WorldWideScience

Sample records for aminoglycoside antibiotic activity

  1. Antibiotic Binding Drives Catalytic Activation of Aminoglycoside Kinase APH(2″)-Ia.

    Science.gov (United States)

    Caldwell, Shane J; Huang, Yue; Berghuis, Albert M

    2016-06-01

    APH(2″)-Ia is a widely disseminated resistance factor frequently found in clinical isolates of Staphylococcus aureus and pathogenic enterococci, where it is constitutively expressed. APH(2″)-Ia confers high-level resistance to gentamicin and related aminoglycosides through phosphorylation of the antibiotic using guanosine triphosphate (GTP) as phosphate donor. We have determined crystal structures of the APH(2″)-Ia in complex with GTP analogs, guanosine diphosphate, and aminoglycosides. These structures collectively demonstrate that aminoglycoside binding to the GTP-bound kinase drives conformational changes that bring distant regions of the protein into contact. These changes in turn drive a switch of the triphosphate cofactor from an inactive, stabilized conformation to a catalytically competent active conformation. This switch has not been previously reported for antibiotic kinases or for the structurally related eukaryotic protein kinases. This catalytic triphosphate switch presents a means by which the enzyme can curtail wasteful hydrolysis of GTP in the absence of aminoglycosides, providing an evolutionary advantage to this enzyme.

  2. Termite usage associated with antibiotic therapy: enhancement of aminoglycoside antibiotic activity by natural products of Nasutitermes corniger (Motschulsky 1855

    Directory of Open Access Journals (Sweden)

    Almeida-Filho Geraldo G

    2009-09-01

    Full Text Available Abstract Background Several species from Insecta are used as remedies. Among these species, the termite Nasutitermes corniger is commonly used in traditional medicine in Northeast Brazil. The present work tests the modifying antibiotic activity of Nasutitermes corniger, a termite used in folk medicine in Northeastern region of Brazil. Methods Chlorpromazine and decocts of N. corniger were collected from two different plant species used in the traditional medicine were tested for their antimicrobial activity against strains of Escherichia coli resistant to aminoglycosides. The growth of two bacterial strains of E. coli was tested using decocts and chlorpromazine alone or associeted with aminogycosides. Results The MIC and MBC values were ≥1024 μg/ml for both strains of E. coli assayed. A significant synergism was observed between both decocts and chlorpromazine when assyed with neomycin. This synergism with neomycin indicates the involvement of an efflux system in the resistance to this aminoglycoside. Conclusion Therefore it is suggested that natural products from N. corniger could be used as a source of zoo-derived natural products with modifying antibiotic activity to aminoglycosides, being a new weapon against the bacterial resistance to antibiotics.

  3. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Purdy Drew, Kirstin R.; Sanders, Lori K.; Culumber, Zachary W.; Zribi, Olena; Wong, Gerard C.L.; (UIUC)

    2009-06-17

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  4. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Drew, K.R.Purdy; Sanders, L.K.; Culumber, Z.W.; Zribi, O.; Wong, G.C.L.

    2009-05-21

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

  5. Cationic Amphiphiles Increase Activity of Aminoglycoside Antibiotic Tobramycin in the Presence of Airway Polyelectrolytes

    International Nuclear Information System (INIS)

    It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers

  6. DNA-Aptamers Binding Aminoglycoside Antibiotics

    Directory of Open Access Journals (Sweden)

    Nadia Nikolaus

    2014-02-01

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

  7. Audiological Management of Patients Receiving Aminoglycoside Antibiotics

    Science.gov (United States)

    Konrad-Martin, Dawn; Wilmington, Debra J.; Gordon, Jane S.; Reavis, Kelly M.; Fausti, Stephen A.

    2005-01-01

    Aminoglycoside antibiotics, commonly prescribed for adults and children to treat a wide range of bacterial infections, are potentially ototoxic, often causing irreversible damage to the auditory and vestibular systems. Ototoxic hearing loss usually begins at the higher frequencies and can progress to lower frequencies necessary for understanding…

  8. Aminoglycoside antibiotics and autism: a speculative hypothesis

    Directory of Open Access Journals (Sweden)

    Manev Hari

    2001-10-01

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

  9. 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.

  10. High throughput LSPR and SERS analysis of aminoglycoside antibiotics.

    Science.gov (United States)

    McKeating, Kristy S; Couture, Maxime; Dinel, Marie-Pier; Garneau-Tsodikova, Sylvie; Masson, Jean-Francois

    2016-08-15

    Aminoglycoside antibiotics are used in the treatment of infections caused by Gram-negative bacteria, and are often dispensed only in severe cases due to their adverse side effects. Patients undergoing treatment with these antibiotics are therefore commonly subjected to therapeutic drug monitoring (TDM) to ensure a safe and effective personalised dosage. The ability to detect these antibiotics in a rapid and sensitive manner in human fluids is therefore of the utmost importance in order to provide effective monitoring of these drugs, which could potentially allow for a more widespread use of this class of antibiotics. Herein, we report on the detection of various aminoglycosides, by exploiting their ability to aggregate gold nanoparticles. The number and position of the amino groups of aminoglycoside antibiotics controlled the aggregation process. We investigated the complementary techniques of surface enhanced Raman spectroscopy (SERS) and localized surface plasmon resonance (LSPR) for dual detection of these aminoglycoside antibiotics and performed an in-depth study of the feasibility of carrying out TDM of tobramycin using a platform amenable to high throughput analysis. Herein, we also demonstrate dual detection of tobramycin using both LSPR and SERS in a single platform and within the clinically relevant concentration range needed for TDM of this particular aminoglycoside. Additionally we provide evidence that tobramycin can be detected in spiked human serum using only functionalised nanoparticles and SERS analysis. PMID:27412506

  11. DNA-Aptamers Binding Aminoglycoside Antibiotics

    OpenAIRE

    Nadia Nikolaus; Beate Strehlitz

    2014-01-01

    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 aminog...

  12. 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

    2015-01-01

    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

  13. 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

    2015-01-01

    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

  14. Toggled RNA Aptamers Against Aminoglycosides Allowing Facile Detection of Antibiotics Using Gold Nanoparticle Assays

    OpenAIRE

    Derbyshire, Nicola; White, Simon J.; Bunka, David H. J.; Song, Lei; Stead, Sara; Tarbin, Jonathan; Sharman, Matthew; Zhou, Dejian; Stockley, Peter G.

    2012-01-01

    We have used systematic evolution of ligands by exponential enrichment (SELEX) to isolate RNA aptamers against aminoglycoside antibiotics. The SELEX rounds were toggled against four pairs of aminoglycosides with the goal of isolating reagents that recognize conserved structural features. The resulting aptamers bind both of their selection targets with nanomolar affinities. They also bind the less structurally related targets, although they show clear specificity for this class of antibiotics....

  15. Phytochemical screening and synergistic interactions between aminoglycosides, selected antibiotics and extracts from the bryophyte Octoblepharum albidum Hedw (Calymperaceae

    Directory of Open Access Journals (Sweden)

    Vidal C.A.S.

    2012-01-01

    Full Text Available This work is the first to describe the modulation of antibiotic activity of the bryophyte Octoblepharum albidum Hedw extract. The antibacterial activity of ethanolic extract of O. albidum (EEOa, alone and in association with aminoglycosides, was determined against six bacterial strains by a microdilution test. The results showed a similar inhibitory activity of EEOa against Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 33018 (MICs 512 μg/mL. The synergistic effect of the extracts and aminoglycosides was also verified. The most pronounced effects were obtained with EEOa + gentamicin against E. coli and EEOa + kanamycin against K. pneumoniae with MICs reduction (128 to 32 μg/mL. The data from this study are indicative of the antibacterial activity of the bryophyte O. albidum extracts and its potential in modifying the resistance of aminoglycosides analyzed.

  16. USMB-induced synergistic enhancement of aminoglycoside antibiotics in biofilms.

    Science.gov (United States)

    Ronan, Evan; Edjiu, Narbeh; Kroukamp, Otini; Wolfaardt, Gideon; Karshafian, Raffi

    2016-07-01

    This study evaluated the effect of combining antibiotics with ultrasound and microbubbles (USMB) toward the eradication of biofilms. Pseudomonas aeruginosa PAO1 biofilms were treated with the antibiotics gentamicin sulfate or streptomycin sulfate, or a combination of USMB with the respective antibiotics. Biofilm structure was quantified using confocal laser scanning microscopy with COMSTAT analysis, while activity was measured as whole-biofilm CO2 production in a continuous-flow biofilm model. The combined antibiotic-USMB treatment significantly impacted biofilm biomass, thickness and surface roughness compared to antibiotics alone (p<0.05). USMB exposure caused the formation of craters (5-20μm in diameter) in the biofilms, and when combined with gentamicin, activity was significantly lower, compared to gentamicin, USMB or untreated controls, respectively. Interestingly, the CO2 production rate following combined streptomycin-USMB treatment was higher than after streptomycin alone, but significantly lower than USMB alone and untreated control. These results show strong evidence of a synergistic effect between antibiotics and USMB, although the varied response to different antibiotics emphasize the need to optimize the USMB exposure conditions to maximize this synergism and ultimately transfer this technology into clinical or industrial practice. PMID:27111871

  17. Sensitivity of ribosomes of the hyperthermophilic bacterium Aquifex pyrophilus to aminoglycoside antibiotics.

    OpenAIRE

    Bocchetta, M; Huber, R.; Cammarano, P

    1996-01-01

    A poly(U)-programmed cell-free system from the hyperthermophilic bacterium Aquifex pyrophilus has been developed, and the susceptibility of Aquifex ribosomes to the miscoding-inducing and inhibitory actions of all known classes of aminoglycoside antibiotics has been assayed at temperatures (75 to 80 degrees C) close to the physiological optimum for cell growth. Unlike Thermotoga maritima ribosomes, which are systematically refractory to all known classes of aminoglycoside compounds (P. Londei...

  18. Introducing Aztreonam The First Monobactam Antibiotic, A Suitable Substitution for the Aminoglycosides

    Directory of Open Access Journals (Sweden)

    A. Jahanshahi M.Khajeh - Karamadeni S. Fazli Bazaz

    1992-07-01

    Full Text Available Aztreonam (Azactam for injection, squibb is the first member of a new and unique class of beta - lactam antibiotics designated by researchers at the Squibb Institute for Medical Research as monobactams (monocyclic bacterially produced beta - lactam antibiotics."nIn this research, for the first time, antimicrobial spectrum of aztrenoam was determined by Disk - Agar Diffusion (250 spp. and Macrodilution Broth Methods (150 Spp."nWe also compared this antibiotic with two routine aminoglycoside antibiotics (Amikacin, Gentamicin in Iran. The most active antibiotic in our study was aztreonam which had MIC50 & MIC90 of 4 & 32 ^g/ml specifically against Pseudomonas aeruginosa."nThis rate for the other aerobic gram - negative bacteria (E. coli, Kleb. pneumoniae, Proteus mirabilis, enterobacter spp., Shigella Spp. and Salmonella Spp. was less than 0.5 & 4 g/ml respectively."nAztreonam's MIC90 for kleb pneumoniae was 8/jg/mI our results were Correlated to the other studies"nAll aerobic gram - negative bacteria has been obtained from the Qhaem's Medical Center in Mashhad - IRAN."nThe results of Disk - Agar Diffusion Method determines that all bacteria were 100% susceptible against aztreonam except Pseudomonas aeruginosa with 83% susceptibility.

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

    Directory of Open Access Journals (Sweden)

    Monteiro A.C.M.

    2003-01-01

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

  20. Role of aromatic rings in the molecular recognition of aminoglycoside antibiotics: implications for drug design.

    Science.gov (United States)

    Vacas, Tatiana; Corzana, Francisco; Jiménez-Osés, Gonzalo; González, Carlos; Gómez, Ana M; Bastida, Agatha; Revuelta, Julia; Asensio, Juan Luis

    2010-09-01

    Aminoglycoside antibiotics participate in a large variety of binding processes involving both RNA and proteins. The description, in recent years, of several clinically relevant aminoglycoside/receptor complexes has greatly stimulated the structural-based design of new bioactive derivatives. Unfortunately, design efforts have frequently met with limited success, reflecting our incomplete understanding of the molecular determinants for the antibiotic recognition. Intriguingly, aromatic rings of the protein/RNA receptors seem to be key actors in this process. Indeed, close inspection of the structural information available reveals that they are frequently involved in CH/pi stacking interactions with sugar/aminocyclitol rings of the antibiotic. While the interaction between neutral carbohydrates and aromatic rings has been studied in detail during past decade, little is known about these contacts when they involve densely charged glycosides. Herein we report a detailed experimental and theoretical analysis of the role played by CH/pi stacking interactions in the molecular recognition of aminoglycosides. Our study aims to determine the influence that the antibiotic polycationic character has on the stability, preferred geometry, and dynamics of these particular contacts. With this purpose, different aminoglycoside/aromatic complexes have been selected as model systems. They varied from simple bimolecular interactions to the more stable intramolecular CH/pi contacts present in designed derivatives. The obtained results highlight the key role played by electrostatic forces and the desolvation of charged groups in the molecular recognition of polycationic glycosides and have clear implications for the design of improved antibiotics.

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

    International Nuclear Information System (INIS)

    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 NaBH4 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

  2. Synergistic Effect of Oleanolic Acid on Aminoglycoside Antibiotics against Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Bora Shin

    Full Text Available Difficulties involved in treating drug-resistant pathogens have created a need for new therapies. In this study, we investigated the possibility of using oleanolic acid (OA, a natural pentacyclic triterpenoid, as a natural adjuvant for antibiotics against Acinetobacter baumannii. High concentrations of OA can kill cells, partly because it generates reactive oxygen species. Measurement of the fractional inhibitory concentration (FIC for OA and time-kill experiments demonstrated that it only synergizes with aminoglycoside antibiotics (e.g., gentamicin, kanamycin. Other classes of antibiotics (e.g., ampicillin, rifampicin, norfloxacin, chloramphenicol, and tetracycline have no interactions with OA. Microarray and quantitative reverse transcription-PCR analysis indicated that genes involved in ATP synthesis and cell membrane permeability, the gene encoding glycosyltransferase, peptidoglycan-related genes, phage-related genes, and DNA repair genes were upregulated under OA. OA highly induces the expression of adk, which encodes an adenylate kinase, and des6, which encodes a linoleoyl-CoA desaturase, and deletion of these genes increased FICs; these observations indicate that adk and des6 are involved in the synergism of OA with aminoglycosides. Data obtained using 8-anilino-1-naphthalenesulfonic acid, fluorescence-conjugated gentamicin, and membrane fatty acid analysis indicates that adk and des6 are involved in changes in membrane permeability. Proton-motive force and ATP synthesis tests show that those genes are also involved in energy metabolism. Taken together, our data show that OA boosts aminoglycoside uptake by changing membrane permeability and energy metabolism in A. baumannii.

  3. Crystal structures of antibiotic-bound complexes of aminoglycoside 2''-phosphotransferase IVa highlight the diversity in substrate binding modes among aminoglycoside kinases.

    Science.gov (United States)

    Shi, Kun; Houston, Douglas R; Berghuis, Albert M

    2011-07-19

    Aminoglycoside 2''-phosphotransferase IVa [APH(2'')-IVa] is a member of a family of bacterial enzymes responsible for medically relevant resistance to antibiotics. APH(2'')-IVa confers high-level resistance against several clinically used aminoglycoside antibiotics in various pathogenic Enterococcus species by phosphorylating the drug, thereby preventing it from binding to its ribosomal target and producing a bactericidal effect. We describe here three crystal structures of APH(2'')-IVa, one in its apo form and two in complex with a bound antibiotic, tobramycin and kanamycin A. The apo structure was refined to a resolution of 2.05 Å, and the APH(2'')-IVa structures with tobramycin and kanamycin A bound were refined to resolutions of 1.80 and 2.15 Å, respectively. Comparison among the structures provides insight concerning the substrate selectivity of this enzyme. In particular, conformational changes upon substrate binding, involving rotational shifts of two distinct segments of the enzyme, are observed. These substrate-induced shifts may also rationalize the altered substrate preference of APH(2'')-IVa in comparison to those of other members of the APH(2'') subfamily, which are structurally closely related. Finally, analysis of the interactions between the enzyme and aminoglycoside reveals a distinct binding mode as compared to the intended ribosomal target. The differences in the pattern of interactions can be utilized as a structural basis for the development of improved aminoglycosides that are not susceptible to these resistance factors.

  4. Natural antioxidant L-carnosine inhibits LPO intensification in structures of the auditory analyzer under conditions of chronic exposure to aminoglycoside antibiotics.

    Science.gov (United States)

    Zhuravskii, S G; Aleksandrova, L A; Sirot, V S; Ivanov, S A

    2004-10-01

    Intragastric administration of L-carnosine suspension to Wistar-Kyoto rats 3 days before and after 7-day course of intraperitoneal injections of ototoxic aminoglycoside antibiotic kanamycin compensated expenditures of tissue antioxidant systems and significantly eliminated kanamycin-induced intensification of MDA production in tissues of the membrane part of the cochlea and in the auditory cortex of the temporal lobe. L-NAME (competitive NO synthase inhibitor) also inhibited LPO, increased total antioxidant activity, and decreased ototoxicity of kanamycin, which confirms the contribution of NO into LPO intensification under conditions of aminoglycoside treatment. Inhibition of pathological intensification of LPO processes and increase in total antioxidant activity under conditions of induced acute aminoglycoside ototoxicity characterizes L-carnosine as a highly effective otoprotector. PMID:15665945

  5. Investigation on the Mechanism of Exacerbation of Myasthenia Gravis by Aminoglycoside Antibiotics in Mouse Model

    Institute of Scientific and Technical Information of China (English)

    LIU Changqin; HU Fang

    2005-01-01

    Summary: To investigate the underlying mechanism of the exacerbation of myasthenia gravis by aminoglycoside antibiotics. C57/BL6 mice were immunized with acetylcholine receptor (AChR), extracted from electric organ of Narcine timilei according to Xu Haopeng's methods, in complete Fruend's adjuvant (CFA) to establish experimental autoimmune myasthenia gravis (EAMG). EAMG mice were divided randomly into 5 groups: MG group, NS group and three antibiotics groups. The clinical symptom scores of mice were evaluated on d7 after the last immunization and d14 of antibiotics treatment. Repetitive nerve stimulation (RNS) was performed and the levels of anti-AChR antibody (AChR-Ab) were tested at the same time. The mean clinical symptom grades of gentamycin group (1.312, 2.067), amikacin group (1.111, 1.889) and etimicin group (1.263, 1.632) were significantly higher than those of MG group (1.000, 1.200) (P<0.05). The positive rates of RNS of three antibiotics groups were 69.23 %, 58.82 % and 63.16 % respectively, which were significantly higher than those of MG group and NS group (40.00 %, 40.00 %, P<0.05). The AChR-Ab level in serum and the expression of AChR on neuromuscular junction (NMJ) of mice in three antibiotics groups were also higher than those of MG group. Our results indicated that aminoglycoside antibiotics could aggravate the symptom of myasthenia gravis. The exacerbation of myasthenia gravis by these antibiotics probably involves competitively restraining the release of acetylcholine from presynaptic membrane, impairing the depolarization of postsynaptic membrane, depressing the irritability of myocyte membrane around the end-plate membrane and consequently leading to the blockade of neuromuscular junction.

  6. The comparative effects of aminoglycoside antibiotics and muscle relaxants on electrical field stimulation response in rat bladder smooth muscle.

    Science.gov (United States)

    Min, Chang Ho; Min, Young Sil; Lee, Sang Joon; Sohn, Uy Dong

    2016-06-01

    It has been reported that several aminoglycoside antibiotics have a potential of prolonging the action of non-depolarizing muscle relaxants by drug interactions acting pre-synaptically to inhibit acetylcholine release, but antibiotics itself also have a strong effect on relaxing the smooth muscle. In this study, four antibiotics of aminoglycosides such as gentamicin, streptomycin, kanamycin and neomycin were compared with skeletal muscle relaxants baclofen, tubocurarine, pancuronium and succinylcholine, and a smooth muscle relaxant, papaverine. The muscle strips isolated from the rat bladder were stimulated with pulse trains of 40 V in amplitude and 10 s in duration, with pulse duration of 1 ms at the frequency of 1-8 Hz, at 1, 2, 4, 6, 8 Hz respectively. To test the effect of four antibiotics on bladder smooth muscle relaxation, each of them was treated cumulatively from 1 μM to 0.1 mM with an interval of 5 min. Among the four antibiotics, gentamicin and neomycin inhibited the EFS response. The skeletal muscle relaxants (baclofen, tubocurarine, pancuronium and succinylcholine) and inhibitory neurotransmitters (GABA and glycine) did not show any significant effect. However, papaverine, had a significant effect in the relaxation of the smooth muscle. It was suggested that the aminoglycoside antibiotics have inhibitory effect on the bladder smooth muscle. PMID:27260628

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

    Science.gov (United States)

    Tiwow, Vanny M. A.

    2014-03-01

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

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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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

  10. Combinations of β-lactam or aminoglycoside antibiotics with plectasin are synergistic against methicillin-sensitive and methicillin-resistant Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Yanmin Hu

    Full Text Available 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

  11. Synergistic interaction of PMAP-36 and PRW4 with aminoglycoside antibiotics and their antibacterial mechanism.

    Science.gov (United States)

    Wang, Zeyun; Zhang, Licong; Wang, Jue; Wei, Dandan; Shi, Baoming; Shan, Anshan

    2014-12-01

    The antimicrobial peptide PMAP-36 is a highly cationic and amphipathic α-helical peptide. PRW4 is a truncated analog that replaces paired lysine residues with tryptophan along the N-terminal and deletes the C-terminal hydrophobic tail of PMAP-36. Studies on the two peptides have already been performed. However, whether there is a synergistic effect with antibiotics has not been investigated, and the study of the antibacterial mechanism of the peptides is inadequate. In this study, antibiotic-peptide combinations were tested against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, and the confocal laser scanning microscopy (LSCM) and DNA gel retardation were measured. The results indicated synergy between the peptides and gentamicin when tested against E. coli [fractional lethal concentration (FLC) peptides and gentamicin against S. aureus (0.5 peptides against E. coli and S. aureus (1 DNA binding suggest that PMAP-36 was able to translocate across the bacterial membranes and interact with intracellular DNA, but PRW4 presented no DNA-binding ability. These results indicate that the combination of PMAP-36 and PRW4 with aminoglycosides may provide useful information for clinical application, and the antibacterial mechanism of peptides likely does not solely involve cytoplasmic-membrane permeabilization.

  12. Mutations in eukaryotic 18S ribosomal RNA affect translational fidelity and resistance to aminoglycoside antibiotics.

    Science.gov (United States)

    Chernoff, Y O; Vincent, A; Liebman, S W

    1994-02-15

    Mutations have been created in the Saccharomyces cerevisiae 18S rRNA gene that correspond to those known to be involved in the control of translational fidelity or antibiotic resistance in prokaryotes. Yeast strains, in which essentially all chromosomal rDNA repeats are deleted and all cellular rRNAs are encoded by plasmid, have been constructed that contain only mutant 18S rRNA. In Escherichia coli, a C-->U substitution at position 912 of the small subunit rRNA causes streptomycin resistance. Eukaryotes normally carry U at the corresponding position and are naturally resistant to streptomycin. We show that a U-->C transition (rdn-4) at this position of the yeast 18S rRNA gene decreases resistance to streptomycin. The rdn-4 mutation also increases resistance to paromomycin and G-418, and inhibits nonsense suppression induced by paromomycin. The same phenotypes, as well as a slow growth phenotype, are also associated with rdn-2, whose prokaryotic counterpart, 517 G-->A, manifests itself as a suppressor rather than an antisuppressor. Neither rdn-2- nor rdn-4-related phenotypes could be detected in the presence of the normal level of wild-type rDNA repeats. Our data demonstrate that eukaryotic rRNA is involved in the control of translational fidelity, and indicate that rRNA features important for interactions with aminoglycosides have been conserved throughout evolution.

  13. Non-derivatization approach to high-performance liquid chromatography-fluorescence detection for aminoglycoside antibiotics based on a ligand displacement reaction.

    Science.gov (United States)

    Yang, M; Tomellini, S A

    2001-12-21

    An indirect fluorescence detection method has been developed for detecting the aminoglycoside antibiotics following chromatographic separation. This approach to detection is based on a displacement reaction between the aminoglycosides and a copper(II)-L-tryptophan (L-Trp) complex, Cu(L-Trp)2. The aminoglycosides, which contain multiple amino groups, have strong affinities for the Cu(II) ion and displace L-Trp from the Cu(L-Trp)2 complex. The resulting increase in L-Trp fluorescence, which is quenched when coordinated to Cu(II), is indicative of the presence of the aminoglycoside. Fluorescence titration data indicate that there is a stoichiometric ratio of 1:1 between the reaction of the aminoglycosides with Cu(L-Trp)2. This HPLC detection scheme is implemented postcolumn by mixing a buffered Cu(L-Trp)2 solution with the column eluent prior to detection. The aminoglycosides were separated with the use of a column packed with a polymeric strong cation-exchanger. Separation and detection variables were optimized and are discussed. The detection limits for the aminoglycosides tested ranged from 4.2 to 14.5 ng injected (S/N=3). A linear working curve was achieved for amikacin in the range of 29-586 ng for a six point linearity test. The developed separation and detection scheme was further tested by analyzing commercial pharmaceutical formulations of these antibiotics. PMID:11806546

  14. 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

  15. 30S Subunit-Dependent Activation of the Sorangium cellulosum So ce56 Aminoglycoside Resistance-Conferring 16S rRNA Methyltransferase Kmr

    Science.gov (United States)

    Savic, Miloje; Sunita, S.; Zelinskaya, Natalia; Desai, Pooja M.; Macmaster, Rachel; Vinal, Kellie

    2015-01-01

    Methylation of bacterial 16S rRNA within the ribosomal decoding center confers exceptionally high resistance to aminoglycoside antibiotics. This resistance mechanism is exploited by aminoglycoside producers for self-protection while functionally equivalent methyltransferases have been acquired by human and animal pathogenic bacteria. Here, we report structural and functional analyses of the Sorangium cellulosum So ce56 aminoglycoside resistance-conferring methyltransferase Kmr. Our results demonstrate that Kmr is a 16S rRNA methyltransferase acting at residue A1408 to confer a canonical aminoglycoside resistance spectrum in Escherichia coli. Kmr possesses a class I methyltransferase core fold but with dramatic differences in the regions which augment this structure to confer substrate specificity in functionally related enzymes. Most strikingly, the region linking core β-strands 6 and 7, which forms part of the S-adenosyl-l-methionine (SAM) binding pocket and contributes to base flipping by the m1A1408 methyltransferase NpmA, is disordered in Kmr, correlating with an exceptionally weak affinity for SAM. Kmr is unexpectedly insensitive to substitutions of residues critical for activity of other 16S rRNA (A1408) methyltransferases and also to the effects of by-product inhibition by S-adenosylhomocysteine (SAH). Collectively, our results indicate that adoption of a catalytically competent Kmr conformation and binding of the obligatory cosubstrate SAM must be induced by interaction with the 30S subunit substrate. PMID:25733511

  16. Crystallographic Studies of Two Bacterial AntibioticResistance Enzymes: Aminoglycoside Phosphotransferase (2')-Ic and GES-1\\beta-lactamase

    Energy Technology Data Exchange (ETDEWEB)

    Brynes, Laura; /Rensselaer Poly.

    2007-10-31

    Guiana Extended-Spectrum-1 (GES-1) and Aminoglycoside phosphotransferase (2')-Ic (APH(2')-Ic) are two bacteria-produced enzymes that essentially perform the same task: they provide resistance to an array of antibiotics. Both enzymes are part of a growing resistance problem in the medical world. In order to overcome the ever-growing arsenal of antibiotic-resistance enzymes, it is necessary to understand the molecular basis of their action. Accurate structures of these proteins have become an invaluable tool to do this. Using protein crystallography techniques and X-ray diffraction, the protein structure of GES-1 bound to imipenem (an inhibitor) has been solved. Also, APH(2')-Ic has been successfully crystallized, but its structure was unable to be solved using molecular replacement using APH(2')-Ib as a search model. The structure of GES-1, with bound imipenem was solved to a resolution of 1.89A, and though the inhibitor is bound with only moderate occupancy, the structure shows crucial interactions inside the active site that render the enzyme unable to complete the hydrolysis of the {beta}-lactam ring. The APH(2')-Ic dataset could not be matched to the model, APH(2')-Ib, with which it shares 25% sequence identity. The structural information gained from GES-1, and future studies using isomorphous replacement to solve the APH(2')-Ic structure can aid directly to the creation of novel drugs to combat both of these classes of resistance enzymes.

  17. Special characteristics of fluorescence and resonance Rayleigh scattering for cadmium telluride nanocrystal aqueous solution and its interactions with aminoglycoside antibiotics

    Institute of Scientific and Technical Information of China (English)

    LI TaiShan; LIU ShaoPu; LIU ZhongFang; HU XiaoLi; ZHANG LiPing

    2009-01-01

    CdTe nanocrystals (CdTe NCs) were achieved by reaction of CdCl2 with KHTe solution and were capped with sodium mercaptoacetate. The product was detected by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), fluorescence spectra, ultraviolet-visible spectra and X-ray diffraction (XRD). The CdTe NCs are of cubic structure and the average size is about 5 nm. The fluorescence quantum yield of CdTe NCs aqueous solution increased from 37% to 97% after 20 d under room light. The maximum λem of fluorescence changed from 543 nm to 510 nm and the blue shift was 33 nm. CdTe NCs aqueous solution can be steady for at least 10 months at 4℃ in a refrigerator. The resonance Rayleigh scattering (RRS) of CdTe NCs in the aqueous solution was investigated. The maximum scattering peak was located at about 554 nm. The interactions of CdTe NCs with amikacin sulfate (AS) and micronomicin sulfate (MS) were in-vestigated respectively. The effects of AS and MS on fluorescence and RRS of CdTe NCs were analyzed. It was found that AS and MS quenched the photoluminescence of CdTe NCs and enhanced RRS of CdTe NCs. Under optimum conditions, there are linear relationships between quenching intensity (F0-F), intensity of RRS (1-10) and concentration of AS and MS. The detection limits (3σ) of AS and MS are re-spectively 3.4 ng.mL-1 and 2.6 ng.mL-1 by the fluorescence quenching method, and 15.2 ng.mL-1 and 14.0 ng.mL-1 by the RRS method. The methods have high sensitivity, thus CdTe NCs may be used as fluorescence probes and RRS probes for the detection of aminoglycoside antibiotics.

  18. Rapid analysis of aminoglycoside antibiotics in bovine tissues using disposable pipette extraction and ultrahigh performance liquid chromatography - tandem mass spectrometry

    Science.gov (United States)

    A high-throughput qualitative screening and identification method for 9 aminoglycosides of regulatory interest has been developed, validated, and implemented for bovine kidney, liver, and muscle tissues. The method involves extraction at previously validated conditions, cleanup using disposable pip...

  19. An aminoglycoside sensing riboswitch controls the expression of aminoglycoside resistance acetyltransferase and adenyltransferases.

    Science.gov (United States)

    Chen, Dongrong; Murchie, Alastair I H

    2014-10-01

    The emergence of antibiotic resistance in human pathogens is an increasing threat to public health. The fundamental mechanisms that control the high levels of expression of antibiotic resistance genes are not yet completely understood. The aminoglycosides are one of the earliest classes of antibiotics that were introduced in the 1940s. In the clinic aminoglycoside resistance is conferred most commonly through enzymatic modification of the drug although resistance through enzymatic modification of the target rRNA through methylation or the overexpression of efflux pumps is also appearing. An aminoglycoside sensing riboswitch has been identified that controls expression of the aminoglycoside resistance genes that encode the aminoglycoside acetyltransferase (AAC) and aminoglycoside nucleotidyltransferase (ANT) (adenyltransferase (AAD)) enzymes. AAC and ANT cause resistance to aminoglycoside antibiotics through modification of the drugs. Expression of the AAC and ANT resistance genes is regulated by aminoglycoside binding to the 5' leader RNA of the aac/aad genes. The aminoglycoside sensing RNA is also associated with the integron cassette system that captures antibiotic resistance genes. Specific aminoglycoside binding to the leader RNA induces a structural transition in the leader RNA, and consequently induction of resistance protein expression. Reporter gene expression, direct measurements of drug RNA binding, chemical probing and UV cross-linking combined with mutational analysis demonstrated that the leader RNA functioned as an aminoglycoside sensing riboswitch in which drug binding to the leader RNA leads to the induction of aminoglycoside antibiotic resistance. This article is part of a Special Issue entitled: Riboswitches. PMID:24631585

  20. Structural and Molecular Basis for Resistance to Aminoglycoside Antibiotics by the Adenylyltransferase ANT(2″)-Ia

    OpenAIRE

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

    2015-01-01

    ABSTRACT   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...

  1. [PK/PD modeling of aminoglycoside nephrotoxicity].

    Science.gov (United States)

    Rougier, F; Corvaisier, S; Ducher, M; Claude, D; Jelliffe, R W; Maire, P

    2003-06-01

    Aminoglycosides are bactericidial antibiotics with a serum concentration-dependent activity. They are mainly eliminated by the kidneys and the main difficulty arising in clinical use is their uptake by the renal cortex which leads to nephrotoxicity. An ototoxicity is also reported. We propose a PK/PD modelling of aminoglycoside nephrotoxicity which unifies more fourty years of physiological knowledge. This deterministic model successively describes the pharmacokinetics of aminoglycosides, their storage into renal cortex, their effect on renal cells, their consequences on the renal function through tubuloglomerular feedback and the changes in the serum concentrations of creatinine that is considered as a toxicity marker. The simulation of the model displays the leading effect of the shape and daily-time of administration schedule on the search for minimizing toxicity.

  2. Mechanistic studies of copper(II)-aminoglycoside mediated DNA damage and magnesium catalyzed nuclease activity of hammerhead ribozyme

    Science.gov (United States)

    Patwardhan, Anjali A.

    The antibacterial activity of aminoglycosides stems from their high affinity binding to the 16S rRNA in bacteria resulting in inhibition of protein synthesis. Used to treat acute bacterial infections these antibiotics have limited applications due to their high dosage requirements and the emergence of resistant strains. We have synthesized and characterized Cu(II) derivatives of the aminoglycosides, kanamycin A, tobramycin, neamine, kanamycin B, neomycin B, and paromomycin. The first three exhibit preferential and tight binding to Cu(II) as against neomycin B and kanamycin B and paromomycin. EPR of frozen solutions and UV-visible spectroscopy suggest a change in geometry around the Cu(II) but the stabilities of the complexes in water differ. These copper derivatives efficiently cleave plasmid DNA at micromolar concentrations (hydrolytic) and at nanomolar concentrations in the presence co-reactants like hydrogen peroxide or ascorbic acid. Hydrolysis is multi turnover and exhibits Michelis-Menten kinetics with enzyme-like behavior whereas oxidative cleavage is highly specific with C-4' H abstraction resulting in characteristic base propenal and nucleotide base products. Hydroxyl radicals generated are copper based and are generated in close proximity of the substrate. Hammerhead ribozymes are selectively hydrolyzed in the presence of divalent ions with Mg2+ being the metal ion of choice in vivo . Our studies with complex ions like cobalt hexaammine and fac-triamminetriaquochromium(III) establish outer sphere interactions of Mg2+ with the hammerhead in the catalytic site. There are two sets of sites, one structural and one catalytic. Complex ions in the catalytic site and divalent ions in the structural site result in a slow but active hammerhead ribozyme suggesting that the complex ions are not inhibitory, contrary to what was suggested previously.

  3. Special characteristics of fluorescence and resonance Rayleigh scattering for cadmium telluride nanocrystal aqueous solution and its interactions with aminoglycoside antibiotics

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    CdTe nanocrystals(CdTe NCs) were achieved by reaction of CdCl2 with KHTe solution and were capped with sodium mercaptoacetate.The product was detected by transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM),energy dispersive spectroscopy(EDS),fluorescence spectra,ultraviolet-visible spectra and X-ray diffraction(XRD).The CdTe NCs are of cubic structure and the average size is about 5 nm.The fluorescence quantum yield of CdTe NCs aqueous solution increased from 37% to 97% after 20 d under room light.The maximum λem of fluorescence changed from 543 nm to 510 nm and the blue shift was 33 nm.CdTe NCs aqueous solution can be steady for at least 10 months at 4℃ in a refrigerator.The resonance Rayleigh scattering(RRS) of CdTe NCs in the aqueous solution was investigated.The maximum scattering peak was located at about 554 nm.The interactions of CdTe NCs with amikacin sulfate(AS) and micronomicin sulfate(MS) were investigated respectively.The effects of AS and MS on fluorescence and RRS of CdTe NCs were analyzed.It was found that AS and MS quenched the photoluminescence of CdTe NCs and enhanced RRS of CdTe NCs.Under optimum conditions,there are linear relationships between quenching intensity(F0-F),intensity of RRS(I-I0) and concentration of AS and MS.The detection limits(3б) of AS and MS are respectively 3.4 ng·mL-1 and 2.6 ng·mL-1 by the fluorescence quenching method,and 15.2 ng·mL-1 and 14.0 ng·mL-1 by the RRS method.The methods have high sensitivity,thus CdTe NCs may be used as fluorescence probes and RRS probes for the detection of aminoglycoside antibiotics.

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

    Science.gov (United States)

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

  5. Partial characterization of an endemic strain of a methicillin- and aminoglycoside-resistant Staphylococcus aureus (MARSA) homogeneously resistant to beta-lactam antibiotics.

    Science.gov (United States)

    Jacob, J; Meers, P D

    1992-06-01

    Selected strains of methicillin- and aminoglycoside-resistant Staphylococcus aureus (MARSA) were subjected to a preliminary examination. They were representative of a larger group collected in a routine clinical microbiology laboratory over a period of 2 years. MARSA was endemic in the associated hospital. The characteristics investigated were antimicrobial resistance, the production of beta-lactamase, free and bound coagulase, protein A, DNA-ase, urease, lipase and pigment. The MARSA strains were generally indistinguishable, other than in their antimicrobial resistances. The resistance to methicillin was completely homogeneous. Except with imipenem, growth extended to the edge of discs containing methicillin and the other beta-lactam antibiotics tested when the strains were cultured at 37 degrees C on media without added salt. Homogeneous resistance may confer an epidemiological advantage on strains of this phenotype. PMID:1353087

  6. 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

    Decoding of genetic information occurs upon interaction of an mRNA codon-tRNA anticodon complex with the small subunit of the ribosome. The ribosomal decoding region is associated with highly conserved sequences near the 3' end of 16 S rRNA. The decoding process is perturbed by the aminoglycoside...... 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...... but are defective in forming functional ribosomes. Changes in the local conformation of the decoding region caused by these mutations were identified by chemical probing of isolated 30 S subunits. Ribosomes containing 16 S rRNA with mutations at positions 1408, 1407+1494, or 1495 had reduced affinity...

  7. 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

    2014-05-01

    Full Text Available  Several works demonstrated the importance of the study of natural products as an alternative source for new antimicrobial drugs or for modulators for these ones. In this point, the aim of this was to investigate the antibacterial activity and the possible interactions between the essential oil of Cymbopogon citratus alone and in association with aminoglycosides against standard and clinically isolated strains of multidrug-resistant bacteria such as S. aureus, E. coli and P. aeruginosa by microdilution method. The results indicated a synergism between the antibiotics and the essential oil with a subinhibitory concentration (MIC/8, reducing the minimal inhibitory concentration (MIC sixteen times against the multidrug-resistant strains of S. aureus 358, E. coli 27 and P. aeruginosa 143, but none modulatory activity was observed against P. aeruginosa 78 and P. aeruginosa 91 strains. By our results, can be concluded that the essential oil of Cymbopogon citratus can be an interesting source of natural products with antibacterial and/or modulatory antibiotic activitieAVALIAÇÃO DA ATIVIDADE ANTIBACTERIANA E MODULADORA DE AMINOGLICOSÍDEOS DO ÓLEO ESSENCIAL DE Cymbopogon citratus (DC. STAPFVários 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

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

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei T Chang; Meissner, Nicole; Oblad, John; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    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 de...

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

    OpenAIRE

    Shrestha, Sanjib K.; Cheng-Wei Tom Chang; Nicole eMeissner; John eOblad; Shrestha, Jaya P.; Sorensen, Kevin N.; Michelle M. Grilley; Jon Y Takemoto

    2014-01-01

    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 d...

  10. 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.

  11. Activation of PI3K signaling prevents aminoglycoside-induced hair cell death in the murine cochlea

    Directory of Open Access Journals (Sweden)

    Azadeh Jadali

    2016-06-01

    Full Text Available Loss of sensory hair cells of the inner ear due to aminoglycoside exposure is a major cause of hearing loss. Using an immortalized multipotent otic progenitor (iMOP cell line, specific signaling pathways that promote otic cell survival were identified. Of the signaling pathways identified, the PI3K pathway emerged as a strong candidate for promoting hair cell survival. In aging animals, components for active PI3K signaling are present but decrease in hair cells. In this study, we determined whether activated PI3K signaling in hair cells promotes survival. To activate PI3K signaling in hair cells, we used a small molecule inhibitor of PTEN or genetically ablated PTEN using a conditional knockout animal. Hair cell survival was challenged by addition of gentamicin to cochlear cultures. Hair cells with activated PI3K signaling were more resistant to aminoglycoside-induced hair cell death. These results indicate that increased PI3K signaling in hair cells promote survival and the PI3K signaling pathway is a target for preventing aminoglycoside-induced hearing loss.

  12. SYNTHESIS AND CYTOTOXIC ACTIVITY OF NEW 5H-INDOLO[2,3-B]QUINOLINE O-AMINOGLYCOSIDES.

    Science.gov (United States)

    Badowska-Rosłonek, Katarzyna; Ciesielska, Agnieszka; Switalska, Marta; Piskozub, Małgorzata; Peczyńska-Czoch, Wanda; Wietrzyk, Joanna; Kaczmarek, Łukasz

    2016-01-01

    Novel 5H-indolo[2,3-b]quinoline O-aminoglycosides were synthesized in order to check the hypothesis that the construction of hybrids composed of the active 5H-indolo[2,3-b]quinoline chromophore and daunosaminyl or acosaminyl moiety may result in the cytotoxic activity of the obtained derivatives that is much higher than the one of the parent DIMIQ (5,11-dimethyl-5H-indolo[2,3-b]quinoline) and 6H-indoloquinoline analogs. Actually, 5H-indolo[2,3-b]indoloquinoline O-aminoglycosides showed the anti-proliferative activity in vitro against human lung adenocarcinoma A549, breast cancer MCF-7, melanoma Hs294T, promyelocytic leukemia HL-60, uterine sarcoma MES-SA and colon cancer LoVo cell lines, which was 10 times higher than that of the 6H-analogs and comparable to the one of the referential DIMIQ. Unexpectedly, it appeared that except for HL-60/MX2 (P-gp-independent and topoisomerase II-dependent resistance), other MDR tumor cell lines (LoVo/DX. P-gp-dependent, MRP-, LRP-dependent multidrug resistance) and MES-SA/DX5 (P-gp-dependent resistance to doxorubicin) are also resistant to the 5H-indolo[2,3-b]indoloquinoline O-aminoglycosides tested. This is surprising because 6H-analogs, in general, 10 times less active against non-MDR tumor cell lines, as well as the DIMIQ itself, are able to overcome drug resistance in all MDR cell lines examined. The cytotoxicity of the tested compounds against tumor cell lines and against normal cells (mice fibroblasts BALB/3T3) was comparable. PMID:27476287

  13. Study of Pseudomonas Aeroginosa resistance to Penicillines, Cephalosporins and Aminoglycosides

    Directory of Open Access Journals (Sweden)

    Maleknezhad P

    1998-07-01

    Full Text Available Drug therapy and prophylaxy in infectious diseases, from hygienic and economical point of view, are very important. Infections caused by pseudomonas aeroginosa were particularly severe, with high mortality rates. In the recent years pseudomonas aeroginosa continued to cause the most severe, life-thereating infections in burned patients, in spite of the introduction of a wide variety of antibiotics advised specifically for their anti pseudomonal activity. The aim of this study, in which many cases of ps.aeroginosa infections are assessed is to identify the drug resistance of this bacteria to penicillines, cephalosporins and aminoglycosides by antibiotic sensitivity test (disk ager diffusion. Results as percent of resistance to each antibiotic were 89% to carbenicillin, 55% to piperacillin, 89% to mezlocillin, 89.5% to ticarcillin+clavulonic acid, 85% to ceftriaxone, 95% to tobramycin, 5% of all isolates were not sensitive to any antibiotics.

  14. CHEMICALLY FABRICATED SILVER NANOPARTICLES ENHANCES THE ACTIVITY OF ANTIBIOTICS AGAINST SELECTED HUMAN BACTERIAL PATHOGENS

    Directory of Open Access Journals (Sweden)

    S. Thangapandiyan and P. Prema*

    2012-05-01

    Full Text Available Due to the outbreak of infectious diseases caused by different pathogenic bacteria and the development of antibiotic resistance, the pharmaceutical companies and the researchers are now searching for new unconventional antibacterial agents. Nanotechnology represents a modern and innovative approach to develop new formulations based on metallic nanoparticles with antimicrobial properties. The potential bioactivity of chemically fabricated silver nanoparticles has been extensively studied. However, the antibacterial activity of silver nanoparticles individually or in combination with different antibiotics has not been demonstrated. In the present investigations, the effect of silver nanoparticles on the antibacterial activity of different antibiotics was evaluated against selected human bacterial pathogens such as Staphylococcus aureus, Streptococcus epidermis, Escherichia coli, Pseudomonas aeruginosa, and Bacillus cereus by disc diffusion method. In the presence of sub - inhibitory concentration of silver nanoparticles (100µL/disc, the antibacterial activities of all antibiotics are increased from 1 mm to 10 mm. The maximum fold increase was noticed for vancomycin against Pseudomonas aeruginosa (66.67%, Escherichia coli (62.50%, and Staphylococcus aureus (46% followed by rifampicin against Bacillus cereus (66.67% and kanamycin against Streptococcus epidermis (25%. These results signify that the silver nanoparticles showed potential antibacterial action of ß-lactams, glycopeptides, aminoglycosides, sulphonamides suggesting a possible utilization of silver nanocompounds in combination therapy against selected pathogens used in the experiment.

  15. Active controlled studies in antibiotic drug development.

    Science.gov (United States)

    Dane, Aaron

    2011-01-01

    The increasing concern of antibacterial resistance has been well documented, as has the relative lack of antibiotic development. This paradox is in part due to challenges with clinical development of antibiotics. Because of their rapid progression, untreated bacterial infections are associated with significant morbidity and mortality. As a consequence, placebo-controlled studies of new agents are unethical. Rather, pivotal development studies are mostly conducted using non-inferiority designs versus an active comparator. Further, infections because of comparator-resistant isolates must usually be excluded from the trial programme. Unfortunately, the placebo-controlled data classically used in support of non-inferiority designs are largely unavailable for antibiotics. The only available data are from the 1930s and 1940s and their use is associated with significant concerns regarding constancy and assay sensitivity. Extended public debate on this challenge has led to proposed solutions by some in which these concerns are addressed by using very conservative approaches to trial design, endpoints and non-inferiority margins, in some cases leading to potentially impractical studies. To compound this challenge, different Regulatory Authorities seem to be taking different approaches to these key issues. If harmonisation does not occur, antibiotic development will become increasingly challenging, with the risk of further decreases in the amount of antibiotic drug development. However with clarity on Regulatory requirements and an ability to feasibly conduct global development programmes, it should be possible to bring much needed additional antibiotics to patients.

  16. [Antibiotic activity of some fungi].

    Science.gov (United States)

    Savchuk, Ia I; Tsyganenko, K S; Zaĭchenko, O M

    2013-01-01

    Biological activity of pure extracts of cultural filtrates of Aspergillus niveus 2411, Myrothecium cinctum 910, Ulocladium consortiale 960, Penicillium sp. 10-51 concerning wide spectrum of test-organisms was investigated. It was shown that the extracts had high levels of antibacterial activity against Gram-positive microorganisms, especially against Bacillus genus. But their activity against Gram-negative bacteria was a bit lower. On the other hand, metabolites of M. cinctum 910 and Penicillium sp. 10-51 did show the activity concerning phytopathogenic bacteria. Extracts of fungi showed fungistatic activity against yeasts, but they were not so active concerning fungal test-cultures. Extracts of A. niveus 2411, Penicillium sp. 10-51 suppressed the growth of Phoma betae. The highest level of fungistatic activity was shown by metabolites of M. cinctum 910. They showed activity against Aspergillus genus strains and phytopathogenic isolates of Fusarium lactis, Rhizoctonia solani and Botrytis cinerea. PMID:24479314

  17. Multiple strategies to activate gold nanoparticles as antibiotics

    Science.gov (United States)

    Zhao, Yuyun; Jiang, Xingyu

    2013-08-01

    Widespread antibiotic resistance calls for new strategies. Nanotechnology provides a chance to overcome antibiotic resistance by multiple antibiotic mechanisms. This paper reviews the progress in activating gold nanoparticles with nonantibiotic or antibiotic molecules to combat bacterial resistance, analyzes the gap between experimental achievements and real clinical application, and suggests some potential directions in developing antibacterial nanodrugs.

  18. Pharmacokinetics of Aminoglycosides

    Institute of Scientific and Technical Information of China (English)

    Lokangu Lombo(Congo); HE Hua

    2004-01-01

    The Pharmacokinetics informations of aminoglycosides, their monograph and clinical Pharmacokinetics parameters are reported in this review. The Aminoglycosides are highly polarity and in reserve for serious infections caused by aerobic gram-negative bacteria and some gram-positive bacteria but their toxicity are major limitations in clinical use.

  19. Mitochondrial DNA Mutations Associated with Aminoglycoside Ototoxicity

    Institute of Scientific and Technical Information of China (English)

    GUAN Min-Xin

    2006-01-01

    The mitochondrial 12S rRNA has been shown to be the hot spot for mutations associated with both aminoglycoside-induced and non-syndromic hearing loss. Of all the mutations, the homoplasmic A1555G and C1494T mutations at a highly conserved decoding region in the 12S rRNA have been associated with aminoglycoside-induced and non-syndromic hearing loss in many families worldwide. The A1555G or C1494T mutation is expected to form novel 1494C-G1555 or 1494U-A1555 base-pair at the highly conserved A-site of 12S rRNA. These transitions make the secondary structure of this RNA more closely resemble the corresponding region of bacterial 16S rRNA. Thus, the new U - A or G-C pair in 12S rRNA created by the C1494T or A1555G transition facilitates the binding of aminoglycosides, thereby accounting for the fact that the exposure to aminoglycosides can induce or worsen hearing loss in individuals carrying these mutations. Furthermore, the growth defect and impairment of mitochondrial translation were observed in cell lines carrying the A1555G or C1494T mutation in the presence of high concentration of aminoglycosides. In addition, nuclear modifier genes and mitochondrial haplotypes modulate the phenotypic manifestation of the A1555G and C1494T mutations. These observations provide the direct genetic and biochemical evidences that the A1555G or C1494T mutation is a pathogenic mtDNA mutation associated with aminoglycoside-induced and nonsyndromic hearing loss. 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 antibiotic therapy, and eventually to decrease the incidence of deafness.

  20. Multiple antibiotic resistance in Stenotrophomonas maltophilia.

    OpenAIRE

    Alonso, A.; Martínez, J L

    1997-01-01

    A cryptic multidrug resistance (MDR) system in Stenotrophomonas maltophilia, the expression of which is selectable by tetracycline, is described. Tetracycline resistance was the consequence of active efflux of the antibiotic, and it was associated with resistance to quinolones and chloramphenicol, but not to aminoglycosides or beta-lactam antibiotics. MDR is linked to the expression of an outer membrane protein (OMP54) both in a model system and in multidrug-resistant clinical isolates.

  1. Mechanistic Study of the Synergistic Antibacterial Activity of Combined Silver Nanoparticles and Common Antibiotics.

    Science.gov (United States)

    Deng, Hua; McShan, Danielle; Zhang, Ying; Sinha, Sudarson S; Arslan, Zikri; Ray, Paresh C; Yu, Hongtao

    2016-08-16

    A combination of silver nanoparticles (AgNPs) and an antibiotic can synergistically inhibit bacterial growth, especially against the drug-resistant bacteria Salmonella typhimurium. However, the mechanism for the synergistic activity is not known. This study chooses four classes of antibiotics, β-lactam (ampicillin and penicillin), quinolone (enoxacin), aminoglycoside (kanamycin and neomycin), and polykeptide (tetracycline) to explore their synergistic mechanism when combined with AgNPs against the multidrug-resistant bacterium Salmonella typhimurium DT 104. Enoxacin, kanamycin, neomycin, and tetracycline show synergistic growth inhibition against the Salmonella bacteria when combined with AgNPs, while ampicillin and penicillin do not. UV-vis and Raman spectroscopy studies reveal that all these four synergistic antibiotics can form complexes with AgNPs, while ampicillin and penicillin do not. The presence of tetracycline enhances the binding of Ag to Salmonella by 21% and Ag(+) release by 26% in comparison to that without tetracycline, while the presence of penicillin does not enhance the binding of Ag or Ag(+) release. This means that AgNPs first form a complex with tetracycline. The tetracycline-AgNPs complex interacts more strongly with the Salmonella cells and causes more Ag(+) release, thus creating a temporal high concentration of Ag(+) near the bacteria cell wall that leads to growth inhibition of the bacteria. These findings agree with the recent findings that Ag(+) release from AgNPs is the agent causing toxicity. PMID:27390928

  2. Antibiotics

    Science.gov (United States)

    Antibiotics are powerful medicines that fight bacterial infections. Used properly, antibiotics can save lives. They either kill bacteria or ... natural defenses can usually take it from there. Antibiotics do not fight infections caused by viruses, such ...

  3. Endotoxemia-mediated inflammation potentiates aminoglycoside-induced ototoxicity

    Science.gov (United States)

    Koo, J.-W.; Quintanilla-Dieck, L.; Jiang, M.; Liu, J.; Urdang, Z. D.; Allensworth, J. J.; Cross, C. P.; Li, H.; Steyger, P. S.

    2015-01-01

    The ototoxic aminoglycoside antibiotics are essential to treat severe bacterial infections, particularly in neonatal intensive care units. Using a bacterial lipopolysaccharide (LPS) experimental model of sepsis, we tested whether LPS-mediated inflammation potentiates cochlear uptake of aminoglycosides and permanent hearing loss in mice. Using confocal microscopy and enzyme-linked immunosorbent assays, we found that low-dose LPS (endotoxemia) greatly increased cochlear concentrations of aminoglycosides and resulted in vasodilation of cochlear capillaries without inducing paracellular flux across the blood-labyrinth barrier (BLB), or elevating serum concentrations of the drug. Additionally, endotoxemia increased expression of both serum and cochlear inflammatory markers. These LPS-induced changes, classically mediated by Toll-like Receptor 4 (TLR4), were attenuated in TLR4-hyporesponsive mice. Multiday dosing with aminoglycosides during chronic endotoxemia induced greater hearing threshold shifts and sensory cell loss compared to mice without endotoxemia. Thus, endotoxemia-mediated inflammation enhanced aminoglycoside trafficking across the BLB, and potentiated aminoglycoside-induced ototoxicity. These data indicate that patients with severe infections are at greater risk of aminoglycoside-induced hearing loss than previously recognized. PMID:26223301

  4. A preliminary report on the susceptibility to aminoglycosides of Escherichia coli isolated from the community-acquired urinary tract infections in adults in south-east Poland

    Directory of Open Access Journals (Sweden)

    Fidecka-Skwarzynska Magdalena

    2015-03-01

    Full Text Available World-wide, urinary tract infections (UTIs are an important clinical problem. In such, the most frequently isolated uropathogen is Escherichia coli. In the treatment of uncomplicated UTIs, e.g. cystitis, the widely used antibiotics are nitrofurantoin, trimethoprim/sulfamethoxazole, fosfomycin trometamol or ciprofloxacin, while the treatment of pyelonephritis requires the usage of antibiotics with a broader spectrum of activity, such as cephalosporins of the 3rd and 4th generation, aminoglycosides or even carbapenems. The aim of this study was to assess the susceptibility to aminoglycosides (such as amikacin, gentamicin, netilmicin and tobramycin of E. coli isolated from UTIs in adult community patients living in Lubelszczyzna. We found that all of the 86 strains of E. coli encountered were susceptible to amikacin. Moreover, the prevalence of susceptibility to tobramycin, gentamicin or netilmicin among the tested strains was found to be 89,5%, 90,7% or 94,2%, respectively. The data obtained in the present study shows the high susceptibility to aminoglycosides of E. coli isolated from the community-acquired UTIS in adults. These data, together with that derived from current literature, indicate that aminoglycosides, when employed in combination therapy with other antibiotics, may still be very useful group of antibacterial agents in the treatment of UTI’s in Poland.

  5. Design, synthesis, and antibacterial activities of neomycin-lipid conjugates: polycationic lipids with potent gram-positive activity.

    Science.gov (United States)

    Bera, Smritilekha; Zhanel, George G; Schweizer, Frank

    2008-10-01

    Aminoglycoside antibiotics and cationic detergents constitute two classes of clinically important drugs and antiseptics. Their bacteriological and clinical efficacy, however, has decreased recently due to antibiotic resistance. We have synthesized aminoglycoside-lipid conjugates in which the aminoglycoside neomycin forms the cationic headgroup of a polycationic detergent. Our results show that neomycin-C16 and neomycin-C20 conjugates exhibit strong Gram-positive activity but reduced Gram-negative activity. The MIC of neomycin-C16 (C20) conjugates against methicillin-resistant Staphylococcus aureus (MRSA) is comparable to clinically used antiseptics.

  6. Synergistic antibacterial activity of Curcumin with antibiotics against Staphylococcus aureus.

    Science.gov (United States)

    Teow, Sin-Yeang; Ali, Syed Atif

    2015-11-01

    This study evaluated the synergistic antibacterial activity of Curcumin with 8 different antibiotic groups. Two reference, one clinical and ten environmental strains of Staphylococcus aureus (S. aureus) were tested. Disc diffusion assay with 25 μg/mL Curcumin demonstrated synergism in combination with a majority of tested antibiotics against S. aureus. However, checkerboard micro dilution assay only showed synergism, fractional inhibitory concentration index (FICI) indifferent interactions but no antagonism was observed. In time-kill curve, appreciable reduction of bacterial cells was also observed in combination therapy (Curcumin + antibiotics) compared to monotherapy (Curcumin or antibiotic(s) alone). The antibiotics with higher synergistic interaction with Curcumin are arranged in a decreasing order: Amikacin > Gentamicin > Ciprofloxacin.

  7. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

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

    2013-01-01

    Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we...... provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release......, which are thought to be a source of extracellular DNA at sites of infections, increases the tolerance of P. aeruginosa biofilms toward aminoglycosides. Although biofilm-associated aminoglycoside tolerance recently has been linked to extracellular DNA-mediated activation of the pmr genes, we demonstrate...

  8. Strategies to overcome the action of aminoglycoside-modifying enzymes for treating resistant bacterial infections

    OpenAIRE

    Labby, Kristin J.; Garneau-Tsodikova, Sylvie

    2013-01-01

    Shortly after the discovery of the first antibiotics, bacterial resistance began to emerge. Many mechanisms give rise to resistance; the most prevalent mechanism of resistance to the aminoglycoside (AG) family of antibiotics is the action of aminoglycoside-modifying enzymes (AMEs). Since the identification of these modifying enzymes, many efforts have been put forth to prevent their damaging alterations of AGs. These diverse strategies are discussed within this review, including: creating new...

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

    Directory of Open Access Journals (Sweden)

    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.

  10. DETERMINATION OF AMINOGLYCOSIDES IN FOOD BY FLUORESCENCE POLARIZATION IMMUNOASSAY

    Directory of Open Access Journals (Sweden)

    FARAFONOVA O.V.

    2015-01-01

    Full Text Available The methodic for quantitative determination of aminoglycoside antibiotics (gentamicin, kanamycin, streptomycin, amikacin, neomycin in food by polarization fluorescent immunoassay (FPIA is developed. The size and structure influence of a fluorescent molecule on a fluorescence polarization degree is analyzed. Affinity constants of antibodies to compounds and tracers were estimated, optimized working concentration of tracers and antibodies that provide the maximum value of analytical signal. Methods were tested in the antibiotics identification in milk, eggs and chicken.

  11. 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.

  12. Influence of antibiotic adsorption on biocidal activities of silver nanoparticles.

    Science.gov (United States)

    Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

    2016-04-01

    Excessive use of antibiotics has posed two major challenges in public healthcare. One of them is associated with the development of multi-drug resistance while the other one is linked to side effects. In the present investigation, the authors report an innovative approach to tackle the challenges of multi-drug resistance and acute toxicity of antibiotics by using antibiotics adsorbed metal nanoparticles. Monodisperse silver nanoparticles (SNPs) have been synthesised by two-step process. In the first step, SNPs were prepared by chemical reduction of AgNO3 with oleylamine and in the second step, oleylamine capped SNPs were phase-transferred into an aqueous medium by ligand exchange. Antibiotics - tetracycline and kanamycin were further adsorbed on the surface of SNPs. Antibacterial activities of SNPs and antibiotic adsorbed SNPs have been investigated on gram-positive (Staphylococcus aureus, Bacillus megaterium, Bacillus subtilis), and gram-negative (Proteus vulgaris, Shigella sonnei, Pseudomonas fluorescens) bacterial strains. Synergistic effect of SNPs on antibacterial activities of tetracycline and kanamycin has been observed. Biocidal activity of tetracycline is improved by 0-346% when adsorbed on SNPs; while for kanamycin, the improvement is 110-289%. This synergistic effect of SNPs on biocidal activities of antibiotics may be helpful in reducing their effective dosages.

  13. Influence of antibiotic adsorption on biocidal activities of silver nanoparticles.

    Science.gov (United States)

    Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

    2016-04-01

    Excessive use of antibiotics has posed two major challenges in public healthcare. One of them is associated with the development of multi-drug resistance while the other one is linked to side effects. In the present investigation, the authors report an innovative approach to tackle the challenges of multi-drug resistance and acute toxicity of antibiotics by using antibiotics adsorbed metal nanoparticles. Monodisperse silver nanoparticles (SNPs) have been synthesised by two-step process. In the first step, SNPs were prepared by chemical reduction of AgNO3 with oleylamine and in the second step, oleylamine capped SNPs were phase-transferred into an aqueous medium by ligand exchange. Antibiotics - tetracycline and kanamycin were further adsorbed on the surface of SNPs. Antibacterial activities of SNPs and antibiotic adsorbed SNPs have been investigated on gram-positive (Staphylococcus aureus, Bacillus megaterium, Bacillus subtilis), and gram-negative (Proteus vulgaris, Shigella sonnei, Pseudomonas fluorescens) bacterial strains. Synergistic effect of SNPs on antibacterial activities of tetracycline and kanamycin has been observed. Biocidal activity of tetracycline is improved by 0-346% when adsorbed on SNPs; while for kanamycin, the improvement is 110-289%. This synergistic effect of SNPs on biocidal activities of antibiotics may be helpful in reducing their effective dosages. PMID:27074856

  14. 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. PMID:23662150

  15. Cryptic antifungal compounds active by synergism with polyene antibiotics.

    Science.gov (United States)

    Kinoshita, Hiroshi; Yoshioka, Mariko; Ihara, Fumio; Nihira, Takuya

    2016-04-01

    The majority of antifungal compounds reported so far target the cell wall or cell membrane of fungi, suggesting that other types of antibiotics cannot exert their activity because they cannot penetrate into the cells. Therefore, if the permeability of the cell membrane could be enhanced, many antibiotics might be found to have antifungal activity. We here used the polyene antibiotic nystatin, which binds to ergosterol and forms pores at the cell membrane, to enhance the cellular permeability. In the presence of nystatin, many culture extracts from entomopathogenic fungi displayed antifungal activity. Among all the active extracts, two active components were purified and identified as helvolic acid and terramide A. Because the minimum inhibitory concentration of either compound was reduced four-fold in the presence of nystatin, it can be concluded that this screening method is useful for detecting novel antifungal activity.

  16. Ablation of mixed lineage kinase 3 (Mlk3) does not inhibit ototoxicity induced by acoustic trauma or aminoglycoside exposure.

    Science.gov (United States)

    Polesskaya, Oksana; Cunningham, Lisa L; Francis, Shimon P; Luebke, Anne E; Zhu, Xiaoxia; Collins, David; Vasilyeva, Olga N; Sahler, Julie; Desmet, Emily A; Gelbard, Harris A; Maggirwar, Sanjay B; Walton, Joseph P; Frisina, Robert D; Dewhurst, Stephen

    2010-12-01

    Jun N-terminal kinase (JNK) is activated in cochlear hair cells following acoustic trauma or exposure to aminoglycoside antibiotics. Blockade of JNK activation using mixed lineage kinase (MLK) inhibitors prevents hearing loss and hair cell death following these stresses. Since current pharmacologic inhibitors of MLKs block multiple members of this kinase family, we examined the contribution of the major neuronal family member (MLK3) to stress-induced ototoxicity, usingMlk3(-/-) mice. Immunohistochemical staining revealed that MLK3 is expressed in cochlear hair cells of C57/BL6 mice (but not in Mlk3(-/-) animals). After exposure to acoustic trauma there was no significant difference in DPOAE and ABR values betweenMlk3(-/-) and wild-type mice at 48 h following exposure or 2 weeks later. Susceptibility of hair cells to aminoglycoside toxicity was tested by exposing explanted utricles to gentamicin. Gentamicin-induced hair cell death was equivalent in utricles from wild-type and Mlk3(-/-) mice. Blockade of JNK activation with the pharmacologic inhibitor SP600125 attenuated cell death in utricles from both wild-type and Mlk3(-/-) mice. These data show that MLK3 ablation does not protect against hair cell death following acoustic trauma or exposure to aminoglycoside antibiotics, suggesting that MLK3 is not the major upstream regulator of JNK-mediated hair cell death following these stresses. Rather, other MLK family members such as MLK1, which is also expressed in cochlea, may have a previously unappreciated role in noise- and aminoglycoside-induced ototoxicity.

  17. A random sequential mechanism of aminoglycoside acetylation by Mycobacterium tuberculosis Eis protein.

    Directory of Open Access Journals (Sweden)

    Oleg V Tsodikov

    Full Text Available An important cause of bacterial resistance to aminoglycoside antibiotics is the enzymatic acetylation of their amino groups by acetyltransferases, which abolishes their binding to and inhibition of the bacterial ribosome. Enhanced intracellular survival (Eis protein from Mycobacterium tuberculosis (Mt is one of such acetyltransferases, whose upregulation was recently established as a cause of resistance to aminoglycosides in clinical cases of drug-resistant tuberculosis. The mechanism of aminoglycoside acetylation by MtEis is not completely understood. A systematic analysis of steady-state kinetics of acetylation of kanamycin A and neomycin B by Eis as a function of concentrations of these aminoglycosides and the acetyl donor, acetyl coenzyme A, reveals that MtEis employs a random-sequential bisubstrate mechanism of acetylation and yields the values of the kinetic parameters of this mechanism. The implications of these mechanistic properties for the design of inhibitors of Eis and other aminoglycoside acetyltransferases are discussed.

  18. In vitro read-through of phenylalanine hydroxylase (PAH) nonsense mutations using aminoglycosides: a potential therapy for phenylketonuria.

    Science.gov (United States)

    Ho, Gladys; Reichardt, Juergen; Christodoulou, John

    2013-11-01

    Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive inborn error of phenylalanine metabolism, predominantly caused by mutations in the phenylalanine hydroxylase (PAH) gene. Approximately 10% of patients carry a nonsense mutation, which results in an inactive or unstable truncated protein. In some genetic disorders, including cystic fibrosis and Duchenne muscular dystrophy, restoration of full-length protein has been achieved by aminoglycoside antibiotics, such as gentamicin and G-418 (Geneticin). More recently, nonsense read-through has been induced at greater rates using a non-aminoglycoside drug, PTC124 (Ataluren), which has the advantage of being non-toxic in contrast to the antibiotics. The efficacy of read-through induced by three compounds, aminoglycosides G418 and gentamicin, and PTC124 were evaluated for four nonsense mutations of PAH in an in vitro expression system in two mammalian cell lines (COS-7 and HEK293). The production of full-length PAH was investigated using western blotting and the functionality confirmed by enzyme activity. Gentamicin and G-418 induced read-through of nonsense PAH mutations in HEK293 cells. The read-through product partially restored enzymatic activity, which was significantly less than that of wild-type, but comparable to a missense mutation of PAH associated with less severe forms of PKU. Treatment with PTC124 up to 100 μM did not result in full-length PAH polypeptide. Nonsense read-through drugs are a potential form of treatment for PKU, although the high dosage of aminoglycosides used is not appropriate in a clinical setting. In vitro studies with new non-toxic read-through agents as well as in vivo studies would also be essential to determine the extent of read-through required to restore normal phenylalanine levels. PMID:23532445

  19. Natural products from the termite Nasutitermes corniger lowers aminoglycoside minimum inhibitory concentrations

    Directory of Open Access Journals (Sweden)

    Henrique D.M Coutinho

    2010-01-01

    Full Text Available Bacterial infectious agents present a risk to populations, as they are responsible for high morbidity and mortality. For combating these pathogens, our main line of defense is the use of antibiotics. However, indiscriminate use of these drugs develops resistant strains to these same drugs. The present study has tested the antibacterial and modifying antibiotic activity of natural products from Nasutitermes corniger (Termitidae (Motschulsky, a termite used in folk medicine in Northeast Brazil, by the microdilution and checkerboard methods, respectively. In this study, the aqueous extract from the nest of N. corniger (ANCE was prepared and tested with chlorpromazine (CPZ for its antimicrobial activity, using the microdilution method. CPZ and ANCE were used independently and also in combination with aminoglycosides, against a strain of Escherichia coli resistant to these antibiotics, to determine the participation of efflux systems in resistance mechanisms. The fractional inhibitory concentration (FIC index was calculated and evaluated for the occurrence of synergism, using the checkerboard method. The minimum inhibitory concentrations (MIC and minimum bactericidal concentrations (MBC values were ≥ 2048 µg/mL for both strains of E. coli assayed, indicating low antibacterial activity. However, synergism was observed with kanamycin when the decoction was used, but when chlorpromazine was used, synergism was observed with kanamycin, amikacin, and neomycin. This synergism with CPZ indicated the involvement of an efflux system in the resistance to these aminoglycosides. Therefore, it was suggested that the natural products from N. corniger could be used as a source of zoo-derived natural products with kanamycin-modifying activity, resulting in a new approach against bacterial resistance to antibiotics.

  20. High-Throughput Screening for Streptomyces Antibiotic Biosynthesis Activators

    OpenAIRE

    Li CHEN; Wang, Yemin; Guo, Hang; Xu, Min; Deng, Zixin; Tao, Meifeng

    2012-01-01

    A genomic cosmid library of Streptomyces clavuligerus was constructed and transferred efficiently by conjugation to Streptomyces lividans, and 12 distinct groups of overlapping cosmid clones that activated the silent actinorhodin biosynthesis gene cluster were identified. This generally applicable high-throughput screening procedure greatly facilitates the identification of antibiotic biosynthesis activators.

  1. Damaging Effects of Aminoglycoside Antibiotics on Cochlear Spiral Ganglion Neurons%氨基糖苷类抗生素对耳蜗螺旋神经节的损害作用

    Institute of Scientific and Technical Information of China (English)

    高可雷; 丁大连; 李鹏; 孙虹; Richard Salvi

    2015-01-01

    氨基糖苷类药物(AmAn)是一类经典的治疗革兰阴性菌感染的抗生素,但具有耳毒性和肾毒性。以往的研究认为AmAn的耳毒性仅仅针对内耳毛细胞并可引起继发的延迟性螺旋神经节细胞(SGNs)死亡。但是随着关于AmAn耳毒性和对耳蜗其他细胞的研究进展,人们逐渐意识到耳蜗内支持细胞的损害也是引起SGNs延迟死亡的重要原因之一。我们发现,不同的AmAn对内耳的损害方式不同,以硫酸链霉素为代表的少数AmAn可以不受血-迷路屏障阻碍直接进入内耳并首先损害内耳的周边神经元;而以往认为只能间接损害SGNs的其他那些难以跨越血-迷路屏障的AmAn,比如卡那霉素,对出生后三天大鼠处于发育阶段的SGNs也具有直接的损害作用。因此我们提出一个根据不同内耳损害方式来区分AmAn的分类建议,并希望本文介绍的新内容能够为更深入理解不同种类AmAn的不同耳毒性机制以及听觉系统各个重要组织成分之间的相互作用关系提供新的参考信息。%Aminoglycoside antibiotics (AmAn) are widely used for gram negative bacterial infections while they are al⁃so notorious for their ototoxicity and nephrotoxicity. Conventional view is that the ototoxic effects of AmAn can only damage sensory hair cells in the inner ear, and can cause delayed spiral ganglion neurons (SGNs) degeneration as a result of the loss of sensory hair cells. But with deepening of research, people have come to realize that supporting cell damage is also one of the important reasons for the delayed SGNs death. Meanwhile, it has been found that different AmAns may exert their ototoxic ef⁃fects through different approaches to different target cells via different pathways. Streptomycin sulfate, which represents a mi⁃nor category of AmAn, passes easily through the blood-labyrinth barrier and can directly damage peripheral neurons in the in⁃ner ear. AmAns that

  2. Fe-S cluster biosynthesis controls uptake of aminoglycosides in a ROS-less death pathway.

    Science.gov (United States)

    Ezraty, Benjamin; Vergnes, Alexandra; Banzhaf, Manuel; Duverger, Yohann; Huguenot, Allison; Brochado, Ana Rita; Su, Shu-Yi; Espinosa, Leon; Loiseau, Laurent; Py, Béatrice; Typas, Athanasios; Barras, Frédéric

    2013-06-28

    All bactericidal antibiotics were recently proposed to kill by inducing reactive oxygen species (ROS) production, causing destabilization of iron-sulfur (Fe-S) clusters and generating Fenton chemistry. We find that the ROS response is dispensable upon treatment with bactericidal antibiotics. Furthermore, we demonstrate that Fe-S clusters are required for killing only by aminoglycosides. In contrast to cells, using the major Fe-S cluster biosynthesis machinery, ISC, cells using the alternative machinery, SUF, cannot efficiently mature respiratory complexes I and II, resulting in impendence of the proton motive force (PMF), which is required for bactericidal aminoglycoside uptake. Similarly, during iron limitation, cells become intrinsically resistant to aminoglycosides by switching from ISC to SUF and down-regulating both respiratory complexes. We conclude that Fe-S proteins promote aminoglycoside killing by enabling their uptake.

  3. 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....... Here, we show that aminoglycosides cause cytosolic protein misfolding and that chaperonin GroEL/GroES overexpression counters this defect. During aminoglycoside exposure to exponential cultures, chaperonin overexpression protected the bacterial membrane potential, rescued cell growth, and facilitated...... bacteria cope during early exposure to these drugs....

  4. 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.

  5. 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.

  6. Metabolic Activity Interferometer: A Powerful Tool for Testing Antibiotics

    Directory of Open Access Journals (Sweden)

    Rachel R. P. Machado

    2012-01-01

    Full Text Available It is demonstrated that the efficiency of antibiotics can be tested using an interferometric method. Two antibiotics were used as models to show that an interferometric method to monitor the metabolic activity of slowly growing bacteria can be a safer method to judge antimicrobial properties of substances than conventional methods. The susceptibility of Mycobacterium bovis to hexane extract of Pterodon emarginatus and to the well-known antibiotic rifampicin was tested with the interferometric method and with the conventional microplate method. The microplate method revealed a potential activity of hexane extract against M. bovis. However, the interferometric method showed that the action of this substance is rather limited. Also in the case of rifampicin, the interferometric method was able to detect resistant bacteria.

  7. Once Daily Dosing of Aminoglycosides in Pediatric Cystic Fibrosis Patients: A Review of the Literature

    OpenAIRE

    Wassil, Sarah K.; Fox, Kristie M.; White, James W.

    2008-01-01

    Patients with cystic fibrosis receive many courses of antibiotic therapy throughout their lifetime. Dosing aminoglycosides once daily has become common practice in many of these individuals. Due to ease of home administration, decreased nursing time, and improved quality of life, this regimen is being increasingly explored in the cystic fibrosis population. Because patients with cystic fibrosis have increased aminoglycoside clearance, once daily dosing may result in a prolonged time during th...

  8. Assessment on the adverse effects of Aminoglycosides and Flouroquinolone on sperm parameters and male reproductive tissue: A systematic review

    OpenAIRE

    Arash Khaki

    2015-01-01

    Background: Antibiotic therapies used in treatment of many diseases have adverse effects on fertility. This review analyzes previous comparative studies that surveyed the effects of two common groups of antibiotics on male fertility. Objective: To evaluate histo-pathological effects of fluoroquinolones and aminoglycosides on sperm parameters and male reproductive tissue. Materials and Methods: Articles about the effects of aminoglycosides and fluoroquinolones on male infertility, sperm parame...

  9. Mycobacteriophage putative GTPase-activating protein can potentiate antibiotics.

    Science.gov (United States)

    Yan, Shuangquan; Xu, Mengmeng; Duan, Xiangke; Yu, Zhaoxiao; Li, Qiming; Xie, Longxiang; Fan, Xiangyu; Xie, Jianping

    2016-09-01

    The soaring incidences of infection by antimicrobial resistant (AR) pathogens and shortage of effective antibiotics with new mechanisms of action have renewed interest in phage therapy. This scenario is exemplified by resistant tuberculosis (TB), caused by resistant Mycobacterium tuberculosis. Mycobacteriophage SWU1 A321_gp67 encodes a putative GTPase-activating protein. Mycobacterium smegmatis with gp67 overexpression showed changed colony formation and biofilm morphology and supports the efficacy of streptomycin and capreomycin against Mycobacterium. gp67 down-regulated the transcription of genes involved in cell wall and biofilm development. To our knowledge, this is the first report to show that phage protein in addition to lysin or recombination components can synergize with existing antibiotics. Phage components might represent a promising new clue for better antibiotic potentiators. PMID:27345061

  10. In Vitro Antimalarial Activity of Novel Semisynthetic Nocathiacin I Antibiotics

    OpenAIRE

    Sharma, Indu; Sullivan, Margery; McCutchan, Thomas F.

    2015-01-01

    Presently, the arsenal of antimalarial drugs is limited and needs to be replenished. We evaluated the potential antimalarial activity of two water-soluble derivatives of nocathiacin (BMS461996 and BMS411886) against the asexual blood stages of Plasmodium falciparum. Nocathiacins are a thiazolyl peptide group of antibiotics, are structurally related to thiostrepton, have potent activity against a wide spectrum of multidrug-resistant Gram-positive bacteria, and inhibit protein synthesis. The in...

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics

    DEFF Research Database (Denmark)

    Rathe, Mathias; Lise, Kristensen,; Ellermann-Eriksen, Svend;

    Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics......Vancomycin-resistant enterococci: validation of susceptibility testing and in vitro activity of novel antibiotics...

  13. 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.

  14. High level aminoglycoside resistance and distribution of aminoglycoside resistant genes among clinical isolates of Enterococcus species in Chennai, India.

    Science.gov (United States)

    Padmasini, Elango; Padmaraj, R; Ramesh, S Srivani

    2014-01-01

    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.

  15. Antibiofilm Activity of Manuka Honey in Combination with Antibiotics

    OpenAIRE

    Campeau, Michelle E. M.; Robin Patel

    2014-01-01

    We assessed the in vitro activity of Manuka honey against biofilm bacteria in combination with antibiotics and visualized the effect of Manuka honey on bacterial biofilms using scanning electron microscopy. The fractional biofilm eradication concentration (∑FBEC ) index for vancomycin plus Manuka honey against S. aureus IDRL-4284 biofilms was 0.34, indicating a synergistic interaction. The ∑FBEC  index for gentamicin plus Manuka honey against P. aeruginosa PAO1 biofilms was 0.78–0.82, indicat...

  16. Nanoliposomes containing Eucalyptus citriodora as antibiotic with specific antimicrobial activity.

    Science.gov (United States)

    Lin, Lin; Cui, Haiying; Zhou, Hui; Zhang, Xuejing; Bortolini, Christian; Chen, Menglin; Liu, Lei; Dong, Mingdong

    2015-02-14

    Bacterial infections are a serious issue for public health and represent one of the major challenges of modern medicine. In this work, a selective antimicrobial strategy based on triggering of pore-forming toxin, which is secreted by infective bacteria, was designed to fight Staphylococcus aureus. The antimicrobial activity is realized by employing Eucalyptus citriodora oil as antibiotic which in this study is encapsulated in nanoliposomes. PMID:25573466

  17. 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......-term tolerance, respectively, to this drug class. Here, we show that chaperonin GroEL/GroES over-expression accelerates acquisition of streptomycin resistance and reduces susceptibility to several other antibiotics following sub-lethal streptomycin antibiotic exposure. Chaperonin buffering could provide a novel...

  18. In vitro and in vivo activities of antibiotic PM181104

    Digital Repository Service at National Institute of Oceanography (India)

    Mahajan, G.B.; Thomas, B.; Parab, R.; Patel, Z.E.; Kuldharan, S.; Yemparala, V.; Mishra, P.D.; Ranadive, P.; DeSouza, L.; Pari, K.; Sivaramkrishnan, H.

    at a dose of 5mg/kg. Anti-infective activity of PM181104 for organ or tissue-specific infection was evaluated in two mouse models – skin abscess model (data not presented) and lung infection model. The lung bacterial titer at 48 hours post... control and two standard antibiotics – linezolid given i.p. at 25mg/kg dose and vancomycin given at 110mg/kg iv dose. Arrows indicate the dosing times. FIG 7 shows in vivo antibacterial activity of PM181104 against MRSA in murine skin abscess model...

  19. Aminoglycoside-mediated relaxation of the ductus arteriosus in sepsis-associated PDA.

    Science.gov (United States)

    Vucovich, Megan M; Cotton, Robert B; Shelton, Elaine L; Goettel, Jeremy A; Ehinger, Noah J; Poole, Stanley D; Brown, Naoko; Wynn, James L; Paria, Bibhash C; Slaughter, James C; Clark, Reese H; Rojas, Mario A; Reese, Jeff

    2014-09-01

    Sepsis is strongly associated with patency of the ductus arteriosus (PDA) in critically ill newborns. Inflammation and the aminoglycoside antibiotics used to treat neonatal sepsis cause smooth muscle relaxation, but their contribution to PDA is unknown. We examined whether: 1) lipopolysaccharide (LPS) or inflammatory cytokines cause relaxation of the ex vivo mouse DA; 2) the aminoglycosides gentamicin, tobramycin, or amikacin causes DA relaxation; and 3) newborn infants treated with aminoglycosides have an increased risk of symptomatic PDA (sPDA). Changes in fetal mouse DA tone were measured by pressure myography in response to LPS, TNF-α, IFN-γ, macrophage-inflammatory protein 2, IL-15, IL-13, CXC chemokine ligand 12, or three aminoglycosides. A clinical database of inborn patients of all gestations was analyzed for association between sPDA and aminoglycoside treatment. Contrary to expectation, neither LPS nor any of the inflammatory mediators caused DA relaxation. However, each of the aminoglycosides caused concentration-dependent vasodilation in term and preterm mouse DAs. Pretreatment with indomethacin and N-(G)-nitro-L-arginine methyl ester did not prevent gentamicin-induced DA relaxation. Gentamicin-exposed DAs developed less oxygen-induced constriction than unexposed DAs. Among 488,349 infants who met the study criteria, 40,472 (8.3%) had sPDA. Confounder-adjusted odds of sPDA were higher in gentamicin-exposed infants, 32 wk. Together, these findings suggest that factors other than inflammation contribute to PDA. Aminoglycoside-induced vasorelaxation and inhibition of oxygen-induced DA constriction support the paradox that antibiotic treatment of sepsis may contribute to DA relaxation. This association was also found in newborn infants, suggesting that antibiotic selection may be an important consideration in efforts to reduce sepsis-associated PDA. PMID:24993047

  20. Chemoprophylactic efficacy against experimental endocarditis caused by beta-lactamase-producing, aminoglycoside-resistant enterococci is associated with prolonged serum inhibitory activity.

    OpenAIRE

    Bayer, A S; Tu, J

    1990-01-01

    We studied the prevention of experimental aortic endocarditis caused by a beta-lactamase-producing, aminoglycoside-resistant strain of Enterococcus faecalis (HH22) in 146 catheterized rabbits. Both vancomycin and ampicillin-sulbactam readily killed this resistant enterococcus strain in vitro. At a challenge inoculum of approximately 10(9) CFU, vancomycin (40 mg/kg intravenously [i.v.]), ampicillin (40 mg/kg i.v.), or a combination of ampicillin plus a beta-lactamase inhibitor, sulbactam (20 m...

  1. 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.

  2. Structural Analysis of a Putative Aminoglycoside N-Acetyltransferase from Bacillus anthracis

    Energy Technology Data Exchange (ETDEWEB)

    Klimecka, Maria M.; Chruszcz, Maksymilian; Font, Jose; Skarina, Tatiana; Shumilin, Igor; Onopryienko, Olena; Porebski, Przemyslaw J.; Cymborowski, Marcin; Zimmerman, Matthew D.; Hasseman, Jeremy; Glomski, Ian J.; Lebioda, Lukasz; Savchenko, Alexei; Edwards, Aled; Minor, Wladek (SC); (Toronto); (UV)

    2012-02-15

    For the last decade, worldwide efforts for the treatment of anthrax infection have focused on developing effective vaccines. Patients that are already infected are still treated traditionally using different types of standard antimicrobial agents. The most popular are antibiotics such as tetracyclines and fluoroquinolones. While aminoglycosides appear to be less effective antimicrobial agents than other antibiotics, synthetic aminoglycosides have been shown to act as potent inhibitors of anthrax lethal factor and may have potential application as antitoxins. Here, we present a structural analysis of the BA2930 protein, a putative aminoglycoside acetyltransferase, which may be a component of the bacterium's aminoglycoside resistance mechanism. The determined structures revealed details of a fold characteristic only for one other protein structure in the Protein Data Bank, namely, YokD from Bacillus subtilis. Both BA2930 and YokD are members of the Antibiotic-NAT superfamily (PF02522). Sequential and structural analyses showed that residues conserved throughout the Antibiotic-NAT superfamily are responsible for the binding of the cofactor acetyl coenzyme A. The interaction of BA2930 with cofactors was characterized by both crystallographic and binding studies.

  3. Natural Bizbenzoquinoline Derivatives Protect Zebrafish Lateral Line Sensory Hair Cells from Aminoglycoside Toxicity.

    Science.gov (United States)

    Kruger, Matthew; Boney, Robert; Ordoobadi, Alexander J; Sommers, Thomas F; Trapani, Josef G; Coffin, Allison B

    2016-01-01

    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. PMID:27065807

  4. Microcalorimetric Study on the Antibiotic Activity of Clarithromycin and Erythromycin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    By using LKB-2277 Bioactivity Monitoring System, the heat effect changes in the process of inhibitory action of clarithromycin and erythromycin on Escherichia coli at 37℃ were determined. Quantitative analysis showed that relationship between antibiotic concentration c and rate constant k of Escherichia coli growth, and half inhibitory ratio concentration ICs0: clarithromyein: k= 0. 030 03- 1. 1736 × 10-3c, 8. 45 mg ?L-1 ;erythromycin:k=0. 031 08-8. 4657?10-4c, 14. 45 mg ?L-1. As a result of the microcalorimetry experiments, it not only indicated that antibacterial activity of clarithromycin was stronger than that of ery0thromycin, but also reported the changeable features of thermodynamics of the bacterial cell in biological,biochemical and metabolic process under different drug action.

  5. Urinary antibiotic activity in paediatric patients attending an outpatient department in north-western Cambodia

    OpenAIRE

    Emary, KR; Carter, MJ; Pol, S; Sona, S; V. Kumar; Day, NP; Parry, CM; Moore, CE

    2014-01-01

    Objective Antibiotic resistance is a prominent public and global health concern. We investigated antibiotic use in children by determining the proportion of unselected children with antibacterial activity in their urine attending a paediatric outpatient department in Siem Reap, Cambodia. Methods Caregiver reports of medication history and presence of possible infection symptoms were collected in addition to urine samples. Urine antibiotic activity was estimated by exposing bacteria to urine s...

  6. Mitomycin antibiotic reductive potential and related pharmacological activities.

    Science.gov (United States)

    Pan, S S; Gonzalez, H

    1990-06-01

    Relationships of reductive potential, kinetics of enzymatic reduction, augmented oxygen consumption, and cytotoxicity were determined for seven clinically relevant mitomycin antibiotics. Potentials for one-electron reduction were obtained by cyclic voltammetry analysis in dimethyl sulfoxide with 0.1 M tetraethyl-ammonium perchlorate. These potentials were -0.55 V for N7-acetylmitomycin C, -0.61 V for mitomycin A, -0.75 V for N7-(p-hydroxyphenyl)mitomycin C, -0.79 V for N7-(dimethylamino-methylene)mitomycin C, -0.81 V for N7-(2-(4-nitrophenyldithio)-ethyl)-mitomycin C, -0.81 V for mitomycin C, and -0.89 V for porfiromycin. All seven antibiotics were reduced by xanthine oxidase and NADPH-cytochrome P450 reductase, but the rate of reduction varied for each antibiotic and each enzyme. The less negative the reductive potential of an antibiotic, the more easily that antibiotic was reduced enzymatically. These seven mitomycin antibiotics also augmented oxygen consumption by rat liver microsomes. As with their reduction by xanthine oxidase and NADPH-cytochrome P450 reductase, the less negative the reductive potential of an antibiotic, the more it augmented oxygen consumption. Cytotoxicity of each antibiotic was assessed by defining the IC50 against HCT 116 human colon carcinoma cells. A relationship between the reductive potential of these antibiotics and their cytotoxicity against HCT 116 cells was also observed. PMID:2113607

  7. 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.

  8. Isolated deafness following recovery from neurologic injury and adult respiratory distress syndrome. A sequela of intercurrent aminoglycoside and diuretic use.

    Science.gov (United States)

    Lynn, A M; Redding, G J; Morray, J P; Tyler, D C

    1985-05-01

    We report two children who survived neurologic injury (near-drowning and Reye's syndrome) and adult respiratory distress syndrome and who required prolonged ventilatory support. Follow-up examination in both children showed steady neurologic recovery, but five months following discharge from their acute illness, profound hearing loss was diagnosed in both children. A review of the literature is reported and the hypothesis that combined aminoglycoside antibiotic and loop diuretic therapy caused the hearing loss is presented. Recommendation is made for audiologic assessment within six months of recovery from critical illness of pediatric patients in whom therapy has included loop diuretic and aminoglycoside 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.

  10. Once-daily aminoglycoside therapy: potential ototoxicity.

    OpenAIRE

    Kirkpatrick, C. M.; Duffull, S. B.; Begg, E J

    1996-01-01

    Current data indicate that once-daily aminoglycoside therapy is as efficacious as traditional multiple daily dosing and equally or less toxic. Our experience with once-daily gentamicin, 6 mg/kg of body weight led to a 10% (3 of 33 patients) occurrence of documented ototoxicity after prolonged aminoglycoside exposure.

  11. [Is it possible to reduce the incidence of aminoglycoside-induced nephrotoxicity?].

    Science.gov (United States)

    Fillastre, J P

    1999-01-01

    The incidence of nephrotoxicity due to aminoglycosides should be sharply reduced. The indications for prescribing these antibiotics should be limited to infectious disorders induced by aerobic Gram-negative bacteria and by some Gram-positive bacteria requiring treatment in specialized hospital units using an association of aminoglycosides and another antibiotic. Daily doses should not exceed those indicated by the manufacturer, and the length of treatment should be as short as possible, with a relay to other antibiotics that are not or are less nephrotoxic. The possibilities for reducing the incidence of nephrotoxicity are few. It is not possible to prevent the antibiotic from entering the renal tubular cell or from producing deleterious effects therein. However, by using short-term intravenous infusion as the administration route, prolonged contact between the antibiotic and its receptors on the brush borders of the proximal tubular cells can be avoided, particularly since the process of cellular absorption is saturable. Essentially, doses should be adapted according to the age and the glomerular filtration of the patient, since renal function usually decreases with age. Volemic and hydroelectrolytic disorders favour nephrotoxicity and should be corrected. Associations with other nephrotoxic drugs should either be avoided or used with increased caution. The same is true in special situations such as endotoxaemia, severe renal parenchymatous infections and cholestasis. In any case, given the well-known insidious onset of nephropathy, aminoglycoside treatment always requires laboratory follow-up consisting of repeated testing of creatinemia during the two weeks of treatment. PMID:10465001

  12. Deoxyribonucleoside kinases activate nucleoside antibiotics in severely pathogenic bacteria

    DEFF Research Database (Denmark)

    Sandrini, Michael; Shannon, O.; Clausen, A.R.;

    2007-01-01

    Common bacterial pathogens are becoming progressively more resistant to traditional antibiotics, representing a major public-health crisis. Therefore, there is a need for a variety of antibiotics with alternative modes of action. In our study, several nucleoside analogs were tested against...... alternative for combating pathogenic bacteria....

  13. In vitro antimalarial activity of novel semisynthetic nocathiacin I antibiotics.

    Science.gov (United States)

    Sharma, Indu; Sullivan, Margery; McCutchan, Thomas F

    2015-01-01

    Presently, the arsenal of antimalarial drugs is limited and needs to be replenished. We evaluated the potential antimalarial activity of two water-soluble derivatives of nocathiacin (BMS461996 and BMS411886) against the asexual blood stages of Plasmodium falciparum. Nocathiacins are a thiazolyl peptide group of antibiotics, are structurally related to thiostrepton, have potent activity against a wide spectrum of multidrug-resistant Gram-positive bacteria, and inhibit protein synthesis. The in vitro growth inhibition assay was done using three laboratory strains of P. falciparum displaying various levels of chloroquine (CQ) susceptibility. Our results indicate that BMS461996 has potent antimalarial activity and inhibits parasite growth with mean 50% inhibitory concentrations (IC50s) of 51.55 nM for P. falciparum 3D7 (CQ susceptible), 85.67 nM for P. falciparum Dd2 (accelerated resistance to multiple drugs [ARMD]), and 99.44 nM for P. falciparum K1 (resistant to CQ, pyrimethamine, and sulfadoxine). Similar results at approximately 7-fold higher IC50s were obtained with BMS411886 than with BMS461996. We also tested the effect of BMS491996 on gametocytes; our results show that at a 20-fold excess of the mean IC50, gametocytes were deformed with a pyknotic nucleus and growth of stage I to IV gametocytes was arrested. This preliminary study shows a significant potential for nocathiacin analogues to be developed as antimalarial drug candidates and to warrant further investigation. PMID:25779576

  14. Phytochemical Prospection and Modulation of Antibiotic Activity In Vitro by Lippia origanoides H.B.K. in Methicillin Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Humberto Medeiros Barreto

    2014-01-01

    Full Text Available The Lippia origanoides H.B.K. ethanol extract (LOEE and hexane (LOHEX, dichloromethane (LODCM, and ethyl acetate (LOEA fractions were tested for their antimicrobial activity alone or in combination with antibiotics against a methicillin resistant Staphylococcus aureus (MRSA strain. The natural products did not show antimicrobial activity against multidrug resistant strain at the clinically significant concentrations tested. However, a modulatory effect in the antibacterial activity of the neomycin and amikacin was verified when LOEE, LOHEX and LODCM were added to the growth medium at subinhibitory concentrations. A similar modulation was found when the natural products were changed for chlorpromazine, an inhibitor of bacterial efflux pumps, suggesting the involvement of resistance mediated by efflux system in the MRSA tested. The fractions LOHEX and LODCM showed a modulatory activity bigger than their majority compounds (carvacrol, thymol, and naringenin, indicating that this activity is not due to their majority compounds only, but it is probably due to a synergism between their chemical components. These results indicate that L. origanoides H.B.K. can be a source of phytochemicals able to modify the phenotype of resistance to aminoglycosides in MRSA.

  15. 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.

  16. 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.

  17. Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in Mycobacterium smegmatis.

    Science.gov (United States)

    Bartek, I L; Reichlen, M J; Honaker, R W; Leistikow, R L; Clambey, E T; Scobey, M S; Hinds, A B; Born, S E; Covey, C R; Schurr, M J; Lenaerts, A J; Voskuil, M I

    2016-01-01

    Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject. Herein, we demonstrate that the bactericidal activity of diverse antibiotics against Mycobacterium smegmatis and four evolutionarily divergent bacterial pathogens was blocked by conditions that worked to maintain intracellular pH homeostasis. Single-cell pH analysis demonstrated that antibiotics increased the cytosolic pH of M. smegmatis, while conditions that promoted proton entry into the cytosol prevented intracellular alkalization and antibiotic killing. These findings led to a hypothesis that posits antibiotic lethality occurs when antibiotics obstruct ATP-consuming biosynthetic processes while metabolically driven proton efflux is sustained despite the loss of proton influx via ATP synthase. Consequently, without a concomitant reduction in respiratory proton efflux, cell death occurs due to intracellular alkalization. Our findings indicate the effects of antibiotics on pH homeostasis should be considered a potential mechanism contributing to antibiotic lethality. IMPORTANCE Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our findings

  18. Identification of aminoglycoside resistance genes by Triplex PCR in Enterococcus spp. isolated from ICUs.

    Science.gov (United States)

    Mirnejad, Reza; Sajjadi, Nikta; Masoumi Zavaryani, Sara; Piranfar, Vahhab; Hajihosseini, Maryam; Roshanfekr, Maliheh

    2016-09-01

    Early detection of antibiotic-resistant enterococci is an important part of patient treatment. Therefore, the aim of the present study was to evaluate the resistance patterns and simultaneously identify and characterise the resistance genes in Enterococcus spp. using a triplex polymerase chain reaction (PCR) method. In all, 150 consecutive Enterococcus spp were collected from several hospitals in Tehran (Iran) from January to December 2015. The Enterococcus species were identified by standard phenotypic/biochemical tests and PCR. The antimicrobial resistance patterns were determined using a disk diffusion method. The triplex PCR method was designed to identify gentamicin and other aminoglycoside resistance genes. Among the 150 Enterococcus specimens, 87 cases (58%) were Enterococcus faecalis, and 63 cases (42%) were Enterococcus faecium. The highest frequency of resistance was observed for tetracycline while the lowest was found for vancomycin. Among the identified samples, 56.9% contained the aac(6')-Ie-aph(2'')-Ia gene, 22.2% contained the aph(3')-IIIa gene, and 38.8% contained the ant(4')-?a gene. Eight percent of the isolates contained the three aminoglycoside resistance genes. Data analysis showed that there was a significant correlation between the phenotypic gentamicin resistance and the presence of the aminoglycoside resistance genes (18.9%, p Enterococcus strains had increased aminoglycoside resistance. The direct correlation between resistance genes, such as the aminoglycoside resistance factor, and phenotypic resistance was not significant (p > 0.05).

  19. Antibiofilm Activity of Manuka Honey in Combination with Antibiotics

    Directory of Open Access Journals (Sweden)

    Michelle E. M. Campeau

    2014-01-01

    Full Text Available We assessed the in vitro activity of Manuka honey against biofilm bacteria in combination with antibiotics and visualized the effect of Manuka honey on bacterial biofilms using scanning electron microscopy. The fractional biofilm eradication concentration (∑FBEC  index for vancomycin plus Manuka honey against S. aureus IDRL-4284 biofilms was 0.34, indicating a synergistic interaction. The ∑FBEC  index for gentamicin plus Manuka honey against P. aeruginosa PAO1 biofilms was 0.78–0.82, indicating an additive interaction. Scanning electron microscopy of S. aureus IDRL-4284 and P. aeruginosa PAO1 biofilms exposed to Manuka honey and artificial honey containing the same sugar composition as Manuka honey showed that the former had more pronounced effects than the latter on both S. aureus and P. aeruginosa biofilms. Visualized effects included distorted cell morphologies for both bacteria and a decrease in P. aeruginosa extracellular matrix. In conclusion, Manuka honey has a synergistic interaction with vancomycin against S. aureus biofilms and an additive interaction with gentamicin against P. aeruginosa biofilms.

  20. Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in Mycobacterium smegmatis

    Science.gov (United States)

    Bartek, I. L.; Reichlen, M. J.; Honaker, R. W.; Leistikow, R. L.; Clambey, E. T.; Scobey, M. S.; Hinds, A. B.; Born, S. E.; Covey, C. R.; Schurr, M. J.; Lenaerts, A. J.

    2016-01-01

    ABSTRACT Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject. Herein, we demonstrate that the bactericidal activity of diverse antibiotics against Mycobacterium smegmatis and four evolutionarily divergent bacterial pathogens was blocked by conditions that worked to maintain intracellular pH homeostasis. Single-cell pH analysis demonstrated that antibiotics increased the cytosolic pH of M. smegmatis, while conditions that promoted proton entry into the cytosol prevented intracellular alkalization and antibiotic killing. These findings led to a hypothesis that posits antibiotic lethality occurs when antibiotics obstruct ATP-consuming biosynthetic processes while metabolically driven proton efflux is sustained despite the loss of proton influx via ATP synthase. Consequently, without a concomitant reduction in respiratory proton efflux, cell death occurs due to intracellular alkalization. Our findings indicate the effects of antibiotics on pH homeostasis should be considered a potential mechanism contributing to antibiotic lethality. IMPORTANCE Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our

  1. Hydramycin, a new antitumor antibiotic. Taxonomy, isolation, physico-chemical properties, structure and biological activity.

    Science.gov (United States)

    Hanada, M; Kaneta, K; Nishiyama, Y; Hoshino, Y; Konishi, M; Oki, T

    1991-08-01

    A new antitumor antibiotic hydramycin was isolated from the fermentation broth of Streptomyces violaceus P950-4 (ATCC 53807). It showed potent antibacterial and cytotoxic activity and increased the survival time of mice inoculated with P388 leukemia. A new structure related to the pluramycin group antibiotics was assigned by its spectroscopic experiments. PMID:1833366

  2. Mildiomycin: a nucleoside antibiotic that inhibits protein synthesis.

    Science.gov (United States)

    Feduchi, E; Cosín, M; Carrasco, L

    1985-03-01

    Mildiomycin, a new nucleoside antibiotic, selectively inhibits protein synthesis in HeLa cells, and is less active in the inhibition of RNA or DNA synthesis. An increased inhibition of translation by mildiomycin is observed in cultured HeLa cells when they are permeabilized by encephalomyocarditis virus. This observation suggests that this antibiotic does not easily pass through the cell membrane, as occurs with other nucleoside and aminoglycoside antibiotics. The inhibition of translation is also observed in cell-free systems, such as endogenous protein synthesis in a rabbit reticulocyte lysate or the synthesis of polyphenylalanine directed by poly (U). Finally the mode of action of mildiomycin was investigated and the results suggest that the compound blocks the peptidyl-transferase center.

  3. Aminoglycoside binding to the HIV-1 RNA dimerization initiation site: thermodynamics and effect on the kissing-loop to duplex conversion

    OpenAIRE

    Bernacchi, Serena; Freisz, Séverine; Maechling, Clarisse; Spiess, Bernard; Marquet, Roland; Dumas, Philippe; Ennifar, Eric

    2007-01-01

    Owing to a striking, and most likely fortuitous, structural and sequence similarity with the bacterial 16 S ribosomal A site, the RNA kissing-loop complex formed by the HIV-1 genomic RNA dimerization initiation site (DIS) specifically binds 4,5-disubstituted 2-deoxystreptamine (2-DOS) aminoglycoside antibiotics. We used chemical probing, molecular modeling, isothermal titration calorimetry (ITC) and UV melting to investigate aminoglycoside binding to the DIS loop–loop complex. We showed that ...

  4. 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

  5. Performance evaluation of powdered activated carbon for removing 28 types of antibiotics from water.

    Science.gov (United States)

    Zhang, Xinbo; Guo, Wenshan; Ngo, Huu Hao; Wen, Haitao; Li, Nan; Wu, Wei

    2016-05-01

    Currently, the occurrence and fate of antibiotics in the aquatic environment has become a very serious problem in that they can potentially and irreversibly damage the ecosystem and human health. For this reason, interest has increased in developing strategies to remove antibiotics from water. This study evaluated the performance of powdered activated carbon (PAC) in removing from water 6 representative groups of 28 antibiotics, namely Tetracyclines (TCs), Macrolides (MCs), Chloramphenicols (CPs), Penicillins (PNs), Sulfonamides (SAs) and Quinolones (QNs). Results indicate that PAC demonstrated superior adsorption capacity for all selected antibiotics. The removal efficiency was up to 99.9% in deionized water and 99.6% in surface water at the optimum conditions with PAC dosage of 20 mg/L and contact time of 120 min. According to the Freundlich model's adsorption isotherm, the values of n varied among these antibiotics and most were less than 1, suggesting that the adsorption of antibiotics onto PAC was nonlinear. Adsorption of antibiotics followed well the pseudo-second-order kinetic model (R(2) = 0.99). Analysis using the Weber-Morris model revealed that the intra-particle diffusion was not the only rate-controlling step. Overall, the findings in this study confirm that PAC is a feasible and viable option for removing antibiotics from water in terms of water quality improvement and urgent antibiotics pollution control. Further research is essential on the following subjects: (i) removing more types of antibiotics by PAC; (ii) the adsorption process; and (iii) the mechanism of the competitive adsorption existing between natural organic matters (NOMs) and antibiotics. PMID:26946168

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

    Directory of Open Access Journals (Sweden)

    Teresita De Jesus eBello Gonzalez

    2016-01-01

    Full Text Available 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 Cellulosimicrobium spp. displayed increases in colony forming units during incubations in minimal medium with only antibiotics added, i.e. the antibiotic subsistence phenotype. Furthermore, laboratory strains of E. coli and Pseudomonas putida equipped with the aminoglycoside 3’phosphotransferase II gene also displayed the subsistence phenotype on aminoglycosides. In order to address which endogenous genes could be involved in these subsistence phenotypes, the broad-range glycosyl-hydrolase inhibiting iminosugar deoxynojirimycin (DNJ was used. Addition of DNJ to minimal medium containing glucose showed initial growth retardation of resistant E. coli, which was rapidly recovered to normal growth. In contrast, addition of DNJ to minimal medium containing kanamycin arrested resistant E. coli growth, suggesting that glycosyl-hydrolases were involved in the subsistence phenotype. However, antibiotic degradation experiments showed no reduction in kanamycin, even though the number of colony forming units increased. Although antibiotic subsistence phenotypes are readily observed in bacterial species, and are even found in susceptible laboratory strains carrying standard resistance genes, we conclude there is a discrepancy between the observed antibiotic subsistence phenotype and actual antibiotic degradation. Based on these results we can hypothesise that aminoglycoside modifying enzymes might first inactivate the antibiotic (i.e. by acetylation of amino groups, modification of hydroxyl groups by adenylation and phosphorylation respectively, before the subsequent action of catabolic enzymes. Even though we do not dispute that antibiotics could be used as a single carbon

  7. Aminoglycoside resistance rates, phenotypes, and mechanisms of Gram-negative bacteria from infected patients in upper Egypt.

    Directory of Open Access Journals (Sweden)

    Gamal F Gad

    Full Text Available With the re-emergence of older antibiotics as valuable choices for treatment of serious infections, we studied the aminoglycoside resistance of Gram-negative bacteria isolated from patients with ear, urinary tract, skin, and gastrointestinal tract infections at Minia university hospital in Egypt. Escherichia coli (mainly from urinary tract and gastrointestinal tract infections was the most prevalent isolate (28.57%, followed by Pseudomonas aeruginosa (25.7% (mainly from ear discharge and skin infections. Isolates exhibited maximal resistance against streptomycin (83.4%, and minimal resistance against amikacin (17.7% and intermediate degrees of resistance against neomycin, kanamycin, gentamicin, and tobramycin. Resistance to older aminoglycosides was higher than newer aminoglycosides. The most common aminoglycoside resistance phenotype was that of streptomycin resistance, present as a single phenotype or in combination, followed by kanamycin-neomycin as determined by interpretative reading. The resistant Pseudomonas aeruginosa strains were capable of producing aminoglycoside-modifying enzymes and using efflux as mechanisms of resistance. Using checkerboard titration method, the most frequently-observed outcome in combinations of aminoglycosides with β-lactams or quinolones was synergism. The most effective combination was amikacin with ciprofloxacin (100% Synergism, whereas the least effective combination was gentamicin with amoxicillin (53.3% Synergistic, 26.7% additive, and 20% indifferent FIC indices. Whereas the studied combinations were additive and indifferent against few of the tested strains, antagonism was never observed. The high resistance rates to aminoglycosides exhibited by Gram-negative bacteria in this study could be attributed to the selective pressure of aminoglycoside usage which could be controlled by successful implementation of infection control measures.

  8. 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

    2015-03-11

    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.

  9. Rescue of non-sense mutated p53 tumor suppressor gene by aminoglycosides

    OpenAIRE

    Floquet, Célia; Deforges, Jules; Rousset, Jean-Pierre; Bidou, Laure

    2010-01-01

    Mutation-based treatments are a new development in genetic medicine, in which the nature of the mutation dictates the therapeutic strategy. Interest has recently focused on diseases caused by premature termination codons (PTCs). Drugs inducing the readthrough of these PTCs restore the production of a full-length protein. In this study, we explored the possibility of using aminoglycoside antibiotics to induce the production of a full-length functional p53 protein from a gene carrying a PTC. We...

  10. Sodium-Glucose Transporter-2 (SGLT2; SLC5A2) Enhances Cellular Uptake of Aminoglycosides

    OpenAIRE

    Meiyan Jiang; Qi Wang; Takatoshi Karasawa; Ja-Won Koo; Hongzhe Li; Steyger, Peter S.

    2014-01-01

    Aminoglycoside antibiotics, like gentamicin, continue to be clinically essential worldwide to treat life-threatening bacterial infections. Yet, the ototoxic and nephrotoxic side-effects of these drugs remain serious complications. A major site of gentamicin uptake and toxicity resides within kidney proximal tubules that also heavily express electrogenic sodium-glucose transporter-2 (SGLT2; SLC5A2) in vivo. We hypothesized that SGLT2 traffics gentamicin, and promotes cellular toxicity. We conf...

  11. Enhancement of the Norfloxacin Antibiotic Activity by Gaseous Contact with the Essential Oil of Croton zehntneri

    OpenAIRE

    Coutinho, HDM; Matias, EFF; Santos, KKA; Tintino, SR; Souza, CES; Guedes, GMM; Santos, FAD; Costa, JGM; Falcão-Silva, VS; Siqueira-Júnior, JP

    2010-01-01

    This is the first on the modulation of norfloxacin antibiotic activity by the volatile compounds of an essential oil. We report the chemical composition and antibiotic modifying activity of the essential oil extracted from the leaves of Croton zehntneri Pax et Hoffm (variety estragole), using the minimal inhibitory dose method and gaseous contact. The leaves of Croton zehntneri Pax et Hoffm (Euphorbiaceae) were subjected to hydrodistillation, and the essential oil extracted was examined with ...

  12. Synergistic antimicrobial activity between pentacyclic triterpenoids and antibiotics against Staphylococcus aureus strains

    Directory of Open Access Journals (Sweden)

    Navaratnam Parasakthi

    2011-06-01

    Full Text Available Abstract Background There has been considerable effort to discover plant-derived antibacterials against methicillin-resistant strains of Staphylococcus aureus (MRSA which have developed resistance to most existing antibiotics, including the last line of defence, vancomycin. Pentacyclic triterpenoid, a biologically diverse plant-derived natural product, has been reported to show anti-staphylococcal activities. The objective of this study is to evaluate the interaction between three pentacyclic triterpenoid and standard antibiotics (methicillin and vancomycin against reference strains of Staphylococcus aureus. Methods and Results The activity of the standard antibiotics and compounds on reference methicillin-sensitive and resistant strains of S. aureus were determined using the macrodilution broth method. The minimum inhibitory concentration (MIC of the compounds was compared with that of the standard antibiotics. The interaction between any two antimicrobial agents was estimated by calculating the fractional inhibitory concentration (FIC index of the combination. The various combinations of antibiotics and compounds reduced the MIC to a range of 0.05 to 50%. Conclusion Pentacyclic triterpenoids have shown anti-staphylococcal activities and although individually weaker than common antibiotics produced from bacteria and fungi, synergistically these compounds may use different mechanism of action or pathways to exert their antimicrobial effects, as implicated in the lowered MICs. Therefore, the use of current antibiotics could be maintained in their combination with plant-derived antibacterial agents as a therapeutic option in the treatment of S. aureus infections.

  13. Enhanced Antimicrobial Activity Of Antibiotics Mixed With Metal Nanoparticles

    Science.gov (United States)

    Kumar, Sandeep; Kumar, Neeraj; Bhanjana, Gaurav; Thakur, Rajesh; Dilbaghi, Neeraj

    2011-12-01

    Current producers of antimicrobial technology have a long lasting, environmentally safe, non-leaching, water soluble solution that will eventually replace all poisons and heavy metals. The transition metal ions inevitably exist as metal complexes in biological systems by interaction with the numerous molecules possessing groupings capable of complexation or chelation. Nanoparticles of metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. the bacterial action of antibiotics like penicillin, erythryomycin, ampicillin, streptomycin, kanamycin etc. and that of a mixture of antibiotics and metal and metal oxide nanoparticles like zinc oxide, zirconium, silver and gold on microbes was examined by the agar-well-diffusion method, enumeration of colony-forming units (CFU) and turbidimetry.

  14. Structure, toxicity and antibiotic activity of gramicidin S and derivatives.

    Science.gov (United States)

    Swierstra, J; Kapoerchan, V; Knijnenburg, A; van Belkum, A; Overhand, M

    2016-05-01

    Development of new antibiotics is declining whereas antibiotic resistance is rising, heralding a post-antibiotic era. Antimicrobial peptides such as gramicidin S (GS), exclusively topically used due to its hemolytic side-effect, could still be interesting as therapeutic compounds. By modifying the amino-acid composition of GS, we synthesized GS analogues. We now show that derivative VK7 has a lower MIC (7.8-31.2 μg/ml, median 15.6 μg/ml) against strains of multi-drug resistant (MDR) Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa than GS has (3.9-62.5 μg/ml, median 31.3 μg/ml). Low MICs for both VK7 and GS were observed for Staphylococcus aureus and Enterococcus faecium. VK7 showed reduced haemolysis and less lactate dehydrogenase release. All compounds were fully bactericidal at MIC values. Modification of GS enables production of novel derivatives potentially useful for systemic treatment of human infections. PMID:26886453

  15. 糖尿病足分离的铜绿假单胞菌对氨基糖苷类抗生素耐药机制探讨%Study on aminoglycoside antibiotics resistance of Pseudomonas aeruginosa isolated from diabetic foot infections

    Institute of Scientific and Technical Information of China (English)

    乌洪芳; 孙茜; 李玉珠; 张敏; 孟玲玲; 李代清

    2015-01-01

    Objective To investigate the clinical features, phenotypes and genotypes of Pseudomonas aeruginosa (PA) strains isolated from patients with diabetic foot infection (DFI) resisting to aminoglycosides antibiotics (AmAn). Methods The clinical profiles of 209 DFI patients hospitalized in the Tianjin Metabolic Diseases Hospital were collected and ana⁃lyzed. Forty-one PA strains were identified, and their antibiotic resistance profiles were obtained. The DNAs of PA isolates were extracted and applied to amplifications for several aminoglycosides modifying enzyme genes, including aac(3′)-Ⅰ, aac (3′)-Ⅱ, aac(6′)-Ⅰb, aac(6′)-Ⅱ, ant(2′′)-Ⅰand ant(3′′)-Ⅰby PCR method. Combining with the clinical features and the antibiotic resistance profiles, the relationship between genotypes and phenotypes of the PA strains was analyzed. Results Gram positive bacteria (G+) were the majority of the pathogen with 51.67%detection rate. The total detection rate of PA was 19.62%, listed as the top one pathogenic bacterium among gram negative bacteria (47.67%). There was significant difference in the ratio of ulcer area≥4 cm2 between PA group and non-PA group and G+group. There were significantly higher inci⁃dence rate of ischemic ulcer and osteomyelitis in PA group than those of G+group. There were higher clinical characteristics and ulcer depth (SAD) score, and increased hypersensitive C-reactive protein in PA group than those of G+ group. There were 30 strains of PA being resistant to AmAn (73.17%). The predominant drug resistance gene to AmAn was ant(3′′)-Ⅰ(65.85%), and aac(3′)-Ⅰgene was not found from all PA isolates. Conclusion The detection rate of PA isolated from DFI patients was higher, and patients were with the characteristics of larger, deeper and severe ischemia of ulcer area. The phe⁃nomenon of PA resistant to AmAn was more serious, and ant(3′′)-Ⅰgene identified from PA isolates was the most common resistance gene identified to Am

  16. Aminoglycoside nephrotoxicity: modeling, simulation, and control.

    Science.gov (United States)

    Rougier, Florent; Claude, Daniel; Maurin, Michel; Sedoglavic, Alexandre; Ducher, Michel; Corvaisier, Stéphane; Jelliffe, Roger; Maire, Pascal

    2003-03-01

    The main constraints on the administration of aminoglycosides are the risks of nephrotoxicity and ototoxicity, which can lead to acute, renal, vestibular, and auditory toxicities. In the present study we focused on nephrotoxicity. No reliable predictor of nephrotoxicity has been found to date. We have developed a deterministic model which describes the pharmacokinetic behavior of aminoglycosides (with a two-compartment model), the kinetics of aminoglycoside accumulation in the renal cortex, the effects of aminoglycosides on renal cells, the resulting effects on renal function by tubuloglomerular feedback, and the resulting effects on serum creatinine concentrations. The pharmacokinetic parameter values were estimated by use of the NPEM program. The estimated pharmacodynamic parameter values were obtained after minimization of the least-squares objective function between the measured and the calculated serum creatinine concentrations. A simulation program assessed the influences of the dosage regimens on the occurrence of nephrotoxicity. We have also demonstrated the relevancy of modeling of the circadian rhythm of the renal function. We have shown the ability of the model to fit with 49 observed serum creatinine concentrations for a group of eight patients treated for endocarditis by comparison with 49 calculated serum creatinine concentrations (r(2) = 0.988; P < 0.001). We have found that for the same daily dose, the nephrotoxicity observed with a thrice-daily administration schedule appears more rapidly, induces a greater decrease in renal function, and is more prolonged than those that occur with less frequent administration schedules (for example, once-daily administration). Moreover, for once-daily administration, we have demonstrated that the time of day of administration can influence the incidence of aminoglycoside nephrotoxicity. The lowest level of nephrotoxicity was observed when aminoglycosides were administered at 1:30 p.m. Clinical application of this

  17. The role of active efflux in antibiotic - resistance of clinical isolates of Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Falsafi T

    2009-01-01

    Full Text Available Purpose: In gram-negative bacteria, active efflux pumps that excrete drugs can confer resistance to antibiotics however, in Helicobacter pylori this role is not well established. The purpose of this study is to evaluate the role of active efflux in resistance of H. pylori isolates to antibiotics. Materials and Methods: Twelve multiple antibiotic resistant (MAR isolates resistant to at least four antibiotics, including β-lactams, metronidazole, tetracycline, erythromycin, and ciprofloxacin; three resistant to only β-lactams, and two hyper-susceptible isolates, were obtained from screening of 96 clinical isolates of H. pylori . Their minimal inhibitory concentrations (MICs for antibiotics and ethidium-bromide (EtBr were compared in the presence- and absence of a proton-conductor, carbonyl cyanide-m chlorophenyl-hydrazone (CCCP using agar-dilution and disc diffusion. Drug accumulation studies for EtBr and antibiotics were assessed in the presence and absence of CCCP using spectrofluorometry. Results: MIC of EtBr for eight MAR-isolates was decreased two- to four-folds in the presence of CCCP, of which five showed reduced MICs for β-lactam, metronidazole, tetracycline, and ciprofloxacin with CCCP. Accumulation of EtBr by the MAR-isolates was rapid and not dependant on the pattern of multiple resistance. Antibiotic accumulation assay confirmed the presence of energy-dependant efflux of β-lactam, metronidazole, tetracycline, and ciprofloxacin, but no erythromycin in five MAR isolates. Energy-dependant efflux of EtBr or antibiotics was not observed for four MAR-isolates, and three isolates were resistant only to β-lactams. Conclusion: Energy-dependant efflux plays a role in the resistance of H. pylori clinical isolates to structurally unrelated antibiotics in a broadly specific multidrug efflux manner. Difference in the efflux potential of MAR isolates may be related to the presence or absence of functional efflux-pumps in diverse H. pylori

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

    Science.gov (United States)

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

    2016-06-01

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

  19. Intracellular Activity of Antibiotics against Staphylococcus aureus in a Mouse Peritonitis Model ▿

    OpenAIRE

    Sandberg, Anne; Hessler, Jonas H. R.; Skov, Robert L.; Blom, Jens; Frimodt-Møller, Niels

    2009-01-01

    Antibiotic treatment of Staphylococcus aureus infections is often problematic due to the slow response to therapy and the high frequency of infection recurrence. The intracellular persistence of staphylococci has been recognized and could offer a good explanation for these treatment difficulties. Knowledge of the interplay between intracellular antibiotic activity and the overall outcome of infection is therefore important. Several intracellular in vitro models have been developed, but few ex...

  20. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard; Lewenza, Shawn

    2015-11-09

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype.

  1. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard; Lewenza, Shawn

    2016-01-01

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype. PMID:26552982

  2. A Simple Assay to Screen Antimicrobial Compounds Potentiating the Activity of Current Antibiotics

    Science.gov (United States)

    Iqbal, Junaid; Kazmi, Shahana Urooj; Khan, Naveed Ahmed

    2013-01-01

    Antibiotic resistance continues to pose a significant problem in the management of bacterial infections, despite advances in antimicrobial chemotherapy and supportive care. Here, we suggest a simple, inexpensive, and easy-to-perform assay to screen antimicrobial compounds from natural products or synthetic chemical libraries for their potential to work in tandem with the available antibiotics against multiple drug-resistant bacteria. The aqueous extract of Juglans regia tree bark was tested against representative multiple drug-resistant bacteria in the aforementioned assay to determine whether it potentiates the activity of selected antibiotics. The aqueous extract of J. regia bark was added to Mueller-Hinton agar, followed by a lawn of multiple drug-resistant bacteria, Salmonella typhi or enteropathogenic E. coli. Next, filter paper discs impregnated with different classes of antibiotics were placed on the agar surface. Bacteria incubated with extract or antibiotics alone were used as controls. The results showed a significant increase (>30%) in the zone of inhibition around the aztreonam, cefuroxime, and ampicillin discs compared with bacteria incubated with the antibiotics/extract alone. In conclusion, our assay is able to detect either synergistic or additive action of J. regia extract against multiple drug-resistant bacteria when tested with a range of antibiotics. PMID:23865073

  3. A Simple Assay to Screen Antimicrobial Compounds Potentiating the Activity of Current Antibiotics

    Directory of Open Access Journals (Sweden)

    Junaid Iqbal

    2013-01-01

    Full Text Available Antibiotic resistance continues to pose a significant problem in the management of bacterial infections, despite advances in antimicrobial chemotherapy and supportive care. Here, we suggest a simple, inexpensive, and easy-to-perform assay to screen antimicrobial compounds from natural products or synthetic chemical libraries for their potential to work in tandem with the available antibiotics against multiple drug-resistant bacteria. The aqueous extract of Juglans regia tree bark was tested against representative multiple drug-resistant bacteria in the aforementioned assay to determine whether it potentiates the activity of selected antibiotics. The aqueous extract of J. regia bark was added to Mueller-Hinton agar, followed by a lawn of multiple drug-resistant bacteria, Salmonella typhi or enteropathogenic E. coli. Next, filter paper discs impregnated with different classes of antibiotics were placed on the agar surface. Bacteria incubated with extract or antibiotics alone were used as controls. The results showed a significant increase (>30% in the zone of inhibition around the aztreonam, cefuroxime, and ampicillin discs compared with bacteria incubated with the antibiotics/extract alone. In conclusion, our assay is able to detect either synergistic or additive action of J. regia extract against multiple drug-resistant bacteria when tested with a range of antibiotics.

  4. Correction: Membrane-active macromolecules resensitize NDM-1 gram-negative clinical isolates to tetracycline antibiotics.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1 producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMsthat restore the antibacterial efficacy (enhancement by >80-1250 fold of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates.Organismic studies showed that bacteria had an increased and faster uptake of tetracyclinein the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover,bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.

  5. Membrane-active macromolecules resensitize NDM-1 gram-negative clinical isolates to tetracycline antibiotics.

    Directory of Open Access Journals (Sweden)

    Divakara S S M Uppu

    Full Text Available Gram-negative 'superbugs' such as New Delhi metallo-beta-lactamase-1 (blaNDM-1 producing pathogens have become world's major public health threats. Development of molecular strategies that can rehabilitate the 'old antibiotics' and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs that restore the antibacterial efficacy (enhancement by >80-1250 fold of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates. Organismic studies showed that bacteria had an increased and faster uptake of tetracycline in the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover, bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs.

  6. Isolation and speciation of Enterococci from various clinical samples and their antimicrobial susceptibility pattern with special reference to high level Aminoglycoside resistance

    Directory of Open Access Journals (Sweden)

    :Saroj Golia, Nirmala AR, Asha S Kamath B

    2014-07-01

    Full Text Available Background and Objectives: Enterococci are important nosocomial agents and strains resistant to penicillin and other antibiotics occur frequently. Enterococci are intrinsically resistant to cephalosporins and offer low level resistance to aminoglycosides. In penicillin sensitive strains, synergism occurs with combination treatment with penicillin and aminoglycoside. Serious infections caused by them are treated with penicillin and aminoglycoside combination. But the synergistic effect is lost, when the strain develops high level aminoglycoside resistance. The choice of drug for infections due to such strains is vancomycin. The present study was carried out to isolate and speciate Enterococci from various clinical samples, to know the susceptibility pattern of the isolates, to determine the High Level Aminoglycoside Resistance (HLAR among Enterococcal isolates. Methods: A total of One hundred Enterococcal species isolated from various clinical samples were identified by various biochemical reactions. Antimicrobial susceptibility testing and HLAR were determined by Kirby- Bauer disc diffusion method. Results: Out of 100 Enterococcal isolates, 59 were E. faecalis, 38 were E. faecium, 3 were other Enterococcal species. Among these 53 isolates showed High Level Aminoglycoside Resistance. Conclusion: Present study shows the presence of drug resistance to most of commonly used antibiotics and HLAR is also more in E.faecium compared to E.fecalis.

  7. Synergistic antibacterial activity of Salvia officinalis and Cichorium intybus extracts and antibiotics.

    Science.gov (United States)

    Stefanović, Olgica D; Stanojević, Dragana D; Comić, Ljiljana R

    2012-01-01

    Synergistic activity of Salvia officinalis and Cichorium intybus extracts and commonly used antibiotics, amoxicillin and chloramphenicol, were evaluated. Interactions between plant extracts and antibiotics were tested by checkerboard method and interpreted as FIC index. Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and clinical isolates Staphylococcus aureus, Bacillus subtilis, Enterobacter cloacae, Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis were used. Salvia officinalis showed better synergistic capacity than Cichorium intybus. Synergistic interactions were observed between amoxicillin and acetone or ethyl acetate extract of Salvia officinalis and between chloramphenicol and ethyl acetate extract of Salvia officinalis. In the presence of sub-inhibitory concentration (1/4 MIC to 1/32 MIC) of sage extracts, the MIC values of antibiotics were decreased by 2- to 10-fold. Synergism was observed against all test bacteria, except Escherichia coli. The combinations of acetone and ethyl acetate extract from Cichorium intybus and antibiotics resulted in additive and indifferent effects against tested bacteria.

  8. 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.

  9. Disinfectant and antibiotic activities: a comparative analysis in Brazilian hospital bacterial isolates

    Directory of Open Access Journals (Sweden)

    Guimarães Márcia Aparecida

    2000-01-01

    Full Text Available Nosocomial infections are an important cause of morbidity and mortality all over the world. It has been shown that appropriate environmental hygienic and disinfection practices can be very helpful to hospital infection control. The purpose of this study was to evaluate the bactericidal activity of some disinfectants against antibiotic-susceptible and antibiotic-resistant hospital bacterial isolates. The susceptibility of 27 clinical isolates to disinfectants and antibiotics was determined by the Association of Official Analytical Chemist?s (AOAC Use-Dilution method and by the Kirby-Bauer method, respectively. All strains tested were susceptible to sodium hypochlorite, glutaraldehyde and to the association quaternary ammonium - formaldehyde - ethyl alcohol disinfectants. However, the susceptibility of strains to phenol and to one quaternary ammonium compound was variable. Among twenty-one antibiotic-multiresistant strains (methicillin-resistant staphylococci, Enterococcus spp, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens and Escherichia coli eleven (52% and eight (38% strains were resistant to the quaternary ammonium and phenol compounds, respectively. Among six isolates that demonstrated susceptibility to antibiotics (staphylococci, Enterococcus spp, P. mirabilis, E. cloacae and E. coli two strains (33% showed resistance to these disinfectants. The results demonstrated the lack of correlation between antibiotic-susceptibility and susceptibility to disinfectants in hospital strains.

  10. Association of community antibiotic consumption with clinically active trachoma in rural Ethiopia.

    Science.gov (United States)

    Ayele, Berhan; Belay, Tesfaye; Gebre, Teshome; Zerihun, Mulat; Amere, Abayneh; Assefa, Yared; Habte, Dereje; Loh, Allison R; Stoller, Nicole E; Keenan, Jeremy D

    2011-12-01

    Community antibiotic utilization and its relationship with trachoma has been poorly characterized in areas with endemic trachoma. A survey of all drug-dispensing facilities in an area of rural Ethiopia was conducted. Antibiotic use was calculated using both retrospective and prospective methodology, and expressed as defined daily doses (DDDs). Overall antibiotic consumption estimates ranged from 2.91 to 3.07 DDDs per 1000 person days. Macrolide antibiotics accounted for 0.01 to 0.02 DDDs per 1000 person days. Each additional DDD of antibiotic use per 1000 person days was associated with a 15.0% (95% CI -19.7 to -10.3) decrease in the prevalence of clinically active trachoma among children under 10 years of age after adjusting for age, gender, altitude and the distance to nearest town. Increased background community antibiotic use may therefore be an aspect of socioeconomic development that can partially explain why trachoma prevalence has decreased in some areas in the absence of a trachoma program. The low volume of macrolide consumption in this area suggests that selection for nasopharyngeal pneumococcal macrolide resistance after mass azithromycin treatments likely has little clinical significance. PMID:22247750

  11. Systematically Altering Bacterial SOS Activity under Stress Reveals Therapeutic Strategies for Potentiating Antibiotics.

    Science.gov (United States)

    Mo, Charlie Y; Manning, Sara A; Roggiani, Manuela; Culyba, Matthew J; Samuels, Amanda N; Sniegowski, Paul D; Goulian, Mark; Kohli, Rahul M

    2016-01-01

    The bacterial SOS response is a DNA damage repair network that is strongly implicated in both survival and acquired drug resistance under antimicrobial stress. The two SOS regulators, LexA and RecA, have therefore emerged as potential targets for adjuvant therapies aimed at combating resistance, although many open questions remain. For example, it is not well understood whether SOS hyperactivation is a viable therapeutic approach or whether LexA or RecA is a better target. Furthermore, it is important to determine which antimicrobials could serve as the best treatment partners with SOS-targeting adjuvants. Here we derived Escherichia coli strains that have mutations in either lexA or recA genes in order to cover the full spectrum of possible SOS activity levels. We then systematically analyzed a wide range of antimicrobials by comparing the mean inhibitory concentrations (MICs) and induced mutation rates for each drug-strain combination. We first show that significant changes in MICs are largely confined to DNA-damaging antibiotics, with strains containing a constitutively repressed SOS response impacted to a greater extent than hyperactivated strains. Second, antibiotic-induced mutation rates were suppressed when SOS activity was reduced, and this trend was observed across a wider spectrum of antibiotics. Finally, perturbing either LexA or RecA proved to be equally viable strategies for targeting the SOS response. Our work provides support for multiple adjuvant strategies, while also suggesting that the combination of an SOS inhibitor with a DNA-damaging antibiotic could offer the best potential for lowering MICs and decreasing acquired drug resistance. IMPORTANCE Our antibiotic arsenal is becoming depleted, in part, because bacteria have the ability to rapidly adapt and acquire resistance to our best agents. The SOS pathway, a widely conserved DNA damage stress response in bacteria, is activated by many antibiotics and has been shown to play central role in

  12. Systematically Altering Bacterial SOS Activity under Stress Reveals Therapeutic Strategies for Potentiating Antibiotics.

    Science.gov (United States)

    Mo, Charlie Y; Manning, Sara A; Roggiani, Manuela; Culyba, Matthew J; Samuels, Amanda N; Sniegowski, Paul D; Goulian, Mark; Kohli, Rahul M

    2016-01-01

    The bacterial SOS response is a DNA damage repair network that is strongly implicated in both survival and acquired drug resistance under antimicrobial stress. The two SOS regulators, LexA and RecA, have therefore emerged as potential targets for adjuvant therapies aimed at combating resistance, although many open questions remain. For example, it is not well understood whether SOS hyperactivation is a viable therapeutic approach or whether LexA or RecA is a better target. Furthermore, it is important to determine which antimicrobials could serve as the best treatment partners with SOS-targeting adjuvants. Here we derived Escherichia coli strains that have mutations in either lexA or recA genes in order to cover the full spectrum of possible SOS activity levels. We then systematically analyzed a wide range of antimicrobials by comparing the mean inhibitory concentrations (MICs) and induced mutation rates for each drug-strain combination. We first show that significant changes in MICs are largely confined to DNA-damaging antibiotics, with strains containing a constitutively repressed SOS response impacted to a greater extent than hyperactivated strains. Second, antibiotic-induced mutation rates were suppressed when SOS activity was reduced, and this trend was observed across a wider spectrum of antibiotics. Finally, perturbing either LexA or RecA proved to be equally viable strategies for targeting the SOS response. Our work provides support for multiple adjuvant strategies, while also suggesting that the combination of an SOS inhibitor with a DNA-damaging antibiotic could offer the best potential for lowering MICs and decreasing acquired drug resistance. IMPORTANCE Our antibiotic arsenal is becoming depleted, in part, because bacteria have the ability to rapidly adapt and acquire resistance to our best agents. The SOS pathway, a widely conserved DNA damage stress response in bacteria, is activated by many antibiotics and has been shown to play central role in

  13. Systematically Altering Bacterial SOS Activity under Stress Reveals Therapeutic Strategies for Potentiating Antibiotics

    Science.gov (United States)

    Mo, Charlie Y.; Manning, Sara A.; Roggiani, Manuela; Culyba, Matthew J.; Samuels, Amanda N.; Sniegowski, Paul D.; Goulian, Mark

    2016-01-01

    ABSTRACT The bacterial SOS response is a DNA damage repair network that is strongly implicated in both survival and acquired drug resistance under antimicrobial stress. The two SOS regulators, LexA and RecA, have therefore emerged as potential targets for adjuvant therapies aimed at combating resistance, although many open questions remain. For example, it is not well understood whether SOS hyperactivation is a viable therapeutic approach or whether LexA or RecA is a better target. Furthermore, it is important to determine which antimicrobials could serve as the best treatment partners with SOS-targeting adjuvants. Here we derived Escherichia coli strains that have mutations in either lexA or recA genes in order to cover the full spectrum of possible SOS activity levels. We then systematically analyzed a wide range of antimicrobials by comparing the mean inhibitory concentrations (MICs) and induced mutation rates for each drug-strain combination. We first show that significant changes in MICs are largely confined to DNA-damaging antibiotics, with strains containing a constitutively repressed SOS response impacted to a greater extent than hyperactivated strains. Second, antibiotic-induced mutation rates were suppressed when SOS activity was reduced, and this trend was observed across a wider spectrum of antibiotics. Finally, perturbing either LexA or RecA proved to be equally viable strategies for targeting the SOS response. Our work provides support for multiple adjuvant strategies, while also suggesting that the combination of an SOS inhibitor with a DNA-damaging antibiotic could offer the best potential for lowering MICs and decreasing acquired drug resistance. IMPORTANCE Our antibiotic arsenal is becoming depleted, in part, because bacteria have the ability to rapidly adapt and acquire resistance to our best agents. The SOS pathway, a widely conserved DNA damage stress response in bacteria, is activated by many antibiotics and has been shown to play central role

  14. Methanobactin: a copper binding compound having antibiotic and antioxidant activity isolated from methanotrophic bacteria

    Science.gov (United States)

    DiSpirito, Alan A.; Zahn, James A.; Graham, David W.; Kim, Hyung J.; Alterman, Michail; Larive, Cynthia

    2007-04-03

    A means and method for treating bacterial infection, providing antioxidant activity, and chelating copper using a copper binding compound produced by methanotrophic bacteria is described. The compound, known as methanobactin, is the first of a new class of antibiotics having gram-positive activity. Methanobactin has been sequenced, and its structural formula determined.

  15. Medical-grade honey enriched with antimicrobial peptides has enhanced activity against antibiotic-resistant pathogens

    NARCIS (Netherlands)

    P.H.S. Kwakman; L. de Boer; C.P. Ruyter-Spira; T. Creemers-Molenaar; J.P.F.G. Helsper; C.M.J.E. Vandenbroucke-Grauls; S.A.J. Zaat; A.A. te Velde

    2011-01-01

    Honey has potent activity against both antibiotic-sensitive and -resistant bacteria, and is an interesting agent for topical antimicrobial application to wounds. As honey is diluted by wound exudate, rapid bactericidal activity up to high dilution is a prerequisite for its successful application. We

  16. Evolution of an Antibiotic Resistance Enzyme Constrained by Stability and Activity Trade-offs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K. (NWU)

    2010-03-08

    Pressured by antibiotic use, resistance enzymes have been evolving new activities. Does such evolution have a cost? To investigate this question at the molecular level, clinically isolated mutants of the {beta}-lactamase TEM-1 were studied. When purified, mutant enzymes had increased activity against cephalosporin antibiotics but lost both thermodynamic stability and kinetic activity against their ancestral targets, penicillins. The X-ray crystallographic structures of three mutant enzymes were determined. These structures suggest that activity gain and stability loss is related to an enlarged active site cavity in the mutant enzymes. In several clinically isolated mutant enzymes, a secondary substitution is observed far from the active site (Met182 {yields} Thr). This substitution had little effect on enzyme activity but restored stability lost by substitutions near the active site. This regained stability conferred an advantage in vivo. This pattern of stability loss and restoration may be common in the evolution of new enzyme activity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Byrnes, Laura J. [Stanford Synchrotron Radiation Laboratory, Stanford University, Menlo Park, CA 94025 (United States); Badarau, Adriana; Vakulenko, Sergei B. [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)

    2008-02-01

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

  18. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

    International Nuclear Information System (INIS)

    The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. - Terrestrial ecotoxicological effects of antibiotics are related to their sorption and degradation behavior in soil.

  19. Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

    Energy Technology Data Exchange (ETDEWEB)

    Liu Feng [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Ying Guangguo, E-mail: guangguo.ying@gmail.co [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Tao Ran; Zhao Jianliang; Yang Jifeng [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Tianhe District, Guangzhou 510640 (China); Zhao Lanfeng [College of Resource and Environmental Science, South China Agricultural University, Guangzhou 510642 (China)

    2009-05-15

    The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities. - Terrestrial ecotoxicological effects of antibiotics are related to their sorption and degradation behavior in soil.

  20. Membrane-Active Macromolecules Resensitize NDM-1 Gram-Negative Clinical Isolates to Tetracycline Antibiotics

    Science.gov (United States)

    Uppu, Divakara S. S. M.; Manjunath, Goutham B.; Yarlagadda, Venkateswarlu; Kaviyil, Jyothi E.; Ravikumar, Raju; Paramanandham, Krishnamoorthy; Shome, Bibek R.; Haldar, Jayanta

    2015-01-01

    Gram-negative ‘superbugs’ such as New Delhi metallo-beta-lactamase-1 (blaNDM-1) producing pathogens have become world’s major public health threats. Development of molecular strategies that can rehabilitate the ‘old antibiotics’ and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs) that restore the antibacterial efficacy (enhancement by >80-1250 fold) of tetracycline antibiotics towards blaNDM-1 Klebsiella pneumonia and blaNDM-1 Escherichia coli clinical isolates. Organismic studies showed that bacteria had an increased and faster uptake of tetracycline in the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover, bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards blaNDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs. PMID:25789871

  1. Physiological and Molecular Pathology of Aminoglycoside Ototoxicity

    Science.gov (United States)

    Sha, Su-Hua

    2005-01-01

    The problem of aminoglycoside-induced ototoxicity, which was recognized within a year of the discovery of streptomycin to combat tuberculosis in 1944, is still of great concern due to the widespread use of these powerful antibacterial agents. These drugs can damage to varying degrees the cochlea and vestibular system. Their primary targets are the…

  2. Molecular Epidemiology of Aminoglycosides Resistance in Acinetobacter Spp. with Emergence of Multidrug-Resistant Strains

    Directory of Open Access Journals (Sweden)

    MH Nazem Shirazi

    2010-06-01

    Full Text Available Background: Acinetobacter spp. is characterized as an important nosocomial pathogen and increasing antimicrobial resistance. Our aim was to evaluate antimicrobial susceptibility and aminoglycosides resistance genes of Acinetobacter spp. isolated from hospitalized patients.Methods: Sixty isolates were identified as Acinetobacter species. The isolates were tested for antibiotic resistance by disc diffusion method for 12 antimicrobials. The presence of aphA6, aacC1 aadA1, and aadB genes were detected using PCR.Results: From the isolated Acinetobacter spp. the highest resistance rate showed against amikacin, tobramycin, and ceftazidim, respectively; while isolated bacteria were more sensitive to ampicillic/subactam. More than 66% of the isolates were resistant to at least three classes of antibiotics, and 27.5% of MDR strains were resistant to all seven tested classes of antimicrobials. The higher MDR rate presented in bacteria isolated from the ICU and blood samples. More than 60% of the MDR bacteria were resistance to amikacin, ceftazidim, ciprofloxacin, piperacillin/tazobactam, doxycycline, tobramycin and levofloxacin. Also, more than 60% of the isolates contained phosphotransferase aphA6, and acetyltransferase genes aacC1, but adenylyltransferase genes aadA1 (41.7%, and aadB (3.3% were less prominent. 21.7% of the strains contain three aminoglycoside resistance genes (aphA6, aacC1 and aadA1.Conclusion: The rising trend of resistance to aminoglycosides poses an alarming threat to treatment of such infections. The findings showed that clinical isolates of Acinetobacter spp. in our hospital carrying various kinds of aminoglycoside resistance genes.

  3. Structural basis for dual nucleotide selectivity of aminoglycoside 2''-phosphotransferase IVa provides insight on determinants of nucleotide specificity of aminoglycoside kinases.

    Science.gov (United States)

    Shi, Kun; Berghuis, Albert M

    2012-04-13

    Enzymatic phosphorylation through a family of enzymes called aminoglycoside O-phosphotransferases (APHs) is a major mechanism by which bacteria confer resistance to aminoglycoside antibiotics. Members of the APH(2″) subfamily are of particular clinical interest because of their prevalence in pathogenic strains and their broad substrate spectra. APH(2″) enzymes display differential preferences between ATP or GTP as the phosphate donor, with aminoglycoside 2″-phosphotransferase IVa (APH(2″)-IVa) being a member that utilizes both nucleotides at comparable efficiencies. We report here four crystal structures of APH(2″)-IVa, two of the wild type enzyme and two of single amino acid mutants, each in complex with either adenosine or guanosine. Together, these structures afford a detailed look at the nucleoside-binding site architecture for this enzyme and reveal key elements that confer dual nucleotide specificity, including a solvent network in the interior of the nucleoside-binding pocket and the conformation of an interdomain linker loop. Steady state kinetic studies, as well as sequence and structural comparisons with members of the APH(2″) subfamily and other aminoglycoside kinases, rationalize the different substrate preferences for these enzymes. Finally, despite poor overall sequence similarity and structural homology, analysis of the nucleoside-binding pocket of APH(2″)-IVa shows a striking resemblance to that of eukaryotic casein kinase 2 (CK2), which also exhibits dual nucleotide specificity. These results, in complement with the multitude of existing inhibitors against CK2, can serve as a structural basis for the design of nucleotide-competitive inhibitors against clinically relevant APH enzymes.

  4. In vitro effect of levofloxacin and vancomycin combination against high level aminoglycoside-resistant enterococci.

    Science.gov (United States)

    Erdem, Ilknur; Cicek-Senturk, Gonul; Yucesoy-Dede, Behiye; Yuksel-Kocdogan, Funda; Yuksel, Saim; Karagul, Emin

    2004-01-01

    The in vitro effects of levofloxacin and vancomycin in combination were evaluated against high level aminoglycoside-resistant (HLAR) enterococci using chequerboard and time-kill curve techniques. We examined 28 strains of enterococci comprising 17 Enterococcus faecalis, 10 E. faecium and one E. durans. The combination of vancomycin and levofloxacin had indifferent activity against all isolates according to chequerboard microdilution method, but was synergistic for two isolates, one E. faecium and one E. faecalis, using the time-kill curve method. Both strains were levofloxacin resistant and had high level aminoglycoside resistance to gentamicin and streptomycin. Antagonism was not detected in any strain. The results of this study suggested that the combination of vancomycin with levofloxacin does not often show synergistic effect against high level aminoglycoside-resistant enterococci.

  5. Cooperative Electrostatic Polymer-Antibiotic Nanoplexes

    OpenAIRE

    Vadala, Timothy Patrick

    2010-01-01

    Many pathogenic bacteria can enter phagocytic cells and replicate in them, and these intracellular bacteria are difficult to treat because the recommended antibiotics do not transport into the cells efficiently. Examples include food-borne bacteria such as Salmonella and Listeria as well as more toxic bacteria such as Brucella and the Mycobacteria that lead to tuberculosis. Current treatments utilize aminoglycoside antibiotics that are polar and positively charged and such drugs do not ente...

  6. In vitro activity of antibiotics alone and in combination against Actinobacillus actinomycetemcomitans.

    Science.gov (United States)

    Yogev, R; Shulman, D; Shulman, S T; Glogowski, W G

    1986-01-01

    The MICs for 90% of the organisms tested (MIC90S) of 11 antibiotics against 24 clinical isolates of Actinobacillus actinomycetemcomitans were determined by the MIC 2000 system. The lowest MIC90S (16 micrograms/ml) were observed with ceftriaxone and rifampin. The next lowest MIC90S were found with cephapirin, tetracycline, and chloramphenicol (3.12 micrograms/ml). The MIC90S of penicillin, ampicillin, ticarcillin, piperacillin, and amikacin were each greater than or equal to 12.5 micrograms/ml. Antibiotic synergy was studied by the killing curve method and was defined as a greater than or equal to 2 log10 reduction in CFU when two antibiotics were used in combination at one-fourth the MBC for each compared with the effect of each antibiotic alone at one-half the MBC. Synergism between rifampin and penicillin, cephapirin, or ceftriaxone was tested for with 12 A. actinomycetemcomitans strains. In 7 of 37 instances, synergism was demonstrated for the combinations rifampin plus ceftriaxone (n = 3) or rifampin plus penicillin (n = 4); in 9 instances, an additive effect was noted, and impaired killing with drug combinations compared with the effect of a single antibiotic was suggested in 4 strains. The majority of strains were indifferent to the combinations. Similarly, variable results were observed when the combination of trimethoprim and cephapirin was tested against eight A. actinomycetemcomitans strains. Our data suggest that rifampin and cephapirin are the most active of the 11 antibiotics studied against A. actinomycetemcomitans. In addition, in vitro synergism between rifampin and other antibiotics or between trimethoprim and cephapirin was not consistently demonstrable.

  7. ENZYMATIC ACTIVITY AND ANTIBIOTIC RESISTANCE PROFILE OF LACTOBACILLUS PARACASEI SSP. PARACASEI-1 ISOLATED FROM REGIONAL YOGURTS OF BANGLADESH

    Directory of Open Access Journals (Sweden)

    Ummay Honi

    2013-12-01

    Full Text Available Lactobacillus paracasei ssp. paracasei-1 was identified from traditional yogurts of Khulna region, Bangladesh and its enzyme and antibiotic resistance profiles were determined. A commercially available API Zym kit was employed to determine the activities of 19 different enzymes. We found that L. paracasei ssp. paracasei-1 showed strong activities for several enzymes, viz. leucine arylamidase, valine arylamidase, napthol-AS-BI-phosphohydrolase, β-galactosidase, α –Glucosidase, N-Acetyl- β- glucosaminidase while activities for other enzymes were absent. Antibiotic resistance profile was assessed by minimum inhibitory concentration (MIC test for 61 major antibiotics and 4 antifungal agents obtained from commercial sources in MRS Agar media. The strain generally showed resistance to gram negative spectrum antibiotic while it showed susceptibility towards β-lactam antibiotic to gram positive spectrum antibiotic. The findings provide the therapeutic basis of using L. paracasei ssp. paracasei-1 in finished food products.

  8. Martinomycin, a new polyether antibiotic produced by Streptomyces salvialis. I. Taxonomy, fermentation and biological activity.

    Science.gov (United States)

    Bernan, V S; Montenegro, D A; Goodman, J J; Alluri, M R; Carter, G T; Abbanat, D R; Pearce, C J; Maiese, W M; Greenstein, M

    1994-12-01

    Actinomycete culture LL-D37187 has been found to produce the new polyether antibiotic martinomycin. Taxonomic studies, including morphological, physiological, and cell wall chemistry analyses, revealed that culture LL-D37187 is a novel streptomycete species, and the proposed name is Streptomyces salvialis. Martinomycin exhibits activity against the Southern Army Worm (Spodoptera eridania) and Gram-positive bacteria. PMID:7844037

  9. Transition Metal–α-Amino Acid Complexes with Antibiotic Activity against Mycobacterium spp.

    OpenAIRE

    Karpin, George W.; Merola, Joseph S.; Joseph O. Falkinham

    2013-01-01

    Synthetic iridium-, rhodium-, and ruthenium-amino acid complexes with hydrophobic l-amino acids have antibiotic activity against Mycobacterium spp., including Mycobacterium bovis BCG and the rapidly growing species Mycobacterium abscessus and Mycobacterium chelonae. Concentrations of transition metal-amino acid complexes demonstrating hemolysis or cytotoxicity were 10- to 25-fold higher than were the MICs.

  10. Syntheses and In Vitro Biological Activity of Some Derivatives of C-9154 Antibiotic

    Directory of Open Access Journals (Sweden)

    Isaac Asusheyi Bello

    2012-01-01

    Full Text Available In our continued attempts at designing new antibiotics based on the structure of the C-9154 antibiotic, to simultaneously improve activity and lower toxicity, an analogue to the C-9154 antibiotic and six derivatives of this analogue were synthesized. The approach was to significantly reduce the polarity of the synthesized analogue in the derivatives to achieve increased permeability across cell membranes by conversion of the highly polar carboxylic group to an ester functional group. The compounds were synthesized using a two-step reaction which involved an additional reaction between benzyl amine and maleic anhydride and then conversion of the terminal carboxylic acid functional group to an ester functional group using a thionyl chloride mediated esterification reaction. The compounds were fully characterized using Infrared, GC-MS, and 1D and 2D NMR experiments. The in vitro biological activity of the compounds showed that the derivatives were more active than the analogues as was anticipated with minimum inhibitory concentration in the range 0.625–5 μg/mL. The analogue had minimum inhibitory concentration in the range 2.5–10 μg/mL. These values are significantly better than that obtained for the original C-9154 antibiotic which had activity in the range 10–>100 μg/mL.

  11. Berberine Enhances the Antibacterial Activity of Selected Antibiotics against Coagulase-Negative Staphylococcus Strains in Vitro

    Directory of Open Access Journals (Sweden)

    Robert D. Wojtyczka

    2014-05-01

    Full Text Available Synergistic interactions between commonly used antibiotics and natural bioactive compounds may exhibit therapeutic benefits in a clinical setting. Berberine, an isoquinoline-type alkaloid isolated from many kinds of medicinal plants, has proven efficacy against a broad spectrum of microorganisms. The aim of the presented work was to assess the antibacterial activity of berberine chloride in light of the effect exerted by common antibiotics on fourteen reference strains of Staphylococccus spp., and to evaluate the magnitude of interactions of berberine with these antistaphylococcal antibiotics. In our study minimum inhibitory concentrations (MIC of berberine chloride against CoNS ranged from 16 to 512 µg/mL. The most noticeable effects were observed for S. haemolyticus ATCC 29970, S. epidermidis ATCC 12228, S. capitis subsp. capitis ATCC 35661, S. galinarium ATCC 700401, S. hominis subsp. hominis ATCC 27844, S. intermedius ATCC 29663 and S. lugdunensis ATCC 49576. The most significant synergistic effect was noticed for berberine in combination with linezolid, cefoxitin and erythromycin. The synergy between berberine and antibiotics demonstrates the potential application of compound combinations as an efficient, novel therapeutic tool for antibiotic-resistant bacterial infections.

  12. Using wildlife activity and antibiotic resistance analysis to model bacterial water quality in coastal ponds

    OpenAIRE

    Pullaro, Thomas C.; Pan, Wei; Chiovarou, Erica D.; Daugomah, James W.; Shea, Norman R.; Siewicki, Thomas C.

    2009-01-01

    Models that help predict fecal coliform bacteria (FCB) levels in environmental waters can be important tools for resource managers. In this study, we used animal activity along with antibiotic resistance analysis (ARA), land cover, and other variables to build models that predict bacteria levels in coastal ponds that discharge into an estuary. Photographic wildlife monitoring was used to estimate terrestrial and aquatic wildlife activity prior to sampling. Increased duck activity was an impor...

  13. Aminoglycoside binding to the HIV-1 RNA dimerization initiation site: thermodynamics and effect on the kissing-loop to duplex conversion.

    Science.gov (United States)

    Bernacchi, Serena; Freisz, Séverine; Maechling, Clarisse; Spiess, Bernard; Marquet, Roland; Dumas, Philippe; Ennifar, Eric

    2007-01-01

    Owing to a striking, and most likely fortuitous, structural and sequence similarity with the bacterial 16 S ribosomal A site, the RNA kissing-loop complex formed by the HIV-1 genomic RNA dimerization initiation site (DIS) specifically binds 4,5-disubstituted 2-deoxystreptamine (2-DOS) aminoglycoside antibiotics. We used chemical probing, molecular modeling, isothermal titration calorimetry (ITC) and UV melting to investigate aminoglycoside binding to the DIS loop-loop complex. We showed that apramycin, an aminoglycoside containing a bicyclic moiety, also binds the DIS, but in a different way than 4,5-disubstituted 2-DOS aminoglycosides. The determination of thermodynamic parameters for various aminoglycosides revealed the role of the different rings in the drug-RNA interaction. Surprisingly, we found that the affinity of lividomycin and neomycin for the DIS (K(d) approximately 30 nM) is significantly higher than that obtained in the same experimental conditions for their natural target, the bacterial A site (K(d) approximately 1.6 microM). In good agreement with their respective affinity, aminoglycoside increase the melting temperature of the loop-loop interaction and also block the conversion from kissing-loop complex to extended duplex. Taken together, our data might be useful for selecting new molecules with improved specificity and affinity toward the HIV-1 DIS RNA. PMID:17942426

  14. Antibacterial Activity of Propolis Ethanol Extract against Antibiotic Resistance

    OpenAIRE

    Maryam Mohammadi-Sichani; Farzaneh Zeighampour; Elaheh Shams; Nafiseh Sadat NaghaviP

    2014-01-01

    Background: Burn wound is a suitable site for incidence of resistant infections; thus, the research for finding effective drugs against this infection is necessary. The purpose of this study was to determine antibacterial activity of Isfahan bee propolis extracts against beta-lactamase producing bacteria isolated from burn wound infections. Materials and Methods: Ethanol extract of Isfahan bee propolis was prepared by 28 g of propolis in 100 ml of 70% ethanol. Antibacterial activity of eth...

  15. Evaluation of Antibiotics Active against Methicillin-Resistant Staphylococcus aureus Based on Activity in an Established Biofilm.

    Science.gov (United States)

    Meeker, Daniel G; Beenken, Karen E; Mills, Weston B; Loughran, Allister J; Spencer, Horace J; Lynn, William B; Smeltzer, Mark S

    2016-10-01

    We used in vitro and in vivo models of catheter-associated biofilm formation to compare the relative activity of antibiotics effective against methicillin-resistant Staphylococcus aureus (MRSA) in the specific context of an established biofilm. The results demonstrated that, under in vitro conditions, daptomycin and ceftaroline exhibited comparable activity relative to each other and greater activity than vancomycin, telavancin, oritavancin, dalbavancin, or tigecycline. This was true when assessed using established biofilms formed by the USA300 methicillin-resistant strain LAC and the USA200 methicillin-sensitive strain UAMS-1. Oxacillin exhibited greater activity against UAMS-1 than LAC, as would be expected, since LAC is an MRSA strain. However, the activity of oxacillin was less than that of daptomycin and ceftaroline even against UAMS-1. Among the lipoglycopeptides, telavancin exhibited the greatest overall activity. Specifically, telavancin exhibited greater activity than oritavancin or dalbavancin when tested against biofilms formed by LAC and was the only lipoglycopeptide capable of reducing the number of viable bacteria below the limit of detection. With biofilms formed by UAMS-1, telavancin and dalbavancin exhibited comparable activity relative to each other and greater activity than oritavancin. Importantly, ceftaroline was the only antibiotic that exhibited greater activity than vancomycin when tested in vivo in a murine model of catheter-associated biofilm formation. These results emphasize the need to consider antibiotics other than vancomycin, most notably, ceftaroline, for the treatment of biofilm-associated S. aureus infections, including by the matrix-based antibiotic delivery methods often employed for local antibiotic delivery in the treatment of these infections.

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

    Science.gov (United States)

    Baharoglu, Zeynep; Babosan, Anamaria; Mazel, Didier

    2014-02-01

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

  17. Forgotten antibiotics

    DEFF Research Database (Denmark)

    Pulcini, Céline; Bush, Karen; Craig, William A;

    2012-01-01

    In view of the alarming spread of antimicrobial resistance in the absence of new antibiotics, this study aimed at assessing the availability of potentially useful older antibiotics. A survey was performed in 38 countries among experts including hospital pharmacists, microbiologists, and infectious...... disease specialists in Europe, the United States, Canada, and Australia. An international expert panel selected systemic antibacterial drugs for their potential to treat infections caused by resistant bacteria or their unique value for specific criteria. Twenty-two of the 33 selected antibiotics were...... available in fewer than 20 of 38 countries. Economic motives were the major cause for discontinuation of marketing of these antibiotics. Fourteen of 33 antibiotics are potentially active against either resistant Gram-positive or Gram-negative bacteria. Urgent measures are then needed to ensure better...

  18. An in vitro study on the effects of nisin on the antibacterial activities of 18 antibiotics against Enterococcus faecalis.

    Science.gov (United States)

    Tong, Zhongchun; Zhang, Yuejiao; Ling, Junqi; Ma, Jinglei; Huang, Lijia; Zhang, Luodan

    2014-01-01

    Enterococcus faecalis rank among the leading causes of nosocomial infections worldwide and possesses both intrinsic and acquired resistance to a variety of antibiotics. Development of new antibiotics is limited, and pathogens continually generate new antibiotic resistance. Many researchers aim to identify strategies to effectively kill this drug-resistant pathogen. Here, we evaluated the effect of the antimicrobial peptide nisin on the antibacterial activities of 18 antibiotics against E. faecalis. The MIC and MBC results showed that the antibacterial activities of 18 antibiotics against E. faecalis OG1RF, ATCC 29212, and strain E were significantly improved in the presence of 200 U/ml nisin. Statistically significant differences were observed between the results with and without 200 U/ml nisin at the same concentrations of penicillin or chloramphenicol (pnisin and penicillin or chloramphenicol had a synergetic effect against the three tested E. faecalis strains. The transmission electron microscope images showed that E. faecalis was not obviously destroyed by penicillin or chloramphenicol alone but was severely disrupted by either antibiotic in combination with nisin. Furthermore, assessing biofilms by a confocal laser scanning microscope showed that penicillin, ciprofloxacin, and chloramphenicol all showed stronger antibiofilm actions in combination with nisin than when these antibiotics were administered alone. Therefore, nisin can significantly improve the antibacterial and antibiofilm activities of many antibiotics, and certain antibiotics in combination with nisin have considerable potential for use as inhibitors of this drug-resistant pathogen.

  19. An in vitro study on the effects of nisin on the antibacterial activities of 18 antibiotics against Enterococcus faecalis.

    Directory of Open Access Journals (Sweden)

    Zhongchun Tong

    Full Text Available Enterococcus faecalis rank among the leading causes of nosocomial infections worldwide and possesses both intrinsic and acquired resistance to a variety of antibiotics. Development of new antibiotics is limited, and pathogens continually generate new antibiotic resistance. Many researchers aim to identify strategies to effectively kill this drug-resistant pathogen. Here, we evaluated the effect of the antimicrobial peptide nisin on the antibacterial activities of 18 antibiotics against E. faecalis. The MIC and MBC results showed that the antibacterial activities of 18 antibiotics against E. faecalis OG1RF, ATCC 29212, and strain E were significantly improved in the presence of 200 U/ml nisin. Statistically significant differences were observed between the results with and without 200 U/ml nisin at the same concentrations of penicillin or chloramphenicol (p<0.05. The checkerboard assay showed that the combination of nisin and penicillin or chloramphenicol had a synergetic effect against the three tested E. faecalis strains. The transmission electron microscope images showed that E. faecalis was not obviously destroyed by penicillin or chloramphenicol alone but was severely disrupted by either antibiotic in combination with nisin. Furthermore, assessing biofilms by a confocal laser scanning microscope showed that penicillin, ciprofloxacin, and chloramphenicol all showed stronger antibiofilm actions in combination with nisin than when these antibiotics were administered alone. Therefore, nisin can significantly improve the antibacterial and antibiofilm activities of many antibiotics, and certain antibiotics in combination with nisin have considerable potential for use as inhibitors of this drug-resistant pathogen.

  20. 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. PMID:27547203

  1. 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. PMID:27547203

  2. Appearance of amikacin and tobramycin resistance due to 4'-aminoglycoside nucleotidyltransferase [ANT(4')-II] in gram-negative pathogens.

    OpenAIRE

    Jacoby, G A; Blaser, M J; Santanam, P; Hächler, H; Kayser, F H; Hare, R S; Miller, G. H.

    1990-01-01

    Following the use of amikacin as the principal aminoglycoside at a Denver hospital, amikacin resistance appeared first in Pseudomonas aeruginosa and then in Escherichia coli, Klebsiella pneumoniae, and other enteric organisms from debilitated and compromised patients who had spent time in intensive care units and who had been treated with multiple antibiotics, usually including amikacin. In a P. aeruginosa isolate, resistance to amikacin and tobramycin was transferable by the IncP-2 plasmid p...

  3. Synergistic anti-Campylobacter jejuni activity of fluoroquinolone and macrolide antibiotics with phenolic compounds

    Directory of Open Access Journals (Sweden)

    Euna eOh

    2015-10-01

    Full Text Available The increasing resistance of Campylobacter to clinically-important antibiotics, such as fluoroquinolones and macrolides, is a serious public health problem. The objective of this study is to investigate synergistic anti-Campylobacter jejuni activity of fluoroquinolones and macrolides in combination with phenolic compounds. Synergistic antimicrobial activity was measured by performing a checkerboard assay with ciprofloxacin and erythromycin in the presence of 21 phenolic compounds. Membrane permeability changes in C. jejuni by phenolic compounds were determined by measuring the level of intracellular uptake of 1-N-phenylnaphthylamine (NPN. Antibiotic accumulation assays were performed to evaluate the level of ciprofloxacin accumulation in C. jejuni. Six phenolic compounds, including p-coumaric acid, sinapic acid, caffeic acid, vanillic acid, gallic acid, and taxifolin, significantly increased the susceptibility to ciprofloxacin and erythromycin in several human and poultry isolates. The synergistic antimicrobial effect was also observed in ciprofloxacin- and erythromycin-resistant C. jejuni strains. The phenolic compounds also substantially increased membrane permeability and antibiotic accumulation in C. jejuni. Interestingly, some phenolic compounds, such as gallic acid and taxifolin, significantly reduced the expression of the CmeABC multidrug efflux pump. Phenolic compounds increased the NPN accumulation in the cmeB mutant, indicating phenolic compounds may affect the membrane permeability. In this study, we successfully demonstrated that combinational treatment of C. jejuni with antibiotics and phenolic compounds synergistically inhibits C. jejuni by impacting both antimicrobial influx and efflux.

  4. Deficient autolytic enzyme activity in antibiotic-tolerant lactobacilli.

    OpenAIRE

    Kim, K. S.; Morrison, J O; Bayer, A S

    1982-01-01

    To define the mechanism(s) of penicillin tolerance in lactobacilli, one nontolerant and two tolerant strains were examined for autolytic enzyme activity. When incubated with 14C-labeled cell wall preparations, autolysin extracts of tolerant lactobacilli released significantly less radioactivity than did extracts of nontolerant lactobacilli (p less than 0.02). These differences in the release of radioactivity by nontolerant and tolerant strains were maximal during the logarithmic growth phase....

  5. Intracellular activity of antibiotics against Staphylococcus aureus in a mouse peritonitis model.

    Science.gov (United States)

    Sandberg, Anne; Hessler, Jonas H R; Skov, Robert L; Blom, Jens; Frimodt-Møller, Niels

    2009-05-01

    Antibiotic treatment of Staphylococcus aureus infections is often problematic due to the slow response to therapy and the high frequency of infection recurrence. The intracellular persistence of staphylococci has been recognized and could offer a good explanation for these treatment difficulties. Knowledge of the interplay between intracellular antibiotic activity and the overall outcome of infection is therefore important. Several intracellular in vitro models have been developed, but few experimental animal models have been published. The mouse peritonitis/sepsis model was used as the basic in vivo model exploring a quantitative ex vivo extra- and intracellular differentiation assay. The intracellular presence of S. aureus was documented by electron microscopy. Five antibiotics, dicloxacillin, cefuroxime, gentamicin, azithromycin, and rifampin (rifampicin), were tested in the new in vivo model; and the model was able to distinguish between their extra- and intracellular effects. The intracellular effects of the five antibiotics could be ranked as follows as the mean change in the log(10) number of CFU/ml (Delta log(10) CFU/ml) between treated and untreated mice after 4 h of treatment: dicloxacillin (3.70 Delta log(10) CFU/ml) > cefuroxime (3.56 Delta log(10) CFU/ml) > rifampin (1.86 Delta log(10) CFU/ml) > gentamicin (0.61 Delta log(10) CFU/ml) > azithromycin (0.21 Delta log(10) CFU/ml). We could also show that the important factors during testing of intracellular activity in vivo are the size, number, and frequency of doses; the time of exposure; and the timing between the start of infection and treatment. A poor correlation between the intracellular accumulation of the antibiotics and the actual intracellular effect was found. This stresses the importance of performing experimental studies, like those with the new in vivo model described here, to measure actual intracellular activity instead of making predictions based on cellular pharmacokinetic and MICs. PMID

  6. [Comparative urinary bactericidal activity of oral antibiotics against gram-positive pathogens].

    Science.gov (United States)

    Bedenić, Branka; Budimir, Ana; Gverić, Ana; Plecko, Vanda; Vranes, Jasmina; Bubonja-Sonje, Marina; Kalenić, Smilja

    2012-01-01

    In routine bacteriological laboratories the antibacterial activity of antibiotics is determined by in vitro testing, usually by disk-diffusion test. However, in vitro testing does not always reflect antibacterial efficiency of antibiotics in vivo. In this investigation, the urine samples obtained in a single oral dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant Gram-positive urinary tract pathogens. Urinary bactericidal activity of linezolid had been previously compared with ciprofloxacin but not with other oral antibiotics such as beta-lactams. Linezolid showed satisfactory urinary bactericidal titres throughout the whole testing period against all Gram-positive cocci. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against staphylococci, but their activity against enterococci was weaker. According to the results of ex-vivo testing amoxycillin could be recommended only for infections caused by E. faecalis. Amoxycillin combined with clavulanic acid can be considered as a therapeutic option for infections caused by S. saprophyticus and E. faecalis. Older cephalosporins had high titres only against S. saprophyticus. Their drawback is a short elimination half-time in urine resulting in rapid decrease of urinary bactericidal titers during dosing interval. Furthermore, they do not show activity against enterococci due to their intrinsic resistance to cephalosporins. PMID:22930932

  7. 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.

  8. Dissecting the cosubstrate structure requirements of the Staphylococcus aureus aminoglycoside resistance enzyme ANT(4').

    Science.gov (United States)

    Porter, Vanessa R; Green, Keith D; Zolova, Olga E; Houghton, Jacob L; Garneau-Tsodikova, Sylvie

    2010-12-01

    Aminoglycosides are important antibiotics used against a wide range of pathogens. As a mechanism of defense, bacteria have evolved enzymes able to inactivate these drugs by regio-selectively adding a variety of functionalities (acetyl, phospho, and nucelotidyl groups) to their scaffolds. The aminoglycoside nucleotidyltransferase ANT(4') is one of the most prevalent and unique modifying-enzymes. Here, by TLC, HRMS, and colorimetric assays, we demonstrate that the resistance enzyme ANT(4') from Staphylococcus aureus is highly substrate and cosubstrate promiscuous. We show that deoxy-ribonucleotide triphosphates (dNTPs) are better cosubstrates than NTPs. We demonstrate that the position of the triphosphate group (5' and not 3') on the ribose/deoxyribose ring is important for recognition by ANT(4'), and that NTPs with larger substituents at the 3'-position of the ribose ring are not cosubstrates for ANT(4'). We confirm that for all aminoglycosides tested, the respective nucleotidylated products are completely inactive. These results provide valuable insights into the development of strategies to combat the ever-growing bacterial resistance problem. PMID:21040710

  9. Antibacterial Activity of Propolis Ethanol Extract against Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Maryam Mohammadi-Sichani

    2014-03-01

    Full Text Available Background: Burn wound is a suitable site for incidence of resistant infections; thus, the research for finding effective drugs against this infection is necessary. The purpose of this study was to determine antibacterial activity of Isfahan bee propolis extracts against beta-lactamase producing bacteria isolated from burn wound infections. Materials and Methods: Ethanol extract of Isfahan bee propolis was prepared by 28 g of propolis in 100 ml of 70% ethanol. Antibacterial activity of ethanol extracts were evaluated against beta-lactamase producing bacteria (Staphylococcus aureus and Pseudomonas aeruginosa isolated of burn wound infection by well diffusion method. Broth serial dilution method was used to determine MBC of extract. Beta-lactamase production of isolates was detected by iodometric test, imipenem-EDTA combined disk test and imipenem-EDTA double-disk synergy test. Results: Ethanol extract of propolis was found to be the most effective against S. aureus strains (inhibition zone=17.66±0.47 mm than P. aeruginosa strains (inhibition zone=7 mm. The MIC and MBC values of the extracts against S. aureus strains were 0.0143 and 0.0286 mg/ml and these values against P. aeruginosa strains were 0.75 and 1.5 mg/ml, respectively. Among the S. aureus clinical isolates, all of strains produced beta-lactamase. Imipenem-EDTA double-disk synergy test showed that only one clinical isolate of P. aeruginosa was metallo-beta-lactamase positive. Conclusion: This study demonstrated that ethanol extract of Isfahan bee propolis is mainly active against S. aureus and it is effective on P. aeruginosa at higher concentration. Ethanol extract of propolis did not inhibit production of beta-lactamase enzyme in tested bacteria.

  10. Gramicidin A Mutants with Antibiotic Activity against Both Gram-Positive and Gram-Negative Bacteria.

    Science.gov (United States)

    Zerfas, Breanna L; Joo, Yechaan; Gao, Jianmin

    2016-03-17

    Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic-resistant bacteria. One promising example of this is gramicidin A (gA). In its wild-type sequence, gA is active by permeating the plasma membrane of Gram-positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa. PMID:26918268

  11. Antibacterial activities of silver nanoparticles and antibiotic-adsorbed silver nanoparticles against biorecycling microbes.

    Science.gov (United States)

    Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

    2014-09-20

    Silver nanoparticles have a huge share in nanotechnology based products used in clinical and hygiene products. Silver nanoparticles leaching from these medical and domestic products will eventually enter terrestrial ecosystems and will interact with the microbes present in the land and water. These interactions could be a threat to biorecycling microbes present in the Earth's crust. The antimicrobial action towards biorecycling microbes by leached silver nanoparticles from medical waste could be many times greater compared to that of silver nanoparticles leached from other domestic products, since medical products may contain traditional antibiotics along with silver nanoparticles. In the present article, we have evaluated the antimicrobial activities of as-synthesized silver nanoparticles, antibiotics - tetracycline and kanamycin, and antibiotic-adsorbed silver nanoparticles. The antimicrobial action of silver nanoparticles with adsorbed antibiotics is 33-100% more profound against the biorecycling microbes B. subtilis and Pseudomonas compared to the antibacterial action of silver nanoparticles of the same concentration. This study indicates that there is an immediate and urgent need for well-defined protocols for environmental exposure to silver nanoparticles, as the use of silver nanoparticles in nanotechnology based products is poorly restricted.

  12. Epilobi Hirsuti Herba Extracts Influence the In Vitro Activity of Common Antibiotics on Standard Bacteria

    Directory of Open Access Journals (Sweden)

    Pirvu Lucia

    2016-03-01

    Full Text Available Epilobium genus has been confirmed as an effective source of natural antimicrobials. However, the influence of Epilobi hirsuti herba derived products on usual antibiotics activity has not been studied. In this study, several standardized Epilobi hirsuti herba extracts (EHE were evaluated in order to asses their potential effects on usual antibiotics tested on standard Gram-positive and Gram-negative bacterial strains in vitro. The results emphasized that the bacterial strains ranged from sensitive (MIC values between 50–200 μg GAE mL-1 (S. epidermidis ATCC 12228 to very resistant (E. coli strains, E. faecalis ATCC 29212 being practically immune to EHE. In terms of synergistic interaction, Tetracycline and Ampicillin combinations lead to the most important stimulatory effects, the diameters of the inhibition zone being even 60% bigger compared to the antibiotic alone. Synergistic effects between myricetin(galloyl derivates and Tetracycline were also revealed on P. aeruginosa and E. coli strains. Together, it clearly demonstrated not only EHE’s own antimicrobial properties, but also their capacity to influence the antimicrobial potency of some common antibiotics. These results could be useful for the area of herbal medicines and as potential candidates in managing microbial resistance, but also for physicians and pharmacists using combined antibacterial therapy.

  13. Antibacterial Activity and Antibiotic-Enhancing Effects of Honeybee Venom against Methicillin-Resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Sang Mi Han

    2016-01-01

    Full Text Available Methicillin-resistant Staphylococcus aureus (MRSA, along with other antibiotic resistant bacteria, has become a significant social and clinical problem. There is thus an urgent need to develop naturally bioactive compounds as alternatives to the few antibiotics that remain effective. Here we assessed the in vitro activities of bee venom (BV, alone or in combination with ampicillin, penicillin, gentamicin or vancomycin, on growth of MRSA strains. The antimicrobial activity of BV against MRSA strains was investigated using minimum inhibitory concentrations (MIC, minimum bactericidal concentrations (MBC and a time-kill assay. Expression of atl which encodes murein hydrolase, a peptidoglycan-degrading enzyme involved in cell separation, was measured by reverse transcription-polymerase chain reaction. The MICs of BV were 0.085 µg/mL and 0.11 µg/mL against MRSA CCARM 3366 and MRSA CCARM 3708, respectively. The MBC of BV against MRSA 3366 was 0.106 µg/mL and that against MRSA 3708 was 0.14 µg/mL. The bactericidal activity of BV corresponded to a decrease of at least 3 log CFU/g cells. The combination of BV with ampicillin or penicillin yielded an inhibitory concentration index ranging from 0.631 to 1.002, indicating a partial and indifferent synergistic effect. Compared to ampicillin or penicillin, both MRSA strains were more susceptible to the combination of BV with gentamicin or vancomycin. The expression of atl gene was increased in MRSA 3366 treated with BV. These results suggest that BV exhibited antibacterial activity and antibiotic-enhancing effects against MRSA strains. The atl gene was increased in MRSA exposed to BV, suggesting that cell division was interrupted. BV warrants further investigation as a natural antimicrobial agent and synergist of antibiotic activity.

  14. Antibacterial Activity and Antibiotic-Enhancing Effects of Honeybee Venom against Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Han, Sang Mi; Kim, Joung Min; Hong, In Pyo; Woo, Soon Ok; Kim, Se Gun; Jang, He Rye; Pak, Sok Cheon

    2016-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA), along with other antibiotic resistant bacteria, has become a significant social and clinical problem. There is thus an urgent need to develop naturally bioactive compounds as alternatives to the few antibiotics that remain effective. Here we assessed the in vitro activities of bee venom (BV), alone or in combination with ampicillin, penicillin, gentamicin or vancomycin, on growth of MRSA strains. The antimicrobial activity of BV against MRSA strains was investigated using minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC) and a time-kill assay. Expression of atl which encodes murein hydrolase, a peptidoglycan-degrading enzyme involved in cell separation, was measured by reverse transcription-polymerase chain reaction. The MICs of BV were 0.085 µg/mL and 0.11 µg/mL against MRSA CCARM 3366 and MRSA CCARM 3708, respectively. The MBC of BV against MRSA 3366 was 0.106 µg/mL and that against MRSA 3708 was 0.14 µg/mL. The bactericidal activity of BV corresponded to a decrease of at least 3 log CFU/g cells. The combination of BV with ampicillin or penicillin yielded an inhibitory concentration index ranging from 0.631 to 1.002, indicating a partial and indifferent synergistic effect. Compared to ampicillin or penicillin, both MRSA strains were more susceptible to the combination of BV with gentamicin or vancomycin. The expression of atl gene was increased in MRSA 3366 treated with BV. These results suggest that BV exhibited antibacterial activity and antibiotic-enhancing effects against MRSA strains. The atl gene was increased in MRSA exposed to BV, suggesting that cell division was interrupted. BV warrants further investigation as a natural antimicrobial agent and synergist of antibiotic activity. PMID:26771592

  15. Exogenous pulmonary surfactant as a drug delivering agent: influence of antibiotics on surfactant activity.

    OpenAIRE

    van 't Veen, A; Gommers, D.; Mouton, J. W.; Kluytmans, J.A.; Krijt, E. J.; Lachmann, B.

    1996-01-01

    1. It has been proposed to use exogenous pulmonary surfactant as a drug delivery system for antibiotics to the alveolar compartment of the lung. Little, however, is known about interactions between pulmonary surfactant and antimicrobial agents. This study investigated the activity of a bovine pulmonary surfactant after mixture with amphotericin B, amoxicillin, ceftazidime, pentamidine or tobramycin. 2. Surfactant (1 mg ml-1 in vitro and 40 mg ml-1 in vivo) was mixed with 0.375 mg ml-1 amphote...

  16. Penicillin-Bound Polyacrylate Nanoparticles: Restoring the Activity of β-Lactam Antibiotics Against MRSA

    OpenAIRE

    Turos, Edward; Reddy, G. Suresh Kumar; Greenhalgh, Kerriann; Ramaraju, Praveen; Abeylath, Sampath C.; Jang, Seyoung; Dickey, Sonja; Lim, Daniel V

    2007-01-01

    This report describes the preparation of antibacterially-active emulsified polyacrylate nanoparticles in which a penicillin antibiotic is covalently conjugated onto the polymeric framework. These nanoparticles were prepared in water by emulsion polymerization of an acrylated penicillin analogue pre-dissolved in a 7:3 (w:w) mixture of butyl acrylate and styrene in the presence of sodium dodecyl sulfate (surfactant) and potassium persulfate (radical initiator). Dynamic light scattering analysis...

  17. Synthesis and biological activity of new quinoxaline antibiotics of echinomycin analogues.

    Science.gov (United States)

    Kim, Yun Bong; Kim, Yong Hae; Park, Ju Youn; Kim, Soo Kie

    2004-01-19

    Novel quinoxaline antibiotics having the methylenedithioether bridge as an analogue of echinomycin have been synthesized by insertion of methylene moiety between -S-S- bond. The compound 1a shows remarkable cytotoxicities against human tumor various cell lines, and is active VRE (vancomycin-resistant enterococci) within MIC range 0.5-8 microg/mL. According to the eukaryotic or prokaryotic data, 1a might be a first analogue to replace echinomycin.

  18. Activity and interactions of antibiotic and phytochemical combinations against Pseudomonas aeruginosa in vitro

    Directory of Open Access Journals (Sweden)

    Premkumar Jayaraman, Meena K Sakharkar, Chu Sing Lim, Thean Hock Tang, Kishore R. Sakharkar

    2010-01-01

    Full Text Available In this study the in vitro activities of seven antibiotics (ciprofloxacin, ceftazidime, tetracycline, trimethoprim, sulfamethoxazole, polymyxin B and piperacillin and six phytochemicals (protocatechuic acid, gallic acid, ellagic acid, rutin, berberine and myricetin against five P. aeruginosa isolates, alone and in combination are evaluated. All the phytochemicals under investigation demonstrate potential inhibitory activity against P. aeruginosa. The combinations of sulfamethoxazole plus protocatechuic acid, sulfamethoxazole plus ellagic acid, sulfamethoxazole plus gallic acid and tetracycline plus gallic acid show synergistic mode of interaction. However, the combinations of sulfamethoxazole plus myricetin shows synergism for three strains (PA01, DB5218 and DR3062. The synergistic combinations are further evaluated for their bactericidal activity against P. aeruginosa ATCC strain using time-kill method. Sub-inhibitory dose responses of antibiotics and phytochemicals individually and in combination are presented along with their interaction network to suggest on the mechanism of action and potential targets for the phytochemicals under investigation. The identified synergistic combinations can be of potent therapeutic value against P. aeruginosa infections. These findings have potential implications in delaying the development of resistance as the antibacterial effect is achieved with lower concentrations of both drugs (antibiotics and phytochemicals.

  19. Investigations into the Antibacterial Activity of the Silver-Based Antibiotic Drug Candidate SBC3

    Directory of Open Access Journals (Sweden)

    Matthias Tacke

    2012-11-01

    Full Text Available The synthesis of N-heterocyclic carbene (NHC silver(I acetate complexes with varying lipophilic benzyl-substituents at the 1 and 3 positions starting from 4,5-diphenylimidazole, opened a new class of antibiotic drug candidates. These NHC-silver(I acetate derivatives exhibit interesting structural motifs in the solid state and proved to be soluble and stable in biological media. The leading candidate, SBC3, which was known to exhibit good antibacterial activity in preliminary Kirby-Bauer tests, was tested quantitatively using minimum inhibitory concentrations. NHC-silver(I acetate complexes were found to have MIC values ranging from 20 to 3.13 μg/mL for a variety of Gram-positive, Gram-negative and mycobacteria tested. These values represent good antibiotic activities against potential pathogens when compared to clinically approved antibiotics. Most striking is the fact that SBC3 is active against methicillin-resistant Staphylococcus aureus with a MIC value of 12.5 μg/mL.

  20. Induction kinetics of the Staphylococcus aureus cell wall stress stimulon in response to different cell wall active antibiotics

    Directory of Open Access Journals (Sweden)

    Berger-Bächi Brigitte

    2011-01-01

    Full Text Available Abstract Background Staphylococcus aureus activates a protective cell wall stress stimulon (CWSS in response to the inhibition of cell wall synthesis or cell envelope damage caused by several structurally and functionally different antibiotics. CWSS induction is coordinated by the VraSR two-component system, which senses an unknown signal triggered by diverse cell wall active agents. Results We have constructed a highly sensitive luciferase reporter gene system, using the promoter of sas016 (S. aureus N315, which detects very subtle differences in expression as well as measuring > 4 log-fold changes in CWSS activity, to compare the concentration dependence of CWSS induction kinetics of antibiotics with different cell envelope targets. We compared the effects of subinhibitory up to suprainhibitory concentrations of fosfomycin, D-cycloserine, tunicamycin, bacitracin, flavomycin, vancomycin, teicoplanin, oxacillin, lysostaphin and daptomycin. Induction kinetics were both strongly antibiotic- and concentration-dependent. Most antibiotics triggered an immediate response with induction beginning within 10 min, except for tunicamycin, D-cycloserine and fosfomycin which showed lags of up to one generation before induction commenced. Induction characteristics, such as the rate of CWSS induction once initiated and maximal induction reached, were strongly antibiotic dependent. We observed a clear correlation between the inhibitory effects of specific antibiotic concentrations on growth and corresponding increases in CWSS induction kinetics. Inactivation of VraR increased susceptibility to the antibiotics tested from 2- to 16-fold, with the exceptions of oxacillin and D-cycloserine, where no differences were detected in the methicillin susceptible S. aureus strain background analysed. There was no apparent correlation between the induction capacity of the various antibiotics and the relative importance of the CWSS for the corresponding resistance phenotypes

  1. Degradation of antibiotic activity during UV/H2O2 advanced oxidation and photolysis in wastewater effluent.

    Science.gov (United States)

    Keen, Olya S; Linden, Karl G

    2013-11-19

    Trace levels of antibiotics in treated wastewater effluents may present a human health risk due to the rise of antibacterial activity in the downstream environments. Advanced oxidation has a potential to become an effective treatment technology for transforming trace antibiotics in wastewater effluents, but residual or newly generated antibacterial properties of transformation products are a concern. This study demonstrates the effect of UV photolysis and UV/H2O2 advanced oxidation on transformation of 6 antibiotics, each a representative of a different structural class, in pure water and in two different effluents and reports new or confirmatory photolysis quantum yields and hydroxyl radical rate constants. The decay of the parent compound was monitored with HPLC/ITMS, and the corresponding changes in antibacterial activity were measured using bacterial inhibition assays. No antibacterially active products were observed following treatment for four of the six antibiotics (clindamycin, ciprofloxacin, penicillin-G, and trimethoprim). The remaining two antibiotics (erythromycin and doxycycline) showed some intermediates with antibacterial activity at low treatment doses. The antibacterially active products lost activity as the UV dose increased past 500 mJ/cm(2). Active products were observed only in wastewater effluents and not in pure water, suggesting that complex secondary reactions controlled by the composition of the matrix were responsible for their formation. This outcome emphasizes the importance of bench-scale experiments in realistic water matrices. Most importantly, the results indicate that photosensitized processes during high dose wastewater disinfection may be creating antibacterially active transformation products from some common antibiotics.

  2. Efflux Pump Blockers in Gram-Negative Bacteria: The New Generation of Hydantoin Based-Modulators to Improve Antibiotic Activity.

    Science.gov (United States)

    Otręebska-Machaj, Ewa; Chevalier, Jacqueline; Handzlik, Jadwiga; Szymańska, Ewa; Schabikowski, Jakub; Boyer, Gérard; Bolla, Jean-Michel; Kieć-Kononowicz, Katarzyna; Pagès, Jean-Marie; Alibert, Sandrine

    2016-01-01

    Multidrug resistant (MDR) bacteria are an increasing health problem with the shortage of new active antibiotic agents. Among effective mechanisms that contribute to the spread of MDR Gram-negative bacteria are drug efflux pumps that expel clinically important antibiotic classes out of the cell. Drug pumps are attractive targets to restore the susceptibility toward the expelled antibiotics by impairing their efflux activity. Arylhydantoin derivatives were investigated for their potentiation of activities of selected antibiotics described as efflux substrates in Enterobacter aerogenes expressing or not AcrAB pump. Several compounds increased the bacterial susceptibility toward nalidixic acid, chloramphenicol and sparfloxacin and were further pharmacomodulated to obtain a better activity against the AcrAB producing bacteria. PMID:27199950

  3. Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

    Directory of Open Access Journals (Sweden)

    Chandrasekaran, R.

    2011-01-01

    Full Text Available Solvent extracts of native purple non-sulfur bacterial (PNSB isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the antagonistic extracts from Rba. sphaeroides could be used as an effective antibiotic in controlling Vibrio spp., in aquaculture systems.

  4. Sustainable Activated Carbons from Agricultural Residues Dedicated to Antibiotic Removal by Adsorption

    Institute of Scientific and Technical Information of China (English)

    Jonatan Torres-Perez; Claire Gerente; Yves Andres

    2012-01-01

    The. objectives.of this study are to convert at laboratory s.cale agric.ultural residues into activated carbons (AC) with specific properties, to characterize them and to test them in adsorption reactor for tetracycline removal, a common antibiotic. Two new ACs were produced by direct activation with steam from beet pulp (BP-H2O) and peanut hu_lls (PH-H2O) in environmental friendly conditions BP-H2O and PH-H2Opresentcarbon content rangedcarbons with different intrinsic properties.

  5. On the use of antibiotics to reduce rhizoplane microbial populations in root physiology and ecology investigations

    Science.gov (United States)

    Smart, D. R.; Ferro, A.; Ritchie, K.; Bugbee, B. G.

    1995-01-01

    No straightforward method exists for separating the proportion of ion exchange and respiration due to rhizoplane microbial organisms from that of root ion exchange and respiration. We examined several antibiotics that might be used for the temporary elimination of rhizoplane bacteria from hydroponically grown wheat roots (Triticum aestivum cv. Veery 10). Each antibiotic was tested for herbicidal activity and plate counts were used to enumerate bacteria and evaluate antibiotic kinetics. Only lactam antibiotics (penicillins and cephalosporins) did not reduce wheat growth rates. Aminoglycosides, the pyrimidine trimethoprim, colistin and rifampicin reduced growth rates substantially. Antibiotics acted slowly, with maximum reductions in rhizoplane bacteria occurring after more than 48 h of exposure. Combinations of nonphytotoxic antibiotics reduced platable rhizoplane bacteria by as much as 98%; however, this was generally a reduction from about 10(9) to 10(6) colony forming units per gram of dry root mass, so that many viable bacteria remained on root surfaces. We present evidence which suggests that insufficient bacterial biomass exists on root surfaces of nonstressed plants grown under well-aerated conditions to quantitatively interfere with root nitrogen absorption measurements.

  6. Antibiotic susceptibility and antimicrobial activity of autochthonous starter cultures as safety parameters for fresh cheese production

    Directory of Open Access Journals (Sweden)

    Dora Bučan

    2013-11-01

    Full Text Available The antibiotic susceptibility and antimicrobial activity, as food safety parameters important for application of autochthonous lactic acid bacteria (LAB, that previously satisfied technological criteria for functional starter cultures in fresh cheese production were examined. Soluble whole cell protein patterns of autochthonous LAB strains from fresh cheese, obtained by SDS-PAGE, revealed the presence of two predominant strains, which were identified as Lactobacillus fermentum A8 and Enterococcus faecium A7. These strains were not resistant and shown susceptibility to antibiotics: ampicillin, bacitracin, penicillin G, azithromycin, chloramphenicol, clarithromycin, clindamycin, spiramycin, tetracycline, streptomycin, neomycin, gentamicin, erythromycin, rifampicin and novobiocin. Lb. fermentum A8 strain displayed phenotypic resistance to vancomycin, but this resistance is intrinsic, not transferable and it is acceptable from the safety aspect. The capacity of Lb. fermentum A8 and Ec. faecium A7 to inhibit growth of test-microorganisms Listeria monocytogenes ATCC 11911, Escherichia coli 3014, Salmonella enterica serovar Typhimurium FP1 and Staphylococcus aureus 3048, was also analysed. According to obtained results, Lb. fermentum A8 and Ec. faecium A7 are safe from the aspect of spreading antibiotic resistance and could be useful as bioprotective cultures that inhibit common bacterial food contaminants, including L. monocytogenes.

  7. Isolation, Phylogenetic Analysis and Antibiotic Activity Screening of Red Sea Sponge-Associated Actinobacteria

    KAUST Repository

    Yang, Chen

    2013-06-01

    Infectious disease has always been and will continue to be a heavy burden on human society worldwide. Terrestrial actinobacteria, notable as a source of antibiotics, have been well investigated in the past. In constrast, marine actinobacteria, especially sponge-associated species, have received much less attention and isolates are sparse. With the aim of studying and discovering novel marine actinobacteria, 11 different species of sponges were collected from the Central Red Sea in Saudi Arabia and cultured with three different types of media. 16S rRNA gene-sequencing revealed that among all 75 isolated bacterial strains 13 belonged to the order actinomycetales. These 13 actinomycetes fall into four different families and can be assigned to six different genera. Antibiotic activity tests using disc diffusion assay were performed against Gram-positive bacteria (Bacillus sp.), Gram-negative bacteria (Escherichia coli), fungi (Fusarium sp.) and West Nile virus NS3 protease. Nine strains presented different level of bioactivity against these pathogens. These findings provide evidence that actinomycetes are presented in marine sponges and that they have the potential to be good candidates in the search for new effective antibiotic, antifungal, and antiviral compounds.

  8. ANTIBACTERIAL ACTIVITY OF TRADITIONAL HERBS AND STANDARD ANTIBIOTICS AGAINST POULTRY ASSOCIATED PSEUDOMONAS AERUGINOSA

    Directory of Open Access Journals (Sweden)

    Affia Rafique

    2012-10-01

    Full Text Available Present study aims to access the antibacterial activity of medicinal plants and antibiotics against poultry associated Pseudomonas aeruginosa. P. aeruginosa is the most widespread avian pathogen and it produces a range of toxins and enzymes that may contribute to pathogenicity. P. aeruginosa was isolated from the chicken liver and identified through biochemical methods. The antibacterial activity of extracts of medicinal herbs and various antibiotics were analyzed against P. aeruginosa through agar disc diffusion method. P. aeruginosa was susceptible against Norfloxacin, Chloramphenicol, Streptomycin, Gentamicin, Tobramycin, and Ciprofloxacin. Whereas, moderately susceptible in case of Oxytetracycline, Neomycin, Lincomycin, and Sulfomethoxyzol. It was also analyzed that Ampicillin, Tetracycline, Penicillin G and Trimethoprim had no effect. Among the plants tested C. zylanicum, C. cyminum, T. ammi, S. aromaticum and green part of M. charantia were most active. The maximum antibacterial activity was calculated by the extracts of isoamylalcohol of C. zylanicum, C. cyminum, T. ammi, S. aromaticum, and ethanolic and methanol extract of green part of M. charantia against P. aeruginosa. This study indicated that these medicinal plants could be the potential source for antimicrobial agents. Hence, these medicinal plants can be further subjected to isolation of the therapeutic antimicrobials and further pharmacological evaluation.

  9. Screening a Mediterranean Sponge Axinella verrucosa For Antibacterial Activity in Comparison to Some Antibiotics

    Directory of Open Access Journals (Sweden)

    Alma Shabbar

    2013-03-01

    Full Text Available The antibacterial effect of crude extract of marine sponge Axinella verrucosa at room temperature against seven nosocomial bacteria and one fungal isolates including, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter septicus and Proteus vulgaris, Acinetobacter meningitis, Klebsiella pneumonia, E. coli and the fungal pathogen Candida albicans were studied by Kirby-Bauer disc diffusion assay and, the findings of antibacterial activity of crude methanolic extract sponge A. verrucosa were compared to the efficiency of some marketed antibiotics that were tested against the same bacteria at given concentrations. In result, it was found that MeOH crude extract of Axinella verrucosa is effective against Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter septicus and Proteus vulgaris and except for its ineffectiveness against Acinetobacter meningitis, Klebsiella pneumonia, E. coli and the fungal pathogen Candida albicans. It was more active than Azithromycin and Gentamicin Against Proteus vulgaris and more efficient than ciprofloxacin against Acinetobacter septicus. Hexane and Ethyl acetate crude extracts derived from A. verrucosa revealed no activity against all bacterial and fungal pathogen. Sponge Axinella verrucosa remains an interesting source of new antibacterial metabolites with better activity than some antibiotics.

  10. Isolation, purification and identification of three peptaibols from Trichoderma koningii with antibiotic activity against Ralstonia solancearum

    Institute of Scientific and Technical Information of China (English)

    SHEN Qing-tao; CHEN Xiu-lan; SUN Cai-yun; ZHANG Yu-zhong

    2004-01-01

    @@ The use of microorganisms for biological purposes has become an effective alternative to control plant pathogens. Trichoderma koningii Smf2 was chosen from eight Trichoderma strains for its thermostatic metabolites with antibiotic activity against Ralstonia solancearum Smith. Exclusion chromatography (LH20) was used twice to partially purify targeted metabolites combined with biological test. LC/ESI-MS, a powerful tool for rapid identification and sequence determination of peptides, identified these metabolites as three peptaibols named Trichokonin Ⅵ, Ⅶ and Ⅷ, and their sequences were confirmed with NMR.

  11. Frequency of Aminoglycoside-Resistance Genes in Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Hospitalized Patients

    Science.gov (United States)

    Mahdiyoun, Seyed Mohsen; Kazemian, Hossein; Ahanjan, Mohammad; Houri, Hamidreza; Goudarzi, Mehdi

    2016-01-01

    Background Staphylococcus aureus is one of the most important causative agents in community- and hospital-acquired infections. Aminoglycosides are powerful bactericidal drugs that are often used in combination with beta-lactams or glycopeptides to treat staphylococcal infections. Objectives The main objective of the present study was to determine the prevalence of aminoglycoside resistance among methicillin-resistant Staphylococcus aureus (MRSA) isolates in hospitalized patients in Sari and Tehran, Iran. Methods In this study, 174 MRSA strains isolated from different clinical samples, such as blood, sputum, tracheal exudates, bronchus, pleura, urine, wounds, and catheters, were collected from hospitalized patients in Tehran and Sari during 2014. Antibiotic susceptibility testing was performed against nine antibiotics with the Kirby-Bauer disk diffusion method according to CLSI guidelines. The MRSA strains were examined with oxacillin and cefoxitin disks. MRSA was then validated by detection of the mecA gene. PCR was used to evaluate the prevalence of the aminoglycoside-resistance genes aac (6’)-Ie/aph (2”), aph (3’)-IIIa, and ant (4’) among the MRSA isolates. Results The results of drug susceptibility testing showed that the highest rate of resistance was against erythromycin in Tehran (84.4%) and gentamicin (71.7%) in Sari. All isolates were sensitive to vancomycin, and all strains harbored the mecA gene. The aac (6’)-Ie/aph (2”), aph (3’)-IIIa, and ant (4’)-Ia genes were detected among 134 (77%), 119 (68.4%), and 122 (70.1%) of the isolates, respectively. Conclusions The present study showed a high prevalence of aminoglycoside-resistance genes among MRSA isolates in two cities in Iran.

  12. A bioinspired peptide scaffold with high antibiotic activity and low in vivo toxicity.

    Science.gov (United States)

    Rabanal, Francesc; Grau-Campistany, Ariadna; Vila-Farrés, Xavier; Gonzalez-Linares, Javier; Borràs, Miquel; Vila, Jordi; Manresa, Angeles; Cajal, Yolanda

    2015-05-29

    Bacterial resistance to almost all available antibiotics is an important public health issue. A major goal in antimicrobial drug discovery is the generation of new chemicals capable of killing pathogens with high selectivity, particularly multi-drug-resistant ones. Here we report the design, preparation and activity of new compounds based on a tunable, chemically accessible and upscalable lipopeptide scaffold amenable to suitable hit-to-lead development. Such compounds could become therapeutic candidates and future antibiotics available on the market. The compounds are cyclic, contain two D-amino acids for in vivo stability and their structures are reminiscent of other cyclic disulfide-containing peptides available on the market. The optimized compounds prove to be highly active against clinically relevant Gram-negative and Gram-positive bacteria. In vitro and in vivo tests show the low toxicity of the compounds. Their antimicrobial activity against resistant and multidrug-resistant bacteria is at the membrane level, although other targets may also be involved depending on the bacterial strain.

  13. Production of polypeptide antibiotic from Streptomyces parvulus and its antibacterial activity

    Directory of Open Access Journals (Sweden)

    Prakasham Reddy Shetty

    2014-01-01

    Full Text Available A highly potent secondary metabolite producing actinomycetes strain is isolated from marine soil sediments of Visakhapatnam sea coast, Bay of Bengal. Over all ten strains are isolated from the collected soil sediments. Among the ten actinomycetes strains the broad spectrum strain RSPSN2 was selected for molecular characterization, antibiotic production and its purification. The nucleotide sequence of the 1 rRNA gene (1261 base pairs of the most potent strain evidenced a 96% similarity with Streptomyces parvulus 1044 strain, Streptomyces parvulus NBRC 13193 and Streptomyces parvulus BY-F. From the taxonomic features, the actinomycetes isolate RSPSN2 matches with Streptomyces parvulus in the morphological, physiological and biochemical characters. Thus, it was given the suggested name Streptomyces parvulus RSPSN2. The active metabolite was extracted using ethyl acetate (1:3, v/v at pH 7.0. The separation of active ingredient and its purification was performed by using both thin layer chromatography (TLC and column chromatography (CC techniques. Spectrometric studies such as UV-visible, FTIR, and NMR and mass were performed. The antibacterial activity of pure compound was performed by cup plate method against some pathogenic bacteria including of streptomycin resistant bacteria like (Pseudomonas mirabilis. Pseudomonas putida and Bacillus cereus. In conclusion, the collected data emphasized the fact that a polypeptide antibiotic (Actinomycin D was produced by Streptomyces parvulus RSPSN2.

  14. Antimicrobial activity of nisin against the swine pathogen Streptococcus suis and its synergistic interaction with antibiotics.

    Science.gov (United States)

    Lebel, Geneviève; Piché, Fanny; Frenette, Michel; Gottschalk, Marcelo; Grenier, Daniel

    2013-12-01

    Streptococcus suis serotype 2 is known to cause severe infections in pigs, including meningitis, endocarditis and pneumonia. Furthermore, this bacterium is considered an emerging zoonotic agent. Recently, increased antibiotic resistance in S. suis has been reported worldwide. The objective of this study was to evaluate the potential of nisin, a bacteriocin of the lantibiotic class, as an antibacterial agent against the pathogen S. suis serotype 2. In addition, the synergistic activity of nisin in combination with conventional antibiotics was assessed. Using a plate assay, the nisin-producing strain Lactococcus lactis ATCC 11454 proved to be capable of inhibiting the growth of S. suis (n=18) belonging to either sequence type (ST)1, ST25, or ST28. In a microdilution broth assay, the minimum inhibitory concentration (MIC) of purified nisin ranged between 1.25 and 5 μg/mL while the minimum bactericidal concentration (MBC) was between 5 and 10 μg/mL toward S. suis. The use of a capsule-deficient mutant of S. suis indicated that the presence of this polysaccharidic structure has no marked impact on susceptibility to nisin. Following treatment of S. suis with nisin, transmission electron microscopy observations revealed lysis of bacteria resulting from breakdown of the cell membrane. A time-killing curve showed a rapid bactericidal activity of nisin. Lastly, synergistic effects of nisin were observed in combination with several antibiotics, including penicillin, amoxicillin, tetracycline, streptomycin and ceftiofur. This study brought clear evidence supporting the potential of nisin for the prevention and treatment of S. suis infections in pigs.

  15. Azurocidin, a natural antibiotic from human neutrophils: expression, antimicrobial activity, and secretion.

    Science.gov (United States)

    Almeida, R P; Vanet, A; Witko-Sarsat, V; Melchior, M; McCabe, D; Gabay, J E

    1996-06-01

    The azurophil granules of human PMN contain four antibiotic proteins, the serprocidins, which have extensive homology to one another and to serine proteases. Azurocidin, a member of this family, is a 29-kDa glycoprotein with broad spectrum antimicrobial activity and chemotactic activity toward monocytes. Insect cells transfected with a baculovirus vector carrying azurocidin cDNA produced a recombinant azurocidin protein. We purified the recombinant azurocidin protein from the culture medium of the infected cells and showed that it retained the antimicrobial activity of the native neutrophil-derived molecule. In addition, we present evidence that a 49-amino-acid region of the recombinant azurocidin protein is required for its secretion from insect cells. PMID:8776752

  16. Antibiotic Resistance

    Science.gov (United States)

    ... lives. But there is a growing problem of antibiotic resistance. It happens when bacteria change and become able ... resistant to several common antibiotics. To help prevent antibiotic resistance Don't use antibiotics for viruses like colds ...

  17. C-Geranylated flavonoids from Paulownia tomentosa fruits with antimicrobial potential and synergistic activity with antibiotics.

    Science.gov (United States)

    Navrátilová, Alice; Nešuta, Ondřej; Vančatová, Irena; Čížek, Alois; Varela-M, Ruben E; López-Abán, Julio; Villa-Pulgarin, Janny A; Mollinedo, Faustino; Muro, Antonio; Žemličková, Helena; Kadlecová, Daniela; Šmejkal, Karel

    2016-08-01

    Context C-6-Geranylated flavonoids possess promising biological activities. These substances could be a source of lead compounds for the development of therapeutics. Objective The study was designed to evaluate their antibacterial and antileishmanial activity. Materials and methods C-6-Geranylated flavanones were tested in micromolar concentrations against promastigote forms of Leishmania brazilensis, L. donovani, L. infantum, and L. panamensis against methicillin-resistant Staphylococcus aureus (MRSA); and synergistic potential with antibiotics was analyzed. IC50 values (after 72 h) were calculated and compared with that of miltefosine. Flow cytometry and DNA fragmentation analysis were used the mechanism of the effect. Geranylated flavanones or epigallocatechin gallate were combined with oxacillin, tetracycline, and ciprofloxacin, and the effects of these two-component combinations were evaluated. Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were established (after 24 h), the synergy was measured by the checkerboard titration technique, and the sums of the fractional inhibitory concentrations (∑FICs) were computed. Results 3'-O-Methyl-5'-O-methyldiplacone and 3'-O-methyldiplacone showed good antileishmanial activities (IC50 8-42 μM). 3'-O-Methyl-5'-hydroxydiplacone activates the apoptotic death at leishmanias, the effect of 3'-O-methyl-5'-O-methyldiplacone has another mechanism. The test of the antibacterial activity showed good effects of 3'-O-methyldiplacol and mimulone against MRSA (MIC 2-16 μg/mL), and in six cases, the results showed synergistic effects when combined with oxacillin. Synergistic effects were also found for the combination of epigallocatechin gallate with tetracycline or oxacillin. Conclusion This work demonstrates anti-MRSA and antileishmanial potential of geranylated flavanones and uncovers their promising synergistic activities with antibiotics. In addition, the mechanism of

  18. Evaluation of antibacterial activity and synergistic effect between antibiotic and the essential oils of some medicinal plants

    Institute of Scientific and Technical Information of China (English)

    Fadila Moussaoui; Tajelmolk Alaoui

    2016-01-01

    Objective: To demonstrate the in vitro antibacterial properties of five essential oils against ten bacterial strains and study the synergistic effect of the combination of essential oils with standard antibiotics. Methods: Origanum compactum, Chrysanthemum coronarium, Thymus willdenowii Boiss, Melissa officinalis and Origanum majorana L. were used alone and combined used with standard antibiotics to evaluate their antimicrobial activities. The disk diffusion method was employed. Results: The results showed that the combined application of the essential oils of the plants with antibiotics led to a synergistic effect in some cases, but antagonistic effect was also observed in some bacteria. Conclusions: This study shows that the combination of essential oils of the five plants with antibiotics may be useful in the fight against emerging microbial drug resistance.

  19. Study on in vitro antimicrobial activity of Colistin and other antibiotics against Acinetobacter baumannii%粘菌素等抗菌药物对临床分离鲍曼不动杆菌的抗菌活性

    Institute of Scientific and Technical Information of China (English)

    李然; 史录文; 王睿; 梁蓓蓓; 宋秀杰; 蔡芸

    2009-01-01

    AIM: To investigate the antimicrobial activity of Colistin and other antibiotics against Acine-tobacter baumannii. METHODS: The agar dilution method was used to determine the minimum inhibitory concentrations (MICs) of Colistin and other antibiotics against 70 Acinetobacter baumannii collected from PLA General Hospital, Peking Hospital and Beijing Union Hospital. The sensitive rate was judged by CLSI stan- dard. RESULTS: The resistant rates of 70 Acineto-bacter baumannii to penicillins and cephalosporins, carbopenems ( meropenem and imipenem/eilastatin ), aminoglycosides(netilmicin and amikacin) , fluoroquin-olones(ciprofloxacin and levofloxacin) were 71.4% -82.9%, 75.7% - 77.1%, 71.4% - 75.7%, 32.8% - 82.9% . Fifty-five multidrug-resistant Acin-etobacter baumannii were isolated. All Acinetobacter baumannii in the study were sensitive to Colistin, the MIC_(50) and MIG_(90) were both 1 μg/mL. CONCLU- SION : Acinetobacter baumannii in the study were resistant to many antibiotics including penicillins and cephalosporins, carbopenems, aminoglycosides. Colistin has good antimicrobial activity against Aeinetobacter baumannii.%目的:评价粘菌素对临床分离多药耐药鲍曼不动杆菌的抗菌活性.方法:收集解放军总医院、北京医院、北京协和医院3家医院分离的非重复分离鲍曼不动杆菌70株,采用琼脂稀释法测定粘菌素与其他12种抗菌药物的最低抑菌浓度(MIC),以CLSI标准判断其敏感率.结果:70株鲍曼不动杆菌,对青霉素类和头孢菌素类的耐药率为71.4%~82.9%,对碳青霉烯类(美罗培南、亚胺培南/西司他丁)的耐药率为75.7%~77.1%,对氨基糖苷类(奈替米星、阿米卡星)的耐药率为71.4%~75.7%,对氟喹酮类的耐药率(环丙沙星、左氧氟沙星)为32.9%~82.9%.共筛选出多药耐药鲍曼不动杆菌55株,对粘菌素全部敏感,MIC_(50)和MIC_(90)均为1/μg/mL.结论:鲍曼不动杆菌对本研究的大多数抗菌药物耐药率较高,粘菌素

  20. In vitro Antibacterial Activity of Combretum edwardsii, Combretum krausii, and Maytenus nemorosa and Their Synergistic Effects in Combination with Antibiotics.

    Science.gov (United States)

    Chukwujekwu, Jude C; van Staden, Johannes

    2016-01-01

    The study investigated the antibacterial activity of crude extracts of C. edwardsii, Combretum krausii, and Maytenus nemorosa as well as their interactions with selected antibiotics against drug resistant bacterial strains. Using the rapid p-iodonitrotetrazolium chloride colorimetric assay, minimum inhibitory concentration values of plant extracts and antibiotics were determined. The interactions of plant extracts and antibiotics were studied using a checkerboard method. The MICs of the plant extracts and antibiotics were in the range of 0.037-6.25 and 0.001-2.5 mg/ml, respectively. The plant fractions tested in the present study displayed varying levels of antibacterial activity depending on the bacterial strains. Generally, Staphylococcus aureus was the most susceptible of the three strains of bacteria while the other two beta-lactamase producing Gram-negative bacteria were the most resistant. The hexane leaf extract of M. nemorosa was the most active (MIC = 37 μg/ml) against S. aureus. Ethyl acetate leaf extract of C. krausii was the most active against Klebsiella pneumoniae and ethyl acetate leaf extract of C. edwardsii was the most active against Escherichia coli. Synergistic interactions were detected in 13% of the combinations against E. coli, 27% of the combinations against K. pneumoniae and 80% of the combinations against S. aureus. The few synergistic interactions observed in the present study suggest that the crude extracts of the leaves of M. nemorosa, C. edwardsii, and C. krausii could be potential sources of broad spectrum antibiotic resistance modifying compounds. PMID:27471466

  1. Surveillance and Control of Antibiotic Resistance in the Mediterranean Region.

    Science.gov (United States)

    Ricciardi, Walter; Giubbini, Gabriele; Laurenti, Patrizia

    2016-01-01

    Antibiotic resistance is one of the most relevant problems in the healthcare: the growth of resistant microorganisms in healthcare settings is a worrisome threat, raising length to stay (LOS), morbidity and mortality in those patients. The importance of the antibiotic resistance and its spread around the world, gave rise to the activation of several surveillance systems, based especially on the collection of laboratory data to local or national level. The objective of this work is to carry out a review of the scientific literature existing on the topic and scientific activities related to surveillance of antibiotic resistance in the countries bordering the Mediterranean Sea. Recent Data from European Centre for Disease Prevention and Control (November 2015) show, for different combinations bacterium-drug, an increase of resistance from North to South and from West to East of Europe. It is of particular concern the phenomenon of resistance carried out by some gram-negative, specifically Klebsiella pneumoniae and Escherichia coli to third-generation cephalosporin, often combined in opposition to fluoroquinolones and aminoglycosides. Is particularly high the incidence of resistance to carbapenems by strains of Enterobacteriaceae (Klebsiella included). The resistance exerted by MRSA (Methicillin-resistant Staphylococcus aureus) continues to be relevant, albeit showing some decline in recent years. The incidence of resistance carried on by Streptococcus pneumoniae is stable and is mainly relevant to macrolides. Finally, a significant increase in recording relatively exercised by Enterococcus faecium to Vancomycin. Detecting, preventing, and controlling antibiotic resistance requires strategic, coordinated, and sustained efforts. It also depends on the engagement of governments, academia, industry, healthcare providers, the general public, and the agricultural community, as well as international partners. Committing to combating antibiotic-resistant microbes does support

  2. Enhancement of antibiotic activity by efflux inhibitors against multidrug resistant Mycobacterium tuberculosis clinical isolates from Brazil

    Directory of Open Access Journals (Sweden)

    Tatiane eCoelho

    2015-04-01

    Full Text Available Drug resistant tuberculosis continues to increase and new approaches for its treatment are necessary. The identification of M. tuberculosis clinical isolates presenting efflux as part of their resistant phenotype has a major impact in tuberculosis treatment. In this work, we used a checkerboard procedure combined with the tetrazolium microplate-based assay (TEMA to study single combinations between antituberculosis drugs and efflux inhibitors (EIs against multidrug resistant M. tuberculosis clinical isolates using the fully susceptible strain H37Rv as reference. Efflux activity was studied on a real-time basis by a fluorometric method that uses ethidium bromide as efflux substrate. Quantification of efflux pump genes mRNA transcriptional levels were performed by RT-qPCR. The fractional inhibitory concentrations (FIC indicated synergistic activity for the interactions between isoniazid, rifampicin, amikacin, ofloxacin, and ethidium bromide plus the EIs verapamil, thioridazine and chlorpromazine. The FICs ranged from 0.25, indicating a four-fold reduction on the MICs, to 0.015, 64-fold reduction. The detection of active efflux by real-time fluorometry showed that all strains presented intrinsic efflux activity that contributes to the overall resistance which can be inhibited in the presence of the EIs. The quantification of the mRNA levels of the most important efflux pump genes on these strains shows that they are intrinsically predisposed to expel toxic compounds as the exposure to subinhibitory concentrations of antibiotics were not necessary to increase the pump mRNA levels when compared with the non-exposed counterpart. The results obtained in this study confirm that the intrinsic efflux activity contributes to the overall resistance in multidrug resistant clinical isolates of M. tuberculosis and that the inhibition of efflux pumps by the EIs can enhance the clinical effect of antibiotics that are their substrates.

  3. Microplate phosphocellulose binding assay for aminoglycoside-modifying enzymes.

    OpenAIRE

    Cooksey, R C; Metchock, B G; Thornsberry, C

    1986-01-01

    We modified the phosphocellulose binding assay for aminoglycoside-modifying enzymes (AMEs) by use of microdilution plates and a multichannel micropipette. Batteries of aminoglycoside substrates for screening organisms for the presence of AMEs as well as for subclassifying enzymes were prepared and stored in microdilution plates. When tested in parallel with the conventional tube reaction assay, the microplate assay yielded comparable radioactive counts and therefore equally correct identifica...

  4. In vitro antibiotic susceptibilities of Burkholderia mallei (causative agent of glanders) determined by broth microdilution and E-test.

    Science.gov (United States)

    Heine, H S; England, M J; Waag, D M; Byrne, W R

    2001-07-01

    In vitro susceptibilities to 28 antibiotics were determined for 11 strains of Burkholderia mallei by the broth microdilution method. The B. mallei strains demonstrated susceptibility to aminoglycosides, macrolides, quinolones, doxycycline, piperacillin, ceftazidime, and imipenem. For comparison and evaluation, 17 antibiotic susceptibilities were also determined by the E-test. E-test values were always lower than the broth dilution values. Establishing and comparing antibiotic susceptibilities of specific B. mallei strains will provide reference information for assessing new antibiotic agents.

  5. Antibiotics in otorhinolaryngology practice

    Directory of Open Access Journals (Sweden)

    Stefan-Mikić Sandra

    2002-01-01

    Full Text Available Introduction This study investigated utilization of antibacterial agents at the Ear, Nose and Throat Department of the Outpatient Service of the Health Center Novi Sad - Liman and at the Ear, Nose and Throat Clinic of the Clinical Center Novi Sad, in the period February - March 2001. Material and methods All antibacterial agents were classified as group J, regarding Anatomic-Therapeutic-Chemical Classification. Data on drug utilization were presented in Defined Daily Doses (DDD. Patients who were under observation were all treated with antibiotics. Results In regard to prescribed treatment in the Ear, Nose and Throat Department of the Outpatient Service of the Health Center Novi Sad - Liman, most outpatients were treated with macrolide antibiotics - in 26.21%; combination of penicillin and beta-lactamase inhibitors in 20.83% and pyranosides in 16.12%. At the Ear, Nose and Throat Clinic of the Clinical Center Novi Sad, macrolides and lincosamines were most frequently used - in 20.46%; cephalosporins in 19.87% and penicillins susceptible to beta-lactamase in 18.85%. It is extremely positive and in agreement with current pharmacotherapeutic principles that in both institutions peroral ampicillins have not been prescribed. Aminoglycosides have been prescribed in less than 1% of patients of the Ear, Nose and Throat Department of the Outpatient Service of the Health Center Novi Sad - Liman, whereas they were much more frequently prescribed at the Ear, Nose and Throat Clinic of the Clinical Center Novi Sad - in 11.25%. Although there is a positive postantibiotic effect in regard to these antibiotics and it is recommended to use them once a day, in both examined institutions aminoglycosides were given twice a day. In regard to bacterial identification it was done in 80.76% of patients of the Ear, Nose and Throat Department of the Outpatient Service of the Health Center Novi Sad - Liman, while in the Ear, Nose and Throat Clinic of the Clinical Center

  6. Antibiotic usage in 2013 on a dairy CAFO in NY State, USA

    OpenAIRE

    Sarenbo, Sirkku; Doane, Marie

    2014-01-01

    Antimicrobial resistance is threatening humans and animals worldwide. Biosecurity and 1-year usage of antibiotics on a dairy concentrated animal feeding operation (CAFO) in NY State, USA, were mapped: how much antibiotics were used, for what purpose, and whether any decrease could be warranted. Approximately 493 kg antibiotics was used, of which 376 kg was ionophores (monensin and lasalocides), 79 kg penicillin, 16.5 kg lincosamides, 8.0 kg aminoglycosides, 7.7 kg sulfamides, 3.4 kg cephalosp...

  7. Penicillin-bound polyacrylate nanoparticles: restoring the activity of beta-lactam antibiotics against MRSA.

    Science.gov (United States)

    Turos, Edward; Reddy, G Suresh Kumar; Greenhalgh, Kerriann; Ramaraju, Praveen; Abeylath, Sampath C; Jang, Seyoung; Dickey, Sonja; Lim, Daniel V

    2007-06-15

    This report describes the preparation of antibacterially active emulsified polyacrylate nanoparticles in which a penicillin antibiotic is covalently conjugated onto the polymeric framework. These nanoparticles were prepared in water by emulsion polymerization of an acrylated penicillin analogue pre-dissolved in a 7:3 (w:w) mixture of butyl acrylate and styrene in the presence of sodium dodecyl sulfate (surfactant) and potassium persulfate (radical initiator). Dynamic light scattering analysis and atomic force microscopy images show that the emulsions contain nanoparticles of approximately 40 nm in diameter. The nanoparticles have equipotent in vitro antibacterial properties against methicillin-susceptible and methicillin-resistant forms of Staphylococcus aureus and indefinite stability toward beta-lactamase. PMID:17420125

  8. [Susceptibility to antibiotics and biochemical activity of strains of Acinetobacter sp. isolated from various sources].

    Science.gov (United States)

    Gospodarek, E

    1993-01-01

    The study was performed on 576 Acinetobacter strains isolated from clinical material, objects from hospital, environment, soil, water and from animals. Applying API 20NE system identification was following: A. baumanii (61.1%), A. junii (19.4%), A. haemolyticus (4.3%), A. lwoffii (3.3%), A. johnsonii (0.52%) and not belonging to above genus strains (11.3%). Over 47% strains of Acinetobacter were isolated from clinical material as the only bacteria (mainly from samples received from intensive care units and surgical and urological wards). Out of 23 antibiotics and antimicrobials used for investigation of 535 strains of Acinetobacter, most active were imipenem (99%) of susceptible strains, ofloxacin and ciprofloxacin (95%) and netilmicin (88%). Multiple resistant strains were isolated more frequently from hospital environment than from other sources--these were mostly A. baumanii and A. junii. PMID:8189806

  9. Differential trypanocidal activity of novel macrolide antibiotics; correlation to genetic lineage.

    Directory of Open Access Journals (Sweden)

    Carolina Aquilino

    Full Text Available Here we report the systematic study of the anti-trypanocidal activity of some new products derived from S. diastatus on 14 different T. cruzi strains spanning the six genetic lineages of T. cruzi. As the traditional growth inhibition curves giving similar IC(50 showed great differences on antibiotic and lineage tested, we decided to preserve the wealth of information derived from each inhibition curve and used an algorithm related to potency of the drugs, combined in a matrix data set used to generate a cluster tree. The cluster thus generated based just on drug susceptibility data closely resembles the phylogenies of the lineages derived from genetic data and provides a novel approach to correlate genetic data with phenotypes related to pathogenesis of Chagas disease. Furthermore we provide clues on the drugs mechanism of action.

  10. Study of Klebsiella pneumoniae producing extended-spectrum β-lactamases against aminoglycosides

    Institute of Scientific and Technical Information of China (English)

    WEI FENG SHI; SU JIAN WANG; JIAN PING QIN

    2007-01-01

    Klebsiella pneumoniae ( K. pneumoniae) is one of the main gram-negative bacilli in clinical practice. Nosocomial infections caused by K. pneumoniae producing extended-spectrum β-lactamases (ESBLs) are very difficult to treat. This paper investigated the resistant characteristics of K. pneumoniae producing ESBLs and their aminoglycoside-modifying enzyme gene expressions including Nacetyltransferases and O-adenyhransferases. Bacteria identification and ESBLs confirmatory tests were performed by Phoenix TM-100 system. And minimum inhibitory concentrations (MICs) of gentamicin,amikacin, kanamycin, tobramycin, netilmicin and neomycin in 53 K. pneumoniae isolates were detected by agar dilution. In addition, six aminoglycoside-modifying enzyme genes were amplified by polymerase chain reaction (PCR) and verified by DNA sequencer. It was found that imipenem and meropenem against 120 K. pneumoniae isolates produced powerful antimicrobial activities. The resistant rates of gentamicin and amikacin were 55.0% and 46.7%, respectively. Except neomycin,MIC50 and MIC90 of gentamicin, amikacin, kanamycin, tobramycin and netilmicin in 53 K. pneumoniae were all > 128 μg/ml, and the resistant rates were 83.0%, 52.3%, 75.5%, 81. 1% and 69.8%, respectively. However, neomycin was only 39.6%. In addition, five modifying enzyme genes, including aac(3)- Ⅰ , aac(3)-Ⅱ, aac(6′) - Ⅰ b, ant(3″) - Ⅰ, ant(2″) - Ⅰ genes, were found in 53 isoahes except aac (6′)-Ⅱ, and their positive rates were 11.3%, 67.9%, 47.2%,1.9 % and 39.6 %, respectively. It was also confirmed by nucleotide sequence analysis that the above resistant genes shared nearly 100% identities with GenBank published genes. The results obtained in the present study indicated that K. pneumoniae producing ESBLs strains are rapidly spreading in our hospital, and their resistance to aminoglycosides may be associated with aminoglycoside-modifying enzyme gene expressions.

  11. Plasmid-Mediated High-Level Resistance to Aminoglycosides in Enterobacteriaceae Due to 16S rRNA Methylation

    OpenAIRE

    Galimand, Marc; Courvalin, Patrice; Lambert, Thierry

    2003-01-01

    A self-transferable plasmid of ca. 80 kb, pIP1204, conferred multiple-antibiotic resistance to Klebsiella pneumoniae BM4536, which was isolated from a urinary tract infection. Resistance to β-lactams was due to the blaTEM1 and blaCTX-M genes, resistance to trimethroprim was due to the dhfrXII gene, resistance to sulfonamides was due to the sul1 gene, resistance to streptomycin-spectinomycin was due to the ant3"9 gene, and resistance to nearly all remaining aminoglycosides was due to the aac3-...

  12. Antibiotic and disinfectant susceptibility profiles of vancomycin-resistant Enterococcus faecium (VRE) isolated from community wastewater in Texas.

    Science.gov (United States)

    Beier, Ross C; Duke, Sara E; Ziprin, Richard L; Harvey, Roger B; Hume, Michael E; Poole, Toni L; Scott, H Morgan; Highfield, Linda D; Alali, Walid Q; Andrews, Kathleen; Anderson, Robin C; Nisbet, David J

    2008-03-01

    Vancomycin-resistant Enterococcus faecium (VRE) from human wastewater effluents in a nonclinical semiclosed agri-food system in Texas were characterized for susceptibility to antibiotics and disinfectants. The 50 VRE were resistant to eight fluoroquinolones and 10 of 17 antimicrobials typically active against Gram-positive organisms. The VRE were susceptible to quinupristin/dalfopristin and linezolid. Lack of the insertion element IS1251 correlated with VRE susceptibility to streptomycin and gentamicin at p or =2 ppm. Triclosan MICs for many of the VRE were well over expected product application levels. No association was observed between antibiotic resistance and disinfectant susceptibility in these VRE. Enterococci multiply-resistant to vancomycin and aminoglycosides were found in a non-hospital environment where one would not expect to find them. PMID:18193143

  13. ASSESSMENT OF ANTIMICROBIAL ACTIVITY OF PUNICA GRANATUM AGAINST ANTIBIOTIC-RESISTANT CLOSTRIDIUM PERFRINGENS TYPE (D)

    OpenAIRE

    FRDOOS AL FADEL , SHAZA AL LAHAM, HASSANA CHOUR

    2015-01-01

    The search for new antibiotics and alternative products to solve the increasing number of bacterial resistance to customary antibiotics has become an urgent need. To investigate the effectiveness of the extracts prepared from different parts of Syrian Punica granatum Linn (family Punicaceae), against Clostridium perfringens type (D), which is resistant against many antibiotics, 684 samples were isolated from intestines and livers of death goats by using blood agar, and a selective agar for gr...

  14. Mannitol enhances antibiotic sensitivity of persister bacteria in Pseudomonas aeruginosa biofilms.

    Directory of Open Access Journals (Sweden)

    Nicolas Barraud

    Full Text Available The failure of antibiotic therapies to clear Pseudomonas aeruginosa lung infection, the key mortality factor for cystic fibrosis (CF patients, is partly attributed to the high tolerance of P. aeruginosa biofilms. Mannitol has previously been found to restore aminoglycoside sensitivity in Escherichia coli by generating a proton-motive force (PMF, suggesting a potential new strategy to improve antibiotic therapy and reduce disease progression in CF. Here, we used the commonly prescribed aminoglycoside tobramycin to select for P. aeruginosa persister cells during biofilm growth. Incubation with mannitol (10-40 mM increased tobramycin sensitivity of persister cells up to 1,000-fold. Addition of mannitol to pre-grown biofilms was able to revert the persister phenotype and improve the efficacy of tobramycin. This effect was blocked by the addition of a PMF inhibitor or in a P. aeruginosa mutant strain unable to metabolise mannitol. Addition of glucose and NaCl at high osmolarity also improved the efficacy of tobramycin although to a lesser extent compared to mannitol. Therefore, the primary effect of mannitol in reverting biofilm associated persister cells appears to be an active, physiological response, associated with a minor contribution of osmotic stress. Mannitol was tested against clinically relevant strains, showing that biofilms containing a subpopulation of persister cells are better killed in the presence of mannitol, but a clinical strain with a high resistance to tobramycin was not affected by mannitol. Overall, these results suggest that in addition to improvements in lung function by facilitating mucus clearance in CF, mannitol also affects antibiotic sensitivity in biofilms and does so through an active, physiological response.

  15. Alkaloids: an overview of their antibacterial, antibiotic-enhancing and antivirulence activities.

    Science.gov (United States)

    Cushnie, T P Tim; Cushnie, Benjamart; Lamb, Andrew J

    2014-11-01

    With reports of pandrug-resistant bacteria causing untreatable infections, the need for new antibacterial therapies is more pressing than ever. Alkaloids are a large and structurally diverse group of compounds that have served as scaffolds for important antibacterial drugs such as metronidazole and the quinolones. In this review, we highlight other alkaloids with development potential. Natural, semisynthetic and synthetic alkaloids of all classes are considered, looking first at those with direct antibacterial activity and those with antibiotic-enhancing activity. Potent examples include CJ-13,136, a novel actinomycete-derived quinolone alkaloid with a minimum inhibitory concentration of 0.1 ng/mL against Helicobacter pylori, and squalamine, a polyamine alkaloid from the dogfish shark that renders Gram-negative pathogens 16- to >32-fold more susceptible to ciprofloxacin. Where available, information on toxicity, structure-activity relationships, mechanisms of action and in vivo activity is presented. The effects of alkaloids on virulence gene regulatory systems such as quorum sensing and virulence factors such as sortases, adhesins and secretion systems are also described. The synthetic isoquinoline alkaloid virstatin, for example, inhibits the transcriptional regulator ToxT in Vibrio cholerae, preventing expression of cholera toxin and fimbriae and conferring in vivo protection against intestinal colonisation. The review concludes with implications and limitations of the described research and directions for future research. PMID:25130096

  16. Antibacterial Activities of Selected Cameroonian Plants and Their Synergistic Effects with Antibiotics against Bacteria Expressing MDR Phenotypes

    Directory of Open Access Journals (Sweden)

    Stephen T. Lacmata

    2012-01-01

    Full Text Available The present work was designed to assess the antibacterial properties of the methanol extracts of some Cameroonian medicinal plants and the effect of their associations with currently used antibiotics on multidrug resistant (MDR Gram-negative bacteria overexpressing active efflux pumps. The antibacterial activities of twelve methanol extracts of medicinal plants were evaluated using broth microdilution. The results of this test showed that three extracts Garcinia lucida with the minimal inhibitory concentrations (MIC varying from 128 to 512 μg/mL, Garcinia kola (MIC of 256 to 1024 μg/mL, and Picralima nitida (MIC of 128 to 1024 μg/mL were active on all the twenty-nine studied bacteria including MDR phenotypes. The association of phenylalanine arginine β-naphthylamide (PAβN or efflux pumps inhibitor to different extracts did not modify their activities. At the concentration of MIC/2 and MIC/5, the extracts of P. nitida and G. kola improved the antibacterial activities of some commonly used antibiotics suggesting their synergistic effects with the tested antibiotics. The results of this study suggest that the tested plant extracts and mostly those from P. nitida, G. lucida and G. kola could be used alone or in association with common antibiotics in the fight of bacterial infections involving MDR strains.

  17. Antibacterial activity of some medicinal mangroves against antibiotic resistant pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Abeysinghe P

    2010-01-01

    Full Text Available The antibacterial activity of the leaves and bark of mangrove plants, Avicennia marina, A. officinalis, Bruguiera sexangula, Exoecaria agallocha, Lumnitzera racemosa, and Rhizophora apiculata was evaluated against antibiotic resistant pathogenic bacteria, Staphylococcus aureus and Proteus sp. Soxhlet extracts of petroleum ether, ethyl acetate, ethanol and water were prepared and evaluated the antibacterial activity using agar diffusion method. Most of the plant extracts showed promising antibacterial activity against both bacterial species. However, higher antibacterial activity was observed for Staphylococcus aureus than Proteus sp. The highest antibacterial activity was shown by ethyl acetate of mature leaf extracts of E. agallocha for Staphylococcus aureus. All ethyl acetate extracts showed higher inhibition against S. aureus while some extracts of chloroform, ethyl acetate and ethanol gave inhibition against Proteus sp. None of the petroleum ether and aqueous extracts showed inhibition against Proteus sp. All fresh plant materials did also show more antibacterial activity against both bacterial strains than did dried plant extracts. Antibacterial activity of fresh and dried plant materials reduced for both bacterial strains with time after extraction. Since L. racemosa and A. marina gave the best inhibition for bacterial species, they were used for further investigations. Charcoal treated plant extracts of L. racemosa and A. marina were able to inhibit both bacterial strains more than those of untreated plant extracts. Phytochemical screening of mature leaf, bark of L. racemosa and leaf extracts of A. marina has been carried out and revealed that leaf and bark contained alkaloids, steroids, triterpenoids and flavonoids. None of the above extracts indicate the presence of saponins and cardiac glycosides. Separated bands of extracts by TLC analysis showed antibacterial activity against S. aureus.

  18. Factors impacting the aminoglycoside-induced UGA stop codon readthrough in selenoprotein translation.

    Science.gov (United States)

    Martitz, Janine; Hofmann, Peter Josef; Johannes, Jörg; Köhrle, Josef; Schomburg, Lutz; Renko, Kostja

    2016-09-01

    Aminoglycosides (AG) are oligosaccharide antibiotics that interfere with the small ribosomal subunit in aerobic, Gram-negative bacteria, causing pathogen-destructing error rates in their protein biosynthesis. Aminoglycosides also induce mRNA misinterpretation in eukaryotic cells, especially of the UGA (Opal)-stop codon, albeit to a lower extent. UGA recoding is essentially required for the incorporation of selenocysteine (Sec) into growing selenoproteins during translation. Selenocysteine incorporation requires the presence of a selenoprotein-specific stem-loop structure within the 3'-untranslated region of the mRNA, the so-called Sec-insertion sequence (SECIS) element. Interestingly, selenoprotein genes differ in their SECIS-element sequence and in their UGA base context. We hypothesized that the SECIS-element and the specific codon context synergize in controlling the effects of AG on stop codon readthrough. To this end, the SECIS-elements of glutathione peroxidase 1, glutathione peroxidase 4 and selenoprotein P transcripts were cloned into a reporter system and analyzed in combination with different UGA codon contexts. Our results indicate that a cytosine in position 4 (directly downstream of UGA) confers strongest effects on both the Se- and AG-dependent readthrough. Overall selenoprotein biosynthesis rate depends on the Se-status, AG concentration and the specific SECIS-element present in the transcript. These findings help to get a better understanding for the susceptibility of different transcripts towards AG-mediated interference with the biosynthesis of functional Se-containing selenoproteins, and highlight the importance of the Se-status for successful selenoprotein biosynthesis under antibiotic therapy. PMID:27157664

  19. Influence of a macrolide antibiotic, roxithromycin, on mast cell growth and activation in vitro

    Directory of Open Access Journals (Sweden)

    Toshikazu Shimane

    2001-01-01

    Full Text Available Background: Long-term administration of macrolide antibiotics is recognized to be able to favorably modify the clinical condition of inflammatory diseases, such as diffuse panbronchiolitis and cystic fibrosis. However, the precise mechanisms by which macrolide antibiotics could improve clinical conditions of the patients are not well understood.

  20. On the Enhanced Antibacterial Activity of Antibiotics Mixed with Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Shantrokha AN

    2009-01-01

    Full Text Available Abstract The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles onEscherichia coliK12 was examined by the agar-well-diffusion method, enumeration of colony-forming units, and turbidimetry. Addition of gentamicin to colloidal gold changed the gold color and extinction spectrum. Within the experimental errors, there were no significant differences in antibacterial activity between pure gentamicin and its mixture with gold nanoparticles (NPs. Atomic absorption spectroscopy showed that upon application of the gentamicin-particle mixture, there were no gold NPs in the zone of bacterial-growth suppression in agar. Yet, free NPs diffused into the agar. These facts are in conflict with the earlier findings indicating an enhancement of the bacterial activity of similar gentamicin–gold nanoparticle mixtures. The possible causes for these discrepancies are discussed, and the suggestion is made that a necessary condition for enhancement of antibacterial activity is the preparation of stable conjugates of NPs coated with the antibiotic molecules.

  1. Antibiotic pigment from desert soil actinomycetes; biological activity, purification and chemical screening

    Directory of Open Access Journals (Sweden)

    Selvameenal L

    2009-01-01

    Full Text Available An actinomycete strain, Streptomyces hygroscopicus subsp. ossamyceticus (strain D10 was isolated from Thar Desert soil, Rajasthan during the year 2006 and found to produce a yellow color pigment with antibiotic activity. Crude pigment was produced from strain D10 by solid state fermentation using wheat bran medium followed by extraction with ethyl acetate. The antimicrobial activity of the crude pigment was evaluated against drug resistant pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Staphylococcus aureus, extended spectrum b-lactamase producing cultures of Escherichia coli, Pseudomonas aeruginosa and Klebsiella sp. About 420 mg of crude pigment was produced per 10 g of wheat bran medium. In the disc diffusion method the crude ethyl acetate extract showed a minimum of 10 mm inhibition against Klebsiella sp. and maximum of 19 mm of inhibition against Escherichia coli. The crude pigment was partially purified using thin layer chromatography with the solvent system chloroform:methanol (30:70 and the Rf value was calculated as 0.768. Antimicrobial activity of the partially purified compound from thin layer chromatography was determined using the bioautography method. The purified pigment showed minimum of 15 mm inhibition against Klebsiella sp. and a maximum of 23 mm of inhibition against vancomycin-resistant Staphylococcus aureus in the disc diffusion method. Based on the results of chemical screening, the pigment was tentatively identified as group of sugar containing molecules.

  2. Comparative Evaluation of the Modulation of Antibiotic-Activity against Strains of Escherichia coli and Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Henrique D. M. Coutinho

    2015-09-01

    Full Text Available Introduction: Combining multiple drugs is an strategy used to combat the dissemination of pathogenic and drug resistant bacteria. However, the misuse of these drugs against bacteria have caused the selection of more resistant specimens called multidrug-resistant bacteria. Objective: In this work we evaluated the antibiotic activity of claritromicin, gentamicin, ciprofloxacin and imipenen, alone or associating one by one, against strains of Escherichia coli and Staphylococcus aureus. Material and methods: The minimal inhibitory concentration (mic was performed us­ing the microdilution assay. Based in the mic values, the antibiotic effect of the drugs alone and in association were determined. Results: The association between the drugs demonstrated the synergism against the bacterial strains. Conclusion: The use of the combined antibiotic-therapy can be positively performed, but additional studies have to be conducted first for proving that its use is safe.

  3. Antibiotics Quiz

    Science.gov (United States)

    ... Recommendations Pediatric Treatment Recommendations Inpatient Healthcare Professionals Community Pharmacists Continuing Education & Curriculum Opportunities Weighing in on Antibiotic Resistance Improving Prescribing Outpatient Antibiotic Stewardship Interventions That Work Systematic Reviews ...

  4. Relationship between antimicrobial resistance and aminoglycoside-modifying enzyme gene expressions in Acinetobacter baumannii

    Institute of Scientific and Technical Information of China (English)

    SHI Wei-feng; JIANG Jian-ping; MI Zu-huang

    2005-01-01

    Background Acinetobacter baumannii is one of the main gram-negative bacilli in clinical practice. Nosocomial infections caused by multi-drug resistance Acinetobacter baumannii is very difficult to treat. This study was designed to investigate the antimicrobial resistance characteristics and four resistant gene expressions of aminoglycoside-modifying enzymes including N-acetyltransferases and O-phosphotransferases in Acinetobacter baumannii. Methods Bacterial identification and antimicrobial susceptibility test were performed by PhoenixTM system in 247 strains of Acinetobacter baumannii. Minimal inhibitory concentrations (MICs) of seven aminoglycosides including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin and streptomycin in 15 strains of multi-drug resistant Acinetobacter baumannii were detected by agar dilution. Four aminoglycoside-modifying enzyme genes were amplified by polymerase chain reaction (PCR) and verified by DNA sequencer.Results The resistance rates of 247 strains of Acinetobacter baumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracycline, ciprofloxacin and chloramphenicol were more than 50%. Imipenem and meropenem showed high antibacterial activities with resistance rates of 3.2% and 4.1%. MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanamycin in 15 strains of multi-drug resistant Acinetobacter baumanii were all more than 1024 mg/L, and the resistance rates were 100%, 100%, 100% and 93.3%, respectively. But their resistance rates to tobramycin, netilmicin and neomycin were 86.7%, 93.3% and 46.7%, respectively. Three modifying enzyme genes, including aacC1, aacC2 and aacA4 genes, were found in 15 strains, but aphA6 had not been detected. Their positive rates were 93.3%, 20.0% and 20.0%, respectively. These three genes existed simultaneously in No.19 strain. Nucleotide sequences of aacC1, aacC2 and aacA4 genes shared 100%, 97.9% and 99.7% identities with GenBank genes (AY307113, S68058 and AY

  5. The Antibiotic Resistance ‘Mobilome’: searching for the link between environment and clinic.

    Directory of Open Access Journals (Sweden)

    Julie ePerry

    2013-05-01

    Full Text Available Antibiotic resistance is an ancient problem, owing to the co-evolution of antibiotic-producing and target organisms in the soil and other environments over millennia. The environmental ‘resistome’ is the collection of all genes that directly or indirectly contribute to antibiotic resistance. Many of these resistance determinants originate in antibiotic-producing organisms (where they serve to mediate self-immunity, while others become resistance determinants only when mobilized and over-expressed in non-native hosts (like plasmid-based β-lactamases. The modern environmental resistome is under selective pressure from human activities such as agriculture, which may influence the composition of the local resistome and lead to gene transfer events. Beyond the environment, we are challenged in the clinic by the rise in both frequency and diversity of antibiotic resistant pathogens. We assume that clinical resistance originated in the environment, but few examples of direct gene exchange between the environmental resistome and the clinical resistome have been documented. Strong evidence exists to suggest that clinical aminoglycoside and vancomycin resistance enzymes, the extended-spectrum β-lactamase CTX-M and the quinolone resistance gene Qnr have direct links to the environmental resistome. In this review, we highlight recent advances in our understanding of horizontal gene transfer of antibiotic resistance genes from the environment to the clinic. Improvements in sequencing technologies coupled with functional metagenomic studies have revealed previously underappreciated diversity in the environmental resistome, and also established novel genetic links to the clinic. Understanding mechanisms of gene exchange becomes vital in controlling the future dissemination of antibiotic resistance.

  6. In vitro activity of fluoroquinolones (gatifloxacin, levofloxacin and trovafloxacin and seven other antibiotics against Streptococcus pneumoniae

    Directory of Open Access Journals (Sweden)

    Nicodemo A.C.

    2001-01-01

    Full Text Available In recent years, the level of resistance of S. pneumoniae to beta-lactam and/or macrolides has increased around the world including some countries in South America. Because of this resistance, it is necessary to test the therapeutic alternatives for treating this pathogen, including the newer quinolones. This study was carried out in order to compare the in vitro activity of fluoroquinolones gatifloxacin, levofloxacin and trovafloxacin, to penicillin G, amoxicillin, amoxicillin-clavulanate, cufuroxime sodium, ceftriaxone, azithromycin and clarithromycin, against 300 strains of S. pneumoniae. Of the 300 samples tested, 18.6% were not susceptible to penicillin (56 strains and 7% (21 strains were resistant to the second generation cephalosporin. Among the macrolides, resistance ranged from 6.7% for clarithromycin to 29.6% for azithromycin. Susceptibility to the newer quinolones was 100% including the 56 strains not susceptible to penicillin. Among the 10 antibiotics evaluated, the fluoroquinolones gatifloxacin, levofloxacin, and trovafloxacin displayed high levels of in vitro activity against S. pneumoniae.

  7. Bactericidal Antibiotics Induce Toxic Metabolic Perturbations that Lead to Cellular Damage

    Directory of Open Access Journals (Sweden)

    Peter Belenky

    2015-11-01

    Full Text Available Understanding how antibiotics impact bacterial metabolism may provide insight into their mechanisms of action and could lead to enhanced therapeutic methodologies. Here, we profiled the metabolome of Escherichia coli after treatment with three different classes of bactericidal antibiotics (β-lactams, aminoglycosides, quinolones. These treatments induced a similar set of metabolic changes after 30 min that then diverged into more distinct profiles at later time points. The most striking changes corresponded to elevated concentrations of central carbon metabolites, active breakdown of the nucleotide pool, reduced lipid levels, and evidence of an elevated redox state. We examined potential end-target consequences of these metabolic perturbations and found that antibiotic-treated cells exhibited cytotoxic changes indicative of oxidative stress, including higher levels of protein carbonylation, malondialdehyde adducts, nucleotide oxidation, and double-strand DNA breaks. This work shows that bactericidal antibiotics induce a complex set of metabolic changes that are correlated with the buildup of toxic metabolic by-products.

  8. Magnetic isotope effect of magnesium (25)Mg on E. coli resistance to antibiotics.

    Science.gov (United States)

    Letuta, U G; Vekker, A S; Kornilova, T A; Gryaznov, A A; Cheplakov, I A

    2016-07-01

    Effects of synergism and antagonism of antibacterial drugs and magnetic isotope of magnesium (25)Mg on antibiotic resistance of bacteria E. coli were discovered. Fourteen antibiotics from seven different groups were tested. The increase in antibiotic resistance in the presence of the ion (25)Mg(2+) was discovered in E. coli cells incubated with quinolones/fluoroquinolones, indicating the inhibiting effect of the magnetic moments of nuclei (25)Mg on DNA synthesis. The change in antibiotic resistance was also detected in bacteria affected by magnesium (25)Mg and certain antibiotics from aminoglycoside and lincosamide groups. PMID:27599512

  9. Diverse modulation of spa transcription by cell wall active antibiotics in Staphylococcus aureus

    DEFF Research Database (Denmark)

    Nielsen, Lene Nørby; Roggenbuck, Michael; Haaber, Jakob Krause;

    2012-01-01

    ABSTRACT: BACKGROUND: The aim of this study was to investigate the effect of various classes of clinically relevant antibiotics at sub-lethal concentrations on virulence gene expression and biofilm formation in Staphylococcus aureus. FINDINGS: LacZ promoter fusions of genes related...... by quantitative real-time PCR. Additionally, we monitored the effect of subinhibitory concentrations of antibiotics on the ability of S. aureus to form biofilm in a microtiter plate assay. The results show that sub-lethal antibiotic concentrations diversely modulate expression of RNAIII, hla and spa. Consistently...

  10. In vitro activities of nisin and nisin derivatives alone and in combination with antibiotics against Staphylococcus biofilms

    Directory of Open Access Journals (Sweden)

    Des eField

    2016-04-01

    Full Text Available The development and spread of pathogenic bacteria that are resistant to the existing catalogue of antibiotics is a major public health threat. Biofilms are complex, sessile communities of bacteria embedded in an organic polymer matrix which serve to further enhance antimicrobial resistance. Consequently, novel compounds and innovative methods are urgently required to arrest the proliferation of drug-resistant infections in both nosocomial and community environments. Accordingly, it has been suggested that antimicrobial peptides could be used as novel natural inhibitors that can be used in formulations with synergistically-acting antibiotics. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many Gram-positive bacteria. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus (MRSA, vancomycin-resistant enterococci (VRE, staphylococci and streptococci associated with bovine mastitis. We have also identified nisin derivatives with an enhanced ability to impair biofilm formation and to reduce the density of established biofilms of methicillin resistant Staphylococcus pseudintermedius (MRSP. The present study was aimed at evaluating the potential of nisin and nisin derivatives to increase the efficacy of conventional antibiotics and to assess the possibility of killing and/or eradicating biofilm-associated cells of a variety of staphylococcal targets. Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284 respectively compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone. Furthermore, the metabolic

  11. In Vitro Activities of Nisin and Nisin Derivatives Alone and In Combination with Antibiotics against Staphylococcus Biofilms

    Science.gov (United States)

    Field, Des; O’ Connor, Rory; Cotter, Paul D.; Ross, R. Paul; Hill, Colin

    2016-01-01

    The development and spread of pathogenic bacteria that are resistant to the existing catalog of antibiotics is a major public health threat. Biofilms are complex, sessile communities of bacteria embedded in an organic polymer matrix which serve to further enhance antimicrobial resistance. Consequently, novel compounds and innovative methods are urgently required to arrest the proliferation of drug-resistant infections in both nosocomial and community environments. Accordingly, it has been suggested that antimicrobial peptides could be used as novel natural inhibitors that can be used in formulations with synergistically acting antibiotics. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many Gram-positive bacteria. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, staphylococci, and streptococci associated with bovine mastitis. We have also identified nisin derivatives with an enhanced ability to impair biofilm formation and to reduce the density of established biofilms of methicillin resistant S. pseudintermedius. The present study was aimed at evaluating the potential of nisin and nisin derivatives to increase the efficacy of conventional antibiotics and to assess the possibility of killing and/or eradicating biofilm-associated cells of a variety of staphylococcal targets. Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone. Furthermore, the metabolic activity of established biofilms treated with nisin

  12. Antibacterial effects of gum kondagogu reduced/stabilized silver nanoparticles in combination with various antibiotics: a mechanistic approach

    Science.gov (United States)

    Rastogi, Lori; Kora, Aruna Jyothi; Sashidhar, R. B.

    2015-06-01

    Gum kondagogu reduced/stabilized silver nanoparticles (GK-AgNPs) were evaluated for their increased antibacterial and antibiofilm activities in combination with various antibiotics (ciprofloxacin, streptomycin and gentamicin) against Gram-positive ( Staphylococcus aureus 25923, Staphylococcus aureus 49834) and Gram-negative ( Escherichia coli 25922, Pseudomonas aeruginosa 27853) bacteria. The micro-broth dilution assay suggested an enhanced antibacterial activity of GK-AgNPs in combination with ciprofloxacin and aminoglycosides (streptomycin and gentamicin) against tested strains. Though the antibacterial activity of GK-AgNPs was found to increase significantly in the presence of antibiotics, the % enhancement was found to depend on both types of antibiotic and bacterial strain. It was also found that GK-AgNPs (1 µg/mL) in combination with various antibiotics at sub-MIC concentrations could inhibit 70 % of the bacterial biofilm formation as compared to respective controls. The enhanced antibacterial activity was due to the increased production of intracellular reactive oxygen species in bacteria when treated with a combination of GK-AgNPs and streptomycin as compared to individual treatment. The increased oxidative stress led to increased membrane damage as assessed by live/dead assay and higher levels of potassium ion release from the cells treated with both silver nanoparticles and streptomycin. The results suggested that the combination of antibiotics with GK-AgNPs has an enhanced antibacterial action. Further, the GK-AgNPs were found to be biocompatible up to a concentration of 2.5 µg/mL as assessed with MTT assay on HeLa cell line. The results suggest that GK-AgNPs could potentially be used as in vivo antibacterial agent in combination with antibiotics to overcome the problem of antibiotic resistance.

  13. New antibiotics for bad bugs: where are we?

    Science.gov (United States)

    Bassetti, Matteo; Merelli, Maria; Temperoni, Chiara; Astilean, Augusta

    2013-01-01

    Bacterial resistance to antibiotics is growing up day by day in both community and hospital setting, with a significant impact on the mortality and morbidity rates and the financial burden that is associated. In the last two decades multi drug resistant microorganisms (both hospital- and community-acquired) challenged the scientific groups into developing new antimicrobial compounds that can provide safety in use according to the new regulation, good efficacy patterns, and low resistance profile. In this review we made an evaluation of present data regarding the new classes and the new molecules from already existing classes of antibiotics and the ongoing trends in antimicrobial development. Infectious Diseases Society of America (IDSA) supported a proGram, called "the '10 × ´20' initiative", to develop ten new systemic antibacterial drugs within 2020. The microorganisms mainly involved in the resistance process, so called the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and enterobacteriaceae) were the main targets. In the era of antimicrobial resistance the new antimicrobial agents like fifth generation cephalosporins, carbapenems, monobactams, β-lactamases inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines active against Gram-positive pathogens, like vancomycin-resistant S. aureus (VRSA) and MRSA, penicillin-resistant streptococci, and vancomycin resistant Enterococcus (VRE) but also against highly resistant Gram-negative organisms are more than welcome. Of these compounds some are already approved by official agencies, some are still in study, but the need of new antibiotics still does not cover the increasing prevalence of antibiotic-resistant bacterial infections. Therefore the management of antimicrobial resistance should also include fostering coordinated actions by all stakeholders, creating policy guidance, support for

  14. THE EFFECT OF GROWTH PARAMETERS ON THE ANTIBIOTIC ACTIVITY AND SPORULATION IN BACILLUS SPP. ISOLATED FROM SOIL

    Directory of Open Access Journals (Sweden)

    Alev Usta

    2013-04-01

    Full Text Available Fifty-two Bacillus strains, which were isolated from different soil samples, were screened for antibiotic properties. The Bacillus strains were checked for antibacterial properties by the cross-streak method against 5 test pathogens, and 25 Bacillus strains had an effect on the test microorganisms. One strain of Bacillus, which exhibited the largest inhibition zone (25 mm against Shigella sonnei, was named Bacillus sp. EA62. The antibacterial activity from Bacillus sp. EA62 was tested in six different culture media against Shigella sonnei using the agar well diffusion method. The best activity medium was selected and used for further studies. The influence of the incubation period, pH, and different glucose and nitrogen concentrations on the antibacterial activity was studied. The optimal conditions for the strongest antibiotic activity were found to be 72 hours (18 mm, pH 7.5 (23 mm, 3% glucose (25 mm, and 0.3% nitrogen concentration (23 mm. Additionally, the relationship between the antibiotic activity and sporulation was investigated. Accordingly, it was determined that the increase of the activity paralleled sporulation.

  15. Characterization of paired mucoid/non-mucoid Pseudomonas aeruginosa isolates from Danish cystic fibrosis patients: antibiotic resistance, beta-lactamase activity and RiboPrinting

    DEFF Research Database (Denmark)

    Ciofu, O; Fussing, V; Bagge, N;

    2001-01-01

    The purpose of this study was to characterize 42 paired mucoid and non-mucoid Danish cystic fibrosis (CF) Pseudomonas aeruginosa isolates collected in 1997, by RiboPrinting, antibiotic susceptibility and beta-lactamase activity. Eight P. aeruginosa isolates collected before 1991 were included for...... before 1991 had an antibiotic susceptibility pattern similar to the 1997 isolates. Despite prolonged and intensive antibiotic treatment, susceptible mucoid isolates were isolated from the CF sputum, possibly because these bacteria are protected from the selective pressure of antibiotics by the resistant...

  16. A Simple Assay to Screen Antimicrobial Compounds Potentiating the Activity of Current Antibiotics

    OpenAIRE

    Junaid Iqbal; Ruqaiyyah Siddiqui; Shahana Urooj Kazmi; Naveed Ahmed Khan

    2013-01-01

    Antibiotic resistance continues to pose a significant problem in the management of bacterial infections, despite advances in antimicrobial chemotherapy and supportive care. Here, we suggest a simple, inexpensive, and easy-to-perform assay to screen antimicrobial compounds from natural products or synthetic chemical libraries for their potential to work in tandem with the available antibiotics against multiple drug-resistant bacteria. The aqueous extract of Juglans regia tree bark was tested a...

  17. Screening for Antibiotic Activity by Miniaturized Cultivation in Micro-Segmented Flow

    Science.gov (United States)

    Zang, Emerson; Tovar, Miguel; Martin, Karin; Roth, Martin

    Despite arduous dedication of the scientific community during the last decades, most screening efforts failed to reveal new antibiotic substances. Droplet-based microfluidics provide a powerful platform to effectively exploit natural metabolic diversity and revitalize the search for new antimicrobials. In this chapter, we explore main requirements to develop and apply droplet-based microfluidic screening strategies for the discovery of novel antibiotics from natural products.

  18. Evaluation of the Antimicrobial Activity of Different Antibiotics Enhanced with Silver-Doped Hydroxyapatite Thin Films

    Directory of Open Access Journals (Sweden)

    Daniela Predoi

    2016-09-01

    Full Text Available The inhibitory and antimicrobial effects of silver particles have been known since ancient times. In the last few years, a major health problem has arisen due to pathogenic bacteria resistance to antimicrobial agents. The antibacterial activities of new materials including hydroxyapatite (HAp, silver-doped hydroxyapatite (Ag:HAp and various types of antibiotics such as tetracycline (T-HAp and T-Ag:HAp or ciprofloxacin (C-HAp and C-Ag:HAp have not been studied so far. In this study we reported, for the first time, the preparation and characterization of various thin films based on hydroxyapatite and silver-doped hydroxyapatite combined with tetracycline or ciprofloxacin. The structural and chemical characterization of hydroxyapatite and silver-doped hydroxyapatite thin films has been evaluated by X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR. The morphological studies of the HAp, Ag:HAp, T-HAp, T-Ag:HAp, C-HAp and C-Ag:HAp thin solid films were performed using scanning electron microscopy (SEM. In order to study the chemical composition of the coatings, energy dispersive X-ray analysis (EDX and glow discharge optical emission spectroscopy (GDOES measurements have been used, obtaining information on the distribution of the elements throughout the film. These studies have confirmed the purity of the prepared hydroxyapatite and silver-doped hydroxyapatite thin films obtained from composite targets containing Ca10−xAgx(PO46(OH2 with xAg = 0 (HAp and xAg = 0.2 (Ag:HAp. On the other hand, the major aim of this study was the evaluation of the antibacterial activities of ciprofloxacin and tetracycline in the presence of HAp and Ag:HAp thin layers against Staphylococcus aureus and Escherichia coli strains. The antibacterial activities of ciprofloxacin and tetracycline against Staphylococcus aureus and Escherichia coli test strains increased in the presence of HAp and Ag:HAp thin layers.

  19. ASSESSMENT OF ANTIMICROBIAL ACTIVITY OF PUNICA GRANATUM AGAINST ANTIBIOTIC-RESISTANT CLOSTRIDIUM PERFRINGENS TYPE (D

    Directory of Open Access Journals (Sweden)

    FRDOOS AL FADEL , SHAZA AL LAHAM, HASSANA CHOUR

    2015-06-01

    Full Text Available The search for new antibiotics and alternative products to solve the increasing number of bacterial resistance to customary antibiotics has become an urgent need. To investigate the effectiveness of the extracts prepared from different parts of Syrian Punica granatum Linn (family Punicaceae, against Clostridium perfringens type (D, which is resistant against many antibiotics, 684 samples were isolated from intestines and livers of death goats by using blood agar, and a selective agar for growing of Clostridium perfringens(SPS agar. The isolated bacteria were typed by using ELISA apparatus. Many parts of Punica granatum was extracted with water, absolute alcohol, then ether by using soxhlet apparatus and rotary evaporator. The Antibiotic susceptibility testing of many antibiotics was conducted by using disc diffusion method in anaerobic atmosphere and break points method. The alcoholic extracts prepared from many parts of punica granatum (pericarp, leaves, flowers, seeds showed different antibacterial effect against Clostridium perfringens type(D,whereas the studied antibiotics had not shown any antibacterial effect, except Clindamycin which showed partial effectiveness. 

  20. In search of alternative antibiotic drugs: Quorum-quenching activity in sponges and their bacterial isolates

    Directory of Open Access Journals (Sweden)

    Kumar eSaurav

    2016-04-01

    Full Text Available Owing to the extensive development of drug resistance in pathogens against the available antibiotic arsenal, antimicrobial resistance is now an emerging major threat to public healthcare. Anti-virulence drugs are a new type of therapeutic agent aiming at virulence factors rather than killing the pathogen, thus providing less selective pressure for evolution of resistance. One promising example of this therapeutic concept targets bacterial quorum sensing (QS, because QS controls many virulence factors responsible for bacterial infections. Marine sponges and their associated bacteria are considered a still untapped source for unique chemical leads with a wide range of biological activities. In the present study, we screened extracts of fourteen sponge species collected from the Red and Mediterranean Sea for their quorum-quenching (QQ potential. Half of the species showed QQ activity in at least 2 out of 3 replicates. Six out of the 14 species were selected for bacteria isolation, to test for QQ activity also in isolates, which, once cultured, represent an unlimited source of compounds. We show that approximately 20% of the isolates showed QQ activity based on a Chromobacterium violaceum CV026 screen, and that the presence or absence of QQ activity in a sponge extract did not co-relate with the abundance of isolates with the same activity from the same sponge species. This can be explained by the unknown source of QQ compounds in sponge-holobionts (host or symbionts, and further by the possible non-symbiotic nature of bacteria isolated from sponges. The potential symbiotic nature of the isolates showing QQ activity was tested according to the distribution and abundance of taxonomically close bacterial Operational Taxonomic Units (OTUs in a dataset including 97 sponge species and 178 environmental samples (i.e., seawater, freshwater and marine sediments. Most isolates were found not to be enriched in sponges, and may simply have been trapped in the

  1. In Search of Alternative Antibiotic Drugs: Quorum-Quenching Activity in Sponges and their Bacterial Isolates.

    Science.gov (United States)

    Saurav, Kumar; Bar-Shalom, Rinat; Haber, Markus; Burgsdorf, Ilia; Oliviero, Giorgia; Costantino, Valeria; Morgenstern, David; Steindler, Laura

    2016-01-01

    Owing to the extensive development of drug resistance in pathogens against the available antibiotic arsenal, antimicrobial resistance is now an emerging major threat to public healthcare. Anti-virulence drugs are a new type of therapeutic agent aiming at virulence factors rather than killing the pathogen, thus providing less selective pressure for evolution of resistance. One promising example of this therapeutic concept targets bacterial quorum sensing (QS), because QS controls many virulence factors responsible for bacterial infections. Marine sponges and their associated bacteria are considered a still untapped source for unique chemical leads with a wide range of biological activities. In the present study, we screened extracts of 14 sponge species collected from the Red and Mediterranean Sea for their quorum-quenching (QQ) potential. Half of the species showed QQ activity in at least 2 out of 3 replicates. Six out of the 14 species were selected for bacteria isolation, to test for QQ activity also in isolates, which, once cultured, represent an unlimited source of compounds. We show that ≈20% of the isolates showed QQ activity based on a Chromobacterium violaceum CV026 screen, and that the presence or absence of QQ activity in a sponge extract did not correlate with the abundance of isolates with the same activity from the same sponge species. This can be explained by the unknown source of QQ compounds in sponge-holobionts (host or symbionts), and further by the possible non-symbiotic nature of bacteria isolated from sponges. The potential symbiotic nature of the isolates showing QQ activity was tested according to the distribution and abundance of taxonomically close bacterial Operational Taxonomic Units (OTUs) in a dataset including 97 sponge species and 178 environmental samples (i.e., seawater, freshwater, and marine sediments). Most isolates were found not to be enriched in sponges and may simply have been trapped in the filtration channels of the

  2. Antibiotics that target protein synthesis.

    Science.gov (United States)

    McCoy, Lisa S; Xie, Yun; Tor, Yitzhak

    2011-01-01

    The key role of the bacterial ribosome makes it an important target for antibacterial agents. Indeed, a large number of clinically useful antibiotics target this complex translational ribonucleoprotein machinery. The majority of these compounds, mostly of natural origin, bind to one of the three key ribosomal sites: the decoding (or A-site) on the 30S, the peptidyl transferase center (PTC) on the 50S, and the peptide exit tunnel on the 50S. Antibiotics that bind the A-site, such as the aminoglycosides, interfere with codon recognition and translocation. Peptide bond formation is inhibited when small molecules like oxazolidinones bind at the PTC. Finally, macrolides tend to block the growth of the amino acid chain at the peptide exit tunnel. In this article, the major classes of antibiotics that target the bacterial ribosome are discussed and classified according to their respective target. Notably, most antibiotics solely interact with the RNA components of the bacterial ribosome. The surge seen in the appearance of resistant bacteria has not been met by a parallel development of effective and broad-spectrum new antibiotics, as evident by the introduction of only two novel classes of antibiotics, the oxazolidinones and lipopeptides, in the past decades. Nevertheless, this significant health threat has revitalized the search for new antibacterial agents and novel targets. High resolution structural data of many ribosome-bound antibiotics provide unprecedented insight into their molecular contacts and mode of action and inspire the design and synthesis of new candidate drugs that target this fascinating molecular machine. PMID:21957007

  3. Induction of a stress response in Lactococcus lactis is associated with a resistance to ribosomally active antibiotics.

    Science.gov (United States)

    Dorrian, James M; Briggs, Deborah A; Ridley, Michael L; Layfield, Robert; Kerr, Ian D

    2011-11-01

    The acquisition of multidrug resistance in bacteria underlies the failure of antimicrobial therapy, and the emergence of pathogens that are resistant to almost the entire armoury of antibiotics. Among the proteins that can mediate or contribute to the drug-resistance profile in Gram-positive bacteria is a subset of ATP-binding cassette proteins that are comprised of a tandem-repeated nucleotide-binding domain. In this study, we expressed one of these NBD(2) proteins, LmrC, in an antibiotic-sensitive Gram-positive host strain (Lactococcus lactis) and demonstrated the acquisition of resistance to ribosomally active antibiotics. Mutation of key catalytic residues suggested that the resistance profile was the result of a cellular response, rather than being a function of the NBD(2) protein itself. This observation was confirmed by 2D SDS/PAGE, which demonstrated that the expression of the NBD(2) protein induced a stress response in L. lactis. A model combining this stress response induction and the acquisition of antibiotic resistance is proposed. PMID:21848804

  4. High frequency ultrasound as a selective advanced oxidation process to remove penicillinic antibiotics and eliminate its antimicrobial activity from water.

    Science.gov (United States)

    Serna-Galvis, Efraim A; Silva-Agredo, Javier; Giraldo-Aguirre, Ana L; Flórez-Acosta, Oscar A; Torres-Palma, Ricardo A

    2016-07-01

    This work studies the sonochemical degradation of a penicillinic antibiotic (oxacillin) in simulated pharmaceutical wastewater. High frequency ultrasound was applied to water containing the antibiotic combined with mannitol or calcium carbonate. In the presence of additives, oxacillin was efficiently removed through sonochemical action. For comparative purposes, the photo-Fenton, TiO2 photocatalysis and electrochemical oxidation processes were also tested. Therefore, the evolution of the antibiotic and its associated antimicrobial activity (AA) were monitored. A high inhibition was found for the other three oxidation processes in the elimination of the antimicrobial activity caused by the additives; while for the ultrasonic treatment, a negligible effect was observed. The sonochemical process was able to completely degrade the antibiotic, generating solutions without AA. In fact, the elimination of antimicrobial activity showed an excellent performance adjusted to exponential kinetic-type decay. The main sonogenerated organic by-products were determined by means of HPLC-MS. Four intermediaries were identified and they have modified the penicillinic structure, which is the moiety responsible for the antimicrobial activity. Additionally, the possible oxacillin sonodegradation mechanism was proposed based on the evolution of the by-products and their chemical structure. Furthermore, the high-frequency ultrasound action over 120 min readily removed oxacillin and eliminated its antimicrobial activity. However, the pollutant was not mineralized even after a long period of ultrasonic irradiation (360 min). Interestingly, the previously sonicated water containing oxacillin and both additives was completely mineralized using non-adapted microorganisms from a municipal wastewater treatment plant. These results show that the sonochemical treatment transformed the initial pollutant into substances that are biotreatable with a typical aerobic biological system. PMID:26964950

  5. ANTIBACTERIAL ACTIVITY OF SOME WILD MEDICAL PLANTS EXTRACT TO ANTIBIOTIC RESISTANT ESCHERICHIA COLI

    Directory of Open Access Journals (Sweden)

    Lukáš Hleba

    2013-02-01

    Full Text Available Antibiotics are probably the most successful family of drugs so far developed for improving human health. Because of increasing resistance to antibiotics of many bacteria, plant extracts and plant compounds are of new interest as antiseptics and antimicrobial agents in medicine. In this study, we researched antimicrobial effects of extracts of some medical plants (Tussilagofarfara, Equisetum arvense, Sambucusnigra, Aesculushippocastanumand Taraxacumofficinale from Slovakia to antibiotic resistant and antibiotic sensitive bacteria isolated from milk of cows and mare, which were breeded in different conditions. Microorganisms which were used in this experiment we isolated from milk from conventional breeding of cows (tenE. coli strains and from ecological breeding of Lipicanmare (tenE. coli strains by sterile cotton swabs. For antibiotic susceptibility testing was used disc diffusion method according by EUCAST. After dried at room temperature we weighed 50 g of crushed medical plants (parts and it were to extract in 400 ml methanol for two weeks at room temperature. For antimicrobial susceptibility testing of medical plants extract blank discs with 6 mm diameter disc diffusion method was used. We determined that all Escherichia coli strains isolated from milk of conventional breeding of cows were resistant to ampicillin and chloramphenicol. We determined that all tested ampicillin and chloramphenicol resistant E. coli strains isolated from conventional breeding of cow showed susceptibility to all used medical plants extracts. In difference, we determined that antibiotic susceptible E. coli strains isolated from ecological breeding of Lipicanmare were susceptible to Tussilagofarfara extract only. From these results we could be conclude some observations, which could be important step in treatment of bacterial infections caused by antibiotic resistant bacteria and it could be important knowledge for treatment of livestock in conventional breeding

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

    OpenAIRE

    Naser Samadi; Rahim Aali; Esrafil Asgari; Hamed Mirhosaeini; Ali Shahriari; Farhad Mahmoodi; Fardin Nouri; Asad Hamdi; Farzad Fanaie; Shahla Yosefi; Saied Dadashi

    2015-01-01

    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...

  7. Polyprenols of Ginkgo biloba Enhance Antibacterial Activity of Five Classes of Antibiotics

    Science.gov (United States)

    Ye, Jianzhong; Zhou, Hao; Chen, Hongxia

    2016-01-01

    Polyprenol (GBP) from Ginkgo biloba Leaves (GBL) is an important lipid with many bioactive effects. The effect of GBP on antibacterial properties of five antibiotics belonging to different classes was through analysis of inhibition halos, MIC, and FIC index. And we studied the time-killing curves and Ca2+ mobilization assay in Staphylococcus aureus cells treated with GBP microemulsion and gentamicin sulfate under MIC/2 conditions. These results showed that the GBP microemulsion (average diameter 90.2 nm) combining with gentamicin sulfate had the highest enhancing antibacterial effect against Staphylococcus aureus, and the MIC value was 33.0 μg/mL. The increase of the antibacterial effect of tested antibiotics was positively correlated with the decrease of the average diameter of GBP microemulsion. Moreover, GBP microemulsion enhanced antibacterial effect and prolonged antibacterial time of GBP combining with gentamicin sulfate against Staphylococcus aureus. GBP microemulsion could enhance the ability of gentamicin inducing an increase in intracellular calcium concentrations to Staphylococcus aureus. GBP microemulsion could help some classes of antibiotics to inhibit or kill bacteria. This study supports the fact that GBP microemulsion obviously can not only reduce the dosage of some classes of antibiotics, but also reduce the frequency of the antibiotic use in vitro. PMID:27642597

  8. A Comprehensive Insight into Tetracycline Resistant Bacteria and Antibiotic Resistance Genes in Activated Sludge Using Next-Generation Sequencing

    OpenAIRE

    Kailong Huang; Junying Tang; Xu-Xiang Zhang; Ke Xu; Hongqiang Ren

    2014-01-01

    In order to comprehensively investigate tetracycline resistance in activated sludge of sewage treatment plants, 454 pyrosequencing and Illumina high-throughput sequencing were used to detect potential tetracycline resistant bacteria (TRB) and antibiotic resistance genes (ARGs) in sludge cultured with different concentrations of tetracycline. Pyrosequencing of 16S rRNA gene revealed that tetracycline treatment greatly affected the bacterial community structure of the sludge. Nine genera cons...

  9. Comparison of the antibiotic activities of Daptomycin, Vancomycin, and the investigational Fluoroquinolone Delafloxacin against biofilms from Staphylococcus aureus clinical isolates.

    Science.gov (United States)

    Siala, Wafi; Mingeot-Leclercq, Marie-Paule; Tulkens, Paul M; Hallin, Marie; Denis, Olivier; Van Bambeke, Françoise

    2014-11-01

    Biofilm-related infections remain a scourge. In an in vitro model of biofilms using Staphylococcus aureus reference strains, delafloxacin and daptomycin were found to be the most active among the antibiotics from 8 different pharmacological classes (J. Bauer, W. Siala, P. M. Tulkens, and F. Van Bambeke, Antimicrob. Agents Chemother. 57:2726-2737, 2013, doi:10.1128/AAC.00181-13). In this study, we compared delafloxacin to daptomycin and vancomycin using biofilms produced by 7 clinical strains (S. aureus epidemic clones CC5 and CC8) in order to rationalize the differences observed between the antibiotics and strains. The effects of the antibiotics on bacterial viability (resazurin reduction assay) and biomass (crystal violet staining) were measured and correlated with the proportion of polysaccharides in the matrix, the local microenvironmental pH (micro-pH), and the antibiotic penetration in the biofilm. At clinically meaningful concentrations, delafloxacin, daptomycin, and vancomycin caused a ≥25% reduction in viability against the biofilms formed by 5, 4, and 3 strains, respectively. The antibiotic penetration within the biofilms ranged from 0.6 to 52% for delafloxacin, 0.2 to 10% for daptomycin, and 0.2 to 1% for vancomycin; for delafloxacin, this was inversely related to the polysaccharide proportion in the matrix. Six biofilms were acidic, explaining the high potency of delafloxacin (lower MICs at acidic pH). Norspermidine and norspermine (disassembling the biofilm matrix) drastically increased delafloxacin potency and efficacy (50% reduction in viability for 6 biofilms at clinically meaningful concentrations) in direct correlation with its increased penetration within the biofilm, while they only modestly improved daptomycin efficacy (50% reduction in viability for 2 biofilms) and penetration, and they showed marginal effects with vancomycin. Delafloxacin potency and efficacy against biofilms are benefited by its penetration into the matrix and the local

  10. Degradation of ciprofloxacin and sulfamethoxazole by ferrous-activated persulfate: implications for remediation of groundwater contaminated by antibiotics.

    Science.gov (United States)

    Ji, Yuefei; Ferronato, Corinne; Salvador, Arnaud; Yang, Xi; Chovelon, Jean-Marc

    2014-02-15

    The wide occurrence of antibiotics in groundwater raised great scientific interest as well as public awareness in recent years due to their potential ability to spread antibiotic resistant gene and pose risk to humans. The present study investigated the ferrous ion (Fe(II)) activated decomposition of persulfate (S2O8(2-)), as a potential in situ chemical oxidation (ISCO) approach, for remediation of groundwater contaminated by antibiotics. Fe(II)-persulfate mediated ciprofloxacin (CIP) degradation was found to be more efficient than sulfamethoxazole (SMX) at near neutral pH (pH6.0), probably due to the higher electric density in CIP molecule and its ability to form complex with Fe(II) as a ligand. Hydroxyl (HO) and sulfate radical (SO4(-)) were determined to be responsible for the degradation of CIP and SMX in Fe(II)-persulfate system by molecular probes. No enhancement in the degradation of CIP was observed when citrate (CA), ethylenediaminetetraacetate (EDTA) and (S,S)-ethylenediamine-N,N'-disuccinate (EDDS) were used as Fe(II) chelating agents in Fe(II)-persulfate system. For SMX, CA and EDTA accelerated the degradation by Fe(II)-persulfate. Degradation of antibiotics in river water matrix was nearly the same as that in Milli-Q water, implying the possibility of using Fe(II)-persulfate for antibiotics depletion under environmentally relevant condition. A comparison of the degradation efficiency of SMX with other sulfonamides and sulfanilic acid indicated that the heterocyclic ring has a large impact on the degradation of sulfonamides. Transformation products of CIP and SMX by Fe(II)-persulfate were analyzed by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) technique. Based on the intermediate products, Fe(II)-persulfate mediated CIP degradation pathways were tentatively proposed.

  11. Prediction Model for 30-Day Hospital Readmissions Among Patients Discharged Receiving Outpatient Parenteral Antibiotic Therapy

    OpenAIRE

    Allison, Genève M.; Muldoon, Eavan G.; Kent, David M.; Paulus, Jessica K.; Ruthazer, Robin; Ren, Aretha; Snydman, David R.

    2013-01-01

    Outpatient parenteral antibiotic therapy (OPAT) is a mainstay of current medical therapy. We developed a 30-day readmission prediction model comprised of age, prior admissions, resistant organisms, and aminoglycoside use. Future work should target OPAT patients at high risk of readmission.

  12. Ribozyme-based aminoglycoside switches of gene expression engineered by genetic selection in S. cerevisiae.

    Science.gov (United States)

    Klauser, Benedikt; Atanasov, Janina; Siewert, Lena K; Hartig, Jörg S

    2015-05-15

    Systems for conditional gene expression are powerful tools in basic research as well as in biotechnology. For future applications, it is of great importance to engineer orthogonal genetic switches that function reliably in diverse contexts. RNA-based switches have the advantage that effector molecules interact immediately with regulatory modules inserted into the target RNAs, getting rid of the need of transcription factors usually mediating genetic control. Artificial riboswitches are characterized by their simplicity and small size accompanied by a high degree of modularity. We have recently reported a series of hammerhead ribozyme-based artificial riboswitches that allow for post-transcriptional regulation of gene expression via switching mRNA, tRNA, or rRNA functions. A more widespread application was so far hampered by moderate switching performances and a limited set of effector molecules available. Here, we report the re-engineering of hammerhead ribozymes in order to respond efficiently to aminoglycoside antibiotics. We first established an in vivo selection protocol in Saccharomyces cerevisiae that enabled us to search large sequence spaces for optimized switches. We then envisioned and characterized a novel strategy of attaching the aptamer to the ribozyme catalytic core, increasing the design options for rendering the ribozyme ligand-dependent. These innovations enabled the development of neomycin-dependent RNA modules that switch gene expression up to 25-fold. The presented aminoglycoside-responsive riboswitches belong to the best-performing RNA-based genetic regulators reported so far. The developed in vivo selection protocol should allow for sampling of large sequence spaces for engineering of further optimized riboswitches. PMID:24871672

  13. 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.

  14. In vitro Synergistic Antimicrobial Activity of Romanian Propolis and Antibiotics against Escherichia coli Isolated from Bovine Mastitis

    Directory of Open Access Journals (Sweden)

    Mihaela NICULAE

    2015-12-01

    Full Text Available The study was aimed to characterize the chemical composition and the antimicrobial activity of Romanian propolis ethanolic extracts (EEP against antibiotic-sensitive and antibiotic-resistant E. coli strains isolated from bovine mastitis. The preliminary antimicrobial screening was performed by a disk diffusion method, followed by determination of minimum inhibitory concentrations (MIC and minimum bactericidal concentrations (MBC based on broth microdilution assay; further, the synergistic action of propolis with antimicrobial drugs was assessed by a disk diffusion method on agar containing subinhibitory concentrations of propolis. For the chemical characterisation of EEP, the flavonoids (flavones/flavonols, flavanones/dihydroflavonols and total phenolics were evaluated by spectrophotometric methods. The phenolic compounds of these extracts were also determined using HPLC. The results indicated for Romanian propolis ethanolic extracts the typical poplar composition profile with flavonoids and phenolic acids as main biological active compounds, with chromatographic analysis data confirmed also spectrophotometrically. In addition, positively correlated with the chemical composition, a strong antimicrobial efficacy was exhibited towards E. coli strains, along with interesting synergistic interaction with antibiotics that can be further investigated to obtain propolis-based formulation with antibacterial properties. Subsequent in vitro and in vivo studies evaluating the safety and efficacy are intended to consider propolis in veterinary therapeutic protocols.

  15. Detection of antibiotic-resistant bacteria endowed with antimicrobial activity from a freshwater lake and their phylogenetic affiliation

    Science.gov (United States)

    Zothanpuia; Passari, Ajit K.; Gupta, Vijai K.

    2016-01-01

    Antimicrobial resistance poses a serious challenge to global public health. In this study, fifty bacterial strains were isolated from the sediments of a freshwater lake and were screened for antibiotic resistance. Out of fifty isolates, thirty-three isolates showed resistance against at least two of the selected antibiotics. Analysis of 16S rDNA sequencing revealed that the isolates belonged to ten different genera, namely Staphylococcus(n = 8), Bacillus(n = 7), Lysinibacillus(n = 4), Achromobacter(n=3), bacterium(n = 3), Methylobacterium(n = 2), Bosea(n = 2), Aneurinibacillus(n = 2), Azospirillum(n = 1), Novosphingobium(n = 1). Enterobacterial repetitive intergenic consensus (ERIC) and BOX-PCR markers were used to study the genetic relatedness among the antibiotic resistant isolates. Further, the isolates were screened for their antimicrobial activity against bacterial pathogens viz., Staphylococcus aureus(MTCC-96), Pseudomonas aeruginosa(MTCC-2453) and Escherichia coli(MTCC-739), and pathogenic fungi viz., Fusarium proliferatum (MTCC-286), Fusarium oxysporum (CABI-293942) and Fusarium oxy. ciceri (MTCC-2791). In addition, biosynthetic genes (polyketide synthase II (PKS-II) and non-ribosomal peptide synthetase (NRPS)) were detected in six and seven isolates, respectively. This is the first report for the multifunctional analysis of the bacterial isolates from a wetland with biosynthetic potential, which could serve as potential source of useful biologically active metabolites. PMID:27330861

  16. A Classroom Demonstration of Garlic Extract and Conventional Antibiotics' Antimicrobial Activity

    Science.gov (United States)

    Ekunsanmi, Toye J.

    2005-01-01

    The Kirby-Bauer method is regularly used to test bacterial susceptibility to antibiotics, and is often employed in the classroom for teaching this concept. In this exercise, additional materials and instructions were given to students for the preparation of garlic extract and loading on blank BBL paper discs. They were further instructed to test…

  17. Discovery, characterization and in vivo activity of pyocin SD2, a protein antibiotic from Pseudomonas aeruginosa.

    Science.gov (United States)

    McCaughey, Laura C; Josts, Inokentijs; Grinter, Rhys; White, Paul; Byron, Olwyn; Tucker, Nicholas P; Matthews, Jacqueline M; Kleanthous, Colin; Whitchurch, Cynthia B; Walker, Daniel

    2016-08-01

    Increasing rates of antibiotic resistance among Gram-negative pathogens such as Pseudomonas aeruginosa means alternative approaches to antibiotic development are urgently required. Pyocins, produced by P. aeruginosa for intraspecies competition, are highly potent protein antibiotics known to actively translocate across the outer membrane of P. aeruginosa. Understanding and exploiting the mechanisms by which pyocins target, penetrate and kill P. aeruginosa is a promising approach to antibiotic development. In this work we show the therapeutic potential of a newly identified tRNase pyocin, pyocin SD2, by demonstrating its activity in vivo in a murine model of P. aeruginosa lung infection. In addition, we propose a mechanism of cell targeting and translocation for pyocin SD2 across the P. aeruginosa outer membrane. Pyocin SD2 is concentrated at the cell surface, via binding to the common polysaccharide antigen (CPA) of P. aeruginosa lipopolysaccharide (LPS), from where it can efficiently locate its outer membrane receptor FpvAI. This strategy of utilizing both the CPA and a protein receptor for cell targeting is common among pyocins as we show that pyocins S2, S5 and SD3 also bind to the CPA. Additional data indicate a key role for an unstructured N-terminal region of pyocin SD2 in the subsequent translocation of the pyocin into the cell. These results greatly improve our understanding of how pyocins target and translocate across the outer membrane of P. aeruginosa. This knowledge could be useful for the development of novel anti-pseudomonal therapeutics and will also support the development of pyocin SD2 as a therapeutic in its own right. PMID:27252387

  18. Efflux pump blockers in Gram-negative bacteria:The new generation of hydantoin based-modulators to improve antibiotic activity

    Directory of Open Access Journals (Sweden)

    Ewa eOtrębska-Machaj

    2016-05-01

    Full Text Available Multidrug resistant (MDR bacteria are an increasing health problem with the shortage of new active antibiotic agents. Among effective mechanisms that contribute to the spread of MDR Gram-negative bacteria are drug efflux pumps that expel clinically important antibiotic classes out of the cell. Drug pumps are attractive targets to restore the susceptibility towards the expelled antibiotics by impairing their efflux activity. Arylhydantoin derivatives were investigated for their potentiation of activities of selected antibiotics described as efflux substrates in Enterobacter aerogenes expressing or not AcrAB pump. Several compounds increased the bacterial susceptibility towards nalidixic acid, chloramphenicol and sparfloxacin and were further pharmacomodulated to obtain a better activity against the AcrAB producing bacteria.

  19. Intracellular activity of the peptide antibiotic NZ2114: studies with Staphylococcus aureus and human THP-1 monocytes, and comparison with daptomycin and vancomycin

    DEFF Research Database (Denmark)

    Brinch, Karoline Sidelmann; Tulkens, Paul M; Van Bambeke, Francoise;

    2010-01-01

    Staphylococcus aureus survives inside eukaryotic cells. Our objective was to assess the activity of NZ2114, a novel peptidic antibiotic, against intracellular S. aureus in comparison with established antistaphylococcal agents acting on the bacterial envelope with a distinct mechanism....

  20. Antibiotic resistance pattern in uropathogens

    Directory of Open Access Journals (Sweden)

    Gupta V

    2002-01-01

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

  1. Critical influence of resistance to streptogramin B-type antibiotics on activity of RP 59500 (quinupristin-dalfopristin) in experimental endocarditis due to Staphylococcus aureus.

    OpenAIRE

    Fantin, B.; Leclercq, R.; Merlé, Y; Saint-Julien, L; Veyrat, C; Duval, J; Carbon, C

    1995-01-01

    In order to determine the microbiological and pharmacokinetic parameters that best predicted the in vivo antistaphylococcal activity of the streptogramin RP 59500 (quinupristin-dalfopristin), we evaluated the activity in rabbit aortic endocarditis of three regimens of quinupristin-dalfopristin against five strains of Staphylococcus aureus with various streptogramin B-type antibiotic resistance phenotypes and susceptible to streptogramin A-type antibiotics. Quinupristin-dalfopristin was as act...

  2. 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.

  3. Determination of aminoglycoside resistance in Staphylococcus aureus by DNA hybridization.

    OpenAIRE

    Dickgiesser, N; Kreiswirth, B N

    1986-01-01

    A method is described for identification of the genes conferring aminoglycoside resistance in Staphylococcus aureus by dot-blot and Southern blot techniques. As radioactive probes, fragments of plasmids pAT48, pUBH2, and pH13, carrying the genes for an aminocyclitol-3'-phosphotransferase, an aminocyclitol-4'-adenylyltransferase, and an aminocyclitol-2''-phosphotransferase-aminocyclitol-6'-acetyltransferase, respectively, were used.

  4. COMBINATIONAL ADMINISTRATION OF AMINOGLYCOSIDES AND LOOP DIURETICS AS AN EFFICIENT STRATEGY TO ESTABLISH DEAFNESS MODELS IN RATS

    Institute of Scientific and Technical Information of China (English)

    CONG Tao; LIU Riyuan; YUAN Shuolong; XU Liangwei; YANG Shiming

    2014-01-01

    It is known that aminoglycoside antibiotics can damage the vestibular and auditory sensory epithelia, and the loop diuretics can enhance the ototoxic effect of aminoglycosides. Previous studies on the synergistic effect of these two types of drugs have used mice, guinea pigs and cats, but not rats. The aim of this study was to determine this synergistic effects in rat cochleae. Rats received intravenous injections of different doses of furosemide and/or intramuscular injections of kanamycin sulfate. Au-ditory brainstem response (ABR), scanning electron microscopy (SEM) and immunocytochemistry were used to determine the effects of drug administration. In the group receiving combined administration of furosemide and kanamycin, the ABR thresh-old showed significant elevation 3 days after drug administration, greater than single drug administration. The hair cells showed various degrees of injury from the apical turn to the basal turn of the cochlea and from the outer hair cells to the inner hair cells. Neuron fibers of the hair cells showed significant loss 7 days after the drug administration, but the number of spiral ganglia did not decrease and supporting cells showed no signs of injury. Our study suggest that combined administration of fu-rosemide and kanamycin has an synergistic ototoxic effect, and can result in hair cell loss and hearing loss in rats.

  5. Cymbopogon citratus protects against the renal injury induced by toxic doses of aminoglycosides in rabbits

    Directory of Open Access Journals (Sweden)

    N Ullah

    2013-01-01

    Full Text Available Renal injury is the most common side-effect of aminoglycosides. These antimicrobial drugs are particularly effective against Gram-negative microorganisms. The present study was conducted to investigate the renal protective activity of Cymbopogon citratus in gentamicin-induced nephrotoxicity. Male rabbits were divided into four groups (n=6 including group 1 (0.9% saline treated, group 2 (80 mg/kg/day gentamicin-treated, group 3 (200 mg/kg/day Cymbopogon citratus treated and group 4 (80 mg/kg/day gentamicin and 200 mg/kg/day Cymbopogon citratus treated. Biochemical kidney functioning parameters, urinary enzymes and histopathological examination were performed. The results of the present study showed that simultaneous administration of Cymbopogon citrates and gentamicin significantly protected alteration in body weight, blood urea nitrogen, serum creatinine, creatinine clearance, serum uric acid, serum electrolytes, urinary volume, urinary protein, urinary lactate dehydrogenase and urinary alkaline phosphatase induced by gentamicin. Histological examination of the kidney also suggested the same. It is concluded from the current study that co-administration of Cymbopogon citratus with gentamicin for 3 weeks successfully prevented renal damage associated with aminoglycosides.

  6. 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

    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......RNA nucleotide at C1404. EfmM uses the methyl group donor S-adenosyl-L-methionine to catalyze formation of m(5)C1404 on the 30S ribosomal subunit, whereas naked 16S rRNA and the 70S ribosome are not substrates. Addition of the 5-methyl to C1404 sterically hinders aminoglycoside binding. Crystallographic......Aminoglycosides are ribosome-targeting antibiotics and a major drug group of choice in the treatment of serious enterococcal infections. Here we show that aminoglycoside resistance in Enterococcus faecium strain CIP 54-32 is conferred by the chromosomal gene efmM, encoding the E. faecium...

  7. Evaluation of Aminoglycoside and Non-Aminoglycoside Compounds for Stop-Codon Readthrough Therapy in Four Lysosomal Storage Diseases.

    Directory of Open Access Journals (Sweden)

    Marta Gómez-Grau

    Full Text Available Nonsense mutations are quite prevalent in inherited diseases. Readthrough drugs could provide a therapeutic option for any disease caused by this type of mutation. Geneticin (G418 and gentamicin were among the first to be described. Novel compounds have been generated, but only a few have shown improved results. PTC124 is the only compound to have reached clinical trials. Here we first investigated the readthrough effects of gentamicin on fibroblasts from one patient with Sanfilippo B, one with Sanfilippo C, and one with Maroteaux-Lamy. We found that ARSB activity (Maroteaux-Lamy case resulted in an increase of 2-3 folds and that the amount of this enzyme within the lysosomes was also increased, after treatment. Since the other two cases (Sanfilippo B and Sanfilippo C did not respond to gentamicin, the treatments were extended with the use of geneticin and five non-aminoglycoside (PTC124, RTC13, RTC14, BZ6 and BZ16 readthrough compounds (RTCs. No recovery was observed at the enzyme activity level. However, mRNA recovery was observed in both cases, nearly a two-fold increase for Sanfilippo B fibroblasts with G418 and around 1.5 fold increase for Sanfilippo C cells with RTC14 and PTC124. Afterwards, some of the products were assessed through in vitro analyses for seven mutations in genes responsible for those diseases and, also, for Niemann-Pick A/B. Using the coupled transcription/translation system (TNT, the best results were obtained for SMPD1 mutations with G418, reaching a 35% recovery at 0.25 μg/ml, for the p.W168X mutation. The use of COS cells transfected with mutant cDNAs gave positive results for most of the mutations with some of the drugs, although to a different extent. The higher enzyme activity recovery, of around two-fold increase, was found for gentamicin on the ARSB p.W146X mutation. Our results are promising and consistent with those of other groups. Further studies of novel compounds are necessary to find those with more

  8. [Bacteriocidal activity of Streptomyces cultures].

    Science.gov (United States)

    Polishchuk, L V; Bambura, O I; Luk'ianchuk, V V

    2012-01-01

    Bacteriocidal activity of metabolites synthesized by 17 plasmid-containing cultures of Streptomyces has been studied. These cultures were isolated from soils of Ukraine with different anthropogenic contamination. The cultures, in their majority (85.3%), synthesized bioactive metabolites, which suppressed growth of microorganisms of different taxonomical groups, pathogenic for people, animals or plants. None of 17 Streptomyces cultures was able to suppress growth of yeasts or Escherichia coli. All 17 investigated cultures of Streptomyces were polyresistant to antibiotics, which were used in medicine and veterinary: makrolide, aminoglycoside, beta-lactam and other groups. Resistance of 8 cultures to the antibiotic thiostrepton, which was widely used in some branches of science, was found. PMID:23088099

  9. Synthesis, optimization, and characterization of silver nanoparticles from Acinetobacter calcoaceticus and their enhanced antibacterial activity when combined with antibiotics

    Directory of Open Access Journals (Sweden)

    Singh R

    2013-11-01

    Full Text Available Richa Singh,1 Priyanka Wagh,1 Sweety Wadhwani,1 Sharvari Gaidhani,2 Avinash Kumbhar,3 Jayesh Bellare,4 Balu Ananda Chopade1 1Department of Microbiology, University of Pune, Pune, Maharashtra, India; 2Institute of Bioinformatics and Biotechnology, University of Pune, Pune, Maharashtra, India; 3Department of Chemistry, University of Pune, Pune, Maharashtra, India; 4Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, India Background: The development of nontoxic methods of synthesizing nanoparticles is a major step in nanotechnology to allow their application in nanomedicine. The present study aims to biosynthesize silver nanoparticles (AgNPs using a cell-free extract of Acinetobacter spp. and evaluate their antibacterial activity. Methods: Eighteen strains of Acinetobacter were screened for AgNP synthesis. AgNPs were characterized using various techniques. Reaction parameters were optimized, and their effect on the morphology of AgNPs was studied. The synergistic potential of AgNPs on 14 antibiotics against seven pathogens was determined by disc-diffusion, broth-microdilution, and minimum bactericidal concentration assays. The efficacy of AgNPs was evaluated as per the minimum inhibitory concentration (MIC breakpoints of the Clinical and Laboratory Standards Institute (CLSI guidelines. Results: Only A. calcoaceticus LRVP54 produced AgNPs within 24 hours. Monodisperse spherical nanoparticles of 8–12 nm were obtained with 0.7 mM silver nitrate at 70°C. During optimization, a blue-shift in ultraviolet-visible spectra was seen. X-ray diffraction data and lattice fringes (d =0.23 nm observed under high-resolution transmission electron microscope confirmed the crystallinity of AgNPs. These AgNPs were found to be more effective against Gram-negative compared with Gram-positive microorganisms. Overall, AgNPs showed the highest synergy with vancomycin in the disc-diffusion assay. For Enterobacter

  10. Effect of Special Rectification Activities of Antibiotics on The Antibiotic Use among The Inpatients%抗菌药物专项整治活动对住院患者抗菌药物应用的影响

    Institute of Scientific and Technical Information of China (English)

    王娟; 陈耀升; 冯玉凤; 王军慈

    2015-01-01

    OBJECTIVE:To investigate the effect of the special antibiotic rectification activities on antibiotic use in the inpatients and evaluate the clinical antibiotic use after policy implementation so as to provide reference for carrying out special rectification.METHODS:Retrospectively, the antibiotic use in the inpatients in our hospital from 2010 to 2014 was analyzed with consumption amount, antibiotic use density ( AUD) , rate of antibiotic use, defined daily cost ( DDC) , medication frequency ( DDDs ) , rate of preventive antibiotic use in patients undergoing type Ⅰ incision operation and rate of pathogen test as the key monitoring indicators, with inpatient antibiotic use before and after the special rectification activities evaluated.RESULTS:Over the 5 years, the rate of antibiotic use, the AUD, the DDC and other indicators showed downward trend, with the number of antibacterial drugs available down from 50 varieties (78 specifications) to 34 varieties (53 specifications), the proportion of antibiotic consumption sum in total drug consumption sum down from 27.7%to 11.3%, the rate of antibiotic use down from 89.5% to 52.1%, AUD down from 69.5 DDD/(100 person per day) to 36.2 DDD/(100 person per day) , rate of pathogen test up year by year and rate of prophylactic antibiotic use in patients undergoing typeⅠincision operation down from 85.6%to 29.7%.The rate of rational antibiotic use in terms of drug varieties in prophylactic use, delivery time and course of treatment etc was up from 11.6% to 82.5%.The choice of prophylactic antibiotic in variety and the drug delivery time were significantly improved with the special rectification activities; however, the course of treatment needs to be standardized.CONCLUSIONS:Special rectification activities on antibiotic use significantly improved the rationality in clinical antibiotic use, however, the limitations of drug varieties of antibiotics, screening of drug resistance and the importance of pathogen test of different

  11. A Comprehensive in vitro and in silico Analysis of Antibiotics that Activate PXR and Induce CYP3A4 in Liver and Intestine

    OpenAIRE

    Yasuda, Kazuto; Ranade, Aarati; Venkataramanan, Raman; Strom, Stephen; Chupka, Jonathan; Ekins, Sean; Schuetz, Erin; Bachmann, Kenneth

    2008-01-01

    We have investigated several in silico and in vitro methods in order to improve our ability to predict potential drug interactions of antibiotics. Our focus was to identify those antibiotics that activate PXR and induce CYP3A4 in human hepatocytes and intestinal cells. Human PXR activation was screened using reporter assays in HepG2 cells, kinetic measurements of PXR activation were made in DPX-2 cells, and induction of CYP3A4 expression and activity was verified by quantitative PCR, immunobl...

  12. Modulation of the Antibiotic Activity by Extracts from Amburana cearensis A. C. Smith and Anadenanthera macrocarpa (Benth. Brenan

    Directory of Open Access Journals (Sweden)

    Fernando G. Figueredo

    2013-01-01

    Full Text Available The aim of this study was to verify the possible interactions between ethanol extracts of Amburana cearensis A. C. Smith and Anadenanthera macrocarpa (Benth. Brenan, combined with six antimicrobial drugs against multiresistant strains of Staphylococcus aureus and Escherichia coli isolated from humans. The antibacterial activity of the extracts was determined using the minimum inhibitory concentration (MIC. The microdilution assay was performed to verify the interactions between the natural products and the antibiotics using a subinhibitory concentration. The activity of amikacin associated with the extract of Anadenanthera macrocarpa against EC 27 was enhanced, demonstrating an MIC reduction from 128 to 4 μg/mL. Among the β-lactams, no potentiation on its activity was observed, with exception to the antagonism of the natural products with ampicillin against S. aureus 358.

  13. Indole Based Weapons to Fight Antibiotic Resistance: A Structure-Activity Relationship Study.

    Science.gov (United States)

    Lepri, Susan; Buonerba, Federica; Goracci, Laura; Velilla, Irene; Ruzziconi, Renzo; Schindler, Bryan D; Seo, Susan M; Kaatz, Glenn W; Cruciani, Gabriele

    2016-02-11

    Antibiotic resistance represents a worldwide concern, especially regarding the outbreak of methicillin-resistant Staphylococcus aureus, a common cause for serious skin and soft tissues infections. A major contributor to Staphylococcus aureus antibiotic resistance is the NorA efflux pump, which is able to extrude selected antibacterial drugs and biocides from the membrane, lowering their effective concentrations. Thus, the inhibition of NorA represents a promising and challenging strategy that would allow recycling of substrate antimicrobial agents. Among NorA inhibitors, the indole scaffold proved particularly effective and suitable for further optimization. In this study, some unexplored modifications on the indole scaffold are proposed. In particular, for the first time, substitutions at the C5 and N1 positions have been designed to give 48 compounds, which were synthesized and tested against norA-overexpressing S. aureus. Among them, 4 compounds have NorA IC50 values lower than 5.0 μM proving to be good efflux pump inhibitor (EPI) candidates. In addition, preliminary data on their ADME (absorption, distribution, metabolism, and excretion) profile is reported. PMID:26757340

  14. The sigma factor sigma s affects antibiotic production and biological control activity of Pseudomonas fluorescens Pf-5.

    Science.gov (United States)

    Sarniguet, A; Kraus, J; Henkels, M D; Muehlchen, A M; Loper, J E

    1995-12-19

    Pseudomonas fluorescens Pf-5, a rhizosphere-inhabiting bacterium that suppresses several soilborne pathogens of plants, produces the antibiotics pyrrolnitrin, pyoluteorin, and 2,4-diacetylphloroglucinol. A gene necessary for pyrrolnitrin production by Pf-5 was identified as rpoS, which encodes the stationary-phase sigma factor sigma s. Several pleiotropic effects of an rpoS mutation in Escherichia coli also were observed in an RpoS- mutant of Pf-5. These included sensitivities of stationary-phase cells to stresses imposed by hydrogen peroxide or high salt concentration. A plasmid containing the cloned wild-type rpoS gene restored pyrrolnitrin production and stress tolerance to the RpoS- mutant of Pf-5. The RpoS- mutant overproduced pyoluteorin and 2,4-diacetyl-phloroglucinol, two antibiotics that inhibit growth of the phytopathogenic fungus Pythium ultimum, and was superior to the wild type in suppression of seedling damping-off of cucumber caused by Pythium ultimum. When inoculated onto cucumber seed at high cell densities, the RpoS- mutant did not survive as well as the wild-type strain on surfaces of developing seedlings. Other stationary-phase-specific phenotypes of Pf-5, such as the production of cyanide and extracellular protease(s) were expressed by the RpoS- mutant, suggesting that sigma s is only one of the sigma factors required for the transcription of genes in stationary-phase cells of P. fluorescens. These results indicate that a sigma factor encoded by rpoS influences antibiotic production, biological control activity, and survival of P. fluorescens on plant surfaces. PMID:8618880

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

    Directory of Open Access Journals (Sweden)

    N Perumal

    2016-01-01

    Full Text Available 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.

  16. Utilisation of antibiotic therapy in community practice.

    LENUS (Irish Health Repository)

    McGowan, B

    2008-10-01

    The aim of the study was to identify outpatient antibiotic consumption between Jan 2000 and Dec 2005 through analysis of the HSE-Primary Care Reimbursement Services (PCRS) database as part of the Surveillance of Antimicrobial Resistance in Ireland (SARI) project. Total antibiotic consumption on the PCRS scheme between January 2000 and December 2005 expressed in Defined Daily Dose per 1000 PCRS inhabitants per day increased by 26%. The penicillin group represents the highest consumption accounting for approximately 50% of the total outpatient antibiotic use. Total DIDs for this group increased by 25% between 2000 and 2005. Co-amoxiclav and amoxicillin account for 80% of the total consumption of this group of anti-infectives. With the exception of aminoglycosides and sulfonamides which demonstrated a decrease in DID consumption of 47% and 8% respectively, all other groups of anti-infectives had an increase in DID consumption of greater than 25% during the study period. Antibiotic prescribing data is a valuable tool for assessing public health strategies aiming to optimise antibiotic prescribing.

  17. The bactericidal activity of β-lactam antibiotics is increased by metabolizable sugar species

    DEFF Research Database (Denmark)

    Thorsing, Mette; Bentin, Thomas; Givskov, Michael;

    2015-01-01

    Here, the influence of metabolizable sugars on the susceptibility of Escherichia coli to β-lactam antibiotics was investigated. Notably, monitoring growth and survival of mono- and combination-treated planktonic cultures showed a 1000- to 10 000-fold higher antibacterial efficacy of carbenicillin...... and cefuroxime in the presence of certain sugars, whereas other metabolites had no effect on β-lactam sensitivity. This effect was unrelated to changes in growth rate. Light microscopy and flow cytometry profiling revealed that bacterial filaments, formed due to β-lactam-mediated inhibition of cell division......, rapidly appeared upon β-lactam mono-treatment and remained stable for up to 18 h. The presence of metabolizable sugars in the medium did not change the rate of filamentation, but led to lysis of the filaments within a few hours. No lysis occurred in E. coli mutants unable to metabolize the sugars, thus...

  18. 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. PMID:27472455

  19. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Linke; Na, Guangshui [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Siyu [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Kai [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Peng, E-mail: pzhang@nmemc.org.cn [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Ren, Honglei; Yao, Ziwei [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China)

    2015-09-15

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (t{sub d,E}) and hydroxyl-radical oxidation half-lives (t{sub ·OH,E}) in sunlit surface waters. The t{sub d,E} values range from 0.56 min to 28.8 min at 45° N latitude, whereas t{sub ·OH,E} ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways.

  20. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    International Nuclear Information System (INIS)

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (td,E) and hydroxyl-radical oxidation half-lives (t·OH,E) in sunlit surface waters. The td,E values range from 0.56 min to 28.8 min at 45° N latitude, whereas t·OH,E ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways

  1. A Comprehensive Insight into Tetracycline Resistant Bacteria and Antibiotic Resistance Genes in Activated Sludge Using Next-Generation Sequencing

    Directory of Open Access Journals (Sweden)

    Kailong Huang

    2014-06-01

    Full Text Available In order to comprehensively investigate tetracycline resistance in activated sludge of sewage treatment plants, 454 pyrosequencing and Illumina high-throughput sequencing were used to detect potential tetracycline resistant bacteria (TRB and antibiotic resistance genes (ARGs in sludge cultured with different concentrations of tetracycline. Pyrosequencing of 16S rRNA gene revealed that tetracycline treatment greatly affected the bacterial community structure of the sludge. Nine genera consisting of Sulfuritalea, Armatimonas, Prosthecobacter, Hyphomicrobium, Azonexus, Longilinea, Paracoccus, Novosphingobium and Rhodobacter were identified as potential TRB in the sludge. Results of qPCR, molecular cloning and metagenomic analysis consistently indicated that tetracycline treatment could increase both the abundance and diversity of the tet genes, but decreased the occurrence and diversity of non-tetracycline ARG, especially sulfonamide resistance gene sul2. Cluster analysis showed that tetracycline treatment at subinhibitory concentrations (5 mg/L was found to pose greater effects on the bacterial community composition, which may be responsible for the variations of the ARGs abundance. This study indicated that joint use of 454 pyrosequencing and Illumina high-throughput sequencing can be effectively used to explore ARB and ARGs in the environment, and future studies should include an in-depth investigation of the relationship between microbial community, ARGs and antibiotics in sewage treatment plant (STP sludge.

  2. 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...

  3. Development of antibiotic resistance in Pseudomonas aeruginosa during two decades of antipseudomonal treatment at the Danish CF Center

    DEFF Research Database (Denmark)

    Ciofu, O; Giwercman, B; Pedersen, S S;

    1994-01-01

    was found between the MIC and the number of antipseudomonal courses of antibiotics. The proportion of resistant in vivo selected P. aeruginosa strains, presumed to be stably derepressed producers of chromosomal beta-lactamase, also increased significantly during the period studied. Our results confirm...... that the beta-lactamase production is an important mechanism of antibiotic resistance in P. aeruginosa.......At the Danish CF Center patients with chronic Pseudomonas aeruginosa lung infection were treated 3-4 times a year (from 1976) with a 2-week intravenous antipseudomonal course which included preferentially an aminoglycoside and a beta-lactam antibiotic. We investigated the development of antibiotic...

  4. Environmental pollution by antibiotics and by antibiotic resistance determinants

    International Nuclear Information System (INIS)

    Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations. - The article reviews the current knowledge on the effects that pollution by antibiotics and antibiotic resistance genes may have for the microbiosphere.

  5. Environmental pollution by antibiotics and by antibiotic resistance determinants

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jose Luis, E-mail: jlmtnez@cnb.csic.e [Departamento de Biotecnologia Microbiana, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Darwin 3, Cantoblanco, 28049 Madrid, and CIBERESP (Spain)

    2009-11-15

    Antibiotics are among the most successful drugs used for human therapy. However, since they can challenge microbial populations, they must be considered as important pollutants as well. Besides being used for human therapy, antibiotics are extensively used for animal farming and for agricultural purposes. Residues from human environments and from farms may contain antibiotics and antibiotic resistance genes that can contaminate natural environments. The clearest consequence of antibiotic release in natural environments is the selection of resistant bacteria. The same resistance genes found at clinical settings are currently disseminated among pristine ecosystems without any record of antibiotic contamination. Nevertheless, the effect of antibiotics on the biosphere is wider than this and can impact the structure and activity of environmental microbiota. Along the article, we review the impact that pollution by antibiotics or by antibiotic resistance genes may have for both human health and for the evolution of environmental microbial populations. - The article reviews the current knowledge on the effects that pollution by antibiotics and antibiotic resistance genes may have for the microbiosphere.

  6. Selection of antibiotic resistance at very low antibiotic concentrations.

    Science.gov (United States)

    Sandegren, Linus

    2014-05-01

    Human use of antibiotics has driven the selective enrichment of pathogenic bacteria resistant to clinically used drugs. Traditionally, the selection of resistance has been considered to occur mainly at high, therapeutic levels of antibiotics, but we are now beginning to understand better the importance of selection of resistance at low levels of antibiotics. The concentration of an antibiotic varies in different body compartments during treatment, and low concentrations of antibiotics are found in sewage water, soils, and many water environments due to natural production and contamination from human activities. Selection of resistance at non-lethal antibiotic concentrations (below the wild-type minimum inhibitory concentration) occurs due to differences in growth rate at the particular antibiotic concentration between cells with different tolerance levels to the antibiotic. The minimum selective concentration for a particular antibiotic is reached when its reducing effect on growth of the susceptible strain balances the reducing effect (fitness cost) of the resistance determinant in the resistant strain. Recent studies have shown that resistant bacteria can be selected at concentrations several hundred-fold below the lethal concentrations for susceptible cells. Resistant mutants selected at low antibiotic concentrations are generally more fit than those selected at high concentrations but can still be highly resistant. The characteristics of selection at low antibiotic concentrations, the potential clinical problems of this mode of selection, and potential solutions will be discussed.

  7. 3 Certain Shell Hospital Inpatient Antibiotic Uses are Analysed%某三甲医院住院病人抗生素利用分析

    Institute of Scientific and Technical Information of China (English)

    刘伟卿

    2002-01-01

    Objective We appraise the application condition of 3 certain shell hospital antibiotics. Methods According to medicine, we use research method. As the 280 certain courtyard regular inpatients of May 2001 use the condition of antibiotic,investigate. With the survey that DDD studies as medicine use, we worth. Is judgement doctor with DUI reasonable use the standard of medicine? Results 185 examples are used antibiotic, take 66.07%. With penicillins, Quinolones and Aminoglycosides use count frequently highest. Before locating in, 5 antibiotics are in proper order. Penicillin G, Clindamycin,Amikacin, Sodium Cefotaxime, and Ciprofloxacin. Conclusions The most antibiotic DUI ≤ 1, whole, the application ofantibiotic is reasonable.

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

    Energy Technology Data Exchange (ETDEWEB)

    El-Didamony, A. M.; Ghoneim, A. K.; Telebany, A. M. [Zagazig University, Zagazig (Egypt); Amin, A. S. [Banha University, Banha (Egypt)

    2006-08-15

    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{sub 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{sup -1} for neomycin and streptomycin, respectively. The apparent molar absorptivity and sandell sensitivity values are in the range 5.47-6.20x10{sup 4}, 2.35-2.91x10{sup 5} L mol{sup -1} cm{sup -1} and 7.57-8.59, 5.01-6.2 ng cm{sup -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.

  9. Rapid and liquid-based selection of genetic switches using nucleoside kinase fused with aminoglycoside phosphotransferase.

    Directory of Open Access Journals (Sweden)

    Masahiro Tominaga

    Full Text Available The evolutionary design of genetic switches and circuits requires iterative rounds of positive (ON- and negative (OFF- selection. We previously reported a rapid OFF selection system based on the kinase activity of herpes simplex virus thymidine kinase (hsvTK on the artificial mutator nucleoside dP. By fusing hsvTK with the kanamycin resistance marker aminoglycoside-(3'-phosphotransferase (APH, we established a novel selector system for genetic switches. Due to the bactericidal nature of kanamycin and nucleoside-based lethal mutagenesis, both positive and negative selection could be completed within several hours. Using this new selector system, we isolated a series of homoserine lactone-inducible genetic switches with different expression efficiencies from libraries of the Vibrio fischeri lux promoter in two days, using only liquid handling.

  10. Imipenem-cilastatin sodium, a broad-spectrum carbapenem antibiotic combination.

    Science.gov (United States)

    Pastel, D A

    1986-09-01

    The chemistry, antimicrobial spectrum, mechanism of action, pharmacology and pharmacokinetics, clinical use, adverse effects, dosage and administration, place in therapy, cost-effectiveness, and formulary considerations of imipenem-cilastatin sodium are reviewed. Imipenem is the first carbapenem antibiotic of the thienamycin class to be used clinically. Imipenem has the widest spectrum of antimicrobial activity of currently available beta-lactam agents and, in contrast to other beta-lactam antibiotics, lacks cross resistance with recently introduced extended-spectrum penicillins and third-generation cephalosporins. Against gram-positive and gram-negative aerobic and anaerobic organisms, imipenem demonstrates excellent activity. Pseudomonas maltophilia, some strains of Pseudomonas cepacia, and Streptococcus faecium are resistant. Strains of methicillin-resistant staphylococci should also be considered resistant to imipenem. For clinical use imipenem is coadministered in equal parts with cilastatin. Cilastatin is a renal dehydropeptidase inhibitor that inhibits the metabolism of imipenem by renal brush-border enzymes, thus increasing imipenem concentrations in urine. Imipenem-cilastatin is administered by the intravenous route only. The adverse reaction profile of imipenem-cilastatin is similar to t that of other beta-lactam antibiotics. Recommended dosage reductions appropriate for renal impairment should be guided by periodic assessments of renal function, with close adherence to recommended dosage schedules, particularly among patients who are predisposed to seizures or receiving anticonvulsant medication. Imipenem-cilastatin performed well in both comparative and noncomparative trials of clinical efficacy and safety. For infections with multiple organisms (e.g., pelvic, intra-abdominal, or soft-tissue infections), imipenem-cilastatin may be a cost-effective and less toxic single-agent alternative to "standard" combination (e.g., aminoglycoside-penicillin plus an

  11. Conjugative DNA transfer induces the bacterial SOS response and promotes antibiotic resistance development through integron activation.

    Directory of Open Access Journals (Sweden)

    Zeynep Baharoglu

    2010-10-01

    Full Text Available Conjugation is one mechanism for intra- and inter-species horizontal gene transfer among bacteria. Conjugative elements have been instrumental in many bacterial species to face the threat of antibiotics, by allowing them to evolve and adapt to these hostile conditions. Conjugative plasmids are transferred to plasmidless recipient cells as single-stranded DNA. We used lacZ and gfp fusions to address whether conjugation induces the SOS response and the integron integrase. The SOS response controls a series of genes responsible for DNA damage repair, which can lead to recombination and mutagenesis. In this manuscript, we show that conjugative transfer of ssDNA induces the bacterial SOS stress response, unless an anti-SOS factor is present to alleviate this response. We also show that integron integrases are up-regulated during this process, resulting in increased cassette rearrangements. Moreover, the data we obtained using broad and narrow host range plasmids strongly suggests that plasmid transfer, even abortive, can trigger chromosomal gene rearrangements and transcriptional switches in the recipient cell. Our results highlight the importance of environments concentrating disparate bacterial communities as reactors for extensive genetic adaptation of bacteria.

  12. Montmorillonite enhanced ciprofloxacin transport in saturated porous media with sorbed ciprofloxacin showing antibiotic activity

    Science.gov (United States)

    Chen, Hao; Gao, Bin; Yang, Liu-Yan; Ma, Lena Q.

    2015-02-01

    Antibiotic ciprofloxacin (CIP) is immobile in the subsurface but it has been frequently detected in the aquatic system. Therefore it is important to investigate the factors impacting CIP's mobilization in aquifer. Laboratory columns packed with sand were used to test colloid-facilitated CIP transport by 1) using kaolinite or montmorillonite to mobilize presorbed-CIP in a column or 2) co-transporting with CIP by pre-mixing them before transport. The Langmuir model showed that CIP sorption by montmorillonite (23 g kg- 1) was 100 times more effective than sand or kaolinite. Even with strong CIP complexation ability to Fe/Al coating on sand surface, montmorillonite promoted CIP transport, but not kaolinite. All presorbed-CIP by sand was mobilized by montmorillonite after 3 pore volumes through co-transporting of CIP with montmorillonite. The majority of CIP was fixed onto the montmorillonite interlayer but still showed inhibition of bacteria growth. Our results suggested that montmorillonite with high CIP sorption ability can act as a carrier to enhance CIP's mobility in aquifer.

  13. The effect of systemic antibiotics administered during the active phase of non-surgical periodontal therapy or after the healing phase: a systematic review

    Directory of Open Access Journals (Sweden)

    Aretuza FRITOLI

    2015-06-01

    Full Text Available Objective The aim of this systematic review was to compare the clinical effectiveness of systemic antibiotics administered in the active stage of periodontal treatment or after the healing phase. Material and Methods An electronic search was performed in the databases EMBASE, MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA statement. A manual search of the reference list of selected studies and of review articles was also performed up to November 2013. Randomized Clinical Trials (RCT that evaluated the systemic administration of antibiotics as adjuvants to scaling and root planning (SRP at different phases of periodontal treatment were included. Systematic reviews and studies that evaluated subjects with systemic diseases and those that used subantimicrobial doses of antibiotics were excluded. Results The initial search identified 1,039 articles, of which seven were selected, and only one met the inclusion criteria. This study showed that subjects taking metronidazole and amoxicillin at the initial phase of treatment exhibited statistically significantly greater reduction in pocket depth and gain in clinical attachment level in initially deep sites (PD≥7 mm than subjects taking antibiotics after healing (p<0.05. This comparison was conducted 2 months after antibiotic intake, at the healing phase. Conclusion To date, only one short-term RCT has directly compared different moments of systemic antibiotics administration, as adjuncts to SRP, in the treatment of periodontitis. Although the results of this study suggested some benefits for antibiotics intake during the active phase of therapy, these findings need to be confirmed by larger placebo-controlled randomized clinical trials with longer follow-up periods.

  14. Staphylococcus aureus Alters Growth Activity, Autolysis, and Antibiotic Tolerance in a Human Host-Adapted Pseudomonas aeruginosa Lineage

    DEFF Research Database (Denmark)

    Frydenlund Michelsen, Charlotte; Christensen, Anne-Mette; Bojer, Martin Saxtorph;

    2014-01-01

    Interactions among members of polymicrobial infections or between pathogens and the commensal flora may determine disease outcomes. Pseudomonas aeruginosa and Staphylococcus aureus are important opportunistic human pathogens and are both part of the polymicrobial infection communities in human....... aeruginosa DK2 strains outcompeted S. aureus during coculture on agar plates, we found that later P. aeruginosa DK2 strains showed a commensal-like interaction, where S. aureus was not inhibited by P. aeruginosa and the growth activity of P. aeruginosa was enhanced in the presence of S. aureus. This effect...... is mediated by one or more extracellular S. aureus proteins greater than 10 kDa, which also suppressed P. aeruginosa autolysis and prevented killing by clinically relevant antibiotics through promoting small-colony variant (SCV) formation. The commensal interaction was abolished with S. aureus strains mutated...

  15. A conformational switch in the active site of BT_2972, a methyltransferase from an antibiotic resistant pathogen B. thetaiotaomicron.

    Directory of Open Access Journals (Sweden)

    Veerendra Kumar

    Full Text Available Methylation is one of the most common biochemical reactions involved in cellular and metabolic functions and is catalysed by the action of methyltransferases. Bacteroides thetaiotaomicron is an antibiotic-resistant bacterium that confers resistance through methylation, and as yet, there is no report on the structure of methyltransferases from this bacterium. Here, we report the crystal structure of an AdoMet-dependent methyltransferase, BT_2972 and its complex with AdoMet and AdoHcy for B. thetaiotaomicron VPI-5482 strain along with isothermal titration calorimetric assessment of the binding affinities. Comparison of the apo and complexed BT_2972 structures reveals a significant conformational change between open and closed forms of the active site that presumably regulates the association with cofactors and may aid interaction with substrate. Together, our analysis suggests that BT_2972 is a small molecule methyltransferase and might catalyze two O-methylation reaction steps involved in the ubiquinone biosynthesis pathway.

  16. A conformational switch in the active site of BT_2972, a methyltransferase from an antibiotic resistant pathogen B. thetaiotaomicron.

    Science.gov (United States)

    Kumar, Veerendra; Sivaraman, J

    2011-01-01

    Methylation is one of the most common biochemical reactions involved in cellular and metabolic functions and is catalysed by the action of methyltransferases. Bacteroides thetaiotaomicron is an antibiotic-resistant bacterium that confers resistance through methylation, and as yet, there is no report on the structure of methyltransferases from this bacterium. Here, we report the crystal structure of an AdoMet-dependent methyltransferase, BT_2972 and its complex with AdoMet and AdoHcy for B. thetaiotaomicron VPI-5482 strain along with isothermal titration calorimetric assessment of the binding affinities. Comparison of the apo and complexed BT_2972 structures reveals a significant conformational change between open and closed forms of the active site that presumably regulates the association with cofactors and may aid interaction with substrate. Together, our analysis suggests that BT_2972 is a small molecule methyltransferase and might catalyze two O-methylation reaction steps involved in the ubiquinone biosynthesis pathway. PMID:22140448

  17. 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.

  18. Technological characterisation, antibiotic susceptibility and antimicrobial activity of wild-type Leuconostoc strains isolated from North Italian traditional cheeses.

    Science.gov (United States)

    Morandi, Stefano; Cremonesi, Paola; Silvetti, Tiziana; Brasca, Milena

    2013-11-01

    Genotypic and technological properties, antibiotic susceptibility and antimicrobial activity of 35 Leuconostoc strains, isolated from different Italian raw milk cheeses, were investigated. RAPD-PCR was used to study genetic variability and to distinguish closely related strains. The results showed a high degree of heterogeneity among isolates. All the strains had weak acidifying activity and showed low proteolytic and lipolytic activities. Reduction activity, was generally low. All the Leuconostoc were susceptible to ampicillin, mupirocin, erythromycin, quinupristin/dalfopristin and tetracycline. Many strains were classified as resistant to oxacillin, ciprofloxacin and nitrofurantonin, while all isolates were found resistant to vancomycin. PCR-based detection did not identify any of the common genetic determinants for vancomycin (vanA, vanB, vanC1, vanC2, vanC3, vanD, vanE, vanG) or erythromycin (ermB and ermC). Tetracycline resistance genes were detected in 25 tetracycline susceptible strains, the most frequent one being tetM. One strain, belonging to Ln. pseudomesenteroides species, was positive for the presence of the int gene of the Tn916/Tn1545 trasposon family. This is the first time the conjugative transposon Tn916 has been detected inside the Leuconostoc species. All strains showed antimicrobial activity against Enterococcus faecalis and Ent. faecium. The presence of genes encoding amino-acid decarboxylases (hdc and tdc) was not detected. Some strains are interesting in view of their use in cheese production as starter and non starter cultures. PMID:24067095

  19. Extracellular DNA chelates cations and induces antibiotic resistance in Pseudomonas aeruginosa biofilms.

    Directory of Open Access Journals (Sweden)

    Heidi Mulcahy

    2008-11-01

    Full Text Available Biofilms are surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, bacterial polysaccharides and proteins, which are up to 1000-fold more antibiotic resistant than planktonic cultures. To date, extracellular DNA has been shown to function as a structural support to maintain Pseudomonas aeruginosa biofilm architecture. Here we show that DNA is a multifaceted component of P. aeruginosa biofilms. At physiologically relevant concentrations, extracellular DNA has antimicrobial activity, causing cell lysis by chelating cations that stabilize lipopolysaccharide (LPS and the outer membrane (OM. DNA-mediated killing occurred within minutes, as a result of perturbation of both the outer and inner membrane (IM and the release of cytoplasmic contents, including genomic DNA. Sub-inhibitory concentrations of DNA created a cation-limited environment that resulted in induction of the PhoPQ- and PmrAB-regulated cationic antimicrobial peptide resistance operon PA3552-PA3559 in P. aeruginosa. Furthermore, DNA-induced expression of this operon resulted in up to 2560-fold increased resistance to cationic antimicrobial peptides and 640-fold increased resistance to aminoglycosides, but had no effect on beta-lactam and fluoroquinolone resistance. Thus, the presence of extracellular DNA in the biofilm matrix contributes to cation gradients, genomic DNA release and inducible antibiotic resistance. DNA-rich environments, including biofilms and other infection sites like the CF lung, are likely the in vivo environments where extracellular pathogens such as P. aeruginosa encounter cation limitation.

  20. Constitutive presence of antibiotic resistance genes within the bacterial community of a large subalpine lake.

    Science.gov (United States)

    Di Cesare, Andrea; Eckert, Ester M; Teruggi, Alessia; Fontaneto, Diego; Bertoni, Roberto; Callieri, Cristiana; Corno, Gianluca

    2015-08-01

    The fate of antibiotic resistance genes (ARGs) in environmental microbial communities is of primary concern as prodromal of a potential transfer to pathogenic bacteria. Although of diverse origin, the persistence of ARGs in aquatic environments is highly influenced by anthropic activities, allowing potential control actions in well-studied environments. However, knowledge of abundance and space-time distribution of ARGs in ecosystems is still scarce. Using quantitative real-time PCR, we investigated the presence and the abundance of twelve ARGs (against tetracyclines, β-lactams, aminoglycosides, quinolones and sulphonamides) at different sampling sites, depths and seasons, in Lake Maggiore, a large subalpine lake, and in the area of its watershed. We then evaluated the correlation between each ARG and a number of ecological parameters in the water column in the deepest part of the lake. Our results suggest the constitutive presence of at least four ARGs within the bacterial community with a high proportion of bacteria potentially resistant to tetracyclines and sulphonamides. The presence of these ARGs was independent of the total bacterial density and temperature. The dynamics of tet(A) and sulII genes were, however, positively correlated with dissolved oxygen and negatively to chlorophyll a, suggesting that the resistant microbes inhabit specific niches. These observations indicate that the lake is a reservoir of antibiotic resistances, highlighting the need of a deeper understanding of the sources of ARGs and the factors allowing their persistence in waters. PMID:26118321

  1. EF-Tu from the enacyloxin producing Frateuria W-315 strain: Structure/activity relationship and antibiotic resistance.

    Science.gov (United States)

    Créchet, Jean-Bernard; Malosse, Christian; Hountondji, Codjo

    2016-08-01

    In this report, we have demonstrated that the poly(U)-dependent poly(Phe) synthesis activity of elongator factor Tu (EF-Tu) from the enacyloxin producing strain Frateuria sp. W-315 is inhibited by the antibiotic similarly to that of Escherichia coli EF-Tu. The inhibitory effect of enacyloxin observed in a purified system was the same as that obtained with an S30 extract from E. coli or Frateuria sp. W-315, respectively, suggesting that antibiotic resistance of enacyloxin producing Frateuria sp. W-315 is not due neither to EF-Tu nor to other components of the translation machinery but to a still unknown mechanism. The EF-Tu gene, as PCR amplified from Frateuria W-315 genomic DNA and sequenced represented an ORF of 1191 nucleotides corresponding to 396 amino acids. This protein is larger than the product of tufA from E. coli by only two amino acid residues. Alignment of the amino acid sequence of EF-Tu from E. coli with those of Frateuria and Ralstonia solanacearum indicates on average 80% identical amino acid residues and 9.7% conservative replacements between EF-Tu Frateuria and EF-Tu E. coli, on one hand, and 97% identity and 1.7% conservative replacement between EF-Tu Frateuria and EF-Tu Ralstonia solanacearum, on the other hand. These strong primary structure similarities between EF-Tu from different origins are consistent with the fact that this factor is essential for the translation process in all kingdoms of life. Comparison of the effects of antibiotics on EF-Tu Frateuria and EF-Tu E. coli revealed that enacyloxin, kirromycin and pulvomycin exert a stronger stimulation of the GDP dissociation rate on EF-Tu Frateuria, while the effects of the antibiotics on the GDP association rate were comparable for the two EF-Tu species. Different mutants of EF-Tu E. coli were constructed with the help of site directed mutagenesis by changing one or several residues of EF-Tu E. coli by the corresponding residues of EF-Tu Frateuria. The single A45K substitution did

  2. EF-Tu from the enacyloxin producing Frateuria W-315 strain: Structure/activity relationship and antibiotic resistance.

    Science.gov (United States)

    Créchet, Jean-Bernard; Malosse, Christian; Hountondji, Codjo

    2016-08-01

    In this report, we have demonstrated that the poly(U)-dependent poly(Phe) synthesis activity of elongator factor Tu (EF-Tu) from the enacyloxin producing strain Frateuria sp. W-315 is inhibited by the antibiotic similarly to that of Escherichia coli EF-Tu. The inhibitory effect of enacyloxin observed in a purified system was the same as that obtained with an S30 extract from E. coli or Frateuria sp. W-315, respectively, suggesting that antibiotic resistance of enacyloxin producing Frateuria sp. W-315 is not due neither to EF-Tu nor to other components of the translation machinery but to a still unknown mechanism. The EF-Tu gene, as PCR amplified from Frateuria W-315 genomic DNA and sequenced represented an ORF of 1191 nucleotides corresponding to 396 amino acids. This protein is larger than the product of tufA from E. coli by only two amino acid residues. Alignment of the amino acid sequence of EF-Tu from E. coli with those of Frateuria and Ralstonia solanacearum indicates on average 80% identical amino acid residues and 9.7% conservative replacements between EF-Tu Frateuria and EF-Tu E. coli, on one hand, and 97% identity and 1.7% conservative replacement between EF-Tu Frateuria and EF-Tu Ralstonia solanacearum, on the other hand. These strong primary structure similarities between EF-Tu from different origins are consistent with the fact that this factor is essential for the translation process in all kingdoms of life. Comparison of the effects of antibiotics on EF-Tu Frateuria and EF-Tu E. coli revealed that enacyloxin, kirromycin and pulvomycin exert a stronger stimulation of the GDP dissociation rate on EF-Tu Frateuria, while the effects of the antibiotics on the GDP association rate were comparable for the two EF-Tu species. Different mutants of EF-Tu E. coli were constructed with the help of site directed mutagenesis by changing one or several residues of EF-Tu E. coli by the corresponding residues of EF-Tu Frateuria. The single A45K substitution did

  3. [Analysis of antibiotic usage].

    Science.gov (United States)

    Balpataki, R; Balogh, J; Zelkó, R; Vincze, Z

    2001-01-01

    Economic analysis is founded on the assumption that resources are limited and that should be used in a way that maximizes the benefits gained. Pharmacoeconomics extends these assumptions to drug treatment. Therefore, a full pharmacoeconomic analysis must consider two or more alternative treatments and should be founded on measurement of incremental cost, incremental efficacy, and the value of successful outcome. Antibiotic policy based only on administrative restrictions is failed, instead of it disease formularies and infectologist consultation system are needed. Equally important are various programmes that encourage the cost-conscious use of the antibiotics chosen. Some of the methods evaluated in the literature include: streamlining from combination therapy to a single agent, early switching from parenteral to oral therapy, initiating treatment with oral agents, administering parenteral antibiotic at home from outset of therapy, and antibiotic streamlining programmes that are partnered with infectious disease physicians. The solution is the rational and adequate use of antibiotics, based on the modern theory and practice of antibiotic policy and infection control, that cannot be carried out without the activities of experts in this field. PMID:11769090

  4. Structure-activity relationships in aminosterol antibiotics: the effect of stereochemistry at the 7-OH group.

    Science.gov (United States)

    Tessema, Tsemre-Dingel; Gassler, Frank; Shu, Youheng; Jones, Stephen; Selinsky, Barry S

    2013-06-01

    Squalamine and three aminosterol analogs have been shown to inhibit bacterial cell growth and induce lysis of large unilamellar phospholipid vesicles. The analogs differ in the identity of the polyamine attached at C3 of the sterol, and the stereochemistry of a hydroxyl substituent at C7. Analogs with a tetraammonium spermine polyamine are somewhat more active than analogs with a shorter trisammonium spermidine polyamine, and analogs with an axial (α) hydroxyl substituent at C7 are more active than analogs with the corresponding equatorial (β) hydroxyl group. There is some variability noted; the 7β-OH spermine analog is the most active compound against Escherichia coli, but the least effective against Pseudomonas aeruginosa. Lytic activity correlates well with antimicrobial activity of the compounds, but the lytic activity varies with the phospholipid composition of the vesicles. PMID:23618624

  5. Ozonation of Cephalexin Antibiotic Using Granular Activated Carbon in a Circulating Reactor

    International Nuclear Information System (INIS)

    A circulating reactor was used to decompose cephalexin during catalytic ozonation. The effect of ozone supply and granular activated carbon (GAC) catalyst was investigated for removal of CEX and COD. The regeneration of exhausted activated carbon was investigated during in-situ ozonation. According to results, ozone supply appeared as the most influencing variable followed by dosage of granular activated carbon. The BET surface area, thermogravimetric analysis (TGA) and temperature programmed desorption (TPD) curves indicated that solid phase regeneration of activated carbon using ozone gas followed by mild thermal decomposition was very effective. The adsorption capacity of regenerated activated carbon was slightly lower than virgin activated carbon. The overall study revealed that catalytic ozonation was effective in removing cephalexin from solution and the method can be applied for in-situ ozonation processes. (author)

  6. Specific binding of nisin to the peptidoglycan precursor lipid II combines pore formation and inhibition of cell wall biosynthesis for potent antibiotic activity

    NARCIS (Netherlands)

    Wiedemann, [No Value; Breukink, E; van Kraaij, C; Kuipers, OP; Bierbaum, G; de Kruijff, B; Sahl, HA

    2001-01-01

    Unlike numerous pore-forming amphiphilic peptide antibiotics, the lantibiotic nisin is active in nanomolar concentrations, which results from its ability to use the Lipid-bound cell wall precursor lipid II as a docking molecule for subsequent pore formation. Here we use genetically engineered nisin

  7. Postantibiotic effect assessments for antibiotics exhibiting a wide range of bactericidal activities by using a modified total-cell-counting method.

    OpenAIRE

    Li, R. C.; S.W. Lee

    1997-01-01

    We recently described a total-cell-counting method for postantibiotic effect (PAE) assessments that performs well with weakly bactericidal antibiotics. This note presents a modified method for the study of PAE with extended capability to cover a broad range of bactericidal activities.

  8. Transcriptional regulation of the redD transcriptional activator gene accounts for growth-phase-dependent production of the antibiotic undecylprodigiosin in Streptomyces coelicolor A3(2)

    NARCIS (Netherlands)

    Takano, E.; Gramajo, H.C.; Strauch, E.; White, J.; Bibb, M.J.

    1992-01-01

    Transcription of redD, the activator gene required for production of the red-pigmented antibiotic undecylprodigiosin by Streptomyces coelicolor A3(2), showed a dramatic increase during the transition from exponential to stationary phase. The increase in redD expression was followed by transcription

  9. Evaluation of Antibacterial Activity of Aqueous Extracts of Onion and some Antibiotics on a Number of Important Bacteria in Terms of Food Hygiene

    Directory of Open Access Journals (Sweden)

    Anzabi Younes

    2014-10-01

    Full Text Available Objective: The purpose of this study was to evaluate the antibacterial effect of edible onion plant and a number of common antibiotics in the case of some important bacteria regarding food hygiene. Materials and Methods: The sensitivity or resistance of standard strains of 9 important species of transmissible pathogenic bacteria, through food in laboratory Mueller Hinton agar medium and using blank paper discs containing onion extract, 9 standard synthetic chemicals, and antibiotics by agar disk diffusion method (disk diffusion agar, were investigated. Results: The findings of this study showed that, of the 9 species of bacteria tested, the aqueous extract of onion only has relatively small antibacterial activity on the 2 species of Staphylococcus aureus and clostridium perfringens. Statistical analysis of the results also indicated that there was no significant relationship among the different antibiotics used and the edible onion aqueous extract, and the resistance or susceptibility of isolates. Moreover, there was a difference between different antibiotics tested in this study and aqueous extract of onion, regarding the number of resistant bacteria, and intermediate and moderate susceptibility, and susceptibility to the antibacterial compounds. Conclusion: It seems that the aqueous extract of onions cannot be used as an alternative to commonly used antibiotics to fight important bacteria in terms food hygiene.

  10. Investigations into the in vitro antimicrobial activity and mode of action of the phenazine antibiotic D-alanylgriseoluteic acid.

    Science.gov (United States)

    Giddens, Stephen R; Bean, David C

    2007-01-01

    D-Alanylgriseoluteic acid (AGA) is a potent antimicrobial phenazine compound produced by Pantoea agglomerans (Erwinia herbicola) Eh1087. Susceptibility tests against a range of microbes indicated that AGA had a broad spectrum of antimicrobial activity and was particularly active against Gram-positive pathogens. Comparison of the in vitro efficacy of AGA with eight other antibiotics against 119 clinical isolates of Streptococcus pneumoniae demonstrated that all were inhibited by low concentrations of AGA (minimal inhibitory concentration range activity suggest that AGA may warrant further investigation. PMID:17189100

  11. Antibiotic Resistance

    DEFF Research Database (Denmark)

    Munck, Christian

    morbidity and mortality as well as an increase in the cost of treatment. Understanding how bacteria respond to antibiotic exposure gives the foundations for a rational approach to counteract antimicrobial resistance. In the work presented in this thesis, I explore the two fundamental sources...... of antimicrobial resistance: (1) adaptive mutations and (2) horizontal acquisition of resistance genes from antibiotic gene reservoirs. By studying the geno- and phenotypic changes of E. coli in response to single and drug-pair exposures, I uncover the evolutionary trajectories leading to adaptive resistance. I...... to rationally design drug combinations that limit the evolution of antibiotic resistance due to counteracting evolutionary trajectories. My results highlight that an in-depth knowledge about the genetic responses to the individual antimicrobial compounds enables the prediction of responses to drug combinations...

  12. Aerosolized Antibiotics.

    Science.gov (United States)

    Restrepo, Marcos I; Keyt, Holly; Reyes, Luis F

    2015-06-01

    Administration of medications via aerosolization is potentially an ideal strategy to treat airway diseases. This delivery method ensures high concentrations of the medication in the targeted tissues, the airways, with generally lower systemic absorption and systemic adverse effects. Aerosolized antibiotics have been tested as treatment for bacterial infections in patients with cystic fibrosis (CF), non-CF bronchiectasis (NCFB), and ventilator-associated pneumonia (VAP). The most successful application of this to date is treatment of infections in patients with CF. It has been hypothesized that similar success would be seen in NCFB and in difficult-to-treat hospital-acquired infections such as VAP. This review summarizes the available evidence supporting the use of aerosolized antibiotics and addresses the specific considerations that clinicians should recognize when prescribing an aerosolized antibiotic for patients with CF, NCFB, and VAP.

  13. Medical-grade honey enriched with antimicrobial peptides has enhanced activity against antibiotic-resistant pathogens

    NARCIS (Netherlands)

    Kwakman, P.H.S.; Boer, den L.; Ruyter-Spira, C.; Creemers-Molenaar, T.; Helsper, J.P.F.G.; Vandenbroucke-Grauls, C.M.J.E.; Zaat, S.A.J.; Velde, te A.A.

    2011-01-01

    Honey has potent activity against both antibioticsensitive and -resistant bacteria, and is an interesting agent for topical antimicrobial application to wounds. As honey is diluted by wound exudate, rapid bactericidal activity up to high dilution is a prerequisite for its successful application. We

  14. THE STUDY OF ANTIBIOTIC- AND FAGOSENSITIVITY OF NOSOCOMIAL STRAINS BACTERIA ISOLATED FROM TRANSPLANTED PATIENTS

    Directory of Open Access Journals (Sweden)

    N. I. Gabrielan

    2011-01-01

    Full Text Available Antibiotic and fagosensitivity most etiologically important nosocomial strains of bacteria – Pseudomonas aeru- ginosa, Klebsiella pneumoniae, E. coli, Proteus spp., Staphylococcus spp. were studied. Multiple drug-resistant bacteria as gram-positive and gram-negative, isolated from 8 substrates, had been demonstrated. With regard to the sensitivity of Pseudomonas aeruginosa >40% was observed in 40–50% of the strains to aminoglycosides – aztreonam, amikacin, netilmicin, and only 23–25% of the strains – to gentamicin and levofloxacin (an average of antibiotic susceptibility was 27%. All strains of ESBL Klebsiella drew up and were sensitive only to imipenem, meropenem and aminoglycosides. Specific phages lysed 43–48% of the strains Pseudomonas aeruginosa and Klebsiella pneumoniae, E. coli, Pro- teus spp., multidrug resistant strains of Staphylococcus spp. It is proposed to introduce the use of phages in clinical practice. 

  15. Involvement of aph(3′)-IIa in the formation of mosaic aminoglycoside resistance genes in natural environments

    Science.gov (United States)

    Woegerbauer, Markus; Kuffner, Melanie; Domingues, Sara; Nielsen, Kaare M.

    2015-01-01

    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 three 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. PMID:26042098

  16. 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.

  17. 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.

  18. Cp*Rh-based indicator-displacement assays for the identification of amino sugars and aminoglycosides.

    Science.gov (United States)

    Zaubitzer, Friederike; Buryak, Andrey; Severin, Kay

    2006-05-01

    Indicator-displacement assays based on the organometallic complex [{Cp*RhCl2}2] (Cp*=pentamethylcyclopentadienyl) and the dye gallocyanine were used to sense amino sugars and aminoglycosides in buffered aqueous solution by conducting UV-visible spectroscopy. The data of three assays at pH 7.0, 8.0, and 9.0 were sufficient to distinguish between the amino sugars galactosamine, glucosamine, mannosamine and the aminoglycosides kanamycin A, kanamycin B, amikacin, apramycin, paromomycin, and streptomycin. Furthermore, the assays were used to characterize mixtures of aminoglycosides and obtain quantitative information about the respective analytes. PMID:16521137

  19. Whole genome sequencing of diverse Shiga toxin-producing and non-producing Escherichia coli strains reveals a variety of virulence and novel antibiotic resistance plasmids

    Science.gov (United States)

    The genomes of a diverse set of Shiga toxin-producing E. coli strains and the presence of 38 plasmids among all the isolates were determined. Among the novel plasmids found, there were eight that encoded resistance genes to antibiotics, including aminoglycosides, carbapenems, penicillins, cephalosp...

  20. Enhanced simultaneous PEC eradication of bacteria and antibiotics by facilely fabricated high-activity {001} facets TiO2 mounted onto TiO2 nanotubular photoanode.

    Science.gov (United States)

    Li, Guiying; Nie, Xin; Chen, Jiangyao; Wong, Po Keung; An, Taicheng; Yamashita, Hiromi; Zhao, Huijun

    2016-09-15

    Biohazards and coexisted antibiotics are two groups of emerging contaminants presented in various aquatic environments. They can pose serious threat to the ecosystem and human health. As a result, inactivation of biohazards, degradation of antibiotics, and simultaneous removal of them are highly desired. In this work, a novel photoanode with a hierarchical structured {001} facets exposed nano-size single crystals (NSC) TiO2 top layer and a perpendicularly aligned TiO2 nanotube array (NTA) bottom layer (NSC/NTA) was successfully fabricated. The morphology and facets of anatase TiO2 nanoparticles covered on the top of NTA layer could be controlled by adjusting precalcination temperature and heating rate as the pure NTA was clamped with glasses. Appropriate recalcination can timely remove surface F from {001} facets, and the photocatalytic activity of the resultant photoanode was subsequently activated. NSC/NTA photoanode fabricated under 500 °C precalcination with 20 °C min(-1) followed by 550 °C recalcination possessed highest photoelectrocatalytic efficiency to simultaneously remove bacteria and antibiotics. Results suggest that two-step calcination is necessary for fabrication of high photocatalytic activity NSC/NTA photoanode. The capability of simultaneous eradication of bacteria and antibiotics shows great potential for development of a versatile approach to effectively purify various wastewaters contaminated with complex pollutants. PMID:27314556

  1. Antifilarial and Antibiotic Activities of Methanolic Extracts of Melaleuca cajuputi Flowers.

    Science.gov (United States)

    Al-Abd, Nazeh M; Nor, Zurainee Mohamed; Mansor, Marzida; Hasan, M S; Kassim, Mustafa

    2016-06-01

    We evaluated the activity of methanolic extracts of Melaleuca cajuputi flowers against the filarial worm Brugia pahangi and its bacterial endosymbiont Wolbachia. Anti-Wolbachia activity was measured in worms and in Aedes albopictus Aa23 cells by PCR, electron microscopy, and other biological assays. In particular, microfilarial release, worm motility, and viability were determined. M. cajuputi flower extracts were found to significantly reduce Wolbachia endosymbionts in Aa23 cells, Wolbachia surface protein, and microfilarial release, as well as the viability and motility of adult worms. Anti-Wolbachia activity was further confirmed by observation of degraded and phagocytized Wolbachia in worms treated with the flower extracts. The data provided in vitro and in vivo evidence that M. cajuputi flower extracts inhibit Wolbachia, an activity that may be exploited as an alternative strategy to treat human lymphatic filariasis. PMID:27417081

  2. Synthesis and Antibacterial Activity of Some Heterocyclic Chalcone Analogues Alone and in Combination with Antibiotics

    Directory of Open Access Journals (Sweden)

    Tuong-Ha Do

    2012-06-01

    Full Text Available A series of simple heterocyclic chalcone analogues have been synthesized by Claisen Schmidt condensation reactions between substituted benzaldehydes and heteroaryl methyl ketones and evaluated for their antibacterial activity. The structures of the synthesized chalcones were established by IR and 1H-NMR analysis. The biological data shows that compounds p5, f6 and t5 had strong activities against both susceptible and resistant Staphylococcus aureus strains, but not activity against a vancomycin and methicillin resistant Staphylococcus aureus isolated from a human sample. The structure and activity relationships confirmed that compounds f5, f6 and t5 are potential candidates for future drug discovery and development.

  3. Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

    OpenAIRE

    Chandrasekaran, R.; Ashok Kumar, G. V.

    2011-01-01

    Solvent extracts of native purple non-sulfur bacterial (PNSB) isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India) were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the...

  4. [Quorum sensing systems of regulation, synthesis of phenazine antibiotics, and antifungal (corrected) activity in rhizospheric bacterium Pseudomonas chlororaphis 449].

    Science.gov (United States)

    Veselova, M a; Klein, Sh; Bass, I A; Lipasova, V A; Metlitskaia, A Z; Ovadis, M I; Chernin, L S; Khmel', I A

    2008-12-01

    Strain Pseudomonas chlororaphis 449, an antagonist of a broad spectrum of phytopathogenic microorganisms isolated from the maize rhizosphere, was shown to produce three phenazine antibiotics: phenazine-1-carboxylic acid (PCA), 2-hydroxylphenazine-1-carboxylic acid (2-OH-PCA), and 2-hydroxylphenazine (2-OH-PHZ). Two Quorum Sensing (QS) systems of regulation were identified: PhzIR and CsaI/R. Genes phzI and csaI were cloned and sequenced. Cells of strain 449 synthesize at least three types of AHL: N-butanoyl-L-homoserine lactone (C4-AHL), N-hexanoyl-L-homoserine lactone (C6-AHL), and N-(3-oxo-hexanoyl)-L-homoserine lactone (30C6-AHL). Transposon mutagenesis was used to generate mutants of strain 449 deficient in synthesis of phenazines, which carried inactivated phzA and phzB genes of the phenazine operon and gene phzO. Mutations phzA- and phzB-caused a drastic reduction in the antagonistic activity of bacteria toward phytopathogenic fungi. Both mutants lost the ability to protect cucumber and leguminous plants against phytopathogenic fungi Rhizoctonia solani and Sclerotinia sclerotiorum. These results suggest a significant role of phenazines in the antagonistic activity of P. chlororaphis 449. PMID:19178080

  5. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    Science.gov (United States)

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.

  6. Aminoglycoside ototoxicity in three murine strains and effects on NKCC1 of stria vascularis

    Institute of Scientific and Technical Information of China (English)

    CHU Han-qi; XIONG Hao; Zhou Xiao-qin; HAN Fang; WU Zhen-gong; ZHANG Ping; HUANG Xiao-wen; CUI Yong-hua

    2006-01-01

    Background After establishing a murine model of aminoglycoside antibiotic (AmAn) induced ototoxicity, the sensitivity of AmAn induced ototoxicity in three murine strains and the effect of kanamycin on the expression of Na-K-2C1 cotransporter-1 (NKCC 1) in stria vascularis were investigated.Methods C57BL/6J, CBA/CaJ, NKCC1+/- mice (24 of each strain) were randomly divided into four experimental groups: A: kanamycin alone; B: kanamycin plus 2,3-dihydroxybenzoate; C: 2,3-dihydroxybenzoate alone; and D: control group. Mice were injected with kanamycin or/and 2,3-dihydroxybenzoate twice daily for 14 days. Auditory brainstem response (ABR) was measured and morphology of cochlea delineated with succinate dehydrogenase staining. Expression of NKCC1 in stria vascularis was detected immunohistochemically.Results All three strains in groups A and B developed significant ABR threshold shifts (P<0.01), which were accompanied by outer hair cell loss. NKCC 1 expression in stria vascularis was the weakest in group A (A cf D,P<0.01) and the strongest in groups C and D (P<0.05). CBA/CaJ mice had the highest sensitivity to AmAn.Conclusions Administration of kanamycin established AmAn induced ototoxicity. Kanamycin inhibited the expression of NKCC1 in stria vascularis. 2, 3-dihydroxybenzoate attenuated AmAn induced ototoxicitypossibly by enhancing the expression of NKCC1. Age related hearing loss did not show additional sensitivity to AmAn induced ototoxicity in murine model.

  7. Characterization of a C3 Deoxygenation Pathway Reveals a Key Branch Point in Aminoglycoside Biosynthesis.

    Science.gov (United States)

    Lv, Meinan; Ji, Xinjian; Zhao, Junfeng; Li, Yongzhen; Zhang, Chen; Su, Li; Ding, Wei; Deng, Zixin; Yu, Yi; Zhang, Qi

    2016-05-25

    Apramycin is a clinically interesting aminoglycoside antibiotic (AGA) containing a highly unique bicyclic octose moiety, and this octose is deoxygenated at the C3 position. Although the biosynthetic pathways for most 2-deoxystreptamine-containing AGAs have been well characterized, the pathway for apramycin biosynthesis, including the C3 deoxygenation process, has long remained unknown. Here we report detailed investigation of apramycin biosynthesis by a series of genetic, biochemical and bioinformatical studies. We show that AprD4 is a novel radical S-adenosyl-l-methionine (SAM) enzyme, which uses a noncanonical CX3CX3C motif for binding of a [4Fe-4S] cluster and catalyzes the dehydration of paromamine, a pseudodisaccharide intermediate in apramycin biosynthesis. We also show that AprD3 is an NADPH-dependent reductase that catalyzes the reduction of the dehydrated product from AprD4-catalyzed reaction to generate lividamine, a C3' deoxygenated product of paromamine. AprD4 and AprD3 do not form a tight catalytic complex, as shown by protein complex immunoprecipitation and other assays. The AprD4/AprD3 enzyme system acts on different pseudodisaccharide substrates but does not catalyze the deoxygenation of oxyapramycin, an apramycin analogue containing a C3 hydroxyl group on the octose moiety, suggesting that oxyapramycin and apramycin are partitioned into two parallel pathways at an early biosynthetic stage. Functional dissection of the C6 dehydrogenase AprQ shows the crosstalk between different AGA biosynthetic gene clusters from the apramycin producer Streptomyces tenebrarius, and reveals the remarkable catalytic versatility of AprQ. Our study highlights the intriguing chemistry in apramycin biosynthesis and nature's ingenuity in combinatorial biosynthesis of natural products. PMID:27120352

  8. Characterization of a C3 Deoxygenation Pathway Reveals a Key Branch Point in Aminoglycoside Biosynthesis.

    Science.gov (United States)

    Lv, Meinan; Ji, Xinjian; Zhao, Junfeng; Li, Yongzhen; Zhang, Chen; Su, Li; Ding, Wei; Deng, Zixin; Yu, Yi; Zhang, Qi

    2016-05-25

    Apramycin is a clinically interesting aminoglycoside antibiotic (AGA) containing a highly unique bicyclic octose moiety, and this octose is deoxygenated at the C3 position. Although the biosynthetic pathways for most 2-deoxystreptamine-containing AGAs have been well characterized, the pathway for apramycin biosynthesis, including the C3 deoxygenation process, has long remained unknown. Here we report detailed investigation of apramycin biosynthesis by a series of genetic, biochemical and bioinformatical studies. We show that AprD4 is a novel radical S-adenosyl-l-methionine (SAM) enzyme, which uses a noncanonical CX3CX3C motif for binding of a [4Fe-4S] cluster and catalyzes the dehydration of paromamine, a pseudodisaccharide intermediate in apramycin biosynthesis. We also show that AprD3 is an NADPH-dependent reductase that catalyzes the reduction of the dehydrated product from AprD4-catalyzed reaction to generate lividamine, a C3' deoxygenated product of paromamine. AprD4 and AprD3 do not form a tight catalytic complex, as shown by protein complex immunoprecipitation and other assays. The AprD4/AprD3 enzyme system acts on different pseudodisaccharide substrates but does not catalyze the deoxygenation of oxyapramycin, an apramycin analogue containing a C3 hydroxyl group on the octose moiety, suggesting that oxyapramycin and apramycin are partitioned into two parallel pathways at an early biosynthetic stage. Functional dissection of the C6 dehydrogenase AprQ shows the crosstalk between different AGA biosynthetic gene clusters from the apramycin producer Streptomyces tenebrarius, and reveals the remarkable catalytic versatility of AprQ. Our study highlights the intriguing chemistry in apramycin biosynthesis and nature's ingenuity in combinatorial biosynthesis of natural products.

  9. The Antibiotic Resistance Problem Revisited

    Science.gov (United States)

    Lawson, Michael A.

    2008-01-01

    The term "antibiotic" was first proposed by Vuillemin in 1889 but was first used in the current sense by Walksman in 1941. An antibiotic is defined as a "derivative produced by the metabolism of microorganisms that possess antibacterial activity at low concentrations and is not toxic to the host." In this article, the author describes how…

  10. Influence of First-Line Antibiotics on the Antibacterial Activities of Acetone Stem Bark Extract of Acacia mearnsii De Wild. against Drug-Resistant Bacterial Isolates

    Directory of Open Access Journals (Sweden)

    Olufunmiso O. Olajuyigbe

    2014-01-01

    Full Text Available Background. This study was aimed at evaluating the antibacterial activity of the acetone extract of A. mearnsii and its interactions with antibiotics against some resistant bacterial strains. Methods. The antibacterial susceptibility testing was determined by agar diffusion and macrobroth dilution methods while the checkerboard method was used for the determination of synergy between the antibiotics and the extract. Results. The results showed that the susceptibility of the different bacterial isolates was concentration dependent for the extract and the different antibiotics. With the exception of S. marcescens, the inhibition zones of the extract produced by 20 mg/mL ranged between 18 and 32 mm. While metronidazole did not inhibit any of the bacterial isolates, all the antibiotics and their combinations, except for ciprofloxacin and its combination, did not inhibit Enterococcus faecalis. The antibacterial combinations were more of being antagonistic than of being synergistic in the agar diffusion assay. From the macrobroth dilution, the extract and the antibiotics exerted a varied degree of inhibitory effect on the test organisms. The MIC values of the acetone extract which are in mg/mL are lower than those of the different antibiotics which are in μg/mL. From the checkerboard assay, the antibacterial combinations showed varied degrees of interactions including synergism, additive, indifference, and antagonism interactions. While antagonistic and additive interactions were 14.44%, indifference interaction was 22.22% and synergistic interaction was 37.78% of the antibacterial combinations against the test isolates. While the additivity/indifference interactions indicated no interactions, the antagonistic interaction may be considered as a negative interaction that could result in toxicity and suboptimal bioactivity. Conclusion. The synergistic effects of the herbal-drug combinations may be harnessed for the discovery and development of more

  11. Enhancement of Antibacterial Activity of Capped Silver Nanoparticles in Combination with Antibiotics, on Model Gram-Negative and Gram-Positive Bacteria

    Directory of Open Access Journals (Sweden)

    Aruna Jyothi Kora

    2013-01-01

    Full Text Available The nanoparticles used in this study were prepared from AgNO3 using NaBH4 in the presence of capping agents such as citrate, sodium dodecyl sulfate, and polyvinylpyrrolidone. The formed nanoparticles were characterized with UV-Vis, TEM, and XRD. The generation of silver nanoparticles was confirmed from the appearance of yellow colour and an absorption maximum between 399 and 404 nm. The produced nanoparticles were found to be spherical in shape and polydisperse. For citrate, SDS, and PVP capped nanoparticles, the average particle sizes were 38.3±13.5, 19.3±6.0, and 16.0±4.8 nm, respectively. The crystallinity of the nanoparticles in FCC structure is confirmed from the SAED and XRD patterns. Also, the combined antibacterial activity of these differently capped nanoparticles with selected antibiotics (streptomycin, ampicillin, and tetracycline was evaluated on model Gram-negative and Gram-positive bacteria, employing disc diffusion assay. The activity of the tested antibiotics was enhanced in combination with all the stabilized nanoparticles, against both the Gram classes of bacteria. The combined effects of silver nanoparticles and antibiotics were more prominent with PVP capped nanoparticles as compared to citrate and SDS capped ones. The results of this study demonstrate potential therapeutic applications of silver nanoparticles in combination with antibiotics.

  12. PCR-based site-specific mutagenesis of peptide antibiotics FALL-39 and its biologic activities

    Institute of Scientific and Technical Information of China (English)

    Yun-xia YANG; Yun FENG; Bo-yao WANG; Qi WU

    2004-01-01

    AIM: To construct PGEX-1λT-FALL-39 expression vector and its mutant vector, and study the relationship of function and structure. METHODS: A cDNA encoding mature FALL-39 was cloned from SPCA- 1 cell mRNA and the prokaryotic expression vector PGEX- 1λT-FALL-39 was constructed. Two kinds of polymerase chain reaction (PCR) for the site-direction mutagenesis were used to construct FALL-39 mutant expression vector, FALL-39-Lys-32 and FALL-39-Lys-24. Minimal effective concentration, minimal inhibitory concentration, and minimal bactericidal concentration were used to assay the antibacterial activities of these peptides. Effects of different solution on the antibacterial activity of FALL-39 and FALL-39-Lys-32 were observed by CFU determination. The hemolytic effects of these peptides were also examined on human red blood cells. RESULTS: Two site-specific mutants FALL-39-Lys-32 and FALL-39-Lys24 were obtained by PCR-induced mutagenesis. In comparison with two-step PCR which required two pairs of primers, one step PCR which required one pair of primers is a simple and efficient method for the PCR based site-specific mutagenesis. Using the prokaryotic expression system, the E coli-based products of recombinant FALL39 and its mutant peptides were also obtained. The antibacterial assay showed that FALL-39-Lys-32 and FALL-39-Lys24 were more potential in the antibacterial activity against E coli ML35p and Pseltdomonas aeruginosa ATCC27853 than that of FALL-39, and no increase in hemolysis was observed at the antibacterial concentrations. The antibacterial activity of FALL-39-Lys-32 against E coli was more potent than that of FALL-39 in NaCl-containing LB medium, while its activity was almost the same as FALL-39 in SO2-4 containing Medium E. CONCLUSION: PCR-based mutagensis is a useful model system for studying the structure and function relationship of antimicrobial peptides. Keeping α-helical conformation of FALL-39 and increasing net positive charge can increase the

  13. Practices and Factors Influencing the Use of Antibiotics in Selected Poultry Farms in Ghana

    DEFF Research Database (Denmark)

    Boamah, VE; Odoi, H; Dalsgaard, Anders

    2016-01-01

    and to assess factors influencing farmers’ choice of antibiotics for use on their farms. A cross-sectional survey using questionnaires and semistructured interviews was conducted among 400 poultry farms in the Ashanti, Brong-Ahafo and Greater Accra regions of Ghana. Data was analysed using IBM SPSS...... and Microsoft Excel. Multivariate analyses were used to evaluate correlations between farm variables and the dependency of antibiotic use on internal and external farm characteristics. Farmers reported the use of 35 different antimicrobial agents for management of conditions such as Newcastle, fowl pox......, coccidiosis, and coryza. From these agents, 20 essential antibiotics belonging to 10 antibiotic classes were extracted. Frequently employed antibiotics were tetracyclines (24.17%), aminoglycosides (17.87%), penicillins (16.51%) and fluoroquinolones (10.55%). Only 63% of the farms completed recommended...

  14. Properties and limits of some essential oils: chemical characterisation, antimicrobial activity, interaction with antibiotics and cytotoxicity.

    Science.gov (United States)

    Scazzocchio, Francesca; Garzoli, Stefania; Conti, Cinzia; Leone, Claudia; Renaioli, Clio; Pepi, Federico; Angiolella, Letizia

    2016-09-01

    Because of the emergence of multi-drug resistance bacteria and fungi, alternatives to conventional antimicrobial therapy are needed. This study aims to evaluate in vitro the antimicrobial activity of: Mirtus communis, Coriandrum sativum, Pelargonium capitatum, Cuminum cyminum, Ocimum basilicum, Citrus aurantium amara, Cymbopogon. winterianus, Cymbopogon martini, Salvia sclarea, Melaleuca alternifolia and Mentha suaveolens essential oils on bacteria and fungi, in relation to their chemical composition. The potential interaction of M. alternifolia (TTO), C. sativum (CDO) and M. suaveolens (EOMS) essential oils when used in combination with gentamicin and fluconazole has been evaluated. The results obtained showed a synergic effect on some bacteria and fungi, with FICI values ≤5. The cytotoxicity of TTO, CDO and EOMS was investigated towards HeLa cells. Only EOMS did not result cytotoxic at the active concentrations on micro-organisms. Further studies are necessary to obtain optimal ratios and dosing regimens for higher therapeutic efficacy and to decrease toxicological profiles. PMID:26395247

  15. A convergent ring-closing metathesis approach to carbohydrate-based macrolides with potential antibiotic activity.

    Science.gov (United States)

    Blom, Petra; Ruttens, Bart; Van Hoof, Steven; Hubrecht, Idzi; Van der Eycken, Johan; Sas, Benedikt; Van hemel, Johan; Vandenkerckhove, Jan

    2005-11-25

    [reaction: see text] An efficient convergent approach has been developed for the construction of novel, non-natural, carbohydrate-based macrolides. The key step in the synthesis is the formation of the macrocyclic ring via a ring-closing metathesis reaction. The obtained macrolide analogues have been screened for biological activity against gram-positive and gram-negative bacteria, including resistant strains, yeasts, and molds.

  16. Synthesis and Antibacterial Activity of Some Heterocyclic Chalcone Analogues Alone and in Combination with Antibiotics

    OpenAIRE

    Tuong-Ha Do; Thi-Ngoc-Phuong Huynh; Khac-Minh Thai; Cat-Dong Tran; Thanh-Dao Tran; Thi-Thao-Nhu Nguyen

    2012-01-01

    A series of simple heterocyclic chalcone analogues have been synthesized by Claisen Schmidt condensation reactions between substituted benzaldehydes and heteroaryl methyl ketones and evaluated for their antibacterial activity. The structures of the synthesized chalcones were established by IR and 1H-NMR analysis. The biological data shows that compounds p5, f6 and <...

  17. The aac(6'Ib gene in Proteus mirabilis strains resistant to aminoglycosides.

    Directory of Open Access Journals (Sweden)

    Jerzy Ratajczak

    2009-01-01

    Full Text Available The aim of this study was to evaluate the presence of aac(6'-Ib gene conferring resistance to aminoglycosides in Proteus mirabilis strains. Five isolates had aac(6'-Ib gene. In one case the gene was no-expressed. Three isolates were resistant to all aminoglycosides and minimum inhibitory concentrations were > or = 256 microg/ml. Additionally, all positive strains were resistant to tetracycline and ciprofloxacin.

  18. In vitro and in vivo anti-malarial activity of tigecycline, a glycylcycline antibiotic, in combination with chloroquine

    OpenAIRE

    Sahu, Rajnish; Walker, Larry A.; Tekwani, Babu L.

    2014-01-01

    Background Several antibiotics have shown promising anti-malarial effects and have been useful for malarial chemotherapy, particularly in combination with standard anti-malarial drugs. Tigecycline, a semi-synthetic derivative of minocycline with a unique and novel mechanism of action, is the first clinically available drug in a new class of glycylcycline antibiotics. Methods Tigecycline was tested in vitro against chloroquine (CQ)-sensitive (D6) and resistant strains (W2) of Plasmodium falcip...

  19. Antibiotics for prophylaxis of Plasmodium falciparum infections : in vitro activity of doxycycline against Senegalese isolates

    OpenAIRE

    Pradines, B; Spiegel, A.; Rogier, C; Tall, A; Mosnier, J.; Fusai, T.; Trape, Jean-François; Parzy, D

    2000-01-01

    The in vitro acivities of doxycycline, chloroquine, quinine, amodiaquine, artemether, pyrimethamine, and cycloguanil were evaluated against #Plasmodium falciparum$ isolates from Senegal (Dielmo and Ndiop), using an isotopic, micro, drug susceptibility test. The 71 50% inhibitory concentration (IC50) values for doxycycline ranged from 0.7 to 108.0 microMol and the geometric mean IC50 for the 71 isolates was 11.3 microMol (95% confidence interval = 9.5-13.4 microM). The activity of doxycycline ...

  20. Optically pure, water-stable metallo-helical ‘flexicate’ assemblies with antibiotic activity

    Science.gov (United States)

    Howson, Suzanne E.; Bolhuis, Albert; Brabec, Viktor; Clarkson, Guy J.; Malina, Jaroslav; Rodger, Alison; Scott, Peter

    2012-01-01

    The helicates—chiral assemblies of two or more metal atoms linked by short or relatively rigid multidentate organic ligands—may be regarded as non-peptide mimetics of α-helices because they are of comparable size and have shown some relevant biological activity. Unfortunately, these beautiful helical compounds have remained difficult to use in the medicinal arena because they contain mixtures of isomers, cannot be optimized for specific purposes, are insoluble, or are too difficult to synthesize. Instead, we have now prepared thermodynamically stable single enantiomers of monometallic units connected by organic linkers. Our highly adaptable self-assembly approach enables the rapid preparation of ranges of water-stable, helicate-like compounds with high stereochemical purity. One such iron(II) ‘flexicate’ system exhibits specific interactions with DNA, promising antimicrobial activity against a Gram-positive bacterium (methicillin-resistant Staphylococcus aureus, MRSA252), but also, unusually, a Gram-negative bacterium (Escherichia coli, MC4100), as well as low toxicity towards a non-mammalian model organism (Caenorhabditis elegans).

  1. Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water

    Directory of Open Access Journals (Sweden)

    Khalifa Sifaw Ghenghesh

    2001-02-01

    Full Text Available The use of untreated water for drinking and other activities have been associated with intestinal and extraintestinal infections in humans due to Aeromonas species. In the present study aeromonads were isolated from 48.7% of 1,000 water samples obtained from wells and other miscellaneous sources. Aeromonas species were detected in 45% of samples tested in spring, 34.5% in summer, 48% in autumn and 60% of samples tested in winter. Speciation of 382 strains resulted in 225 (59% being A. hydrophila, 103 (27% A. caviae, 42 (11% A. sobria and 11 (3% atypical aeromonads. Of 171 Aeromonas strains tested for their haemolytic activity, 53%, 49%, 40% and 37% were positive in this assay using human, horse, sheep and camel erythrocytes respectively. The results obtained indicate that potentially enteropathogenic Aeromonas species are commonly present in untreated drinking water obtained from wells in Libya (this may also apply to other neighbouring countries which may pose a health problem to users of such water supplies. In addition, ceftriaxone and ciprofloxacin are suitable drugs that can be used in the treatment of Aeromonas-associated infections, particularly in the immunocompromised, resulting from contact with untreated sources of water.

  2. Prevalence, species differentiation, haemolytic activity, and antibiotic susceptibility of aeromonads in untreated well water.

    Science.gov (United States)

    Ghenghesh, K S; El-Ghodban, A; Dkakni, R; Abeid, S; Altomi, A; Abdussalam, T; Marialigeti, K

    2001-02-01

    The use of untreated water for drinking and other activities have been associated with intestinal and extraintestinal infections in humans due to Aeromonas species. In the present study aeromonads were isolated from 48.7% of 1,000 water samples obtained from wells and other miscellaneous sources. Aeromonas species were detected in 45% of samples tested in spring, 34.5% in summer, 48% in autumn and 60% of samples tested in winter. Speciation of 382 strains resulted in 225 (59%) being A. hydrophila, 103 (27%) A. caviae, 42 (11%) A. sobria and 11 (3%) atypical aeromonads. Of 171 Aeromonas strains tested for their haemolytic activity, 53%, 49%, 40% and 37% were positive in this assay using human, horse, sheep and camel erythrocytes respectively. The results obtained indicate that potentially enteropathogenic Aeromonas species are commonly present in untreated drinking water obtained from wells in Libya (this may also apply to other neighbouring countries) which may pose a health problem to users of such water supplies. In addition, ceftriaxone and ciprofloxacin are suitable drugs that can be used in the treatment of Aeromonas-associated infections, particularly in the immunocompromised, resulting from contact with untreated sources of water.

  3. RpoS plays a central role in the SOS induction by sub-lethal aminoglycoside concentrations in Vibrio cholerae.

    Directory of Open Access Journals (Sweden)

    Zeynep Baharoglu

    Full Text Available Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC of aminoglycosides (AGs induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC.

  4. Infections in neurologic surgery. The intraventricular use of antibiotics.

    Science.gov (United States)

    Wen, D Y; Bottini, A G; Hall, W A; Haines, S J

    1992-04-01

    Intraventricular antibiotic therapy appears to be a useful treatment modality in those CSF infections in which systemic therapy may fail. Consideration should be given to using this form of treatment when infecting organisms are only sensitive to antibiotics with poor penetration of the CSF (e.g., aminoglycosides and vancomycin) and for cases in which intravenous therapy has failed to sterilize the CSF, toxicity from systemic therapy precludes further increases in dosages, and shunts or other CSF hardware might be expected to reduce the efficacy of systemic therapy by providing a foreign body to harbor organisms. Shunts or reservoirs that are infected may be successfully sterilized with IVT therapy alone or in conjunction with systemic therapy, but this has a lower success rate than cases in which the shunt is removed. There is a wealth of clinical experience with IVT vancomycin and gentamicin that suggests that they are relatively safe. Until more data are available on other aminoglycosides and newer antibiotics, these two agents should be considered the antibiotics of choice for IVT therapy. In situations in which the organism is sensitive to both vancomycin and gentamicin, vancomycin should be used in view of the documented neurotoxicity seen with gentamicin. When gentamicin resistance occurs, amikacin and tobramycin are appropriate alternatives. The high risk of epilepsy with the penicillins and cephalosporins makes them less suited for IVT therapy, although the newer cephalosporins have some promise for IVT therapy. CNS fungal infections can be treated effectively with IVT amphotericin B but with a high risk of significant toxicity. Miconazole appears to be safer than amphotericin B but there is less clinical experience with this drug. Table 1 summarizes the dosages, indications, and toxicity of those antibiotics commonly used for intraventricular administration, which have been reported previously.

  5. An antibiotic complex from Lysobacter enzymogenes strain C3: antimicrobial activity and role in plant disease control.

    Science.gov (United States)

    Li, S; Jochum, C C; Yu, F; Zaleta-Rivera, K; Du, L; Harris, S D; Yuen, G Y

    2008-06-01

    Lysobacter enzymogenes C3 is a bacterial biological control agent that exhibits antagonism against multiple fungal pathogens. Its antifungal activity was attributed in part to lytic enzymes. In this study, a heat-stable antifungal factor (HSAF), an antibiotic complex consisting of dihydromaltophilin and structurally related macrocyclic lactams, was found to be responsible for antagonism by C3 against fungi and oomycetes in culture. HSAF in purified form exhibited inhibitory activity against a wide range of fungal and oomycetes species in vitro, inhibiting spore germination, and disrupting hyphal polarity in sensitive fungi. When applied to tall fescue leaves as a partially-purified extract, HSAF at 25 mug/ml and higher inhibited germination of conidia of Bipolaris sorokiniana compared with the control. Although application of HSAF at 12.5 mug/ml did not reduce the incidence of conidial germination, it inhibited appressorium formation and suppressed Bipolaris leaf spot development. Two mutant strains of C3 (K19 and DeltaNRPS) that were disrupted in different domains in the hybrid polyketide synthase-nonribosomal peptide synthetase gene for HSAF biosynthesis and had lost the ability to produce HSAF were compared with the wild-type strain for biological control efficacy against Bipolaris leaf spot on tall fescue and Fusarium head blight, caused by Fusarium graminearum, on wheat. Both mutant strains exhibited decreased capacity to reduce the incidence and severity of Bipolaris leaf spot compared with C3. In contrast, the mutant strains were as efficacious as the wild-type strain in reducing the severity of Fusarium head blight. Thus, HSAF appears to be a mechanism for biological control by strain C3 against some, but not all, plant pathogenic fungi.

  6. Enhancement of the antibiotic activity of erythromycin by volatile compounds of Lippia alba (Mill. N.E. Brown against Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Helenicy N.H. Veras

    2011-01-01

    Full Text Available Background: Lippia alba (Mill. N.E. Brown, popularly known as "erva-cidreira," is commonly found in northeastern Brazil. The leaves tea is used to treat digestive disturbances, nausea, cough, and bronchitis. Objective: This work reports the chemical composition and erythromycin-modifying activity by gaseous contact against Staphylococcus aureus. Materials and Methods: The leaves of L. alba were subjected to hydrodistillation, and the essential oil extracted was examined with respect to the chemical composition, by gas chromatography-mass spectrometry (GC-MS, and the essential oil extracted was evaluated for antibacterial and antibiotic-modifying activity by gaseous contact. Results: The overall yield of essential oil obtained by hydrodistillation was 0.52%. The GC-MS analysis has led to the identification of the main components: geranial (31.4% and neral (29.5%. It was verified that the essential oil interfered with erythromycin antibiotic activity against S. aureus ATCC 25923 was enhanced (221.4% in the presence of 12% essential oil. The 3% essential oil increased the effect against S. aureus ATCC 25923 (41.6% and S. aureus ATCC 6538 (58.3%. Conclusion: The essential oil of L. alba influences the activity of erythromycin and may be used as an adjuvant in antibiotic therapy against respiratory tract bacterial pathogens.

  7. Squalamine: an aminosterol antibiotic from the shark.

    OpenAIRE

    Moore, K.S.; Wehrli, S; Roder, H; Rogers, M.; Forrest, J N; McCrimmon, D; Zasloff, M.

    1993-01-01

    In recent years, a variety of low molecular weight antibiotics have been isolated from diverse animal species. These agents, which include peptides, lipids, and alkaloids, exhibit antibiotic activity against environmental microbes and are thought to play a role in innate immunity. We report here the discovery of a broad-spectrum steroidal antibiotic isolated from tissues of the dogfish shark Squalus acanthias. This water-soluble antibiotic, which we have named squalamine, exhibits potent bact...

  8. Structure of the Antibiotic Resistance Factor Spectinomycin Phosphotransferase from Legionella pneumophila

    Energy Technology Data Exchange (ETDEWEB)

    Fong, D.; Lemke, C; Huang, J; Xiong, B; Berghuis, A

    2010-01-01

    Aminoglycoside phosphotransferases (APHs) constitute a diverse group of enzymes that are often the underlying cause of aminoglycoside resistance in the clinical setting. Several APHs have been extensively characterized, including the elucidation of the three-dimensional structure of two APH(3{prime}) isozymes and an APH(2{double_prime}) enzyme. Although many APHs are plasmid-encoded and are capable of inactivating numerous 2-deoxystreptmaine aminoglycosides with multiple regiospecificity, APH(9)-Ia, isolated from Legionella pneumophila, is an unusual enzyme among the APH family for its chromosomal origin and its specificity for a single non-2-deoxystreptamine aminoglycoside substrate, spectinomycin. We describe here the crystal structures of APH(9)-Ia in its apo form, its binary complex with the nucleotide, AMP, and its ternary complex bound with ADP and spectinomycin. The structures reveal that APH(9)-Ia adopts the bilobal protein kinase-fold, analogous to the APH(3{prime}) and APH(2{double_prime}) enzymes. However, APH(9)-Ia differs significantly from the other two types of APH enzymes in its substrate binding area and that it undergoes a conformation change upon ligand binding. Moreover, kinetic assay experiments indicate that APH(9)-Ia has stringent substrate specificity as it is unable to phosphorylate substrates of choline kinase or methylthioribose kinase despite high structural resemblance. The crystal structures of APH(9)-Ia demonstrate and expand our understanding of the diversity of the APH family, which in turn will facilitate the development of new antibiotics and inhibitors.

  9. Occurrence of Antibiotics and Emerging Contaminants in Dairy Farming

    Science.gov (United States)

    Watanabe, N.; Harter, T.; Bergamaschi, B.

    2007-12-01

    Intense animal husbandry is of growing concern as a potential contamination source of a variety of emerging contaminants including pathogens, naturally occurring and synthetic steroid hormones, and various pharmaceuticals, particularly antibiotics. For example, more than twenty million pounds of antibiotics are sold for use in animal husbandry with 95% going towards therapeutic use. Here, we focus on the application and potential environmental occurrence of pharmaceuticals and disinfectants on dairies. Recommended drug applications are available from national databases. Statistical data on actual usage, however, are not available. We complement national data with interviews and dairy visits for further evaluation of drug and chemical usage (not including pesticides used on crops and fertilizer) and an overall assessment of the potential antibiotics output in dairy waste. We find that aminoglycosides, tetracyclines, and coccidiostats make up much of the total mass of antibiotics used. On dairies using the ionophoric antibiotic monensin as feed additive, monensin makes up a large fraction of the total antibiotics use (by mass). Other chemicals of potential concern include disinfectants used to prevent mastitis, detergents used in the milking parlor, footbath reagents to prevent and treat lameness, and insecticides used to control flies and mites.

  10. Evaluation of the Antimicrobial Activity of the Decoction of Tropidurus hispidus (Spix, 1825 and Tropidurus semitaeniatus (Spix, 1825 Used by the Traditional Medicine

    Directory of Open Access Journals (Sweden)

    Israel J. M. Santos

    2012-01-01

    Full Text Available Tropidurus hispidus and Tropidurus semitaeniatus are two lizard species utilized in traditional medicine in Northeast Brazil. Their medicinal use includes diseases related with bacterial infections such as tonsillitis and pharyngitis. They are used in the form of teas (decoctions for the treatment of illnesses. In this work, we evaluated the antimicrobial activity of the decoctions of T. hispidus (DTH and T. semitaeniatus (DTS against bacterial strains, namely, standard and multiresistant Escherichia coli, Staphylococus aureus, and Pseudomonas aureuginosa, alone and in combination with aminoglycoside antibiotics. The decoctions were prepared using the whole body of the dried lizards, and the filtrate was frozen and lyophilized. When tested alone, the samples did not demonstrate any substantial inhibition of bacterial growth. However, in combination with antibiotics as aminoglycosides, decoctions reduced the minimal inhibitory concentration (MIC of the assayed antibiotics against multiresistant strains of S. aureus and P. aureuginosa. Chemical prospecting tests revealed the presence of alkaloids in DTS. This is the first study evaluating the medicinal efficacy of T. hispidus and T. semitaeniatus and contributes to the list of new sources of medicines from natural products of animal origin.

  11. 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. PMID:26245695

  12. In70 of plasmid pAX22, a bla(VIM-1)-containing integron carrying a new aminoglycoside phosphotransferase gene cassette.

    Science.gov (United States)

    Riccio, M L; Pallecchi, L; Fontana, R; Rossolini, G M

    2001-04-01

    An Achromobacter xylosoxydans strain showing broad-spectrum resistance to beta-lactams (including carbapenems) and aminoglycosides was isolated at the University Hospital of Verona (Verona, Italy). This strain was found to produce metallo-beta-lactamase activity and to harbor a 30-kb nonconjugative plasmid, named pAX22, carrying a bla(VIM-1) determinant inserted into a class 1 integron. Characterization of this integron, named In70, revealed an original array of four gene cassettes containing, respectively, the bla(VIM-1) gene and three different aminoglycoside resistance determinants, including an aacA4 allele, a new aph-like gene named aphA15, and an aadA1 allele. The aphA15 gene is the first example of an aph-like gene carried on a mobile gene cassette, and its product exhibits close similarity to the APH(3')-IIa aminoglycoside phosphotransferase encoded by Tn5 (36% amino acid identity) and to an APH(3')-IIb enzyme from Pseudomonas aeruginosa (38% amino acid identity). Expression of the cloned aphA15 gene in Escherichia coli reduced the susceptibility to kanamycin and neomycin as well as (slightly) to amikacin, netilmicin, and streptomycin. Characterization of the 5' and 3' conserved segments of In70 and of their flanking regions showed that In70 belongs to the group of class 1 integrons associated with defective transposon derivatives originating from Tn402-like elements. The structure of the 3' conserved segment indicates the closest ancestry with members of the In0-In2 lineage. In70, with its array of cassette-borne resistance genes, can mediate broad-spectrum resistance to most beta-lactams and aminoglycosides. PMID:11257042

  13. Macrolones Are a Novel Class of Macrolide Antibiotics Active against Key Resistant Respiratory Pathogens In Vitro and In Vivo.

    Science.gov (United States)

    Čipčić Paljetak, Hana; Verbanac, Donatella; Padovan, Jasna; Dominis-Kramarić, Miroslava; Kelnerić, Željko; Perić, Mihaela; Banjanac, Mihailo; Ergović, Gabrijela; Simon, Nerrisa; Broskey, John; Holmes, David J; Eraković Haber, Vesna

    2016-09-01

    As we face an alarming increase in bacterial resistance to current antibacterial chemotherapeutics, expanding the available therapeutic arsenal in the fight against resistant bacterial pathogens causing respiratory tract infections is of high importance. The antibacterial potency of macrolones, a novel class of macrolide antibiotics, against key respiratory pathogens was evaluated in vitro and in vivo MIC values against Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, and Haemophilus influenzae strains sensitive to macrolide antibiotics and with defined macrolide resistance mechanisms were determined. The propensity of macrolones to induce the expression of inducible erm genes was tested by the triple-disk method and incubation in the presence of subinhibitory concentrations of compounds. In vivo efficacy was assessed in a murine model of S. pneumoniae-induced pneumonia, and pharmacokinetic (PK) profiles in mice were determined. The in vitro antibacterial profiles of macrolones were superior to those of marketed macrolide antibiotics, including the ketolide telithromycin, and the compounds did not induce the expression of inducible erm genes. They acted as typical protein synthesis inhibitors in an Escherichia coli transcription/translation assay. Macrolones were characterized by low to moderate systemic clearance, a large volume of distribution, a long half-life, and low oral bioavailability. They were highly efficacious in a murine model of pneumonia after intraperitoneal application even against an S. pneumoniae strain with constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics. Macrolones are the class of macrolide antibiotics with an outstanding antibacterial profile and reasonable PK parameters resulting in good in vivo efficacy. PMID:27353268

  14. 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

  15. Serum Aminoglycoside Assay by Enzyme-Mediated Immunoassay (EMIT): Correlation with Radioimmunoassay, Fluoroimmunoassay, and Acetyltransferase and Microbiological Assays

    OpenAIRE

    White, L O; Scammell, L. M.; Reeves, D S

    1981-01-01

    Enzyme-mediated immunoassay (EMIT) serum aminoglycoside assay results were accurate and precise and correlated well with radioimmunoassay, fluoroimmunoassay, and acetyltransferase and microbiological assay determinations.

  16. A surprising dipolar cycloaddition provides ready access to aminoglycosides.

    Science.gov (United States)

    Dahl, Russell S; Finney, Nathaniel S

    2004-07-14

    This contribution describes the results of a new research effort in our laboratory aimed at the synthesis of novel aminoglycosides and amino-C-glycosides. Despite the importance of such compounds, and the previous development of some methodological solutions, this remains an important area of research. Notable features of our approach, which is distinct from and complementary to previous efforts, are the following: (1) Reliance on a surprising and unprecedented formation of glycal triazolines via an inverse electron demand dipolar cycloaddition of glucal. We believe this desirable transformation has not previously been discovered because of the unusual selection of substrates and solvent required. (2) Very mild reaction conditions. An initial thermal cycloaddition is carried out in an inert solvent, the triazoline generated is photochemically converted to a reactive aziridine, and the crude aziridine undergoes ring opening at room temperature in the presence of a nucleophile and a mild Lewis acid catalyst. (3) Formation of products lacking an N-acyl group, allowing ready synthesis of novel glucosamine derivatives. PMID:15237974

  17. Antibiotic susceptibility testing of the Gram-negative bacteria based on flow cytometry

    Directory of Open Access Journals (Sweden)

    Claude Saint-Ruf

    2016-07-01

    Full Text Available Rapidly treating infections with adequate antibiotics is of major importance. This requires a fast and accurate determination of the antibiotic susceptibility of bacterial pathogens. The most frequently used methods are slow because they are based on the measurement of growth inhibition. Faster methods, such as PCR-based detection of determinants of antibiotic resistance, do not always provide relevant information on susceptibility, particularly that which is not genetically based. Consequently, new methods, such as the detection of changes in bacterial physiology caused by antibiotics using flow cytometry and fluorescent viability markers, are being explored. In this study, we assessed whether Alexa Fluor® 633 Hydrazide (AFH, which targets carbonyl groups, can be used for antibiotic susceptibility testing. Carbonylation of cellular macromolecules, which increases in antibiotic-treated cells, is a particularly appropriate to assess for this purpose because it is irreversible. We tested the susceptibility of clinical isolates of Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, to antibiotics from the three classes: β-lactams, aminoglycosides and fluoroquinolones. In addition to AFH, we used TO-PRO®-3, which enters cells with damaged membranes and binds to DNA, and DiBAC4 (3, which enters cells with depolarized membranes. We also monitored antibiotic-induced morphological alterations of bacterial cells by analyzing light scattering signals. Although all tested dyes and light scattering signals allowed for the detection of antibiotic-sensitive cells, AFH proved to be the most suitable for the fast and reliable detection of antibiotic susceptibility.

  18. Antibiotic Susceptibility Testing of the Gram-Negative Bacteria Based on Flow Cytometry.

    Science.gov (United States)

    Saint-Ruf, Claude; Crussard, Steve; Franceschi, Christine; Orenga, Sylvain; Ouattara, Jasmine; Ramjeet, Mahendrasingh; Surre, Jérémy; Matic, Ivan

    2016-01-01

    Rapidly treating infections with adequate antibiotics is of major importance. This requires a fast and accurate determination of the antibiotic susceptibility of bacterial pathogens. The most frequently used methods are slow because they are based on the measurement of growth inhibition. Faster methods, such as PCR-based detection of determinants of antibiotic resistance, do not always provide relevant information on susceptibility, particularly that which is not genetically based. Consequently, new methods, such as the detection of changes in bacterial physiology caused by antibiotics using flow cytometry and fluorescent viability markers, are being explored. In this study, we assessed whether Alexa Fluor® 633 Hydrazide (AFH), which targets carbonyl groups, can be used for antibiotic susceptibility testing. Carbonylation of cellular macromolecules, which increases in antibiotic-treated cells, is a particularly appropriate to assess for this purpose because it is irreversible. We tested the susceptibility of clinical isolates of Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, to antibiotics from the three classes: β-lactams, aminoglycosides, and fluoroquinolones. In addition to AFH, we used TO-PRO®-3, which enters cells with damaged membranes and binds to DNA, and DiBAC4 (3), which enters cells with depolarized membranes. We also monitored antibiotic-induced morphological alterations of bacterial cells by analyzing light scattering signals. Although all tested dyes and light scattering signals allowed for the detection of antibiotic-sensitive cells, AFH proved to be the most suitable for the fast and reliable detection of antibiotic susceptibility.

  19. Antibiotic Susceptibility Testing of the Gram-Negative Bacteria Based on Flow Cytometry.

    Science.gov (United States)

    Saint-Ruf, Claude; Crussard, Steve; Franceschi, Christine; Orenga, Sylvain; Ouattara, Jasmine; Ramjeet, Mahendrasingh; Surre, Jérémy; Matic, Ivan

    2016-01-01

    Rapidly treating infections with adequate antibiotics is of major importance. This requires a fast and accurate determination of the antibiotic susceptibility of bacterial pathogens. The most frequently used methods are slow because they are based on the measurement of growth inhibition. Faster methods, such as PCR-based detection of determinants of antibiotic resistance, do not always provide relevant information on susceptibility, particularly that which is not genetically based. Consequently, new methods, such as the detection of changes in bacterial physiology caused by antibiotics using flow cytometry and fluorescent viability markers, are being explored. In this study, we assessed whether Alexa Fluor® 633 Hydrazide (AFH), which targets carbonyl groups, can be used for antibiotic susceptibility testing. Carbonylation of cellular macromolecules, which increases in antibiotic-treated cells, is a particularly appropriate to assess for this purpose because it is irreversible. We tested the susceptibility of clinical isolates of Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, to antibiotics from the three classes: β-lactams, aminoglycosides, and fluoroquinolones. In addition to AFH, we used TO-PRO®-3, which enters cells with damaged membranes and binds to DNA, and DiBAC4 (3), which enters cells with depolarized membranes. We also monitored antibiotic-induced morphological alterations of bacterial cells by analyzing light scattering signals. Although all tested dyes and light scattering signals allowed for the detection of antibiotic-sensitive cells, AFH proved to be the most suitable for the fast and reliable detection of antibiotic susceptibility. PMID:27507962

  20. Beyond Antibiotics?

    Directory of Open Access Journals (Sweden)

    LE Nicolle

    2006-01-01

    Full Text Available The AMMI Canada meeting in March 2006 hosted a symposium exploring the potential alternatives to antibiotics for the prevention and treatment of infection. Four papers summarizing talks from that session are published in this issue of the Journal (1-4. These reviews address the scientific underpinnings for a number of proposed concepts, and summarize the current status of clinical use. The approaches - probiotics, bacteriophage therapy, and manipulation of innate immunity - are all intriguing but are still removed from immediate practical applications.

  1. Mitochondrial DNA A1555G mutation screening using a testing kit method and its significance in preventing aminoglycoside-related hearing loss

    Institute of Scientific and Technical Information of China (English)

    LIU Xin; YANG Weiyan; HAN Dongyi; JIN Zhengce; GUAN Minxin; DAI Pu; HUANG Deliang; YUAN Huijun; LI Weiming; YU Fei; ZHANG Xin; KANG Dongyang; CAO Juyang

    2006-01-01

    To report a new screening method for mitochondrial DNA 1555A→G mutation and the results of genotype analysis in 19 maternal inherited deafness pedigrees. Method Five hundred and forty-six non-syndromic neuro-sensory hearing loss patients were tested for 1555A→G mutation using a new compact testing kit, which allows clear distinction between wild type and 1555 A→G mutated mtDNAs. Results Nineteen subjects among the 546 patients (3.48%) were found to carry mtDNA A1555G mutation. The results were confirmed by sequencing in an ABI 3100 Avant sequencer. Conclusions Maternal inherited deafness families are a frequently seen in outpatient group. The detection ofmtDNA 1555 A→G mutation with a low cost, ready to use detection kit is needed and suitable in China for large scale screening and preventive testing before usage of aminoglycoside antibiotics.

  2. Assessing the antibiotic susceptibility of freshwater cyanobacteria spp.

    Directory of Open Access Journals (Sweden)

    Elsa eDias

    2015-08-01

    Full Text Available Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacteria are ubiquitous in freshwater, where they are exposed to antibiotics and resistant organisms, but their role on water resistome was never evaluated. Data concerning the effects of antibiotics on cyanobacteria, obtained by distinct methodologies, is often contradictory. This emphasizes the importance of developing procedures to understand the trends of antibiotic susceptibility in cyanobacteria. In this study we aimed to evaluate the susceptibility of four cyanobacterial isolates from different genera (Microcystis aeruginosa, Aphanizomenon gracile, Chrisosporum bergii, Planktothix agradhii, and among them nine isolates from the same specie (M. aeruginosa to distinct antibiotics (amoxicillin, ceftazidime, ceftriaxone, kanamycine, gentamicine, tetracycline, trimethoprim, nalidixic acid, norfloxacin. We used a method adapted from the bacteria standard broth microdilution. Cyanobacteria were exposed to serial dilution of each antibiotic (0.0015-1.6 mg/L in Z8 medium (20 ± 1 ºC; 14/10 h L/D cycle; light intensity 16 ± 4 µEm-2 s-1. Cell growth was followed overtime (OD450nm/microscopic examination and the minimum inhibitory concentrations (MICs were calculated for each antibiotic/isolate. We found that -lactams exhibited the lower MICs, aminoglycosides, tetracycline and norfloxacine presented intermediate MICs; none of the isolates were susceptible to trimethoprim and nalidixic acid. The reduced susceptibility of all tested cyanobacteria to some antibiotics suggests that they might be naturally non-susceptible to these compounds, or that that they might became non-susceptible due to antibiotic contamination pressure, or to the transfer of genes from resistant bacteria present in the environment.

  3. Detection of high-level aminoglycoside resistant pattern of Enterococci isolated from urine samples at a tertiary care hospital in Bengaluru

    Directory of Open Access Journals (Sweden)

    Smeeta Huidrom

    2016-01-01

    Full Text Available Aims: Enterococcus species are major nosocomial pathogens and they most commonly cause urinary tract infections (UTIs, exhibiting vancomycin and high-level aminoglycoside resistance (HLAR with increasing frequency, resulting in high mortality of patients with serious enterococcal infections. Detection of resistance is thus of paramount importance. The present study aims to detect and determine the HLAR pattern of Enterococci isolated from urine samples of patients diagnosed with UTI at our hospital. Materials and Methods: This study was carried out at a tertiary care hospital in Bengaluru for a period of 1 year from January 2013 to December 2013. A total of 105 enterococcal strains were isolated from urine samples and speciated as per the scheme of Facklam and Collins. Antibiotic susceptibility was determined for various drugs by Kirby–Bauer disc diffusion method. The results were interpreted as per the Clinical and Laboratory Standards Institute (CLSI guidelines. Results: Ninety-three of the 105 (88.6% isolates showed high-level resistance to gentamicin and/or streptomycin. Combined resistance to both the aminoglycosides, high level gentamicin and streptomycin (HLAR, was seen only in Enterococcus faecalis 20/105 (19.04%. Of the two isolates of Enterococcus faecium, 1 (50% was seen to be resistant to high level gentamicin. The HLAR E. faecalis and E. faecium isolates also showed concordant resistance to multiple antibiotics including vancomycin. Conclusion: This study highlights the need to screen for HLAR in patients suffering from enterococcal infections. Routine screening for HLAR is important to limit the spread of resistance and to have a surveillance program.

  4. Impact of galacto-oligosaccharides on the gut microbiota composition and metabolic activity upon antibiotic treatment during in vitro fermentation

    NARCIS (Netherlands)

    Ladirat, S.E.; Schuren, F.H.J.; Schoterman, M.H.C.; Nauta, A.; Gruppen, H.; Schols, H.A.

    2014-01-01

    Prebiotics are considered to have potential to reduce disturbances in the gut microbiota induced by antibiotics. Results in literature are, however, not consistent. The current in vitro study conducted in a fermentation screening platform allowed to unambiguously compare the impact of galacto-oligos

  5. Antimicrobial Peptide from the Wild Bee Hylaeus signatus Venom and Its Analogues: Structure-Activity Study and Synergistic Effect with Antibiotics.

    Science.gov (United States)

    Nešuta, Ondřej; Hexnerová, Rozálie; Buděšínský, Miloš; Slaninová, Jiřina; Bednárová, Lucie; Hadravová, Romana; Straka, Jakub; Veverka, Václav; Čeřovský, Václav

    2016-04-22

    Venoms of hymenopteran insects have attracted considerable interest as a source of cationic antimicrobial peptides (AMPs). In the venom of the solitary bee Hylaeus signatus (Hymenoptera: Colletidae), we identified a new hexadecapeptide of sequence Gly-Ile-Met-Ser-Ser-Leu-Met-Lys-Lys-Leu-Ala-Ala-His-Ile-Ala-Lys-NH2. Named HYL, it belongs to the category of α-helical amphipathic AMPs. HYL exhibited weak antimicrobial activity against several strains of pathogenic bacteria and moderate activity against Candida albicans, but its hemolytic activity against human red blood cells was low. We prepared a set of HYL analogues to evaluate the effects of structural modifications on its biological activity and to increase its potency against pathogenic bacteria. This produced several analogues exhibiting significantly greater activity compared to HYL against strains of both Staphylococcus aureus and Pseudomonas aeruginosa even as their hemolytic activity remained low. Studying synergism of HYL peptides and conventional antibiotics showed the peptides act synergistically and preferentially in combination with rifampicin. Fluorescent dye propidium iodide uptake showed the tested peptides were able to facilitate entrance of antibiotics into the cytoplasm by permeabilization of the outer and inner bacterial cell membrane of P. aeruginosa. Transmission electron microscopy revealed that treatment of P. aeruginosa with one of the HYL analogues caused total disintegration of bacterial cells. NMR spectroscopy was used to elucidate the structure-activity relationship for the effect of amino acid residue substitution in HYL. PMID:26998557

  6. Vancomycin and High Level Aminoglycoside Resistance in Enterococcus spp. in a Tertiary Health Care Centre: A Therapeutic Concern

    Directory of Open Access Journals (Sweden)

    Seema Mittal

    2016-01-01

    Full Text Available Aims. This study was aimed at knowing the prevalence of vancomycin and high level aminoglycoside resistance in enterococcal strains among clinical samples. Study Design. It was an investigational study. Place and Duration of Study. It was conducted on 100 Enterococcus isolates, in the Department of Microbiology, Pt. BDS PGIMS, Rohtak, over a period of six months from July to December 2014. Methodology. Clinical specimens including urine, pus, blood, semen, vaginal swab, and throat swab were processed and Enterococcus isolates were identified by standard protocols. Antibiotic sensitivity testing of enterococci was performed using Kirby-Bauer disc diffusion method. Results. High level gentamicin resistance (HLGR was more common in urine samples (41.5% followed by blood (36% samples. High level streptomycin resistance (HLSR was more common in pus samples (52.6% followed by blood samples (36%. Resistance to vancomycin was maximum in blood isolates. Conclusion. Enterococci resistant to multiple antimicrobial agents have been recognized. Thus, it is crucial for laboratories to provide accurate antimicrobial resistance patterns for enterococci so that effective therapy and infection control measures can be initiated.

  7. Antibiotic usage in 2013 on a dairy CAFO in NY State, USA

    Directory of Open Access Journals (Sweden)

    Marie Doane

    2014-05-01

    Full Text Available Antimicrobial resistance is threatening humans and animals worldwide. Biosecurity and 1-year usage of antibiotics on a dairy concentrated animal feeding operation (CAFO in NY State, USA, were mapped: how much antibiotics were used, for what purpose, and whether any decrease could be warranted. Approximately 493 kg antibiotics was used, of which 376 kg was ionophores (monensin and lasalocides, 79 kg penicillin, 16.5 kg lincosamides, 8.0 kg aminoglycosides, 7.7 kg sulfamides, 3.4 kg cephalosporin, 2 kg macrolides, 0.7 kg amphenicols, and 0.1 kg fluoroquinolones. Usage reduction by 84% was realistic without compromising the animal welfare. Further reduction could be possible by improving the biosecurity and by utilizing antibiotic sensitivity testing.

  8. Cilia-Associated Genes Play Differing Roles in Aminoglycoside-Induced Hair Cell Death in Zebrafish

    Directory of Open Access Journals (Sweden)

    Tamara M. Stawicki

    2016-07-01

    Full Text Available Hair cells possess a single primary cilium, called the kinocilium, early in development. While the kinocilium is lost in auditory hair cells of most species it is maintained in vestibular hair cells. It has generally been believed that the primary role of the kinocilium and cilia-associated genes in hair cells is in the establishment of the polarity of actin-based stereocilia, the hair cell mechanotransduction apparatus. Through genetic screening and testing of candidate genes in zebrafish (Danio rerio we have found that mutations in multiple cilia genes implicated in intraflagellar transport (dync2h1, wdr35, ift88, and traf3ip, and the ciliary transition zone (cc2d2a, mks1, and cep290 lead to resistance to aminoglycoside-induced hair cell death. These genes appear to have differing roles in hair cells, as mutations in intraflagellar transport genes, but not transition zone genes, lead to defects in kinocilia formation and processes dependent upon hair cell mechanotransduction activity. These mutants highlight a novel role of cilia-associated genes in hair cells, and provide powerful tools for further study.

  9. Cilia-Associated Genes Play Differing Roles in Aminoglycoside-Induced Hair Cell Death in Zebrafish.

    Science.gov (United States)

    Stawicki, Tamara M; Hernandez, Liana; Esterberg, Robert; Linbo, Tor; Owens, Kelly N; Shah, Arish N; Thapa, Nihal; Roberts, Brock; Moens, Cecilia B; Rubel, Edwin W; Raible, David W

    2016-01-01

    Hair cells possess a single primary cilium, called the kinocilium, early in development. While the kinocilium is lost in auditory hair cells of most species it is maintained in vestibular hair cells. It has generally been believed that the primary role of the kinocilium and cilia-associated genes in hair cells is in the establishment of the polarity of actin-based stereocilia, the hair cell mechanotransduction apparatus. Through genetic screening and testing of candidate genes in zebrafish (Danio rerio) we have found that mutations in multiple cilia genes implicated in intraflagellar transport (dync2h1, wdr35, ift88, and traf3ip), and the ciliary transition zone (cc2d2a, mks1, and cep290) lead to resistance to aminoglycoside-induced hair cell death. These genes appear to have differing roles in hair cells, as mutations in intraflagellar transport genes, but not transition zone genes, lead to defects in kinocilia formation and processes dependent upon hair cell mechanotransduction activity. These mutants highlight a novel role of cilia-associated genes in hair cells, and provide powerful tools for further study.

  10. The antibiotic activity of some Brazilian medicinal plants Atividade antibiótica de algumas plantas medicinais brasileiras

    Directory of Open Access Journals (Sweden)

    Maria R. Ferreira de Lima

    2006-09-01

    Full Text Available The antibiotic activities of the ethanol extracts from 16 species of plants used in Brazilian folk medicine have been determined against Staphylococcus aureus, Micrococcus flavus, Bacillus cereus, B. subtilis, Salmonella enteretidis, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Serratia marcescens, Mycobacterium phlei, M. smegmatis and M. fortuitum, and the yeasts Candida albicans and C. krusei. Among 32 extracts assayed, only those from Lafoensia pacari and Pterodon polygalaeflorus showed activity against the bacterial strains, and none were active against the yeasts. The ethanolic extract from the leaves of L. pacari showed minimum inhibitory concentration (MIC values of 312.5 to 2500, 250, 625 and 1250 mg/mL, respectively, against eight different Gram-positive strains of Staphylococcus aureus, the Gram-negative Proteus mirabilis and the acid-fast bacilli Mycobacterium phlei, M. fortuitum and M. smegmatis. The ethanolic extract from the stem of L. pacari showed an MIC value of 625 mg/mL against S. aureus. Chemical analysis revealed that the crude extracts contained tannins, steroids, phenols, flavonoids, triterpenes and saponins: the activities were sufficiently high to present the possibility of future identification of the active components by bioassay-guided fractionation and purification.As atividades antibióticas de extratos etanólicos de 16 espécies de plantas usadas em medicina popular no Brasil foram determinadas contra Staphylococcus aureus, Micrococcus flavus, Bacillus cereus, B. subtilis, Salmonella enteretidis, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Serratia marcescens, Mycobacterium phlei, M. smegmatis e M. fortuitum, contra as leveduras Candida albicans e C. krusei. Entre os trinta e dois extratos testados, somente aqueles derivados de Lafoensia pacari e Pterodon polygalaeflorus mostraram atividade contra as cepas bacterianas e nenhum deles apresentou atividade contra as leveduras. O

  11. Augmenting the potency of third-line antibiotics with Berberis aristata: In vitro synergistic activity against carbapenem-resistant Escherichia coli.

    Science.gov (United States)

    Thakur, Pallavi; Chawla, Raman; Goel, Rajeev; Narula, Alka; Arora, Rajesh; Sharma, Rakesh Kumar

    2016-09-01

    The aim of this study was to analyse the in vitro synergistic antibacterial potential of an aquoethanolic extract of the stem bark of Berberis aristata (PTRC-2111-A) with third-line antibiotics against carbapenem-resistant Escherichia coli. PTRC-2111-A was prepared and was characterised using phytochemical- and bioactivity-based fingerprinting. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography-mass spectrometry (LC-MS) analyses were performed, and superoxide and hydroxyl scavenging activities were assessed in conjunction with in vitro antimicrobial efficacy testing against the test micro-organism. Analysis of drug combinations of PTRC-2111-A and third-line antibiotics was performed using CompuSyn software. PTRC-2111-A from B. aristata was found to have seven common functional groups in comparison with the pre-identified marker compound quercetin, and phytochemical quantitation analysis revealed the presence of 25.44% alkaloids. Moreover, PTRC-2111-A was found to contain isoquinoline alkaloids, namely berbamine, berberine, reticuline, jatrorrhizine, palmatine and piperazine, as elucidated in the LC-MS analysis. Analysis of combinations of PTRC -2111-A and antibiotics revealed synergistic behaviour [fractional inhibitory concentration index (FICI)1) was seen with ertapenem and meropenem. PMID:27530832

  12. Probiotic lactobacilli and bifidobacteria in a fermented milk product with added fruit preparation reduce antibiotic associated diarrhea and Helicobacter pylori activity.

    Science.gov (United States)

    de Vrese, Michael; Kristen, Holger; Rautenberg, Peter; Laue, Christiane; Schrezenmeir, Jürgen

    2011-11-01

    To investigate matrix-specifity of probiotic effects and particularly of the reduction of antibiotics-associated diarrhea, a controlled, randomized, double-blind study was performed, in which 88 Helicobacter pylori-infected but otherwise healthy subjects were given for eight weeks either a) a probiotic fruit yoghurt "mild" containing Lactobacillus acidophilus LA-5 plus Bifidobacterium lactis BB-12, n = 30), b) the same product but pasteurized after fermentation (n = 29) or c) milk acidified with lactic acid (control, n = 29). During week five, a Helicobacter eradication therapy was performed. Helicobacter activity was measured via 13C-2-urea breath tests and antibiotic-associated diarrhoea and other gastrointestinal complaints were recorded by validated questionnaires. In intervention group a, b and c the mean number of days with diarrhoea was 4, 10 and 10 (Pantibiotics treatment was -1·4 ± 1·1, -1·2 ± 1·1, 2·6 ± 1·1 points/four weeks (Pprobiotic bacteria but (rather) to components of acidified milk (most probably lactic acid). Fruit-yogurt-like fermented milk products with living probiotic bacteria significantly shorten the duration of antibiotics-associated diarrhoea and improve gastrointestinal complaints. Fruit yogurt-like fermented milk is a matrix suitable for probiotic bacteria.

  13. Evaluation of the antibiotic activity and genetic mutation of microorganisms in the effluent treated with the electron-beam from waste-water treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Hun; Nam, Ji Hyun; Shin, Ji Hye; Yun, Seo Yeon; Cho, Young Cheol; Oh, Kyoung hee [Chungbuk National University, Cheongju (Korea, Republic of)

    2011-04-15

    In this study, the residual concentrations and activities of antibiotics after UV or gamma-ray treatments were estimated, and the effect of irradiation of UV, gamma-ray, or electron beam was estimated on the survivability and less mutagenic effect on bacteria. The changes of bacterial communities and radiation resistant population in the effluent treated with UV and electron-beam were analyzed. The gamma-ray irradiation was more effective than UV in degradation of antibiotics. The extent of mutagenicity of electron-beam irradiation was less than those of UV or gamma-ray irradiations. The application of election-beam to the wastewater treatment system showed the high efficiency of destroying and removal effects on bacterial cells. The selective increase in population of radiation resistant bacteria was not observed. These results indicate that the application of ionizing radiation to the processes of wastewater treatment system will be suitable than UV irradiation because of its degradability of variable antibiotics, high removal rate of harmful bacteria, less mutagenicity of bacteria, and low selective effect on radiation resistant bacteria

  14. Evaluation of the antibiotic activity and genetic mutation of microorganisms in the effluent treated with the electron-beam from waste-water treatment plant

    International Nuclear Information System (INIS)

    In this study, the residual concentrations and activities of antibiotics after UV or gamma-ray treatments were estimated, and the effect of irradiation of UV, gamma-ray, or electron beam was estimated on the survivability and less mutagenic effect on bacteria. The changes of bacterial communities and radiation resistant population in the effluent treated with UV and electron-beam were analyzed. The gamma-ray irradiation was more effective than UV in degradation of antibiotics. The extent of mutagenicity of electron-beam irradiation was less than those of UV or gamma-ray irradiations. The application of election-beam to the wastewater treatment system showed the high efficiency of destroying and removal effects on bacterial cells. The selective increase in population of radiation resistant bacteria was not observed. These results indicate that the application of ionizing radiation to the processes of wastewater treatment system will be suitable than UV irradiation because of its degradability of variable antibiotics, high removal rate of harmful bacteria, less mutagenicity of bacteria, and low selective effect on radiation resistant bacteria

  15. Validation and Application of a Dried Blood Spot Assay for Biofilm-Active Antibiotics Commonly Used for Treatment of Prosthetic Implant Infections.

    Science.gov (United States)

    Knippenberg, Ben; Page-Sharp, Madhu; Salman, Sam; Clark, Ben; Dyer, John; Batty, Kevin T; Davis, Timothy M E; Manning, Laurens

    2016-08-01

    Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK)/pharmacodynamic (PD) studies in situations where venous blood sampling is logistically difficult. We sought to develop, validate, and apply a DBS assay for rifampin (RIF), fusidic acid (FUS), and ciprofloxacin (CIP). These antibiotics are considered active against organisms in biofilms and are therefore commonly used for the treatment of infections associated with prosthetic implants. A liquid chromatography-mass spectroscopy DBS assay was developed and validated, including red cell partitioning and thermal stability for each drug and the rifampin metabolite desacetyl rifampin (Des-RIF). Plasma and DBS concentrations in 10 healthy adults were compared, and the concentration-time profiles were incorporated into population PK models. The limits of quantification for RIF, Des-RIF, CIP, and FUS in DBS were 15 μg/liter, 14 μg/liter, 25 μg/liter, and 153 μg/liter, respectively. Adjusting for hematocrit, red cell partitioning, and relative recovery, DBS-predicted plasma concentrations were comparable to measured plasma concentrations for each antibiotic (r > 0.95; P < 0.0001), and Bland-Altman plots showed no significant bias. The final population PK estimates of clearance, volume of distribution, and time above threshold MICs for measured and DBS-predicted plasma concentrations were comparable. These drugs were stable in DBSs for at least 10 days at room temperature and 1 month at 4°C. The present DBS antibiotic assays are robust and can be used as surrogates for plasma concentrations to provide valid PK and PK/PD data in a variety of clinical situations, including therapeutic drug monitoring or studies of implant infections.

  16. Facts about Antibiotic Resistance

    Science.gov (United States)

    ... Recommendations Pediatric Treatment Recommendations Inpatient Healthcare Professionals Community Pharmacists Continuing Education & Curriculum Opportunities Weighing in on Antibiotic Resistance Improving Prescribing Outpatient Antibiotic Stewardship Interventions That Work Systematic Reviews ...

  17. Antibiotic / Antimicrobial Resistance Glossary

    Science.gov (United States)

    ... Recommendations Pediatric Treatment Recommendations Inpatient Healthcare Professionals Community Pharmacists Continuing Education & Curriculum Opportunities Weighing in on Antibiotic Resistance Improving Prescribing Outpatient Antibiotic Stewardship Interventions That Work Systematic Reviews ...

  18. Antibacterial and anti-biofilm activities of melittin and colistin, alone and in combination with antibiotics against Gram-negative bacteria.

    Science.gov (United States)

    Dosler, Sibel; Karaaslan, Elif; Alev Gerceker, A

    2016-04-01

    In vitro antibacterial and anti-biofilm activities of antimicrobial cationic peptides (AMPs) - melittin and colistin - both alone and in combination with antibiotics were evaluated against clinical isolates of Gram-negative bacteria. Minimum inhibitory concentration (MIC) and fractional inhibitory concentration (FIC) index were determined by the microbroth dilution and chequerboard techniques, respectively. The time-kill curve (TKC) method was used for determining the bactericidal activities of AMPs alone and in combination. Measurements of anti-biofilm activities were performed spectrophotometrically for both inhibition of attachment and 24-hour biofilm formation at MIC or subMIC. According to MIC90 values, the most active agents against Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae were colistin, imipenem and ciprofloxacin, respectively. In combination studies, synergistic effects were mostly seen with colistin-imipenem against E. coli and K. pneumoniae (50 and 54%, respectively), colistin-ciprofloxacin against P. aeruginosa (77%). In TKC studies, synergism was observed with almost all expected combinations, even more frequently than chequerboard method. All of the antimicrobial agents were able to inhibit attachment and 24-hour biofilm formation between 0-57% at 1/10 × MIC and 7-73% at 1 × or 1/10 × MIC, respectively. AMPs seem to be a good candidate for antimicrobial chemotherapy with their antibacterial and anti-biofilm activities as a single agent or in combination with antibiotics. PMID:25801062

  19. Study on aminoglycoside resistance and drug resistance gene of ESBLs-producing Escherichia coil%产超广谱β-内酰胺酶大肠埃希菌对氨基糖甙类药物耐药性及耐药基因研究

    Institute of Scientific and Technical Information of China (English)

    郑为平; 史伟峰

    2009-01-01

    Objective To investigate the characteristics of aminoglycoside resistance of extend-ed-spectrum β-lactamases(ESBLs)-producing Escherichia coli(E, cold and expression of aminoglyco-side-modifying enzyme genes. Methods The minimal inhibitory concentrations(MICs) of gentamicin,amikacin, kanamycin, tobramycin, netilmicin and neomycin for 37 strains of ESBLs-producing E. Coli were detected by agar dilution. In addition, six aminoglycoside-modifying enzyme genes were amplified by polymersae chain reaction(PCR) and verified by DNA sequencing. Results MIC and MIC90 of gentamicin, amikacin, kanamycin, tobramycin and netilmicin for 37 strains of ESBLs-producing E. Co-Il all excelled 256 μg/mL, the resistance rates of the above antibiotics were 78.4%, 45.9%, 72.9%,83.8%and 64.90%, respectively. However, neomycin still had powerful antibacterial activity. In ad-dition, five modifying enzyme genes, including aac(3)-Ⅱ , aac(6′)-Ⅰ b, aac(6′)-Ⅱ , ant(2″)-Ⅰ and ant(3″)- Ⅰ genes, were found in 37 isoaltes except aac(3)- Ⅰ , and their positive rates were 56.8%,27.0 %, 2.7 %, 5.4 % and 13. 5 %, respectively. Conclusion The aminoglycoside resistance of ES-BLs-producing E. Coil may be associated with the expression of aminoglycoside-modifying enzyme genes.%目的 研究产超广谱β-内酰胺酶(ESBLs)大肠埃希菌对氨基糖甙类药物的耐药特性及耐药基因表达.方法 用琼脂稀释法检测庆大霉素、阿米卡星、卡那霉素、妥布霉素、奈替米星和新霉素6种药物对37株产ESBLs大肠埃希菌的最低抑菌浓度.用PCR法检测5种氨基糖甙类药物修饰酶基因,并使用DNA测序加以证实.结果 庆大霉素、阿米卡星、卡那霉素、妥布霉素和奈替米星对37株大肠埃希菌MIC50、MIC90.均大于256 mg/L,其耐药率分别为78.4%、45.9%、72.9%、83.8%和64.9%,而新霉素仍具有较高的抗菌活性.从37株菌中检出5种修饰酶基因,aac(3)-Ⅱ、aac(6′)-Ⅰ b、aac(6′)-Ⅱ、ant(2

  20. Diurnal variations in the occurrence and the fate of hormones and antibiotics in activated sludge wastewater treatment in Oslo, Norway

    International Nuclear Information System (INIS)

    We present an assessment of the dynamics in the influent concentration of hormones (estrone, estriol) and antibiotics (trimethoprim, sulfamethoxazole, tetracycline, ciprofloxacin) in the liquid phase including the efficiency of biological municipal wastewater treatment. The concentration of estradiol, 17-α-ethinylestradiol, doxycycline, oxytetracycline, demeclocycline, chlortetracycline, cefuroxime, cyclophosphamide, and ifosfamide were below the limit of detection in all of the sewage samples collected within this study. Two different types of diurnal variation pattern were identified in the influent mass loads of selected antibiotics and hormones that effectively correlate with daily drug administration patterns and with the expected maximum human hormone release, respectively. The occurrence of natural hormones and antimicrobials, administered every 12 hours, shows a daily trend of decreasing contaminant mass load, having the maximum values in the morning hours. The occurrence of antibiotics, typically administered every 8 hours, indicates a daily peak value in samples collected under the highest hydraulic loading. The efficiency of biological removal of both hormones and antibiotics is shown to be limited. Compared to the values obtained in the influent samples, increased concentrations are observed in the biologically treated effluent for trimethoprim, sulfamethoxazole and ciprofloxacin, mainly as a result of deconjugation processes. Ciprofloxacin is shown as the predominant antimicrobial compound in the effluent, and it is present at quantities approximately 10 fold greater than the total mass of the other of the compounds due to poor removal efficiency and alternating solid-liquid partitioning behaviour. Our results suggest that, to increase the micro-pollutant removal and the chemical dosing efficiency in enhanced tertiary treatment, significant benefits can be derived from the optimisation of reactor design and the development of control schemes that

  1. Diurnal variations in the occurrence and the fate of hormones and antibiotics in activated sludge wastewater treatment in Oslo, Norway

    Energy Technology Data Exchange (ETDEWEB)

    Plosz, Benedek Gy., E-mail: benedek.plosz@niva.no [Norwegian Institute for Water Research, NIVA, Gaustadalleen 21, NO-0349, Oslo (Norway); Leknes, Henriette [Norwegian Institute for Air Research NILU, 2027 Kjeller (Norway); Liltved, Helge; Thomas, Kevin V. [Norwegian Institute for Water Research, NIVA, Gaustadalleen 21, NO-0349, Oslo (Norway)

    2010-03-15

    We present an assessment of the dynamics in the influent concentration of hormones (estrone, estriol) and antibiotics (trimethoprim, sulfamethoxazole, tetracycline, ciprofloxacin) in the liquid phase including the efficiency of biological municipal wastewater treatment. The concentration of estradiol, 17-{alpha}-ethinylestradiol, doxycycline, oxytetracycline, demeclocycline, chlortetracycline, cefuroxime, cyclophosphamide, and ifosfamide were below the limit of detection in all of the sewage samples collected within this study. Two different types of diurnal variation pattern were identified in the influent mass loads of selected antibiotics and hormones that effectively correlate with daily drug administration patterns and with the expected maximum human hormone release, respectively. The occurrence of natural hormones and antimicrobials, administered every 12 hours, shows a daily trend of decreasing contaminant mass load, having the maximum values in the morning hours. The occurrence of antibiotics, typically administered every 8 hours, indicates a daily peak value in samples collected under the highest hydraulic loading. The efficiency of biological removal of both hormones and antibiotics is shown to be limited. Compared to the values obtained in the influent samples, increased concentrations are observed in the biologically treated effluent for trimethoprim, sulfamethoxazole and ciprofloxacin, mainly as a result of deconjugation processes. Ciprofloxacin is shown as the predominant antimicrobial compound in the effluent, and it is present at quantities approximately 10 fold greater than the total mass of the other of the compounds due to poor removal efficiency and alternating solid-liquid partitioning behaviour. Our results suggest that, to increase the micro-pollutant removal and the chemical dosing efficiency in enhanced tertiary treatment, significant benefits can be derived from the optimisation of reactor design and the development of control schemes that

  2. Antibacterial activity of three newly-synthesized chalcones & synergism with antibiotics against clinical isolates of methicillin-resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Dragana D Bozic

    2014-01-01

    Interpretation & conclusions: o0 ur study demonstrated that three newly-synthesized chalcones exhibited significant anti-MRSA effect and synergism with non-β-lactam antibiotics. The most effective compound was 1,3-Bis-(2-hydroxy-phenyl-propenone. Our results provide useful information for future research of possible application of chalcones in combination with conventional anti-MRSA therapy as promising new antimicrobial agents.

  3. The sigma factor sigma s affects antibiotic production and biological control activity of Pseudomonas fluorescens Pf-5.

    OpenAIRE

    Sarniguet, A.; Kraus, J.; Henkels, M D; Muehlchen, A M; Loper, J E

    1995-01-01

    Pseudomonas fluorescens Pf-5, a rhizosphere-inhabiting bacterium that suppresses several soilborne pathogens of plants, produces the antibiotics pyrrolnitrin, pyoluteorin, and 2,4-diacetylphloroglucinol. A gene necessary for pyrrolnitrin production by Pf-5 was identified as rpoS, which encodes the stationary-phase sigma factor sigma s. Several pleiotropic effects of an rpoS mutation in Escherichia coli also were observed in an RpoS- mutant of Pf-5. These included sensitivities of stationary-p...

  4. Ocorrência e diversidade estrutural de metabólitos fúngicos com atividade antibiótica Occurrence and structural diversity of fungal metabolites with antibiotic activity

    Directory of Open Access Journals (Sweden)

    Jacqueline Aparecida Takahashi

    2008-01-01

    Full Text Available Several reasons motivated the development of new generations of antibiotics, such as their high ability to develop resistance to virtually all kinds of anti-infective agents and the crescent market demand for new drugs to treat special demanding patients. After penicillin discovery, several antibiotics were developed from fungal metabolites, since antibacterial secondary metabolites consists on a fungal endogenous protective mechanism against natural competitors. The aim of this review is to present the structural diversity of antibacterial and antifungal metabolites produced by fungi, mentioning sources of fungal isolates, cultivation process and details on the scope of their antibiotic activity.

  5. Molecular typing and differences in biofilm formation and antibiotic susceptibilities among Prototheca strains isolated in Italy and Brazil.

    Science.gov (United States)

    Morandi, S; Cremonesi, P; Capra, E; Silvetti, T; Decimo, M; Bianchini, V; Alves, A C; Vargas, A C; Costa, G M; Ribeiro, M G; Brasca, M

    2016-08-01

    Bovine mastitis caused by Prototheca is a serious and complex problem that accounts for high economic losses in the dairy industry. The main objective of this study was to identify and characterize at genetic level different Prototheca strains and provide the most complete data about protothecal antibiotic resistance. The study involves 46 isolates from Italian (13 strains) and Brazilian (33 strains) mastitic milk. These strains were identified by multiplex PCR and single strand conformation polymorphism analysis and characterized by randomly amplified polymorphic DNA (RAPD)-PCR. Moreover, biofilm production and antibiotic susceptibility were evaluated. Forty-two strains resulted as Prototheca zopfii genotype 2, whereas 4 isolates could belong to a potential new Prototheca species. The RAPD-PCR, performed with 3 primers (M13, OPA-4, and OPA-18), showed a notable heterogeneity among isolates and grouped the strains according to the species and geographical origin. Biofilm production was species-dependent and P. zopfii genotype 2 strains were classified as strong biofilm producers. In vitro antibiotic susceptibility tests indicated that Prototheca strains were susceptible to antibacterial drugs belonging to aminoglycosides group; the highest activity against Prototheca strains was observed in the case of colistin sulfate, gentamicin, and netilmicin (100% of susceptible strains). It is interesting to note that all the Italian P. zopfii genotype 2 strains showed lower minimum inhibitory concentration values than the Brazilian ones. Nisin showed more efficacy than lysozyme and potassium sorbate, inhibiting 31% of the strains. Results obtained in this study confirmed that RAPD-PCR is a rapid, inexpensive, and highly discriminating tool for Prototheca strains characterization and could give a good scientific contribution for better understanding the protothecal mastitis in dairy herd. PMID:27236754

  6. Impacts of human activities on distribution of sulfate-reducing prokaryotes and antibiotic resistance genes in marine coastal sediments of Hong Kong.

    Science.gov (United States)

    Guo, Feng; Li, Bing; Yang, Ying; Deng, Yu; Qiu, Jian-Wen; Li, Xiangdong; Leung, Kenneth My; Zhang, Tong

    2016-09-01

    Sulfate-reducing prokaryotes (SRPs) and antibiotic resistance genes (ARGs) in sediments could be biomarkers for evaluating the environmental impacts of human activities, although factors governing their distribution are not clear yet. By using metagenomic approach, this study investigated the distributions of SRPs and ARGs in marine sediments collected from 12 different coastal locations of Hong Kong, which exhibited different pollution levels and were classified into two groups based on sediment parameters. Our results showed that relative abundances of major SRP genera to total prokaryotes were consistently lower in the more seriously polluted sediments (P-value niche differentiation of SRPs and behavior of ARGs in marine coastal sediment. PMID:27297722

  7. Antibiotic efficacy is linked to bacterial cellular respiration

    OpenAIRE

    Lobritz, Michael A.; Belenky, Peter; Porter, Caroline B. M.; Gutierrez, Arnaud; Yang, Jason H.; Schwarz, Eric G.; Dwyer, Daniel J; Khalil, Ahmad S.; James J Collins

    2015-01-01

    The global burden of antibiotic resistance has created a demand to better understand the basic mechanisms of existing antibiotics. Of significant interest is how antibiotics may perturb bacterial metabolism, and how bacterial metabolism may influence antibiotic activity. Here, we study the interaction of bacteriostatic and bactericidal antibiotics, the two major phenotypic drug classes. Interestingly, the two classes differentially perturb bacterial cellular respiration, with major consequenc...

  8. Antibiotic activity of the extract of Punica granatum Linn. over bovine strains of Staphylococcus aureus Atividade antimicrobiana do extrato de Punica granatum Linn. em linhagens de Staphylococcus aureus de origem bovina

    OpenAIRE

    Maria A. R. Silva; Jane S. Higino; Jozinete V. Pereira; José P. Siqueira-Júnior; Maria S.V. Pereira

    2008-01-01

    Human and veterinary medicines have not been so well succeeded in order to achieving their goals concerning the treatment of infections for long term caused by Staphylococcus aureus linked to resistance development against antibiotic agents. The antibiotic activity of the Punica granatum Linn. fresh fruit pericarp extract was evaluated by the agar diffusion method on 38 S. aureus strains, isolated from apparently healthy lactating cows in farms situated in counties of the semi-arid region of ...

  9. Presence of Clostridium difficile and antibiotic and beta-lactamase activities in feces of volunteers treated with oral cefixime, oral cefpodoxime proxetil, or placebo.

    Science.gov (United States)

    Chachaty, E; Depitre, C; Mario, N; Bourneix, C; Saulnier, P; Corthier, G; Andremont, A

    1992-09-01

    Three groups of six healthy adult volunteers were randomly assigned to a treatment with 400 mg of oral cefpodoxime proxetil, oral cefixime, or placebo per day for 10 days. Informed consent was obtained from all volunteers. Clostridium difficile was not detected in the feces of any subject before treatment or at any time in the subjects in the placebo group. C. difficile was, however, detected in all subjects treated with cefpodoxime proxetil and in five of six treated with cefixime. Genomic DNA restriction patterns showed that the strains of C. difficile differed from one volunteer to another. Two subjects both shed different strains at different times during the 25-day surveillance period. All isolates were resistant to cefixime and cefpodoxime (MIC for 90% of strains, 256 and 512 mg/liter, respectively). Antibiotic activity was found in the feces of one volunteer treated with cefpodoxime proxetil and of four volunteers treated with cefixime. It was inversely correlated with the presence of fecal beta-lactamase activity. Intestinal side effects were limited to modifications of stool consistency, which occurred in only 3 of the 12 treated volunteers and did not lead to cessation of treatment. These modifications were significantly associated with the presence of fecal antibiotic activity (P less than 0.05) but not with the shedding of toxigenic or nontoxigenic strains of C. difficile or with the presence of toxin A in feces, which was detected only in one perfectly healthy treated volunteer. PMID:1416894

  10. Toward an Alternative Therapeutic Approach for Skin Infections: Antagonistic Activity of Lactobacilli Against Antibiotic-Resistant Staphylococcus aureus and Pseudomonas aeruginosa.

    Science.gov (United States)

    Hafez, Mohamed M; Maghrabi, Ibrahim A; Zaki, Noha M

    2013-09-01

    The wide spread of antimicrobial resistance has urged the need of alternative therapeutic approach. In this context, probiotic lactobacilli have been reported for the prevention and treatment of many gastrointestinal and urogenital infections. However, very little is known about their antagonistic activity against skin pathogens. Accordingly, the present study aimed to investigate the potential of lactobacilli to interfere with pathogenesis features of two antibiotic-resistant skin pathogens, namely methicillin-resistant Staphylococcus aureus and multiple-resistant Pseudomonas aeruginosa. A total of 49 lactobacilli were recovered, identified and tested for their antagonistic activities against the aforementioned pathogens. Of these, eight isolates were capable of blocking the adherence of pathogens to mammalian cells independent of the skin pathogen tested or model adopted. Moreover, three Lactobacillus isolates (LRA4, LC2 and LR5) effectively prevented the pathogen internalization into epithelial cells in addition to potentiating phagocyte-mediated pathogen killing. Interestingly, the lactobacilli LC2, LF9 and LRA4 markedly inhibited the growth of P. aeruginosa and S. aureus isolates in coculture experiments. Besides, the lactobacilli LRA4, LC2, LR5 and LF9 have counteracted pathogen cytotoxicity. Taken together, the present study revealed some inhibitory activities of lactobacilli against two antibiotic-resistant skin pathogens. Moreover, it revealed two lactobacilli, namely LC2 and LRA4, with antagonistic capacity against different virulence determinants of skin pathogens. These lactobacilli are considered promising probiotic candidates that may represent an alternative therapeutic approach for skin infections.

  11. Influence of linker length and composition on enzymatic activity and ribosomal binding of neomycin dimers.

    Science.gov (United States)

    Watkins, Derrick; Kumar, Sunil; Green, Keith D; Arya, Dev P; Garneau-Tsodikova, Sylvie

    2015-07-01

    The human and bacterial A site rRNA binding as well as the aminoglycoside-modifying enzyme (AME) activity against a series of neomycin B (NEO) dimers is presented. The data indicate that by simple modifications of linker length and composition, substantial differences in rRNA selectivity and AME activity can be obtained. We tested five different AMEs with dimeric NEO dimers that were tethered via triazole, urea, and thiourea linkages. We show that triazole-linked dimers were the worst substrates for most AMEs, with those containing the longer linkers showing the largest decrease in activity. Thiourea-linked dimers that showed a decrease in activity by AMEs also showed increased bacterial A site binding, with one compound (compound 14) even showing substantially reduced human A site binding. The urea-linked dimers showed a substantial decrease in activity by AMEs when a conformationally restrictive phenyl linker was introduced. The information learned herein advances our understanding of the importance of the linker length and composition for the generation of dimeric aminoglycoside antibiotics capable of avoiding the action of AMEs and selective binding to the bacterial rRNA over binding to the human rRNA.

  12. A nanoplex PCR assay for the rapid detection of vancomycin and bifunctional aminoglycoside resistance genes in Enterococcus species

    Directory of Open Access Journals (Sweden)

    Ravichandran Manickam

    2007-12-01

    Full Text Available Abstract Background Enterococci have emerged as a significant cause of nosocomial infections in many parts of the world over the last decade. The most common enterococci strains present in clinical isolates are E. faecalis and E. faecium which have acquired resistant to either gentamicin or vancomycin. The conventional culture test takes 2–5 days to yield complete information of the organism and its antibiotic sensitivity pattern. Hence our present study was focused on developing a nanoplex PCR assay for the rapid detection of vancomycin and bifunctional aminoglycoside resistant enterococci (V-BiA-RE. This assay simultaneously detects 8 genes namely 16S rRNA of Enterococcus genus, ddl of E. faecalis and E. faecium, aacA-aphD that encodes high level gentamicin resistance (HLGR, multilevel vancomycin resistant genotypes such as vanA, vanB, vanC and vanD and one internal control gene. Results Unique and specific primer pairs were designed to amplify the 8 genes. The specificity of the primers was confirmed by DNA sequencing of the nanoplex PCR products and BLAST analysis. The sensitivity and specificity of V-BiA-RE nanoplex PCR assay was evaluated against the conventional culture method. The analytical sensitivity of the assay was found to be 1 ng at the DNA level while the analytical specificity was evaluated with 43 reference enterococci and non-enterococcal strains and was found to be 100%. The diagnostic accuracy was determined using 159 clinical specimens, which showed that 97% of the clinical isolates belonged to E. faecalis, of which 26% showed the HLGR genotype, but none were vancomycin resistant. The presence of an internal control in the V-BiA-RE nanoplex PCR assay helped us to rule out false negative cases. Conclusion The nanoplex PCR assay is robust and can give results within 4 hours about the 8 genes that are essential for the identification of the most common Enterococcus spp. and their antibiotic sensitivity pattern. The PCR assay

  13. 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...

  14. 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...

  15. Emergence of aminoglycoside resistance genes aadA and aadE in the genus Campylobacter.

    OpenAIRE

    Pinto-Alphandary, H; Mabilat, C; Courvalin, P

    1990-01-01

    Resistance to streptomycin or spectinomycin or both in five Campylobacter coli strains, two Campylobacter jejuni strains, and a Campylobacter-like strain was studied by enzymatic assays and dot blot hybridization. Resistance was due to 6- or 3",9-aminoglycoside adenylyltransferases and to new types of phospho- and adenylyltransferases.

  16. A new aspect of aminoglycoside ototoxicity : impairment of cochlear dopamine release

    NARCIS (Netherlands)

    Gáborján, A; Halmos, G; Répássy, G; Vizi, E S

    2001-01-01

    Aminoglycoside ototoxicity is a well-documented process via several pathophysiological pathways. The protective role of cochlear dopamine, released from the lateral olivocochlear efferents, was implicated previously in case of ischemia or acoustic trauma, as it postsynaptically inhibits the effect o

  17. 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 me

  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

    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...

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

    NARCIS (Netherlands)

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

    2003-01-01

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

  20. 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...

  1. Hazard assessment of commonly used agricultural antibiotics on aquatic ecosystems.

    Science.gov (United States)

    Park, Sujung; Choi, Kyungho

    2008-08-01

    In this study, eleven commonly used antibiotics including sulfonamides, tetracyclines, aminoglycosides, fluoroquinolones, and beta-lactams were evaluated for their acute and chronic aquatic toxicities using standard test organisms e.g., Vibrio fischeri, Daphnia magna, Moina macrocopa, and Oryzias latipes. Among the antibiotics tested for acute toxicity, neomycin was most toxic followed by trimethoprim, sulfamethoxazole and enrofloxacin. Sulfamethazine, oxytetracycline, chlortetracycline, sulfadimethoxine and sulfathiazole were of intermediate toxicity, while ampicillin and amoxicillin were least toxic to the test organisms. There were no trends in sensitivity among test organisms or among different classes of the antibiotics. Only the beta-lactam class was the least toxic. In chronic toxicity test, neomycin affected reproduction and adult survival of D. magna and M. macrocopa with low mg/l levels exposure. Predicted no effect concentrations (PNECs) were derived from the acute and chronic toxicity information gleaned from this study and from literature. When the PNECs were compared with measured environmental concentrations (MECs) reported elsewhere for the test compounds, hazard quotients for sulfamethoxazole, sulfathiazole, chlortetracycline, oxytetracycline, and amoxicillin exceeded unity, which suggests potential ecological implication. Therefore, further studies including monitoring and detailed toxicological studies are required to assess potential ecological risk of these frequently used veterinary antibiotics. PMID:18449638

  2. Degradation kinetics and mechanism of β-lactam antibiotics by the activation of H2O2 and Na2S2O8 under UV-254nm irradiation.

    Science.gov (United States)

    He, Xuexiang; Mezyk, Stephen P; Michael, Irene; Fatta-Kassinos, Despo; Dionysiou, Dionysios D

    2014-08-30

    The extensive production and usage of antibiotics have led to an increasing occurrence of antibiotic residuals in various aquatic compartments, presenting a significant threat to both ecosystem and human health. This study investigated the degradation of selected β-lactam antibiotics (penicillins: ampicillin, penicillin V, and piperacillin; cephalosporin: cephalothin) by UV-254nm activated H2O2 and S2O8(2-) photochemical processes. The UV irradiation alone resulted in various degrees of direct photolysis of the antibiotics; while the addition of the oxidants improved significantly the removal efficiency. The steady-state radical concentrations were estimated, revealing a non-negligible contribution of hydroxyl radicals in the UV/S2O8(2-) system. Mineralization of the β-lactams could be achieved at high UV fluence, with a slow formation of SO4(2-) and a much lower elimination of total organic carbon (TOC). The transformation mechanisms were also investigated showing the main reaction pathways of hydroxylation (+16Da) at the aromatic ring and/or the sulfur atom, hydrolysis (+18Da) at the β-lactam ring and decarboxylation (-44Da) for the three penicillins. Oxidation of amine group was also observed for ampicillin. This study suggests that UV/H2O2 and UV/S2O8(2-) advanced oxidation processes (AOPs) are capable of degrading β-lactam antibiotics decreasing consequently the antibiotic activity of treated waters.

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

    Directory of Open Access Journals (Sweden)

    Aimée M Moore

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

  4. [Sensitivity of Pseudomonas chlororaphis to antibiotics and chemical tools of plant protection].

    Science.gov (United States)

    Shepelevich, V V; Kiprianova, E A; Iaroshenko, L V; Avdeeva, L V

    2012-01-01

    Examination of sensitivity of 10 Pseudomonas chlororaphis strains belonging to different subspecies to 54 antibiotics has shown that all studied representatives of Pchlororaphis subsp. chlororaphis, P. chlororaphis subsp. aureofaciens and Pchlororaphis subsp. aurantiaca were sensitive to aminoglycoside antibiotics and fluoroquinolones derivatives. Only part of studied strains has shown sensitivity to some beta-lactam antibiotics, imipeneme and meropeneme. In contrast to representatives of two other subspecies both strains of P. chlororaphis subsp. chlororaphis proved to be sensitive to chlortetracycline and cefepime that allows to consider this difference as the characteristic useful for differentiation. All studied P. chlororaphis strains were resistant to chemical fungicides (Scor and Svitch) and the insect growth regulators (Match, Lufox, Engio, Actellik). Resistance of bacteria to these herbicides gives evidence that their combined use is possible.

  5. [Emerging and important antibiotic resistance in Gram negative bacteria: epidemiology, theory and practice].

    Science.gov (United States)

    Nordmann, P; Poirel, L

    2014-04-23

    Emerging and clinically-relevant antibiotic resistance mechanisms among Gram-negative rods are the extended-spectrum beta-lactamases (ESBL), carbapenemases, and 16S RNA methylases conferring resistance to aminoglycosides. Those resistance determinants do confer multiresistance to antibiotics. They are found in Enterobacteriaceae (especially community-acquired isolates, Pseudomonas aeruginosa and Acinetobacter baumannii). Detection of ESBL-producing and carbapenemase-producing isolates rely on the use of rapid diagnostic techniques that have to be performed when a reduced susceptibility to 3rd/4th generation cephalosporins or to carbapenems is observed, respectively. Only an early detection of those emerging resistance traits may contribute to limit their nosocomial spread and to optimize the antibiotic stewardship.

  6. Gene Sequence Based Clustering Assists in Dereplication of Pseudoalteromonas luteoviolacea Strains with Identical Inhibitory Activity and Antibiotic Production

    DEFF Research Database (Denmark)

    Vynne, Nikolaj Grønnegaard; Månsson, Maria; Gram, Lone

    2012-01-01

    Some microbial species are chemically homogenous, and the same secondary metabolites are found in all strains. In contrast, we previously found that five strains of P. luteoviolacea were closely related by 16S rRNA gene sequence but produced two different antibiotic profiles. The purpose...... antibacterial profiles based on inhibition assays against Vibrio anguillarum and Staphylococcus aureus. To determine whether chemotype and inhibition profile are reflected by phylogenetic clustering we sequenced 16S rRNA, gyrB and recA genes. Clustering based on 16S rRNA gene sequences alone showed little...... correlation to chemotypes and inhibition profiles, while clustering based on concatenated 16S rRNA, gyrB, and recA gene sequences resulted in three clusters, two of which uniformly consisted of strains of identical chemotype and inhibition profile. A major time sink in natural products discovery is the effort...

  7. Characterization of microbial community and antibiotic resistance genes in activated sludge under tetracycline and sulfamethoxazole selection pressure.

    Science.gov (United States)

    Zhang, Yingying; Geng, Jinju; Ma, Haijun; Ren, Hongqiang; Xu, Ke; Ding, Lili

    2016-11-15

    To investigate the microbial community characteristics, antibiotic resistance genes (ARGs), and bioreactor effluent quality change under tetracycline (TC) and sulfamethoxazole (SMX) selection pressure, sequencing batch reactors (SBRs) were used with environmentally relevant concentration and high-level of TC and SMX concentrations (0, 5ppb, 50ppb and 10ppm). Chemical oxygen demand (COD) and ammonia nitrogen (NH4(+)N) removals appeared unchanged (p>0.05) with 5 and 50ppb, but decreased significantly with 10ppm (ptetG>sul2>tetA>intI1>tetS>tetC. Pearson correlation analysis showed most ARGs (tetA, tetC, tetG, tetK, tetM, sul1) were significantly correlated with intI1 (p<0.01). PMID:27395074

  8. Antimicrobial Activity and Antibiotic Sensitivity of Three Isolates of Lactic Acid Bacteria From Fermented Fish Product, Budu

    Directory of Open Access Journals (Sweden)

    Liasi, S. A.

    2009-01-01

    Full Text Available Three isolates of lactic acid bacteria (LAB from the fermented food product, Budu, were identified as genus lactobacillus (Lactobacillus casei LA17, Lactobacillus plantarum LA22 and L. paracasei LA02, and the highest population was Lb. paracasei LA02. The antibacterial agent produced by the isolates inhibited the growth of a range of gram-positive and gram-negative microorganisms. Antimicrobial sensitivity test to 18 different types of antibiotic were evaluated using the disc diffusion method. Inhibition zone diameter was measured and calculated from the means of five determinations and expressed in terms of resistance or susceptibility. All the LAB isolates were resistant to colestin sulphate, streptomycin, amikacin, norfloxacin, nalidixic acid, mecillinam, sulphanethoxazole/ trimethoprim, kanamycin, neomycin, bacitracin and gentamycin but susceptible to erythromycin, penicillin G, chloramphenicol, tetracycline, ampicillin and nitrofurantion.

  9. In-vitro activity of fosfomycin trometamol and some other antibiotics against Escherichia coli strains isolated from urinary tract infections

    Directory of Open Access Journals (Sweden)

    Alicem Tekin

    2011-09-01

    Full Text Available Objectives: In recent years, in our country and the world, susceptibility of uropathogenic E.coli strains to commonly used antibiotics in the treatment of urinary tract infections has decreased. That decreased susceptibility has been caused to treatment failure, need to change the empirical treatment, increase in prescription costs, prolongation of hospital stay, increased social costs, increased morbidity and mortality. In this study, determination of susceptibility to different variety of antibiotics and fosfomycin in urinary tract infection isolate E.coli were aimed.Materials and methods: The study included E.coli positive urine samples which had been sent to State Hospital Central Laboratory in Kızıltepe between August 2010 and December 2010. These isolates were obtained from patients who have microscopically 10/mm3 leukocyte in urine. In this study, we tested susceptibility of isolated E.coli to FOT (Fosfomycin, CIP(ciprofloxacin, IP (İmipenem, TZP (Piperasilin-Tazobactam, CAZ (Ceftazidim. According to CLSI criteria, susceptibility testing was performed by Kirby-Bauer disc diffusion method.Results: E.coli strains isolated from urine samples examined between August 2010 and December 2010, all were susceptible to fosfomisine. The resistance rates of E.coli strains to Ceftazidim, Ciprofloxacin, İmipenem, Piperacillin-Tazobactam were found respectively 33.3%, 49.1%, 36.8%, 45.6% (Table 1.Conclusions: Because of the high susceptibility rates of fosfomycin at community-acquired urinary tract infection, it can be preferred to the non-complicated urinary tract infections as an antimicrobial agent.

  10. ACCUMULATION OF THE ANTIBIOTIC PHENAZINE-1-CARBOXYLIC ACID IN THE RHIZOSPHERE OF DRYLAND WHEAT

    Science.gov (United States)

    Natural antibiotics are thought to function in microbial defense, fitness, competitiveness, biocontrol, communication and gene regulation activity, and antibiotic-producing species are commonly found in microbial communities throughout nature. However, the frequency and amount of antibiotic producti...

  11. Antibacterial and antibiotic-potentiation activities of the methanol extract of some cameroonian spices against Gram-negative multi-drug resistant phenotypes

    Directory of Open Access Journals (Sweden)

    Voukeng Igor K

    2012-06-01

    Full Text Available Abstract Background The present work was designed to evaluate the antibacterial properties of the methanol extracts of eleven selected Cameroonian spices on multi-drug resistant bacteria (MDR, and their ability to potentiate the effect of some common antibiotics used in therapy. Results The extract of Cinnamomum zeylanicum against Escherichia coli ATCC 8739 and AG100 strains showed the best activities, with the lowest minimal inhibitory concentration (MIC of 64 μg/ml. The extract of Dorstenia psilurus was the most active when tested in the presence of an efflux pump inhibitor, phenylalanine Arginine-β- Naphtylamide (PAβN, a synergistic effect being observed in 56.25 % of the tested bacteria when it was combined with Erythromycin (ERY. Conclusion The present work evidently provides information on the role of some Cameroonian spices in the fight against multi-resistant bacteria.

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

    Directory of Open Access Journals (Sweden)

    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. Kinetics of kill of bacterial conjunctivitis isolates with moxifloxacin, a fluoroquinolone, compared with the aminoglycosides tobramycin and gentamicin

    Directory of Open Access Journals (Sweden)

    Rudolph S Wagner

    2010-01-01

    Full Text Available Rudolph S Wagner1, David B Granet2, Steven J Lichtenstein3, Tiffany Jamison4, Joseph J Dajcs4, Robert D Gross5, Paul Cockrum41New Jersey Medical School, Newark, NJ, USA; 2Ratner Children’s Eye Center, University of California – San Diego, La Jolla, CA, USA; 3University of Illinois College of Medicine at Peoria, Peoria, Illinois, USA; 4Alcon Research, Ltd, Fort Worth, TX, USA; 5Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USAPurpose: To compare the kinetics and speed of kill of Streptococcus pneumoniae and Haemophilus influenzae on exposure to three topical ophthalmic antibiotic solutions.Materials and methods: Bacterial conjunctivitis isolates of S. pneumoniae and H. influenzae were exposed to 1:1000 dilutions of moxifloxacin 0.5%, tobramycin 0.3%, gentamicin 0.3%, and water (control. At 15, 30, 60, 120, and 180 minutes after exposure, aliquots were collected, cells were cultured, and viable cell counts were determined using standard microbiological methods.Results: Moxifloxacin achieved 99.9% kill (3-log reduction at approximately 2 hours for S. pneumoniae and at 15 minutes for H. influenzae. Tobramycin and gentamicin did not achieve 3-log reduction of S. pneumoniae during the 180-minute study period. An increase in bacterial growth was noted for these isolates. Gentamicin took more than 120 minutes to achieve the 3-log reduction of H. influenzae and tobramycin did not reach the 3-log reduction of this pathogen during the 180-minute study period.Conclusion: Moxifloxacin killed S. pneumoniae and H. influenzae in vitro faster than tobramycin and gentamicin, suggesting its potential clinical benefit as a first-line treatment for bacterial conjunctivitis to minimize patient symptoms and to limit the contagiousness of the disease.Keywords: kinetics of kill, bacterial conjunctivitis, in vitro, Streptococcus pneumoniae, Haemophilus influenzae, fluoroquinolones, aminoglycosides

  14. Antibiotic research and development: business as usual?

    Science.gov (United States)

    Harbarth, S; Theuretzbacher, U; Hackett, J

    2015-01-01

    The global burden of antibiotic resistance is tremendous and, without new anti-infective strategies, will continue to increase in the coming decades. Despite the growing need for new antibiotics, few pharmaceutical companies today retain active antibacterial drug discovery programmes. One reason is that it is scientifically challenging to discover new antibiotics that are active against the antibiotic-resistant bacteria of current clinical concern. However, the main hurdle is diminishing economic incentives. Increased global calls to minimize the overuse of antibiotics, the cost of meeting regulatory requirements and the low prices of currently marketed antibiotics are strong deterrents to antibacterial drug development programmes. New economic models that create incentives for the discovery of new antibiotics and yet reconcile these incentives with responsible antibiotic use are long overdue. DRIVE-AB is a €9.4 million public-private consortium, funded by the EU Innovative Medicines Initiative, that aims to define a standard for the responsible use of antibiotics and to develop, test and recommend new economic models to incentivize investment in producing new anti-infective agents. PMID:25673635

  15. Mutation of Salmonella paratyphi A conferring cross-resistance to several groups of antibiotics by decreased permeability and loss of invasiveness.

    OpenAIRE

    Gutmann, L; Billot-Klein, D; Williamson, R.; Goldstein, F W; Mounier, J; Acar, J F; Collatz, E

    1988-01-01

    A spontaneous one-step mutant of Salmonella paratyphi A selected on ampicillin showed cross-resistance to all beta-lactam antibiotics except imipenem and to aminoglycosides, chloramphenicol, tetracycline, trimethoprim, and quinolones. It also grew as small colonies. Examination of the cell envelope of the mutant showed a quantitative decrease in three major outer membrane proteins of 40.6, 39.6 (presumably porins), and 24 kilodaltons and quantitative as well as qualitative modifications in th...

  16. Survey of Intraocular Antibiotics Prophylaxis Practice after Open Globe Injury in China

    Science.gov (United States)

    Tan, Junlian; Yang, Yao; Yuan, Zhaohui; Lin, Xiaofeng

    2016-01-01

    Purpose To elucidate the Chinese practice of intraocular antibiotics administration for prophylaxis after open globe injury. Methods A cross-sectional questionnaire survey was performed online by scanning a Quickmark (QR) code with smartphones at the 20th Chinese National Conference of Ocular Trauma in November 2014. Results A total of 153 (30.6%) of all participators at the conference responded. Of the respondents, 20.9% were routinely administered with prophylactic intraocular injection of antibiotics at the conclusion of the primary eye repair, and 56.9% were used only in cases with high risk of endophthalmitis development. The intraocular route of delivery was mainly included with intracameral injection (47.9%) and intravitreal injection (42.0%). Cephalosporins (53.8%) and vancomycin (42.0%) were the main choices of antibiotic agents, followed by fluoroquinolones (24.3%), and aminoglycosides (13.4%). Only 21.9% preferred a combination of two or more two drugs routinely. In addition, significantly more respondents from the referral eye hospital (92.7%) replied using intraocular antibiotics injection for prophylaxis compared to those respondents from the primary hospital (69.4%) (p = 0.001, Fisher’s exact test). Conclusions Intraocular antibiotics injection for post-traumatic endophthalmitis prophylaxis is widely used in China. However, the choice of antibiotic agents and the intraocular route of delivery vary. A well-designed clinical trial is needed to establish a standardized protocol of intraocular antibiotics administration for post-traumatic endophthalmitis prophylaxis. PMID:27275777

  17. Survey of Intraocular Antibiotics Prophylaxis Practice after Open Globe Injury in China.

    Directory of Open Access Journals (Sweden)

    Bingsheng Lou

    Full Text Available To elucidate the Chinese practice of intraocular antibiotics administration for prophylaxis after open globe injury.A cross-sectional questionnaire survey was performed online by scanning a Quickmark (QR code with smartphones at the 20th Chinese National Conference of Ocular Trauma in November 2014.A total of 153 (30.6% of all participators at the conference responded. Of the respondents, 20.9% were routinely administered with prophylactic intraocular injection of antibiotics at the conclusion of the primary eye repair, and 56.9% were used only in cases with high risk of endophthalmitis development. The intraocular route of delivery was mainly included with intracameral injection (47.9% and intravitreal injection (42.0%. Cephalosporins (53.8% and vancomycin (42.0% were the main choices of antibiotic agents, followed by fluoroquinolones (24.3%, and aminoglycosides (13.4%. Only 21.9% preferred a combination of two or more two drugs routinely. In addition, significantly more respondents from the referral eye hospital (92.7% replied using intraocular antibiotics injection for prophylaxis compared to those respondents from the primary hospital (69.4% (p = 0.001, Fisher's exact test.Intraocular antibiotics injection for post-traumatic endophthalmitis prophylaxis is widely used in China. However, the choice of antibiotic agents and the intraocular route of delivery vary. A well-designed clinical trial is needed to establish a standardized protocol of intraocular antibiotics administration for post-traumatic endophthalmitis prophylaxis.

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

    Science.gov (United States)

    Molina, Lázaro; Udaondo, Zulema; Duque, Estrella; Fernández, Matilde; Molina-Santiago, Carlos; Roca, Amalia; Porcel, Mario; de la Torre, Jesús; Segura, Ana; Plesiat, Patrick; Jeannot, Katy; Ramos, Juan-Luis

    2014-01-01

    Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267) kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts. PMID:24465371

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

    Directory of Open Access Journals (Sweden)

    Lázaro Molina

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

  20. Penetration barrier contributes to bacterial biofilm-associated resistance against only select antibiotics, and exhibits genus-, strain- and antibiotic-specific differences.

    Science.gov (United States)

    Singh, Rachna; Sahore, Simmi; Kaur, Preetinder; Rani, Alka; Ray, Pallab

    2016-08-01

    Bacterial biofilms are implicated in a wide range of implant-based and chronic infections. These infections are often associated with adverse therapeutic outcomes, owing to the decreased antibiotic susceptibility of biofilms compared with their planktonic counterparts. This altered biofilm susceptibility has been attributed to multiple factors, including a reduced antibiotic penetration. Although several studies have addressed the role of penetration barrier in biofilm-associated drug resistance, it remains inconclusive. This study was done to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae, using an agar disk diffusion assay. Penetration capacity of six antimicrobial drugs from different classes (β-lactams, aminoglycosides, tetracyclines, phenicols, fluoroquinolones and glycopeptides) through biofilms formed by standard strains and clinical isolates from catheter-related bloodstream infections (CRBSI) was elucidated by measuring their growth-inhibition zones in lawn cultures on Mueller-Hinton agar, following diffusion of an antibiotic from an overlying disk through their biofilm to the agar medium. Penetration of only select antimicrobials (vancomycin and chloramphenicol) was hindered through biofilms. There was considerable variation in biofilm-permeating capacity depending upon the genus, strain/CRBSI isolate and antibiotic tested. Furthermore, antibiotics failed to kill the biofilm cells independent of penetration, indicating that other factors contributed substantially to biofilm resistance. PMID:27402781

  1. Penetration barrier contributes to bacterial biofilm-associated resistance against only select antibiotics, and exhibits genus-, strain- and antibiotic-specific differences.

    Science.gov (United States)

    Singh, Rachna; Sahore, Simmi; Kaur, Preetinder; Rani, Alka; Ray, Pallab

    2016-08-01

    Bacterial biofilms are implicated in a wide range of implant-based and chronic infections. These infections are often associated with adverse therapeutic outcomes, owing to the decreased antibiotic susceptibility of biofilms compared with their planktonic counterparts. This altered biofilm susceptibility has been attributed to multiple factors, including a reduced antibiotic penetration. Although several studies have addressed the role of penetration barrier in biofilm-associated drug resistance, it remains inconclusive. This study was done to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae, using an agar disk diffusion assay. Penetration capacity of six antimicrobial drugs from different classes (β-lactams, aminoglycosides, tetracyclines, phenicols, fluoroquinolones and glycopeptides) through biofilms formed by standard strains and clinical isolates from catheter-related bloodstream infections (CRBSI) was elucidated by measuring their growth-inhibition zones in lawn cultures on Mueller-Hinton agar, following diffusion of an antibiotic from an overlying disk through their biofilm to the agar medium. Penetration of only select antimicrobials (vancomycin and chloramphenicol) was hindered through biofilms. There was considerable variation in biofilm-permeating capacity depending upon the genus, strain/CRBSI isolate and antibiotic tested. Furthermore, antibiotics failed to kill the biofilm cells independent of penetration, indicating that other factors contributed substantially to biofilm resistance.

  2. Association between clinical antibiotic resistance and susceptibility of Pseudomonas in the cystic fibrosis lung

    Science.gov (United States)

    Jansen, Gunther; Mahrt, Niels; Tueffers, Leif; Barbosa, Camilo; Harjes, Malte; Adolph, Gernot; Friedrichs, Anette; Krenz-Weinreich, Annegret; Rosenstiel, Philip; Schulenburg, Hinrich

    2016-01-01

    Background and objectives: Cystic fibrosis patients suffer from chronic lung infections that require long-term antibiotic therapy. Pseudomonas readily evolve resistance, rendering antibiotics ineffective. In vitro experiments suggest that resistant bacteria may be treated by exploiting their collateral sensitivity to other antibiotics. Here, we investigate correlations of sensitivity and resistance profiles of Pseudomonas aeruginosa that naturally adapted to antibiotics in the cystic fibrosis lung. Methodology: Resistance profiles for 13 antibiotics were obtained using broth dilution, E-test and VITEK mass spectroscopy. Genetic variants were determined from whole-genome sequences and interrelationships among isolates were analyzed using 13 MLST loci. Result: Our study focused on 45 isolates from 13 patients under documented treatment with antibiotics. Forty percent of these were clinically resistant and 15% multi-drug resistant. Colistin resistance was found once, despite continuous colistin treatment and even though colistin resistance can readily evolve experimentally in the laboratory. Patients typically harbored multiple genetically and phenotypically distinct clones. However, genetically similar clones often had dissimilar resistance profiles. Isolates showed mutations in genes encoding cell wall synthesis, alginate production, efflux pumps and antibiotic modifying enzymes. Cross-resistance was commonly observed within antibiotic classes and between aminoglycosides and β-lactam antibiotics. No evidence was found for consistent phenotypic resistance to one antibiotic and sensitivity to another within one genotype. Conclusions and implications: Evidence supporting potential collateral sensitivity in clinical P. aeruginosa isolates remains equivocal. However, cross-resistance within antibiotic classes is common. Colistin therapy is promising since resistance to it was rare despite its intensive use in the studied patients. PMID:27193199

  3. Antibiotic research and development: business as usual?

    NARCIS (Netherlands)

    Harbarth, S.; Theuretzbacher, U.; Hackett, J.; Hulscher, M.

    2015-01-01

    The global burden of antibiotic resistance is tremendous and, without new anti-infective strategies, will continue to increase in the coming decades. Despite the growing need for new antibiotics, few pharmaceutical companies today retain active antibacterial drug discovery programmes. One reason is

  4. Know When Antibiotics Work

    Centers for Disease Control (CDC) Podcasts

    2015-04-15

    This podcast provides a brief background about antibiotics and quick tips to help prevent antibiotic resistance.  Created: 4/15/2015 by Division of Bacterial Diseases (DBD), National Center for Immunization and Respiratory Disease (NCIRD), Get Smart: Know When Antibiotics Work Program.   Date Released: 4/16/2015.

  5. Strengthening Control of Antibiotics

    Institute of Scientific and Technical Information of China (English)

    EthelLu

    2005-01-01

    IT is a well-known fact that buy-ng guns is much easier than purchasing antibiotics in the United States. In China, however, the situation is different. According to a recent WHO survey,about 80 percent of Chinese inpatients take antibiotic medicines, and 58 percent of them are prescribed multifunctional antibiotics,

  6. 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.

  7. Effect of clavulanic acid on activity of beta-lactam antibiotics in Serratia marcescens isolates producing both a TEM beta-lactamase and a chromosomal cephalosporinase.

    Science.gov (United States)

    Bush, K; Flamm, R K; Ohringer, S; Singer, S B; Summerill, R; Bonner, D P

    1991-01-01

    An isolate of Serratia marcescens that produced both an inducible chromosomal and a plasmid-mediated TEM-1 beta-lactamase was resistant to ampicillin and amoxicillin and also demonstrated decreased susceptibility to extended-spectrum beta-lactam antibiotics (ESBAs). Clavulanic acid did not lower the MICs of the ESBAs, but it decreased the MICs of the penicillins. The TEM-1-producing plasmid was transferred to a more susceptible S. marcescens strain that produced a well-characterized inducible chromosomal beta-lactamase. The MICs of the ESBAs remained at a low level for the transconjugant. Ampicillin and amoxicillin which were good substrates for the plasmid-mediated enzyme, were not well hydrolyzed by the chromosomal enzymes; the ESBAs were hydrolyzed slowly by all the enzymes. When each of the S. marcescens strains was grown with these beta-lactam antibiotics, at least modest increases in chromosomal beta-lactamase activity were observed. When organisms were grown in the presence of clavulanic acid and an ESBA, no enhanced induction was observed. The increases in the MICs of the ESBAs observed for the initial clinical isolate may have been due to a combination of low inducibility, slow hydrolysis, and differences in permeability between the S. marcescens isolates. When clavulanic acid and a penicillin were added to strains that produced both a plasmid-mediated TEM and a chromosomal beta-lactamase, much higher levels of chromosomal beta-lactamase activity were present than were observed in cultures induced by the penicillin alone. This was due to the higher levels of penicillin that were available for induction as a result of inhibition of the TEM enzyme by clavulanate. Images PMID:1803992

  8. Aquaculture changes the profile of antibiotic resistance and mobile genetic element associated genes in Baltic Sea sediments.

    Science.gov (United States)

    Muziasari, Windi I; Pärnänen, Katariina; Johnson, Timothy A; Lyra, Christina; Karkman, Antti; Stedtfeld, Robert D; Tamminen, Manu; Tiedje, James M; Virta, Marko

    2016-04-01

    Antibiotics are commonly used in aquaculture and they can change the environmental resistome by increasing antibiotic resistance genes (ARGs). Sediment samples were collected from two fish farms located in the Northern Baltic Sea, Finland, and from a site outside the farms (control). The sediment resistome was assessed by using a highly parallel qPCR array containing 295 primer sets to detect ARGs, mobile genetic elements and the 16S rRNA gene. The fish farm resistomes were enriched in transposon and integron associated genes and in ARGs encoding resistance to antibiotics which had been used to treat fish at the farms. Aminoglycoside resistance genes were also enriched in the farm sediments despite the farms not having used aminoglycosides. In contrast, the total relative abundance values of ARGs were higher in the control sediment resistome and they were mainly genes encoding efflux pumps followed by beta-lactam resistance genes, which are found intrinsically in many bacteria. This suggests that there is a natural Baltic sediment resistome. The resistome associated with fish farms can be from native ARGs enriched by antibiotic use at the farms and/or from ARGs and mobile elements that have been introduced by fish farming. PMID:26976842

  9. Do antibiotics have environmental side-effects? Impact of synthetic antibiotics on biogeochemical processes.

    Science.gov (United States)

    Roose-Amsaleg, Céline; Laverman, Anniet M

    2016-03-01

    Antibiotic use in the early 1900 vastly improved human health but at the same time started an arms race of antibiotic resistance. The widespread use of antibiotics has resulted in ubiquitous trace concentrations of many antibiotics in most environments. Little is known about the impact of these antibiotics on microbial processes or "non-target" organisms. This mini-review summarizes our knowledge of the effect of synthetically produced antibiotics on microorganisms involved in biogeochemical cycling. We found only 31 articles that dealt with the effects of antibiotics on such processes in soil, sediment, or freshwater. We compare the processes, antibiotics, concentration range, source, environment, and experimental approach of these studies. Examining the effects of antibiotics on biogeochemical processes should involve environmentally relevant concentrations (instead of therapeutic), chronic exposure (versus acute), and monitoring of the administered antibiotics. Furthermore, the lack of standardized tests hinders generalizations regarding the effects of antibiotics on biogeochemical processes. We investigated the effects of antibiotics on biogeochemical N cycling, specifically nitrification, denitrification, and anammox. We found that environmentally relevant concentrations of fluoroquinolones and sulfonamides could partially inhibit denitrification. So far, the only documented effects of antibiotic inhibitions were at therapeutic doses on anammox activities. The most studied and inhibited was nitrification (25-100 %) mainly at therapeutic doses and rarely environmentally relevant. We recommend that firm conclusions regarding inhibition of antibiotics at environmentally relevant concentrations remain difficult due to the lack of studies testing low concentrations at chronic exposure. There is thus a need to test the effects of these environmental concentrations on biogeochemical processes to further establish the possible effects on ecosystem functioning.

  10. Aminoglycoside Efflux in Pseudomonas aeruginosa: Involvement of Novel Outer Membrane Proteins

    OpenAIRE

    Jo, James T. H.; Brinkman, Fiona S.L.; Hancock, Robert E W

    2003-01-01

    The expression of tripartite multidrug efflux pumps such as MexA-MexB-OprM in Pseudomonas aeruginosa contributes to intrinsic resistance to a wide variety of antimicrobials, including β-lactams, chloramphenicol, macrolides, quinolones, and tetracycline. The MexX-MexY linker-pump combination has been shown to be involved in intrinsic resistance to aminoglycosides, but the identity of the cognate outer membrane channel component remains under debate. Fourteen uncharacterized OprM homologs ident...

  11. Synthesis of 4′-aminopantetheine and derivatives to probe aminoglycoside N-6′-acetyltransferase

    OpenAIRE

    Yan, Xuxu; Akinnusi, T. Olukayode; Larsen, Aaron T.; Auclair, Karine

    2011-01-01

    A convenient synthesis of 4′-aminopantetheine from commercial D-pantethine is reported. The amino group was introduced by reductive amination in order to avoid substitution at a sterically congested position. Derivatives of 4′-aminopantetheine were also prepared to evaluate the effect of O-to-N substitution on inhibitors of the resistance-causing enzyme aminoglycoside N-6′-acetyltransferase. The biological results combined with docking studies indicate that in spite of its reported unusual fl...

  12. Suppressive Activity of a Macrolide Antibiotic, Roxithromycin, on Pro-Inflammatory Cytokine Production in Vitro and in Vivo

    Directory of Open Access Journals (Sweden)

    H. Suzaki

    1999-01-01

    Full Text Available This study was designed to examine the influence of a macrolide antibiotic, roxithromycin (RXM, on the production of pro-inflammatory cytokines, interleukin (IL-1β and tumor necrosis factor (TNF-α. In the first experiments, we examined the effect of RXM on in vitro cytokine production from lipopolysaccharide (LPS-stimulated human peripheral blood monocytes. The monocytes were cultured in the presence of various doses of the agent. After 24 h, the culture supernatants were obtained and assayed for IL-1β and TNF-α contents by enzyme-linked immunosorbent assay. RXM suppressed the in vitro production of IL-1β and TNF-α in response to LPS stimulation. This was dose dependent and first noted at a concentration of as little as 0.05 μg/ml, which is much lower than therapeutic blood levels. In the second part of the experiments, we examined the influence of RXM on the appearance of IL-1β and TNF-α in mouse lung extract induced by LPS inhalation. RXM was administered orally into BALB/c mice at a single dose of 2.5 mg/kg once a day for 5-12 weeks. These mice were then instilled with LPS into the trachea and examined for the presence of cytokines in aqueous lung extracts. Pretreatment of mice with RXM for 5 weeks did not influence of the appearance of both IL-1β and TNF-α in aqueous lung extracts. However, pretreatment for more than 7 weeks dramatically suppressed the cytokine appearance in the extracts.

  13. LOWER DOSE OF AMINOGLYCOSIDE OTOTOXIC EXPOSURE CAUSES PRESYNAPTIC ALTERATIONS ASSOICATED WITH HEARING LOSS

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; WANG Xiaoyu; LI Sijun; TANG Siquan; XU Yice; WANG Xuefeng; SUN Jianhe; YANG Weiyan; YANG Shiming

    2014-01-01

    Objective To study presynaptic alternations of cochlear ribbons arising from aminoglycoside ototoxic stimuli in C57BL/6J mice. Methods Animals were injected with low dose gentamicin (100 mg/kg/day) for 14 days, From the 14th to 28th days, the mice were maintained free of gentamicin treatment. Immunohisto-chemistry labeling was employed to trace RIBEYE, a major presynaptic componment of ribbon synapses. RIBEYE/CtBP2 expression levels were assessed and compared with hearing threshold shifts. Auditory func-tion was assessed by auditory brainstem responses. The stereocilia of outer hair cells (OHCs) and IHCs was examined by scanning electron microscopy (SEM). Results Hearing thresholds were elevated with peak hearing loss observed on the 7th day after gentamicin exposure, followed by improvement after the 7th day. RIBEYE/CtBP2 expression directly correlated with observed hearing threshold shifts. Strikingly, we did not see any obvious changes in stereocilia in both OHCs and IHCs until the 28th day. Mild changes in stereocil-ia were only observed in OHCs on the 28th day. Conclusions These findings indicate that presynapse co-chlear ribbons, rather than stereocilia, may be sensitive to aminoglycoside ototoxic exposure in mice cochle-ae. A pattern of RIBEYE/CtBP2 expression changes seems to parallel hearing threshold shifts and suggests presynaptic response properties to lower dosage of aminoglycoside ototoxic stimuli.

  14. Potent activity of the lichen antibiotic (+)-usnic acid against clinical isolates of vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus

    Science.gov (United States)

    Elo, Hannu; Matikainen, Jorma; Pelttari, Eila

    2007-06-01

    Vancomycin-resistant enterococci (VRE) and methicillin-resistant staphylococci, most notably methicillin-resistant Staphylococcus aureus (MRSA), are serious clinical problems. The antibiotic arsenal available against them is limited, and new mutants worsen the situation. We studied the activity of (+)-usnic acid, an old lichen-derived drug, and its sodium salt against clinical isolates of VRE and MRSA using the agar diffusion and minimal inhibitory concentration (MIC) methods. The acid and, especially, the sodium salt had potent antimicrobial activity against all clinical isolates of VRE and MRSA studied. The MIC values of the sodium salt against VRE strains ranged between 4 and 16 μg/ml (1-day test) and between 4 and 31 μg/ml (2-day test), being below 8 μg/ml for most strains. The salt had potent activity even against those strains that were not inhibited by ampicillin (125 μg/ml), and it never lost its activity after 24 h, in contrast to ampicillin. Thus, in spite of the fact that usnic acid can in some cases cause serious toxicity, it and its salts may be worth considering in clinical practice in cases where other therapies have failed or the microbe is resistant toward other agents.

  15. Antibiotic lock therapy: review of technique and logistical challenges

    Directory of Open Access Journals (Sweden)

    Justo JA

    2014-12-01

    Full Text Available Julie Ann Justo, P Brandon Bookstaver Department of Clinical Pharmacy and Outcomes Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC, USA Abstract: Antibiotic lock therapy (ALT for the prevention and treatment of catheter-related bloodstream infections is a simple strategy in theory, yet its real-world application may be delayed or avoided due to technical questions and/or logistical challenges. This review focuses on these latter aspects of ALT, including preparation information for a variety of antibiotic lock solutions (ie, aminoglycosides, beta-lactams, fluoroquinolones, folate antagonists, glycopeptides, glycylcyclines, lipopeptides, oxazolidinones, polymyxins, and tetracyclines and common clinical issues surrounding ALT administration. Detailed data regarding concentrations, additives, stability/compatibility, and dwell times are summarized. Logistical challenges such as lock preparation procedures, use of additives (eg, heparin, citrate, or ethylenediaminetetraacetic acid, timing of initiation and therapy duration, optimal dwell time and catheter accessibility, and risks of ALT are also described. Development of local protocols is recommended in order to avoid these potential barriers and encourage utilization of ALT where appropriate. Keywords: antibiotic lock, biofilm, bacteremia, catheter-related bloodstream infection

  16. Estimation of the use of antibiotics in the small ruminant industry in The Netherlands in 2011 and 2012.

    Directory of Open Access Journals (Sweden)

    Inge Santman-Berends

    Full Text Available The aim of this study was to estimate the quantity of antibiotics and classes of antibiotics used in the small ruminant industry in the Netherlands in 2011 and 2012. Twelve large veterinary practices, located throughout the Netherlands were selected for this study. All small ruminant farms associated with these practices that had complete records on the quantity of antibiotics prescribed were included. The veterinary practices provided data on all antibiotics prescribed, and the estimated animal used daily dose of antibiotics per year (AUDD/Y was calculated for each farm. The median AUDD/Y in small ruminant farms was zero in both years (mean 0.60 in 2011, and 0.62 in 2012. The largest quantity of antibiotic use was observed in the professional goat industry (herds of ≥32 goats with a median AUDD/Y of 1.22 in 2011 and 0.73 in 2012. In the professional sheep industry (flocks of ≥32 sheep, the median AUDD/Y was 0 in 2011 and 0.10 in 2012. In the small scale industry (flocks or herds of <32 sheep or goats, the median AUDD/Y never exceeded 0. The most frequently prescribed antibiotics in the small scale industry and professional sheep farms belonged to the penicillin class. In professional goat farms, antibiotics of the aminoglycoside class were most frequently prescribed. This study provides the first assessment on the quantity of antibiotic use in the small ruminant industry. Given a comparable attitude towards antibiotic use, these results might be valid for small ruminant populations in other north-western European countries as well. The antibiotic use in the small ruminant industry appeared to be low, and is expected to play a minor role in the development of antibiotic resistance. Nevertheless, several major zoonotic bacterial pathogens are associated with the small ruminant industry, and it remains important that antibiotics are used in a prudent way.

  17. [Modification of antibiotic resistance in microbial symbiosis].

    Science.gov (United States)

    Aznabaeva, L M; Usviatsov, B Ia; Bukharin, O V

    2010-01-01

    In antibiotic therapy it is necessary to use drugs active against the pathogen in its association with the host normal microflora. The aim of the study was to investigate modification of antibiotic resistance under conditions of the pathogen association with the representatives of the host normal microflora and to develop the microbiological criteria for determining effectiveness of antibacterials. Modification of microbial antibiotic resistance was investigated in 408 associations. Various changes in the antibiotic resistance of the strains were revealed: synergism, antagonism and indifference. On the basis of the results it was concluded that in the choice of the antibiotic active against Staphylococcus aureus and Streptococcus pyogenes the preference should be given to oxacillin, gentamicin and levomycetin, since the resistance of the pathogens to these antibiotics under the association conditions did not increase, which could contribute to their destruction, whereas the resistance of the normoflora increased or did not change, which was important for its retention in the biocenosis. The data on changeability of the antibiotic resistance of the microbial strains under the association conditions made it possible to develop microbiological criteria for determining effectiveness of antibiotics in the treatment of inflammatory diseases of microbial etiology (RF Patent No. 2231554). PMID:21033469

  18. 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

  19. Ribosomal Antibiotics: Contemporary Challenges

    Directory of Open Access Journals (Sweden)

    Tamar Auerbach-Nevo

    2016-06-01

    Full Text Available Most ribosomal antibiotics obstruct distinct ribosomal functions. In selected cases, in addition to paralyzing vital ribosomal tasks, some ribosomal antibiotics are involved in cellular regulation. Owing to the global rapid increase in the appearance of multi-drug resistance in pathogenic bacterial strains, and to the extremely slow progress in developing new antibiotics worldwide, it seems that, in addition to the traditional attempts at improving current antibiotics and the intensive screening for additional natural compounds, this field should undergo substantial conceptual revision. Here, we highlight several contemporary issues, including challenging the common preference of broad-range antibiotics; the marginal attention to alterations in the microbiome population resulting from antibiotics usage, and the insufficient awareness of ecological and environmental aspects of antibiotics usage. We also highlight recent advances in the identification of species-specific structural motifs that may be exploited for the design and the creation of novel, environmental friendly, degradable, antibiotic types, with a better distinction between pathogens and useful bacterial species in the microbiome. Thus, these studies are leading towards the design of “pathogen-specific antibiotics,” in contrast to the current preference of broad range antibiotics, partially because it requires significant efforts in speeding up the discovery of the unique species motifs as well as the clinical pathogen identification.

  20. Ribosomal Antibiotics: Contemporary Challenges.

    Science.gov (United States)

    Auerbach-Nevo, Tamar; Baram, David; Bashan, Anat; Belousoff, Matthew; Breiner, Elinor; Davidovich, Chen; Cimicata, Giuseppe; Eyal, Zohar; Halfon, Yehuda; Krupkin, Miri; Matzov, Donna; Metz, Markus; Rufayda, Mruwat; Peretz, Moshe; Pick, Ophir; Pyetan, Erez; Rozenberg, Haim; Shalev-Benami, Moran; Wekselman, Itai; Zarivach, Raz; Zimmerman, Ella; Assis, Nofar; Bloch, Joel; Israeli, Hadar; Kalaora, Rinat; Lim, Lisha; Sade-Falk, Ofir; Shapira, Tal; Taha-Salaime, Leena; Tang, Hua; Yonath, Ada

    2016-01-01

    Most ribosomal antibiotics obstruct distinct ribosomal functions. In selected cases, in addition to paralyzing vital ribosomal tasks, some ribosomal antibiotics are involved in cellular regulation. Owing to the global rapid increase in the appearance of multi-drug resistance in pathogenic bacterial strains, and to the extremely slow progress in developing new antibiotics worldwide, it seems that, in addition to the traditional attempts at improving current antibiotics and the intensive screening for additional natural compounds, this field should undergo substantial conceptual revision. Here, we highlight several contemporary issues, including challenging the common preference of broad-range antibiotics; the marginal attention to alterations in the microbiome population resulting from antibiotics usage, and the insufficient awareness of ecological and environmental aspects of antibiotics usage. We also highlight recent advances in the identification of species-specific structural motifs that may be exploited for the design and the creation of novel, environmental friendly, degradable, antibiotic types, with a better distinction between pathogens and useful bacterial species in the microbiome. Thus, these studies are leading towards the design of "pathogen-specific antibiotics," in contrast to the current preference of broad range antibiotics, partially because it requires significant efforts in speeding up the discovery of the unique species motifs as well as the clinical pathogen identification. PMID:27367739

  1. Paracelsin; characterization by NMR spectroscopy and circular dichroism, and hemolytic properties of a peptaibol antibiotic from the cellulolytically active mold Trichoderma reesei. Part B.

    Science.gov (United States)

    Brückner, H; Graf, H; Bokel, M

    1984-11-15

    Paracelsin, a hemolytic and membrane active polypeptide antibiotic of the peptaibol class which is excreted by the mold Trichoderma reesei, was obtained by a simplified and rapid isolation procedure utilizing hydrophobic adsorber resins. Investigation by 13C nuclear magnetic resonance spectroscopy and circular dichroism revealed considerable helical portions in solution, and the very recently accomplished sequence determination of paracelsin allows the discussion of the results with regard to the closely related analogues, alamethicin and suzukacillin. A selective cleavage of the peptide was achieved by careful treatment with various acids, and a buffer of pH 8.25 and of high ionic strength made possible the quantitative determination of the C-terminal phenylalaninol released by means of ion-exchange chromatography. The significance of the production of paracelsin and related mycotoxins of the peptaibol class, exhibiting various kinds of biological activity, is discussed with respect to the extensive effort being made towards biotechnological applications of species, strains and cellulolytically highly active mutants of the fungus Trichoderma. PMID:6500005

  2. X-ray crystallographic, FT-IR and NMR studies as well as anticancer and antibacterial activity of the salt formed between ionophore antibiotic Lasalocid acid and amines

    Science.gov (United States)

    Huczyński, Adam; Rutkowski, Jacek; Wietrzyk, Joanna; Stefańska, Joanna; Maj, Ewa; Ratajczak-Sitarz, Małgorzata; Katrusiak, Andrzej; Brzezinski, Bogumil; Bartl, Franz

    2013-01-01

    Two new complexes of the ionophore antibiotic Lasalocid acid (LAS) with phenylamine (PhA) and butylamine (BuA) were synthesized and their molecular structures were studied using single crystal X-ray diffraction and spectroscopic methods. In the solid state both amines are protonated and all NH3+ protons are hydrogen bonded to etheric, hydroxyl and carboxylic oxygen atoms of the LAS anion. In chloroform solutions the structure observed in the crystal of LAS-BuA complex is preserved and an equilibrium between the LAS-PhA complex and dissociated Lasalocid acid and phenylamine is observed. In vitro antimicrobial tests of the complexes showed a significant activity towards some strains of Gram-positive bacteria. For the first time Lasalocid acid and its complexes with amines were tested in vitro for cytotoxic activity against human cancer cell lines: A-549 (lung), MCF-7 (breast), HT-29 (colon) and mouse cancer cell line P-388 (leukemia). We found that LAS and its complexes are strong cytotoxic agents towards all tested cell lines. The cytostatic activity of the compounds studied is greater than that of cisplatin, indicating that Lasalocid and its complexes are promising candidates for new anticancer drugs.

  3. Emerging antibiotic resistance in bacteria with special reference to India

    Indian Academy of Sciences (India)

    D Raghunath

    2008-11-01

    The antibiotic era started in the 1940s and changed the profile of infectious diseases and human demography. The burgeoning classes and numbers promised much and elimination of this major cause of human (and animal) morbidity appeared possible. Bacterial antibiotic resistance which was observed soon after antibiotic introduction has been studied extensively. Diverse mechanisms have been demonstrated and the genetic basis elucidated. The resilience of the prokaryote ecosystems to antibiotic stress has been realized. The paper presents these subjects briefly to afford an overview. The epidemiology of antibiotic resistance is dealt with and community practices in different countries are described. The role of high antibiotic usage environments is indicated. The implication of the wide use of antibiotics in animals has been pointed out. Steadily increasing antibiotic resistance and decreasing numbers of newer antibiotics appear to point to a post-antibiotic period during which treatment of infections would become increasingly difficult. This article attempts to review the global antimicrobial resistance scene and juxtaposes it to the Indian experience. The prevalence in India of antibiotic resistance among major groups of pathogens is described. The factors that determine the prevalent high antibiotic resistance rates have been highlighted. The future research activity to ensure continued utility of antibiotics in the control of infections has been indicated.

  4. Macrophage adaptation leads to parallel evolution of genetically diverse Escherichia coli small-colony variants with increased fitness in vivo and antibiotic collateral sensitivity.

    Science.gov (United States)

    Ramiro, Ricardo S; Costa, Henrique; Gordo, Isabel

    2016-09-01

    Small-colony variants (SCVs) are commonly observed in evolution experiments and clinical isolates, being associated with antibiotic resistance and persistent infections. We recently observed the repeated emergence of Escherichia coli SCVs during adaptation to the interaction with macrophages. To identify the genetic targets underlying the emergence of this clinically relevant morphotype, we performed whole-genome sequencing of independently evolved SCV clones. We uncovered novel mutational targets, not previously associated with SCVs (e.g. cydA, pepP) and observed widespread functional parallelism. All SCV clones had mutations in genes related to the electron-transport chain. As SCVs emerged during adaptation to macrophages, and often show increased antibiotic resistance, we measured SCV fitness inside macrophages and measured their antibiotic resistance profiles. SCVs had a fitness advantage inside macrophages and showed increased aminoglycoside resistance in vitro, but had collateral sensitivity to other antibiotics (e.g. tetracycline). Importantly, we observed similar results in vivo. SCVs had a fitness advantage upon colonization of the mouse gut, which could be tuned by antibiotic treatment: kanamycin (aminoglycoside) increased SCV fitness, but tetracycline strongly reduced it. Our results highlight the power of using experimental evolution as the basis for identifying the causes and consequences of adaptation during host-microbe interactions. PMID:27606007

  5. Genetic architecture of intrinsic antibiotic susceptibility.

    Directory of Open Access Journals (Sweden)

    Hany S Girgis

    Full Text Available BACKGROUND: Antibiotic exposure rapidly selects for more resistant bacterial strains, and both a drug's chemical structure and a bacterium's cellular network affect the types of mutations acquired. METHODOLOGY/PRINCIPAL FINDINGS: To better characterize the genetic determinants of antibiotic susceptibility, we exposed a transposon-mutagenized library of Escherichia coli to each of 17 antibiotics that encompass a wide range of drug classes and mechanisms of action. Propagating the library for multiple generations with drug concentrations that moderately inhibited the growth of the isogenic parental strain caused the abundance of strains with even minor fitness advantages or disadvantages to change measurably and reproducibly. Using a microarray-based genetic footprinting strategy, we then determined the quantitative contribution of each gene to E. coli's intrinsic antibiotic susceptibility. We found both loci whose removal increased general antibiotic tolerance as well as pathways whose down-regulation increased tolerance to specific drugs and drug classes. The beneficial mutations identified span multiple pathways, and we identified pairs of mutations that individually provide only minor decreases in antibiotic susceptibility but that combine to provide higher tolerance. CONCLUSIONS/SIGNIFICANCE: Our results illustrate that a wide-range of mutations can modulate the activity of many cellular resistance processes and demonstrate that E. coli has a large mutational target size for increasing antibiotic tolerance. Furthermore, the work suggests that clinical levels of antibiotic resistance might develop through the sequential accumulation of chromosomal mutations of small individual effect.

  6. In Vitro Activities of Antibiotics Alone and in Combination against Brucella melitensis at Neutral and Acidic pHs

    OpenAIRE

    Akova, Murat; Gür, Deniz; Livermore, David M; Kocagöz, Tanil; Akalin, H. Erdal

    1999-01-01

    Brucellae survive acidic pHs in phagolysosomes. Azithromycin, streptomycin, and quinolones were active against Brucella melitensis at pH 7.0 but not at pH 5.0; rifampin and doxycycline retained activity at pH 5.0. Regardless of pH, azithromycin-rifampin and ofloxacin-rifampin showed less synergy than established streptomycin-doxycycline and rifampin-doxycycline combinations.

  7. Influence of monocytes and antibiotic treatment on tissue factor activity of endocardial vegetations in rabbits infected with Streptococcus sanguis.

    OpenAIRE

    Bancsi, M J; Veltrop, M H; Bertina, R M; Thompson, J

    1996-01-01

    A main feature in the pathogenesis of bacterial endocarditis is the activation of the coagulation system via the extrinsic pathway, resulting in the formation of infected endocardial vegetations. Earlier studies gave indirect evidence that monocytes play an important role in the procoagulant response during the course of the disease. In this study, we assessed the role of monocytes more directly. We compared weights and tissue factor activities (TFA) of endocardial vegetations of normal rabbi...

  8. SecG is required for antibiotic activities of Pseudomonas sp. YL23 against Erwinia amylovora and Dickeya chrysanthemi.

    Science.gov (United States)

    Liu, Youzhou; Baird, Sonya M; Qiao, Junqing; Du, Yan; Lu, Shi-En

    2015-05-01

    Strain YL23 was isolated from soybean root tips and identified to be Pseudomonas sp. This strain showed broad-spectrum antibacterial activity against bacterial pathogens that are economically important in agriculture. To characterize the genes dedicated to antibacterial activities against microbial phytopathogens, a Tn5-mutation library of YL23 was constructed. Plate bioassays revealed that the mutant YL23-93 lost its antibacterial activities against Erwinia amylovora and Dickeya chrysanthemi as compared with its wild type strain. Genetic and sequencing analyses localized the transposon in a homolog of the secG gene in the mutant YL23-93. Constitutive expression plasmid pUCP26-secG was constructed and electroporated into the mutant YL23-93. Introduction of the plasmid pUCP26-secG restored antibacterial activities of the mutant YL23-93 to E. amylovora and D. chrysanthemi. As expected, empty plasmid pUCP26 could not complement the phenotype of the antibacterial activity in the mutant. Thus the secG gene, belonging to the Sec protein translocation system, is required for antibacterial activity of strain YL23 against E. amylovora and D. chrysanthemi.

  9. Antibiotics: Miracle Drugs

    Centers for Disease Control (CDC) Podcasts

    2015-04-16

    The overuse of antibiotics has led to the development of resistance among bacteria, making antibiotics ineffective in treating certain conditions. This podcast discusses the importance of talking to your healthcare professional about whether or not antibiotics will be beneficial if you’ve been diagnosed with an infectious disease.  Created: 4/16/2015 by Division of Bacterial Diseases (DBD), National Center for Immunization and Respiratory Disease (NCIRD), Get Smart: Know When Antibiotics Work Program.   Date Released: 4/16/2015.

  10. Study on risk factors for nosocomial infections caused by high-level aminoglycoside-resistant Enterococcus and aminoglycoside resistance-related genes%耐氨基苷类高水平肠球菌医院感染的危险因素及氨基糖苷类耐药相关基因研究

    Institute of Scientific and Technical Information of China (English)

    范建中; 周田美; 董晓勤; 王贤军

    2012-01-01

    目的 了解耐氨基糖苷类高水平肠球菌(HLAR)的耐药性和医院感染的危险因素,研究HLAR氨基糖苷类耐药相关基因类型分布.方法 采用全自动微生物鉴定仪VITEK-AMS对857株肠球菌属进行鉴定及抗菌药物敏感性检测;PCR法检测HLAR氨基糖苷类耐药相关基因,并对PCR结果进行测序分析.结果 肠球菌属中HLAR占50.4%,利奈唑胺、万古霉素和替考拉宁对HLAR的抗菌作用最好,但有3株屎肠球菌对万古霉素和替考拉宁耐药,粪肠球菌对氯霉素和四环素的耐药率高于屎肠球菌,而屎肠球菌对其他常用抗菌药物的耐药率明显高于粪肠球菌,粪肠球菌和屎肠球菌的耐药谱明显不同,aac(6')-Ie-aph(2〃)-Ia基因为耐庆大霉素高水平肠球菌(HLGR)的主要耐药基因,占HLGR的88.0%,严重的基础疾病、侵入性操作和头孢三代抗菌药物和激素的应用是肠球菌属医院感染的常见危险因素.结论 HLAR已成为医院感染的重要耐药菌,HLGR产生的主要机制是aac(6')-Ie-aph(2〃)-Ia基因介导对庆大霉素高水平耐药,控制常见医院感染危险因素,合理使用抗菌药物,可减少HLAR医院感染的发生.%OBJECTIVE To explore the antibiotic resistance and risk factors for nosocomial infections caused by high-level aminoglycoside-resistant (HLAR) Enterococcus, and investigate the genotypes related to high-level aminoglycoside resistance. METHODS A total of 857 strains of Enterococcus were identified and analyzed for their antimicrobial susceptibility by VITEK-AMS. The aminoglycoside resistance-related genes were detected by PCR. The sequencing analysis of PCR products was performed. RESULTS A total of 50. 4% of Enterococcus isolates were HLAR Enterococcus. Linezolid, vancomycin and teicoplanin were mostly effective against HLAR Enterococcus, but there were three isolates resistant to vancomycin and teicoplanin. The resistance rates to chloramphenicol and tetracycline of E. Faecium were

  11. Comparative study of the effect of pharmaceutical additives on the elimination of antibiotic activity during the treatment of oxacillin in water by the photo-Fenton, TiO2-photocatalysis and electrochemical processes.

    Science.gov (United States)

    Serna-Galvis, Efraim A; Silva-Agredo, Javier; Giraldo, Ana L; Flórez-Acosta, Oscar A; Torres-Palma, Ricardo A

    2016-01-15

    Synthetic pharmaceutical effluents loaded with the β-lactam antibiotic oxacillin were treated using advanced oxidation processes (the photo-Fenton system and TiO2 photocatalysis) and chloride mediated electrochemical oxidation (with Ti/IrO2 anodes). Combinations of the antibiotic with excipients (mannitol or tartaric acid), an active ingredient (calcium carbonate, i.e. bicarbonate ions due to the pH) and a cleaning agent (sodium lauryl ether sulfate) were considered. Additionally, urban wastewater that had undergone biological treatment was doped with oxacillin and treated with the tested systems. The evolution of antimicrobial activity was monitored as a parameter of processes efficiency. Although the two advanced oxidation processes (AOPs) differ only in the way they produce OH, marked differences were observed between them. There were also differences between the AOPs and the electrochemical system. Interestingly, each additive had a different effect on each treatment. For water loaded with mannitol, electrochemical treatment was the most suitable option because the additive did not significantly affect the efficiency of the system. Due to the formation of a complex with Fe(3+), tartaric acid accelerated the elimination of antibiotic activity during the photo-Fenton process. For TiO2 photocatalysis, the presence of bicarbonate ions contributed to antibiotic activity elimination through the possible formation of carbonate and bicarbonate radicals. Sodium lauryl ether sulfate negatively affected all of the processes. However, due to the higher selectivity of HOCl compared with OH, electrochemical oxidation showed the least inhibited efficiency. For the urban wastewater doped with oxacillin, TiO2 photocatalysis was the most efficient process. These results will help select the most suitable technology for the treatment of water polluted with β-lactam antibiotics.

  12. Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity.

    Science.gov (United States)

    Moreira, Nuno F F; Sousa, José M; Macedo, Gonçalo; Ribeiro, Ana R; Barreiros, Luisa; Pedrosa, Marta; Faria, Joaquim L; Pereira, M Fernando R; Castro-Silva, Sérgio; Segundo, Marcela A; Manaia, Célia M; Nunes, Olga C; Silva, Adrián M T

    2016-05-01

    Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01-0.20 ng L(-1)). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed

  13. Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity.

    Science.gov (United States)

    Moreira, Nuno F F; Sousa, José M; Macedo, Gonçalo; Ribeiro, Ana R; Barreiros, Luisa; Pedrosa, Marta; Faria, Joaquim L; Pereira, M Fernando R; Castro-Silva, Sérgio; Segundo, Marcela A; Manaia, Célia M; Nunes, Olga C; Silva, Adrián M T

    2016-05-01

    Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01-0.20 ng L(-1)). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed

  14. A Site-Specific Integrative Plasmid Found in Pseudomonas aeruginosa Clinical Isolate HS87 along with A Plasmid Carrying an Aminoglycoside-Resistant Gene.

    Directory of Open Access Journals (Sweden)

    Dexi Bi

    Full Text Available Plasmids play critical roles in bacterial fitness and evolution of Pseudomonas aeruginosa. Here two plasmids found in a drug-resistant P. aeruginosa clinical isolate HS87 were completely sequenced. The pHS87b plasmid (11.2 kb carries phage-related genes and function-unknown genes. Notably, pHS87b encodes an integrase and has an adjacent tRNAThr-associated attachment site. A corresponding integrated form of pHS87b at the tRNAThr locus was identified on the chromosome of P. aeruginosa, showing that pHS87b is able to site-specifically integrate into the 3'-end of the tRNAThr gene. The pHS87a plasmid (26.8 kb displays a plastic structure containing a putative replication module, stability factors and a variable region. The RepA of pHS87a shows significant similarity to the replication proteins of pPT23A-family plasmids. pHS87a carries a transposon Tn6049, a truncated insertion sequence ΔIS1071 and a Tn402-like class 1 integron which contains an aacA4 cassette that may confer aminoglycoside resistance. Thus, pHS87b is a site-specific integrative plasmid whereas pHS87a is a plastic antibiotic resistance plasmid. The two native plasmids may promote the fitness and evolution of P. aeruginosa.

  15. A Site-Specific Integrative Plasmid Found in Pseudomonas aeruginosa Clinical Isolate HS87 along with A Plasmid Carrying an Aminoglycoside-Resistant Gene.

    Science.gov (United States)

    Bi, Dexi; Xie, Yingzhou; Tai, Cui; Jiang, Xiaofei; Zhang, Jie; Harrison, Ewan M; Jia, Shiru; Deng, Zixin; Rajakumar, Kumar; Ou, Hong-Yu

    2016-01-01

    Plasmids play critical roles in bacterial fitness and evolution of Pseudomonas aeruginosa. Here two plasmids found in a drug-resistant P. aeruginosa clinical isolate HS87 were completely sequenced. The pHS87b plasmid (11.2 kb) carries phage-related genes and function-unknown genes. Notably, pHS87b encodes an integrase and has an adjacent tRNAThr-associated attachment site. A corresponding integrated form of pHS87b at the tRNAThr locus was identified on the chromosome of P. aeruginosa, showing that pHS87b is able to site-specifically integrate into the 3'-end of the tRNAThr gene. The pHS87a plasmid (26.8 kb) displays a plastic structure containing a putative replication module, stability factors and a variable region. The RepA of pHS87a shows significant similarity to the replication proteins of pPT23A-family plasmids. pHS87a carries a transposon Tn6049, a truncated insertion sequence ΔIS1071 and a Tn402-like class 1 integron which contains an aacA4 cassette that may confer aminoglycoside resistance. Thus, pHS87b is a site-specific integrative plasmid whereas pHS87a is a plastic antibiotic resistance plasmid. The two native plasmids may promote the fitness and evolution of P. aeruginosa. PMID:26841043

  16. In vitro activities of aztreonam, piperacillin, and ticarcillin combined with amikacin against amikacin-resistant Pseudomonas aeruginosa and P. cepacia isolates from children with cystic fibrosis.

    OpenAIRE

    Aronoff, S C; Klinger, J D

    1984-01-01

    Amikacin, combined with aztreonam, piperacillin, or ticarcillin, synergistically inhibited amikacin-resistant sputum isolates of Pseudomonas aeruginosa and P. cepacia from children with cystic fibrosis. Ticarcillin-amikacin was the least active combination. Aminoglycoside resistance should not preclude the use of beta-lactam-aminoglycoside combinations in the treatment of pulmonary infections in cystic fibrosis.

  17. Influence of inducible cross-resistance to macrolides, lincosamides, and streptogramin B-type antibiotics in Enterococcus faecium on activity of quinupristin-dalfopristin in vitro and in rabbits with experimental endocarditis.

    OpenAIRE

    Fantin, B.; Leclercq, R.; Garry, L; Carbon, C

    1997-01-01

    The influence of inducible cross-resistance to macrolides, lincosamides, and streptogramin B (MLS(B)) type antibiotics (inducible MLS(B) phenotype) on the activity of quinupristin-dalfopristin was investigated against Enterococcus faecium in vitro and in rabbits with experimental endocarditis. In vitro, quinupristin-dalfopristin displayed bacteriostatic and bactericidal activities against a MLS(B)-susceptible strain similar to those against two strains with the inducible MLS(B) phenotype. In ...

  18. Antibacterial activities of selected Cameroonian spices and their synergistic effects with antibiotics against multidrug-resistant phenotypes

    Directory of Open Access Journals (Sweden)

    Fankam Aimé G

    2011-11-01

    Full Text Available Abstract Background The emergence of multi-drug resistant (MDR phenotypes is a major public health problem today in the treatment of bacterial infections. The present study was designed to evaluate the antibacterial activities of the methanol extracts of eleven Cameroonian spices on a panel of twenty nine Gram negative bacteria including MDR strains. Methods The phytochemical analysis of the extracts was carried out by standard tests meanwhile the liquid micro-broth dilution was used for all antimicrobial assays. Results Phytochemical analysis showed the presence of alkaloids, phenols and tannins in all plants extracts. The results of the antibacterial assays indicated that all tested extracts exert antibacterial activities, with the minimum inhibitory concentration (MIC values varying from 32 to 1024 μg/ml. The extracts from Dichrostachys glomerata, Beilschmiedia cinnamomea, Aframomum citratum, Piper capense, Echinops giganteus, Fagara xanthoxyloïdes and Olax subscorpioïdea were the most active. In the presence of efflux pump inhibitor, PAßN, the activity of the extract from D. glomerata significantly increased on 69.2% of the tested MDR bacteria. At MIC/5, synergistic effects were noted with the extract of D. glomerata on 75% of the tested bacteria for chloramphenicol (CHL, tetracycline (TET and norfloxacin (NOR. With B. cinnamomea synergy were observed on 62.5% of the studied MDR bacteria with CHL, cefepime (FEP, NOR and ciprofloxacin (CIP and 75% with erythromycin (ERY. Conclusion The overall results provide information for the possible use of the studied extracts of the spices in the control of bacterial infections involving MDR phenotypes.

  19. Coping with antibiotic resistance: combining nanoparticles with antibiotics and other antimicrobial agents.

    Science.gov (United States)

    Allahverdiyev, Adil M; Kon, Kateryna Volodymyrivna; Abamor, Emrah Sefik; Bagirova, Malahat; Rafailovich, Miriam

    2011-11-01

    The worldwide escalation of bacterial resistance to conventional medical antibiotics is a serious concern for modern medicine. High prevalence of multidrug-resistant bacteria among bacteria-based infections decreases effectiveness of current treatments and causes thousands of deaths. New improvements in present methods and novel strategies are urgently needed to cope with this problem. Owing to their antibacterial activities, metallic nanoparticles represent an effective solution for overcoming bacterial resistance. However, metallic nanoparticles are toxic, which causes restrictions in their use. Recent studies have shown that combining nanoparticles with antibiotics not only reduces the toxicity of both agents towards human cells by decreasing the requirement for high dosages but also enhances their bactericidal properties. Combining antibiotics with nanoparticles also restores their ability to destroy bacteria that have acquired resistance to them. Furthermore, nanoparticles tagged with antibiotics have been shown to increase the concentration of antibiotics at the site of bacterium-antibiotic interaction, and to facilitate binding of antibiotics to bacteria. Likewise, combining nanoparticles with antimicrobial peptides and essential oils generates genuine synergy against bacterial resistance. In this article, we aim to summarize recent studies on interactions between nanoparticles and antibiotics, as well as other antibacterial agents to formulate new prospects for future studies. Based on the promising data that demonstrated the synergistic effects of antimicrobial agents with nanoparticles, we believe that this combination is a potential candidate for more research into treatments for antibiotic-resistant bacteria. PMID:22029522

  20. Marker-free plasmids for gene therapeutic applications--lack of antibiotic resistance gene substantially improves the manufacturing process.

    Science.gov (United States)

    Mairhofer, Jürgen; Cserjan-Puschmann, Monika; Striedner, Gerald; Nöbauer, Katharina; Razzazi-Fazeli, Ebrahim; Grabherr, Reingard

    2010-04-01

    Plasmid DNA is being considered as a promising alternative to traditional protein vaccines or viral delivery methods for gene therapeutic applications. DNA-based products are highly flexible, stable, are easily stored and can be manufactured on a large scale. Although, much safer than viral approaches, issues have been raised with regard to safety due to possible integration of plasmid DNA into cellular DNA or spread of antibiotic resistance genes to intestinal bacteria by horizontal gene transfer. Accordingly, there is interest in methods for the production of plasmid DNA that lacks the antibiotic resistance gene to further improve their safety profile. Here, we report for the first time the gram-scale manufacturing of a minimized plasmid that is devoid of any additional sequence elements on the plasmid backbone, and merely consists of the target expression cassette and the bacterial origin of replication. Three different host/vector combinations were cultivated in a fed-batch fermentation process, comparing the progenitor strain JM108 to modified strains JM108murselect, hosting a plasmid either containing the aminoglycoside phosphotransferase which provides kanamycin resistance, or a marker-free variant of the same plasmid. The metabolic load exerted by expression of the aminoglycoside phosphotransferase was monitored by measuring ppGpp- and cAMP-levels. Moreover, we revealed that JM108 is deficient of the Lon protease and thereby refined the genotype of JM108. The main consequences of Lon-deficiency with regard to plasmid DNA production are discussed herein. Additionally, we found that the expression of the aminoglycoside phosphotransferase, conferring resistance to kanamycin, was very high in plasmid DNA producing processes that actually inclusion bodies were formed. Thereby, a severe metabolic load on the host cell was imposed, detrimental for overall plasmid yield. Hence, deleting the antibiotic resistance gene from the vector backbone is not only beneficial

  1. The future of antibiotics.

    Science.gov (United States)

    Spellberg, Brad

    2014-01-01

    Antibiotic resistance continues to spread even as society is experiencing a market failure of new antibiotic research and development (R&D). Scientific, economic, and regulatory barriers all contribute to the antibiotic market failure. Scientific solutions to rekindle R&D include finding new screening strategies to identify novel antibiotic scaffolds and transforming the way we think about treating infections, such that the goal is to disarm the pathogen without killing it or modulate the host response to the organism without targeting the organism for destruction. Future economic strategies are likely to focus on 'push' incentives offered by public-private partnerships as well as increasing pricing by focusing development on areas of high unmet need. Such strategies can also help protect new antibiotics from overuse after marketing. Regulatory reform is needed to re-establish feasible and meaningful traditional antibiotic pathways, to create novel limited-use pathways that focus on highly resistant infections, and to harmonize regulatory standards across nations. We need new antibiotics with which to treat our patients. But we also need to protect those new antibiotics from misuse when they become available. If we want to break the cycle of resistance and change the current landscape, disruptive approaches that challenge long-standing dogma will be needed. PMID:25043962

  2. Broad spectrum antibiotic compounds and use thereof

    Energy Technology Data Exchange (ETDEWEB)

    Koglin, Alexander; Strieker, Matthias

    2016-07-05

    The discovery of a non-ribosomal peptide synthetase (NRPS) gene cluster in the genome of Clostridium thermocellum that produces a secondary metabolite that is assembled outside of the host membrane is described. Also described is the identification of homologous NRPS gene clusters from several additional microorganisms. The secondary metabolites produced by the NRPS gene clusters exhibit broad spectrum antibiotic activity. Thus, antibiotic compounds produced by the NRPS gene clusters, and analogs thereof, their use for inhibiting bacterial growth, and methods of making the antibiotic compounds are described.

  3. A study of the catalytic role of a gold electrode in the electrochemical activation of four macrolide antibiotics in sodium bicarbonate solution

    Directory of Open Access Journals (Sweden)

    Milka L. Avramov Ivić

    2010-07-01

    Full Text Available Using the cyclic voltammetry, it has been shown that hydrogen evolution at a gold electrode is necessary in the electrochemical activation of azithromycin dihydrate and erythromycin A. After four hours of the potential holding at –1.2 V vs. SCE, the pH of the electrolyte has been changed from 8.40 to 8.96; from 8.40 to 8.77 in the presence of erythromycin A, and from 8.40 to 9.18 in the presence of azithromycin, indicating the reaction of the hydrogen species with antibiotics. This effect has been confirmed by using the phenolphthalein indicator and by analysing colours of the solutions by UV-Vis, as well as by FTIR spectroscopy. Under the identical experimental conditions at the gold electrode, in contrast to azithromycin dihydrate and erythromycin A, roxithromycin and midecamycin electroactivity promotion has been obtained during the first forward sweep starting from the area of a double layer region.

  4. Nationwide German Multicenter Study on Prevalence of Antibiotic Resistance in Staphylococcal Bloodstream Isolates and Comparative In Vitro Activities of Quinupristin-Dalfopristin

    OpenAIRE

    von Eiff, Christof; Reinert, Ralf René; Kresken, Michael; Brauers, Johannes; Hafner, Dieter; Peters, Georg

    2000-01-01

    Antibiotic-resistant gram-positive bacteria have become an increasing problem in the last two decades. In order to evaluate the prevalence of antibiotic resistance in staphylococcal bloodstream isolates in Germany, 2,042 staphylococci collected in 21 tertiary-care hospitals were investigated during a 3-year period (March 1996 to March 1999). Altogether, 1,448 S. aureus isolates and 594 coagulase-negative staphylococci (CoNS) that comprised 13 different species were included. Furthermore, the ...

  5. Metagenomics and antibiotics.

    Science.gov (United States)

    Garmendia, L; Hernandez, A; Sanchez, M B; Martinez, J L

    2012-07-01

    Most of the bacterial species that form part of the biosphere have never been cultivated. In this situation, a comprehensive study of bacterial communities requires the utilization of non-culture-based methods, which have been named metagenomics. In this paper we review the use of different metagenomic techniques for understanding the effect of antibiotics on microbial communities, to synthesize new antimicrobial compounds and to analyse the distribution of antibiotic resistance genes in different ecosystems. These techniques include functional metagenomics, which serves to find new antibiotics or new antibiotic resistance genes, and descriptive metagenomics, which serves to analyse changes in the composition of the microbiota and to track the presence and abundance of already known antibiotic resistance genes in different ecosystems.

  6. Biosynthesis of Enediyne Antitumor Antibiotics

    OpenAIRE

    Van Lanen, Steven G.; Shen, Ben

    2008-01-01

    The enediyne polyketides are secondary metabolites isolated from a variety of Actinomycetes. All members share very potent anticancer and antibiotic activity, and prospects for the clinical application of the enediynes has been validated with the recent marketing of two enediyne derivatives as anticancer agents. The biosynthesis of these compounds is of interest because of the numerous structural features that are unique to the enediyne family. The gene cluster for five enediynes has now been...

  7. Uncialamycin, a new enediyne antibiotic.

    Science.gov (United States)

    Davies, Julian; Wang, Hao; Taylor, Terry; Warabi, Kaoru; Huang, Xin-Hui; Andersen, Raymond J

    2005-11-10

    [structure: see text] Laboratory cultures of an undescribed streptomycete obtained from the surface of a British Columbia lichen produce uncialamycin (1), a new enediyne antibiotic. The structure of uncialamycin (1) has been elucidated by analysis of spectroscopic data. Uncialamycin (1) exhibits potent in vitro antibacterial activity against gram-positive and gram-negative human pathogens, including Burkholderia cepacia, a major cause of morbidity and mortality in patients with cystic fibrosis. PMID:16268546

  8. Minocycline: far beyond an antibiotic

    OpenAIRE

    Garrido-Mesa, N; Zarzuelo, A; Gálvez, J

    2013-01-01

    Minocycline is a second-generation, semi-synthetic tetracycline that has been in therapeutic use for over 30 years because of its antibiotic properties against both gram-positive and gram-negative bacteria. It is mainly used in the treatment of acne vulgaris and some sexually transmitted diseases. Recently, it has been reported that tetracyclines can exert a variety of biological actions that are independent of their anti-microbial activity, including anti-inflammatory and anti-apoptotic acti...

  9. A study of the electrochemical activity of some macrolide antibiotics on a gold electrode in a neutral electrolyte

    Directory of Open Access Journals (Sweden)

    M. L. AVRAMOV IVIC

    2007-12-01

    Full Text Available The aim of the present study is to present the different reactivity of azithromycin and clarithromycin (pure and commercial at a gold electrode in neutral electrolyte using cyclic linear sweep voltammetry under the same experimental conditions. A gold electrode was successfully used for the electrochemical qualitative and quantitative determination of azithromycin dihydrate and azithromycin from capsules (Hemomycin® and for the separation of azithromycin from one of the excipients, lactose monohydrate. The good catalytically activity of the gold electrode was employed only for the qualitative electrochemical determination of pure clarithromycin by appearance of one cathodic and four anodic reactions, which enabled structural changes in this molecule during electrochemical reactions to be studied. Commercial clarithromycin, Clathrocyn® was qualitative determined by one reproducible anodic reaction. The activity of one of the excipients, Avicel, observed as a cathodic peak at different potential from the cathodic peak obtained with pure clarithromicin was used for the determination of its presence in Clathrocyn® tablets. FTIR Analysis showed the apparent changes in structure of pure clarithromycin, as well as in the molecule of clarithromycin in Clathrocyn® tablets. HPLC Analysis showed a significant decrease in the concentration of azithromycin, Hemomycin® clarithromycin and Clathrocyn® after the electrochemical reactions.

  10. Osteopontin That Is Elevated in the Airways during COPD Impairs the Antibacterial Activity of Common Innate Antibiotics.

    Directory of Open Access Journals (Sweden)

    Anele Gela

    Full Text Available Bacterial infections of the respiratory tract contribute to exacerbations and disease progression in chronic obstructive pulmonary disease (COPD. There is also an increased risk of invasive pneumococcal disease in COPD. The underlying mechanisms are not fully understood but include impaired mucociliary clearance and structural remodeling of the airways. In addition, antimicrobial proteins that are constitutively expressed or induced during inflammatory conditions are an important part of the airway innate host defense. In the present study, we show that osteopontin (OPN, a multifunctional glycoprotein that is highly upregulated in the airways of COPD patients co-localizes with several antimicrobial proteins expressed in the airways. In vitro, OPN bound lactoferrin, secretory leukocyte peptidase inhibitor (SLPI, midkine, human beta defensin-3 (hBD-3, and thymic stromal lymphopoietin (TSLP but showed low or no affinity for lysozyme and LL-37. Binding of OPN impaired the antibacterial activity against the important bacterial pathogens Streptococcus pneumoniae and Pseudomonas aeruginosa. Interestingly, OPN reduced lysozyme-induced killing of S. pneumoniae, a finding that could be explained by binding of OPN to the bacterial surface, thereby shielding the bacteria. A fragment of OPN generated by elastase of P. aeruginosa retained some inhibitory effect. Some antimicrobial proteins have additional functions. However, the muramidase-activity of lysozyme and the protease inhibitory function of SLPI were not affected by OPN. Taken together, OPN can contribute to the impairment of innate host defense by interfering with the function of antimicrobial proteins, thus increasing the vulnerability to acquire infections during COPD.

  11. Correction of ATM gene function by aminoglycoside-induced read-through of premature termination codons

    OpenAIRE

    Lai, Chih-Hung; Chun, Helen H.; Nahas, Shareef A.; Mitui, Midori; Gamo, Kristin M.; Du, Liutao; Gatti, Richard A.

    2004-01-01

    Approximately 14% of genetic mutations in patients with ataxia-telangiectsia (A-T) are single-nucleotide changes that result in primary premature termination codons (PTCs), either UAA, UAG, or UGA. The purpose of this study was to explore a potential therapeutic approach for this subset of patients by using aminoglycosides to induce PTC read-through, thereby restoring levels of full-length ATM (A-T mutated) protein. In experiments using a modified in vitro cDNA coupled transcription/translati...

  12. Synthesis of 4′-aminopantetheine and derivatives to probe aminoglycoside N-6′-acetyltransferase

    Science.gov (United States)

    Yan, Xuxu; Akinnusi, T. Olukayode; Larsen, Aaron T.; Auclair, Karine

    2011-01-01

    Summary A convenient synthesis of 4′-aminopantetheine from commercial D-pantethine is reported. The amino group was introduced by reductive amination in order to avoid substitution at a sterically congested position. Derivatives of 4′-aminopantetheine were also prepared to evaluate the effect of O-to-N substitution on inhibitors of the resistance-causing enzyme aminoglycoside N-6′-acetyltransferase. The biological results combined with docking studies indicate that in spite of its reported unusual flexibility and ability to adopt different folds, this enzyme is highly specific for AcCoA. PMID:21225062

  13. Synthesis of 4'-aminopantetheine and derivatives to probe aminoglycoside N-6'-acetyltransferase.

    Science.gov (United States)

    Yan, Xuxu; Akinnusi, T Olukayode; Larsen, Aaron T; Auclair, Karine

    2011-03-01

    A convenient synthesis of 4'-aminopantetheine from commercial D-pantethine is reported. The amino group was introduced by reductive amination in order to avoid substitution at a sterically congested position. Derivatives of 4'-aminopantetheine were also prepared to evaluate the effect of O-to-N substitution on inhibitors of the resistance-causing enzyme aminoglycoside N-6'-acetyltransferase. The biological results combined with docking studies indicate that in spite of its reported unusual flexibility and ability to adopt different folds, this enzyme is highly specific for AcCoA. PMID:21225062

  14. Worldwide Disseminated armA Aminoglycoside Resistance Methylase Gene Is Borne by Composite Transposon Tn1548

    OpenAIRE

    Galimand, M.; Sabtcheva, S.; Courvalin, P; Lambert, T.

    2005-01-01

    The armA (aminoglycoside resistance methylase) gene, which confers resistance to 4,6-disubstituted deoxystreptamines and fortimicin, was initially found in Klebsiella pneumoniae BM4536 on IncL/M plasmid pIP1204 of ca. 90 kb which also encodes the extended-spectrum β-lactamase CTX-M-3. Thirty-four enterobacteria from various countries that were likely to produce a CTX-M enzyme since they were more resistant to cefotaxime than to ceftazidime were studied. The armA gene was detected in 12 clinic...

  15. Mining microbial metatranscriptomes for expression of antibiotic resistance genes under natural conditions

    Science.gov (United States)

    Versluis, Dennis; D'Andrea, Marco Maria; Ramiro Garcia, Javier; Leimena, Milkha M.; Hugenholtz, Floor; Zhang, Jing; Öztürk, Başak; Nylund, Lotta; Sipkema, Detmer; Schaik, Willem Van; de Vos, Willem M.; Kleerebezem, Michiel; Smidt, Hauke; Passel, Mark W. J. Van

    2015-07-01

    Antibiotic resistance genes are found in a broad range of ecological niches associated with complex microbiota. Here we investigated if resistance genes are not only present, but also transcribed under natural conditions. Furthermore, we examined the potential for antibiotic production by assessing the expression of associated secondary metabolite biosynthesis gene clusters. Metatranscriptome datasets from intestinal microbiota of four human adults, one human infant, 15 mice and six pigs, of which only the latter have received antibiotics prior to the study, as well as from sea bacterioplankton, a marine sponge, forest soil and sub-seafloor sediment, were investigated. We found that resistance genes are expressed in all studied ecological niches, albeit with niche-specific differences in relative expression levels and diversity of transcripts. For example, in mice and human infant microbiota predominantly tetracycline resistance genes were expressed while in human adult microbiota the spectrum of expressed genes was more diverse, and also included β-lactam, aminoglycoside and macrolide resistance genes. Resistance gene expression could result from the presence of natural antibiotics in the environment, although we could not link it to expression of corresponding secondary metabolites biosynthesis clusters. Alternatively, resistance gene expression could be constitutive, or these genes serve alternative roles besides antibiotic resistance.

  16. Utilization Pattern of Antibiotics in Different Wards of Sari Imam Khomeini Teaching Hospital

    Directory of Open Access Journals (Sweden)

    M.A. Ebrahimzadeh, Ph.D.

    2007-01-01

    Full Text Available AbstractBackground and Purpose: Due to an increase in cases of irrational drug prescription and it's health and economic consequences, evaluation of the rational use of drugs seemed necessary. Among drug groups antibiotics are greatly significant.Materials and Methods: Utilization pattern of antibiotics in different wards of Sari Imam Khomeini teaching hospital in the first half of 2000 and 2005 were reviewed. ATC/DDD (Anatomic, Therapeutic, Chemical/ Defined Daily Dose methodology was used.Results: Data showed, use of antibiotics jumped from 95.4 DBDs (DDD per patient’s bed-days to 124 DBDs. Distribution of different class of anti-microbial, showed the highest increase in use of vancomycin and clindamycin. Use of cotrimoxazole and aminoglycosides remained fairly unchanged, howerrs consumption of Penicillin G dropped. In year 2005, ICU ward followed by gynecology, were among the University Hospital departments with the highest consumption of antibiotics. Cefazolin was the most prescribed antibiotics during this study.Conclusion: It appers that there is a need for more national drug policities and drug education program for health care professionals. Evaluation of drug distribution in hospitals seems to be necessary.Key words:

  17. Resistance to antibiotics in Gram-negative bacteria isolated from broiler carcasses

    Directory of Open Access Journals (Sweden)

    Moreira M.A.S.

    2002-01-01

    Full Text Available One hundred and ninety-seven isolates of Gram-negative bacteria, comprising 10 genera, were isolated from poultry carcasses at a processing plant in order to investigate resistance to low levels of antibiotics. The samples were taken just after evisceration and before inspection. Most of the isolates were of Samonella and Escherichia. Other genera present were Enterobacter, Serratia, Klebsiella, Kluyvera, Erwinia, Citrobacter, Pseudomonas and Aeromonas. Distinct profiles of antibiotic resistance were detected. Resistance to more than two antibiotics predominated and spanned several classes of antibiotics. Salmonellae and escherichiae were mainly resistant to the aminoglycosides, followed by tetracycline, nitrofuran, sulpha, macrolide, chloramphenicol, quinolones and beta-lactams. Most isolates were sensitive to 30mug/ml olaquindox, the growth promoter in use at the time of sampling. However, many were resistant to a level of 10mug/ml and 13mug/ml olaquindox, levels present in the gut due to the dilution in the feed. The results suggest a possible role of low level administration of antibiotics to broilers in selecting multi-resistant bacteria in vivo.

  18. Chemical constituents of Parmotrema lichexanthonicum Eliasaro and Alder: isolation, structure modification and evaluation of antibiotic and cytotoxic activities

    International Nuclear Information System (INIS)

    From the lichen Parmotrema lichexantonicum were isolated the depsidone salazinic acid, the xanthone lichexanthone, and the depside atranorin. The two major compounds, salazinic acid and lichexanthone, were selected for structure modifications. Salazinic acid afforded O-alkyl salazinic acids, some of them potentially cytotoxic against tumor cell lines (HCT-8, SF-295 and MDA/ MB - 435). From lichexanthone were obtained norlichexanthone, 3