sensitive to fluoroquinolones, carbapenems and ceftazidime. One AR mutant (MIC 64 mg/L) that produced > 200-fold more MexY mRNA than PAO1 was also resistant to fluoroquinolones, carbapenems and ceftazidime. Thirteen of 15 AR clinical isolates produced 3.4-727-fold more MexY mRNA. No evidence was found for the aminoglycoside-modifying enzymes 6'-N-acetyltransferase type Ib, 4'-O-nucleotidyltransferase type IIb or aminoglycoside 3'-phosphotransferase IIps in these strains. Nine AR mutants overproduced MexY without mutations in mexZ or mexOZ, suggesting that MexXY efflux is also regulated by gene(s) other than mexZ.

  13. Antibiotic Resistance of Acinetobacter baumannii in Iran: A Systemic Review of the Published Literature.

    Science.gov (United States)

    Moradi, Jale; Hashemi, Farhad B; Bahador, Abbas

    2015-04-01

    Acinetobacter baumannii is a bacterium responsible for health care-associated infections, and it frequently develops multiple drug resistance (MDR). The prevalence of antibiotic-resistant A. baumannii in Iran has increased, and this may cause significant clinical problems. Therefore, in order to elucidate the development of antibiotic resistance, we performed a systematic review of the literature published on antibiotic-resistant A. baumannii reported in Iran. Thirty-six publications that met the criteria for inclusion were reviewed from an initial 87 papers. Selected papers published between 2008 and September 2014, were categorized on the basis of the sample collecting year been between 2001 and 2013. Analysis of data revealed that, in general, there was an increase in antimicrobial resistance. During the initial time point of these studies (2001-2007) there was a high rate of resistance to all antibiotics, with the exception of carbapenems, lipopeptides, and aminoglycosides that had a low resistance rate in comparison with the others. Also, the resistance rate was increased in one group of these three antimicrobial groups from 2010 to 2013. In particular, there was an increase in resistance to carbapenems (imipenem and meropenem) from 2010-2011 and 2012-2013, whereas no significant change in the resistance rate of the other two antimicrobial groups (lipopeptides and aminoglycosides) during the study time was observed, although we did observe certain trends in amikacin (aminoglycoside group antibiotic) between 2011-2012 and 2012-2013. These findings indicate that antimicrobial resistance of A. baumannii in Iran has increased, which may very well affect the antimicrobial resistance of this organism worldwide. Based on these results, novel prevention and treatment strategies against A. baumannii infections are warranted. Furthermore, these data may assist in revising treatment guidelines and regional policies in care units to slow the emergence of antimicrobial

  14. Functional genomics in Campylobacter coli identified a novel streptomycin resistance gene located in a hypervariable genomic region.

    Science.gov (United States)

    Olkkola, Satu; Culebro, Alejandra; Juntunen, Pekka; Hänninen, Marja-Liisa; Rossi, Mirko

    2016-07-01

    Numerous aminoglycoside resistance genes have been reported in Campylobacter spp. often resembling those from Gram-positive bacterial species and located in transferable genetic elements with other resistance genes. We discovered a new streptomycin (STR) resistance gene in Campylobactercoli showing 27-34 % amino acid identity to aminoglycoside 6-nucleotidyl-transferases described previously in Campylobacter. STR resistance was verified by gene expression and insertional inactivation. This ant-like gene differs from the previously described aminoglycoside resistance genes in Campylobacter spp. in several aspects. It does not appear to originate from Gram-positive bacteria and is located in a region corresponding to a previously described hypervariable region 14 of C. jejuni with no other known resistance genes detected in close proximity. Finally, it does not belong to a multiple drug resistance plasmid or transposon. This novel ant-like gene appears widely spread among C. coli as it is found in strains originating both from Europe and the United States and from several, apparently unrelated, hosts and environmental sources. The closest homologue (60 % amino acid identity) was found in certain C. jejuni and C. coli strains in a similar genomic location, but an association with STR resistance was not detected. Based on the findings presented here, we hypothesize that Campylobacter ant-like gene A has originated from a common ancestral proto-resistance element in Campylobacter spp., possibly encoding a protein with a different function. In conclusion, whole genome sequencing allowed us to fill in a knowledge gap concerning STR resistance in C. coli by revealing a novel STR resistance gene possibly inherent to Campylobacter.

  15. Bactericidal and cytotoxic effect of combination of norfloxacin and 5-fluorouracil.

    Science.gov (United States)

    Castelli, M; Bertolini, A; Baggio, G; Aresca, P; Bossa, R; Galatulas, I

    1989-01-01

    Using the agar dilution technique, we examined the in vitro antibacterial activity of 5-fluorouracil and norfloxacin alone and in association against several bacterial strains. When administered in association, the two drugs did not antagonize each other in tests carried out on strains both sensitive and resistant to penicillins, cephalosporins, aminoglycosides, tetracyclines; furthermore their respective antibacterial properties remained largely unimpaired. The cytotoxic activity and the antitumoral effect of a combination of 5-fluorouracil and norfloxacin was determined in cultured tumor cells, and in mice bearing Ehrlich ascites carcinoma. No significant interference with the cytotoxic activity and antitumoral activity of 5-fluorouracil was observed.

  16. Characterization of Tn6238 with a New Allele of aac(6′)-Ib-cr

    Science.gov (United States)

    Quiroga, María P.; Orman, Betina; Errecalde, Laura; Kaufman, Sara

    2015-01-01

    Here, we report that the genetic structure of Tn1331 remained conserved in Argentina from 1989 to 2013 (72 of 73 isolates), with the exception being the plasmid-borne Tn1331-like transposon Tn6238 containing a new aac(6′)-Ib-cr allele recovered from a colistin-resistant Klebsiella pneumoniae clinical isolate. A bioinformatic analysis of aac(6′)-Ib-like gene cassettes suggests that this new aac(6′)-Ib-cr allele emerged through mutation or homologous recombination in the Tn1331 genetic platform. Tn6238 is a novel platform for the dissemination of aminoglycoside and fluoroquinolone resistance determinants. PMID:25691640

  17. Expression of theaac(6')-Ib-crGene in Class 1 Integrons.

    Science.gov (United States)

    Raherison, Sophie; Jove, Thomas; Gaschet, Margaux; Pinault, Emilie; Tabesse, Aurore; Torres, Carmen; Ploy, Marie-Cécile

    2017-05-01

    aac(6')-Ib-cr is a plasmid-mediated quinolone resistance gene embedded within a gene cassette, most often within an integron. It confers resistance to quinolones and aminoglycosides. We investigated the role of a 101-bp fragment frequently present upstream of the aac(6')-Ib-cr gene cassette and found that it contributes to the expression of aac(6')-Ib-cr and provides an alternative start codon, confirming the length of the AAC(6')-Ib-cr protein to 199 amino acids. Copyright © 2017 American Society for Microbiology.

  18. Radioimmunological determination of gentamycin and tobramycin in surgical intensive medicine

    International Nuclear Information System (INIS)

    Glaubitt, D.; Drechsler, H.J.; Staedtische Krankenanstalten Krefeld

    1979-01-01

    In 119 patients aged 16-86 who, within the framwork of surgical intensive care because of infections dangerous to life, had been treated with the aminoglucoside antibiotics gentamycin or tobramycin and who partly had renal dysfunction, gentamycin or tobramycin in plasma or in serum were determined radioimmunologically, either daily or at intervals of several days. Efforts were made to keep the concentration of the aminoglycoside antibiotic within the therapeutic range. This control of the therapy was particularly useful in short-term changes of the renal function because it facilitates the quick adaptation of the dosage of gentamycin or tobramycin to the assumed requirements. (orig.) [de

  19. 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

    identified in genes encoding components of the respiratory chain. Given the high frequencies of SCVs isolated clinically it is vital to understand the conditions that promote or select for SCVs. RESULTS: In this study we have examined how exposure to sub-inhibitory concentrations of antibiotics...... 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...

  20. Draft genome sequence of a GES-5-producing Serratia marcescens isolated in southern Brazil.

    Science.gov (United States)

    Nodari, Carolina Silva; Siebert, Marina; Matte, Ursula da Silveira; Barth, Afonso Luís

    Serratia marcescens is a Gram-negative rod intrinsically resistant to polymyxins and usually associated with wound, respiratory and urinary tract infections. The whole genome of the first GES-5-producing S. marcescens isolated from a Brazilian patient was sequenced using Ion Torrent PGM System. Besides bla GES-5 , we were able to identify genes encoding for other β-lactamases, for aminoglycoside modifying enzymes and for an efflux pump to tetracyclines. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  1. Occurrence of Diverse Antimicrobial Resistance Determinants in Genetically Unrelated Biocide Tolerant Klebsiella pneumoniae.

    Directory of Open Access Journals (Sweden)

    Amitabha Mondal

    Full Text Available Nosocomial infections due to Klebsiella pneumoniae is a significant problem in health care settings worldwide. In this study, we examined the antimicrobial susceptibility, genetic profiles and mechanisms of antibiotic resistance in K. pneumoniae isolates of Indian origin. To our knowledge this is the first report demonstrating the high prevalence of β-lactamases, aminoglycoside modifying enzymes, quinolone resistance genes besides demonstrating the involvement of active efflux in K. pneumoniae Indian isolates. This study has enabled us to correlate the phenotypic and genotypic characteristics in K. pneumoniae, providing an important base for continued monitoring and epidemiological studies of this emerging nosocomial pathogen in Indian hospitals.

  2. Resistance of potential probiotic lactic acid bacteria and bifidobacteria of African and European origin to antimicrobials: Determination and transferability of the resistance genes to other bacteria

    DEFF Research Database (Denmark)

    Ouoba, Labia Irene Ivette; Lei, Vicki; Jensen, Lars Bogø

    2008-01-01

    Probiotic bacteria and starter cultures of Lactobacillus, Weissella and Bifidobacterium of African and European origins were studied and compared for their susceptibility to antimicrobials. The study included, for all isolates, determination of MICs (Minimal Inhibitory Concentration) for 24...... levels of intrinsic resistance were found among the tested species. Positive amplicons were obtained for resistance genes encoding aminoglycoside (aph(3')-III, aadA, aadE) and tetracycline (tet(S)) from isolates from Europe and macrolide (erm(B)) from an isolate from Africa. However, only the erm(B) gene...

  3. Recurrent Chronic Ambulatory Peritoneal Dialysis-Associated Infection due to Rothia dentocariosa

    Directory of Open Access Journals (Sweden)

    Shaun K Morris

    2004-01-01

    Full Text Available Rothia dentocariosa is a commensal organism of the human oropharynx. Clinical infection due to this organism is rare. A case of recurrent peritoneal dialysis-related peritonitis caused by R dentocariosa and a review of the literature is reported. Isolation of R dentocariosa from dialysate fluid should not be dismissed as a contaminant. Although there are no interpretive criteria for antimicrobial susceptibility testing, R dentocariosa appears to be susceptible to a variety of antibiotics including beta-lactams, vancomycin and aminoglycosides. Optimal therapy of peritoneal dialysis peritonitis caused by this organism may also require removal of the catheter.

  4. Chemopreventive role of Coriandrum sativum against gentamicin-induced renal histopathological damage in rats

    Directory of Open Access Journals (Sweden)

    Lakhera Abhijeet

    2015-06-01

    Full Text Available Drug induced nephrotoxicity is one of the most common causes of renal failure. Gentamicin belongs to aminoglycosides, which elicit nephrotoxic potential. Natural antioxidants from plants demonstrate a number of biotherapeutic activities. Coriander is an important medicinal plant known for its hepatoprotective, diuretic, carminative, digestive and antihelminthic potential. This study was designed to investigate whether the extract of Coriandrum sativum ameliorates the nephrotoxicity induced by gentamicin in rats. Dried coriander powder was coarsely grinded and subjected to defatting by petroleum ether and further with ethyl acetate. The extract was filtered and subjected to phytochemical and phytoanalytical studies.

  5. Prevalence and characteristics of chronic kidney disease among Danish adults with cystic fibrosis

    DEFF Research Database (Denmark)

    Berg, Kristina H; Ryom, Lene; Faurholt-Jepsen, Daniel

    2018-01-01

    BACKGROUND: With improved prognosis of CF, comorbidities including chronic kidney disease (CKD) are becoming increasingly important. Identification of those at highest CKD risk is hence a priority. METHODS: In this cross-sectional study, adults with CF attending the Copenhagen CF Centre...... median duration of chronic pulmonary infection (28.3 (20.0-35.8) vs. 20.0 (9.9-34.7) years; p=0.008) and with longer intravenous aminoglycosides use (606 (IQR, 455-917) vs. 273 (IQR, 91-826) days, p=0.005). CONCLUSIONS: The CKD prevalence is high and related to age, diabetes, chronic infection...

  6. Deciphering the resistome of the widespread P. aeruginosa ST175 international high-risk clone through whole genome sequencing

    DEFF Research Database (Denmark)

    Cabot, Gabriel; López-Causapé, Carla; Ocampo-Sosa, Alain A.

    2016-01-01

    were included for comparison. The typical resistance profile of ST175 included penicillins, cephalosporins, monobactams, carbapenems, aminoglycosides, and fluoroquinolones. In the phylogenetic analysis, the four French isolates clustered together with the two isolates from one of the Spanish regions...... specific ampR mutations leading to ampC overexpression, specific mutations in oprD conferring carbapenem resistance or a mexZ mutation leading to MexXY overexpression. All isolates additionally harbored an aadB gene conferring gentamicin and tobramycin resistance. Several other resistance traits were...

  7. 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

  8. Antibacterianos de acción sistémica: Parte II. Otros grupos de antibióticos

    Directory of Open Access Journals (Sweden)

    Manuel Cué Brugueras

    1998-08-01

    Full Text Available Se presenta la segunda parte de una revisión bibliográfica sobre los antibacterianos de acción sistémica, la cual incluye grupos de antibióticos tan importantes como aminociclitoles, aminoglucósidos, diaminopirimidinas, estreptograminas, fosfomicinas, fusidanos, glicopéptidos, lincosamidas, macrólidos, nitrofuranos, nitroimidazoles, polipéptios, quinolonas y rifamicinasThe second part of the literature review on systemic antibacterial drugs is presented. It deals with such important groups of antibiotics as aminociclitol, aminoglycosides, diaminopirimidine, streptogramin, fosfomycin, fusidane, glycopeptides, lincosamides, macrolides, nitrofurans, nitroimidazols, polypeptides, quinolones, and rifamycins

  9. Phosphoribosyl Diphosphate (PRPP): Biosynthesis, Enzymology, Utilization, and Metabolic Significance

    DEFF Research Database (Denmark)

    Hove-Jensen, Bjarne; Andersen, Kasper R; Kilstrup, Mogens

    2017-01-01

    . PRPP is utilized in the biosynthesis of purine and pyrimidine nucleotides, the amino acids histidine and tryptophan, the cofactors NAD and tetrahydromethanopterin, arabinosyl monophosphodecaprenol, and certain aminoglycoside antibiotics. The participation of PRPP in each of these metabolic pathways...... analysis. PRPP, furthermore, is an effector molecule of purine and pyrimidine nucleotide biosynthesis, either by binding to PurR or PyrR regulatory proteins or as an allosteric activator of carbamoylphosphate synthetase. Genetic analyses have disclosed a number of mutants altered in the PRPP synthase...

  10. Synthesis of heterocycles: Indolo (2,1-a) isoquinolines, renewables, and aptamer ligands for cellular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Beasley, Jonathan [Ames Laboratory (AMES), Ames, IA (United States)

    2013-01-01

    In this thesis, we explore both total syntheses and methodologies of several aromatic heterocyclic molecules. Extensions of the Kraus indole synthesis toward 2-substituted and 2,3-disubstituted indoles, as well as biologically attractive indolo[2,1-a]isoquinolines are described. Recent renewable efforts directed to commodity maleic acid and the first reported furan-based ionic liquids are described. Our total synthesis of mRNA aptamer ligand PDC-Gly, and its dye coupled forms, plus aminoglycoside dye coupled ligands used in molecular imaging, are described.

  11. High prevalence of plasmid-mediated 16S rRNA methylase gene rmtB among Escherichia coli clinical isolates from a Chinese teaching hospital

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    Zhang Xue-qing

    2010-06-01

    Full Text Available Abstract Background Recently, production of 16S rRNA methylases by Gram-negative bacilli has emerged as a novel mechanism for high-level resistance to aminoglycosides by these organisms in a variety of geographic locations. Therefore, the spread of high-level aminoglycoside resistance determinants has become a great concern. Methods Between January 2006 and July 2008, 680 distinct Escherichia coli clinical isolates were collected from a teaching hospital in Wenzhou, China. PCR and DNA sequencing were used to identify 16S rRNA methylase and extended-spectrum β-lactamase (ESBL genes, including armA and rmtB, and in situ hybridization was performed to determine the location of 16S rRNA methylase genes. Conjugation experiments were subsequently performed to determine whether aminoglycoside resistance was transferable from the E. coli isolates via 16S rRNA methylase-bearing plasmids. Homology of the isolates harboring 16S rRNA methylase genes was determined using pulse-field gel electrophoresis (PFGE. Results Among the 680 E. coli isolates, 357 (52.5%, 346 (50.9% and 44 (6.5% isolates were resistant to gentamicin, tobramycin and amikacin, respectively. Thirty-seven of 44 amikacin-resistant isolates harbored 16S rRNA methylase genes, with 36 of 37 harboring the rmtB gene and only one harboring armA. The positive rates of 16S rRNA methylase genes among all isolates and amikacin-resistant isolates were 5.4% (37/680 and 84.1% (37/44, respectively. Thirty-one isolates harboring 16S rRNA methylase genes also produced ESBLs. In addition, high-level aminoglycoside resistance could be transferred by conjugation from four rmtB-positive donors. The plasmids of incompatibility groups IncF, IncK and IncN were detected in 34, 3 and 3 isolates, respectively. Upstream regions of the armA gene contained ISCR1 and tnpU, the latter a putative transposase gene,. Another putative transposase gene, tnpD, was located within a region downstream of armA. Moreover, a

  12. [Tsukamurella infections. Review of the literature apropos of a case].

    Science.gov (United States)

    Rey, D; Fraisse, P; Riegel, P; Piemont, Y; Lang, J M

    1997-01-01

    The genus Tsukamurella belongs to the family Nocardiaceae, and is an environmental saprophyte. The type species is Tsukamurella paurometabola. Its microbiological identification and differentiation from the other species containing mycolic acids can be difficult. There has been a few cases of human infections reported, usually in patients with special conditions, such as chronic lung pathology, immuno-suppression (leukemia, solid tumors, maybe HIV-infection) or the long-term use of indwelling catheters. The treatment of choice, despite the lack of adequate guidelines, is an antibiotherapy combining a beta-lactam and an aminoglycoside; catheter removal appears to be essential for cure.

  13. 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.

  14. Benzoxazinone kanamycin A conjugate. A new fluorescent probe suitable to detect mycoplasmas in cell culture.

    Science.gov (United States)

    Monsigny, M; Midoux, P; Depierreux, C; Bebear, C; Le Bris, M T; Valeur, B

    1990-01-01

    The synthesis of a new benzoxazinone derivative suitable to detect early infection of cultured cells with mycoplasmas is described. p-[beta-(7-dimethylamino 1,4-benzoxazin 2-one 3yl)-vinyl]- phenylpropenoic acid was coupled to kanamycin A, an aminoglycoside leading to a cationic fluorescent probe which fluoresces at 600 nm upon excitation at 490 nm. This fluorescent probe is shown to heavily label the glycocallix of all the mycoplasma strains tested which are found to be associated with contaminated cultured cells and to allow an easy and rapid detection of contamination by fluorescence microscopy and flow cytometry.

  15. Cross-resistance of Mycobacterium tuberculosis isolates among streptomycin, kanamycin and amikacin.

    Science.gov (United States)

    Sugawara, I; Zhang, J; Li, C

    2009-06-01

    Seventy-four streptomycin (SM)-resistant M. tuberculosis clinical isolates were subjected to cross-resistance drug testing against two major aminoglycosides, kanamycin (KM) and amikacin (AMK). Among them, 15 clinical isolates (20.3%) were resistant to both KM and AMK. Fifteen (80%) of 19 KM-resistant isolates were AMK-resistant. Fifteen SM, KM, and AMK resistant isolates harbored rrs mutation, but only two had rrs and rpsL double mutations. Low-level SM resistance was associated with rpsL mutation, whereas high-level SM resistance was linked to rrs mutation.

  16. Two Novel Antibiotic Resistance Genes, tet(44) and ant(6)-Ib, Are Located within a Transferable Pathogenicity Island in Campylobacter fetus subsp. fetus▿

    Science.gov (United States)

    Abril, Carlos; Brodard, Isabelle; Perreten, Vincent

    2010-01-01

    New tetracycline and streptomycin resistance genes, tet(44) and ant(6)-Ib, were identified in Campylobacter fetus subsp. fetus within a transferable pathogenicity island that is typically unique to Campylobacter fetus subsp. venerealis. The 640-amino-acid tetracycline resistance determinant, Tet 44, belongs to a class of proteins that confers resistance to tetracycline and minocycline by ribosomal protection. The 286-amino-acid streptomycin resistance determinant, ANT(6)-Ib, belongs to a family of aminoglycoside nucleotidyltransferases. The resistance phenotypes were demonstrated by gene inactivation and expression. PMID:20479200

  17. 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.

  18. Antibacterial, modulatory activity of antibiotics and toxicity from Rhinella jimi (Stevaux, 2002) (Anura: Bufonidae) glandular secretions.

    Science.gov (United States)

    Sales, Débora Lima; Morais-Braga, Maria Flaviana Bezerra; Santos, Antonia Thassya Lucas Dos; Machado, Antonio Judson Targino; Araujo Filho, João Antonio de; Dias, Diógenes de Queiroz; Cunha, Francisco Assis Bezerra da; Saraiva, Rogério de Aquino; Menezes, Irwin Rose Alencar de; Coutinho, Henrique Douglas Melo; Costa, José Galberto Martins; Ferreira, Felipe Silva; Alves, Rômulo Romeu da Nóbrega; Almeida, Waltécio de Oliveira

    2017-08-01

    The increase in microorganisms with resistance to medications has caused a strong preoccupation within the medical and scientific community. Animal toxins studies, such as parotoid glandular secretions from amphibians, possesses a great potential in the development of drugs, such as antimicrobials, as these possess bioactive compounds. It was evaluated Rhinella jimi (Stevaux, 2002) glandular secretions against standard and multi-resistant bacterial strains; the effect of secretions combined with drugs; and determined the toxicity using two biologic in vivo models, and a in vitro model with mice livers. Standard strains were used for the determination of the Minimum Inhibitory Concentration (MIC), while for the modulatory activity of antibiotics, the clinical isolates Escherichia coli 06, Pseudomonas aeruginosa 03 and Staphylococcus aureus 10 were used. Modulatory activity was evaluated by the broth microdilution method with aminoglycosides and β-lactams as target antibiotics. The secretions in association with the antibiotics have a significant reduction in MIC, both the aminoglycosides and β-lactams. The toxicity and cytotoxicity results were lower than the values used in the modulation. R. jimi glandular secretions demonstrated clinically relevant results regarding the modulation of the tested antimicrobials. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  19. Protective effects of nettle (Urtica dioica extract against acute kidney injury induced by gentamycin in the rat

    Directory of Open Access Journals (Sweden)

    سید پژمان مرتضوی

    2017-11-01

    Full Text Available Aminoglycosides are often used in combination with beta-lactam antibiotics and have a rapid bactericidal effect, are available at an affordable cost and have less incidence of resistance, making them a drug of choice for treatment of several life-threatening infections. However, the nephrotoxic effects of aminoglycosides prevent their long term use. The use of herbal extracts in order to decrease injuries of injurious materials has long been considered. The present study was conducted in order to investigate the protective effects of nettle (Urtica dioica extract against gentamicin induced kidney injuries in the rat. Forty five male Wistar rats were divided into 9 groups consisting of: 1-healthy control group, 2- negative control group that received tween 20 (extract solvent, 3- patient control group which received onlygentamicin at 100 mg/kg, experimental healthy groups 4-6 which received nettle extract at 50, 100 and 200 mg/kg and patient experimental groups 7-9 which received nettle extract along with gentamicin at 100 mg/kg. At the end of the experiment (28 days, blood samples were obtained, and the kidneys were removed for histopathologic investigations. The results showed that gentamicin alone induced renal tissue damage and significantly increased the serum levels of creatinine and urea (p

  20. Novel, Synergistic Antifungal Combinations that Target Translation Fidelity

    Science.gov (United States)

    Moreno-Martinez, Elena; Vallieres, Cindy; Holland, Sara L.; Avery, Simon V.

    2015-01-01

    There is an unmet need for new antifungal or fungicide treatments, as resistance to existing treatments grows. Combination treatments help to combat resistance. Here we develop a novel, effective target for combination antifungal therapy. Different aminoglycoside antibiotics combined with different sulphate-transport inhibitors produced strong, synergistic growth-inhibition of several fungi. Combinations decreased the respective MICs by ≥8-fold. Synergy was suppressed in yeast mutants resistant to effects of sulphate-mimetics (like chromate or molybdate) on sulphate transport. By different mechanisms, aminoglycosides and inhibition of sulphate transport cause errors in mRNA translation. The mistranslation rate was stimulated up to 10-fold when the agents were used in combination, consistent with this being the mode of synergistic action. A range of undesirable fungi were susceptible to synergistic inhibition by the combinations, including the human pathogens Candida albicans, C. glabrata and Cryptococcus neoformans, the food spoilage organism Zygosaccharomyces bailii and the phytopathogens Rhizoctonia solani and Zymoseptoria tritici. There was some specificity as certain fungi were unaffected. There was no synergy against bacterial or mammalian cells. The results indicate that translation fidelity is a promising new target for combinatorial treatment of undesirable fungi, the combinations requiring substantially decreased doses of active components compared to each agent alone. PMID:26573415

  1. Time course of apoptotic cell death in guinea pig cochlea following intratympanic gentamicin application.

    Science.gov (United States)

    Suzuki, Mitsuya; Ushio, Munetaka; Yamasoba, Tatsuya

    2008-07-01

    The present study showed that the molecular signal that promotes the death of cochlear hair cells (HCs) induced by intratympanic gentamicin application is significant before the manifestation of morphological and functional changes. The effect of agents that protect the HCs from aminoglycoside ototoxicity is influenced by the timing of their administration. However, morphological, functional and molecular changes in the cochlea in the early stage following aminoglycoside application have rarely been studied. Therefore, we examined the chronological changes in the cochlea following intratympanic gentamicin application. Small pieces of gelatin sponge soaked with gentamicin (40 mg/ml) were placed on the round window membrane of mature guinea pigs, and the tympanic bulla was filled with gentamicin solution. They were euthanized at 6, 12, 18, 24, and 48 h following gentamicin application. Auditory brainstem responses (ABRs) were measured before gentamicin application and immediately before euthanasia, and the extent of missing and TUNEL-positive HCs was evaluated. ABR thresholds significantly increased 18 h or later following gentamicin application, and the loss of HCs was seen at 24 and 48 h. While functional and morphological changes were not evident until 18 h after gentamicin application, substantial amounts of TUNEL-positive HCs appeared at 12 h.

  2. Functional metagenomic characterization of antibiotic resistance genes in agricultural soils from China.

    Science.gov (United States)

    Su, Jian Qiang; Wei, Bei; Xu, Chun Yan; Qiao, Min; Zhu, Yong Guan

    2014-04-01

    Soil has been regarded as a rich source of antibiotic resistance genes (ARGs) due to the complex microbial community and diverse antibiotic-producing microbes in soil, however, little is known about the ARGs in unculturable bacteria. To investigate the diversity and distribution of ARGs in soil and assess the impact of agricultural practice on the ARGs, we screened soil metagenomic library constructed using DNA from four different agricultural soil for ARGs. We identified 45 clones conferring resistance to minocycline, tetracycline, streptomycin, gentamicin, kanamycin, amikacin, chloramphenicol and rifampicin. The similarity of identified ARGs with the closest protein in GenBank ranged from 26% to 92%, with more than 60% of identified ARGs had low similarity less than 60% at amino acid level. The identified ARGs include aminoglycoside acetyltransferase, aminoglycoside 6-adenyltransferase, ADP-ribosyl transferase, ribosome protection protein, transporters and other antibiotic resistant determinants. The identified ARGs from the soil with manure application account for approximately 70% of the total ARGs in this study, implying that manure amendment may increase the diversity of antibiotic resistance genes in soil bacteria. These results suggest that antibiotic resistance in soil remains unexplored and functional metagenomic approach is powerful in discovering novel ARGs and resistant mechanisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. 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.

  4. Two Cases of Multi-antibiotic Resistant Cronobacter spp. Infections of Infants in China.

    Science.gov (United States)

    Cui, Jing Hua; Yu, Bo; Xiang, Yun; Zhang, Zhen; Zhang, Ting; Zeng, Ying Chun; Cui, Zhi Gang; Huo, Xi Xiang

    2017-08-01

    Infections by Cronobacter spp. are hazardous to infants since they can lead to neonatal meningitis, bacteremia, and necrotizing enterocolitis. Cronobacter spp. are frequently resistant to β-lactam derivatives, macrolides, and aminoglycosides. In addition, multi-resistant strains have also been detected. In China, the isolation rate of Cronobacter spp. from commercial powdered infant formula (PIF) or follow-up formula (FUF) is relatively high. Nevertheless, clinical cases of Cronobacter infection have been ignored to date. Here we describe two cases of Cronobacter infection detected at the Wuhan Women and Children Medical Care Center Hospital (Wuhan City, China). We provide the genomic analysis of the isolates and the antibiotic-resistance profiles of the two strains. The Cronobacter strains identified in this study were not susceptible to third-generation cephalosporins, aminoglycoside, and/or trimethoprim-sulfamethoxazole. Whole genome sequencing revealed various genes known to encode antibiotic resistance. Future studies are needed to determine whether the genes predicted in this study are functional. As with Enterobacter spp., the antibiotic resistance of Cronobacter is a serious issue that requires more attention. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  5. Crystallization and preliminary crystallographic analysis of hygromycin B phosphotransferase from Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Iino, Daisuke [Department of Bioscience, Tokyo University of Agriculture, Tokyo 156-8502 (Japan); Takakura, Yasuaki [Division of Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572 (Japan); Kuroiwa, Mika; Kawakami, Ryouta; Sasaki, Yasuyuki [Department of Bioscience, Tokyo University of Agriculture, Tokyo 156-8502 (Japan); Hoshino, Takayuki [Division of Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572 (Japan); Ohsawa, Kanju [Department of Bioscience, Tokyo University of Agriculture, Tokyo 156-8502 (Japan); Nakamura, Akira [Division of Integrative Environmental Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572 (Japan); Yajima, Shunsuke, E-mail: yshun@nodai.ac.jp [Department of Bioscience, Tokyo University of Agriculture, Tokyo 156-8502 (Japan)

    2007-08-01

    The crystallization and preliminary X-ray studies of the aminoglycoside antibiotic-modifying enzyme hygromycin B phosphotransferase from E. coli are reported. Aminoglycoside antibiotics, such as hygromycin, kanamycin, neomycin, spectinomycin and streptomycin, inhibit protein synthesis by acting on bacterial and eukaryotic ribosomes. Hygromycin B phosphotransferase (Hph; EC 2.7.1.119) converts hygromycin B to 7′′-O-phosphohygromycin using a phosphate moiety from ATP, resulting in the loss of its cell-killing activity. The Hph protein has been crystallized for the first time using a thermostable mutant and the hanging-drop vapour-diffusion method. The crystal provided diffraction data to a resolution of 2.1 Å and belongs to space group P3{sub 2}21, with unit-cell parameters a = b = 71.0, c = 125.0 Å. Crystals of complexes of Hph with hygromycin B and AMP-PNP or ADP have also been obtained in the same crystal form as that of the apoprotein.

  6. Noninvasive Test for Mitochondrial DNA A1555G Mutation Associated with Deafness.

    Science.gov (United States)

    Fan, Wenlu; Zhu, Yi; Tang, Xiaowen; Xue, Ling

    2017-01-01

    The homoplasmic mitochondrial DNA (mtDNA) A1555G mutation in the highly conserved decoding site of 12S rRNA has been associated with aminoglycoside-induced and nonsyndromic hearing loss in many families worldwide. The A1555G mutation detection is an important part of hearing screening. At present, blood samples are the most common source of genomic DNA. However, drawing blood is invasive for individuals. The whole genomic DNA of samples carrying mitochondrial DNA A1555G mutation (LX010 and LX044) with aminoglycoside-induced and nonsyndromic deafness as well as wild type were used as templates. The PCR products were analyzed by DNA sequencing, PCR-RFLP, dot blot, and southern blot. The DNA sequencing, PCR-RFLP, dot blot, and southern blot demonstrate that buccal cell DNA can be used for the screening and identification of the A1555G mutation as well as peripheral blood DNA. This study established a convenient, noninvasive and suitable for clinical determination of mtDNA A1555G mutation associated with deafness.

  7. Pseudomonas aeruginosa May Accumulate Drug Resistance Mechanisms without Losing Its Ability To Cause Bloodstream Infections▿

    Science.gov (United States)

    Hocquet, Didier; Berthelot, Philippe; Roussel-Delvallez, Micheline; Favre, Roger; Jeannot, Katy; Bajolet, Odile; Marty, Nicole; Grattard, Florence; Mariani-Kurkdjian, Patricia; Bingen, Edouard; Husson, Marie-Odile; Couetdic, Gérard; Plésiat, Patrick

    2007-01-01

    In this study, we systematically investigated the resistance mechanisms to β-lactams, aminoglycosides, and fluoroquinolones of 120 bacteremic strains of Pseudomonas aeruginosa. Pulsed-field gel electrophoresis genotyping showed that 97 of these strains were represented by a single isolate, 10 by 2 and 1 by 3 clonally related isolates, respectively. Seventy-five percent (90 out of 120) of the bacteremic P. aeruginosa strains displayed a significant resistance to one or more of the tested antimicrobials (up to 11 for 1 strain). These strains were found to harbor a great diversity of resistance mechanisms (up to 7 in 1 strain), leading to various levels of drug resistance. Interestingly, 11 and 36% of the isolates appeared to overproduce the MexAB-OprM and MexXY-OprM efflux systems, respectively. Altogether, our results show that P. aeruginosa may accumulate intrinsic (overproduction of cephalosporinase AmpC, increased drug efflux, fluoroquinolone target mutations, and deficient production of porin OprD) and exogenous (production of secondary β-lactamases and aminoglycoside-modifying enzymes) resistance mechanisms without losing its ability to generate severe bloodstream infections. Consequently, clinicians should be aware that multidrug-resistant P. aeruginosa may remain fully pathogenic. PMID:17682106

  8. Pseudomonas Aeruginosa: Resistance to the Max

    Science.gov (United States)

    Poole, Keith

    2011-01-01

    Pseudomonas aeruginosa is intrinsically resistant to a variety of antimicrobials and can develop resistance during anti-pseudomonal chemotherapy both of which compromise treatment of infections caused by this organism. Resistance to multiple classes of antimicrobials (multidrug resistance) in particular is increasingly common in P. aeruginosa, with a number of reports of pan-resistant isolates treatable with a single agent, colistin. Acquired resistance in this organism is multifactorial and attributable to chromosomal mutations and the acquisition of resistance genes via horizontal gene transfer. Mutational changes impacting resistance include upregulation of multidrug efflux systems to promote antimicrobial expulsion, derepression of ampC, AmpC alterations that expand the enzyme's substrate specificity (i.e., extended-spectrum AmpC), alterations to outer membrane permeability to limit antimicrobial entry and alterations to antimicrobial targets. Acquired mechanisms contributing to resistance in P. aeruginosa include β-lactamases, notably the extended-spectrum β-lactamases and the carbapenemases that hydrolyze most β-lactams, aminoglycoside-modifying enzymes, and 16S rRNA methylases that provide high-level pan-aminoglycoside resistance. The organism's propensity to grow in vivo as antimicrobial-tolerant biofilms and the occurrence of hypermutator strains that yield antimicrobial resistant mutants at higher frequency also compromise anti-pseudomonal chemotherapy. With limited therapeutic options and increasing resistance will the untreatable P. aeruginosa infection soon be upon us? PMID:21747788

  9. Adverse drug reaction and toxicity caused by commonly used antimicrobials in canine practice

    Directory of Open Access Journals (Sweden)

    K. Arunvikram

    2014-05-01

    Full Text Available An adverse drug reaction (ADR is a serious concern for practicing veterinarians and other health professionals, and refers to an unintended, undesired and unexpected response to a drug that negatively affects the patient's health. It may be iatrogenic or genetically induced, and may result in death of the affected animal. The ADRs are often complicated and unexpected due to myriad clinical symptoms and multiple mechanisms of drug-host interaction. Toxicity due to commonly used drugs is not uncommon when they are used injudiciously or for a prolonged period. Licosamides, exclusively prescribed against anaerobic pyoderma, often ends with diarrhoea and vomiting in canines. Treatment with Penicillin and β-lactam antibiotics induces onset of pemphigious vulgare, drug allergy or hypersensitivity. Chloroamphenicol and aminoglycosides causes Gray's baby syndrome and ototoxicity in puppies, respectively. Aminoglycosides are very often associated with nephrotoxicity, ototoxicity and neuromuscular blockage. Injudicious use of fluroquinones induces the onset of arthropathy in pups at the weight bearing joints. The most effective therapeutic measure in managing ADR is to treat the causative mediators, followed by supportive and symptomatic treatment. So, in this prospective review, we attempt to bring forth the commonly occurring adverse drug reactions, their classification, underlying mechanism, epidemiology, treatment and management as gleaned from the literature available till date and the different clinical cases observed by the authors.

  10. A Higher Prevalence Rate of Campylobacter in Retail Beef Livers Compared to Other Beef and Pork Meat Cuts

    Science.gov (United States)

    Noormohamed, Aneesa; Fakhr, Mohamed K.

    2013-01-01

    The objectives of this study were to determine the prevalence of Campylobacter jejuni and Campylobacter coli in retail beef, beef livers, and pork meats purchased from the Tulsa (OK, USA) area and to further characterize the isolates obtained through antimicrobial susceptibility testing. A total of 97 chilled retail beef (50 beef livers and 47 other cuts), and 100 pork samples were collected. The prevalence of Campylobacter in beef livers was 39/50 (78%), while no Campylobacter was isolated from the other beef cuts. The prevalence in pork samples was 2/100 (2%). A total of 108 Campylobacter isolates (102 beef livers isolates and six pork isolates) were subjected to antimicrobial resistance profiling against sixteen different antimicrobials that belong to eight different antibiotic classes. Of the six pork Campylobacter coli isolates, four showed resistance to all antimicrobials tested. Among the beef liver isolates, the highest antibiotic resistances were to tetracyclines and β-lactams, while the lowest resistances were to macrolides, aminoglycosides, lincosamides, and phenicols. Resistances to the fluoroquinolone, macrolide, aminoglycoside, tetracycline, β-lactam, lincosamide, and phenicol antibiotic classes were significantly higher in Campylobacter coli than Campylobacter jejuni isolates. Multidrug Resistance (MDR) among the 102 Campylobacter (33 Campylobacter jejuni and 69 Campylobacter coli) beef liver isolates was significantly higher in Campylobacter coli (62%) than Campylobacter jejuni (39%). The high prevalence of Campylobacter in retail beef livers and their antimicrobial resistance raise concern about the safety of these retail products. PMID:23698698

  11. Identification and characterization of a novel aac(6')-Iag associated with the blaIMP-1-integron in a multidrug-resistant Pseudomonas aeruginosa.

    Science.gov (United States)

    Kobayashi, Kanao; Hayashi, Ikue; Kouda, Syuntaro; Kato, Fuminori; Fujiwara, Tamaki; Kayama, Shizuo; Hirakawa, Hideki; Itaha, Hideyuki; Ohge, Hiroki; Gotoh, Naomasa; Usui, Tsuguru; Matsubara, Akio; Sugai, Motoyuki

    2013-01-01

    In a continuing study from Dec 2006 to Apr 2008, we characterized nine multi-drug resistant Pseudomonas aeruginosa strains isolated from four patients in a ward at the Hiroshima University Hospital, Japan. Pulsed-field gel electrophoresis of SpeI-digested genomic DNAs from the isolates suggested the clonal expansion of a single strain; however, only one strain, NK0009, was found to produce metallo-β-lactamase. PCR and subsequent sequencing analysis indicated NK0009 possessed a novel class 1 integron, designated as In124, that carries an array of four gene cassettes: a novel aminoglycoside (AG) resistance gene, aac(6')-Iag, blaIMP-1, a truncated form of blaIMP-1, and a truncated form of aac(6')-Iag. The aac(6')-Iag encoded a 167-amino-acid protein that shows 40% identity with AAC(6')-Iz. Recombinant AAC(6')-Iag protein showed aminoglycoside 6'-N-acetyltransferase activity using thin-layer chromatography (TLC) and MS spectrometric analysis. Escherichia coli carrying aac(6')-Iag showed resistance to amikacin, arbekacin, dibekacin, isepamicin, kanamycin, sisomicin, and tobramycin; but not to gentamicin. A conjugation experiment and subsequent Southern hybridization with the gene probes for blaIMP-1 and aac(6')-Ig strongly suggested In124 is on a conjugal plasmid. Transconjugants acquired resistance to gentamicin and were resistant to virtually all AGs, suggesting that the In124 conjugal plasmid also possesses a gene conferring resistance to gentamicin.

  12. [Occurrence and characterisation of aac(6')-Ib-cr gene encoding fluoroquinolone-modifying enzyme in clinical ciprofloxacin-resistant Enterobacteriaceae strains isolated in Poland].

    Science.gov (United States)

    Piekarska, Katarzyna; Rzeczkowska, Magdalena; Chróst, Anna; Wołkowicz, Tomasz; Zacharczuk, Katarzyna; Bareja, Elzbieta; Olak, Monika; Gierczyński, Rafał

    2013-01-01

    The aac(6')-Ib-cr gene encodes a variant of aminoglycoside acetyltransferase that confers reduced susceptibility to hydrophilic fluoroquinolones such as ciprofloxacin and norfloxacin. AAC(6')-Ib-cr has two amino acid changes, Trp 102Arg and Asp179Tyr, which together are necessery and sufficient for the enzyme's ability to reduce the activity of fluoroquinolones, including ciprofloxacin and norfloxacin. The aim of this study was to evaluate the prevelance of aac(6')-Ib-cr determinant among 15 Enterobacteriaceae isolates randomly chosen from 215 fluorochinolone resistant strains recovered during the 6 months of 2010. The aac(6')-Ib was detected by PCR. The presence of aac(6')-Ib-cr gene variant was futher identified by digestion with BseGI (BtsCI) and sequencing. 11/15 of the resistant (MIC CIP 2-1024 microg/ml) Enterobacteriaceae strains carried aac(6')-Ib-cr variant. This is the first study identifying the variant of aminoglycoside acetyltransferase determinant in Poland. Our results demonstrate that this enzym may be even more widespread than Qnr determinants among fluoroquinolone resistant Enterobacteriaceae in Poland.

  13. 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.

  14. Differential effects of paromomycin on ribosomes of Leishmania mexicana and mammalian cells.

    Science.gov (United States)

    Fernández, Marisa M; Malchiodi, Emilio L; Algranati, Israel D

    2011-01-01

    Paromomycin, an aminoglycoside antibiotic having low mammalian cell toxicity, is one of the drugs currently used in the chemotherapy of cutaneous and visceral leishmaniasis. In order to understand the mode of action of this antibiotic at the molecular level, we have investigated the effects of paromomycin on protein synthesis in Leishmania and its mammalian hosts. We were able to demonstrate that in vivo protein synthesis in the promastigote stage of the parasite and its proliferation rate are markedly inhibited by paromomycin while being only slightly affected by other aminoglycoside antibiotics, such as streptomycin and neomycin B. Furthermore, both in vitro polypeptide synthesis induced by poly(U) as mRNA and accuracy of translation are significantly decreased by paromomycin in cell-free systems containing ribosomal particles of Leishmania promastigotes. Conversely, when ribosomes from mammalian cells are used instead of the protozoan particles, polyphenylalanine synthesis is only barely reduced by the antibiotic and the translation misreading remains almost unaltered. Surface plasmon resonance analysis of the interaction between paromomycin and protozoan or mammalian cell ribosomal RNAs shows a strong binding of antibiotic to the parasite ribosomal decoding site and practically no interaction with the mammalian cell counterpart. Our results indicating differential effects of paromomycin on the translation processes of the Leishmania parasite and its mammalian hosts can explain the therapeutic efficiency of this antibiotic as an antileishmaniasis agent.

  15. Mutant mtDNA at 1555 A to G in 12S rRNA gene and hypersusceptibility of mitochondrial translation to streptomycin can be co-transferred to rho 0 HeLa cells.

    Science.gov (United States)

    Inoue, K; Takai, D; Soejima, A; Isobe, K; Yamasoba, T; Oka, Y; Goto, Y; Hayashi, J

    1996-06-25

    Human skin fibroblast line 95-119, which had been isolated from the mother of a Japanese patient with aminoglycoside-induced deafness and a 1555 A to G mutation at 12S rRNA gene in mitochondrial DNA (mtDNA), was used to investigate the relationship between the 1555 mtDNA mutation and its pathogenicity. By the intercellular transfer of mtDNA with or without the 1555 mutation to mtDNA-less (rho 0) HeLa cells, we isolated cybrid clones and found that the mitochondrial translation in a cybrid clone repopulated with the homoplasmic 1555 mutation showed the highest susceptibility to streptomycin. These observations suggest that the genotype of the mutant mtDNA and the phenotype of hypersusceptibility to streptomycin observed in 95-119 fibroblasts were co-transferred simultaneously to rho 0 HeLa cells, supporting the idea that the homoplasmic 1555 mtDNA mutation is involved in the pathogenesis leading to aminoglycoside-induced hearing loss.

  16. Association between the introduction of a new cystic fibrosis inhaled antibiotic class and change in prevalence of patients receiving multiple inhaled antibiotic classes.

    Science.gov (United States)

    Dasenbrook, Elliott C; Konstan, Michael W; VanDevanter, Donald R

    2015-05-01

    In 2010, aztreonam for inhalation solution joined aminoglycosides and colistimethate as a new cystic fibrosis (CF) chronic inhaled antimicrobial therapy. We studied how the introduction of this new inhaled antibiotic class changed the management of US CF patients. The use of inhaled aminoglycosides, colistimethate, and aztreonam among patients followed in the CF Foundation Patient Registry was analyzed by age group, lung disease stage, and microbiologic status both annually, and at individual visits between 2009 and 2012. The overall prevalence of inhaled antibiotic use did not change during the period, but the prevalence of annual and any visit treatment with >1 inhaled antibiotic class more than doubled. Adults, those with advanced lung disease, and those with >1 Pseudomonas aeruginosa respiratory culture were more likely to receive >1 antibiotic class. Inhaled antibiotic management of US CF patients has dramatically changed in association with the introduction of a third inhaled antibiotic class. Copyright © 2014 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  17. Previous Antibiotic Exposure and Antimicrobial Resistance Patterns of Acinetobacter spp. and Pseudomonas aeruginosa Isolated from Patients with Nosocomial Infections

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    Zorana M. Djordjevic

    2017-12-01

    Full Text Available Background: The alarming spread of antibiotic-resistant bacteria causing healthcare-associated infections has been extensively reported in recent medical literature. Aims: To compare trends in antimicrobial consumption and development of resistance among isolates of Acinetobacter spp. and Pseudomonas aeruginosa that cause hospital infections. Study Design: Cross-sectional study. Methods: A study was conducted in a tertiary healthcare institution in central Serbia, during the 7-year period between January 2009 and December 2015. The incidence rate of infections caused by Acinetobacter or Pseudomonas, as well as their resistance density to commonly used antibiotics, were calculated. Utilization of antibiotics was expressed as the number of defined daily doses per 1000 patient-days. Results: A statistically significant increase in resistance density in 2015 compared to the first year of observation was noted for Acinetobacter, but not for Pseudomonas, to third-generation cephalosporins (p=0.008, aminoglycosides (p=0.005, carbapenems (p=0.003, piperacillin/tazobactam (p=0.025, ampicillin/sulbactam (p=0.009 and tigecycline (p=0.048. Conclusion: Our study showed that there is an association between the resistance density of Acinetobacter spp. and utilization of carbapenems, tigecycline and aminoglycosides. A multifaceted intervention is needed to decrease the incidence rate of Acinetobacter and Pseudomonas hospital infections, as well as their resistance density to available antibiotics

  18. [Therapeutics strategies for the management of urinary tract infection in children].

    Science.gov (United States)

    Launay, E; Bingen, E; Cohen, R

    2012-11-01

    Urinary tract infections is one of the most common bacterial infections in pediatrics The increasing involvement of multiresistant bacteria including E. coli producing extended spectrum ß-lactamase (ESBL) makes its management difficult. The purpose of this article is to evaluate the state of the art and to propose ways of thinking about the management of E. coli urinary tract infection in children. The current percentage (less than 10%) of E. coli strains resistant to third generation cephalosporins and the relative efficiency of the latter, should not led to an immediate change of our protocols. Nevertheless, we should verify as soon as possible susceptibility of E. coli responsible for urinary tract infections and consider other therapeutic options for initial therapy and adaptation after obtaining antibiogram. The use of an aminoglycosid as initial treatment seems very interesting. Aminoglycosides have a very good distribution in the renal parenchyma and are still working on the majority of ESBL-producing bacteria. A rapid oral relay after 48 to 72 hours may be proposed according to the results of the susceptibility with either cotrimoxazole, cefixime, ciprofloxacin or an association cefixime-amoxicilline/clavulanate. The treatment of cystitis due to ESBL E. coli is much less problematic given the good urinary beta-lactam antibiotics diffusion. If clinical improvement occurs, even if antibiogram shows that the strain is resistant to the antibiotic prescribed, it is usually unnecessary to change treatment. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  19. Infections in acute leukemia in Indian Children

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    B Roy

    2014-01-01

    Full Text Available Aims: In the present study acute leukemic children were studied to determine the incidence and principal site of infection, correlation with absolute neutrophil count, causative organisms and to standardize the initial empirical anti microbial therapy. Materials and methods: A total 40 children in the age group 6 month to 12 year with acute leukemia relapse were included in this study. A total 82 infectious episodes including 61 febrile episodes were investigated for infectious etiology. Results: We found that the frequency of infections increased significantly with the degree of immunocompromisation specially neutropenia (ANC < 500/cmm. The skin and soft tissue was the commonest site of infection (26.83%, followed by respiratory tract (21.95%. Staphylococcus nonhemolytic coagulase-negative (34%, followed by Klebsiella (17% were the most common organisms isolated from blood. Staphylococcus non-hemolytic coagulase-negative was also the commonest isolate (26% from other sites of infection. Most strains were sensitive to Cloxacillin, cephalosporin and aminoglycosides. Conclusion: For the treatment of febrile episodes, empirical use of beta-lactamase resistant penicillin e.g. Cloxacillin or cephalosporin combined with an aminoglycosides with a broad spectrum antifungal like fluconazole in selective cases at the first sign of infection is recommended. Journal of College of Medical Sciences-Nepal, 2013, Vol-9, No-1, 40-47 DOI: http://dx.doi.org/10.3126/jcmsn.v9i1.9672

  20. Functional characterization of bacteria isolated from ancient arctic soil exposes diverse resistance mechanisms to modern antibiotics.

    Directory of Open Access Journals (Sweden)

    Gabriel G Perron

    Full Text Available 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.

  1. 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.

  2. Regional up-regulation of NOX2 contributes to the differential vulnerability of outer hair cells to neomycin.

    Science.gov (United States)

    Qi, Meihao; Qiu, Yang; Zhou, Xueying; Tian, Keyong; Zhou, Ke; Sun, Fei; Yue, Bo; Chen, Fuquan; Zha, Dingjun; Qiu, Jianhua

    2018-03-20

    In hearing loss induced by aminoglycoside antibiotics, the outer hair cells (OHCs) in the basal turn are always more susceptible than OHCs in the apical turn, while the underlying mechanisms remain unknown. In this study, we reported that NAPDH oxidase 2 (NOX2) played an important role in the OHCs damage preferentially in the basal turn. Normally, NOX2 was evenly expressed in OHCs among different turns, at a relatively low level. However, after neomycin treatment, NOX2 was dominantly induced in OHCs in the basal turn. In vivo and in vitro studies demonstrated that inhibition of NOX2 significantly alleviated neomycin-induced OHCs damages, as seen from both the cleaved caspase-3 and TUNEL staining. Moreover, gp91 ds-tat delivery and DHE staining results showed that NOX2-derived ROS was responsible for neomycin ototoxicity. Taken together, our study shows that regional up-expression of NOX2 and subsequent increase of ROS in OHCs of the basal turn is an important factor contributing to the vulnerability of OHCs there, which should shed light on the prevention of hearing loss induced by aminoglycoside antibiotics. Copyright © 2018. Published by Elsevier Inc.

  3. Class 1 Integron-Borne, Multiple-Antibiotic Resistance Encoded by a 150-Kilobase Conjugative Plasmid in Epidemic Vibrio cholerae O1 Strains Isolated in Guinea-Bissau

    Science.gov (United States)

    Dalsgaard, Anders; Forslund, Anita; Petersen, Andreas; Brown, Derek J.; Dias, Francisco; Monteiro, Serifo; Mølbak, Kåre; Aaby, Peter; Rodrigues, Amabelia; Sandström, Anita

    2000-01-01

    In the 1996–1997 cholera epidemic in Guinea-Bissau, surveillance for antimicrobial resistance showed the emergence of a multidrug-resistant strain of Vibrio cholerae O1 during the course of the epidemic. The strain was resistant to ampicillin, erythromycin, tetracycline, furazolidone, aminoglycosides, trimethoprim, and sulfamethoxazole. Concomitant with the emergence of this strain, we observed a resurgence in the number of registered cholera cases as well as an increase in the case fatality rate from 1.0% before the emergence of the multiple-drug-resistant strain to 5.3% after the emergence of the strain. Our study shows that the strain contained a 150-kb conjugative multiple-antibiotic resistance plasmid with class 1 integron-borne gene cassettes encoding resistance to trimethoprim (dhfrXII) and aminoglycosides [ant(3")-1a]). The finding of transferable resistance to almost all of the antibiotics commonly used to treat cholera is of great public health concern. Studies should be carried out to determine to what extent the strain or its resistance genes have been spread to other areas where cholera is endemic. PMID:11015401

  4. Feasibility of nonsense mutation readthrough as a novel therapeutical approach in propionic acidemia.

    Science.gov (United States)

    Sánchez-Alcudia, Rocío; Pérez, Belén; Ugarte, Magdalena; Desviat, Lourdes R

    2012-06-01

    Aminoglycosides and other compounds can promote premature termination codon (PTC) readthrough constituting a potential therapy for patients with nonsense mutations. In a cohort of 190 propionic acidemia (PA) patients, we have identified 12 different nonsense mutations, six of them novel, accounting for 10% of the mutant alleles. Using an in vitro system, we establish the proof-of-principle that nonsense mutations in the PCCA and PCCB genes encoding both subunits of the propionyl-CoA carboxylase (PCC) enzyme can be partially suppressed by aminoglycosides, with different efficiencies depending on the sequence context. To correct the metabolic defect, the amino acid incorporated at the PTC should support protein function, and this has been evaluated in silico and by in vitro expression analysis of the predicted missense changes, most of which retain partial activity, confirming the feasibility of the approach. In patients' fibroblasts cultured with readthrough drugs, we observe a fourfold to 50-fold increase in the PCC activity, reaching up to 10-15% level of treated control cells. The ability to partially correct nonsense PCCA and PCCB alleles represents a potential therapy or supplementary treatment for a number of propionic acidemia (PA) patients, encouraging further clinical trials with readthrough drugs without toxic effects such as PTC124 or other newly developed compounds. Hum Mutat 33:973-980, 2012. © 2012 Wiley Periodicals, Inc. © 2012 Wiley Periodicals, Inc.

  5. Geldanamycin induces production of heat shock protein 70 and partially attenuates ototoxicity caused by gentamicin in the organ of Corti explants

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    Haupt Heidemarie

    2009-09-01

    Full Text Available Abstract Background Heat shock protein 70 (HSP70 protects inner ear cells from damage and death induced by e.g. heat or toxins. Benzoquinone ansamycin antibiotic geldanamycin (GA was demonstrated to induce the expression of HSP70 in various animal cell types. The aim of our study was to investigate whether GA induces HSP70 in the organ of Corti (OC, which contains the auditory sensory cells, and whether GA can protect these cells from toxicity caused by a common aminoglycoside antibiotic gentamicin. Methods To address these questions, we used the OC explants isolated from p3-p5 rats. As a read-out, we used RT-PCR, ELISA and immunofluorescence. Results We found that GA at the concentration of 2 μM efficiently induced HSP70 expression on mRNA and protein level in the OC explants. Confocal microscopy revealed that HSP70 induced by GA is expressed by hair cells and interdental cells of spiral limbus. Preincubation of explants with 2 μM GA prior to adding gentamicin (500 μM significantly reduced the loss of outer but not inner hair cells, suggesting different mechanisms of otoprotection needed for these two cell types. Conclusion GA induced HSP70 in the auditory sensory cells and partially protected them from toxicity of gentamicin. Understanding the molecular mechanisms of GA otoprotection may provide insights for preventative therapy of the hearing loss caused by aminoglycoside antibiotics.

  6. Prevalence and bacterial susceptibility of hospital acquired urinary tract infection

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    Dias Neto José Anastácio

    2003-01-01

    Full Text Available PURPOSE: Urinary tract infection is the most common nosocomially acquired infection. It is important to know the etiology and antibiotic susceptibility infectious agents to guide the initial empirical treatment. OBJECTIVE: To determine the prevalence of bacterial strains and their antibiotic susceptibility in nosocomially acquired urinary tract infection in a university hospital between January and June 2003. METHODS: We analyzed the data of 188 patients with positive urine culture (= 10(5 colony-forming units/mL following a period of 48 hours after admission. RESULTS: Half of patients were male. Mean age was 50.26 ± 22.7 (SD, range 3 months to 88 years. Gram-negative bacteria were the agent in approximately 80% of cases. The most common pathogens were E. coli (26%, Klebsiella sp. (15%, P. aeruginosa (15% and Enterococcus sp. (11%. The overall bacteria susceptibility showed that the pathogens were more sensible to imipenem (83%, second or third generation cephalosporin and aminoglycosides; and were highly resistant to ampicillin (27% and cefalothin (30%. It is important to note the low susceptibility to ciprofloxacin (42% and norfloxacin (43%. CONCLUSION: This study suggests that if one can not wait the results of urine culture, the best choices to begin empiric treatment are imipenem, second or third generation cephalosporin and aminoglycosides. Cefalothin and ampicillin are quite ineffective to treat these infections.

  7. Selective atonal gene delivery improves balance function in a mouse model of vestibular disease.

    Science.gov (United States)

    Schlecker, C; Praetorius, M; Brough, D E; Presler, R G; Hsu, C; Plinkert, P K; Staecker, H

    2011-09-01

    Loss of balance is often due to loss of vestibular hair cells. In mammals, regeneration of functional hair cells in the mature sensory epithelium is limited; therefore, loss of sensory cells can lead to debilitating balance problems. Delivery of the transcription factor atonal (atoh1) after aminoglycoside ototoxicity has previously been shown to induce the transdifferentiation of supporting cells into new hair cells and restore function. A problem with mouse aminoglycoside models is that the partial loss of hair cells seen in human disease is difficult to establish consistently. To more closely mirror human clinical balance dysfunction, we have used systemic application of 3,3'-iminodipropionitrile (IDPN), a vestibulotoxic nitrile compound known to cause vestibular hair cell loss, to induce a consistent partial loss of vestibular hair cells. To determine if balance function could be restored, we delivered atoh1 using a new adenovirus vector, based on Ad28. The Ad28 adenovector is based on a human serotype with a low seroprevalence that appears to target gene delivery to vestibular supporting cells. To further provide cell type selectivity of gene delivery, we expressed atoh1 using the supporting cell-specific glial fibrillary acid protein promoter. Delivery of this vector to IDPN-damaged vestibular organs resulted in a significant recovery of vestibular hair cells and restoration of balance, as measured by time on rotarod compared with untreated controls.

  8. Practices related to late-onset sepsis in very low-birth weight preterm infants

    Directory of Open Access Journals (Sweden)

    Maria Regina Bentlin

    2015-04-01

    Full Text Available OBJECTIVE: To understand the practices related to late-onset sepsis (LOS in the centers of the Brazilian Neonatal Research Network, and to propose strategies to reduce the incidence of LOS. METHODS: This was a cross-sectional descriptive multicenter study approved by the Ethics Committee. Three questionnaires regarding hand hygiene, vascular catheters, and diagnosis/treatment of LOS were sent to the coordinator of each center. The center with the lowest incidence of LOS was compared with the others. RESULTS: All 16 centers answered the questionnaires. Regarding hand hygiene, 87% use chlorhexidine or 70% alcohol; alcohol gel is used in 100%; 80% use bedside dispensers (50% had one dispenser for every two beds; practical training occurs in 100% and theoretical training in 70% of the centers, and 37% train once a year. Catheters: 94% have a protocol, and 75% have a line insertion team. Diagnosis/treatment: complete blood count and blood culture are used in 100%, PCR in 87%, hematological scores in 75%; oxacillin and aminoglycosides is the empirical therapy in 50% of centers. Characteristics of the center with lowest incidence of LOS: stricter hand hygiene; catheter insertion and maintenance groups; use of blood culture, PCR, and hematological score for diagnosis; empirical therapy with oxacillin and aminoglycoside. CONCLUSION: The knowledge of the practices of each center allowed for the identification of aspects to be improved as a strategy to reduce LOS, including: alcohol gel use, hand hygiene training, implementation of catheter teams, and wise use of antibiotic therapy.

  9. 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

  10. Carbapenemases in Klebsiella pneumoniae and Other Enterobacteriaceae: an Evolving Crisis of Global Dimensions

    Science.gov (United States)

    Tzouvelekis, L. S.; Markogiannakis, A.; Psichogiou, M.; Tassios, P. T.

    2012-01-01

    Summary: The spread of Enterobacteriaceae, primarily Klebsiella pneumoniae, producing KPC, VIM, IMP, and NDM carbapenemases, is causing an unprecedented public health crisis. Carbapenemase-producing enterobacteria (CPE) infect mainly hospitalized patients but also have been spreading in long-term care facilities. Given their multidrug resistance, therapeutic options are limited and, as discussed here, should be reevaluated and optimized. Based on susceptibility data, colistin and tigecycline are commonly used to treat CPE infections. Nevertheless, a review of the literature revealed high failure rates in cases of monotherapy with these drugs, whilst monotherapy with either a carbapenem or an aminoglycoside appeared to be more effective. Combination therapies not including carbapenems were comparable to aminoglycoside and carbapenem monotherapies. Higher success rates have been achieved with carbapenem-containing combinations. Pharmacodynamic simulations and experimental infections indicate that modification of the current patterns of carbapenem use against CPE warrants further attention. Epidemiological data, though fragmentary in many countries, indicate CPE foci and transmission routes, to some extent, whilst also underlining the lack of international collaborative systems that could react promptly and effectively. Fortunately, there are sound studies showing successful containment of CPE by bundles of measures, among which the most important are active surveillance cultures, separation of carriers, and assignment of dedicated nursing staff. PMID:23034326

  11. Metagenomic Analysis of Apple Orchard Soil Reveals Antibiotic Resistance Genes Encoding Predicted Bifunctional Proteins▿

    Science.gov (United States)

    Donato, Justin J.; Moe, Luke A.; Converse, Brandon J.; Smart, Keith D.; Berklein, Flora C.; McManus, Patricia S.; Handelsman, Jo

    2010-01-01

    To gain insight into the diversity and origins of antibiotic resistance genes, we identified resistance genes in the soil in an apple orchard using functional metagenomics, which involves inserting large fragments of foreign DNA into Escherichia coli and assaying the resulting clones for expressed functions. Among 13 antibiotic-resistant clones, we found two genes that encode bifunctional proteins. One predicted bifunctional protein confers resistance to ceftazidime and contains a natural fusion between a predicted transcriptional regulator and a β-lactamase. Sequence analysis of the entire metagenomic clone encoding the predicted bifunctional β-lactamase revealed a gene potentially involved in chloramphenicol resistance as well as a predicted transposase. A second clone that encodes a predicted bifunctional protein confers resistance to kanamycin and contains an aminoglycoside acetyltransferase domain fused to a second acetyltransferase domain that, based on nucleotide sequence, was predicted not to be involved in antibiotic resistance. This is the first report of a transcriptional regulator fused to a β-lactamase and of an aminoglycoside acetyltransferase fused to an acetyltransferase not involved in antibiotic resistance. PMID:20453147

  12. Evaluating the resistance pattern of gram-negative bacteria during three years at the nephrology ward of a referral hospital in southwest of Iran.

    Science.gov (United States)

    Karimzadeh, Iman; Sadeghimanesh, Niloofar; Mirzaee, Mona; Sagheb, Mohammad Mahdi

    2017-07-01

    Gram-negative bacteria are associated with an increase in rates of antibacterial resistance. In most low- and middle-income countries such as Iran, there is no continuous surveillance system for antibiotic resistance. The purpose of this survey was to determine the pattern of antimicrobial sensitivity of gram-negative bacteria within 3 consecutive years at a nephrology ward of Nemazee hospital in Shiraz. During a 3-year period from 2013 to 2015 at the adult nephrology ward, bacteriological data of all biological samples of hospitalized patients in favor of gram-negative microorganisms were analyzed retrospectively. Antimicrobial susceptibility was performed by the Kirby-Bauer disc diffusion method. The most common gram negative bacterium isolated from biological samples was Escherichia coli (43.9%). The highest (86.3%-94.1%) antibacterial resistance rate was associated with Acinetobacter spp. The most frequent resistance was seen with cephalosporins. In contrast to ceftriaxone, ciprofloxacin, and trimethoprim/sulfamethoxazole, nitrofurantoin and aminoglycosides remained their acceptable activity against E. coli. At least three-fourths (75%) of Acinetobacter spp. isolates was resistant to either aminoglycosides or imipenem. All (100%) isolated Acinetobacter spp. and Pseudomonas aeruginosa species were susceptible to colistin. The rate of Acinetobacter spp. and P. aeruginosa resistant to three or more drugs was 81.7% and 74.6%, respectively. The resistant rate of gram negative pathogens to different tested antibacterial agents was considerably high and has increased during the recent three years in our center.

  13. Production of β-globin and adult hemoglobin following G418 treatment of erythroid precursor cells from homozygous β039 thalassemia patients

    Science.gov (United States)

    Salvatori, Francesca; Breveglieri, Giulia; Zuccato, Cristina; Finotti, Alessia; Bianchi, Nicoletta; Borgatti, Monica; Feriotto, Giordana; Destro, Federica; Canella, Alessandro; Brognara, Eleonora; Lampronti, Ilaria; Breda, Laura; Rivella, Stefano; Gambari, Roberto

    2013-01-01

    In several types of thalassemia (including β039-thalassemia), stop codon mutations lead to premature translation termination and to mRNA destabilization through nonsense-mediated decay. Drugs (for instance aminoglycosides) can be designed to suppress premature termination, inducing a ribosomal readthrough. These findings have introduced new hopes for the development of a pharmacologic approach to the cure of this disease. However, the effects of aminoglycosides on globin mRNA carrying β-thalassemia stop mutations have not yet been investigated. In this study, we have used a lentiviral construct containing the β039- thalassemia globin gene under control of the β-globin promoter and a LCR cassette. We demonstrated by fluorescence-activated cell sorting (FACS) analysis the production of β-globin by K562 cell clones expressing the β039-thalassemia globin gene and treated with G418. More importantly, after FACS and high-performance liquid chromatography (HPLC) analyses, erythroid precursor cells from β039-thalassemia patients were demonstrated to be able to produce β-globin and adult hemoglobin after treatment with G418. This study strongly suggests that ribosomal readthrough should be considered a strategy for developing experimental strategies for the treatment of β0-thalassemia caused by stop codon mutations. PMID:19810011

  14. Monitoring antibiotic resistance in ocular microorganisms: results from the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) 2009 surveillance study.

    Science.gov (United States)

    Haas, Wolfgang; Pillar, Chris M; Torres, Mohana; Morris, Timothy W; Sahm, Daniel F

    2011-10-01

    To determine the antibacterial susceptibility profile of bacterial pathogens from ocular infections against relevant aminoglycoside, β-lactam, cephalosporin, chloramphenicol, fluoroquinolone, glycopeptide, lincosamide, and macrolide antibacterial agents. Laboratory investigation. Isolates from patients with bacterial eye infections were collected prospectively by 34 institutions across the United States and were submitted to a central laboratory for inclusion in the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) study. Minimum inhibitory concentrations were determined by microbroth dilution for 200 Staphylococcus aureus (S. aureus), 144 coagulase-negative staphylococci, 75 Streptococcus pneumoniae (S. pneumoniae), 73 Haemophilus influenzae (H. influenzae), and 100 Pseudomonas aeruginosa (P. aeruginosa) isolates. A large proportion of S. aureus and coagulase-negative staphylococci isolates were resistant to oxacillin/methicillin, azithromycin, or fluoroquinolones; 46.5% of S. aureus, 58.3% of coagulase-negative staphylococci, 9.0% of P. aeruginosa, and 9.3% of pneumococcal isolates were nonsusceptible to 2 or more antibacterial drug classes. Only 2.7% of H. influenzae isolates were nonsusceptible to 1 of the agents tested. Methicillin-resistant staphylococci were statistically more likely (all P < .0038) also to be resistant to fluoroquinolones, aminoglycosides, and macrolides. Resistance to 1 or more antibiotics is prevalent among ocular bacterial pathogens. Current resistance trends should be considered before initiating empiric treatment of common eye infections. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Drug-induced acid-base disorders.

    Science.gov (United States)

    Kitterer, Daniel; Schwab, Matthias; Alscher, M Dominik; Braun, Niko; Latus, Joerg

    2015-09-01

    The incidence of acid-base disorders (ABDs) is high, especially in hospitalized patients. ABDs are often indicators for severe systemic disorders. In everyday clinical practice, analysis of ABDs must be performed in a standardized manner. Highly sensitive diagnostic tools to distinguish the various ABDs include the anion gap and the serum osmolar gap. Drug-induced ABDs can be classified into five different categories in terms of their pathophysiology: (1) metabolic acidosis caused by acid overload, which may occur through accumulation of acids by endogenous (e.g., lactic acidosis by biguanides, propofol-related syndrome) or exogenous (e.g., glycol-dependant drugs, such as diazepam or salicylates) mechanisms or by decreased renal acid excretion (e.g., distal renal tubular acidosis by amphotericin B, nonsteroidal anti-inflammatory drugs, vitamin D); (2) base loss: proximal renal tubular acidosis by drugs (e.g., ifosfamide, aminoglycosides, carbonic anhydrase inhibitors, antiretrovirals, oxaliplatin or cisplatin) in the context of Fanconi syndrome; (3) alkalosis resulting from acid and/or chloride loss by renal (e.g., diuretics, penicillins, aminoglycosides) or extrarenal (e.g., laxative drugs) mechanisms; (4) exogenous bicarbonate loads: milk-alkali syndrome, overshoot alkalosis after bicarbonate therapy or citrate administration; and (5) respiratory acidosis or alkalosis resulting from drug-induced depression of the respiratory center or neuromuscular impairment (e.g., anesthetics, sedatives) or hyperventilation (e.g., salicylates, epinephrine, nicotine).

  16. Carbapenemases: Partners in crime.

    Science.gov (United States)

    Bush, Karen

    2013-03-01

    Carbapenemases, β-lactamases that inactivate carbapenems and most β-lactam antibiotics, are most widely known for their ability to confer resistance to β-lactams. They include serine carbapenemases, such as the widespread KPC family of enzymes, and the metallo-β-lactamases that contain the IMP, NDM and VIM enzyme families acquired by Gram-negative bacteria on transferable elements. These enzymes are almost always produced by organisms that encode at least one other β-lactamase, with as many as eight different β-lactamase genes detected in a single isolate. This consortium of β-lactamases includes a full spectrum of molecular and biochemical characteristics, providing the producing organism with a range of catalytic activities. In addition to the variety of β-lactamases found in carbapenemase-producing Gram-negative pathogens are multiple other resistance factors, especially aminoglycoside-modifying enzymes and 16S rRNA methylases that confer resistance to aminoglycosides. Other acquired genes encode fluoroquinolone, trimethoprim, sulfonamide, rifampicin and chloramphenicol resistance determinants on mobile elements that travel together with β-lactamase genes. Thus, the recent proliferation of transferable carbapenemases serves to magnify resistance to virtually all antibiotic classes. Judicial use of current antibiotics and a quest for novel antibacterial agents are necessary, as multidrug-resistant bacteria continue to multiply. Copyright © 2013 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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.

  19. Efflux-mediated fluoroquinolone resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7: identification of a novel MexS variant involved in upregulation of the mexEF-oprN multidrug efflux operon.

    Science.gov (United States)

    Morita, Yuji; Tomida, Junko; Kawamura, Yoshiaki

    2015-01-01

    The emergence of multidrug-resistant Pseudomonas aeruginosa has become a serious problem in medical settings. P. aeruginosa clinical isolate PA7 is resistant to fluoroquinolones, aminoglycosides, and most β-lactams but not imipenem. In this study, enhanced efflux-mediated fluoroquinolone resistance of PA7 was shown to reflect increased expression of two resistance nodulation cell division (RND) -type multidrug efflux operons, mexEF-oprN and mexXY-oprA. Such a clinical isolate has rarely been reported because MexEF-OprN-overproducing mutants often increase susceptibility to aminoglycosides apparently owing to impairment of the MexXY system. A mutant of PA7 lacking three RND-type multidrug efflux operons (mexAB-oprM, mexEF-oprN, and mexXY-oprA) was susceptible to all anti-pseudomonas agents we tested, supporting an idea that these RND-type multidrug efflux transporters are molecular targets to overcome multidrug resistance in P. aeruginosa. mexEF-oprN-upregulation in P. aeruginosa PA7 was shown due to a MexS variant harboring the Valine-155 amino acid residue. This is the first genetic evidence shown that a MexS variant causes mexEF-oprN-upregulation in P. aeruginosa clinical isolates.

  20. Efflux-mediated fluoroquinolone resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7: identification of a novel MexS variant involved in upregulation of the mexEF-oprN multidrug efflux operon

    Directory of Open Access Journals (Sweden)

    Yuji eMorita

    2015-01-01

    Full Text Available The emergence of multidrug-resistant Pseudomonas aeruginosa has become a serious problem in medical settings. P. aeruginosa clinical isolate PA7 is resistant to fluoroquinolones, aminoglycosides, and most -lactams but not imipenem. In this study, enhanced efflux-mediated fluoroquinolone resistance of PA7 was shown to reflect increased expression of two resistance nodulation cell division (RND -type multidrug efflux operons, mexEF-oprN and mexXY-oprA. Such a clinical isolate has rarely been reported because MexEF-OprN-overproducing mutants often increase susceptibility to aminoglycosides apparently owing to impairment of the MexXY system. A mutant of PA7 lacking three RND-type multidrug efflux operons (mexAB-oprM, mexEF-oprN, and mexXY-oprA was susceptible to all anti-pseudomonas agents we tested, supporting an idea that these RND-type multidrug efflux transporters are molecular targets to overcome multidrug resistance in P. aeruginosa. mexEF-oprN-upregulation in P. aeruginosa PA7 was shown due to a MexS variant harboring the Valine-155 amino acid residue. This is the first genetic evidence shown that a MexS variant causes mexEF-oprN-upregulation in P. aeruginosa clinical isolates.

  1. Crystallization and preliminary crystallographic analysis of hygromycin B phosphotransferase from Escherichia coli

    International Nuclear Information System (INIS)

    Iino, Daisuke; Takakura, Yasuaki; Kuroiwa, Mika; Kawakami, Ryouta; Sasaki, Yasuyuki; Hoshino, Takayuki; Ohsawa, Kanju; Nakamura, Akira; Yajima, Shunsuke

    2007-01-01

    The crystallization and preliminary X-ray studies of the aminoglycoside antibiotic-modifying enzyme hygromycin B phosphotransferase from E. coli are reported. Aminoglycoside antibiotics, such as hygromycin, kanamycin, neomycin, spectinomycin and streptomycin, inhibit protein synthesis by acting on bacterial and eukaryotic ribosomes. Hygromycin B phosphotransferase (Hph; EC 2.7.1.119) converts hygromycin B to 7′′-O-phosphohygromycin using a phosphate moiety from ATP, resulting in the loss of its cell-killing activity. The Hph protein has been crystallized for the first time using a thermostable mutant and the hanging-drop vapour-diffusion method. The crystal provided diffraction data to a resolution of 2.1 Å and belongs to space group P3 2 21, with unit-cell parameters a = b = 71.0, c = 125.0 Å. Crystals of complexes of Hph with hygromycin B and AMP-PNP or ADP have also been obtained in the same crystal form as that of the apoprotein

  2. Garlic-supplemented diet attenuates gentamicin-induced ototoxicity: an experimental study.

    Science.gov (United States)

    Uzun, Lokman; Balbaloglu, Evrim; Akinci, Harun

    2012-02-01

    Gentamicin sulfate is a potent aminoglycoside antibiotic associated with serious side effects, including ototoxicity. Garlic, with its intrinsic antioxidant activity, may prove beneficial in prevention of ototoxicity. In this study, we investigated the effect of a 4% garlic-supplemented diet on the ototoxicity induced by gentamicin in rats by using brain stem evoked response audiometry. Eighteen male Wistar rats with an intact Preyer's reflex and an initial weight of 220 to 260 g were randomly assigned to a group with gentamicin injection and garlic supplementation, a group with gentamicin injection without garlic supplementation, or a control group (6 rats each group). Gentamicin was given by intraperitoneal injection at 120 mg/kg body weight once daily for 16 days. The garlic-supplemented diet was prepared by adding pulverized whole garlic cloves to standard chow in a 4% proportion. After 21 days, hearing thresholds were evaluated by use of brain stem evoked response audiometry at 10 kHz. The mean (+/- SD) amplitudes of the auditory thresholds (sensation level) measured by use of brain stem evoked response audiometry for the group with garlic supplementation, the group without garlic, and the control group were 43.3 +/- 8.16, 78.0 +/- 4.47, and 16.7 +/- 5.16 dB sensation level, respectively. The differences were statistically significant (p garlic-supplemented diet seems to attenuate aminoglycoside-induced hearing loss.

  3. From CLSI to EUCAST guidelines in the interpretation of antimicrobial susceptibility: What is the effect in our setting?

    Science.gov (United States)

    Sánchez-Bautista, Antonia; Coy, Javier; García-Shimizu, Patricia; Rodríguez, Juan Carlos

    2018-04-01

    Implementation of the breakpoints established in the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines in comparison with those of the Clinical and Laboratory Standards Institute (CLSI) means that the criteria for interpreting the susceptibility of some antimicrobials have been modified, resulting in changes in the reports of accumulated antibiotic susceptibility. The effect of applying EUCAST breakpoints in 10,359 clinical isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus spp. was analysed. By applying EUCAST breakpoints, most antimicrobial susceptibility percentages did not change or changed very slightly. However, a decrease in aminoglycoside susceptibility was observed in Gram-negative bacilli, mainly for amikacin and Pseudomonas aeruginosa (23.2%), although only 5.7% were completely resistant; a notably decrease in the percentage of isolates susceptible to aztreonam was also observed. There was also a marked increase in the number of Staphylococcus aureus strains resistant to clindamycin (51.5%) and aminoglycosides (gentamicin 43.1%). Switching from CLSI to EUCAST criteria in some pathogens alters the percentages of resistance to several antimicrobials, and therefore the local epidemiology of the resistance. These changes should be implemented by a multidisciplinary group in order to analyse the influence of the new data on the empirical treatment protocols of each centre. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  4. Combination Therapy of Sophoraflavanone B against MRSA: In Vitro Synergy Testing

    Directory of Open Access Journals (Sweden)

    Su-Hyun Mun

    2013-01-01

    Full Text Available Sophoraflavanone B (SPF-B, a known prenylated flavonoid, was isolated from the roots of Desmodium caudatum. The aim of this study was to determine the antimicrobial synergism of SPF-B combined with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA. MRSA, a multidrug-resistant pathogen, causes both hospital- and community-acquired infections worldwide. The antimicrobial activity of SPF-B was assessed by the broth microdilution method, checkerboard dilution test, and time-kill curve assay. The MIC of SPF-B for 7 strains of S. aureus ranges from 15.6 to 31.25 μg/mL determined. In the checkerboard method, the combinations of SPF-B with antibiotics had a synergistic effect; SPF-B markedly reduced the MICs of the β-lactam antibiotics: ampicillin (AMP and oxacillin (OXI; aminoglycosides gentamicin (GET; quinolones ciprofloxacin (CIP and norfloxacin (NOR against MRSA. The time-kill curves assay showed that a combined SPF-B and selected antibiotics treatment reduced the bacterial counts below the lowest detectable limit after 24 h. These data suggest that the antibacterial activity of SPF-B against MRSA can be effectively increased through its combination with three groups of antibiotics (β-lactams, aminoglycosides, and quinolones. Our research can be a valuable and significant source for the development of a new antibacterial drug with low MRSA resistance.

  5. Molecular Mechanisms of Intrinsic Streptomycin Resistance in Mycobacterium abscessus.

    Science.gov (United States)

    Dal Molin, Michael; Gut, Myriam; Rominski, Anna; Haldimann, Klara; Becker, Katja; Sander, Peter

    2018-01-01

    Streptomycin, the first drug used for the treatment of tuberculosis, shows limited activity against the highly resistant pathogen Mycobacterium abscessus We recently identified two aminoglycoside-acetylating genes [ aac(2') and eis2 ] which, however, do not affect susceptibility to streptomycin. This suggests the existence of a discrete mechanism of streptomycin resistance. M. abscessus BLASTP analysis identified MAB_2385 as a close homologue of the 3″- O -phosphotransferase [APH(3″)] from the opportunistic pathogen Mycobacterium fortuitum as a putative streptomycin resistance determinant. Heterologous expression of MAB_2385 in Mycobacterium smegmatis increased the streptomycin MIC, while the gene deletion mutant M. abscessus ΔMAB_2385 showed increased streptomycin susceptibility. The MICs of other aminoglycosides were not altered in M. abscessus ΔMAB_2385. This demonstrates that MAB_2385 encodes a specific and prime innate streptomycin resistance determinant in M. abscessus We further explored the feasibility of applying rpsL -based streptomycin counterselection to generate gene deletion mutants in M. abscessus Spontaneous streptomycin-resistant mutants of M. abscessus ΔMAB_2385 were selected, and we demonstrated that the wild-type rpsL is dominant over the mutated rpsL K43R in merodiploid strains. In a proof of concept study, we exploited this phenotype for construction of a targeted deletion mutant, thereby establishing an rpsL -based counterselection method in M. abscessus . Copyright © 2017 American Society for Microbiology.

  6. Versatile nourseothricin and streptomycin/spectinomycin resistance gene cassettes and their use in chromosome integration vectors.

    Science.gov (United States)

    Lehman, Stephanie S; Mladinich, Katherine M; Boonyakanog, Angkana; Mima, Takehiko; Karkhoff-Schweizer, RoxAnn R; Schweizer, Herbert P

    2016-10-01

    An obstacle for the development of genetic systems for many bacteria is the limited number of antibiotic selection markers, especially for bacteria that are intrinsically antibiotic resistant or where utilization of such markers is strictly regulated. Here we describe the development of versatile cassettes containing nourseothricin, streptomycin/spectinomycin, and spectinomycin selection markers. The antibiotic resistance genes contained on these cassettes are flanked by loxP sites with allow their in vivo excision from the chromosome of target bacteria using Cre recombinase. The respective selection marker cassettes were used to derive mini-Tn7 elements that can be used for single-copy insertion of genes into bacterial chromosomes. The utility of the selection markers was tested by insertion of the resulting mini-Tn7 elements into the genomes of Burkholderia thailandensis and B. pseudomallei efflux pump mutants susceptible to aminoglycosides, aminocyclitols, and streptothricins, followed by Cre-mediated antibiotic resistance marker excision. The versatile nourseothricin, streptomycin/spectinomycin and spectinomycin resistance loxP cassette vectors described here extend the repertoire of antibiotic selection markers for genetic manipulation of diverse bacteria that are susceptible to aminoglycosides and aminocyclitols. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Urgent Need to Antibiotic Pharmacokinetic Services for Iranian Health Care Centers

    Directory of Open Access Journals (Sweden)

    Alireza Hayatshahi

    2013-02-01

    Full Text Available Considering the emergence of both Gram negative and Gram positive resistant bacterial strains in the recent years, makes it more prominent to utilize the existed antibiotics in an appropriate and justified way in the treatment of drug resistant infections. Many of the agents currently used to treat bacterial, viral and fungal infections do not need to be pharmacokinetically monitored; it means we do not require their serum levels in order to adjust the dose in a routine manner. Examples of these antibiotics are penicillins, cephalosporins, macrolides, tetracyclines, fluoroquinolones, etc. Of course these agents need dose adjustment based on renal and hepatic functions. On the other hand there are antibiotics which need to be monitored through their serum levels because of three main following reasons: 1-      To avoid overdosing patient and reduce the incidence of toxicities. 2-      To avoid underdosing patient, this may lead to the emergence of resistant strains and treatment failure. 3-      To optimize the dose of antibiotic to achieve the bactericidal or bacteriostatic effects needed to suppress the infective agent. At this point, we are using vancomycin as a broad spectrum Gram positive agent and aminoglycosides both for the synergism for Gram positive coverage and also for treatment of Gram negative infection in combination with other agents. According to the guidelines published by the accredited organizations like Infectious Diseases Society of America (IDSA and American Society of Healthcare Pharmacists (ASHP, it is crucially important to perform therapeutic drug monitoring (TDM for both vancomycin and aminoglycosides based on their serum levels for all patients on these agents. In the other word, it is a wrong antibiotic therapy without monitoring the levels. Almost in all medical centers nationwide including teaching hospitals the clinicians prescribe vancomycin very often and aminoglycosides like gentamicin and

  8. Acute kidney injury in neonatal intensive care: Medicines involved.

    Science.gov (United States)

    Safina, A I; Daminova, M A; Abdullina, G A

    2015-01-01

    The incidence of acute kidney injury (AKI) in neonates in the intensive care units and neonatal intensive care (NICU) according Plotz et al. ranges from 8% to 22% [3]. According to Andreoli, neonatal death due to AKI in NICU amounts up to 10-61% [1]. It should be in the reasons of AKI emphasize.The role of certain drugs, which are widely used in modern neonatology: nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics (aminoglycosides, glycopeptides, carbapenems, 3rd generation cephalosporins), furosemide, enalapril, in contributing to AKI should be emphasized [2]. To identify risk factors for acute kidney injury in neonates in intensive care units and intensive care. We performed a prospective observational case-control study of full-term newborns who were treated in the intensive care unit and neonatal intensive care of the "Children's city hospital №1" Kazan and NICU №3 "Children's Republican Clinical Hospital" in 2011-2014 years.The study included 86 term infants in critical condition, who were hospitalized to the NICU on the first days of life, - the main group. The main criterion of AKI in neonates according to neonatal AKIN classification (2011) is a serum creatinine concentration ≥1.5 mg/dL. We subdivided the main group into two subgroups:subgroup I, AKI+ consisted of 12 term infants in critical condition with the serum creatinine level ≥ 1,5 mg/dL at the age of not younger than 48 hours after birth, which was 14% of all full-term newborns who were at the NICU;subgroup II, AKI- consisted of 74 term infants in critical condition with the serum creatinine level arithmetic means (M) with, standard deviation (σ) and standard error of the mean (m) according to standard formulas. All children were admitted to primary and emergency care with subsequent transfer to the NICU at 1-2 days of life and further treatment in the department of pathology of newborns (DPN). The duration of hospitalization of infants at the NICU for the main group averaged 5,9

  9. Hierarchical Cluster Analysis of Semicircular Canal and Otolith Deficits in Bilateral Vestibulopathy

    Directory of Open Access Journals (Sweden)

    Alexander A. Tarnutzer

    2018-04-01

    Full Text Available BackgroundGait imbalance and oscillopsia are frequent complaints of bilateral vestibular loss (BLV. Video-head-impulse testing (vHIT of all six semicircular canals (SCCs has demonstrated varying involvement of the different canals. Sparing of anterior-canal function has been linked to aminoglycoside-related vestibulopathy and Menière’s disease. We hypothesized that utricular and saccular impairment [assessed by vestibular-evoked myogenic potentials (VEMPs] may be disease-specific also, possibly facilitating the differential diagnosis.MethodsWe searched our vHIT database (n = 3,271 for patients with bilaterally impaired SCC function who also received ocular VEMPs (oVEMPs and cervical VEMPs (cVEMPs and identified 101 patients. oVEMP/cVEMP latencies above the 95th percentile and peak-to-peak amplitudes below the 5th percentile of normal were considered abnormal. Frequency of impairment of vestibular end organs (horizontal/anterior/posterior SCC, utriculus/sacculus was analyzed with hierarchical cluster analysis and correlated with the underlying etiology.ResultsRates of utricular and saccular loss of function were similar (87.1 vs. 78.2%, p = 0.136, Fisher’s exact test. oVEMP abnormalities were found more frequent in aminoglycoside-related bilateral vestibular loss (BVL compared with Menière’s disease (91.7 vs. 54.6%, p = 0.039. Hierarchical cluster analysis indicated distinct patterns of vestibular end-organ impairment, showing that the results for the same end-organs on both sides are more similar than to other end-organs. Relative sparing of anterior-canal function was reflected in late merging with the other end-organs, emphasizing their distinct state. An anatomically corresponding pattern of SCC/otolith hypofunction was present in 60.4% (oVEMPs vs. horizontal SCCs, 34.7% (oVEMPs vs. anterior SCCs, and 48.5% (cVEMPs vs. posterior SCCs of cases. Average (±1 SD number of damaged sensors was 6.8 ± 2.2 out of 10

  10. Single versus combination intravenous anti-pseudomonal antibiotic therapy for people with cystic fibrosis.

    Science.gov (United States)

    Elphick, Heather E; Scott, Alison

    2016-12-01

    Choice of antibiotic, and the use of single or combined therapy are controversial areas in the treatment of respiratory infection due to Pseudomonas aeruginosa in cystic fibrosis (CF). Advantages of combination therapy include wider range of modes of action, possible synergy and reduction of resistant organisms; advantages of monotherapy include lower cost, ease of administration and reduction of drug-related toxicity. Current evidence does not provide a clear answer and the use of intravenous antibiotic therapy in cystic fibrosis requires further evaluation. This is an update of a previously published review. To assess the effectiveness of single compared to combination intravenous anti-pseudomonal antibiotic therapy for treating people with cystic fibrosis. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of the Group's Trials Register: 14 October 2016. Randomised controlled trials (RCTs) comparing a single intravenous anti-pseudomonal antibiotic with a combination of that antibiotic plus a second anti-pseudomonal antibiotic in people with CF. Two authors independently assessed trial quality and extracted data. We identified 45 trials, of which eight trials (356 participants) comparing a single anti-pseudomonal agent to a combination of the same antibiotic and one other, were included.There was a wide variation in the individual antibiotics used in each trial. In total, the trials included seven comparisons of a beta-lactam antibiotic (penicillin-related or third generation cephalosporin) with a beta-lactam-aminoglycoside combination and three comparisons of an aminoglycoside with a beta-lactam-aminoglycoside combination. These two groups of trials were analysed as separate subgroups.There was considerable heterogeneity amongst these trials

  11. Mitochondrial haplotype and phenotype of 13 Chinese families may suggest multi-original evolution of mitochondrial C1494T mutation.

    Science.gov (United States)

    Zhu, Yuhua; Li, Qi; Chen, Zhengyi; Kun, Yao; Liu, Lijia; Liu, Xin; Yuan, Huijun; Zhai, Suoqiang; Han, Dongyi; Dai, Pu

    2009-11-01

    Mutations in mitochondrial DNA (mtDNA) are associated with sensorineural hearing loss. In this study, we traced the origin of the 12S rRNA C1494T mutation through analysis of the clinical, genetic, and molecular characteristics of 13 Han Chinese pedigrees with aminoglycoside-induced and non-syndromic bilateral hearing loss that were selected by C1494T screening in 3133 subjects with non-syndromic hearing impairment from 27 regions of China (13/3133). Clinical evaluation revealed the variable phenotypes of hearing impairment including severity, age-of-onset, and audiometric configuration in these subjects. Through the whole mitochondrial genome DNA sequence analysis, we identified two evolutionarily conservative variants in protein-coding genes: tRNA(Ala) T 5628C and tRNA(Tyr) A5836G mutations. However, the pedigrees with these mutations did not have a higher or lower penetrance of deafness than in other pedigrees. These results suggested that both T 5628C and A5836G mutations might not significantly modify the manifestation of the C1494T mutation. Sequencing analysis of the whole mitochondrial genome of the probands showed that 13 pedigrees from seven different provinces were classified into 10 haplogroups by the distinct sets of mtDNA polymorphisms, including haplogroups A, B, D, D4, D4b2, F1, M, M7c, N9a1, and H2b. This result suggested that the C1494T mutation occurred sporadically with multi-origins through the evolution of the mtDNA in China, and these mtDNA haplogroup-specific variants may not play an important role in the phenotypic expression of the C1494T mutation in these Chinese families with different penetrance of hearing loss. In addition, the lack of a significant mutation in the GJB2 gene ruled out the possible involvement of GJB2 in the phenotypic expression of the C1494T mutation in those affected subjects. Therefore, the aminoglycosides is solo well-established factor to contribute to the deafness manifestation of the C1494T mutation, and

  12. 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

  13. Novel gentamicin resistance genes in Campylobacter isolated from humans and retail meats in the USA.

    Science.gov (United States)

    Zhao, Shaohua; Mukherjee, Sampa; Chen, Yuansha; Li, Cong; Young, Shenia; Warren, Melissa; Abbott, Jason; Friedman, Sharon; Kabera, Claudine; Karlsson, Maria; McDermott, Patrick F

    2015-05-01

    To understand the molecular epidemiology of gentamicin-resistant Campylobacter and investigate aminoglycoside resistance mechanisms. One-hundred-and-fifty-one gentamicin-resistant Campylobacter isolates from humans (n = 38 Campylobacter jejuni; n = 41, Campylobacter coli) and retail chickens (n = 72 C. coli), were screened for the presence of gentamicin resistance genes by PCR and subtyped using PFGE. A subset of the isolates (n = 41) was analysed using WGS. Nine variants of gentamicin resistance genes were identified: aph(2″)-Ib, Ic, Ig, If, If1, If3, Ih, aac(6')-Ie/aph(2″)-Ia and aac(6')-Ie/aph(2″)-If2. The aph(2″)-Ib, Ic, If1, If3, Ih and aac(6')-Ie/aph(2″)-If2 variants were identified for the first time in Campylobacter. Human isolates showed more diverse aminoglycoside resistance genes than did retail chicken isolates, in which only aph(2″)-Ic and -Ig were identified. The aph(2″)-Ig gene was only gene shared by C. coli isolates from human (n = 27) and retail chicken (n = 69). These isolates displayed the same resistance profile and similar PFGE patterns, suggesting that contaminated retail chicken was probably the source of human C. coli infections. Human isolates were genetically diverse and generally more resistant than the retail chicken isolates. The most frequent co-resistance was to tetracycline (78/79, 98.7%), followed by ciprofloxacin/nalidixic acid (46/79, 58.2%), erythromycin and azithromycin (36/79, 45.6%), telithromycin (32/79, 40.5%) and clindamycin (18/79, 22.8%). All human and retail meat isolates were susceptible to florfenicol. This study demonstrated that several new aminoglycoside resistance genes underlie the recent emergence of gentamicin-resistant Campylobacter, and that, in addition to contaminated retail chicken, other sources have also contributed to gentamicin-resistant Campylobacter infections in humans. Published by Oxford University Press on behalf of the British Society for Antimicrobial

  14. Nocardia transvalensis Disseminated Infection in an Immunocompromised Patient with Idiopathic Thrombocytopenic Purpura

    Directory of Open Access Journals (Sweden)

    Jorge García-Méndez

    2016-01-01

    Full Text Available Nocardia transvalensis complex includes a wide range of microorganisms with specific antimicrobial resistance patterns. N. transvalensis is an unusual Nocardia species. However, it must be differentiated due to its natural resistance to aminoglycosides while other Nocardia species are susceptible. The present report describes a Nocardia species involved in an uncommon clinical case of a patient with idiopathic thrombocytopenic purpura and pulmonary nocardiosis. Microbiological and molecular techniques based on the sequencing of the 16S rRNA gene allowed diagnosis of Nocardia transvalensis sensu stricto. The successful treatment was based on trimethoprim-sulfamethoxazole and other drugs. We conclude that molecular identification of Nocardia species is a valuable technique to guide good treatment and prognosis and recommend its use for daily bases diagnosis.

  15. Overexpression of the mitochondrial methyltransferase TFB1M in the mouse does not impact mitoribosomal methylation status or hearing

    DEFF Research Database (Denmark)

    Lee, Seungmin; Rose, Simon; Metodiev, Metodi D

    2015-01-01

    Mitochondrial dysfunction is a well-established cause of sensorineural deafness, but the pathophysiological events are poorly understood. Non-syndromic deafness and predisposition to aminoglycoside-induced deafness can be caused by specific mutations in the 12S rRNA gene of mtDNA and are thus...... by 'hypermethylation' of two conserved adenosines of 12S rRNA in the mitoribosome is of key pathophysiological importance in sensorineural deafness. In support for this concept, it was reported that overexpression of the essential mitochondrial methyltransferase TFB1M in the mouse was sufficient to induce...... mitoribosomal hypermethylation and deafness. At variance with this model, we show here that 12S rRNA is near fully methylated in vivo in the mouse and thus cannot be further methylated to any significant extent. Furthermore, bacterial artificial chromosome transgenic mice overexpressing TFB1M have no increase...

  16. Method of Selection of Bacteria Antibiotic Resistance Genes Based on Clustering of Similar Nucleotide Sequences.

    Science.gov (United States)

    Balashov, I S; Naumov, V A; Borovikov, P I; Gordeev, A B; Dubodelov, D V; Lyubasovskaya, L A; Rodchenko, Yu V; Bystritskii, A A; Aleksandrova, N V; Trofimov, D Yu; Priputnevich, T V

    2017-10-01

    A new method for selection of bacterium antibiotic resistance genes is proposed and tested for solving the problems related to selection of primers for PCR assay. The method implies clustering of similar nucleotide sequences and selection of group primers for all genes of each cluster. Clustering of resistance genes for six groups of antibiotics (aminoglycosides, β-lactams, fluoroquinolones, glycopeptides, macrolides and lincosamides, and fusidic acid) was performed. The method was tested for 81 strains of bacteria of different genera isolated from patients (K. pneumoniae, Staphylococcus spp., S. agalactiae, E. faecalis, E. coli, and G. vaginalis). The results obtained by us are comparable to those in the selection of individual genes; this allows reducing the number of primers necessary for maximum coverage of the known antibiotic resistance genes during PCR analysis.

  17. USAGE RATE OF THE UNLICENSED MEDICATIONS IN NEONATOLOGY: DATA OF THE PHARMACO EPIDEMIOLOGICAL RESEARCH

    Directory of Open Access Journals (Sweden)

    A.S. Kolbin

    2007-01-01

    Full Text Available In recent years clinical pharmacologists working in the field of pediatrics all across the world scrutinize the application issues of unlicensed medications among children. Based on the example of a group of patients consisting of 449 premature infants and with the aid of the pharma coepidemiological research, the authors showed the usage rate of unlicensed anti infectious medications in neonatology. The analysis embraced the 9 year long period of work of the largest neonatal center in northwest. As a result they uncovered that the anti infectious medications which were prescribed most often were aminoglycoside and cephalosporin antibiotics. The applied medications were referred to the unlicensed in neonatology in 21% of cases, and in 8% of cases they were used off label. Further more, it was noted that there was a general trend towards the considerable increase of application of the banned medications for the analyzed period.Key words: very low birth infants, unlicensed drugs.

  18. Analysis of the Kanamycin in Raw Milk Using the Suspension Array

    Directory of Open Access Journals (Sweden)

    Yanfei Wang

    2013-01-01

    Full Text Available With the monoclonal antibody against kanamycin being prepared successfully, a bead-based indirect competitive fluorescent immunoassay was developed to detect kanamycin in milk. The fact that there was no significant cross-reaction with other aminoglycoside antibiotics implied that the monoclonal antibody was highly specific for kanamycin. The limit of detection (LOD and the 50% inhibition concentration (IC50 in raw milk were 3.2 ng/mL and 52.5 ng/mL, respectively. Using the method developed in this study, the kanamycin concentrations were monitored in raw milk after the intramuscular administration of kanamycin in sick cows. Compared to the conventional enzyme-linked immunosorbent assay (ELISA, the method using the suspension array system was more sensitive. The results obtained in the present study showed a good correlation with that of the ELISA.

  19. Enabling techniques in the search for new antibiotics: Combinatorial biosynthesis of sugar-containing antibiotics.

    Science.gov (United States)

    Park, Je Won; Nam, Sang-Jip; Yoon, Yeo Joon

    2017-06-15

    Nature has a talent for inventing a vast number of natural products, including hybrids generated by blending different scaffolds, resulting in a myriad of bioactive chemical entities. Herein, we review the highlights and recent trends (2010-2016) in the combinatorial biosynthesis of sugar-containing antibiotics where nature's structural diversification capabilities are exploited to enable the creation of new anti-infective and anti-proliferative drugs. In this review, we describe the modern combinatorial biosynthetic approaches for polyketide synthase-derived complex and aromatic polyketides, non-ribosomal peptide synthetase-directed lipo-/glycopeptides, aminoglycosides, nucleoside antibiotics, and alkaloids, along with their therapeutic potential. Finally, we present the feasible nexus between combinatorial biosynthesis, systems biology, and synthetic biology as a toolbox to provide new antibiotics that will be indispensable in the post-antibiotic era. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Quorum Sensing-Regulated Phenol-Soluble Modulins Limit Persister Cell Populations in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Bojer, Martin S; Lindemose, Søren; Vestergaard, Martin

    2018-01-01

    Incomplete killing of bacterial pathogens by antibiotics is an underlying cause of treatment failure and accompanying complications. Among those avoiding chemotherapy are persisters being individual cells in a population that for extended periods of time survive high antibiotic concentrations...... proposedly by being in a quiescent state refractory to antibiotic killing. While investigating the human pathogenStaphylococcus aureusand the influence of growth phase on persister formation, we noted that spent supernatants of stationary phase cultures ofS. aureusorS. epidermidis, but not of distantly...... properties; however, the persister reducing activity was specifically linked to synthesis of the PSMα family. Correspondingly, a high-persister phenotype of a PSMα mutant was observed upon fluoroquinolone or aminoglycoside challenge, demonstrating that the persister reducing activity of PSMs can...