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Sample records for antimicrobial susceptibility testing

  1. Antimicrobial susceptibility testing for Mycobacterium sp.

    PubMed

    Blanco-Ruano, Delia; Roberts, David M; Gonzalez-Del-Rio, Ruben; Álvarez, Daniel; Rebollo, Ma José; Pérez-Herrán, Esther; Mendoza, Alfonso

    2015-01-01

    The concept of antimicrobial susceptibility testing is an essential part of clinical microbiology. Antimicrobial testing has played a central role in the identification of new antibiotics and defining their clinical uses. Here we describe different approaches to determine the activity of compounds in medium- or high-throughput format. PMID:25779321

  2. Antianaerobic Antimicrobials: Spectrum and Susceptibility Testing

    PubMed Central

    Wexler, Hannah M.; Goldstein, Ellie J. C.

    2013-01-01

    SUMMARY Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described. PMID:23824372

  3. Antianaerobic antimicrobials: spectrum and susceptibility testing.

    PubMed

    Brook, Itzhak; Wexler, Hannah M; Goldstein, Ellie J C

    2013-07-01

    Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described. PMID:23824372

  4. [Internal quality control for antimicrobial susceptibility test: an experience feedback].

    PubMed

    Vedy, Serge

    2012-01-01

    Internal quality control (IQC) position in antimicrobial susceptibility testing must be evaluated attentively before using. Ours S. aureus ATCC 25923 use during year 2011 has given precious information that can be useful for other laboratories. First, IQC should never be used before checking that all the realisation process steps are controlled. It will then appear that reagents are the most susceptible to give false results. That's what happens in 2.74% of antimicrobial susceptibility test. IQC is then useful to limit their clinical's impact. However, IQC use also shows that quality improvement will be difficult without industrial producer's involvement. PMID:22826843

  5. Susceptibility Testing

    MedlinePlus

    ... page helpful? Also known as: Sensitivity Testing; Drug Resistance Testing; Culture and Sensitivity; C & S; Antimicrobial Susceptibility Formal name: Bacterial and Fungal Susceptibility Testing Related tests: Urine Culture ; ...

  6. High-Throughput Intracellular Antimicrobial Susceptibility Testing of Legionella pneumophila

    PubMed Central

    Chiaraviglio, Lucius

    2015-01-01

    Legionella pneumophila is a Gram-negative opportunistic human pathogen that causes a severe pneumonia known as Legionnaires' disease. Notably, in the human host, the organism is believed to replicate solely within an intracellular compartment, predominantly within pulmonary macrophages. Consequently, successful therapy is predicated on antimicrobials penetrating into this intracellular growth niche. However, standard antimicrobial susceptibility testing methods test solely for extracellular growth inhibition. Here, we make use of a high-throughput assay to characterize intracellular growth inhibition activity of known antimicrobials. For select antimicrobials, high-resolution dose-response analysis was then performed to characterize and compare activity levels in both macrophage infection and axenic growth assays. Results support the superiority of several classes of nonpolar antimicrobials in abrogating intracellular growth. Importantly, our assay results show excellent correlations with prior clinical observations of antimicrobial efficacy. Furthermore, we also show the applicability of high-throughput automation to two- and three-dimensional synergy testing. High-resolution isocontour isobolograms provide in vitro support for specific combination antimicrobial therapy. Taken together, findings suggest that high-throughput screening technology may be successfully applied to identify and characterize antimicrobials that target bacterial pathogens that make use of an intracellular growth niche. PMID:26392509

  7. High-Throughput Intracellular Antimicrobial Susceptibility Testing of Legionella pneumophila.

    PubMed

    Chiaraviglio, Lucius; Kirby, James E

    2015-12-01

    Legionella pneumophila is a Gram-negative opportunistic human pathogen that causes a severe pneumonia known as Legionnaires' disease. Notably, in the human host, the organism is believed to replicate solely within an intracellular compartment, predominantly within pulmonary macrophages. Consequently, successful therapy is predicated on antimicrobials penetrating into this intracellular growth niche. However, standard antimicrobial susceptibility testing methods test solely for extracellular growth inhibition. Here, we make use of a high-throughput assay to characterize intracellular growth inhibition activity of known antimicrobials. For select antimicrobials, high-resolution dose-response analysis was then performed to characterize and compare activity levels in both macrophage infection and axenic growth assays. Results support the superiority of several classes of nonpolar antimicrobials in abrogating intracellular growth. Importantly, our assay results show excellent correlations with prior clinical observations of antimicrobial efficacy. Furthermore, we also show the applicability of high-throughput automation to two- and three-dimensional synergy testing. High-resolution isocontour isobolograms provide in vitro support for specific combination antimicrobial therapy. Taken together, findings suggest that high-throughput screening technology may be successfully applied to identify and characterize antimicrobials that target bacterial pathogens that make use of an intracellular growth niche. PMID:26392509

  8. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  9. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  10. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  11. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  12. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  13. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  14. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  15. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  16. 21 CFR 866.1640 - Antimicrobial susceptibility test powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antimicrobial susceptibility test powder. 866.1640 Section 866.1640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1640...

  17. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Antimicrobial susceptibility test disc. 866.1620 Section 866.1620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices § 866.1620...

  18. [Antimicrobial susceptibility testing of anaerobic bacteria].

    PubMed

    García-Sánchez, José E; García-Sánchez, Enrique; García-García, María Inmaculada

    2014-02-01

    The anaerobic bacteria resistance to antibiotics is increasing, and even has appeared against the most active of those, like metronidazol and carbapenems. This fact forces to make and periodical sensibility tests -at least in the most aggressive and virulent species, in cases that they are isolated from life locations and in the absence of therapeutic response- to check the local sensibility and to establish suitable empiric therapies, all based on multicentric studies carried out in order to this or well to check the activity of new antibiotics. For the laboratory routine, the easiest sensibility method is the E-test/MIC evaluator. Another alternative is microdilution, that's only normalized for Bacteroides. There are preliminary facts that allow the use of disc diffusion method in some species of Bacteroides and Clostridium. For the temporal and multicentric studies, the procedure is dilution in agar plate, the reference method. PMID:24630580

  19. Digital antimicrobial susceptibility testing using the MilliDrop technology.

    PubMed

    Jiang, L; Boitard, L; Broyer, P; Chareire, A-C; Bourne-Branchu, P; Mahé, P; Tournoud, M; Franceschi, C; Zambardi, G; Baudry, J; Bibette, J

    2016-03-01

    We present the MilliDrop Analyzer (MDA), a droplet-based millifluidic system for digital antimicrobial susceptibility testing (D-AST), which enables us to determine minimum inhibitory concentrations (MICs) precisely and accurately. The MilliDrop technology was validated by using resazurin for fluorescence readout, for comparison with standard methodology, and for conducting reproducibility studies. In this first assessment, the susceptibility of a reference Gram-negative strain Escherichia coli ATCC 25922 to gentamicin, chloramphenicol, and nalidixic acid were tested by the MDA, VITEK®2, and broth microdilution as a reference standard. We measured the susceptibility of clinically relevant Gram-positive strains of Staphylococcus aureus to vancomycin, including vancomycin-intermediate S. aureus (VISA), heterogeneous vancomycin-intermediate S. aureus (hVISA), and vancomycin-susceptible S. aureus (VSSA) strains. The MDA provided results which were much more accurate than those of VITEK®2 and standard broth microdilution. The enhanced accuracy enabled us to reliably discriminate between VSSA and hVISA strains. PMID:26803821

  20. Antimicrobial susceptibility testing of Spanish field isolates of Brachyspira hyodysenteriae.

    PubMed

    Hidalgo, A; Carvajal, A; García-Feliz, C; Osorio, J; Rubio, P

    2009-08-01

    This study is the first conducted in Spain to evaluate antimicrobial susceptibility of field isolates of Brachyspira hyodysenteriae. One hundred and eight isolates of the bacterium, recovered from different Spanish swine farms between 2000 and 2007, were investigated. The minimum inhibitory concentrations (MIC) of erythromycin, tylosin, tiamulin, valnemulin, clindamycin and lincomycin were determined using a broth microdilution technique. Most of the isolates showed poor susceptibility to erythromycin (MIC(90)>256 microg/ml), tylosin (MIC(90)>256 microg/ml), clindamycin (MIC(90)>4 microg/ml) and lincomycin (MIC(90)=128 microg/ml). Reduced susceptibility to tiamulin and valnemulin was observed with a MIC>2 microg/ml in 17.6% and 7.41% of the B. hyodysenteriae isolates, respectively. Moreover, a survival analysis permitted the detection of an increasing trend in the MIC values for almost all the antimicrobials used in the treatment of swine dysentery when comparing recent isolates (from 2006 to 2007) with those recovered in earlier years (between 2000 and 2004). PMID:19084246

  1. Antimicrobial susceptibility testing for bovine respiratory disease: getting more from diagnostic results.

    PubMed

    Lubbers, Brian V; Turnidge, John

    2015-02-01

    Bovine respiratory disease (BRD) is one of the most common diseases of cattle worldwide. Given the significant bacterial component of this disease, antimicrobial agents remain one of the mainstays of therapy. However, the potential welfare and economic impact resulting from the selection of inappropriate antimicrobial therapy for BRD poses significant risks to both animal and animal owner. To determine the 'best' antimicrobial agent for a specific case, the decision-making process needs to incorporate all available evidence, often including the results of bacterial culture and antimicrobial susceptibility testing. While antimicrobial susceptibility testing can be a valuable diagnostic tool, integrating the test results into the clinical decision making process can be a challenging experience. This review details the process by which interpretive criteria for susceptibility tests are developed. Principles for how to best integrate antimicrobial susceptibility testing, both at the individual animal test and aggregate test levels, into the clinical decision making process are discussed. Non-traditional testing methodologies and how they may improve susceptibility testing in the future are also reviewed. PMID:25582794

  2. [Detection of cell death markers as a tool for bacterial antimicrobial susceptibility testing].

    PubMed

    Mlynárčik, P; Kolář, M

    2016-01-01

    Antimicrobial resistance among nosocomial pathogens has emerged as one of the most important health care problems in the new millennium. In this review, we present new methods for bacterial antimicrobial susceptibility testing, based on the detection of antibiotic-mediated cell death markers that could provide valuable alternatives to existing phenotypic approaches in the very near future. PMID:27467325

  3. Use of a proposed antimicrobial susceptibility testing method for Haemophilus parasuis.

    PubMed

    Dayao, Denise Ann E; Kienzle, Marco; Gibson, Justine S; Blackall, Patrick J; Turni, Conny

    2014-08-27

    The aim of this study was to examine the antimicrobial susceptibility of 97 Haemophilus parasuis cultured from Australian pigs. As there is no existing standard antimicrobial susceptibility technique available for H. parasuis, methods utilising the supplemented media, BA/SN for disc diffusion and test medium broth (TMB) for a microdilution technique, were initially evaluated with the reference strains recommended by the Clinical and Laboratory Standards Institute. The results of the media evaluation suggested that BA/SN and TMB can be used as suitable media for susceptibility testing of H. parasuis. The proposed microdilution technique was then used with 97 H. parasuis isolates and nine antimicrobial agents. The study found that Australian isolates showed elevated minimum inhibitory concentrations (MICs) for ampicillin (1%), penicillin (2%), erythromycin (7%), tulathromycin (9%), tilmicosin (22%), tetracycline (31%) and trimethoprim-sulfamethoxazole (40%). This study has described potential antimicrobial susceptibility methods for H. parasuis and has detected a low percentage of Australian H. parasuis isolates with elevated antimicrobial MICs. PMID:24984947

  4. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria.

    PubMed

    Brown-Elliott, Barbara A; Nash, Kevin A; Wallace, Richard J

    2012-07-01

    Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria. PMID:22763637

  5. Antimicrobial Susceptibility Testing, Drug Resistance Mechanisms, and Therapy of Infections with Nontuberculous Mycobacteria

    PubMed Central

    Nash, Kevin A.; Wallace, Richard J.

    2012-01-01

    Summary: Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria. PMID:22763637

  6. Antimicrobial susceptibility testing in 90 min by bacterial cell count monitoring

    PubMed Central

    Broeren, M A C; Maas, Y; Retera, E; Arents, N L A

    2013-01-01

    The rise in antimicrobial resistance has become a serious global health problem. Restrictive use of antibiotics seems the only option to temper this accession since research in new antibiotics has halted. Antimicrobial stewardship programmes rely on quick access to susceptibility data. This study evaluated the concept of bacterial cell count monitoring as a fast method to determine susceptibility. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains were tested for amoxicillin/piperacillin and gentamicin by three conventional methods (VITEK2®, Etest® and broth-macrodilution). Bacterial cell count monitoring reliably predicted susceptibility after 90 min for Escherichia coli and after 120 min for Pseudomonas aeruginosa and Staphylococcus aureus without any minor, major or very major discrepancies. Time-to-result was reduced by 74%, 83% and 76%, respectively. Bacterial cell count monitoring shows great potential for rapid susceptibility testing. PMID:22390723

  7. Antimicrobial susceptibility testing in 90 min by bacterial cell count monitoring.

    PubMed

    Broeren, M A C; Maas, Y; Retera, E; Arents, N L A

    2013-03-01

    The rise in antimicrobial resistance has become a serious global health problem. Restrictive use of antibiotics seems the only option to temper this accession since research in new antibiotics has halted. Antimicrobial stewardship programmes rely on quick access to susceptibility data. This study evaluated the concept of bacterial cell count monitoring as a fast method to determine susceptibility. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains were tested for amoxicillin/piperacillin and gentamicin by three conventional methods (VITEK2(®) , Etest(®) and broth-macrodilution). Bacterial cell count monitoring reliably predicted susceptibility after 90 min for Escherichia coli and after 120 min for Pseudomonas aeruginosa and Staphylococcus aureus without any minor, major or very major discrepancies. Time-to-result was reduced by 74%, 83% and 76%, respectively. Bacterial cell count monitoring shows great potential for rapid susceptibility testing. PMID:22390723

  8. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices §...

  9. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices §...

  10. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices §...

  11. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices §...

  12. 21 CFR 866.1700 - Culture medium for antimicrobial susceptibility tests.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Culture medium for antimicrobial susceptibility tests. 866.1700 Section 866.1700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Diagnostic Devices §...

  13. Rapid Bead-Based Antimicrobial Susceptibility Testing by Optical Diffusometry

    PubMed Central

    Chung, Chih-Yao; Wang, Jhih-Cheng; Chuang, Han-Sheng

    2016-01-01

    This study combined optical diffusometry and bead-based immunoassays to develop a novel technique for quantifying the growth of specific microorganisms and achieving rapid AST. Diffusivity rises when live bacteria attach to particles, resulting in additional energy from motile microorganisms. However, when UV-sterilized (dead) bacteria attach to particles, diffusivity declines. The experimental data are consistent with the theoretical model predicted according to the equivalent volume diameter. Using this diffusometric platform, the susceptibility of Pseudomonas aeruginosa to the antibiotic gentamicin was tested. The result suggests that the proliferation of bacteria is effectively controlled by gentamicin. This study demonstrated a sensitive (one bacterium on single particles) and time-saving (within 2 h) platform with a small sample volume (~0.5 μL) and a low initial bacteria count (50 CFU per droplet ~ 105 CFU/mL) for quantifying the growth of microorganisms depending on Brownian motion. The technique can be applied further to other bacterial strains and increase the success of treatments against infectious diseases in the near future. PMID:26863001

  14. Rapid Bead-Based Antimicrobial Susceptibility Testing by Optical Diffusometry.

    PubMed

    Chung, Chih-Yao; Wang, Jhih-Cheng; Chuang, Han-Sheng

    2016-01-01

    This study combined optical diffusometry and bead-based immunoassays to develop a novel technique for quantifying the growth of specific microorganisms and achieving rapid AST. Diffusivity rises when live bacteria attach to particles, resulting in additional energy from motile microorganisms. However, when UV-sterilized (dead) bacteria attach to particles, diffusivity declines. The experimental data are consistent with the theoretical model predicted according to the equivalent volume diameter. Using this diffusometric platform, the susceptibility of Pseudomonas aeruginosa to the antibiotic gentamicin was tested. The result suggests that the proliferation of bacteria is effectively controlled by gentamicin. This study demonstrated a sensitive (one bacterium on single particles) and time-saving (within 2 h) platform with a small sample volume (~0.5 μL) and a low initial bacteria count (50 CFU per droplet ~ 105 CFU/mL) for quantifying the growth of microorganisms depending on Brownian motion. The technique can be applied further to other bacterial strains and increase the success of treatments against infectious diseases in the near future. PMID:26863001

  15. Antimicrobial Disk Susceptibility Testing of Leptospira spp. Using Leptospira Vanaporn Wuthiekanun (LVW) Agar.

    PubMed

    Wuthiekanun, Vanaporn; Amornchai, Premjit; Langla, Sayan; White, Nicholas J; Day, Nicholas P J; Limmathurotsakul, Direk; Peacock, Sharon J

    2015-08-01

    Leptospira Vanaporn Wuthiekanun (LVW) agar was used to develop a disk diffusion assay for Leptospira spp. Ten pathogenic Leptospira isolates were tested, all of which were susceptible to 17 antimicrobial agents (amoxicillin/clavulanic acid, amoxicillin, azithromycin, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, doripenem, doxycycline, gentamicin, linezolid, nitrofurantoin, penicillin, piperacillin/tazobactam, and tetracycline). All 10 isolates had no zone of growth inhibition for four antimicrobials (fosfomycin, nalidixic acid, rifampicin, and trimethoprim/sulfamethoxazole). Of the ten Leptospira, seven had a growth inhibition zone of ≤ 21 mm for aztreonam, the zone diameter susceptibility break point for Enterobacteriaceae. This assay could find utility as a simple screening method during the epidemiological surveillance of antimicrobial resistance in Leptospira spp. PMID:26055750

  16. CLSI performance standards for antimicrobial susceptibility testing of bacteria isoloated from aquatic animals; second information supplement. CLSI document VET03/VET04-S2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The supplemental information presented in this document is intended for use with the antimicrobial susceptibility testing procedures published in the following Clinical and Laboratory Standards Institute (CLSI) approved documents VET03-A Methods for Antimicrobial Disk Susceptibility Testing of Bacte...

  17. Bacterial Cytological Profiling (BCP) as a Rapid and Accurate Antimicrobial Susceptibility Testing Method for Staphylococcus aureus

    PubMed Central

    Quach, D.T.; Sakoulas, G.; Nizet, V.; Pogliano, J.; Pogliano, K.

    2016-01-01

    Successful treatment of bacterial infections requires the timely administration of appropriate antimicrobial therapy. The failure to initiate the correct therapy in a timely fashion results in poor clinical outcomes, longer hospital stays, and higher medical costs. Current approaches to antibiotic susceptibility testing of cultured pathogens have key limitations ranging from long run times to dependence on prior knowledge of genetic mechanisms of resistance. We have developed a rapid antimicrobial susceptibility assay for Staphylococcus aureus based on bacterial cytological profiling (BCP), which uses quantitative fluorescence microscopy to measure antibiotic induced changes in cellular architecture. BCP discriminated between methicillin-susceptible (MSSA) and -resistant (MRSA) clinical isolates of S. aureus (n = 71) within 1–2 h with 100% accuracy. Similarly, BCP correctly distinguished daptomycin susceptible (DS) from daptomycin non-susceptible (DNS) S. aureus strains (n = 20) within 30 min. Among MRSA isolates, BCP further identified two classes of strains that differ in their susceptibility to specific combinations of beta-lactam antibiotics. BCP provides a rapid and flexible alternative to gene-based susceptibility testing methods for S. aureus, and should be readily adaptable to different antibiotics and bacterial species as new mechanisms of resistance or multidrug-resistant pathogens evolve and appear in mainstream clinical practice. PMID:26981574

  18. Bacterial Cytological Profiling (BCP) as a Rapid and Accurate Antimicrobial Susceptibility Testing Method for Staphylococcus aureus.

    PubMed

    Quach, D T; Sakoulas, G; Nizet, V; Pogliano, J; Pogliano, K

    2016-02-01

    Successful treatment of bacterial infections requires the timely administration of appropriate antimicrobial therapy. The failure to initiate the correct therapy in a timely fashion results in poor clinical outcomes, longer hospital stays, and higher medical costs. Current approaches to antibiotic susceptibility testing of cultured pathogens have key limitations ranging from long run times to dependence on prior knowledge of genetic mechanisms of resistance. We have developed a rapid antimicrobial susceptibility assay for Staphylococcus aureus based on bacterial cytological profiling (BCP), which uses quantitative fluorescence microscopy to measure antibiotic induced changes in cellular architecture. BCP discriminated between methicillin-susceptible (MSSA) and -resistant (MRSA) clinical isolates of S. aureus (n = 71) within 1-2 h with 100% accuracy. Similarly, BCP correctly distinguished daptomycin susceptible (DS) from daptomycin non-susceptible (DNS) S. aureus strains (n = 20) within 30 min. Among MRSA isolates, BCP further identified two classes of strains that differ in their susceptibility to specific combinations of beta-lactam antibiotics. BCP provides a rapid and flexible alternative to gene-based susceptibility testing methods for S. aureus, and should be readily adaptable to different antibiotics and bacterial species as new mechanisms of resistance or multidrug-resistant pathogens evolve and appear in mainstream clinical practice. PMID:26981574

  19. Antimicrobial susceptibility testing of Neisseria gonorrhoeae and implications for epidemiology and therapy.

    PubMed Central

    Fekete, T

    1993-01-01

    Antimicrobial susceptibility testing (AST) of Neisseria gonorrhoeae has been under development since the early days of antimicrobial agents. However, it is rarely applied to clinical isolates today. The history of the various in vitro tests to determine the susceptibility of N. gonorrhoeae to antibiotics is rich with evidence that these results predict response to therapy for almost all agents tested. Further, AST is a useful and important aspect of strain characterization and disease epidemiology in conjunction with the more specific but laborious techniques of auxotyping, serotyping, and plasmid analysis. Current technology has overcome many of the objections to AST for N. gonorrhoeae with standardization of test media and the development of an accurate disk diffusion AST method that is suited to most clinical laboratories regardless of volume or level of technical expertise. Ironically, the very low level of resistance to the current primary treatment strategy in the United States, ceftriaxone or another potent cephalosporin, makes the use of AST somewhat superfluous. PMID:8457978

  20. EUCAST recommendations for antimicrobial susceptibility testing applied to the three main Campylobacter species isolated in humans.

    PubMed

    Sifré, Elodie; Salha, Ben Amor; Ducournau, Astrid; Floch, Pauline; Chardon, Hubert; Mégraud, Francis; Lehours, Philippe

    2015-12-01

    Antimicrobial susceptibility testing of Campylobacter isolates is of great importance for treatment options especially in systemic diseases. The European Committee for Antimicrobial Susceptibility Testing (EUCAST) recently proposed epidemiological cut-offs (ECOFFs) for a limited number of antimicrobial compounds and for Campylobacter jejuni and Campylobacter coli only. In the present study, the EUCAST method was used after minor modifications to define antimicrobial susceptibility patterns for, 1997 C. jejuni, 419 C. coli and 100 Campylobacter fetus strains received at the French National Reference Center for Campylobacters and Helicobacters. Our results show that the ECOFFs defined by EUCAST for tetracycline and ciprofloxacin can be used for C. jejuni and C. coli. The same ECOFF can be used for erythromycin for the three species. The C. jejuni and C. coli ECOFFs for ciprofloxacin however cannot be applied to C. fetus. We also provide data to categorise two 2 β-lactams of interest for systemic diseases, ampicillin and amoxicillin+clavulanate, for the three species. PMID:26519770

  1. In vitro susceptibility testing of nonsporing anaerobes to ten antimicrobial agents.

    PubMed

    Rao, P S; Shivananda, P G

    2000-07-01

    Antibiotic susceptibility was performed on sixty clinical isolates of nonsporing anaerobes against ten antimicrobial agents. The test was performed on Muller Hinton Agar and Wilkins Chalgren blood agar by preparing suspension of freshly isolated colonies in BHI broth. Apart from Metronidazole and Chloramphenicol newer antibiotics like Minocycline, Secnidazole, Tinidazole, Clarithromycin, Roxithromycin were also tried. Antimicrobial agents like Metronidazole, Secnidazole, Tinidazole and Minocycline were 100% sensitive, followed by Chloramphenicol, Clarithromycin and Roxithromycin. These newer agents can be good alternatives for the treatment of non sporing anaerobes. PMID:11218673

  2. In vitro susceptibility testing of nonsporing anaerobes to ten antimicrobial agents.

    PubMed

    Rao, P S; Shivananda, P G

    2000-04-01

    Antibiotic Susceptibility was performed on sixty clinical isolates of nonsporing anaerobes against ten antimicrobial agents. The test was performed on Muller Hinton Agar and Wilkins Chalgren blood agar by preparing suspension of freshly isolated colonies in BHI broth. Apart from Metronidazole and Chloramphenicol newer antibiotics like Minocycline, Secnidazole, Tinidazole, Clarithromycin, Roxithromycin were also tried. Antimicrobial agents like metronidazole, Secnidazole, Tinidazole and Minocycline were 100% sensitive, followed by Chloramphenicol, Clarithromycin and Roxithromycin. These newer agents can be good alternatives for the treatment of non sporing anaerobes. PMID:11217270

  3. A rapid antimicrobial susceptibility test based on single-cell morphological analysis.

    PubMed

    Choi, Jungil; Yoo, Jungheon; Lee, Mincheol; Kim, Eun-Geun; Lee, Ji Soo; Lee, Seungok; Joo, Seik; Song, Sang Hoon; Kim, Eui-Chong; Lee, Jung Chan; Kim, Hee Chan; Jung, Yong-Gyun; Kwon, Sunghoon

    2014-12-17

    A rapid antibiotic susceptibility test (AST) is desperately needed in clinical settings for fast and appropriate antibiotic administration. Traditional ASTs, which rely on cell culture, are not suitable for urgent cases of bacterial infection and antibiotic resistance owing to their relatively long test times. We describe a novel AST called single-cell morphological analysis (SCMA) that can determine antimicrobial susceptibility by automatically analyzing and categorizing morphological changes in single bacterial cells under various antimicrobial conditions. The SCMA was tested with four Clinical and Laboratory Standards Institute standard bacterial strains and 189 clinical samples, including extended-spectrum β-lactamase-positive Escherichia coli and Klebsiella pneumoniae, imipenem-resistant Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant Enterococci from hospitals. The results were compared with the gold standard broth microdilution test. The SCMA results were obtained in less than 4 hours, with 91.5% categorical agreement and 6.51% minor, 2.56% major, and 1.49% very major discrepancies. Thus, SCMA provides rapid and accurate antimicrobial susceptibility data that satisfy the recommended performance of the U.S. Food and Drug Administration. PMID:25520395

  4. Antimicrobial susceptibility testing of Australian isolates of Brachyspira hyodysenteriae using a new broth dilution method.

    PubMed

    Karlsson, Märit; Oxberry, Sophy L; Hampson, David J

    2002-01-01

    The antimicrobial susceptibilities of 76 field isolates of Brachyspira hyodysenteriae from different states of Australia were tested in a newly developed broth dilution procedure. The antimicrobial agents used were tiamulin, valnemulin, tylosin, erythromycin, lincomycin and clindamycin. The results from the broth dilution susceptibility testing of 39 of the isolates were compared with results obtained for the same isolates using the agar dilution method. Amongst the isolates tested by broth dilution, 17 were from three farms and had been collected over a number of years. Their pulsed field gel electrophoresis pattern previously had been determined. The broth dilution technique was simple to use, less labor intensive than agar dilution, and gave clear end points. The results obtained using the two methods generally corresponded well, although in a few cases the MIC obtained by broth dilution were lower than those with agar dilution. For the 76 isolates tested by broth dilution, the MIC(90) (mg/l) was: tiamulin, 1; valnemulin, 0.5; tylosin>256; erythromycin>256; lincomycin, 64 and clindamycin, 16. Only minor differences in susceptibility patterns were found amongst isolates from different Australian states. Over all the isolates, and also amongst the isolates obtained from different years on the three farms, there was no trend for the susceptibility of the isolates to alter with time. PMID:11731165

  5. Rapid antimicrobial susceptibility testing of clinical isolates by digital time-lapse microscopy.

    PubMed

    Fredborg, M; Rosenvinge, F S; Spillum, E; Kroghsbo, S; Wang, M; Sondergaard, T E

    2015-12-01

    Rapid antimicrobial susceptibility testing (AST) is essential for early and appropriate therapy. Methods with short detection time enabling same-day treatment optimisation are highly favourable. In this study, we evaluated the potential of a digital time-lapse microscope system, the oCelloScope system, to perform rapid AST. The oCelloScope system demonstrated a very high accuracy (96% overall agreement) when determining the resistance profiles of four reference strains, nine clinical isolates, including multi-drug-resistant isolates, and three positive blood cultures. AST of clinical isolates (168 antimicrobial agent-organism combinations) demonstrated 3.6% minor, no major and 1.2% very major errors of the oCelloScope system compared to conventional susceptibility testing, as well as a rapid and correct phenotypic detection of strains with methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL) profiles. The net average time-to-result was 108 min, with 95% of the results being available within 180 min. In conclusion, this study strongly indicates that the oCelloScope system holds considerable potential as an accurate and sensitive AST method with short time-to-result, enabling same-day targeted antimicrobial therapy, facilitating antibiotic stewardship and better patient management. A full-scale validation of the oCelloScope system including more isolates is necessary to assess the impact of using it for AST. PMID:26407621

  6. Antimicrobial susceptibility of Mycoplasma hyorhinis.

    PubMed

    Wu, C C; Shryock, T R; Lin, T L; Faderan, M; Veenhuizen, M F

    2000-09-15

    A broth microdilution technique was used to determine the antimicrobial susceptibility of 15 field isolates of Mycoplasma hyorhinis to 10 antimicrobial agents, representative of different classes, and contrasting newer agents to existing ones. For the macrolides, the MIC(90) for tylosin and tilmicosin was 1 and 4 microg/ml, respectively, but was > or = 16 microg/ml for erythromycin. Tetracycline, lincomycin and enrofloxacin each had an MIC(90) of 2 microg/ml. The mycoplasma had similar levels of susceptibility to the aminoglycoside and aminocyclictol classes exhibiting an MIC(90) of 4 microg/ml for gentamicin and 2 microg/ml for spectinomycin. The isolates exhibited high MICs to trimethoprim/sulfamethoxazole with an MIC(90) > or = 16/304 microg/ml. In summary, M. hyorhinis isolates from the US had low MICs against a variety of antimicrobials tested, with the exception of erythromycin and trimethoprim/sulfamethoxazole. PMID:10925038

  7. Antimicrobial susceptibility testing of Brachyspira intermedia and Brachyspira pilosicoli isolates from Australian chickens.

    PubMed

    Hampson, D J; Stephens, C P; Oxberry, S L

    2006-02-01

    Susceptibilities of predominantly Australian isolates of the pathogenic intestinal spirochaetes Brachyspira intermedia (n = 25) and Brachyspira pilosicoli (n = 17) from chickens were tested in agar dilution against four concentrations each of the antimicrobials tiamulin, lincomycin, tylosin, metronidazole, tetracycline and ampicillin. Based on available minimum inhibitory concentration (MIC) breakpoint values for Brachyspira hyodysenteriae or other Gram-negative enteric veterinary pathogens, isolates of both species generally were susceptible to tiamulin, lincomycin, metronidazole and tetracycline. Although not classed as resistant, four isolates of B. intermedia had an elevated MIC range for tiamulin (1 to 4 mg/l), 11 isolates of B. intermedia and five of B. pilosicoli had an elevated MIC range for lincomycin (10 to 50 mg/l), one isolate of B. pilosicoli had an elevated MIC range for tetracycline (10 to 20 mg/l), and one isolate of B. intermedia and five of B. pilosicoli had an elevated MIC range for ampicillin (10 to 50 mg/l). A clear lack of susceptibility to tylosin (MIC > 4 mg/l) was seen in 11 isolates each of B. intermedia and B. pilosicoli, and to ampicillin (MIC > 32 mg/l) in two isolates of B. pilosicoli. These data suggest that some resistance to common antimicrobials exists among intestinal spirochetes obtained from laying hens and supports the need of MIC data for clinical isolates before any treatment is considered. PMID:16448937

  8. Comparison of an Automated System with Conventional Identification and Antimicrobial Susceptibility Testing

    PubMed Central

    Duggal, Shalini; Gaind, Rajni; Tandon, Neha; Deb, Manorama; Chugh, Tulsi Das

    2012-01-01

    The present study was designed to compare a fully automated identification/antibiotic susceptibility testing (AST) system BD Phoenix (BD) for its efficacy in rapid and accurate identification and AST with conventional manual methods and to determine if the errors reported in AST, such as the (very major errors) VME (false susceptibility), (major errors) ME (false resistance), and (minor errors) MiE (intermediate category interpretation) were within the range certified by FDA. Identification and antimicrobial susceptibility test results of eighty-five clinical isolates including both gram-positive and negative were compared on Phoenix considering the results obtained from conventional manual methods of identification and disc diffusion testing of antibiotics as standards for comparison. Phoenix performed favorably well. There was 100% concordance in identification for gram-negative isolates and 94.83% for gram-positive isolates. In seven cases, Phoenix proved better than conventional identification. For antibiotic results, categorical agreement was 98.02% for gram-positive and 95.7% for gram-negative isolates. VME was 0.33%, ME 0.66%, MiE 0.99% for gram-positive isolates and 1.23% VME, 1.23% ME, and 1.85% MiE for gram-negative isolates. Therefore, this automated system can be used as a tool to facilitate early identification and susceptibility pattern of aerobic bacteria in routine microbiology laboratories. PMID:23762748

  9. Antimicrobial Susceptibility Test with Plasmonic Imaging and Tracking of Single Bacterial Motions on Nanometer Scale.

    PubMed

    Syal, Karan; Iriya, Rafael; Yang, Yunze; Yu, Hui; Wang, Shaopeng; Haydel, Shelley E; Chen, Hong-Yuan; Tao, Nongjian

    2016-01-26

    Antimicrobial susceptibility tests (ASTs) are important for confirming susceptibility to empirical antibiotics and detecting resistance in bacterial isolates. Currently, most ASTs performed in clinical microbiology laboratories are based on bacterial culturing, which take days to complete for slowly growing microorganisms. A faster AST will reduce morbidity and mortality rates and help healthcare providers administer narrow spectrum antibiotics at the earliest possible treatment stage. We report the development of a nonculture-based AST using a plasmonic imaging and tracking (PIT) technology. We track the motion of individual bacterial cells tethered to a surface with nanometer (nm) precision and correlate the phenotypic motion with bacterial metabolism and antibiotic action. We show that antibiotic action significantly slows down bacterial motion, which can be quantified for development of a rapid phenotypic-based AST. PMID:26637243

  10. Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China

    PubMed Central

    Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

    2015-01-01

    Objectives. Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Methods. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. Results. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Conclusions. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians. PMID:26351633

  11. Improved Broth Microdilution Method for Antimicrobial Susceptibility Testing of Francisella Noatunensis Orientalis.

    PubMed

    Soto, Esteban; Halliday-Simmonds, Iona; Francis, Stewart; Fraites, Trellor; Martínez-López, Beatriz; Wiles, Judy; Hawke, John P; Endris, Richard D

    2016-09-01

    In this project we optimized a minimal inhibitory concentration testing protocol for Francisella noatunensis orientalis. Thirty-three F. noatunensis orientalis isolates recovered from different fish species and locations were tested, and Escherichia coli ATCC 25922 was used as a quality control reference strain. A modified cation-adjusted Mueller Hinton broth supplemented with 2% IsoVitalex and 0.1% glucose (MMH) was tested at a pH of 6.4 ± 0.1, 7.1 ± 0.1, and 7.3 ± 0.1. Growth curves generated for F. noatunensis orientalis indicated that MMH at a pH of 6.4 ± 0.1 provided optimal growth. There were no significant differences in the growth curves obtained from isolates recovered from different fish species or from fresh or marine water. The pH of 6.4 ± 0.1 in the MMH media interfered with the inhibitory properties of the potentiated sulfonamides (ormetoprim-sulfadimethoxine and trimethoprim-sulfamethoxazole) when using the E. coli ATCC reference strain. Minimal inhibitory concentrations of eight antimicrobials (gentamicin, enrofloxacin, ampicillin, oxytetracycline, erythromycin, florfenicol, flumequine, and oxolinic acid) were similar for all F. noatunensis orientalis isolates. The in vitro susceptibility data provided here can provide a baseline for monitoring the development of antimicrobial resistance among F. noatunensis orientalis isolates, as well as provide valuable data in the development of potential therapeutics. Received October 27, 2015; accepted April 13, 2016. PMID:27484609

  12. Detailed Methodology and Implementation of a Semiautomated Serial Dilution Microtechnique for Antimicrobial Susceptibility Testing

    PubMed Central

    MacLowry, James D.; Jaqua, Mary J.; Selepak, Sally T.

    1970-01-01

    The detailed methodology and implementation of a semiautomatic microtechnique for performing serial dilution antimicrobial susceptibility studies are described. Quantitative susceptibility studies to a battery of antimicrobials are performed routinely on all significant clinical isolates. Results are reported as the minimal inhibitory concentration in micrograms per milliliter of broth. Guidelines relating standard doses of antimicrobials with expected blood and urine levels are presented to facilitate the use of the quantitative data. This microtechnique is used to measure serum and other body fluid levels of antimicrobial agents to document the level attained with a specific course of therapy. This technique is highly reproducible and has a high correlation with, and is at least 10 times faster than, standard glass tube techniques. PMID:4917462

  13. In vitro antimicrobial susceptibility testing of Helicobacter felis, H. bizzozeronii, and H. salomonis.

    PubMed

    Van den Bulck, K; Decostere, A; Gruntar, I; Baele, M; Krt, B; Ducatelle, R; Haesebrouck, F

    2005-07-01

    The susceptibilities of Helicobacter felis (15 strains), H. bizzozeronii (7 strains), and H. salomonis (3 strains) to 10 antimicrobial agents were investigated by determination of the MIC using the agar dilution method. No consistent differences were noticed between the different Helicobacter species, which were all highly susceptible to ampicillin, clarithromycin, tetracycline, tylosin, enrofloxacin, gentamicin, and neomycin, as demonstrated by low MICs. Higher MICs were obtained for lincomycin (up to 8 microg/ml) and spectinomycin (up to 4 microg/ml). Two H. felis strains showed a MIC of 16 microg/ml for metronidazole, suggesting acquired resistance to this antimicrobial agent. PMID:15980383

  14. Development of an Antimicrobial Susceptibility Testing Method Suitable for Performing During Space Flight

    NASA Technical Reports Server (NTRS)

    Jorgensen, James H.; Skweres, Joyce A.; Mishra S. K.; McElmeel, M. Letticia; Maher, Louise A.; Mulder, Ross; Lancaster, Michael V.; Pierson, Duane L.

    1997-01-01

    Very little is known regarding the affects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a Space Shuttle mission. Specially prepared susceptibility test research cards (bioMerieux Vitek, Hazelwood, MO) were designed to include 6-11 serial two-fold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a Beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim/sulfamethoxazole. Minimal inhibitory concentrations (MICS) of the drugs were determined by visual reading of color endpoints in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue(Trademark), Accumed International, Westlake, OH). This study has demonstrated reproducible susceptibility results when testing isolates of Staphylococcus aurezis, Group A Streptococcus, Enterococcusfaecalis, Escherichia coli (beta-lactamase positive and negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomoiias aeruginosa. In some instances, the MICs were comparable to those determined using a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values, that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the Space Shuttle, storage of inoculated cards at refrigeration temperature aboard the Space Shuttle until experiment initiation, then incubation of the cards for 18-48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4-8 C to accommodate the mission's time schedule and the astronauts' activities. For comparison, ground-based control

  15. Assessment of Etest as an alternative to agar dilution for antimicrobial susceptibility testing of Neisseria gonorrhoeae.

    PubMed

    Liu, Hsi; Taylor, Thomas H; Pettus, Kevin; Trees, David

    2014-05-01

    We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest. PMID:24554750

  16. Assessment of Etest as an Alternative to Agar Dilution for Antimicrobial Susceptibility Testing of Neisseria gonorrhoeae

    PubMed Central

    Taylor, Thomas H.; Pettus, Kevin; Trees, David

    2014-01-01

    We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest. PMID:24554750

  17. Evaluation of Vitek2 and BD Phoenix in antimicrobial susceptibility testing of Acinetobacter baumannii and Pseudomonas aeruginosa.

    PubMed

    Jekarl, Dong Wook; Han, Sang Bong; Kim, Yoon Joo; Shin, Sang Hyun; Park, Kang Gyun; Park, Jung Jun; Han, Kyungja; Park, Yeon-Joon

    2010-08-01

    The accuracy of antimicrobial susceptibility testing of Vitek2 and BD Phoenix against Acinetobacter baumannii and Pseudomonas aeruginosa was evaluated. Both systems showed overall categoric agreement of < or =90% for cefepime and ceftazidime against A. baumannii and imipenem and cefepime (and ceftazidime with Vitek2) against P. aeruginosa because of high minor error rates. PMID:20638609

  18. Miniaturized Antimicrobial Susceptibility Test by Combining Concentration Gradient Generation and Rapid Cell Culturing

    PubMed Central

    Kim, Samuel C.; Cestellos-Blanco, Stefano; Inoue, Keisuke; Zare, Richard N.

    2015-01-01

    Effective treatment of bacterial infection relies on timely diagnosis and proper prescription of antibiotic drugs. The antimicrobial susceptibility test (AST) is one of the most crucial experimental procedures, providing the baseline information for choosing effective antibiotic agents and their dosages. Conventional methods, however, require long incubation times or significant instrumentation costs to obtain test results. We propose a lab-on-a-chip approach to perform AST in a simple, economic, and rapid manner. Our assay platform miniaturizes the standard broth microdilution method on a microfluidic device (20 × 20 mm) that generates an antibiotic concentration gradient and delivers antibiotic-containing culture media to eight 30-nL chambers for cell culture. When tested with 20 μL samples of a model bacterial strain (E. coli ATCC 25922) treated with ampicillin or streptomycin, our method allows for the determination of minimum inhibitory concentrations consistent with the microdilution test in three hours, which is almost a factor of ten more rapid than the standard method. PMID:27025635

  19. [The annual changes in antimicrobial susceptibility test results of Pseudomonas aeruginosa isolates from the Kinki district].

    PubMed

    Fukuda, Saori; Komatsu, Masaru; Nakamura, Tatuya; Jikimoto, Takumi; Nishio, Hisaaki; Yamasaki, Katsutoshi; Satoh, Kaori; Toda, Hirofumi; Orita, Tamaki; Sueyoshi, Noriyuki; Kita, Machiko; Nishi, Isao; Akagi, Masahiro; Higuchi, Takeshi; Kofuku, Tomomi; Nakai, Isako; Ono, Tamotsu; Kida, Kaneyuki; Ohama, Masanobu; Watari, Hideo; Shimura, Satoshi; Niki, Makoto; Kuchibiro, Tomokazu; Wada, Yasunao

    2016-04-01

    A study was conducted of the 1,225 Pseudomonas aeruginosa strains that were isolated at 20 medical institutions in the Kinki district between 2011 and 2013 to determine their antimicrobial susceptibility and to characterize the strains of multidrug-resistant Pseudomonas aeruginosa (MDRP) and the metallo-β-lactamase (MBL) -producing strains. The MIC50/MIC90 values (μg/mL) of the various antimicrobial agents were as follows: imipenem, 2/>8; meropenem, 1/>8; doripenem, 0.5/8; biapenem, 1/>8; tazobactam/piperacillin, 8/>64; piperacillin, 8/>64; sulbactam/cefoperazone, 8/64; cefepime, 4/16; cefozopran, 2/>16; aztreonam, 8/>16; amikacin, 4/16; levofloxacin, 1/>4; and ciprofloxacin, 0.25/>2. From the viewpoint of the annual changes in the susceptibility rates (according to the CLSI guidelines [M100-S22]), the susceptibility to tazobactam/piperacillin, piperacillin, cefepime, cefozopran and aztreonam decreased in 2013. On the other hand, two antimicrobial agents showed high susceptibility rates each year; amikacin (94.0-95.6%) showed the highest rate, followed by doripenem (80.3-82.6%). With the exception of amikacin, there were substantial inter-institutional differences in antimicrobial susceptibility. In comparison to the previous CLSI guidelines (M100-S21), the new CLSI guidelines (M100-S22) on the use of carbapenems and penicillins show that the MIC80 has been affected. The MDRP detection rates in 2011, 2012 and 2013 were 1.8% (8 strains), 1.8% (8 strains), and 2.8% (10 strains), respectively. The MBL detection rates were as follows: bla(VIM-2), 0.2% (1 strain) in 2011; bla(IMP-1), 0.9% (4 strains) in 2012, and 1.7% (6 strains, including bla(IMP-1) [3 strains], bla(IMP-2) [2 strains] and bla(VIM-2) [1 strain]) in 2013. PMID:27544978

  20. An in situ antimicrobial susceptibility testing method based on in vivo measurements of chlorophyll α fluorescence.

    PubMed

    Heliopoulos, Nikolaos S; Galeou, Angeliki; Papageorgiou, Sergios K; Favvas, Evangelos P; Katsaros, Fotios K; Stamatakis, Kostas

    2015-05-01

    Up to now antimicrobial susceptibility testing (AST) methods are indirect and generally involve the manual counting of bacterial colonies following the extraction of microorganisms from the surface under study and their inoculation in a separate procedure. In this work, an in situ, direct and instrumental method for the evaluation and assessment of antibacterial properties of materials and surfaces is proposed. Instead of indirectly determining antibacterial activity using the typical gram(-) test organisms with the subsequent manual colony count or inhibition zone measurement, the proposed procedure, employs photosynthetic gram(-) cyanobacteria deposited directly onto the surface under study and assesses cell proliferation and viability by a quick, accurate and reproducible instrumental chlorophyll fluorescence spectrophotometric technique. In contrast with existing methods of determination of antibacterial properties, it produces high resolution and quantitative results and is so versatile that it could be used to evaluate the antibacterial properties of any compound (organic, inorganic, natural or man-made) under any experimental conditions, depending on the targeted application. PMID:25771834

  1. Identification of veterinary pathogens by use of commercial identification systems and new trends in antimicrobial susceptibility testing of veterinary pathogens.

    PubMed Central

    Watts, J L; Yancey, R J

    1994-01-01

    Veterinary diagnostic microbiology is a unique specialty within microbiology. Although isolation and identification techniques are similar to those used for human pathogens, many veterinary pathogens require unique cultivation or identification procedures. Commercial identification systems provide rapid, accurate identification of human pathogens. However, the accuracy of these systems with veterinary pathogens varies widely depending on the bacterial species and the host animal from which it was isolated. Increased numbers of veterinary strains or species in the data bases of the various systems would improve their accuracy. Current procedures and interpretive criteria used for antimicrobial susceptibility testing of veterinary pathogens are based on guidelines used for human pathogens. The validity of these guidelines for use with veterinary pathogens has not been established. As with fastidious human pathogens, standardized methodologies and quality control isolates are needed for tests of organisms such as Actinobacillus pleuropneumoniae and Haemophilus somnus. Furthermore, interpretive criteria for veterinary antimicrobial agents based on the MIC for veterinary pathogens, the pharmacokinetics of the antimicrobial agent in the host animal, and in vivo efficacy of the antimicrobial agent are needed. This article reviews both the commercial identification systems evaluated with veterinary pathogens and current methods for performing and interpreting antimicrobial susceptibility tests with veterinary pathogens. Recommendations for future improvements in both areas are discussed. PMID:7923054

  2. Quality control guidelines for disk diffusion and broth microdilution antimicrobial susceptibility tests with seven drugs for veterinary applications.

    PubMed

    Odland, B A; Erwin, M E; Jones, R N

    2000-01-01

    This multicenter study proposes antimicrobial susceptibility (MIC and disk diffusion methods) quality control (QC) parameters for seven compounds utilized in veterinary health. Alexomycin, apramycin, tiamulin, tilmicosin, and tylosin were tested by broth microdilution against various National Committee for Clinical Laboratory Standards (NCCLS)-recommended QC organisms (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Streptococcus pneumoniae ATCC 49619, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853). In addition, disk diffusion zone diameter QC limits were determined for apramycin, enrofloxacin, and premafloxacin by using E. coli ATCC 25922, P. aeruginosa ATCC 27853, and S. aureus ATCC 25923. The results from five or six participating laboratories produced >/=99.0% of MICs and >/=95.0% of the zone diameters within suggested guidelines. The NCCLS Subcommittee for Veterinary Antimicrobial Susceptibility Testing has recently approved these ranges for publication in the next M31 document. PMID:10618141

  3. Genetic antimicrobial susceptibility testing in Gram-negative sepsis - impact on time to results in a routine laboratory.

    PubMed

    Kommedal, Øyvind; Aasen, Johanne Lind; Lindemann, Paul Christoffer

    2016-07-01

    Diagnostic testing of positive blood cultures is among the most critical tasks performed by clinical microbiology laboratories, and the total analysis time from sampling to results should be kept as short as possible. By providing identification of pelleted bacteria directly from positive blood-cultures, MALDI-TOF MS opens for relatively low-complex species-adjusted genetic susceptibility testing from the same bacterial pellet. In our lab routine, we prospectively evaluated a rapid in-house real-time PCR targeting the most common aminoglycoside and cephalosporin resistance genes in Escherichia coli and Klebsiella pneumoniae and measured time to preliminary susceptibility reporting for 138 samples. The results were compared to direct phenotypic susceptibility testing with interpretation after 6 h and overnight incubation respectively. Results from the genetic susceptibility testing were available for 69.5% (96/138) of the positive blood cultures within 24 h after sample collection. No phenotypic susceptibility results were available at this time. Compared to overnight direct susceptibility testing, the average time from sample collection to preliminary susceptibility reporting was reduced with 43%, from 45 h and 5 min to 25 h and 44 min, providing an earlier adjustment of antimicrobial therapy for 12 patients. Minor logistic adjustments have the potential to save yet another 4 h. PMID:27197792

  4. Direct disk diffusion test using European Clinical Antimicrobial Susceptibility Testing breakpoints provides reliable results compared with the standard method

    PubMed Central

    Stokkou, Sofia; Geginat, Gernot; Schlüter, Dirk

    2015-01-01

    Sepsis represents a life-threatening infection requiring the immediate start of antibacterial treatment to reduce morbidity. Thus, laboratories use direct antimicrobial susceptibility testing (AST) to rapidly generate preliminary results from positive blood cultures. As the direct AST has not yet been published to be evaluated with EUCAST breakpoints, the purpose of the study was to investigate the reliability of the direct agar diffusion test to correctly produce AST results from positive monobacterial blood cultures compared with the VITEK2-based definitive AST, when current EUCAST breakpoints were used. A total of 428 isolates from unselected monobacterial routine blood cultures and 110 challenge strains were included. Direct agar diffusion-based and standard VITEK2-based AST of 2803 bacterium–drug combinations yielded a total clinical category agreement of 95.47% with 1.28% very major errors and 3.42% combined major and minor errors. On the species level, very major errors were observed in the species–drug combinations Enterococcus spp.–high-level gentamicin (10.87%) and Staphylococcus spp.–rifampicin (5%), only. No very major errors occurred with Enterobacteriaceae and Pseudomonas aeruginosa. In most species–drug combinations, the direct agar diffusion test using EUCAST breakpoints precisely predicted the result of the definitive antibiotic susceptibility test and, thus, it can be used to optimize empiric antibiotic therapy until definitive results are available. PMID:25883798

  5. Direct disk diffusion test using European Clinical Antimicrobial Susceptibility Testing breakpoints provides reliable results compared with the standard method.

    PubMed

    Stokkou, Sofia; Geginat, Gernot; Schlüter, Dirk; Tammer, Ina

    2015-03-01

    Sepsis represents a life-threatening infection requiring the immediate start of antibacterial treatment to reduce morbidity. Thus, laboratories use direct antimicrobial susceptibility testing (AST) to rapidly generate preliminary results from positive blood cultures. As the direct AST has not yet been published to be evaluated with EUCAST breakpoints, the purpose of the study was to investigate the reliability of the direct agar diffusion test to correctly produce AST results from positive monobacterial blood cultures compared with the VITEK2-based definitive AST, when current EUCAST breakpoints were used. A total of 428 isolates from unselected monobacterial routine blood cultures and 110 challenge strains were included. Direct agar diffusion-based and standard VITEK2-based AST of 2803 bacterium-drug combinations yielded a total clinical category agreement of 95.47% with 1.28% very major errors and 3.42% combined major and minor errors. On the species level, very major errors were observed in the species-drug combinations Enterococcus spp.-high-level gentamicin (10.87%) and Staphylococcus spp.-rifampicin (5%), only. No very major errors occurred with Enterobacteriaceae and Pseudomonas aeruginosa. In most species-drug combinations, the direct agar diffusion test using EUCAST breakpoints precisely predicted the result of the definitive antibiotic susceptibility test and, thus, it can be used to optimize empiric antibiotic therapy until definitive results are available. PMID:25883798

  6. Rapid Antimicrobial Susceptibility Testing of Bacillus anthracis, Yersinia pestis, and Burkholderia pseudomallei by Use of Laser Light Scattering Technology.

    PubMed

    Bugrysheva, Julia V; Lascols, Christine; Sue, David; Weigel, Linda M

    2016-06-01

    Rapid methods to determine antimicrobial susceptibility would assist in the timely distribution of effective treatment or postexposure prophylaxis in the aftermath of the release of bacterial biothreat agents such as Bacillus anthracis, Yersinia pestis, or Burkholderia pseudomallei Conventional susceptibility tests require 16 to 48 h of incubation, depending on the bacterial species. We evaluated a method that is based on laser light scattering technology that measures cell density in real time. We determined that it has the ability to rapidly differentiate between growth (resistant) and no growth (susceptible) of several bacterial threat agents in the presence of clinically relevant antimicrobials. Results were available in <4 h for B. anthracis and <6 h for Y. pestis and B. pseudomallei One exception was B. pseudomallei in the presence of ceftazidime, which required >10 h of incubation. Use of laser scattering technology decreased the time required to determine antimicrobial susceptibility by 50% to 75% for B. anthracis, Y. pestis, and B. pseudomallei compared to conventional methods. PMID:26984973

  7. Reliability of Disk Diffusion Test Results for the Antimicrobial Susceptibility Testing of Nosocomial Gram-positive Microorganisms: Is E-test Method Better?

    PubMed Central

    Khalili, Hossein; Soltani, Rasool; Negahban, Sorrosh; Abdollahi, Alireza; Gholami, Keirollah

    2012-01-01

    Disk diffusion test is the usual applicable method for assessing the antimicrobial susceptibility pattern in most institutions and hospitals. The aim of this study was to determine the reliability of resistant-reported results of disk diffusion test for 6 routinely used antibiotics against Gram-positive microorganisms of nosocomial origin, using E-test method. Over a 1-year period, clinical specimens (e.g. blood, tracheal secretions, wound secretions, urine, etc.) were obtained from hospitalized patients with defined nosocomial infection and were cultured. Isolated Gram-positive bacteria underwent disk diffusion test for cephalothin, oxacillin, clindamycin, ciprofloxacin, vancomycin, teicoplanin (only for Enterococci), and meropenem antibiotics. E-test method was performed for all isolates resistant or intermediately sensitive to the disks of any mentioned antibiotics. Data showed compatible results of disk diffusion test with the results of E-test method for cephalothin, oxacillin, ciprofloxacin, vancomycin, and teicoplanin. None of ciprofloxacin- and vancomycin-resistant isolates in disk diffusion test showed sensitivity in E-test method. Significant differences between the results of disk diffusion and E-test methods were observed for clindamycin and meropenem against S.aureus (p = 0.01 and 0.04, respectively) and Enterococcus spp (p = 0.03 and 0.02, respectively). In order to increase the reliability of antimicrobial susceptibility results, it is recommended to perform E-test for nosocomial Gram-positive microorganisms that show antibiotic resistance by disk diffusion test and it is more important for clindamycin and meropenem. PMID:24250479

  8. [Recommendations from MENSURA for selection of antimicrobial agents for susceptibility testing and criteria for the interpretation of antibiograms].

    PubMed

    2000-03-01

    This document includes the recommendations from the Spanish antibiogram committee (The MENSURA group, Mesa Española de Normalización de la Sensibilidad y Resistencia a los Antimicrobianos, under the auspices of the Sociedad Española de Quimioterapia and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica) for the selection of antimicrobials for susceptibility testing. Separate tables for each group of organism with proposed susceptibility and resistance breakpoints are updated and comparatively presented with those of other groups, such us NCCLS, CA-SFM and BSAC. The susceptibility breakpoint tends to identify the fully susceptible population, which probably lacks any specific resistance mechanism. The analysis of MIC distributions for different homogeneous populations (same species) is used to define breakpoints for susceptibility. The resistance breakpoint is based on pharmacological and clinical data obtained when the corresponding antibiotic is administered with a conventional schedule. The primary objective of the Spanish MENSURA group is to contribute to the international consensus on the establishment of breakpoints. PMID:10856132

  9. Comparative assessment of CDS, CLSI disc diffusion and Etest techniques for antimicrobial susceptibility testing of Neisseria gonorrhoeae: a 6-year study

    PubMed Central

    Singh, Vikram; Kakran, Monika; Ramesh, V

    2012-01-01

    Background A variety of techniques are available for antimicrobial susceptibility testing of Neisseria gonorrhoeae. Objective The aim of this study was to find a cost-effective, reliable and easily applicable microbiological method to detect antimicrobial susceptibilities of N. gonorrhoeae in resource-poor countries. Design Prospective study. Setting Male and female STD clinic of Regional STD Teaching, Training and Research Centre, New Delhi, India. Participants N. gonorrhoeae isolates from all male and female patients presenting with acute gonococcal urethritis and cervical discharge. Material and methods A total of 295 consecutive N. gonorrhoeae isolates during 2005–2010 was used to compare the Clinical and Laboratory Standards Institute (CLSI) and CDS disc diffusion technique with Etest by performing antimicrobial susceptibility testing in parallel for penicillin, tetracycline, ceftriaxone, ciprofloxacin and spectinomycin. WHO reference strains were used as controls. Results CDS disc diffusion zones of inhibition showed that complete percentage agreement for penicillin, ciprofloxacin and tetracycline was high with their analogous Etest minimal inhibitory concentrations in comparison to CLSI disc diffusion technique, that is, 91.5%, 92.9% and 99.3% versus 87.5%, 88.5% and 74.9%, respectively. CDS results had less number of major and minor category discrepancies in comparison to CLSI and CDS method showed excellent correlation coefficient (r=1) with Etest for all five antimicrobial agents tested in comparison to CLSI (r=0.92). It was very poor (r=0.61) by CLSI method for tetracycline. The correlation coefficients between the two methods and the Etest were identical if tetracycline was removed from the CLSI analysis. Conclusions The CDS technique is an attractive alternative for N. gonorrhoeae susceptibility testing and is recommended for monitoring the antimicrobial susceptibility in less developed and resource-poor settings to facilitate enhanced antimicrobial

  10. Antimicrobial susceptibility testing for Helicobacter pylori isolates from Brazilian children and adolescents: Comparing agar dilution, E-test, and disk diffusion

    PubMed Central

    Ogata, Silvio Kazuo; Gales, Ana Cristina; Kawakami, Elisabete

    2014-01-01

    Antimicrobial susceptibility testing for Helicobacter pylori is increasingly important due to resistance to the most used antimicrobials agents. Only agar dilution method is approved by CLSI, but it is difficult to perform routinely. We evaluated the reliability of E-test and disk diffusion comparing to agar dilution method on Helicobacter pylori antimicrobial susceptibility testing. Susceptibility testing was performed for amoxicillin, clarithromycin, furazolidone, metronidazole and tetracycline using E-test, disk-diffusion and agar dilution method in 77 consecutive Helicobacter pylori strains from dyspeptic children and adolescents. Resistance rates were: amoxicillin - 10.4%, 9% and 68.8%; clarithromycin - 19.5%, 20.8%, 36.3%; metronidazole - 40.2%33.7%, 38.9%, respectively by agar dilution, E-test and disk diffusion method. Furazolidone and tetracycline showed no resistance rates. Metronidazole presented strong correlation to E-test (r = 0.7992, p < 0.0001) and disk diffusion method (r=-0.6962, p < 0.0001). Clarithromycin presented moderate correlation to E-test (r = 0.6369, p < 0.0001) and disk diffusion method (r=−0.5656, p < 0.0001). Amoxicillin presented weak correlation to E-test (r = 0.3565, p = 0.0015) and disk diffusion (r=−0.3565, p = 0.0015). Tetracycline presented weak correlation with E-test (r = 0.2346, p = 0.04) and furazolidone to disk diffusion (r=−0.0288, p = 0.8038). E-test presented better agreement with gold standard. It is an easy and reliable method for Helicobacter pylori susceptibility testing. Disk diffusion method presented high disagreement and high rates of major errors. PMID:25763052

  11. [Susceptibilities of clinical bacterial isolates to antimicrobial agents. A study mainly focused on imipenem. Research Group for Testing Imipenem Susceptibility on Clinical Isolates].

    PubMed

    Igari, J

    1990-10-01

    We investigated susceptibilities of clinical bacterial isolates to imipenem (IPM) and other antimicrobial agents at 459 hospital laboratories throughout Japan from September to December of 1988. In this study, identification and susceptibility testing were performed at each hospital laboratory and the tests were carried out according to the 1-dilution or 3-dilution disc technique in which susceptibilities are classified into 4 grades: , ++, + and -. IPM had significantly high activity against Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Neisseria gonorrhoeae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae, Salmonella spp., Citrobacter freundii, Proteus mirabilis, Providencia rettgeri, Acinetobacter calcoaceticus, Moraxella catarrhalis, Alcaligenes spp., Peptococcus spp./Peptostreptococcus spp., Bacteroides fragilis and Bacteroides spp. and should slightly lower activities on coagulase-negative staphylococci (CNS), Enterococcus faecalis, Haemophilus influenzae, Serratia marcescens, Proteus vulgaris, Providencia stuartii and Pseudomonas aeruginosa than on the above mentioned bacteria. In a comparative study on activities of IPM against bacteria from different clinical sources, no remarkable differences were found due to different sources among S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, C. freundii, P. mirabilis or A. calcoaceticus, whereas slight differences were found among Staphylococcus aureus, CNS, S. marcescens and P. aeruginosa. PMID:2086814

  12. Comparison of Citrated Human Blood, Citrated Sheep Blood, and Defibrinated Sheep Blood Mueller-Hinton Agar Preparations for Antimicrobial Susceptibility Testing of Streptococcus pneumoniae Isolates ▿

    PubMed Central

    Satzke, Catherine; Seduadua, Anna; Chandra, Reginald; Carapetis, Jonathan R.; Mulholland, E. Kim; Russell, Fiona M.

    2010-01-01

    The use of Mueller-Hinton agar supplemented with citrated human or citrated sheep blood was compared with the use of routinely used Mueller-Hinton agar supplemented with defibrinated sheep blood for antimicrobial susceptibility testing of Streptococcus pneumoniae. The alternate supplements were found to be unsatisfactory, particularly for testing resistant isolates, and therefore are not recommended. PMID:20668133

  13. Cell-on-hydrogel platform made of agar and alginate for rapid, low-cost, multidimensional test of antimicrobial susceptibility.

    PubMed

    Sun, Han; Liu, Zhengzhi; Hu, Chong; Ren, Kangning

    2016-08-01

    Antimicrobial resistance (AMR) is a rapidly increasing threat to the effective treatment of infectious diseases worldwide. The two major remedies include: (1) using narrow-spectrum antibiotics based on rapid diagnosis; and (2) developing new antibiotics. A key part of both remedies is the antimicrobial susceptibility test (AST). However, the current standard ASTs that monitor colony formation are costly and time-consuming and the new strategies proposed are not yet practical to be implemented. Herein, we report a strategy to fabricate whole-hydrogel microfluidic chips using alginate-doped agar. This agar-based microfabrication makes it possible to prepare inexpensive hydrogel devices, and allows a seamless link between microfluidics and conventional agar-based cell culture. Different from common microfluidic systems, in our system the cells are cultured on top of the device, similar to normal agar plate culture; on the other hand, the microfluidic channels inside the hydrogel allow precise generation of linear gradient of drugs, thus giving a better performance than the conventional disk diffusion method. Cells in this system are not exposed to any shear flow, which allows the reliable tracking of individual cells and AST results to be obtained within 2-3 hours. Furthermore, our system could test the synergistic effect of drugs through two-dimensional gradient generation. Finally, the platform could be directly implemented to new drug discovery and other applications wherein a fast, cost-efficient method for studying the response of microorganisms upon drug administration is desirable. PMID:27452345

  14. Evaluation of an Automated System for Reading and Interpreting Disk Diffusion Antimicrobial Susceptibility Testing of Fastidious Bacteria.

    PubMed

    Idelevich, Evgeny A; Becker, Karsten; Schmitz, Janne; Knaack, Dennis; Peters, Georg; Köck, Robin

    2016-01-01

    Results of disk diffusion antimicrobial susceptibility testing depend on individual visual reading of inhibition zone diameters. Therefore, automated reading using camera systems might represent a useful tool for standardization. In this study, the ADAGIO automated system (Bio-Rad) was evaluated for reading disk diffusion tests of fastidious bacteria. 144 clinical isolates (68 β-haemolytic streptococci, 28 Streptococcus pneumoniae, 18 viridans group streptococci, 13 Haemophilus influenzae, 7 Moraxella catarrhalis, and 10 Campylobacter jejuni) were tested on Mueller-Hinton agar supplemented with 5% defibrinated horse blood and 20 mg/L β-NAD (MH-F, Oxoid) according to EUCAST. Plates were read manually with a ruler and automatically using the ADAGIO system. Inhibition zone diameters, indicated by the automated system, were visually controlled and adjusted, if necessary. Among 1548 isolate-antibiotic combinations, comparison of automated vs. manual reading yielded categorical agreement (CA) without visual adjustment of the automatically determined zone diameters in 81.4%. In 20% (309 of 1548) of tests it was deemed necessary to adjust the automatically determined zone diameter after visual control. After adjustment, CA was 94.8%; very major errors (false susceptible interpretation), major errors (false resistant interpretation) and minor errors (false categorization involving intermediate result), calculated according to the ISO 20776-2 guideline, accounted to 13.7% (13 of 95 resistant results), 3.3% (47 of 1424 susceptible results) and 1.4% (21 of 1548 total results), respectively, compared to manual reading. The ADAGIO system allowed for automated reading of disk diffusion testing in fastidious bacteria and, after visual validation of the automated results, yielded good categorical agreement with manual reading. PMID:27391898

  15. Evaluation of an Automated System for Reading and Interpreting Disk Diffusion Antimicrobial Susceptibility Testing of Fastidious Bacteria

    PubMed Central

    Idelevich, Evgeny A.; Becker, Karsten; Schmitz, Janne; Knaack, Dennis; Peters, Georg; Köck, Robin

    2016-01-01

    Results of disk diffusion antimicrobial susceptibility testing depend on individual visual reading of inhibition zone diameters. Therefore, automated reading using camera systems might represent a useful tool for standardization. In this study, the ADAGIO automated system (Bio-Rad) was evaluated for reading disk diffusion tests of fastidious bacteria. 144 clinical isolates (68 β-haemolytic streptococci, 28 Streptococcus pneumoniae, 18 viridans group streptococci, 13 Haemophilus influenzae, 7 Moraxella catarrhalis, and 10 Campylobacter jejuni) were tested on Mueller-Hinton agar supplemented with 5% defibrinated horse blood and 20 mg/L β-NAD (MH-F, Oxoid) according to EUCAST. Plates were read manually with a ruler and automatically using the ADAGIO system. Inhibition zone diameters, indicated by the automated system, were visually controlled and adjusted, if necessary. Among 1548 isolate-antibiotic combinations, comparison of automated vs. manual reading yielded categorical agreement (CA) without visual adjustment of the automatically determined zone diameters in 81.4%. In 20% (309 of 1548) of tests it was deemed necessary to adjust the automatically determined zone diameter after visual control. After adjustment, CA was 94.8%; very major errors (false susceptible interpretation), major errors (false resistant interpretation) and minor errors (false categorization involving intermediate result), calculated according to the ISO 20776–2 guideline, accounted to 13.7% (13 of 95 resistant results), 3.3% (47 of 1424 susceptible results) and 1.4% (21 of 1548 total results), respectively, compared to manual reading. The ADAGIO system allowed for automated reading of disk diffusion testing in fastidious bacteria and, after visual validation of the automated results, yielded good categorical agreement with manual reading. PMID:27391898

  16. Knowledge and practices of laboratory workers on standardized antimicrobial susceptibility testing and biosafety practices to prevent the spread of superbugs in Pakistan.

    PubMed

    Ghanchi, Najia K; Khan, Erum; Farooqi, Joveria Q; Fasih, Naima; Dojki, Maqboola; Hughes, Molly A

    2014-09-01

    A cross-sectional survey using structured questionnaire was conducted to assess practices of microbiological laboratories working with pathogens. Forty-eight laboratory workers (50%) agreed that laboratory methods to detect antimicrobial resistance are not standardized in Pakistan, and 6% of the laboratory workers were not aware of the standardization of antimicrobial susceptibility testing in Pakistan. Reported rates of awareness regarding the role of waste disposal, disinfection, and handwashing in limiting the spread of antimicrobial resistance were 75%, 42%, and 81%, respectively. Our results provide baseline data for planning programs to train, supervise, and improve the operational quality of microbiological laboratories nationwide to prevent the spread of superbugs. PMID:25179341

  17. Comparative antimicrobial susceptibility of Listeria monocytogenes, L. innocua, and L. welshimeri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current study compared antimicrobial susceptibility of Listeria innocua, L. welshimeri and L. monocytogenes isolated from various sources. Antimicrobial susceptibility testing was performed using a microbroth procedure with Sensititre® minimum inhibitory concentration (MIC) plates containing 18...

  18. In vitro antimicrobial susceptibility testing of Borrelia burgdorferi: a microdilution MIC method and time-kill studies.

    PubMed Central

    Dever, L L; Jorgensen, J H; Barbour, A G

    1992-01-01

    The susceptibility of Borrelia burgdorferi, the causative agent of Lyme borreliosis, to various antimicrobial agents varies widely among published studies. These differences are probably due in part to variations in susceptibility testing techniques and growth endpoint determinations. We developed a microdilution method for determining the MICs of antibiotics against B. burgdorferi. The method incorporated BSK II medium, a final inoculum of 10(6) cells per ml, and a 72-h incubation period and was found to be simple and highly reproducible. A variety of antibiotics and strains of B. burgdorferi and one strain of Borrelia hermsii were examined by this method. MICs of penicillin, ceftriaxone, and erythromycin for the B31 strain of B. burgdorferi were 0.06, 0.03, and 0.03 microgram/ml, respectively. We compared the MICs obtained by the microdilution method with those obtained by a macrodilution method using similar criteria for endpoint determinations and found the values obtained by both methods to be in close agreement. To further investigate the bactericidal activities of penicillin, ceftriaxone, and erythromycin against strain B31, we used subsurface plating to determine MBCs and we also performed time-kill studies. The MBCs of penicillin, ceftriaxone, and erythromycin were 0.125, 0.03, and 0.06 micrograms/ml, respectively. Time-kill curves demonstrated a greater than or equal to 3-log10-unit killing after 72 h with penicillin, ceftriaxone, and erythromycin; ceftriaxone provided the greatest reduction in CFU. The described methods offer a more standardized and objective approach to susceptibility testing of B. burgdorferi. Images PMID:1400969

  19. Evaluation of the automated system Vitek2 for identification and antimicrobial susceptibility testing of Brazilian Gram-positive cocci strains.

    PubMed

    d'Azevedo, Pedro Alves; Siquiera, Itacy; Gugel, Juliana; Antunes, Ana Lúcia Souza; Secchi, Carina; Pasternak, Jacyr; Martino, Marinês Dalla Vale

    2009-04-01

    Automated instruments offer many advantages for clinical laboratories. Nevertheless, they can have problems identifying and determining susceptibilities of some pathogens. Vitek2 (bioMérieux) is an automated system that was recently introduced to Brazil. We evaluated the performance of this equipment for Brazilian isolates that had been characterized using reference identification and antimicrobial susceptibility testing methods. Ninety-nine strains of Gram-positive cocci from a local reference center collection were analyzed, consisting of 50 coagulase-negative Staphylococcus (CoNS) and 49 Enterococcus and related species. Vitek2 correctly identified 79.8% (79/99) of the isolates. Oxacillin resistance was detected in 76% (19/25) of resistant S. epidermidis strains and in 88% (22/25) of other resistant CoNS species strains. Vancomycin resistance was detected in 100% (20/20) of resistant Enterococcus and related species strains. Vitek2 performed very well for the identification of S. epidermidis and non-epidermidis staphylococci, and for the detection of vancomycin resistance in Enterococcus and related species. However, the system needs improvement in order to provide reliable results for the characterization of some CoNS species, identification of Enterococcus and related species and for detecting oxacillin resistance in CoNS. PMID:20140353

  20. Antimicrobial susceptibility among important pathogens collected as part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) in Spain, 2004-2014.

    PubMed

    Marco, Francesc; Dowzicky, Michael J

    2016-09-01

    Here we report in vitro activity data from the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) for tigecycline and comparators against Gram-positive and Gram-negative organisms collected from 27 medical centres in Spain between 2004 and 2014. Minimum inhibitory concentrations (MICs) were determined according to the broth microdilution methodology of the Clinical and Laboratory Standards Institute (CLSI) and susceptibility were determined according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretive criteria. Susceptibility was >97% for all antimicrobials tested against Enterococcus faecalis, and >98% of Enterococcus faecium tested were susceptible to tigecycline, linezolid and vancomycin. A total of 34.1% (1071/3143) of Staphylococcus aureus were meticillin-resistant S. aureus (MRSA), and all MRSA were susceptible to tigecycline and vancomycin. Among the Streptococcus pneumoniae, 5.2% (74/1430) were penicillin-resistant and all isolates were susceptible to linezolid and vancomycin. Among the Enterobacteriaceae, 17.1% (542/3167) of Escherichia coli, 2.8% (19/682) of Klebsiella oxytoca and 19.0% (441/2327) of Klebsiella pneumoniae isolates produced extend-spectrum β-lactamases (ESBLs). Against ESBL-producing E. coli and K. pneumoniae, susceptibility was highest for meropenem, amikacin and tigecycline with rates of >92% and >80%, respectively. Among the Acinetobacter baumannii, susceptibility ranged between 23.5% for levofloxacin and 51.4% for amikacin, and an MIC90 of 2mg/L was observed for tigecycline. In conclusion, monitoring of antimicrobial susceptibility among organisms such as S. aureus, Enterobacteriaceae and A. baumannii is of continuing importance as a guide to clinicians. Depending on the organism to be treated, carbapenems, linezolid, vancomycin and tigecycline continue to be active in Spain. PMID:27530839

  1. In vitro antimicrobial activity of benzoyl peroxide against Propionibacterium acnes assessed by a novel susceptibility testing method.

    PubMed

    Okamoto, Kazuaki; Ikeda, Fumiaki; Kanayama, Shoji; Nakajima, Akiko; Matsumoto, Tatsumi; Ishii, Ritsuko; Umehara, Masatoshi; Gotoh, Naomasa; Hayashi, Naoki; Iyoda, Takako; Matsuzaki, Kaoru; Matsumoto, Satoru; Kawashima, Makoto

    2016-06-01

    Benzoyl peroxide (BPO), a therapeutic agent for acne vulgaris, was assessed for in vitro antimicrobial activity against Propionibacterium acnes using a novel broth microdilution testing that improved BPO solubility. We searched for a suitable culture medium to measure the minimum inhibitory concentration (MIC) of BPO against P. acnes and finally found the Gifu anaerobic medium (GAM) broth supplemented with 0.1(v/v)% glycerol and 2(v/v)% Tween 80, in which BPO dissolved up to 1250 μg/mL and P. acnes grew well. The MICs and minimum bactericidal concentrations (MBCs) of BPO against 44 clinical isolates of P. acnes collected from Japanese patients with acne vulgaris were determined by our testing method using the supplemented GAM broth. The MICs of BPO were 128 or 256 μg/mL against all isolates of P. acnes regardless of susceptibility to nadifloxacin or clindamycin. The MBCs of BPO were also 128 or 256 μg/mL against the same isolates. Moreover, BPO at the MIC showed a rapid bactericidal activity against P. acnes ATCC11827 in time-kill assay. In conclusion, we could develop a novel assay for the MIC and MBC determinations of BPO against P. acnes, which is reliable and reproducible as a broth microdilution testing and the present results suggest that BPO has a potent bactericidal activity against P. acnes. PMID:26806150

  2. Final report from the Committee on Antimicrobial Susceptibility Testing, Japanese Society of Chemotherapy, on the agar dilution method (2007).

    PubMed

    Nagayama, Ariaki; Yamaguchi, Keizo; Watanabe, Kunitomo; Tanaka, Masatoshi; Kobayashi, Intetsu; Nagasawa, Zenzo

    2008-10-01

    In 1968, the agar dilution method was developed as an independent Japanese method for measuring the minimal inhibitory concentration (MIC) of antimicrobial agents. As this method differed in a few respects from the MIC measurement methods used in other countries, it was revised in 1981, by a committee headed by Susumu Mitsuhashi, and the revised method (Chemotherapy 29:76-79, 1981) has been used since then. In 1979, an agar dilution method for measuring the MIC of anaerobes was developed by a committee chaired by Nozomu Kosakai (Chemotherapy 27:559-561, 1979). In 1990, a committee headed by Sachiko Goto approved a broth microdilution method for nonfastidious bacteria (Chemotherapy 38:102-105, 1990). Later, a committee headed by Atsushi Saito examined media that would be suitable for nonfastidious bacteria and fastidious bacteria, and they endeavored to prepare a broth microdilution method for anaerobic bacteria. In this context, a new broth microdilution method was proposed at the 40th Annual Meeting of the Japanese Society of Chemotherapy (JSC) in Nagoya in 1992, and the proposal was adopted as the standard JSC method after some modification (Chemotherapy 41: 183-189, 1993). The agar dilution method has remained unrevised for approximately 20 years. A proposal to review this method was recently made, and the 2007 Committee on Antimicrobial Susceptibility Testing was formed, comprising the JSC members listed below. Under the auspices of this committee, the method revised in 1981 was reviewed in comparison to the international standard method (Clinical and Laboratory Standards Institute [CLSI] method). PMID:18936894

  3. Same Day Identification and Full Panel Antimicrobial Susceptibility Testing of Bacteria from Positive Blood Culture Bottles Made Possible by a Combined Lysis-Filtration Method with MALDI-TOF VITEK Mass Spectrometry and the VITEK2 System

    PubMed Central

    Machen, Alexandra; Drake, Tim; Wang, Yun F. (Wayne)

    2014-01-01

    Rapid identification and antimicrobial susceptibility testing of microorganisms causing bloodstream infections or sepsis have the potential to improve patient care. This proof-of-principle study evaluates the Lysis-Filtration Method for identification as well as antimicrobial susceptibility testing of bacteria directly from positive blood culture bottles in a clinical setting. A total of 100 non-duplicated positive blood cultures were tested and 1012 microorganism-antimicrobial combinations were assessed. An aliquot of non-charcoal blood culture broth was incubated with lysis buffer briefly before being filtered and washed. Microorganisms recovered from the filter membrane were first identified by using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight VITEK® Mass Spectrometry (VITEK MS). After quick identification from VITEK MS, filtered microorganisms were inoculated to VITEK®2 system for full panel antimicrobial susceptibility testing analysis. Of 100 bottles tested, the VITEK MS resulted in 94.0% correct organism identification to the species level. Compared to the conventional antimicrobial susceptibility testing methods, direct antimicrobial susceptibility testing from VITEK®2 resulted in 93.5% (946/1012) category agreement of antimicrobials tested, with 3.6% (36/1012) minor error, 1.7% (7/1012) major error, and 1.3% (13/1012) very major error of antimicrobials. The average time to identification and antimicrobial susceptibility testing was 11.4 hours by using the Lysis-Filtration method for both VITEK MS and VITEK®2 compared to 56.3 hours by using conventional methods (p<0.00001). Thus, the same-day results of microorganism identification and antimicrobial susceptibility testing directly from positive blood culture can be achieved and can be used for appropriate antibiotic therapy and antibiotic stewardship. PMID:24551067

  4. Same day identification and full panel antimicrobial susceptibility testing of bacteria from positive blood culture bottles made possible by a combined lysis-filtration method with MALDI-TOF VITEK mass spectrometry and the VITEK2 system.

    PubMed

    Machen, Alexandra; Drake, Tim; Wang, Yun F Wayne

    2014-01-01

    Rapid identification and antimicrobial susceptibility testing of microorganisms causing bloodstream infections or sepsis have the potential to improve patient care. This proof-of-principle study evaluates the Lysis-Filtration Method for identification as well as antimicrobial susceptibility testing of bacteria directly from positive blood culture bottles in a clinical setting. A total of 100 non-duplicated positive blood cultures were tested and 1012 microorganism-antimicrobial combinations were assessed. An aliquot of non-charcoal blood culture broth was incubated with lysis buffer briefly before being filtered and washed. Microorganisms recovered from the filter membrane were first identified by using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight VITEK® Mass Spectrometry (VITEK MS). After quick identification from VITEK MS, filtered microorganisms were inoculated to VITEK®2 system for full panel antimicrobial susceptibility testing analysis. Of 100 bottles tested, the VITEK MS resulted in 94.0% correct organism identification to the species level. Compared to the conventional antimicrobial susceptibility testing methods, direct antimicrobial susceptibility testing from VITEK®2 resulted in 93.5% (946/1012) category agreement of antimicrobials tested, with 3.6% (36/1012) minor error, 1.7% (7/1012) major error, and 1.3% (13/1012) very major error of antimicrobials. The average time to identification and antimicrobial susceptibility testing was 11.4 hours by using the Lysis-Filtration method for both VITEK MS and VITEK®2 compared to 56.3 hours by using conventional methods (p<0.00001). Thus, the same-day results of microorganism identification and antimicrobial susceptibility testing directly from positive blood culture can be achieved and can be used for appropriate antibiotic therapy and antibiotic stewardship. PMID:24551067

  5. Evaluation of the BD Phoenix Automated Microbiology System for Identification and Antimicrobial Susceptibility Testing of Staphylococci and Enterococci

    PubMed Central

    Carroll, Karen C.; Borek, Anita P.; Burger, Chad; Glanz, Brian; Bhally, Hasan; Henciak, Susan; Flayhart, Diane C.

    2006-01-01

    We evaluated the Phoenix automated microbiology system (BD Diagnostic Systems, Sparks, MD) for the identification (ID) and antimicrobial susceptibility testing (AST) of challenge and clinical staphylococci and enterococci recovered from patients in a tertiary-care medical center. In total, 424 isolates were tested: 90 enterococci; 232 Staphylococcus aureus isolates, including 14 vancomycin-intermediate S. aureus isolates; and 102 staphylococci other than S. aureus (non-S. aureus). The Phoenix panels were inoculated according to the manufacturer's instructions. The reference methods for ID comparisons were conventional biochemicals and cell wall fatty acid analysis with the Sherlock microbial identification system (v 3.1; MIDI, Inc. Newark, DE). Agar dilution was the reference AST method. The overall rates of agreement for identification to the genus and the species levels were 99.7% and 99.3%, respectively. All S. aureus isolates and enterococci were correctly identified by the Phoenix panels. For the non-S. aureus staphylococci, there was 98.0% agreement for the ID of 16 different species. The AST results were stratified by organism group. For S. aureus, the categorical agreement (CA) and essential agreement (EA) were 98.2% and 98.8%, respectively. Three of three very major errors (VMEs; 1.7%) were with oxacillin. For non-S. aureus staphylococci, the CA, EA, VME, major errors, and minor error rates were 95.7%, 96.8%, 0.7%, 1.7%, and 2.9%, respectively. The two VMEs were with oxacillin. For the enterococci, there was 100% CA and 99.3% EA. All 36 vancomycin-resistant enterococci were detected by the Phoenix system. The Phoenix system compares favorably to traditional methods for the ID and AST of staphylococci and enterococci. PMID:16757600

  6. Antimicrobial susceptibility testing of two Lawsonia intracellularis isolates associated with proliferative hemorrhagic enteropathy and porcine intestinal adenomatosis in South Korea.

    PubMed

    Yeh, Jung-Yong; Lee, Ji-Hye; Yeh, Hye-Ryun; Kim, Aeran; Lee, Ji Youn; Hwang, Jeong-Min; Kang, Bo-Kyu; Kim, Jong-Man; Choi, In-Soo; Lee, Joong-Bok

    2011-09-01

    This study represents the first published data on antimicrobial susceptibility of Asian isolates of Lawsonia intracellularis. We assessed MICs of 16 antimicrobials for two isolates of L. intracellularis recovered from diseased pigs in South Korea, one from a finisher pig with acute proliferative hemorrhagic enteropathy in 2002 and the other from a grower pig with porcine intestinal adenomatosis in 2010. Tylosin and tilmicosin were found to be the most active against L. intracellularis both intracellularly (MICs, 0.25 to 0.5 μg/ml and 0.125 μg/ml, respectively) and extracellularly (MICs, 0.25 to 0.5 μg/ml and 1 μg/ml, respectively). PMID:21690283

  7. Clinical Impact of MALDI-TOF MS Identification and Rapid Susceptibility Testing on Adequate Antimicrobial Treatment in Sepsis with Positive Blood Cultures

    PubMed Central

    Verroken, Alexia; Defourny, Lydwine; le Polain de Waroux, Olivier; Belkhir, Leïla; Laterre, Pierre-François; Delmée, Michel; Glupczynski, Youri

    2016-01-01

    Shortening the turn-around time (TAT) of positive blood culture (BC) identification (ID) and susceptibility results is essential to optimize antimicrobial treatment in patients with sepsis. We aimed to evaluate the impact on antimicrobial prescription of a modified workflow of positive BCs providing ID and partial susceptibility results for Enterobacteriaceae (EB), Pseudomonas aeruginosa and Staphylococcus aureus on the day of BC positivity detection. This study was divided into a pre-intervention period (P0) with a standard BC workflow followed by 2 intervention periods (P1, P2) with an identical modified workflow. ID was performed with MALDI-TOF MS from blood, on early or on overnight subcultures. According to ID results, rapid phenotypic assays were realized to detect third generation cephalosporin resistant EB/P. aeruginosa or methicillin resistant S. aureus. Results were transmitted to the antimicrobial stewardship team for patient’s treatment revision. Times to ID, to susceptibility results and to optimal antimicrobial treatment (OAT) were compared across the three study periods. Overall, 134, 112 and 154 positive BC episodes in P0, P1 and P2 respectively were included in the analysis. Mean time to ID (28.3 hours in P0) was reduced by 65.3% in P1 (10.2 hours) and 61.8% in P2 (10.8 hours). Mean time to complete susceptibility results was reduced by 27.5% in P1 and 27% in P2, with results obtained after 32.4 and 32.6 hours compared to 44.7 hours in P0. Rapid tests allowed partial susceptibility results to be obtained after a mean time of 11.8 hours in P1 and 11.7 hours in P2. Mean time to OAT was decreased to 21.6 hours in P1 and to 17.9 hours in P2 compared to 36.1 hours in P0. Reducing TAT of positive BC with MALDI-TOF MS ID and rapid susceptibility testing accelerated prescription of targeted antimicrobial treatment thereby potentially improving the patients’ clinical outcome. PMID:27228001

  8. Antimicrobial susceptibility pattern of Helicobacter suis strains.

    PubMed

    Vermoote, Miet; Pasmans, Frank; Flahou, Bram; Van Deun, Kim; Ducatelle, Richard; Haesebrouck, Freddy

    2011-12-15

    Helicobacter suis is a very fastidious porcine gastric pathogen, which is also considered to be of zoonotic importance. In vitro antimicrobial susceptibility cannot be determined using standard assays, as this agent only grows in a biphasic medium with an acidic pH. Therefore, a combined agar and broth dilution method was used to analyse the activity of nine antimicrobial agents against nine H. suis isolates. After 48 h microaerobic incubation, minimal inhibitory concentrations (MICs) were determined by software-assisted calculation of bacterial growth. Only for enrofloxacin a bimodal distribution of MICs was demonstrated, indicating acquired resistance in one strain, which showed an AGT→AGG (Ser→Arg) substitution at codon 99 of gyrA. In conclusion, the assay developed here is suitable for determination of the antimicrobial susceptibility of H. suis isolates, although activity of acid sensitive antimicrobial agents may be higher than predicted from MIC endpoints. PMID:21733643

  9. Antimicrobial Susceptibility/Resistance of Streptococcus Pneumoniae

    PubMed Central

    Karcic, Emina; Aljicevic, Mufida; Bektas, Sabaheta; Karcic, Bekir

    2015-01-01

    Introduction: Pneumococcal infections are a major cause of morbidity and mortality worldwide, whose treatment is threatened with an increase in the number of strains resistant to antibiotic therapy. Goal: The main goal of this research was to investigate the presence of antimicrobial susceptibility/resistance of S. pneumoniae. Material and methods: Taken are swabs of the nose and nasopharynx, eye and ear. In vitro tests that were made in order to study the antimicrobial resistance of pneumococci are: disk diffusion method and E-test. Results: The resistance to inhibitors of cell wall synthesis was recorded at 39.17%, protein synthesis inhibitors 19.67%, folate antagonists 47.78% and quinolone in 1.11%. S. pneumoniae has shown drug resistance to erythromycin in 45%, clindamycin in 45%, chloramphenicol–0.56%, rifampicin–6.11%, tetracycline–4.67%, penicillin-G in 4.44%, oxacillin in 73.89%, ciprofloxacin in 1.11% and trimethoprim-sulfamethoxazole in 5.34% of cases. Conclusion: The highest resistance pneumococcus showed to erythromycin, clindamycin and trimethoprim-sulfamethoxazole and these should be avoided in the treatment. The least resistance pneumococcus showed to tetracycline, rifampicin, chloramphenicol, penicillin-G and ciprofloxacin. PMID:26236165

  10. [Comparison of the antimicrobial susceptibility testing with three automated systems for MRSA, VISA, ESBL-producing Escherichia coli and Klebsiella pneumoniae].

    PubMed

    Kiyosuke, Makiko; Nagasawa, Zenzo; Kusaba, Koji; Masaki, Takayuki; Yoshimura, Hisae; To, Hiromi; Mitsui, Tomoko; Otsubo, Chiasa; Narita, Chika; Morooka, Tsuyoko; Miyamoto, Hiroshi; Nagayama, Ariaki

    2010-01-01

    Some automated systems of the identification and susceptibility for microorganisms are used and prevail in hospital laboratories. One of the most serious problems is to perform accurate susceptibility testing for low-level resistant organisms, while antibiotic resistant microbes are increasing in medical fields. To evaluate automated machines for the susceptibility testing, several antibiotic resistant organisms were examined by plural technicians in some laboratories. Each strain of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycinintermediate S. aureus (VISA), extended-spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae was tested by three automated systems of WalkAway, VITEK2/VITEK2 compact and Phoenix for susceptibility. The results for antibiotics generated by the systems were compared to those generated by reference methods according to CLSI guidelines. The results of WalkAway, VITEK2/VITEK2 compact, and Phoenix demonstrated 92%, 91%, and 96% of reproducibilities, 92%, 94%, and 91% of MIC agreements, 0.5%, 0.8%, and 0.3% of very major error (VME) and 0.3%, 1.4%, and 2.3% of major error (ME), respectively. All automated systems had a high reproducibility even under the performance of plural technicians, although the differences of VMEs and MEs were observed among the systems. From these data, the automated systems for antimicrobial susceptibility testing were more useful for the detection of antibiotic resistant organisms by understanding the characteristics of each system. PMID:21128697

  11. Antimicrobial susceptibility of Brachyspira hyodysenteriae isolated from 21 Polish farms.

    PubMed

    Zmudzki, J; Szczotka, A; Nowak, A; Strzelecka, H; Grzesiak, A; Pejsak, Z

    2012-01-01

    Swine dysentery (SD) is a common disease among pigs worldwide, which contributes to major production losses. Antimicrobial susceptibility testing of B. hyodysenteriae, the etiological agent of SD, is mainly performed by the agar dilution method. This method has certain limitations due to difficulties in interpretation of results. The aim of this study was the analysis of antimicrobial susceptibility of Brachyspira hyodysenteriae (B. hyodysenteriae) Polish field isolates by broth microdilution procedure. The study was performed on 21 isolates of B. hyodysenteriae, collected between January 2006 to December 2010 from cases of swine dysentery. VetMIC Brachyspira panels with antimicrobial agents (tiamulin, valnemulin, doxycycline, lincomycin, tylosin and ampicillin) were used for susceptibility testing of B. hyodysenteriae. The minimal inhibitory concentration (MIC) was determined by the broth dilution procedure. The lowest antimicrobial activity was demonstrated for tylosin and lincomycin, with inhibition of bacterial growth using concentrations > 128 microg/ml and 32 microg/ml, respectively. In the case of doxycycline, the MIC values were < or = 2.0 microg/ml. No decreased susceptibility to tiamulin was found among the Polish isolates and MIC values for this antibiotic did not exceed 1.0 microg/ml. The results of the present study confirmed that Polish B. hyodysenteriae isolates were susceptible to the main antibiotics (tiamulin and valnemulin) used in treatment of swine dysentery. Further studies are necessary to evaluate a possible slow decrease in susceptibility to tiamulin and valnemulin of B. hyodysenteriae strains in Poland. PMID:22844703

  12. Different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae: VITEK2, MicroScan, Etest, disk diffusion, and broth microdilution.

    PubMed

    Lee, Miae; Chung, Hae-Sun

    2015-05-01

    We investigated different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae. A total of 72 Enterobacteriaceae isolates were collected from a clinical microbiology laboratory of a tertiary university hospital, all of which were detected ertapenem resistance by the VITEK2 system. Bacterial identification and antimicrobial susceptibility were determined using the VITEK2. Ertapenem susceptibility test was performed using the MicroScan, Etest and a disk diffusion test. Ertapenem MICs were confirmed using the broth microdilution (BMD). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of each method for the detection of ertapenem resistance were calculated. Carbapenemases and AmpC β-lactamase were screened using phenotypic methods. Among the 72 isolates, 20 isolates (27.8%) were resistant to ertapenem. Etest showed high sensitivity and specificity (85.0% and 88.5%, respectively) and excellent concordance with BMD. The disk diffusion test had the lowest sensitivity of 50.0%. The VITEK2 showed the lowest essential and categorical agreement (30.5% and 27.8%, respectively). The MicroScan showed relatively good agreement with BMD compared to the VITEK2. Most category disagreements were minor errors. There were 3 very major errors in both the MicroScan and disk diffusion test. Only 1 isolate was positive for carbapenemase screening test and all of the isolates were positive for AmpC screening test. In conclusion, the detection of ertapenem resistance in Enterobacteriaceae has limitations using routine testing such as an automated system or disk diffusion. Confirmation of results by an additional MIC test is recommended for accurate resistance results of ertapenem. PMID:25794901

  13. Investigation of Clostridium difficile interspecies relatedness using multilocus sequence typing, multilocus variable-number tandem-repeat analysis and antimicrobial susceptibility testing.

    PubMed

    Rodriguez, C; Avesani, V; Taminiau, B; Van Broeck, J; Brévers, B; Delmée, M; Daube, G

    2015-12-01

    Multilocus sequence typing (MLST), multilocus variable-number tandem-repeat analysis (MLVA) and antimicrobial susceptibility were performed on 37 animal and human C. difficile isolates belonging to 15 different PCR-ribotypes in order to investigate the relatedness of human and animal isolates and to identify possible transmission routes. MLVA identified a total of 21 different types while MLST only distinguished 12 types. Identical C. difficile strains were detected in the same animal species for PCR-ribotypes 014, 078, UCL 16U and UCL 36, irrespective of their origin or the isolation date. Non clonal strains were found among different hosts; however, a high genetic association between pig and cattle isolates belonging to PCR-ribotype 078 was revealed. MLVA also showed genetic differences that clearly distinguished human from animal strains. For a given PCR-ribotype, human and animal strains presented a similar susceptibility to the antimicrobials tested. All strains were susceptible to vancomycin, metronidazole, chloramphenicol and rifampicin, while PCR-ribotypes 078, UCL 5a, UCL 36 and UCL 103 were associated with erythromycin resistance. The data suggest a wide dissemination of clones at hospitals and breeding-farms or a contamination at the slaughterhouse, but less probability of interspecies transmission. However, further highly discriminatory genotyping methods are necessary to elucidate interspecies and zoonotic transmission of C. difficile. PMID:26545846

  14. [First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans/ Anaerobic Subcommittee of the Asociación Argentina de Microbiología].

    PubMed

    Legaria, María C; Bianchini, Hebe M; Castello, Liliana; Carloni, Graciela; Di Martino, Ana; Fernández Canigia, Liliana; Litterio, Mirta; Rollet, Raquel; Rossetti, Adelaida; Predari, Silvia C

    2011-01-01

    Through time, anaerobic bacteria have shown good susceptibility to clinically useful antianaerobic agents. Nevertheless, the antimicrobial resistance profile of most of the anaerobic species related to severe infections in humans has been modified in the last years and different kinds of resistance to the most active agents have emerged, making their effectiveness less predictable. With the aim of finding an answer and for the purpose of facilitating the detection of anaerobic antimicrobial resistance, the Anaerobic Subcommittee of the Asociación Argentina de Microbiología developed the First Argentine consensus guidelines for in vitro antimicrobial susceptibility testing of clinically relevant anaerobic bacteria in humans. This document resulted from the compatibilization of the Clinical and Laboratory Standards Institute recommendations, the international literature and the work and experience of the Subcommittee. The Consensus document provides a brief taxonomy review, and exposes why and when anaerobic antimicrobial susceptibility tests should be conducted, and which antimicrobial agents can be used according to the species involved. The recommendations on how to perform, read and interpret in vitro anaerobic antimicrobial susceptibility tests with each method are exposed. Finally, the antibiotic susceptibility profile, the classification of antibiotics according to their in vitro activities, the natural and acquired mechanisms of resistance, the emerging resistance and the regional antibiotic resistance profile of clinically relevant anaerobic species are shown. PMID:21491069

  15. [Susceptibilities of clinical bacterial isolates to antimicrobial agents. A study mainly focused on imipenem. Reported by the Research Group for Testing Imipenem Susceptibility on Clinical Isolates].

    PubMed

    Igari, J

    1990-11-01

    This study was conducted to investigate susceptibilities of clinical bacterial isolates to imipenem (IPM) and other antibacterial agents at 64 hospital laboratories throughout Japan from September to December of 1988. In this study, identification and susceptibility testing were carried out at each laboratory and the tests were performed according to the disk dilution method recommended by NCCLS in which susceptibilities are classified into "S", "MS", "I" and "R". IPM showed markedly high in vitro activities against Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus faecalis, Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae, Serratia marcescens, Salmonella spp., Citrobacter freundii, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Providencia rettgeri, Providencia stuartii, Acinetobacter calcoaceticus, Moraxella (Branhamella) catarrhalis, Alcaligenes spp., Peptococcus spp./Peptostreptococcus spp., Bacteroides fragilis and Bacteroides spp. IPM also had strong activities against Achromobacter xylosoxidans and Pseudomonas aeruginosa, but less active against Flavobacterium spp., E. faecium, coagulase-negative staphylococci (CNS), Staphylococcus aureus and Pseudomonas cepacia. In a study in which activities of IPM against bacteria isolated from different clinical sources were compared, differences in susceptibilities were observed among S. aureus, CNS, A. calcoaceticus and P. aeruginosa, but such differences were not apparent among S. pneumoniae, E. faecalis, H. influenzae, E. coli, K. pneumoniae, E. cloacae, C. freundii, S. marcescens or P. mirabilis. PMID:2287060

  16. Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data – The Influence of Different Parameters in a Routine Clinical Microbiology Laboratory

    PubMed Central

    Kohlmann, Rebekka; Gatermann, Sören G.

    2016-01-01

    Introduction Many clinical microbiology laboratories report on cumulative antimicrobial susceptibility testing (cAST) data on a regular basis. Criteria for generation of cAST reports, however, are often obscure and inconsistent. Whereas the CLSI has published a guideline for analysis and presentation of cAST data, national guidelines directed at clinical microbiology laboratories are not available in Europe. Thus, we sought to describe the influence of different parameters in the process of cAST data analysis in the setting of a German routine clinical microbiology laboratory during 2 consecutive years. Material and Methods We developed various program scripts to assess the consequences ensuing from different algorithms for calculation of cumulative antibiograms from the data collected in our clinical microbiology laboratory in 2013 and 2014. Results One of the most pronounced effects was caused by exclusion of screening cultures for multi-drug resistant organisms which decreased the MRSA rate in some cases to one third. Dependent on the handling of duplicate isolates, i.e. isolates of the same species recovered from successive cultures on the same patient during the time period analyzed, we recorded differences in resistance rates of up to 5 percentage points for S. aureus, E. coli and K. pneumoniae and up to 10 percentage points for P. aeruginosa. Stratification by site of care and specimen type, testing of antimicrobials selectively on resistant isolates, change of interpretation rules and analysis at genus level instead of species level resulted in further changes of calculated antimicrobial resistance rates. Conclusion The choice of parameters for cAST data analysis may have a substantial influence on calculated antimicrobial resistance rates. Consequently, comparability of cAST reports from different clinical microbiology laboratories may be limited. We suggest that laboratories communicate the strategy used for cAST data analysis as long as national

  17. Molecular Characterization and Antimicrobial Susceptibility Testing of Escherichia coli Isolates from Patients with Urinary Tract Infections in 20 Chinese Hospitals▿

    PubMed Central

    Cao, Xiaoli; Cavaco, Lina M.; Lv, Yuan; Li, Yun; Zheng, Bo; Wang, Pengyuan; Hasman, Henrik; Liu, Yucun; Aarestrup, Frank M.

    2011-01-01

    A total of 222 urinary Escherichia coli isolates from 20 tertiary hospitals in 15 different provinces and 4 municipalities in mainland China were characterized by antimicrobial susceptibility, phylogrouping, and the presence of plasmid-mediated quinolone resistance genes. A subset of 138 suspected extended-spectrum cephalosporinase (ESC) producers were examined for genes encoding cephalosporin resistance. Forty-three isolates harboring blaCTX-M-14 or blaCTX-M-15 were analyzed by pulsed-field gel electrophoresis (PFGE), and plasmids containing these genes were typed using PCR-based replicon typing (PBRT). Thirteen phylogroup B2 blaCTX-M-14- and blaCTX-M-15-positive isolates were analyzed by multilocus sequence typing (MLST). A frequent occurrence of resistance (>46%) was observed toward cephalosporins, gentamicin, and fluoroquinolones. Among the 222 isolates, 4 qnrS1, 4 qepA, and 16 aac(6′)-Ib-cr genes were confirmed. Four major phylogroups (A, B1, B2, and D) and nontypeable isolates (NTs) were found among the isolates, with phylogroup D (54%) being the most common phylogroup. A total of 110 (80%) of the 138 screened isolates harbored blaCTX-M genes, with blaCTX-M-14 (71%) and blaCTX-M-15 (24%) being the most prevalent of these genes. Nine of the 13 CTX-M-15- or CTX-M-14-containing B2 isolates belonged to ST131. PFGE typing showed a high level of diversity, and plasmid analysis indicated a very large pool of different resistance plasmids mediating the spread of blaCTX-M genes in mainland China. An equally very high frequency of resistance and equally high levels of diversity in phylogroups, PFGE types, and plasmids were observed among community- and hospital-acquired E. coli isolates, indicating the presence of a large reservoir in the community and a long-term spread of cephalosporin resistance in China. PMID:21525216

  18. In Vitro Antimicrobial Susceptibility of Mycobacterium abscessus in Korea

    PubMed Central

    Park, Sunghoon; Kim, Shinok; Park, Eun Mi; Kim, Hojoong; Kwon, O Jung; Chang, Chulhun L.; Lew, Woo Jin; Park, Young Kil

    2008-01-01

    Mycobacterium abscessus is the second most common etiology of pulmonary disease caused by nontuberculous mycobacteria in Korea. Although antimicrobial susceptibility tests are important for appropriate patient management in M. abscessus lung disease, the tests have never been investigated in Korea. Seventy-four isolates of M. abscessus recovered from patient respiratory samples were tested against eight antimicrobial agents following the guidelines set forth by the National Committee for Clinical Laboratory Standards. Of the parenteral antibiotics, amikacin (99%, 73/74) and cefoxitin (99%, 73/74) were active against most isolates. Imipenem (55%, 36/66) and tobramycin (36%, 27/74) had activity against moderate number of isolates. Of the oral antibiotics, clarithromycin (91%, 67/74) was active against the majority of isolates. Moxifloxacin (73%, 54/74) and ciprofloxacin (57%, 42/74) had activity against a moderate number of isolates. Doxycycline was the least active, inhibiting only 7% (5/74) of isolates. In conclusion, the variations in susceptibility within M. abscessus isolates to currently available antimicrobials suggest that the antimicrobial susceptibilities of any clinically significant M. abscessus isolate be needed individually. PMID:18303198

  19. Susceptibility of bifidobacteria of animal origin to selected antimicrobial agents.

    PubMed

    Mayrhofer, Sigrid; Mair, Christiane; Kneifel, Wolfgang; Domig, Konrad J

    2011-01-01

    Strains of the genus Bifidobacterium are frequently used as probiotics, for which the absence of acquired antimicrobial resistance has become an important safety criterion. This clarifies the need for antibiotic susceptibility data for bifidobacteria. Based on a recently published standard for antimicrobial susceptibility testing of bifidobacteria with broth microdilution method, the range of susceptibility to selected antibiotics in 117 animal bifidobacterial strains was examined. Narrow unimodal MIC distributions either situated at the low-end (chloramphenicol, linezolid, and quinupristin/dalfopristin) or high-end (kanamycin, neomycin) concentration range could be detected. In contrast, the MIC distribution of trimethoprim was multimodal. Data derived from this study can be used as a basis for reviewing or verifying present microbiological breakpoints suggested by regulatory agencies to assess the safety of these micro-organisms intended for the use in probiotics. PMID:22312561

  20. Mycobacterium arupense flexor tenosynovitis: case report and review of antimicrobial susceptibility profiles for 40 clinical isolates.

    PubMed

    Beam, Elena; Vasoo, Shawn; Simner, Patricia J; Rizzo, Marco; Mason, Erin L; Walker, Randall C; Deml, Sharon M; Brown-Elliott, Barbara A; Wallace, Richard J; Wengenack, Nancy L; Sia, Irene G

    2014-07-01

    We describe a case of chronic tenosynovitis in the hand of a 58-year-old cattle farmer. Surgical biopsy specimens grew Mycobacterium arupense. The patient responded to surgery and antimicrobial therapy based on in vitro susceptibility testing. The antimicrobial susceptibility profiles of the isolate from this patient and 39 additional clinical isolates are presented. PMID:24789193

  1. Antimicrobial Activity of Ceftaroline Tested against Staphylococci with Reduced Susceptibility to Linezolid, Daptomycin, or Vancomycin from U.S. Hospitals, 2008 to 2011

    PubMed Central

    Flamm, Robert K.; Jones, Ronald N.

    2013-01-01

    Vancomycin, linezolid, and daptomycin are very active against staphylococci, but isolates with decreased susceptibility to these antimicrobial agents are isolated sporadically. A total of 19,350 Staphylococcus aureus isolates (51% methicillin resistant [MRSA]) and 3,270 coagulase-negative staphylococci (CoNS) were collected consecutively from 82 U.S. medical centers from January 2008 to December 2011 and tested for susceptibility against ceftaroline and comparator agents by the reference broth microdilution method. Among S. aureus strains, 14 isolates (0.07%) exhibited decreased susceptibility to linezolid (MIC, ≥8 μg/ml), 18 (0.09%) to daptomycin (MIC, ≥2 μg/ml), and 369 (1.9%) to vancomycin (MIC, ≥2 μg/ml; 368 isolates at 2 μg/ml and 1 at 4 μg/ml). Fifty-one (1.6%) CoNS were linezolid resistant (MIC, ≥8 μg/ml), and four (0.12%) were daptomycin nonsusceptible (MIC, ≥2 μg/ml). Ceftaroline was very active against S. aureus overall (MIC50/90, 0.5/1 μg/ml; 98.5% susceptible), including MRSA (MIC50/90, 0.5/1 μg/ml; 97.2% susceptible). All daptomycin-nonsusceptible and 85.7% of linezolid-resistant S. aureus isolates were susceptible to ceftaroline. Against S. aureus isolates with a vancomycin MIC of ≥2 μg/ml, 91.9, 96.2, and 98.9% were susceptible to ceftaroline, daptomycin, and linezolid, respectively. CoNS strains were susceptible to ceftaroline (MIC50/90, 0.25/0.5 μg/ml; 99.1% inhibited at ≤1 μg/ml), including methicillin-resistant (MIC50/90, 0.25/0.5 μg/ml), linezolid-resistant (MIC50/90, 0.5/0.5 μg/ml), and daptomycin-nonsusceptible (4 isolates; MIC range, 0.03 to 0.12 μg/ml) strains. In conclusion, ceftaroline demonstrated potent in vitro activity against staphylococci with reduced susceptibility to linezolid, daptomycin, or vancomycin, and it may represent a valuable treatment option for infections caused by these multidrug-resistant staphylococci. PMID:23629712

  2. A Novel 7-Single Nucleotide Polymorphism-Based Clonotyping Test Allows Rapid Prediction of Antimicrobial Susceptibility of Extraintestinal Escherichia coli Directly From Urine Specimens

    PubMed Central

    Tchesnokova, Veronika; Avagyan, Hovhannes; Billig, Mariya; Chattopadhyay, Sujay; Aprikian, Pavel; Chan, Diana; Pseunova, Julietta; Rechkina, Elena; Riddell, Kim; Scholes, Delia; Fang, Ferric C.; Johnson, James R.; Sokurenko, Evgeni V.

    2016-01-01

    Background. Escherichia coli is a highly clonal pathogen. Extraintestinal isolates belong to a limited number of genetically related groups, which often exhibit characteristic antimicrobial resistance profiles. Methods. We developed a rapid clonotyping method for extraintestinal E coli based on detection of the presence or absence of 7 single nucleotide polymorphisms (SNPs) within 2 genes (fumC and fimH). A reference set of 2559 E coli isolates, primarily of urinary origin, was used to predict the resolving power of the 7-SNP-based typing method, and 582 representative strains from this set were used to evaluate test robustness. Results. Fifty-four unique SNP combinations (“septatypes”) were identified in the reference strains. These septatypes yielded a clonal group resolution power on par with that of traditional multilocus sequence typing. In 72% of isolates, septatype identity predicted sequence type identity with at least 90% (mean, 97%) accuracy. Most septatypes exhibited highly distinctive antimicrobial susceptibility profiles. The 7-SNP-based test could be performed with high specificity and sensitivity using single or multiplex conventional polymerase chain reaction (PCR) and quantitative PCR. In the latter format, E coli presence and septatype identity were determined directly in urine specimens within 45 minutes with bacterial loads as low as 102 colony-forming units/mL and, at clinically significant bacterial loads, with 100% sensitivity and specificity. Conclusions. 7-SNP-based typing of E coli can be used for both epidemiological studies and clinical diagnostics, which could greatly improve the empirical selection of antimicrobial therapy. PMID:26925427

  3. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    PubMed Central

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  4. Antimicrobial susceptibility of potentially pathogenic halophilic vibrios isolated from seafood.

    PubMed

    Ottaviani, D; Bacchiocchi, I; Masini, L; Leoni, F; Carraturo, A; Giammarioli, M; Sbaraglia, G

    2001-08-01

    Susceptibility patterns to 27 antimicrobial agents and beta-lactamase production were investigated in potentially pathogenic halophilic vibrios from seafood. The effect of salinity on the response to the drugs in vitro was also studied. All isolates were uniformly sensitive to choramphenicol, imipenem, meropenem but resistant to lincomycin. All were highly sensitive to oxolinic acid, trimethoprim-sulphamethoxazole, doxycycline, flumequine, cefotaxime, nalidixic acid and ciprofloxacin. Some strains of V. harveyi, V. alginolyticus and V. parahaemolyticus apparently had mechanisms of resistance to several beta-lactam antibiotics other than by the production of beta-lactamases. Sixty-nine strains produced penicillinase but a low correlation between beta-lactamase activity and resistance to beta-lactam antibiotics was noted. The salt concentration affected the in vitro susceptibility of halophilic vibrios and the effect of salinity depended on both the individual strains and the antimicrobial tested. PMID:11516936

  5. Antimicrobial susceptibility of equine and environmental isolates of Clostridium difficile.

    PubMed

    Båverud, V; Gunnarsson, A; Karlsson, M; Franklin, A

    2004-01-01

    The antimicrobial susceptibility of 50 Clostridium difficile isolates, 36 of them from horse feces and 14 from environmental sites, was determined by broth microdilution. The antimicrobial agents tested were avilamycin, cephalothin, chloramphenicol, clindamycin, erythromycin, gentamicin, neomycin, oxacillin, oxytetracycline, penicillin, spiramycin, streptomycin, trimethoprim/sulfamethoxazole, vancomycin, and virginiamycin. All isolates were susceptible to vancomycin (MIC 16 microg/ml), oxytetracycline (MIC >/=32 microg/ml), spiramycin (MIC > 16 microg/ml), and virginiamycin (MIC 8-16 microg/ml) were higher for 18 isolates. Those were mainly isolated from horses at animal hospitals and further from environmental sites at a stud farm. In contrast, all isolates, except one, from healthy foals had low MICs of erythromycin, spiramycin, virginiamycin, and oxytetracycline. The isolates from soil in public parks had also low MICs of these antimicrobial agents. Broth microdilution appeared both reliable and reproducible for susceptibility testing of C. difficile. The method was also readily performed and the MIC endpoints were easily read. PMID:15140395

  6. Evaluation of the Dade MicroScan MICroSTREP Antimicrobial Susceptibility Testing Panel with Selected Streptococcus pneumoniae Challenge Strains and Recent Clinical Isolates

    PubMed Central

    Jorgensen, J. H.; McElmeel, M. L.; Crawford, S. A.

    1998-01-01

    The MicroScan MICroSTREP panel is a recently marketed frozen broth microdilution panel for susceptibility testing of various streptococci, including Streptococcus pneumoniae. The panel contains 10 antimicrobial agents in cation-adjusted Mueller-Hinton broth supplemented with 3% lysed horse blood, similar in concept to the National Committee for Clinical Laboratory Standards (NCCLS) reference broth microdilution method for testing streptococci. A group of 210 isolates of S. pneumoniae were selected to include isolates with previously documented resistance to agents incorporated in the MICroSTREP panel, as well as recent invasive clinical isolates. All isolates were tested simultaneously with the MICroSTREP panel and an NCCLS reference panel whose drug concentrations were prepared to coincide with those of the MICroSTREP panel. Of the 210 isolates, 5 failed to grow in the MICroSTREP panel; 3 of those also did not grow in the reference panel. Essential agreement of MICs determined by the two methods (test MIC ± one dilution of the reference MIC) was 99.6% overall and ranged from 98.0% with chloramphenicol to 100% with penicillin, ceftriaxone, erythromycin, tetracycline, and vancomycin. There were no very major or major interpretive category errors resulting from the MICroSTREP panel tests. Minor interpretive category errors ranged from 12.2% with cefotaxime and 9.8% with ceftriaxone (due mainly to clustering of MICs for the selected strains near the breakpoints) to 0% with chloramphenicol and vancomycin. These results indicate that the MicroScan MICroSTREP frozen panels provide susceptibility results with pneumococci that are essentially equivalent to results derived by the NCCLS reference broth microdilution procedure. PMID:9508313

  7. Natural antimicrobial susceptibilities of Plesiomonas shigelloides strains.

    PubMed

    Stock, I; Wiedemann, B

    2001-12-01

    The natural susceptibility of 74 Plesiomonas shigelloides strains isolated from humans (n = 50), water (n = 22) and animals (n = 2) to 71 antibiotics was examined. MICs were performed using a microdilution procedure with Mueller-Hinton broth and an inoculum of 1 x 10(6) cfu/mL. Plesiomonas strains were naturally susceptible or naturally susceptible and intermediate to tetracyclines, several aminoglycosides, aminopenicillins in combination with beta-lactamase inhibitors, all cephalosporins except cefoperazone, ceftazidime and cefepime, carbapenems, aztreonam, quinolones, trimethoprim, sulfamethoxazole, azithromycin, chloramphenicol, nitrofurantoin and fosfomycin. Uniform natural resistance was found to all penicillins tested, roxithromycin, clarithromycin, lincosamides, streptogramins, glycopeptides and fusidic acid. Plesiomonas strains were naturally resistant and intermediate to streptomycin, erythromycin and rifampicin. There were two susceptibility patterns to piperacillin/tazobactam, several cephalosporins and aztreonam. In contrast to a previous study with beta-lactam antibiotics, susceptibility testing of non-beta-lactams revealed no alterations of the MICs of most antibiotics, using different inocula and media. A database is described of the natural susceptibility of P. shigelloides strains to a wide range of antibiotics. It can be used for the validation of susceptibility test results of these bacteria. PMID:11733464

  8. Differences in the antimicrobial susceptibility profiles of Moraxella bovis, M. bovoculi and M. ovis

    PubMed Central

    Maboni, Grazieli; Gressler, Leticia T.; Espindola, Julia P.; Schwab, Marcelo; Tasca, Caiane; Potter, Luciana; de Vargas, Agueda Castagna

    2015-01-01

    The aim of this study was to determine the differences in the antimicrobial susceptibility profiles of Moraxella bovis, M. bovoculi and M. ovis. Thirty-two strains of Moraxella spp. isolated from cattle and sheep with infectious keratoconjunctivitis were tested via broth microdilution method to determine their susceptibility to ampicillin, cefoperazone, ceftiofur, cloxacillin, enrofloxacin, florfenicol, gentamicin, neomycin, oxytetracycline and penicillin. The results demonstrated that Moraxella spp. strains could be considered sensitive for most of the antimicrobials tested in this study, but differences between the antimicrobial susceptibility profiles of these three Moraxella species were found. M. bovis might differ from other species due to the higher MIC and MBC values it presented. PMID:26273272

  9. Antimicrobial susceptibilities of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents.

    PubMed

    Soriano, F; Zapardiel, J; Nieto, E

    1995-01-01

    The susceptibilities of 265 strains of Corynebacterium species and other non-spore-forming gram-positive bacilli to 18 antimicrobial agents were tested. Most strains were susceptible to vancomycin, doxycycline, and fusidic acid. Corynebacterium jeikeium and Corynebacterium urealyticum were the most resistant organisms tested. Resistance to beta-lactams, clindamycin, erythromycin, azythromycin, ciprofloxacin and gentamicin was common among strains of Corynebacterium xerosis and Corynebacterium minutissimum. Ampicillin resistance among Listeria monocytogenes was more prevalent than previously reported. Optochin, fosfomycin, and nitrofurantoin showed very little activity against most organisms tested, but the use of nitrofurantoin as a selective agent in culture medium may prevent the recovery of some isolates. Except for the unvarying activity of vancomycin against Corynebacterium species, the antimicrobial susceptibilities of the latter to other antibiotics are usually unpredictable, such that susceptibility tests are necessary for selecting the best antimicrobial treatment. PMID:7695308

  10. Susceptibility and resistance of ruminal bacteria to antimicrobial feed additives.

    PubMed Central

    Nagaraja, T G; Taylor, M B

    1987-01-01

    Susceptibility and resistance of ruminal bacterial species to avoparcin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, and two new ionophore antibiotics, RO22-6924/004 and RO21-6447/009, were determined. Generally, antimicrobial compounds were inhibitory to gram-positive bacteria and those bacteria that have gram-positive-like cell wall structure. MICs ranged from 0.09 to 24.0 micrograms/ml. Gram-negative bacteria were resistant at the highest concentration tested (48.0 micrograms/ml). On the basis of their fermentation products, ruminal bacteria that produce lactic acid, butyric acid, formic acid, or hydrogen were susceptible and bacteria that produce succinic acid or ferment lactic acid were resistant to the antimicrobial compounds. Selenomonas ruminantium was the only major lactic acid-producing bacteria resistant to all the antimicrobial compounds tested. Avoparcin and tylosin appeared to be less inhibitory (MIC greater than 6.0 micrograms/ml) than the other compounds to the two major lactic acid-producing bacteria, Streptococcus bovis and Lactobacillus sp. Ionophore compounds seemed to be more inhibitory (MIC, 0.09 to 1.50 micrograms/ml) than nonionophore compounds (MIC, 0.75 to 12.0 micrograms/ml) to the major butyric acid-producing bacteria. Treponema bryantii, an anaerobic rumen spirochete, was less sensitive to virginiamycin than to the other antimicrobial compounds. Ionophore compounds were generally bacteriostatic, and nonionophore compounds were bactericidal. The specific growth rate of Bacteroides ruminicola was reduced by all the antimicrobial compounds except avoparcin. The antibacterial spectra of the feed additives were remarkably similar, and it appears that MICs may not be good indicators of the potency of the compounds in altering ruminal fermentation characteristics. PMID:3116929

  11. Antimicrobial susceptibility of Staphylococcus aureus from retail ground meats.

    PubMed

    Kelman, Alina; Soong, Yee-Ann; Dupuy, Nicole; Shafer, Daniel; Richbourg, William; Johnson, Kourtney; Brown, Twain; Kestler, Edward; Li, Yi; Zheng, Jie; McDermott, Patrick; Meng, Jianghong

    2011-10-01

    The aim of this study was to characterize antimicrobial resistance in Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), recovered from raw retail meat products purchased in the Washington, D.C., area. From March to August 2008, 694 samples of ground beef (n = 198), ground pork (n = 300), and ground turkey (n = 196) were collected by random sampling from stores of three grocery chains. In total, 200 S. aureus isolates (29%) were recovered by direct plating. When tested for susceptibility to 22 antimicrobials, 69% of the S. aureus isolates were resistant to tetracycline, 26% to penicillin, 17% to ampicillin, 13% to methicillin, 8% to erythromycin, 4.5% to clindamycin, 1.5% to gentamicin, and 0.5% to chloramphenicol, oxacillin, cefoxitin, or quinupristin-dalfopristin. However, 27% of the isolates were susceptible to all tested antimicrobials. More turkey and pork isolates were resistant to ampicillin, penicillin, and tetracycline than were beef isolates (P < 0.05). Additionally, 17% of the turkey and 17% of the pork isolates were resistant to methicillin (MIC ≥ 16 μg/ml), whereas no beef isolates were resistant to the antimicrobial agent. A single MRSA (methicillin MIC > 32 μg/ml) isolate containing the mecA gene with additional resistance to erythromycin, clindamycin, oxacillin plus 2% NaCl, cefoxitin, ampicillin, penicillin, quinupristin-dalfopristin, tetracycline, and gentamicin was recovered from one pork sample. The presence of antimicrobial-resistant S. aureus, coupled with the relative lack of such studies in the United States, suggests that further investigations on MRSA in the food supply are needed despite the low rate of MRSA found in this particular study. PMID:22004808

  12. Antimicrobial susceptibility and molecular characterization of Mycobacterium intracellulare in China.

    PubMed

    Zhao, Xiuqin; Wang, Yufeng; Pang, Yu

    2014-10-01

    Mycobacterium avium complex (MAC) is the most common non-tuberculosis mycobacterial pathogen isolated from respiratory samples, mainly including two species, Mycobacterium avium (M. avium) and Mycobacterium intracellulare (M. intracellulare). Although these two species belong to the same group, M. avium and M. intracellulare reveal significantly differences in pathogenicity and biology. Nevertheless, little is known regarding the drug resistant details profile of M. avium or M. intracellulare instead of MAC. Here, we examined the antimicrobial susceptibility profiles of 52 clinical M. intracellulare isolates against fourteen antimicrobial agents, which are widely selected for the treatment of nontuberculous mycobacteria (NTM) infection. The drug susceptibility test revealed that clarithromycin (47/52, 90.4%), rifampicin (41/52, 78.8%) and capreomycin (40/52, 76.9%) revealed highly antimicrobial activities against M. intracellulare isolates in vitro. Furthermore, all clarithromycin resistant isolates harbored mutations in the 23S rRNA gene, and the percentage of amikacin resistant ones with mutation in the rrs gene is 62.5% (10/16). The Hunter-Gaston Discriminatory Index (HGDI) value for the 16-loci Variable Number of Tandem Repeat (VNTR) typing of M. intracellulare isolates was 0.994, and M. intracellulare resistance to moxifloxacin was significantly more commonly found in clustered strains than in nonclustered strains (χ(2)=5.551, P=0.040). In conclusion, our data demonstrated that clarithromycin and capreomycin revealed highly antimicrobial activities against M. intracellulare isolates, and clarithromycin and amikacin resistance could be detected more readily and rapidly using molecular scanning of corresponding drug target than conventional drug susceptibility testing. We also found that infection by clustered strains was significantly associated with resistance to moxifloxacin. PMID:25131955

  13. Antimicrobial susceptibility of Leptospira isolates from dogs and rats to 12 antimicrobial agents.

    PubMed

    Suepaul, S M; Carrington, C; Campbell, M; Borde, G; Adesiyun, A A

    2015-03-01

    This study determined the antimicrobial susceptibilities of 67 isolates of Leptospira from dogs (suspect canine cases: n=7 and stray dogs: n=6) and rodents (n=54) in Trinidad to 12 antimicrobial agents using broth microdilution and macrodilution techniques. Commonly used antimicrobial agents such as the penicillin G and ceftriaxone had relatively low minimal inhibitory concentrations (MICs) while doxycycline displayed a relatively higher value but was still considered to be effective. While imipenem was the most effective with low MIC values in vitro, sulphamethoxazole-trimethoprim had the highest i.e. least effective. Based on these results, the drugs commonly used in the treatment of leptospirosis (penicillin G, penicillin-streptomycin, doxycycline and ceftriaxone) in both humans and animals in Trinidad appear to have similar MICs and MBCs in vitro when compared with published reports. The serovar of Leptospira spp. and in most cases the origin of the isolates did not significantly (P>0.05) influence their susceptibilities to the antimicrobial agents tested. PMID:25801249

  14. Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilium to nine antimicrobials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for fish pathogens Flavobacterium columnare and F. pyschrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicid...

  15. Antimicrobial susceptibility among gram-negative isolates collected in the USA between 2005 and 2011 as part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.)

    PubMed Central

    2013-01-01

    Background The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) was designed to monitor in vitro antimicrobial susceptibility to tigecycline and comparator agents. We present susceptibility data on Gram-negative organisms collected between 2005 and 2011 from nine United States census regions. Methods T.E.S.T. was conducted using standardized CLSI methodologies or FDA-approved breakpoints. Results Tigecycline was highly active (MIC90 ≤ 2 mg/L) against Enterobacteriaceae irrespective of species or region of collection (N = 25011). The isolates were also highly susceptible to the carbapenems when all regional data are combined, except for ESBL-producing Klebsiella pneumoniae (MIC90 16 mg/L) and Acinetobacter baumannii (MIC90 ≥ 32 mg/L). In addition, 883 (30%) of 2900 A. baumannii isolates were classified as multidrug-resistant (MDR): these MDR organisms were most susceptible to tigecycline (MIC90 2 mg/L) and minocycline (MIC90 8 mg/L) when all regional data are considered together. Susceptibility patterns also varied widely among the regions Conclusions The findings highlight the importance of monitoring antimicrobial susceptibility patterns and implementing effective methods to curb increased resistance and also confirm that additional studies to determine the efficacy of tigecycline in vivo, especially for treating infections with MDR organisms, are warranted. PMID:24006892

  16. [Proposals of the working group "Antibiotic resistance" for the configuration of microtitre plates to be used in routine antimicrobial susceptibility testing of bacterial pathogens from infections of large food-producing animals and mastitis cases].

    PubMed

    Luhofer, Gabriele; Böttner, Alexander; Hafez, H Mohamed; Kaske, Martin; Kehrenberg, Corinna; Kietzmann, Manfred; Klarmann, Dieter; Klein, Günter; Krabisch, Peter; Kühn, Tilman; Richter, Angelika; Sigge, Claudia; Traeder, Wolfgang; Waldmann, Karl-Heinz; Wallmann, Jürgen; Werckenthin, Christiane; Schwarz, Stefan

    2004-01-01

    Two layouts for microtitre plates, which should serve for in-vitro susceptibility testing in routine diagnostics, have been set up by the working group "Antibiotic resistance" of the German Society for Veterinary Medicine. One of these layouts was designed for the testing of bacteria from cases of mastitis and the other for bacteria from infections in large food-producing animals. The choice of the antimicrobial agents and their concentrations to be included in these layouts were based on (1) the bacteria frequently associated with the respective diseases/animals, (2) the antimicrobial agents licensed for therapeutic use in these diseases/animals, (3) the currently available breakpoints, and (4) cross-resistances between the antimicrobial agerts so far known to occur in the respective bacteria. PMID:15298050

  17. Antimicrobial susceptibility of standard strains of nontuberculous mycobacteria by microplate Alamar Blue assay.

    PubMed

    Li, Guilian; Lian, Lu-Lu; Wan, Li; Zhang, Jingrui; Zhao, Xiuqin; Jiang, Yi; Zhao, Li-Li; Liu, Haican; Wan, Kanglin

    2013-01-01

    In this study, 24 standard nontuberculous mycobacteria (NTM) species strains including 12 slowly growing mycobacteria strains and 12 rapidly growing mycobacteria strains were subjected to drug susceptibility testing using microplate Alamar Blue assay-based 7H9 broth. The most active antimicrobial agents against the 24 NTM strains were streptomycin, amikacin, the fluoroquinolones, and the tetracyclines. Mycobacterium chelonae, Mycobacterium abscessus, Mycobacterium bolletii, and Mycobacterium simiae are resistant to most antimicrobial agents. The susceptibility results of this study from 24 NTM standard strains can be referenced by clinicians before susceptibility testing for clinical isolates is performed or when conditions do not allow for susceptibility testing. The application of broth-based methods is recommended by the Clinical and Laboratory Standards Institute, and the documentation of the susceptibility patterns of standard strains of mycobacteria can improve the international standardization of susceptibility testing methods. PMID:24386332

  18. In Vitro Antimicrobial Susceptibility Patterns of Blastocystis.

    PubMed

    Roberts, Tamalee; Bush, Stephen; Ellis, John; Harkness, John; Stark, Damien

    2015-08-01

    Blastocystis is the most common human enteric protist with controversial clinical significance. Metronidazole is considered a first-line treatment for Blastocystis infection; however, there has been increasing evidence for the lack of efficacy of this treatment. Treatment failure has been reported in several clinical cases, and recent in vitro studies have suggested the occurrence of metronidazole-resistant strains. In this study, we tested 12 Blastocystis isolates from 4 common Blastocystis subtypes (ST1, ST3, ST4, and ST8) against 12 commonly used antimicrobials (metronidazole, paromomycin, ornidazole, albendazole, ivermectin, trimethoprim-sulfamethoxazole [TMP-SMX], furazolidone, nitazoxanide, secnidazole, fluconazole, nystatin, and itraconazole) at 10 different concentrations in vitro. It was found that each subtype showed little sensitivity to the commonly used metronidazole, paromomycin, and triple therapy (furazolidone, nitazoxanide, and secnidazole). This study highlights the efficacy of other potential drug treatments, including trimethoprim-sulfamethoxazole and ivermectin, and suggests that current treatment regimens be revised. PMID:25987633

  19. In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

    PubMed Central

    Bush, Stephen; Ellis, John; Harkness, John; Stark, Damien

    2015-01-01

    Blastocystis is the most common human enteric protist with controversial clinical significance. Metronidazole is considered a first-line treatment for Blastocystis infection; however, there has been increasing evidence for the lack of efficacy of this treatment. Treatment failure has been reported in several clinical cases, and recent in vitro studies have suggested the occurrence of metronidazole-resistant strains. In this study, we tested 12 Blastocystis isolates from 4 common Blastocystis subtypes (ST1, ST3, ST4, and ST8) against 12 commonly used antimicrobials (metronidazole, paromomycin, ornidazole, albendazole, ivermectin, trimethoprim-sulfamethoxazole [TMP-SMX], furazolidone, nitazoxanide, secnidazole, fluconazole, nystatin, and itraconazole) at 10 different concentrations in vitro. It was found that each subtype showed little sensitivity to the commonly used metronidazole, paromomycin, and triple therapy (furazolidone, nitazoxanide, and secnidazole). This study highlights the efficacy of other potential drug treatments, including trimethoprim-sulfamethoxazole and ivermectin, and suggests that current treatment regimens be revised. PMID:25987633

  20. Susceptibility of archaea to antimicrobial agents: applications to clinical microbiology.

    PubMed

    Khelaifia, S; Drancourt, M

    2012-09-01

    We herein review the state of knowledge regarding the in vitro and in vivo susceptibility of archaea to antimicrobial agents, including some new molecules. Indeed, some archaea colonizing the human microbiota have been implicated in diseases such as periodontopathy. Archaea are characterized by their broad-spectrum resistance to antimicrobial agents. In particular, their cell wall lacks peptidoglycan, making them resistant to antimicrobial agents interfering with peptidoglycan biosynthesis. Archaea are, however, susceptible to the protein synthesis inhibitor fusidic acid and imidazole derivatives. Also, squalamine, an antimicrobial agent acting on the cell wall, proved effective against human methanogenic archaea. In vitro susceptibility data could be used to design protocols for the decontamination of complex microbiota and the selective isolation of archaea in anaerobic culture. PMID:22748132

  1. Prediction of piperacillin-tazobactam susceptibility among Enterobacteriaceae, Pseudomonas aeruginosa, and other bacteria using ticarcillin-clavulanic acid, ceftazidime, and other broad-spectrum antimicrobial in vitro test results.

    PubMed

    Jones, R N; Sutton, L D; Cantrell, H F; Lankford, R B

    1994-11-01

    The ability of various in vitro beta-lactam susceptibility test results to predict the susceptibility of piperacillin-tazobactam (a new beta-lactam-beta-lactamase inhibitor combination) was assessed using more than 46,000 recent clinical isolates. The organisms were tested by reference-quality National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution procedures and interpreted by the currently published NCCLS criteria. The recommended antimicrobial tests that would accurately predict the piperacillin-tazobactam in vitro efficacy had an overall very major, false-susceptible rate of only 0.6% (< or = 1.5% is acceptable). The following drug tests can be used to judge piperacillin-tazobactam activity and spectrum (low patient risk) conservatively: for Enterobacteriaceae use ticarcillin-clavulanic acid results (0.6% very major error); for Pseudomonas aeruginosa use piperacillin (0.1%) results; for enterococci use ampicillin or ampicillin-sulbactam (1.8%) results; for Haemophilus influenzae and Moraxella catarrhalis use cefotaxime or cefuroxime or ceftriaxone (1.5%); and for staphylococci use oxacillin by NCCLS recommendations. When the piperacillin-tazobactam testing reagents become available, the direct testing of this combination should be applied to relevant clinical isolates. The piperacillin-tazobactam break points should be reassessed as indicated by the cited minimum inhibitory concentration population analysis to improve predictive accuracy; H. influenzae susceptibility modified to < or = 2/4 micrograms/ml and Enterococcus species susceptibility tested at < or = 16/4 micrograms. PMID:7874881

  2. Susceptibility of Stenotrophomonas maltophilia clinical strains in China to antimicrobial combinations.

    PubMed

    Hu, Li-Fen; Gao, Li-Ping; Ye, Ying; Chen, Xi; Zhou, Xiang-Tian; Yang, Hai-Fei; Liiu, Yan-Yan; Mei, Qing; Li, Jia-Bin

    2014-10-01

    We aimed to investigate the activity levels of several combinations of antimicrobials against Stenotrophomonas maltophilia. In this study, the antimicrobial susceptibility of S. maltophilia clinical isolates was determined, and the synergistic activity of three pairs of antimicrobial combinations was evaluated by the fractional inhibitory concentration index (FICI). The antimicrobial susceptibility in vitro against 83 S. maltophilia strains was greater for minocycline (80·7%) than for trimethoprim-sulfamethoxazole (51·8%), and levofloxacin (50·6%). The rate of resistance was highest for ticarcillin-clavulanate and ceftazidime (63·8%) and resistance to trimethoprim-sulfamethoxazole (TMP-SMX) was 48·2%. All three combinations were tested against susceptible isolates. Two of the combinations, TMP-SMX+ceftazidime and levofloxacin+ceftazidime were more effective than the combination of TMP-SMX+levofloxacin. We recommend acquiring more clinical data in order to explore combination therapy, which is a promising treatment of S. maltophilia infections. PMID:24588423

  3. Antimicrobial susceptibilities and beta-lactamase characterization of Capnocytophaga species.

    PubMed Central

    Roscoe, D L; Zemcov, S J; Thornber, D; Wise, R; Clarke, A M

    1992-01-01

    Capnocytophaga species have been associated with a wide variety of infections in both immunocompetent and immunocompromised patients. On the basis of data from antimicrobial susceptibility studies, beta-lactam antibiotics have been considered efficacious therapy. Six of 19 isolates from primarily clinical sources across Canada demonstrated beta-lactamase production, and agar dilution susceptibility testing showed broad resistance to beta-lactam antibiotics. For the beta-lactamase producing isolates, clavulanate reduced the MIC of amoxicillin for 90% of the strains tested by 64-fold. Isolates were highly susceptible to clindamycin, imipenem, and ciprofloxacin. Characterization of the beta-lactamases produced by two of these isolates (Van1 and Van2) was performed. Isoelectric focusing revealed an identical isoelectric point of 5.6 for both enzymes, but they had markedly different relative hydrolysis efficiencies, and different conditions were required to extract the enzymes. This study demonstrates the production of different types of beta-lactamases by Capnocytophaga spp. and suggests the need to screen all clinical isolates of Capnocytophaga spp. for the presence of beta-lactamases. PMID:1444299

  4. [Study of phenotypical and antimicrobial susceptibility markers in enteric Escherichia coli strains].

    PubMed

    Aguila, Adalberto; Bernedo, Robert; Llop, Alina; Ramírez, Margarita; Bravo, Laura; Fernández, Anabel; Ledo, Yudith

    2007-01-01

    Forty strains of Escherichia coli isolated from children under 5 years of age with acute diarreas, coming from different provinces of the country , were analyzed. Four important phenotypical determinants were tested: sorbosa, sorbitol, enterohemolysin and 0157:H7 serology, in order to select those strains from enterohemorrhagic or Shiga toxin-producing category. Likewise, they were characterized by biotyping and antimicrobial susceptibility methods. The use of phenotypical tests showed six strains with presumptive characteristics, four of which were most likely to be Shiga toxin-producing strains. In antimicrobial susceptibility test, the strains showed high resistance mainly to ampicillin and trimethrophin-sulfamethoxasole. Another interesting finding were intermediate resistance and susceptibility values to augmentin, aztreonan and ceftriaxone. There were 12 antimicrobial resistance patterns of which 10 were multi-resistant. PMID:23427442

  5. In Vitro Antimicrobial Susceptibility of Nontuberculous Mycobacteria in Iran.

    PubMed

    Heidarieh, Parvin; Mirsaeidi, Mehdi; Hashemzadeh, Mohamad; Feizabadi, Mohamad Mehdi; Bostanabad, Saeed Zaker; Nobar, Mostafa Ghalami; Hashemi Shahraki, Abodolrazagh

    2016-03-01

    Many species of nontuberculous mycobacteria (NTM) have long been identified as important causes of human disease, the incidence of which is rising. Several reports have suggested increasing trend of both in vitro and in vivo resistance to available treatment regimes. The aim of this study was to evaluate antibiotic susceptibility of clinically relevant NTM isolates using standard microbroth dilution test. Antimicrobial susceptibility testing was performed following National Committee for Clinical Laboratory Standards methods for NTM isolates, including 85 Mycobacterium fortuitum, 39 Mycobacterium chelonae, and 30 Mycobacterium abscessus subsp. abscessus as rapidly growing mycobacteria and 48 Mycobacterium simiae and 40 Mycobacterium kansasii as slowly growing mycobacteria. All isolates were recovered from various types of clinical samples and identified by multilocus sequence analysis. Trimethoprim-sulfamethoxazole (TMP-SMZ), amikacin, tobramycin, clarithromycin, moxifloxacin, linezolid, and imipenem showed better activity against M. fortuitum rather than meropenem, ciprofloxacin, cefoxitin, and doxycycline. Amikacin was active against 93% of M. abscessus subsp. abscessus. Linezolid, clarithromycin, cefoxitin, ciprofloxacin, imipenem, moxifloxacin, tobramycin, TMP-SMZ, doxycycline, and meropenem showed some activities on M. abscessus subsp. abscessus as well. The majority of M. abscessus subsp. abscessus and M. chelonae strains were multidrug resistant. Among the 40 isolates of M. kansasii, all were susceptible to ethambutol, isoniazid, clarithromycin, moxifloxacin, and linezolid. These isolates were also resistant to doxycycline and 50% were resistant to rifampicin and ciprofloxacin. M. simiae was resistant to clarithromycin, doxycycline, isoniazid, and TMP-SMZ, and the majority of isolates showed high levels of resistance to linezolid, ethambutol, ciprofloxacin, streptomycin, and rifampicin. The majority of M. simiae isolates were multidrug resistant. Our data

  6. Antimicrobial Drug Susceptibility of Bacteria Isolated from Disease Processes in Cattle, Horses, Dogs and Cats

    PubMed Central

    Prescott, J. F.; Gannon, V. P.; Kittler, G.; Hlywka, G.

    1984-01-01

    Results are presented of antimicrobial disc diffusion susceptibility testing on commonly isolated bacterial pathogens made at the Ontario Veterinary College Diagnostic Bacteriology Laboratory in 1981 and 1982. Nearly 2 000 isolates from horses, cattle, dogs and cats were tested. Comparison of resistance in the same bacterial species isolated from different animal species showed significant differences between some of the same antibiotics. PMID:17422428

  7. Antimicrobial susceptibility of clinical isolates of Pseudomonas aeruginosa from a Malaysian Hospital.

    PubMed

    Pathmanathan, Siva Gowri; Samat, Nor Azura; Mohamed, Ramelah

    2009-04-01

    Ongoing surveillance of Pseudomonas aeruginosa resistance against antimicrobial agents is fundamental to monitor trends in susceptibility patterns and to appropriately guide clinicians in choosing empirical or directed therapy. The in vitro activity level of eight antimicrobial drugs was assessed against 97 clinical isolates of P. aeruginosa collected consecutively for three months in 2007 from a Malaysian hospital. Antimicrobial susceptibility was determined using the E-test method in addition to the hospital's routine diagnostic testing by the disk diffusion method. Respiratory and wound swab isolates were the most frequently encountered isolates. The E-test and disk diffusion methods showed high concordance in determining the in vitro activity of the antimicrobial agents against the E isolates. Piperacillin-tazobactam was the most active antimicrobial agent with 91.8% susceptibility, followed by the aminoglycosides (amikacin, 86.6% and gentamicin, 84.5%), the quinolone (ciprofloxacin, 83.5%) and the beta-lactams (cefepime, 80.4%, ceftazidime, 80.4%, imipenem, 79.4% and meropenem, 77.3%). Incidence of multidrug resistance was 19.6% (19 out of 97 isolates). Periodic antibiotic resistance surveillance is fundamental to monitor changes in susceptibility patterns in a hospital setting. PMID:22589655

  8. Campylobacter MLST Subtypes and Antimicrobial Susceptibility of Broiler Cecal Isolates: A Two Year Study from 142 Commercial Flocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Campylobacter spp. are recognized as important agents of human foodborne gastroenteritis. To monitor trends in food safety and public health, antimicrobial susceptibility testing of Campylobacter derived from poultry products and infected patients has become common practice in both r...

  9. Antimicrobial susceptibility of Lactobacillus species isolated from commercial ethanol plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial contamination of commercial fermentation cultures is a common and costly problem to the fuel ethanol industry. Antimicrobials such as virginiamycin (VIR) and penicillin (PEN) are frequently used to control contamination but there are little data available on the susceptibility of bacteria...

  10. Antimicrobial susceptibility of clinical isolates of Haemophilus influenzae to ampicillin-sulbactam.

    PubMed

    Mortensen, J E; LaRocco, M; Himes, S L; Inderlied, C; Daly, J A; Campos, J M; Mendelman, P M

    1990-01-01

    A total of 1092 clinical isolates of Haemophilus influenzae (306 type b; 786 non-type-b), from five medical centers were obtained during 1987 and 1988. Disk diffusion antimicrobial susceptibilities were obtained for all isolates, and broth microdilution susceptibilities were obtained for 502 isolates. Beta-lactamase was produced by 34.3% of type-b and 22.1% of non-type-b isolates, with some geographic variations. Using disk diffusion antimicrobial susceptibility testing, all isolates were susceptible to ampicillin-sulbactam, ceftriaxone, cefuroxime, and rifampin; two isolates were resistant to chloramphenicol. Whether tested using a fixed ratio of ampicillin to sulbactam of 2:1 or a fixed concentration of sulbactam, the ampicillin-sulbactam combination demonstrated good activity against clinical isolates of H. influenzae. Only 8 of the 1092 isolates did not produce beta-lactamase but demonstrated MICs of greater than or equal to 2 micrograms/ml for ampicillin. PMID:2076596

  11. Biochemical characteristics and antimicrobials susceptibility of Salmonella gallinarum isolated in Korea.

    PubMed

    Lee, Young-ju; Kim, Ki-seuk; Kwon, Yong-kuk; Tak, Ryun-bin

    2003-08-01

    Fowl typhoid (FT) reported since 1992 in Korea is a septicemic disease of domestic birds caused by Salmonella gallinarum (S. gallinarum). The purpose of this study was to investigate the biochemical characteristics and antimicrobials susceptibility of field isolates of S. gallinarum isolated by year in Korea. A total of 258 isolates of S. gallinarum from 1995 to 2001 showed the same pattern in the majority of biochemical test such as IMViC (indole, methyl red, Voges-Proskauer and citrate utilization), carbohydrate fermentation and amino acid decarboxylation, and these results were almost in accordance with the traditional biochemical characteristics of S. gallinarum strain. When the antimicrobial susceptibility test against 258 isolates of S. gallinarum was performed by the disk diffusion method using 12 antimicrobial agents, all isolates from 1995 appeared to be susceptible to all of the antimicrobial agents tested except for tetracycline and oxytetracycline, whereas the vast majority of isolates from 2001 showed the reduced susceptibility to ampicillin (13.0%), gentamicin (43.4%), kanamycin (69.6%), enrofloxacin (6.5%), ciprofloxacin (10.9%), norfloxacin (52.5%) and ofloxacin (82. 6%). The prevalence of the prevalence of completely resistant isolates resistant isolates to one or more drugs rapidly increased from 0% in 1995 to 93.5% in 2001. The minimal concentrations range of the majority of antimicrobial agents to inhibit 50% (MIC50s) against S. gallinarum isolates increased from 0.06 approximately 8 microg/ml in 1997 to 2 approximately 256 microg/ml in 2001. Especially, MIC50s for gentamicin and fluoroquinolones of isolates from 2001 increased over 10-fold than those of isolates from 1997. Therefore, our results indicate that sorbitol fermentation and arginine decarboxylation showed the diversity by isolates and the vast majority of isolates from 2001 showed the reduced susceptibility to antimicrobials tested. PMID:14610370

  12. [Antimicrobial susceptibility of Neisseria gonorrhoeae strains determined by disk diffusion].

    PubMed

    Llanes Caballero, R; Acosta Giraldo, J C; Sosa Puente, J; Guzmán Hernández, D; Gutiérrez González, O; Llop Hernández, A

    1999-01-01

    The Gonoccocus Laboratory of "Pedro Kourí" Tropical Medicine Institute carried out a study of in vitro susceptibility of Neisseria gonorrhoeae to penicillin, tetracycline, cefuroxime ceftriaxone, cefotaxine and ciprofoxacin by means of a disk diffusion method with the culture medium agar base GC plus supplement. In the first phase, the method was standardized and the reference N. gonorrhoeae ATCC 49226 strain was used whereas in the second phase, 50 gonococcal strains isolated in 8 provinces during 1995 and 1996 were examined. The results of such standardization confirmed that the antimicrobial susceptibility values were within the allowable limits. 52 and 34% of strains were resistant to penicillin and tetracycline respectively and all of them showed susceptibility to the rest of evaluated antimicrobial drugs. We recommend the use of the disk diffusion method for surveillance of gonococci resistance to these drugs in our country. PMID:10887570

  13. [Use of a program-specific website to disseminate data on antimicrobial susceptibility of clinical isolates from the Tigecycline Evaluation and Surveillance Trial (TEST)].

    PubMed

    Leclercq, R; Goulenok, C; Loncle-Provot, V

    2008-03-01

    Tigecycline Evaluation and Surveillance Trial (TEST) is an international surveillance study designed to assess the in vitro activity of tigecycline and 11 comparators against a range of important clinical pathogens from both the community and the hospital. The updated data obtained from the TEST program are integrated in a database server and available with a web application. The website has been designed to disseminate data collected from the international TEST program to the medical community and has been developed to be user-friendly. The use of this program-specific website can be made in a timely manner to extract antimicrobial resistance data of major microorganisms based on chosen selection criteria. This article describes how to use this web-based program for different analyse-types and the multiple options to display search results. Data can be presented in a table or as a graph or diagram, according to the source of the isolate, type of unit, resistance pattern of the pathogen. The website also allows the user to compare the data of antimicrobial testing at a national or regional level. It provides within a few minutes details on the activity of tigecycline and 11 comparators against clinical isolates collected all around the world. Main results of the TEST program on the in vitro activities of tigecyline against more 65,000 clinical isolates throughout the world are presented. The internet gives infectious diseases specialists and microbiologists the opportunity to have immediate access to continuously updated surveillance data. The TEST website should be helpful to clinicians to better select agents in severe infections, particularly for empirical treatment, that is at a time when the choice of the most appropriate antibiotic is essential for the outcome of the patient. PMID:18276097

  14. [Recommendations for selecting antimicrobial agents for in vitro susceptibility studies using automatic and semiautomatic systems].

    PubMed

    Cantón, Rafael; Alós, Juan Ignacio; Baquero, Fernando; Calvo, Jorge; Campos, José; Castillo, Javier; Cercenado, Emilia; Domínguez, M Angeles; Liñares, Josefina; López-Cerezo, Lorena; Marco, Francesc; Mirelis, Beatriz; Morosini, María-Isabel; Navarro, Ferran; Oliver, Antonio; Pérez-Trallero, Emilio; Torres, Carmen; Martínez-Martínez, Luis

    2007-01-01

    The number of clinical microbiology laboratories that have incorporated automatic susceptibility testing devices has increased in recent years. The majority of these systems determine MIC values using microdilution panels or specific cards, with grouping into clinical categories (susceptible, intermediate or resistant) and incorporate expert systems to infer resistance mechanisms. This document presents the recommendations of a group of experts designated by Grupo de Estudio de los Mecanismos de Acción y Resistencia a los Antimicrobianos (GEMARA, Study group on mechanisms of action and resistance to antimicrobial agents) and Mesa Española de Normalización de la Sensibilidad y Resistencia a los Antimicrobianos (MENSURA, Spanish Group for Normalizing Antimicrobial Susceptibility and Antimicrobial Resistance), with the aim of including antimicrobial agents and selecting concentrations for the susceptibility testing panels of automatic systems. The following have been defined: various antimicrobial categories (A: must be included in the study panel; B: inclusion is recommended; and C: inclusion is secondary, but may facilitate interpretative reading of the antibiogram) and groups (0: not used in therapeutics but may facilitate the detection of resistance mechanisms; 1: must be studied and always reported; 2: must be studied and selectively reported; 3: must be studied and reported at a second level; and 4: should be studied in urinary tract pathogens isolated in urine and other specimens). Recommended antimicrobial concentrations are adapted from the breakpoints established by EUCAST, CLSI and MENSURA. This approach will lead to more accurate susceptibility testing results with better detection of resistance mechanisms, and allowing to reach the clinical goal of the antibiogram. PMID:17583653

  15. In vitro susceptibility of Ornithobacterium rhinotracheale to several antimicrobial drugs.

    PubMed

    Soriano, V E; Vera, N A; Salado, C R; Fernández, R P; Blackall, P J

    2003-01-01

    As part of the basic characterization of Ornithobacterium rhinotracheale, the minimal inhibitory concentrations of 10 antimicrobial drugs were determined for reference strains and Mexican isolates by a broth microdilution method. For optimal growth of the organisms, a supplemented brain-heart infusion broth was used. The susceptibility of O. rhinotracheale to amoxicillin, enrofloxacin, and oxytetracycline was variable. However, consistent higher minimal inhibitory concentrations values were obtained for gentamicin, fosfomycin, trimethoprim, sulfamethazine, sulfamerazine, sulfaquinoxaline, and sulfachloropyridazine. Obtained results among Mexican isolates indicate a marked antimicrobial drug resistance trend. PMID:12887209

  16. Antimicrobial susceptibility among clinical Nocardia species identified by multilocus sequence analysis.

    PubMed

    McTaggart, Lisa R; Doucet, Jennifer; Witkowska, Maria; Richardson, Susan E

    2015-01-01

    Antimicrobial susceptibility patterns of 112 clinical isolates, 28 type strains, and 9 reference strains of Nocardia were determined using the Sensititre Rapmyco microdilution panel (Thermo Fisher, Inc.). Isolates were identified by highly discriminatory multilocus sequence analysis and were chosen to represent the diversity of species recovered from clinical specimens in Ontario, Canada. Susceptibility to the most commonly used drug, trimethoprim-sulfamethoxazole, was observed in 97% of isolates. Linezolid and amikacin were also highly effective; 100% and 99% of all isolates demonstrated a susceptible phenotype. For the remaining antimicrobials, resistance was species specific with isolates of Nocardia otitidiscaviarum, N. brasiliensis, N. abscessus complex, N. nova complex, N. transvalensis complex, N. farcinica, and N. cyriacigeorgica displaying the traditional characteristic drug pattern types. In addition, the antimicrobial susceptibility profiles of a variety of rarely encountered species isolated from clinical specimens are reported for the first time and were categorized into four additional drug pattern types. Finally, MICs for the control strains N. nova ATCC BAA-2227, N. asteroides ATCC 19247(T), and N. farcinica ATCC 23826 were robustly determined to demonstrate method reproducibility and suitability of the commercial Sensititre Rapmyco panel for antimicrobial susceptibility testing of Nocardia spp. isolated from clinical specimens. The reported values will facilitate quality control and standardization among laboratories. PMID:25348540

  17. Antimicrobial Susceptibility among Clinical Nocardia Species Identified by Multilocus Sequence Analysis

    PubMed Central

    Doucet, Jennifer; Witkowska, Maria; Richardson, Susan E.

    2014-01-01

    Antimicrobial susceptibility patterns of 112 clinical isolates, 28 type strains, and 9 reference strains of Nocardia were determined using the Sensititre Rapmyco microdilution panel (Thermo Fisher, Inc.). Isolates were identified by highly discriminatory multilocus sequence analysis and were chosen to represent the diversity of species recovered from clinical specimens in Ontario, Canada. Susceptibility to the most commonly used drug, trimethoprim-sulfamethoxazole, was observed in 97% of isolates. Linezolid and amikacin were also highly effective; 100% and 99% of all isolates demonstrated a susceptible phenotype. For the remaining antimicrobials, resistance was species specific with isolates of Nocardia otitidiscaviarum, N. brasiliensis, N. abscessus complex, N. nova complex, N. transvalensis complex, N. farcinica, and N. cyriacigeorgica displaying the traditional characteristic drug pattern types. In addition, the antimicrobial susceptibility profiles of a variety of rarely encountered species isolated from clinical specimens are reported for the first time and were categorized into four additional drug pattern types. Finally, MICs for the control strains N. nova ATCC BAA-2227, N. asteroides ATCC 19247T, and N. farcinica ATCC 23826 were robustly determined to demonstrate method reproducibility and suitability of the commercial Sensititre Rapmyco panel for antimicrobial susceptibility testing of Nocardia spp. isolated from clinical specimens. The reported values will facilitate quality control and standardization among laboratories. PMID:25348540

  18. Multicenter Study of Antimicrobial Susceptibility of Anaerobic Bacteria in Korea in 2012

    PubMed Central

    Lee, Yangsoon; Park, Yeon-Joon; Kim, Mi-Na; Uh, Young; Kim, Myung Sook

    2015-01-01

    Background Periodic monitoring of regional or institutional resistance trends of clinically important anaerobic bacteria is recommended, because the resistance of anaerobic pathogens to antimicrobial drugs and inappropriate therapy are associated with poor clinical outcomes. There has been no multicenter study of clinical anaerobic isolates in Korea. We aimed to determine the antimicrobial resistance patterns of clinically important anaerobes at multiple centers in Korea. Methods A total of 268 non-duplicated clinical isolates of anaerobic bacteria were collected from four large medical centers in Korea in 2012. Antimicrobial susceptibility was tested by the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin, piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, metronidazole, and tigecycline. Results Organisms of the Bacteroides fragilis group were highly susceptible to piperacillin-tazobactam, imipenem, and meropenem, as their resistance rates to these three antimicrobials were lower than 6%. For B. fragilis group isolates and anaerobic gram-positive cocci, the resistance rates to moxifloxacin were 12-25% and 11-13%, respectively. Among B. fragilis group organisms, the resistance rates to tigecycline were 16-17%. Two isolates of Finegoldia magna were non-susceptible to chloramphenicol (minimum inhibitory concentrations of 16-32 mg/L). Resistance patterns were different among the different hospitals. Conclusions Piperacillin-tazobactam, cefoxitin, and carbapemems are highly active β-lactam agents against most of the anaerobes. The resistance rates to moxifloxacin and tigecycline are slightly higher than those in the previous study. PMID:26206683

  19. Susceptibilities of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum strains to antimicrobial agents in vitro.

    PubMed Central

    ter Laak, E A; Noordergraaf, J H; Verschure, M H

    1993-01-01

    The purpose of this study was to determine the susceptibility of various strains of Mycoplasma bovis, Mycoplasma dispar, and Ureaplasma diversum, which are prevalent causes of pneumonia in calves, to 16 antimicrobial agents in vitro. The MICs of the antimicrobial agents were determined by a serial broth dilution method for 16 field strains and the type strain of M. bovis, for 19 field strains and the type strain of M. dispar, and for 17 field strains of U. diversum. Final MICs for M. bovis and M. dispar were read after 7 days and final MICs for U. diversum after 1 to 2 days. All strains tested were susceptible to tylosin, kitasamycin, and tiamulin but were resistant to nifuroquine and streptomycin. Most strains of U. diversum were intermediately susceptible to oxytetracycline but fully susceptible to chlortetracycline; most strains of M. bovis and M. dispar, however, were resistant to both agents. Strains of M. dispar and U. diversum were susceptible to doxycycline and minocycline, but strains of M. bovis were only intermediately susceptible. Susceptibility or resistance to chloramphenicol, spiramycin, spectinomycin, lincomycin, or enrofloxacin depended on the species but was not equal for the three species. The type strains of M. bovis and M. dispar were more susceptible to various antimicrobial agents, including tetracyclines, than the field strains. This finding might indicate that M. bovis and M. dispar strains are becoming resistant to these agents. Antimicrobial agents that are effective in vitro against all three mycoplasma species can be considered for treating mycoplasma infections in pneumonic calves. Therefore, tylosin, kitasamycin, and tiamulin may be preferred over oxytetracycline and chlortetracycline. PMID:8452363

  20. [Antimicrobial susceptibilities of clinical Nocardia isolates identified by 16S rRNA gene sequence analysis].

    PubMed

    Uner, Mahmut Celalettin; Hasçelik, Gülşen; Müştak, Hamit Kaan

    2016-01-01

    Nocardia species are ubiquitous in the environment and responsible for various human infections such as pulmonary, cutaneous, central nervous system and disseminated nocardiosis. Since the clinical pictures and antimicrobial susceptibilities of Nocardia species exhibit variability, susceptibility testing is recommended for every Nocardia isolates. The aims of this study was to determine the antimicrobial susceptibilities of Nocardia clinical isolates and to compare the results of broth microdilution and disc diffusion susceptibility tests. A total of 45 clinical Nocardia isolates (isolated from 17 respiratory tract, 8 brain abscess, 7 pus, 3 skin, 3 conjunctiva, 2 blood, 2 tissue, 2 pleural fluid and 1 cerebrospinal fluid samples) were identified by using conventional methods and 16S rRNA gene sequence analysis. Susceptibility testing was performed for amikacin, ciprofloxacin, ceftriaxone, linezolid and trimethoprim-sulfamethoxazole (TMP-SMX) by broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) criteria recommended in 2011 approved standard (M24-A2) and disk diffusion method used as an alternative comparative susceptibility testing method. Among the 45 Nocardia strains, N.cyriacigeorgica (n: 26, 57.8%) was the most common species, followed by N.farcinica (n: 12, 26.7%), N.otitiscaviarum (n: 4, 8.9%), N.asteroides (n: 1, 2.2%), N.neocaledoniensis (n: 1, 2.2%) and N.abscessus (n: 1, 2.2%). Amikacin and linezolid were the only two antimicrobials to which all isolates were susceptible for both broth microdilution and disk diffusion tests. In broth microdilution test, resistance rates to TMP-SMX, ceftriaxone and ciprofloxacin were found as 15.6%, 37.8% and 84.4% respectively, whereas in the disk diffusion test, the highest resistance rate was observed against ciprofloxacin (n: 33, 73.3%), followed by TMP-SMX (n: 22, 48.9%) and ceftriaxone (n: 15, 33.3%). In both of these tests, N.cyriacigeorgica was the species with the

  1. [Susceptibility and resistence of Pseudomonas aeruginosa to antimicrobial agents].

    PubMed

    Gamero Delgado, M C; García-Mayorgas, A D; Rodríguez, F; Ibarra, A; Casal, M

    2007-06-01

    Pseudomonas aeruginosa is an opportunistic microorganism that is frequently the cause of nosocomial infections. Multiple mechanisms are involved in its natural and acquired resistance to many of the antimicrobial agents commonly used in clinical practice. The objective of this study was to assess the susceptibility and resistance patterns of P. aeruginosa strains isolated in Hospital Reina Sofia between 2000 and 2005, as well as to analyze the differences between intrahospital and extrahospital isolates in 2005 and to compare the results with those obtained in other studies. A total of 3,019 strains of P. aeruginosa from different hospitals and nonhospital settings were evaluated, taking into consideration their degree of sensitivity to different antibiotics. The MICs were determined by means of the Wider I automated system (Soria Melguizo), taking into consideration the criteria of susceptibility and resistance recommended by MENSURA. Results of the analysis showed that P. aeruginosa maintained similar levels of antimicrobial susceptibility during the period 2000-2005, with increased susceptibility to amikacin, gentamicin and tobramycin. There were also important differences in the degree of susceptibility between intrahospital and extrahospital strains, except for imipenem and fosfomycin. The intrahospital difference in susceptibility was also evaluated, emphasizing the importance of periodically studying susceptibility and resistance patterns of P. aeruginosa in each setting in order to evaluate different therapeutic guidelines, as it is not always advisable to extrapolate data from different regions. These differences can be explained by the different use of antibiotics in each center and the geographic variations of the resistance mechanisms of P. aeruginosa. PMID:17893761

  2. Susceptibility of Anaerobic Bacteria to 23 Antimicrobial Agents

    PubMed Central

    Sutter, Vera L.; Finegold, Sydney M.

    1976-01-01

    The antimicrobial susceptibility of 492 anaerobic bacteria, the majority of which were recent clinical isolates, was determined by the agar dilution technique. Penicillin G was active against most of the strains tested at 32 U or less/ml, but only 72% of Bacteroides fragilis strains were susceptible at this level and 9% required 256 U or more/ml. Ampicillin was effective against most of the strains except B. fragilis at 16 μg or less/ml. Amoxicillin was active against only 31% of B. fragilis, 76% of other Bacteroides species, and 67% of Fusobacterium species at 8 μg/ml. Two new penicillins, mezlocillin and azlocillin, were similar to ampicillin in their activity. Carbenicillin and ticarcillin inhibited all but a few strains at 128 μg or less/ml. BLP 1654 was somewhat more active than penicillin G against B. fragilis but had similar activity against other anaerobes. Cephalothin was inactive against B. fragilis, and only 65% of other Bacteroides species were inhibited by 32 μg or less/ml. It was effective against all other anaerobes at that level. Cefamandole showed somewhat greater activity than cephalothin against B. fragilis but generally less activity against gram-positive organisms. Cefazaflur (SKF 59962) was comparable to cephalothin against B. fragilis. Cefoxitin was distinctly more active than cephalothin against B. fragilis. These latter two agents were less active than cephalothin against the gram-positive anaerobes. Chloramphenicol remains active against anaerobic bacteria at 16 μg or less/ml, with rare exceptions. Thiamphenicol was similar to chloramphenicol in its activity. Clindamycin was very active against most of the anaerobes at 8 μg or less/ml. Erythromycin and josamycin were also tested, with josamycin showing greater activity against B. fragilis than either erythromycin or clindamycin. A new oligosaccharide, everninomicin B, was less active than clindamycin against B. fragilis but more active against clostridia and some of the other strains

  3. Antimicrobial susceptibilities of canine Clostridium difficile and Clostridium perfringens isolates to commonly utilized antimicrobial drugs.

    PubMed

    Marks, Stanley L; Kather, Elizabeth J

    2003-06-24

    Clostridium difficile and Clostridium perfringens are anaerobic, Gram-positive bacilli that are common causes of enteritis and enterotoxemias in both domestic animals and humans. Both organisms have been associated with acute and chronic large and small bowel diarrhea, and acute hemorrhagic diarrheal syndrome in the dog. The objective of this study was to determine the in vitro antimicrobial susceptibilities of canine C. difficile and C. perfringens isolates in an effort to optimize antimicrobial therapy for dogs with clostridial-associated diarrhea. The minimum inhibitory concentrations (MIC) of antibiotics recommended for treating C. difficile (metronidazole, vancomycin) and C. perfringens-associated diarrhea in the dog (ampicillin, erythromycin, metronidazole, tetracycline, tylosin) were determined for 70 canine fecal C. difficile isolates and 131 C. perfringens isolates. All C. difficile isolates tested had an MIC of tested had an MIC for ampicillin of or=256 microg/ml for both erythromycin and tylosin. A third C. perfringens isolate had an MIC of 32 microg/ml for metronidazole. Based on the results of this study, ampicillin, erythromycin, metronidazole, and tylosin appear to be effective antibiotics for the treatment of C. perfringens-associated diarrhea, although resistant strains do exist. However, because there is limited information regarding breakpoints for veterinary anaerobes, and because intestinal concentrations are not known, in vitro results should be interpreted with caution. PMID:12742714

  4. In vitro antimicrobial susceptibility of Mycoplasma bovis clinical isolates recovered from bison (Bison bison).

    PubMed

    Suleman, Muhammad; Prysliak, Tracy; Windeyer, Claire; Perez-Casal, Jose

    2016-03-01

    Mycoplasma bovis is a pathogen globally affecting cattle and bison herds, causing pneumonia, arthritis, mastitis, abortions, and other symptoms, leading to huge economic losses. Many studies have been done regarding the antimicrobial susceptibility of M. bovis isolated from cattle, but no such study is available for isolates recovered from bison. For the first time, in vitro susceptibilities of 40 M. bovis clinical isolates collected from bison herds in Canada are reported here. Minimal inhibitory concentration (MIC) values were determined using Sensititre® plates. The most effective MIC50 and MIC90 were for spectinomycin (1 and >64 μg/mL), tiamulin (1 and >32 μg/mL), and tulathromycin (16 and 64 μg/mL), whereas tetracyclines, fluoroquinolones, and florfenicol failed to inhibit growth of M. bovis bison isolates. Isolates were nonsusceptible to tetracyclines (100%), fluoroquinolones (97.5%), and tilmicosin (100%), whereas the highest susceptibility of bison clinical isolates was seen with spectinomycin (95%) and tulathromycin (67.5%). Two lung isolates (Mb283 and 348) were found resistant to both spectinomycin and tulathromycin. These results show a marked difference in antimicrobial susceptibility of bison isolates as compared with previously reported and laboratory reference cattle isolates, emphasizing the necessity of testing antimicrobial susceptibility of M. bovis bison isolates and to generate better therapeutic regime for improved recovery chances for infected bison herds across North America. PMID:26854525

  5. Isolation Method (direct plating or enrichment) does not affect Antimicrobial Susceptibility of Campylobacter from Chicken Carcasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To determine if Campylobacter isolation method influenced antimicrobial susceptibility results, the minimum inhibitory concentrations (MIC) of nine antimicrobials were compared for 291 pairs of Campylobacter isolates recovered from chicken carcass rinse samples using direct plating and an enrichment...

  6. Antimicrobial susceptibility of Bacillus anthracis strains from Hungary.

    PubMed

    Kreizinger, Zsuzsa; Sulyok, Kinga Mária; Makrai, László; Rónai, Zsuzsanna; Fodor, László; Jánosi, Szilárd; Gyuranecz, Miklós

    2016-06-01

    The susceptibility of 29 Bacillus anthracis strains, collected in Hungary between 1933 and 2014, was tested to 10 antibiotics with commercially available minimum inhibitory concentration (MIC) test strips. All strains were susceptible to amoxicillin, ciprofloxacin, clindamycin, doxycycline, gentamicin, penicillin, rifampicin, and vancomycin. Intermediate susceptibility to erythromycin and cefotaxime was detected in 17.2% (5/29) and 58.6% (17/29) of the strains, respectively. Correlations were not observed between the isolation date, location, host species, genotype, and antibiotic susceptibility profile of strains. PMID:27342086

  7. Antimicrobial susceptibility pattern of Brachyspira intermedia isolates from European layers.

    PubMed

    Verlinden, Marc; Boyen, Filip; Pasmans, Frank; Garmyn, An; Haesebrouck, Freddy; Martel, An

    2011-09-01

    A broth microdilution method was used to determine the antimicrobial susceptibility of 20 Brachyspira intermedia isolates obtained from different layer flocks in Belgium and The Netherlands between 2008 and 2010. The antimicrobial agents used were tylosin, tilmicosin, tiamulin, valnemulin, doxycycline, and lincomycin. The minimal inhibitory concentration (MIC) distribution patterns of tylosin, tilmicosin, lincomycin, and doxycycline were bimodal, demonstrating acquired resistance against doxycycline in three strains, against the macrolides in two strains, and against lincomycin in one strain. The MICs of tiamulin and valnemulin showed a monomodal distribution, but with tailing toward the higher MIC values, possibly suggesting low-level acquired resistance in six isolates. Sequencing revealed a G1058C mutation in the 16S rRNA gene in all doxycycline-resistant strains. The strain resistant to tylosin, tilmicosin, and lincomycin had an A2058T mutation in the 23S rRNA gene. PMID:21663534

  8. Antimicrobial susceptibilities of Mycoplasma isolated from bovine mastitis in Japan.

    PubMed

    Kawai, Kazuhiro; Higuchi, Hidetoshi; Iwano, Hidetomo; Iwakuma, Akihiro; Onda, Ken; Sato, Reiichiro; Hayashi, Tomohito; Nagahata, Hajime; Oshida, Toshio

    2014-01-01

    Mycoplasma spp. are highly contagious pathogens and intramammary Mycoplasma infection is a serious issue for the dairy industry. As there is no effective vaccine for Mycoplasma infection, control depends on good husbandry and chemo-antibiotic therapy. In this study, antimicrobial susceptibility of Mycoplasma strains recently isolated from cases of bovine mastitis in Japan was evaluated by minimum inhibitory concentration (MIC). All Mycoplasma bovis strains were sensitive to pirlimycin, danofloxacin and enrofloxacin, but not kanamycin, oxytetracycline, tilmicosin or tylosin. M. californicum and M. bovigenitalium strains were sensitive to pirlimycin, danofloxacin, enrofloxacin, oxytetracycline, tilmicosin and tylosin, but not to kanamycin. This is the first report to describe the MIC of major antimicrobial agents for Mycoplasma species isolated from bovine mastitis in Japan. PMID:24261609

  9. Methods for broth dilution susceptibility testing of bacteria isolated from aquatic animals; approved guideline-second edition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing is recommended to determine which antimicrobial agents should be considered for treating a bacterial pathogen. Many bacteria that cause disease in aquatic animals require growth conditions that vary substantially from routine terrestrial pathogens. It has thus ...

  10. In vitro antimicrobial susceptibility of Mycoplasma bovis isolated in Israel from local and imported cattle.

    PubMed

    Gerchman, Irena; Levisohn, Sharon; Mikula, Inna; Lysnyansky, Inna

    2009-06-12

    Monitoring of susceptibility to antibiotics in field isolates of pathogenic bovine mycoplasmas is important for appropriate choice of treatment. Our study compared in vitro susceptibility profiles of Mycoplasma bovis clinical strains, isolated during 2005-2007 from Israeli and imported calves. Minimal inhibitory concentration (MIC) values were determined for macrolides by the microbroth dilution test, for aminoglycosides by commercial Etest, and for fluoroquinolones and tetracyclines by both methods. Notably, although correlation between the methods was generally good, it was not possible to determine the MIC endpoint for enrofloxacin-resistant strains (MIC > or =2.5 microg/ml in the microtest) by Etest. Comparison of antibiotic susceptibility profiles between local and imported M. bovis strains revealed that local strains were significantly more resistant to macrolides than most isolates from imported animals, with MIC(50) of 128 microg/ml vs. 2 microg/ml for tilmicosin and 8 microg/ml vs. 1 microg/ml for tylosin, respectively. However, local strains were more susceptible than most imported strains to fluoroquinolones and spectinomycin. Difference in susceptibility to tetracycline, doxycycline and oxytetracycline between local and imported strains was expressed in MIC(90) values for imported strains in the susceptible range compared to intermediate susceptibility for local strains. The marked difference in susceptibility profiles of M. bovis strains isolated from different geographical regions seen in this study emphasizes the necessity for performing of the antimicrobial susceptibility testing periodically and on a regional basis. PMID:19250777

  11. Current Concepts in Laboratory Testing to Guide Antimicrobial Therapy

    PubMed Central

    Jenkins, Stephen G.; Schuetz, Audrey N.

    2012-01-01

    Antimicrobial susceptibility testing (AST) is indicated for pathogens contributing to an infectious process that warrants antimicrobial therapy if susceptibility to antimicrobials cannot be predicted reliably based on knowledge of their identity. Such tests are most frequently used when the etiologic agents are members of species capable of demonstrating resistance to commonly prescribed antibiotics. Some organisms have predictable susceptibility to antimicrobial agents (ie, Streptococcus pyogenes to penicillin), and empirical therapy for these organisms is typically used. Therefore, AST for such pathogens is seldom required or performed. In addition, AST is valuable in evaluating the activity of new and experimental compounds and investigating the epidemiology of antimicrobial resistant pathogens. Several laboratory methods are available to characterize the in vitro susceptibility of bacteria to antimicrobial agents. When the nature of the infection is unclear and the culture yields mixed growth or usual microbiota (wherein the isolates usually bear little relationship to the actual infectious process), AST is usually unnecessary and results may, in fact, be dangerously misleading. Phenotypic methods for detection of specific antimicrobial resistance mechanisms are increasingly being used to complement AST (ie, inducible clindamycin resistance among several gram-positive bacteria) and to provide clinicians with preliminary direction for antibiotic selection pending results generated from standardized AST (ie, β-lactamase tests). In addition, molecular methods are being developed and incorporated by microbiology laboratories into resistance detection algorithms for rapid, sensitive assessment of carriage states of epidemiologically and clinically important pathogens, often directly from clinical specimens (ie, presence of vancomycin-resistant enterococci in fecal specimens). PMID:22386185

  12. Antimicrobial susceptibility of gram-positive udder pathogens from bovine mastitis milk in Switzerland.

    PubMed

    Overesch, G; Stephan, R; Perreten, V

    2013-06-01

    We evaluated the susceptibility of the gram-positive mastitis pathogens S. aureus, Str. uberis, Str. dysgalactiae, E. faecalis and L. garviae to antibiotics that are of epidemiological interest or are critically important for mastitis therapy and human medicine. Penicillin resistance was found to be most frequent in S. aureus, and nearly 5 % of the Str. uberis strains displayed a decreased susceptibility to this antibiotic. Resistance to aminoglycosides and macrolides was also detected in the strains tested. The detection of methicillin-resistant S. aureus (MRSA) and of a ciprofloxacin-resistant Str. dysgalactiae isolate corroborated the emergence of mastitis pathogens resistant to critically important antibiotics and underscores the importance of susceptibility testing prior to antibiotic therapy. The monitoring of antibiotic susceptibility patterns and antibiogram analyses are strongly recommended for targeted antimicrobial treatment and to avoid the unnecessary use of the latest generation of antibiotics. PMID:23732380

  13. Respiratory tract pathogens isolated from patients hospitalized with suspected pneumonia: frequency of occurrence and antimicrobial susceptibility patterns from the SENTRY Antimicrobial Surveillance Program (United States and Canada, 1997).

    PubMed

    Jones, R N; Croco, M A; Kugler, K C; Pfaller, M A; Beach, M L

    2000-06-01

    Thirty-seven sentinel hospitals (29 in the United States [US]; eight in Canada) collected bacterial isolates from hospitalized patients with a diagnosis of pneumonia. The antimicrobial susceptibility patterns of these pathogens were determined to more than 60 agents (40 reported) using the reference broth microdilution method described by the National Committee for Clinical Laboratory Standards. The five most frequently recorded species among the 2757 isolates collected during the study were (no. tested/%): Staphylococcus aureus (632/22.9%), Pseudomonas aeruginosa (498/18. 1%), Haemophilus influenzae (284/10.3%), Klebsiella spp. (240/8.7%), and Streptococcus pneumoniae (213/7.7%). There was a significant difference in the susceptibility to antimicrobials between the US and Canada for S. aureus to oxacillin (50.1% versus 93.8% susceptible, respectively), gentamicin (78.7% versus 97.8%), and fluoroquinolones (49.5 to 53.0% versus 89.8 to 94.9%). Amikacin (92. 8% susceptible) was the most active antimicrobial agent against P. aeruginosa, and meropenem was the most potent beta-lactam. Against H. influenzae, most drugs retained a high level of activity, whilst against the S. pneumoniae, only the newer fluoroquinolones (gatifloxacin, levofloxacin, sparfloxacin) remained highly effective in vitro. Only two antimicrobial agents (imipenem and meropenem) were >99% active against the Klebsiella spp. and Enterobacter spp. isolated in this survey (possess extended spectrum beta-lactamases or hyperproduction of Amp C cephalosporins); cefepime (95.6-100.0% susceptible) was significantly more active than other cephalosporins tested. Clonal, epidemic outbreaks of multiply resistant strains were very rare in monitored hospitals. In conclusion, important differences exist between the US and Canada in the susceptibility patterns of some respiratory tract pathogens to commonly used antimicrobial agents with Canadian strains generally being more susceptible to currently available

  14. [An update on antifungal susceptibility testing].

    PubMed

    Tapia P, Cecilia V

    2009-04-01

    Due to increasing of invasive fungal infections and emergeney of antifungal drugs resistant fungi, standardized methods of antifungal susceptibility testing (AST) have been developed. The Clinical Laboratory Standards Instutute (CLSI) and the European for Committee Antimicrobial Susceptibility Testing (EUCAST) have guidelines for susceptibility of yeasts by broth microdilution (M27-A2 and E. Dis. 7.1 documents, respectively). Both are equivalent, although they present methodological and interpretative breakpoints differences. In addition, the CLSI have the M38-A (for filamentous fungi) and M44-A (disk diffusion) documents, whereas EUCAST is developing a document for Aspergillus spp. Furthermore, commercial methods are available that display good correlation with the methods of reference such as E-test, Sensititre and Vitek2. The interpretation of the results must be careful because the determination of the minimum inhibitory concentration (CIM) is difficult for fungi, there are host factors involved and not always there is a correlation between MIC and clinical outcome. Due to these methods are laborious and require trained personnel, to ask for AST to a reference laboratory is recommendable. PMID:19621145

  15. Application of luciferase assay for ATP to antimicrobial drug susceptibility

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Picciolo, G. L.; Vellend, H.; Tuttle, S. A.; Barza, M. J.; Weinstein, L. (Inventor)

    1977-01-01

    The susceptibility of bacteria, particularly those derived from body fluids, to antimicrobial agents is determined in terms of an ATP index measured by culturing a bacterium in a growth medium. The amount of ATP is assayed in a sample of the cultured bacterium by measuring the amount of luminescent light emitted when the bacterial ATP is reacted with a luciferase-luciferin mixture. The sample of the cultured bacterium is subjected to an antibiotic agent. The amount of bacterial adenosine triphosphate is assayed after treatment with the antibiotic by measuring the luminescent light resulting from the reaction. The ATP index is determined from the values obtained from the assay procedures.

  16. Antimicrobial Susceptibility of Bordetella bronchiseptica Isolates from Swine and Companion Animals and Detection of Resistance Genes

    PubMed Central

    Prüller, Sandra; Rensch, Ulrike; Meemken, Diana; Kaspar, Heike; Kopp, Peter A.; Klein, Günter; Kehrenberg, Corinna

    2015-01-01

    Bordetella bronchiseptica causes infections of the respiratory tract in swine and other mammals and is a precursor for secondary infections with Pasteurella multocida. Treatment of B. bronchiseptica infections is conducted primarily with antimicrobial agents. Therefore it is essential to get an overview of the susceptibility status of these bacteria. The aim of this study was to comparatively analyse broth microdilution susceptibility testing according to CLSI recommendations with an incubation time of 16 to 20 hours and a longer incubation time of 24 hours, as recently proposed to obtain more homogenous MICs. Susceptibility testing against a panel of 22 antimicrobial agents and two fixed combinations was performed with 107 porcine isolates from different farms and regions in Germany and 43 isolates obtained from companion animals in Germany and other European countries. Isolates with increased MICs were investigated by PCR assays for the presence of resistance genes. For ampicillin, all 107 porcine isolates were classified as resistant, whereas only a single isolate was resistant to florfenicol. All isolates obtained from companion animals showed elevated MICs for β-lactam antibiotics and demonstrated an overall low susceptibility to cephalosporines. Extension of the incubation time resulted in 1–2 dilution steps higher MIC50 values of porcine isolates for seven antimicrobial agents tested, while isolates from companion animals exhibited twofold higher MIC50/90 values only for tetracycline and cefotaxime. For three antimicrobial agents, lower MIC50 and MIC90 values were detected for both, porcine and companion animal isolates. Among the 150 isolates tested, the resistance genes blaBOR-1 (n = 147), blaOXA-2, (n = 4), strA and strB (n = 17), sul1 (n = 10), sul2 (n = 73), dfrA7 (n = 3) and tet(A) (n = 8) were detected and a plasmid localisation was identified for several of the resistance genes. PMID:26275219

  17. Comparison of BDPhoenix and VITEK2 automated antimicrobial susceptibility test systems for extended-spectrum beta-lactamase detection in Escherichia coli and Klebsiella species clinical isolates.

    PubMed

    Stürenburg, Enno; Sobottka, Ingo; Feucht, Heinz-Hubert; Mack, Dietrich; Laufs, Rainer

    2003-01-01

    The present study compares the ability to detect extended-spectrum beta-lactamases (ESBL) among a collection of 34 ESBL producing clinical isolates belonging to Escherichia coli and Klebsiella species with two new rapid susceptibility and identification instruments-VITEK2 (bioMérieux, Marcy l'Etoile, France) vs. BDPhoenix (BD Biosciences, Sparks, MD). ESBL content in these isolates was previously characterized on the basis of PCR amplification and sequencing results which were used as the reference method in our evaluation. BDPhoenix correctly determined the ESBL outcome for all strains tested (100% detection rate), whereas VITEK2 was not able to detect the ESBL status in 5 isolates (85% detection rate). Detailed analysis revealed that the discrepancies were mainly observed with 'difficult-to-detect' strains. Misidentification was either due to low oximino cephalosporin MIC in these strains or was associated with pronounced 'cefotaximase' or 'ceftazidimase' phenotypes. Klebsiella oxytoca chromosomal beta-lactamase (K1) is phenotypically quite similar to ESBL enzymes. In order to evaluate whether the K1 and ESBL enzymes could be discriminated, we expanded our analysis by 8 clinical K. oxytoca strains with K1 phenotypes. VITEK2 gave excellent identification of these strains whereas 7 out of 8 were falsely labeled ESBL-positive by the BDPhoenix system. PMID:12573548

  18. Short communication: In vitro antimicrobial susceptibility of Mycoplasma agalactiae strains isolated from dairy goats.

    PubMed

    Paterna, A; Sánchez, A; Gómez-Martín, A; Corrales, J C; De la Fe, C; Contreras, A; Amores, J

    2013-01-01

    This study examined the susceptibility to several antimicrobials of 28 isolates of Mycoplasma agalactiae obtained from goats in a region (southeastern Spain) where contagious agalactia is endemic. For each isolate, the minimum inhibitory concentration (MIC) against 12 antimicrobials of the quinolone, macrolide, aminoglycoside, and tetracycline families was determined. The antimicrobials with the lowest MIC were enrofloxacin, ciprofloxacin, tylosin, and doxycycline, all with MIC90 (concentration at which growth of 90% of the isolates is inhibited) <1 µg/mL. Norfloxacin (a quinolone) showed a wide MIC range (0.1-12.8 µg/mL), suggesting a resistance mechanism toward this antimicrobial that was not elicited by enrofloxacin or ciprofloxacin (the other quinolones tested). Erythromycin showed the highest MIC90 such that its use against Mycoplasma agalactiae is not recommended. Finally, Mycoplasma agalactiae isolates obtained from goat herds with clinical symptoms of contagious agalactia featured higher MIC90 and MIC50 (concentration at which growth of 50% of the isolates is inhibited) values for many of the antimicrobials compared with isolates from asymptomatic animals. The relationship between the extensive use of antimicrobials in herds with clinical contagious agalactia and variations in MIC requires further study. PMID:24035026

  19. Antimicrobial susceptibility of Canadian isolates of Helicobacter pylori in Northeastern Ontario

    PubMed Central

    Eng, Nelson F; Ybazeta, Gustavo; Chapman, Katrina; Fraleigh, Nya L; Letto, Rebecca; Altman, Eleonora; Diaz-Mitoma, Francisco

    2015-01-01

    BACKGROUND: Helicobacter pylori plays a significant role in gastritis and ulcers. It is a carcinogen as defined by the WHO, and infection can result in adenocarcinomas and mucosa-associated lymphoid tissue lymphomas. In Canada, rates of antimicrobial resistance are relatively unknown, with very few studies conducted in the past 15 years. OBJECTIVE: To examine rates of resistance in Sudbury, Ontario, compare antimicrobial susceptibility methods and attempt to determine the molecular basis of antibiotic resistance. METHODS: Patients attending scheduled visits at Health Sciences North (Sudbury, Ontario) provided gastric biopsy samples on a volunteer basis. In total, 20 H pylori isolates were collected, and antimicrobial susceptibility testing (on amoxicillin, tetracycline, metronidazole, ciprofloxacin, levofloxacin and clarithromycin) was conducted using disk diffusion and E-test methods. Subsequently, genomic DNA from these isolates was sequenced to detect mutations associated with antimicrobial resistance. RESULTS: Sixty-five percent of the isolates were found to be resistant to at least one of the listed antibiotics according to E-test. Three isolates were found to be resistant to ≥3 of the above-mentioned antibiotics. Notably, 25% of the isolates were found to be resistant to both metronidazole and clarithromycin, two antibiotics that are normally prescribed as part of first-line regimens in the treatment of H pylori infections in Canada and most of the world. Among the resistant strains, the sequences of 23S ribosomal RNA and gyrA, which are linked to clarithromycin and ciprofloxacin/levofloxacin resistance, respectively, revealed the presence of known point mutations associated with antimicrobial resistance. CONCLUSIONS: In general, resistance to metronidazole, ciprofloxacin/levofloxacin and clarithromycin has increased since the studies in the early 2000s. These results suggest that surveillance programs of H pylori antibiotic resistance may need to be

  20. Decreased susceptibility of Neisseria gonorrhoeae isolates from Switzerland to Cefixime and Ceftriaxone: antimicrobial susceptibility data from 1990 and 2000 to 2012

    PubMed Central

    2013-01-01

    Background Neisseria gonorrhoeae can rapidly develop resistance to antimicrobial agents. Over the last years, decreased gonococcal susceptibility to third-generation cephalosporins, especially cefixime, emerged worldwide. Therefore, current international guidelines recommend dual therapy for gonorrhoea with ceftriaxone plus either azithromycin or doxycycline. Gonococcal susceptibility data in Switzerland are sparse. Methods We investigated the prevalence of antibiotic susceptibility of N. gonorrhoeae in specimens collected between 1990 and 2012 at the University of Zurich, Switzerland. Minimum inhibitory concentrations (MICs) for cefixime, ceftriaxone, ciprofloxacin, and penicillin were determined by Etests. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used to define reduced susceptibility. Results A total of 320 isolates were tested. Between 1990 and 2006 all tested samples were susceptible to both cephalosporins. Subsequently, the prevalence of elevated MICs for cefixime increased to 10.4% (2007/2008), 11.5% (2009/2010), and 11.4% (2011/2012); and for ceftriaxone to 2.4% (2007/2008), 4.7% (2009/2010), and 0% (2011/2012), respectively. The prevalence of resistance to ciprofloxacin (72.7%) and penicillin (22.7%) was high in 2011/2012. Conclusions Decreasing susceptibility of N. gonorrhoeae to third-generation cephalosporins in Switzerland supports treatment recommendations with ceftriaxone plus azithromycin or doxycycline. Health-care providers need to be aware of possible treatment failures with cephalosporins. Continued surveillance of gonococcal antimicrobial resistance is essential. PMID:24369054

  1. A survey of Clostridium spiroforme antimicrobial susceptibility in rabbit breeding.

    PubMed

    Agnoletti, Fabrizio; Ferro, Tiziana; Guolo, Angela; Marcon, Barbara; Cocchi, Monia; Drigo, Ilenia; Mazzolini, Elena; Bano, Luca

    2009-04-14

    Rabbit meat breeding may be heavily affected by enterotoxaemia due to Clostridium spiroforme. Data on its antimicrobial susceptibility are insufficient, presumably because of difficulties in cultivating and identifying the pathogen. Our aim is therefore to provide this information to veterinary practitioners by focusing on a panel of therapeutics used in intensive rabbit units. Lincomycin was also checked in order to investigate the origin of resistance to macrolides. Minimal inhibitory concentrations (MICs) were determined with the agar dilution method according to the CLSI M11-A7 protocol (2007). MIC(50) and MIC(90) were, respectively, 64 and 64microg/ml for tiamulin, 32 and 32microg/ml for norfloxacin, 0.063 and 0.125microg/ml for amoxicillin, and 8 and 16microg/ml for doxycycline. MIC(50) and MIC(90) were 256microg/ml for sulphadimethoxine, spiramycin and lincomycin. Our results have shown that intrinsic or acquired antimicrobial resistances are diffuse in the C. spiroforme population and suggest focusing on prevention rather than on treatment of clostridial overgrowth, by reducing risk factors and using antimicrobials prudently. PMID:19058929

  2. Antimicrobial Susceptibility Patterns of Enterococcus faecalis and Enterococcus faecium Isolated from Poultry Flocks in Germany.

    PubMed

    Maasjost, J; Mühldorfer, K; Cortez de Jäckel S; Hafez, H M

    2015-03-01

    Between 2010 and 2011, 145 Enterococcus isolates (Enterococcus faecalis, n = 127; Enterococcus faecium, n = 18) were collected during routine bacteriologic diagnostics from broilers, layers, and fattening turkeys in Germany showing various clinical signs. The susceptibility to 24 antimicrobial agents was investigated by broth microdilution test to determine minimum inhibitory concentrations (MICs). All E. faecalis isolates (n = 127) were susceptible to the beta-lactam antibiotics ampicillin, amoxicillin-clavulanic acid, and penicillin. Corresponding MIC with 50% inhibition (MIC50) and MIC with 90% inhibition (MIC90) values of these antimicrobial agents were at the lower end of the test range (≤ 4 μg/ml). In addition, no vancomycin-resistant enterococci (VRE) were found. High resistance rates were identified in both Enterococcus species for lincomycin (72%-99%) and tetracycline (67%-82%). Half or more than half of Enterococcus isolates were resistant to gentamicin (54%-72%) and the macrolide antibiotics erythromycin (44%-61%) and tylosin-tartate (44%-56%). Enterococcus faecalis isolated from fattening turkeys showed the highest prevalence of antimicrobial resistance compared to other poultry production systems. Eighty-nine out of 145 Enterococcus isolates were resistant to three or more antimicrobial classes. Again, turkeys stood out with 42 (8 1%) multiresistant isolates. The most-frequent resistance patterns of E. faecalis were gentamicin, lincomycin, and tetracycline in all poultry production systems. PMID:26292548

  3. Presence and antimicrobial susceptibility of Escherichia coli recovered from retail chicken in China.

    PubMed

    Wu, Qian; Xi, Meili; Lv, Xiaoying; Xu, Yunfeng; Feng, Yuqing; Li, Qiong; Yang, Qinnan; Xia, Xiaodong

    2014-10-01

    The aim of this study was to determine the prevalence and antimicrobial susceptibility of Escherichia coli in retail whole chicken in the People 9 s Republic of China. Five hundred seventy-six raw whole chicken samples, randomly purchased from 146 farmers' markets or supermarkets in four provinces from March through December 2010, were analyzed for E. coli contamination, and the E. coli isolates were further tested for the presence of virulence genes and antimicrobial susceptibility. The overall positive rate for E. coli in retail chicken was 69.1%. E. coli prevalence was the highest in Beijing (86.8%), followed by Henan province (78.5%), Shaanxi province (65.3%), and the lowest prevalence was found in Sichuan province (45.8%). Among 398 isolates recovered, only the eae gene was detected in one isolate; no other virulence genes were detected. Resistance was most common to tetracycline (84.4%), followed by nalidixic acid (74.1%), ampicillin (71.1%), trimethoprim-sulfamethoxazole (70.1%), amoxicillin-clavulanic acid (68.8%), and streptomycin (58.5%). Lower resistance was detected to chloramphenicol (43.7%), kanamycin (42.7%), ciprofloxacin (30.2%), gentamicin (29.4%), cefoperazone (13.6%), amikacin (12.6%), gatifloxacin (8%), and cefoxitin (7.8%). Only 3.8% of the isolates were susceptible to all tested antimicrobials. Six percent of the isolates displayed resistance to one antimicrobial, 6.3% to two, and 83.9% to three or more of the antimicrobials. Our findings indicate that retail chicken in China was commonly contaminated with E. coli, and many E. coli strains exhibited multiple drug resistance. The implementation of good manufacturing practices throughout the poultry production chain is necessary to reduce E. coli contamination in retail chicken, and the prudent use of antibiotics is imperative in poultry production in China. PMID:25285496

  4. Effect of Farnesol on Staphylococcus aureus Biofilm Formation and Antimicrobial Susceptibility

    PubMed Central

    Jabra-Rizk, M. A.; Meiller, T. F.; James, C. E.; Shirtliff, M. E.

    2006-01-01

    Staphylococcus aureus is among the leading pathogens causing bloodstream infections able to form biofilms on host tissue and indwelling medical devices and to persist and cause disease. Infections caused by S. aureus are becoming more difficult to treat because of increasing resistance to antibiotics. In a biofilm environment particularly, microbes exhibit enhanced resistance to antimicrobial agents. Recently, farnesol was described as a quorum-sensing molecule with possible antimicrobial properties. In this study, the effect of farnesol on methicillin-resistant and -susceptible strains of S. aureus was investigated. With viability assays, biofilm formation assessment, and ethidium bromide uptake testing, farnesol was shown to inhibit biofilm formation and compromise cell membrane integrity. The ability of farnesol to sensitize S. aureus to antimicrobials was assessed by agar disk diffusion and broth microdilution methods. For both strains of staphylococci, farnesol was only able to reverse resistance at a high concentration (150 μM). However, it was very successful at enhancing the antimicrobial efficacy of all of the antibiotics to which the strains were somewhat susceptible. Therefore, synergy testing of farnesol and gentamicin was performed with static biofilms exposed to various concentrations of both agents. Plate counts of harvested biofilm cells at 0, 4, and 24 h posttreatment indicated that the combined effect of gentamicin at 2.5 times the MIC and farnesol at 100 μM (22 μg/ml) was able to reduce bacterial populations by more than 2 log units, demonstrating synergy between the two antimicrobial agents. This observed sensitization of resistant strains to antimicrobials and the observed synergistic effect with gentamicin indicate a potential application for farnesol as an adjuvant therapeutic agent for the prevention of biofilm-related infections and promotion of drug resistance reversal. PMID:16569866

  5. Multicenter Laboratory Validation of Susceptibility Testing of Mycobacterium tuberculosis against Classical Second-Line and Newer Antimicrobial Drugs by Using the Radiometric BACTEC 460 Technique and the Proportion Method with Solid Media

    PubMed Central

    Pfyffer, Gaby E.; Bonato, Donald A.; Ebrahimzadeh, Adeleh; Gross, Wendy; Hotaling, Jacqueline; Kornblum, John; Laszlo, Adalbert; Roberts, Glenn; Salfinger, Max; Wittwer, Franziska; Siddiqi, Salman

    1999-01-01

    In a large multicenter study involving six major study sites in the United States, Canada, and Europe, the susceptibilities of 272 Mycobacterium tuberculosis strains to classical second-line antituberculosis (anti-TB) drugs (capreomycin, cycloserine, ethionamide, and kanamycin) and newer compounds (amikacin, clofazimine, ofloxacin, and rifabutin) were determined by the radiometric BACTEC 460 procedure and the conventional proportion method on Middlebrook 7H10 agar. Previously established critical concentrations for classical second-line anti-TB drugs were compared with several concentrations in liquid medium to establish equivalence. MICs of newer compounds determined in liquid medium were either the same or up to four times lower than those determined in agar medium. After establishing critical concentrations (breakpoints) in the extended testing of clinical isolates, we obtained an excellent overall correlation between the two systems, with no errors with amikacin, kanamycin, and ofloxacin and very few major or very major errors with the other drugs; however, for cycloserine, no breakpoint concentration could be recommended due to repeatedly inconsistent results by both methods. Based on these data we conclude that the BACTEC 460 procedure is a simple and rapid method requiring 4 to 8 days on average to generate accurate antimicrobial susceptibility testing (AST) results for eight anti-TB drugs other than those considered primary ones. These data not only fill a major gap of knowledge regarding the critical test concentrations of secondary anti-TB drugs but also provide a baseline for future evaluations of M. tuberculosis AST with the more recently developed, nonradiometric broth-based culture systems. PMID:10488174

  6. Comparative antimicrobial susceptibility of Listeria monocytogenes, L. innocua, and L. welshimeri.

    PubMed

    Davis, Johnnie A; Jackson, Charlene R

    2009-03-01

    The current study compared antimicrobial susceptibility of Listeria innocua, L. welshimeri, and L. monocytogenes isolated from various sources. Antimicrobial susceptibility testing was performed using a microbroth procedure with Sensititre minimum inhibitory concentration plates containing 18 antimicrobials. Resistant isolates were analyzed for the presence of antimicrobial resistance genes using PCR. The majority of L. monocytogenes isolates were resistant to oxacillin (99%, 89/90) and ceftriaxone (72%, 65/90), while few isolates were resistant to clindamycin (21%, 19/90) and ciprofloxacin (2%, 2/90). When selected sources of L. monocytogenes are compared, resistance to ceftriaxone, clindamycin, and oxacillin ranged from 27% to 86%, 7% to 43%, and 96% to 100%, respectively. Resistance to ciprofloxacin (6%, 2/34), quinupristin/dalfopristin (7%, 1/14), and tetracycline (7%, 1/15) was observed with L. monocytogenes isolated from food, animal, and environmental sources, respectively. All L. welshimeri isolates (6/6) were resistant to streptomycin, quinupristin/dalfopristin, ciprofloxacin, rifampin, oxacillin, penicillin, and clindamycin, while most isolates (67%, 4/6) were resistant to trimethoprim/sulfamethoxazole. All L. innocua isolates (4/4) were resistant to oxacillin and penicillin, whereas 75% (3/4) of isolates were resistant to tetracycline, ceftriaxone, and clindamycin. Resistant isolates were negative for aadA, strA-B, sul I-II, penA, vat(A-E), vga(A-B), and vgb(A-B). However, tetM was detected among tetracycline-resistant isolates. L. welshimeri was resistant to more of the tested antimicrobials than the other two Listeria species tested, but resistance was not attributed to selected resistance genes. These data demonstrate the variability in resistance among Listeria species. However, the human pathogen L. monocytogenes appears to be the least resistant among the tested species. PMID:19216646

  7. Antimicrobial susceptibility in gram-negative bacteremia: are nosocomial isolates really more resistant?

    PubMed Central

    McGowan, J E; Hall, E C; Parrott, P L

    1989-01-01

    Bloodstream isolates of gram-negative aerobic bacilli from nosocomial infections are more likely to be resistant to antimicrobial agents than isolates from community-acquired cases are. It is not clear, however, how much this is due to the markedly different distribution of organisms in the two groups. We compared the susceptibilities of organisms of a given species which caused community-acquired bacteremia with the susceptibilities of isolates from nosocomial cases. Nine antimicrobial agents were tested against 1,077 isolates which were obtained during a 4-year nonepidemic period. Marked differences in crude rates of resistance were noted for all isolates from nosocomial cases versus all isolates from cases acquired in the community. When results were adjusted for the different organism distributions in the two groups, statistically significant differences were found for only six drug-organism pairs; in each of these, resistance rates were higher in nosocomial isolates. However, when results were further adjusted for the effect of multiple analyses, no significant differences were seen. The major factor leading to the greater prevalence of antimicrobial resistance in our hospital organisms was the markedly different distribution of organisms in the nosocomial and community-acquired groups. For individual organisms, greater resistance in nosocomial strains was confined to certain drugs. Factors that influence differences in organism distribution may not be solely the result of antimicrobial use. PMID:2610495

  8. Antimicrobial susceptibility of clinically isolated anaerobic bacteria in a University Hospital Centre Split, Croatia in 2013.

    PubMed

    Novak, Anita; Rubic, Zana; Dogas, Varja; Goic-Barisic, Ivana; Radic, Marina; Tonkic, Marija

    2015-02-01

    Anaerobic bacteria play a significant role in many endogenous polymicrobial infections. Since antimicrobial resistance among anaerobes has increased worldwide, it is useful to provide local susceptibility data to guide empirical therapy. The present study reports recent data on the susceptibility of clinically relevant anaerobes in a University Hospital Centre (UHC) Split, Croatia. A total of 63 Gram-negative and 59 Gram-positive anaerobic clinical isolates from various body sites were consecutively collected from January to December 2013. Antimicrobial susceptibility testing was performed using standardized methods and interpreted using EUCAST criteria. Patient's clinical and demographic data were recorded by clinical microbiologist. Among 35 isolates of Bacteroides spp., 97.1% were resistant to penicillin (PCN), 5.7% to amoxicillin/clavulanic acid (AMC), 8.6% to piperacillin/tazobactam (TZP), 29.0% to clindamycin (CLI) and 2.9% to metronidazole (MZ). Percentages of susceptible strains to imipenem (IPM), meropenem (MEM) and ertapenem (ETP) were 94.3. Resistance of other Gram-negative bacilli was 76.0% to PCN, 8.0% to AMC, 12.0% to TZP, 28.0% to CLI and 8% to MZ. All other Gram-negative strains were fully susceptible to MEM and ETP, while 96.0% were susceptible to IPM. Clostridium spp. isolates were 100% susceptible to all tested antibiotics except to CLI (two of four tested isolates were resistant). Propionibacterium spp. showed resistance to CLI in 4.3%, while 100% were resistant to MZ. Among other Gram-positive bacilli, 18.2% were resistant to PCN, 9.1% to CLI and 54.5% to MZ, while 81.8% of isolates were susceptible to carbapenems. Gram-positive cocci were 100% susceptible to all tested antimicrobials except to MZ, where 28.6% of resistant strains were recorded. Abdomen was the most common source of isolates (82.5%). The most prevalent types of infection were abscess (22.1%), sepsis (14.8%), appendicitis (13.9%) and peritonitis (6.6%). Twenty four patients (19

  9. Direct Identification and Antimicrobial Susceptibility Testing of Bacteria From Positive Blood Culture Bottles by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and the Vitek 2 System

    PubMed Central

    Jo, Sung Jin; Park, Kang Gyun; Han, Kyungja; Park, Dong Jin

    2016-01-01

    Background We evaluated the reliability and accuracy of the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial identification and Vitek 2 antimicrobial susceptibility testing (AST) for bacteria from positive blood culture bottles. Methods Direct identification and AST were performed in parallel to the standard methods in monomicrobial positive blood culture bottles. In total, 254 isolates grown on aerobic and/or anaerobic bottles were identified with MALDI-TOF Vitek MS (bioMérieux, France), and 1,978 microorganism/antimicrobial agent combinations were assessed. For isolates from anaerobic bottles, an aliquot of the culture broth was centrifuged, washed, and filtered through a nylon mesh. For isolates from aerobic/pediatric bottles, a lysis step using 9.26% ammonium chloride solution and 2% saponin solution was included. Results The overall correct identification rate was 81.8% (208/254) and that for gram-positive/gram-negative isolates was 73.9%/92.6%, respectively, and it was 81.8%, 87.6%, and 57.9% for isolates from aerobic, anaerobic, and pediatric bottles, respectively. Identification was not possible in 45 cases, and most of these isolates were streptococci (N=14) and coagulase-negative staphylococci (N=11). Misidentification occurred only in one case. Compared with standard methods, direct AST showed 97.9% (1,936/1,978) agreement with very major error of 0.25%, major error of 0.05%, and minor error of 1.8%. Conclusions This simple and cost-effective sample preparation method gives reliable results for the direct identification and AST of bacteria. For the identification of streptococci and coagulase-negative staphylococci, the method should be further improved. PMID:26709258

  10. In vitro susceptibility of Helicobacter pullorum strains to different antimicrobial agents.

    PubMed

    Ceelen, Liesbeth; Decostere, Annemie; Devriese, Luc A; Ducatelle, Richard; Haesebrouck, Freddy

    2005-01-01

    The in vitro activity of 13 antimicrobial agents against 23 Helicobacter pullorum strains from poultry (21) and human (two) origin, and one human H. canadensis strain was tested by the agar dilution method. With the H. pullorum strains, monomodal distributions of Minimum Inhibitory Concentrations (MICs) were seen with lincomycin, doxycycline, gentamicin, tobramycin, erythromycin, tylosin, metronidazole, and enrofloxacin in concentration ranges considered as indicating susceptibility in other bacteria. The normal susceptibility level for nalidixic acid was situated at or slightly above the MIC breakpoints proposed for Campylobacteriaceae. Ampicillin, ceftriaxone, and sulphamethoxazole-trimethoprim showed poor activity against H. pullorum. For the H. canadensis strain, a similar susceptibility pattern was seen, except for nalidixic acid and enrofloxacin, whose MIC of >512 and 8 microg/ml, respectively, indicated resistance of this agent. With spectinomycin, a bimodal distribution of the MICs was noted for the tested strains; eight H. pullorum isolates originating from one flock showed acquired resistance (MIC>512 microg/ml). PMID:15910225

  11. In vitro susceptibility testing of Dientamoeba fragilis.

    PubMed

    Nagata, N; Marriott, D; Harkness, J; Ellis, J T; Stark, D

    2012-01-01

    Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis, designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2 μg/ml to 500 μg/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 μg/ml; ronidazole, 8 to 16 μg/ml; tinidazole, 31 μg/ml; metronidazole, 31 μg/ml; secnidazole, 31 to 63 μg/ml; nitazoxanide, 63 μg/ml; tetracycline, 250 μg/ml; furazolidone, 250 to 500 μg/ml; iodoquinol, 500 μg/ml; paromomycin, 500 μg/ml; and diloxanide furoate, >500 μg/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis. Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis. PMID:22024820

  12. In Vitro Susceptibility Testing of Dientamoeba fragilis

    PubMed Central

    Nagata, N.; Marriott, D.; Harkness, J.; Ellis, J. T.

    2012-01-01

    Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis, designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2 μg/ml to 500 μg/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 μg/ml; ronidazole, 8 to 16 μg/ml; tinidazole, 31 μg/ml; metronidazole, 31 μg/ml; secnidazole, 31 to 63 μg/ml; nitazoxanide, 63 μg/ml; tetracycline, 250 μg/ml; furazolidone, 250 to 500 μg/ml; iodoquinol, 500 μg/ml; paromomycin, 500 μg/ml; and diloxanide furoate, >500 μg/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis. Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis. PMID:22024820

  13. Salmonella Prevalence and Antimicrobial Susceptibility from the National Animal Health Monitoring System Sheep 2011 Study.

    PubMed

    Dargatz, David A; Marshall, Katherine L; Fedorka-Cray, Paula J; Erdman, Matthew M; Kopral, Christine A

    2015-12-01

    Salmonella is a major cause of foodborne illness and can cause clinical disease in animals. Understanding the on-farm ecology of Salmonella will be helpful in decreasing the risk of foodborne transmission. An objective of this study was to determine the prevalence of Salmonella among fecal samples collected on sheep operations in the United States. Another objective was to compare the use of composite fecal samples with fecal samples collected from individual sheep as a tool for screening sheep flocks for Salmonella. Sheep fecal samples (individual and composite) were collected on operations in 22 states. Salmonella isolates were characterized with regard to species, serotype, and antimicrobial susceptibility profile. Most operations (72.1%) had at least one positive sample and overall 26.9% of samples were positive. The percentage of positive samples varied by animal age class. Composite and individual samples gave similar results. The majority of the isolates (94%) were Salmonella enterica subspecies diarizonae serotype 61:-:1,5,7. Nearly all of the isolates (91.2%) tested for antimicrobial susceptibility were susceptible to all antimicrobials in the panel. The findings suggest that salmonellae typically associated with foodborne disease transmission are infrequently found on sheep operations in the United States. PMID:26540254

  14. TESTING ANTIMICROBIAL EFFICACY ON POROUS MATERIALS

    EPA Science Inventory

    The efficacy of antimicrobial treatments to eliminate or control biological growth in the indoor environment can easily be tested on nonporous surfaces. However, the testing of antimicrobial efficacy on porous surfaces, such as those found in the indoor environment [i.e., gypsum ...

  15. Susceptibility testing of Entamoeba histolytica

    SciTech Connect

    Cedeno, J.R.; Krogstad, D.J.

    1983-12-01

    The growth of Entamoeba histolytica in microtiter plates in vitro in a variety of environments with reduced oxygen tensions is reported. With 3% O/sub 2/, 3% CO/sub 2/, and 94% N/sub 2/, the parasite growth in microtiter plates was identical to that in screw-capped culture tubes, as measured by (/sup 3/H)thymidine incorporation and by quantitative parasite counts. There were no significant differences between the drug concentrations necessary to inhibit parasite growth by 50% based on (/sup 3/H)thymidine incorporation vs those defined by quantitative parasite counts for the 15 antimicrobial agents tested (including seven drugs used for the treatment of amebiasis). This technique provides a reproducible method to quantitate the activity of potential antiamebic agents in vitro. The isotopic method should be of particular value in defining the metabolism of the parasite and effects of antimicrobial agents on it, whereas the morphologic method may be more valuable for workers with limited resources available to them.

  16. Susceptibility of Urinary Tract Bacteria to Newer Antimicrobial Drugs.

    PubMed

    Mehta, Manjula; Sharma, Jyoti; Bhardwaj, Sonia

    2016-03-15

    Urinary tract infections (UTIs) are among the commonest types of bacterial infections. The antibiotic treatment for UTIs is associated with important medical and economic implications. Many different microorganisms can cause UTIs though the most common pathogens are E. coli and members of family Enterobacteriaceae. The knowledge of etiology and antibiotic resistance pattern of the organisms causing urinary tract infection is essential. The present study was undertaken to evaluate trends of antibiotic susceptibility of commonly isolated uropathogens using newer antimicrobial agents, prulifloxacin, fosfomycin (FOM) and doripenem. We conclude that maintaining a record of culture results and the antibiogram may help clinicians to determine the empirical and/or specific treatment based on the antibiogram of the isolate for better therapeutic outcome. PMID:27275323

  17. Susceptibility of Urinary Tract Bacteria to Newer Antimicrobial Drugs

    PubMed Central

    Mehta, Manjula; Sharma, Jyoti; Bhardwaj, Sonia

    2016-01-01

    Urinary tract infections (UTIs) are among the commonest types of bacterial infections. The antibiotic treatment for UTIs is associated with important medical and economic implications. Many different microorganisms can cause UTIs though the most common pathogens are E. coli and members of family Enterobacteriaceae. The knowledge of etiology and antibiotic resistance pattern of the organisms causing urinary tract infection is essential. The present study was undertaken to evaluate trends of antibiotic susceptibility of commonly isolated uropathogens using newer antimicrobial agents, prulifloxacin, fosfomycin (FOM) and doripenem. We conclude that maintaining a record of culture results and the antibiogram may help clinicians to determine the empirical and/or specific treatment based on the antibiogram of the isolate for better therapeutic outcome. PMID:27275323

  18. Antimicrobial resistance in methicillin susceptible and methicillin resistant Staphylococcus pseudintermedius of canine origin: literature review from 1980 to 2013.

    PubMed

    Moodley, Arshnee; Damborg, Peter; Nielsen, Søren Saxmose

    2014-07-16

    Staphylococcus pseudintermedius is a commensal and a common opportunistic pathogen causing mainly infections of the integumentary system in dogs. The recent emergence of multidrug-resistant S. pseudintermedius isolates, in particular methicillin-resistant strains (MRSP) is a threat to small animal health and highlights the need for antimicrobial resistance surveillance to detect trends and potentially perform timeous interventions. We systematically reviewed 202 published articles to investigate temporal changes in antimicrobial resistance in clinical and commensal S. pseudintermedius isolated from dogs in 27 countries between 1980 and 2013. Resistance to the most common antimicrobials tested for in published studies and important for the treatment of staphylococcal infections in dogs were assessed separately for methicillin resistant (MRSP) and methicillin susceptible (MSSP) isolates. Stratified by MSSP and MRSP, no significant increases in antimicrobial resistance were observed over time, except for the penicillinase-labile penicillins (penicillin and ampicillin) among MSSP. However, in recent years, a few studies have reported higher-level of resistance to amikacin, gentamicin and enrofloxacin amongst MSSP. The review highlights inconsistencies between studies as a result of several factors, for example the use of different antimicrobial susceptibility testing methods and interpretation criteria. We recommend that data on susceptibility in important companion animal pathogens are collected and presented in a more harmonized way to allow more precise comparison of susceptibility patterns between studies. One way to accomplish this would be through systematic surveillance either at the country-level or at a larger scale across countries e.g. EU level. PMID:24613081

  19. Isolation and antimicrobial susceptibility of Plesiomonas shigelloides from great cormorants (Phalacrocorax carbo hanedae) in Gifu and Shiga Prefectures, Japan

    PubMed Central

    MATSUYAMA, Ryota; KUNINAGA, Naotoshi; MORIMOTO, Tomoya; SHIBANO, Tetsuya; SUDO, Akiko; SUDO, Kazunari; ASANO, Makoto; SUZUKI, Masatsugu; ASAI, Tetsuo

    2015-01-01

    Plesiomonas shigelloides is a causal agent of gastroenteritis, sepsis and meningitis in humans. We examined the prevalence of P. shigelloides among great cormorants (Phalacrocorax carbo hanedae) in Japan and the antimicrobial susceptibility of isolates. P. shigelloides was isolated from 33 (47.8%) of 69 fecal samples from great cormorants in 2014. All 33 isolates were subjected to antimicrobial susceptibility testing using broth microdilution methods, which showed resistance to ampicillin (31 isolates, 93.9%), tetracycline (two isolates, 6.1%) and trimethoprim (one isolate, 3.0%). The high prevalence of P. shigelloides in the great cormorants implicates the possible microbiological risk to public health. PMID:25892535

  20. Antimicrobial susceptibility and clarithromycin resistance patterns of Helicobacter pylori clinical isolates in Vietnam

    PubMed Central

    Quek, Camelia; Pham, Son T.; Tran, Kieu T.; Pham, Binh T.; Huynh, Loc V.; Luu, Ngan B.L.; Le, Thao K.T.; Quek, Kelly; Pham, Van H.

    2016-01-01

    Helicobacter pylori is a gastric pathogen that causes several gastroduodenal disorders such as peptic ulcer disease and gastric cancer.  Eradication efforts of H. pylori are often hampered by antimicrobial resistance in many countries, including Vietnam.  Here, the study aimed to investigate the occurrence of antimicrobial resistance among H. pylori clinical isolates across 13 hospitals in Vietnam.  The study further evaluated the clarithromycin resistance patterns of H. pylori strains.  In order to address the study interests, antimicrobial susceptibility testing, epsilometer test and PCR-based sequencing were performed on a total of 193 strains isolated from patients, including 136 children (3–15 years of age) and 57 adults (19–69 years of age).  Antimicrobial susceptibility testing showed that the overall resistance to amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline was 10.4%, 85.5%, 24.4%, 37.8%, and 23.8% respectively.  The distribution of minimum inhibitory concentrations (MICs) of clarithromycin-resistant strains was 85.5% with MIC >0.5 μg/mL.  The majority of the clarithromycin resistant isolates (135 of 165 subjects) have MICs ranging from 2 μg/mL to 16 μg/mL.  Furthermore, sequencing detection of mutations in 23S rRNA gene revealed that strains resistant and susceptible to clarithromycin contained both A2143G and T2182C mutations.  Of all isolates, eight clarithromycin-resistant isolates (MIC >0.5 μg/mL) had no mutations in the 23S rRNA gene.  Collectively, these results demonstrated that a proportion of clarithromycin-resistant H. pylori strains, which are not related to the 23S rRNA gene mutations, could be potentially related to other mechanisms such as the presence of an efflux pump or polymorphisms in the CYP2C19 gene.  Therefore, the present study suggests that providing susceptibility testing prior to treatment or alternative screening strategies for antimicrobial resistance is important for future

  1. Antimicrobial susceptibility and clarithromycin resistance patterns of Helicobacter pylori clinical isolates in Vietnam.

    PubMed

    Quek, Camelia; Pham, Son T; Tran, Kieu T; Pham, Binh T; Huynh, Loc V; Luu, Ngan B L; Le, Thao K T; Quek, Kelly; Pham, Van H

    2016-01-01

    Helicobacter pylori is a gastric pathogen that causes several gastroduodenal disorders such as peptic ulcer disease and gastric cancer.  Eradication efforts of H. pylori are often hampered by antimicrobial resistance in many countries, including Vietnam.  Here, the study aimed to investigate the occurrence of antimicrobial resistance among H. pylori clinical isolates across 13 hospitals in Vietnam.  The study further evaluated the clarithromycin resistance patterns of H. pylori strains.  In order to address the study interests, antimicrobial susceptibility testing, epsilometer test and PCR-based sequencing were performed on a total of 193 strains isolated from patients, including 136 children (3-15 years of age) and 57 adults (19-69 years of age).  Antimicrobial susceptibility testing showed that the overall resistance to amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline was 10.4%, 85.5%, 24.4%, 37.8%, and 23.8% respectively.  The distribution of minimum inhibitory concentrations (MICs) of clarithromycin-resistant strains was 85.5% with MIC >0.5 μg/mL.  The majority of the clarithromycin resistant isolates (135 of 165 subjects) have MICs ranging from 2 μg/mL to 16 μg/mL.  Furthermore, sequencing detection of mutations in 23S rRNA gene revealed that strains resistant and susceptible to clarithromycin contained both A2143G and T2182C mutations.  Of all isolates, eight clarithromycin-resistant isolates (MIC >0.5 μg/mL) had no mutations in the 23S rRNA gene.  Collectively, these results demonstrated that a proportion of clarithromycin-resistant H. pylori strains, which are not related to the 23S rRNA gene mutations, could be potentially related to other mechanisms such as the presence of an efflux pump or polymorphisms in the CYP2C19 gene.  Therefore, the present study suggests that providing susceptibility testing prior to treatment or alternative screening strategies for antimicrobial resistance is important for future clinical

  2. Antimicrobial susceptibility of clinical isolates of Acinetobacter baumannii.

    PubMed

    Shi, Z Y; Liu, P Y; Lau, Y; Lin, Y; Hu, B S; Shir J-M

    1996-02-01

    The in-vitro activity of 18 antimicrobial agents alone or in combination against 248 clinical isolates of Acinetobacter baumannii from Taiwan were tested by agar dilution. The MIC90S of ampicillin, amoxicillin, piperacillin, cefuroxime, cefotaxime, ceftriaxone, gentamicin, and amikacin were at least 128 mu g/ml. Ceftazidime, cefepime, sulbactam, clavulanic acid, and tazobactam presented moderate activity with MIC90S of 32, 16, 16, 32, and 32 mu g/ml, respectively. The increased activity of ampicillin/sulbactam, amoxicillin/clavulanic acid, and piperacillin/tazobactam was due to the intrinsic effect of sulbactam, clavulanic acid, and tazobactam, respectively. Imipenem, meropenem, and ciprofloxacin were the most active antimicrobial agents with MIC90S of 1, 1, and 0.5 mu g/ml, respectively. Nineteen isolates (7.7%) were resistant to all aminoglycosides and beta-lactam antibiotics, except carbapenems and ciprofloxacin. We are concerned about the multidrug resistance of A. baumannii in this study. PMID:9147913

  3. Genetic diversity and antimicrobial susceptibility of Nocardia species among patients with nocardiosis

    PubMed Central

    Hashemi-Shahraki, Abodolrazagh; Heidarieh, Parvin; Bostanabad, Saeed Zaker; Hashemzadeh, Mohamad; Feizabadi, Mohamad Mehdi; Schraufnagel, Dean; Mirsaeidi, Mehdi

    2015-01-01

    The aim of this multicenter study was to determine the genetic diversity and antibiotic susceptibility of clinically isolated Nocardia species. One hundred twenty-seven patients with nocardiosis were randomly selected from 5 provinces of Iran. Molecular diagnosis of Nocardia species was performed using multilocus sequence analysis of gyrase B of the β subunit of DNA topoisomerase (gyrB), and 16S rRNA and subunit A of SecA preproteintranslocase (secA1). Antimicrobial susceptibility testing was performed following the Clinical and Laboratory Standards Institute recommendations. Thirty-five N. cyriacigeorgica, 30 N. asteroides, 26 N. farcinica, 12 N. otitidiscaviarum, and 10 N. abscessus cultures were studied. All isolates were susceptible to linezolid. All isolates of N. cyriacigeorgica, N. asteroides, N. abscessus, and N. otitidiscaviarum were susceptible to trimethoprim-sulfamethoxazole, while 8% of N. farcinica isolates were resistant to this drug. All N. otitidiscaviarum isolates were highly resistant to imipenem, but N. cyriacigeorgica, N. asteroides, N. farcinica, and N. abscessus were only moderate resistant. The susceptibility patterns vary with different species of Nocardia. Resistance to trimethoprim-sulfamethoxazole in Iran is low and this drug should be first line therapy, unless drug susceptibility testing shows resistance. Linezolid also covers Nocardia well and could be a second line agent. PMID:26638771

  4. [Occurrence and antimicrobial susceptibility of Morganella morganii strains isolated from clinical samples].

    PubMed

    Zalas-Wiecek, Patrycja; Gospodarek, Eugenia; Wróblewska, Joanna

    2012-01-01

    The aim of this study was the evaluation of occurrence and antimicrobial susceptibility of M morganii rods isolated from clinical samples. This study included 201 strains isolated in the Clinical Microbiology Department of Dr. A. Jurasz University Hospital in 2008-2010. Identification to species was carried out on the basis of the results of biochemical reactions included in the tests ID 32E and VITEK2 GN. Antimicrobial susceptibility of M. morganii rods was determined by the disk-diffusion method on Mueller-Hinton II Agar. Strains of M morganii most commonly isolated from skin and soft tissue, and material taken from the urinary tract, mainly from patients of Anesthesiology and Intensive Care Unit, Department of General and Vascular Surgery and Department of General Surgery and Endocrinology. All of M morganii strains isolated during the three years were susceptible to carbapenems. We reported decrease of strains susceptible to piperacillin and chloramphenicol. In 2010 we showed a higher percentage of strains intermediate to tigecycline, compared with 2009. We observed increase in the percentage of strains resistant to cefoperazone with sulbactam and reported decrease in the percentage of strains resistant and intermediate to aminoglycosides. Extended Spectrum Beta-Lactamases were produced by 13 (6,5%) of M morganii strains. PMID:22708292

  5. Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli recovered from organic turkey farms in Germany.

    PubMed

    El-Adawy, Hosny; Ahmed, Marwa F E; Hotzel, Helmut; Tomaso, Herbert; Tenhagen, Bernd-Alois; Hartung, Joerg; Neubauer, Heinrich; Hafez, Hafez M

    2015-11-01

    The popularity of food produced from animals kept under an organic regimen has increased in recent years. In Germany, turkey meat consumption has increased. Despite several studies assessing the susceptibility of campylobacters to various antibiotics in poultry, no sufficient data exists regarding the antimicrobial resistance of campylobacters in organic-reared turkeys. This study provides information about antibiotic resistance in Campylobacter isolated from turkeys reared on organic farms in Germany. Ninety-six Campylobacter strains (41 C. jejuni and 55 C. coli) were isolated from different free-range turkey flocks. In vitro antimicrobial sensitivity testing was done using a broth microdilution test, and the presence of resistance genes to antibiotics (ciprofloxacin, tetracycline) was investigated. All Campylobacter isolates from organic turkeys (n = 96) were phenotypically sensitive to gentamicin, erythromycin, streptomycin, and chloramphenicol. In this study, the antibiotic susceptibilities of C. jejuni to ciprofloxacin, tetracycline, and naladixic acid were 56.0%, 51.3%, and 56.0%, respectively. In contrast, 44.0%, 73.0%, and 74.6% of C. coli isolates were resistant to tetracycline, ciprofloxacin, and nalidixic acid, respectively. Replacement of the Thr-86→Ile in the gyrA gene, and the presence of the tet(O) gene were the mainly identified resistance mechanisms against fluoroquinolones and tetracycline, respectively.These results also reinforce the need to develop strategies and implement specific control procedures to reduce the development of antimicrobial resistance. PMID:26371330

  6. Antimicrobial susceptibility of Streptococcus suis isolated from clinically healthy swine in Brazil

    PubMed Central

    Soares, Taíssa Cook Siqueira; Paes, Antonio Carlos; Megid, Jane; Ribolla, Paulo Eduardo Martins; Paduan, Karina dos Santos; Gottschalk, Marcelo

    2014-01-01

    Streptococcus suis is an important pathogen in the swine industry. This study is the first to report on the antimicrobial susceptibility of S. suis isolated from clinically healthy pigs in Brazil; the fourth major pork producer in the world. The antimicrobial susceptibility of 260 strains was determined by disc diffusion method. Strains were commonly susceptible to ceftiofur, cephalexin, chloramphenicol, and florfenicol, with more than 80% of the strains being susceptible to these antimicrobials. A high frequency of resistance to some of the antimicrobial agents was demonstrated, with resistance being most common to sulfa-trimethoprim (100%), tetracycline (97.69%), clindamycin (84.61%), norfloxacin (76.92%), and ciprofloxacin (61.15%). A high percentage of multidrug resistant strains (99.61%) were also found. The results of this study indicate that ceftiofur, cephalexin, and florfenicol are the antimicrobials of choice for empirical control of the infections caused by S. suis. PMID:24688177

  7. Antimicrobial susceptibility of Streptococcus suis isolated from clinically healthy swine in Brazil.

    PubMed

    Soares, Taíssa Cook Siqueira; Paes, Antonio Carlos; Megid, Jane; Ribolla, Paulo Eduardo Martins; Paduan, Karina dos Santos; Gottschalk, Marcelo

    2014-04-01

    Streptococcus suis is an important pathogen in the swine industry. This study is the first to report on the antimicrobial susceptibility of S. suis isolated from clinically healthy pigs in Brazil; the fourth major pork producer in the world. The antimicrobial susceptibility of 260 strains was determined by disc diffusion method. Strains were commonly susceptible to ceftiofur, cephalexin, chloramphenicol, and florfenicol, with more than 80% of the strains being susceptible to these antimicrobials. A high frequency of resistance to some of the antimicrobial agents was demonstrated, with resistance being most common to sulfa-trimethoprim (100%), tetracycline (97.69%), clindamycin (84.61%), norfloxacin (76.92%), and ciprofloxacin (61.15%). A high percentage of multidrug resistant strains (99.61%) were also found. The results of this study indicate that ceftiofur, cephalexin, and florfenicol are the antimicrobials of choice for empirical control of the infections caused by S. suis. PMID:24688177

  8. Clinical significance, antimicrobial susceptibility and molecular identification of Nocardia species isolated from children with cystic fibrosis.

    PubMed

    Betrán, Ana; Villuendas, M Cruz; Rezusta, Antonio; Pereira, Javier; Revillo, M José; Rodríguez-Nava, Verónica

    2016-01-01

    Nocardia is an opportunistic pathogen that causes respiratory infections in immunocompromised patients. The aim of this study was to analyze the epidemiology, clinical significance and antimicrobial susceptibility of Nocardia species isolated from eight children with cystic fibrosis. The isolated species were identified as Nocardia farcinica, Nocardia transvalensis, Nocardia pneumoniae, Nocardia veterana and Nocardia wallacei. N. farcinica was isolated in three patients and all of them presented lung affectation with a chronic colonization and pneumonia. N. farcinica showed resistance against gentamicin, tobramycin, cefotaxime, but was susceptible to trimethoprim-sulfamethoxazole and amikacin. N. transvalensis, which was isolated from two patients, showed an association with chronic colonization. N. transvalensis was resistant to tobramycin and amikacin, but susceptible to ciprofloxacin, trimethoprim-sulfamethoxazole and cefotaxime. N. veterana, N. pneumoniae and N. wallacei were isolated from three different patients and appeared in transitory lung colonization. N. veterana and N. pneumoniae were susceptible to imipenem, trimethoprim-sulfamethoxazole, amikacin, tobramycin, and cefotaxime. N. wallacei was resistant to amikacin, tobramycin, imipenem, and trimethoprim-sulfamethoxazole and susceptible to ciprofloxacin and cefotaxime. All the isolates were identified up to species level by 16S rRNA gene sequencing. The presence of Nocardia in the sputum of patients with cystic fibrosis is not always an indication of an active infection; therefore, the need for a treatment should be evaluated on an individual basis. The detection of multidrug-resistant species needs molecular identification and susceptibility testing, and should be performed for all Nocardia infections. PMID:27155949

  9. Antimicrobial susceptibilities of isolates of Staphylococcus aureus, Listeria species and Salmonella serotypes associated with poultry processing.

    PubMed

    Geornaras, I; von Holy, A

    2001-10-22

    The broth microdilution method was used to determine the activities of selected antimicrobial agents used in the South African poultry industry (danofloxacin, neomycin, chlortetracycline, oxytetracycline, tylosin and colistin) and vancomycin against bacterial isolates previously obtained from carcasses and selected equipment surfaces and environmental sources associated with poultry processing. The antimicrobial susceptibilities of 38 isolates of Staphylococcus (S.) aureus, 25 Listeria (L.) innocua, 18 L. monocytogenes, and 62 isolates belonging to six Salmonella (Salm.) serotypes (Salm. agona, Salm. blockley, Salm. enteritidis, Salm. isangi, Salm. reading and Salm. typhimurium) were determined. The most active antimicrobial agent against all the isolates tested was danofloxacin with minimum inhibitory concentrations (MICs) for 90% of the isolates (MIC90) not exceeding 0.25 and 2 microg/ml for gram-negative and gram-positive isolates, respectively. Conversely, high MICs were recorded for all the isolates tested against chlortetracycline and oxytetracycline (MIC90 range of 32 to > 512 microg/ml), except for the L. monocytogenes and Salm. enteritidis isolates (MIC range of < or = 0.5-4 microg/ml). Neomycin was found to be active against S. aureus, L. innocua, L. monocytogenes, Salm. enteritidis and Salm. isangi isolates, with MICs not exceeding 8 microg/ml. MIC ranges for tylosin and vancomycin, which were only tested against the gram-positive isolates, were from 1 to > 512 microg/ml and from 1 to 4 microg/ml, respectively. The MIC range for the remaining antimicrobial agent, colistin, which was only tested against the Salmonella isolates, was 0.5-16 microg/ml. The lack of MIC breakpoints for the antimicrobial agents used in the poultry industry did not allow for definite conclusions as to the level of resistant bacteria associated with poultry carcasses and the processing environment in this study. PMID:11759760

  10. Antimicrobial susceptibility profile of Pseudomonas spp. isolated from a swine slaughterhouse in Dourados, Mato Grosso do Sul State, Brazil.

    PubMed

    de Oliveira, Kelly M P; dos S Júlio, Péricles D; Grisolia, Alexéia B

    2013-01-01

    The present work sought to detect the presence of Pseudomonas spp. at different stages of an effluent treatment plant using the Australian system of stabilization ponds, and to determine the susceptibility of those isolates to different antimicrobials. Thirty-four isolates of Pseudomonas spp. derived from effluent treatment station water samples were collected near the transfer ducts between the ponds in November/2008 and december/2009. Among the Pseudomonas spp. isolates, 47.05 % showed susceptibility to all antimicrobials tested, 20.58 % were resistant to cefepime, and 24 % showed intermediate resistance to streptomycin. No Pseudomonas spp. isolates were found in the final pond, or in post-treatment effluents. The Pseudomonas spp. isolates did not exhibit multiresistance to the antimicrobials tested. PMID:23560791

  11. Determination of antimicrobial susceptibilities on infected urines without isolation

    NASA Technical Reports Server (NTRS)

    Picciolo, G. L.; Chappelle, E. W.; Deming, J. W.; Shrock, C. G.; Vellend, H.; Barza, M. J.; Weinstein, L. (Inventor)

    1979-01-01

    A method is described for the quick determination of the susceptibilities of various unidentified bacteria contained in an aqueous physiological fluid sample, particularly urine, to one or more antibiotics. A bacterial adenosine triphosphate (ATP) assay is carried out after the elimination of non-bacterial ATP to determine whether an infection exists. If an infection does exist, a portion of the sample is further processed, including subjecting parts of the portion to one or more antibiotics. Growth of the bacteria in the parts are determined, again by an ATP assay, to determine whether the unidentified bacteria in the sample are susceptible to the antibiotic or antibiotics under test.

  12. Effects of Quaternary-Ammonium-Based Formulations on Bacterial Community Dynamics and Antimicrobial Susceptibility

    PubMed Central

    McBain, Andrew J.; Ledder, Ruth G.; Moore, Louise E.; Catrenich, Carl E.; Gilbert, Peter

    2004-01-01

    Quaternary ammonium compounds (QACs) are widely used as adjuncts to hygiene in domestic cleaning products. Current concern that the increased use of such biocides in consumer products might contribute to the emergence of antibiotic resistance has led us to examine the effects of a QAC-containing domestic cleaning fluid on the population dynamics and antimicrobial susceptibility of domestic sink drain biofilm communities. QAC susceptibilities of numerically dominant, culturable drain bacteria (15 genera, 17 species) were determined in vitro before and after repeated QAC exposure (14 passages). A fully characterized drain microcosm was then exposed to short-term (12 days) and long-term (3 months) dosing with a QAC-containing domestic detergent (QD). QAC exposure of isolated cultures caused both increases (three species) and circa twofold decreases (six species) in QAC susceptibility. The susceptibility of Ralstonia sp. was considerably decreased following 14 consecutive QAC passages. Control drain microcosm biofilms maintained dynamic stability, as evidenced by culture and denaturing gradient gel electrophoresis (DGGE) analysis. Bacterial population densities were largely unaffected during short-term exposure to use levels of QD, although 50% QD caused circa 10-fold viability reductions. DGGE analysis supported these observations; identified the major microcosm genera as Pseudomonas, Pseudoalteromonas, Erwinia, and Enterobacter, and showed that aeromonads increased in abundance under 10 to 50% QD. Long-term exposure of the microcosms to QD did not significantly alter the pattern of antimicrobial susceptibility. These data demonstrate the recalcitrance of domestic drain biofilms toward QAC and that although repeated QAC exposure of drain isolates in pure culture results in susceptibility change in some test bacteria, such changes do not necessarily occur within complex communities. PMID:15184143

  13. Antimicrobial Susceptibility Patterns of Brachyspira Species Isolated from Swine Herds in the United States.

    PubMed

    Mirajkar, Nandita S; Davies, Peter R; Gebhart, Connie J

    2016-08-01

    Outbreaks of swine dysentery, caused by Brachyspira hyodysenteriae and the recently discovered "Brachyspira hampsonii," have reoccurred in North American swine herds since the late 2000s. Additionally, multiple Brachyspira species have been increasingly isolated by North American diagnostic laboratories. In Europe, the reliance on antimicrobial therapy for control of swine dysentery has been followed by reports of antimicrobial resistance over time. The objectives of our study were to determine the antimicrobial susceptibility trends of four Brachyspira species originating from U.S. swine herds and to investigate their associations with the bacterial species, genotypes, and epidemiological origins of the isolates. We evaluated the susceptibility of B. hyodysenteriae, B. hampsonii, Brachyspira pilosicoli, and Brachyspira murdochii to tiamulin, valnemulin, doxycycline, lincomycin, and tylosin by broth microdilution and that to carbadox by agar dilution. In general, Brachyspira species showed high susceptibility to tiamulin, valnemulin, and carbadox, heterogeneous susceptibility to doxycycline, and low susceptibility to lincomycin and tylosin. A trend of decreasing antimicrobial susceptibility by species was observed (B. hampsonii > B. hyodysenteriae > B. murdochii > B. pilosicoli). In general, Brachyspira isolates from the United States were more susceptible to these antimicrobials than were isolates from other countries. Decreased antimicrobial susceptibility was associated with the genotype, stage of production, and production system from which the isolate originated, which highlights the roles of biosecurity and husbandry in disease prevention and control. Finally, this study also highlights the urgent need for Clinical and Laboratory Standards Institute-approved clinical breakpoints for Brachyspira species, to facilitate informed therapeutic and control strategies. PMID:27252458

  14. Isolation of Helicobacter pylori in gastric mucosa and susceptibility to five antimicrobial drugs in Southern chile

    PubMed Central

    Otth, Laura; Wilson, Myra; Fernández, Heriberto; Otth, Carola; Toledo, Claudio; Cárcamo, Victoria; Rivera, Paula; Ruiz, Luis

    2011-01-01

    Helicobacter pylori colonizes more than 50% of the world population thus, it is considered an important cause of gastric cancer. The aim of this study was to determine the isolation frequency of H. pylori in Southern Chile from patients with symptomatology compatible with gastritis or gastric ulcer and to correlate these findings with demographic parameters of infected patients and the susceptibility profiles of the isolated strains to the antimicrobial drugs used in the eradication treatments. A total of 240 patients were enrolled in the study. Each gastric biopsy was homogenized and seeded onto blood agar plates containing a selective antibiotics mixture (DENT supplement). Plates were incubated at 37° C in a microaerophilic environment for five days. The susceptibility profiles to amoxicillin, ciprofloxacin, clarithromycin, tetracycline and metronidazole were determined using the E-test method. H. pylori was isolated from 99 patients (41.3%) with slightly higher frequency in female (42% positive cultures) than male (40.2% positive cultures). With regard to age and educational level, the highest isolation frequencies were obtained in patients between 21–30 (55%) and 41–50 (52.6%) years old, and patients with secondary (43.9%) and university (46.2%) educational levels. Nineteen (21.6%) strains showed resistance to at least one antimicrobial drug. Tetracycline was the most active antimicrobial in vitro, whereas metronidazole was the less active. One strain (5.3%) showed resistance to amoxicillin, clarithomycin and metronidazole, simultaneously. PMID:24031652

  15. Salmonella Prevalence and Antimicrobial Susceptibility Among Dairy Farm Environmental Samples Collected in Texas.

    PubMed

    Rodriguez-Rivera, Lorraine D; Cummings, Kevin J; Loneragan, Guy H; Rankin, Shelley C; Hanson, Devin L; Leone, William M; Edrington, Thomas S

    2016-04-01

    Dairy cattle are a reservoir of several Salmonella serovars that are leading causes of human salmonellosis. The objectives of this study were to estimate the environmental prevalence of Salmonella on dairy farms in Texas and to characterize the antimicrobial susceptibility of the isolates. Eleven dairy farms throughout Texas were sampled from August through October 2013, using a cross-sectional approach. Samples were collected from four locations within each farm (hospital pen, maternity pen, cow housing area, and calf housing area), and feces were collected from cull cows as available. Environmental and fecal samples were processed for Salmonella, and isolates were tested for susceptibility to 15 antimicrobial agents. Serovar characterization was performed on a subset of these isolates. Salmonella was isolated from 67.0% (236/352) of the environmental samples and 64.2% (43/67) of the cull cow fecal samples. Environmental samples from the maternity pen were significantly more likely to be Salmonella positive than samples from the cow and calf housing areas. Multidrug resistance was evident in 11.9% (27/226) of environmental isolates and 19.5% (8/41) of fecal isolates. Salmonella isolates from the calf housing area and maternity pen were significantly more likely to be multidrug resistant (MDR) than isolates from the cow housing area. The most common serovars found among the MDR isolates were Newport, Muenchen, and Typhimurium. These results help provide a focus for efforts to mitigate the burden of antimicrobial-resistant Salmonella at the preharvest level. PMID:26954516

  16. Antimicrobial susceptibility pattern of extended-spectrum beta- lactamase producing Klebsiella pneumoniae clinical isolates in an Indian tertiary hospital

    PubMed Central

    Singh, Amit Kumar; Jain, Sonali; Kumar, Dinesh; Singh, Ravinder Pal; Bhatt, Hitesh

    2015-01-01

    Objective: There is an increased prevalence of extended-spectrum beta-lactamase producing Klebsiella pneumoniae (ESBL-KP) worldwide including India, which is a major concern for the clinicians, especially in intensive care units and pediatric patients. This study aims to determine the prevalence of ESBL-KP and antimicrobial sensitivity profile to plan a proper hospital infection control program to prevent the spread of resistant strains. Methods: KP isolates obtained from various clinical samples were evaluated to detect the production of ESBL by phenotypic methods. Antimicrobial susceptibility profile was also determined of all the isolates. Findings: Of 223 nonduplicate isolates of K. pneumoniae, 114 (51.1%) were ESBL producer and antimicrobial susceptibility profile showed the isolates were uniformly sensitive to imipenem and highly susceptible to beta-lactamase inhibitor combination drugs (67–81%) and aminoglycosides (62–76%), but less susceptible to third generation cephalosporins (14–24%) and non-β-lactam antibiotics such as nitrofurantoin (57%), fluoroquinolones (29–57%), piperacillin (19–23%), and aztreonam (15–24%). Conclusion: This study found that beta-lactamase inhibitor combinations are effective in treatment of such infections due to ESBL-KP thus these drugs should be a part of the empirical therapy and carbapenems should be used when the antimicrobial susceptibility tests report resistance against inhibitors combinations. PMID:26312255

  17. In vitro assessment of the antimicrobial susceptibility of caprine isolates of Mycoplasma mycoides subsp. capri.

    PubMed

    Paterna, A; Tatay-Dualde, J; Amores, J; Prats-van der Ham, M; Sánchez, A; de la Fe, C; Contreras, A; Corrales, J C; Gómez-Martín, Á

    2016-08-01

    The minimum inhibitory concentration (MIC) and minimum mycoplasmacidal concentration (MMC) of 17 antimicrobials against 41 Spanish caprine isolates of Mycoplasma mycoides subsp. capri (Mmc) obtained from different specimens (milk, external auricular canal and semen) were determined using a liquid microdilution method. For half of the isolates, the MIC was also estimated for seven of the antimicrobials using an epsilometric test (ET), in order to compare both methods and assess the validity of ET. Mutations in genes gyrA, gyrB, parC and parE conferring fluoroquinolone resistance, which have been recently described in Mmc, were investigated using PCR. The anatomical origin of the isolate had no effect on its antimicrobial susceptibility. Moxifloxacin and doxycycline had the lowest MIC values. The rest of the fluoroquinolones studied (except norfloxacin), together with tylosin and clindamycin, also had low MIC values, although the MMC obtained for clindamycin was higher than for the other antimicrobials. For all the aminoglycosides, spiramycin and erythromycin, a notable level of resistance was observed. The ET was in close agreement with broth microdilution at low MICs, but not at intermediate or high MICs. The analysis of the genomic sequences revealed the presence of an amino acid substitution in codon 83 of the gene gyrA, which has not been described previously in Mmc. PMID:27387734

  18. Development of Similar Broth Microdilution Methods to Determine the Antimicrobial Susceptibility of Flavobacterium columnare and F. psychrophilum.

    PubMed

    Gieseker, Charles M; Crosby, Tina C; Mayer, Tamara D; Bodeis, Sonya M; Stine, Cynthia B

    2016-03-01

    Flavobacterium columnare and F. psychrophilum are major fish pathogens that cause diseases that may require antimicrobial therapy. Choice of appropriate treatment is dependent upon determining the antimicrobial susceptibility of isolates. Therefore we optimized methods for broth microdilution testing of F. columnare and F. psychrophilum to facilitate standardizing an antimicrobial susceptibility test. We developed adaptations to make reproducible broth inoculums and confirmed the proper incubation time and media composition. We tested the stability of potential quality-control bacteria and compared test results between different operators. Log phase occurred at 48 h for F. columnare and 72-96 h for F. psychrophilum, confirming the test should be incubated at 28°C for approximately 48 h and at 18°C for approximately 96 h, respectively. The most consistent susceptibility results were achieved with plain, 4-g/L, dilute Mueller-Hinton broth supplemented with dilute calcium and magnesium. Supplementing the broth with horse serum did not improve growth. The quality-control strains, Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658, yielded stable minimal inhibitory concentrations (MIC) against all seven antimicrobials tested after 30 passes at 28°C and 15 passes at 18°C. In comparison tests, most MICs of the isolates agreed 100% within one drug dilution for ampicillin, florfenicol, and oxytetracycline. The agreement was lower with the ormetoprim-sulfdimethoxine combination, but there was at least 75% agreement for all but one isolate. These experiments have provided methods to help standardize antimicrobial susceptibility testing of these nutritionally fastidious aquatic bacteria. Received June 24, 2015; accepted October 2, 2015. PMID:26949840

  19. Molecular characterization and antimicrobial susceptibility of Clostridium difficile isolated from rabbits raised for meat production.

    PubMed

    Drigo, Ilenia; Mazzolini, Elena; Bacchin, Cosetta; Tonon, Elena; Puiatti, Cinzia; Bano, Luca; Spigaglia, Patrizia; Barbanti, Fabrizio; Agnoletti, Fabrizio

    2015-12-31

    Clostridium difficile is an important cause of enteric disease in humans and animals. Recent studies demonstrated a genetic overlap between C. difficile isolated from animals and humans suggesting animals as possible reservoir for human pathogenic strains. This study was a preliminary investigation on the occurrence of C. difficile in rabbits raised in industrial holdings for food production and aimed to characterise isolates and estimate their antimicrobial susceptibility. C. difficile isolates were characterized by toxin profiles, toxinotyping and PCR-ribotyping. The MICs of six antibiotics were determined using E-test. Between 2007 and 2013, 285 industrial holdings (representing 40% of the national census) submitted rabbits to our laboratory for diagnostic purposes, among these holdings, groups of three to five post-weaned rabbits were sampled once by convenience. 1279 samples of caecal content were collected. The overall isolation rate of C. difficile from the enteric specimen was 3% (38/1279), with no difference among animals affected or not by enteric disorders. Among isolates 66% (25/38) were toxigenic. Sixteen different PCR-ribotypes (RTs) were identified. Among the toxigenic strains RT-014/020, RT-078 and RT-012 were found in at least three rabbit holdings. According to the ECOFF threshold, 82% (31/38) C. difficile isolates displayed a reduced susceptibility to at least one and 18% (7/38) to three tested antimicrobials. Rabbits are colonized by heterogeneous C. difficile ribotypes many of which are commonly isolated in humans. One third of isolates displayed a reduced susceptibility to MTZ, the first choice antimicrobial for human CDI treatment. According to our findings rabbits are a potential source of C. difficile for humans. PMID:26507420

  20. Epidemiology and antimicrobial susceptibilities of wound isolates of obligate anaerobes from combat casualties.

    PubMed

    White, Brian K; Mende, Katrin; Weintrob, Amy C; Beckius, Miriam L; Zera, Wendy C; Lu, Dan; Bradley, William; Tribble, David R; Schnaubelt, Elizabeth R; Murray, Clinton K

    2016-02-01

    Data from recent conflicts related to war wounds and obligate anaerobes are limited. We define the epidemiology and antimicrobial susceptibility of obligate anaerobes from Iraq and Afghanistan casualties (6/2009-12/2013), as well as their association with clinical outcomes. Susceptibility against eleven antibiotics (7 classes) was tested. Overall, 59 patients had 119 obligate anaerobes identified (83 were first isolates). Obligate anaerobes were isolated 7-13 days post-injury, primarily from lower extremity wounds (43%), and were largely Bacteroides spp. (42%) and Clostridium spp. (19%). Patients with pelvic wounds were more likely to have Bacteroides spp. and concomitant resistant gram-negative aerobes. Seventy-three percent of isolates were resistant to ≥1 antimicrobials. Bacteroides spp. demonstrated the most resistance (16% of first isolates). Patients with resistant isolates had similar outcomes to those with susceptible strains. Serial recovery of isolates occurred in 15% of patients and was significantly associated with isolation of Bacteroides spp., along with resistant gram-negative aerobes. PMID:26607420

  1. Occurrence and antimicrobial susceptibility of Listeria monocytogenes isolated from brined white cheese in Jordan.

    PubMed

    Osaili, Tareq M; Al-Nabulsi, Anas A; Taha, Mohammad H; Al-Holy, Murad A; Alaboudi, Akram R; Al-Rousan, Walid M; Shaker, Reyad R

    2012-09-01

    Listeria monocytogenes is a serious foodborne pathogen that has been isolated from different dairy food products. Several foodborne outbreaks of listeriosis have been associated with consumption of cheese. The aims of this study were to determine the occurrence of L. monocytogenes and Listeria spp. in brined white cheese (BWC) sold in Jordan, and to determine the susceptibility of isolated L. monocytogenes to antimicrobials. Three hundred and fifty samples of 5 different types of BWC (akkawi, boiled, halloumi, pasteurized, and shellal) were collected from a local market in Jordan. The ISO (11290-1) procedure was followed for isolation and identification of Listeria spp. from cheese samples and a polymerase chain reaction (PCR) technique was used for confirmation of L. monocytogenes isolates. The VITEK2 automated system was used for testing antimicrobial susceptibility of L. monocytogenes isolates. The overall prevalence of Listeria spp. in cheese sample was 27.1%. L. monocytogenes was isolated from 39 (11.1%) samples. Other isolated species were L. grayi (6.9%), L. innocua (2%), L. ivanovii (4%), L. seeligeri (2%), and L. welshimeri (0.3%). The pH values and salt concentrations of L. monocytogenes positive cheese samples ranged from 5.10 to 6.32 and 5.64 to 13.16, respectively. L. monocytogenes isolates were sensitive or intermediate susceptible to imipenem, gentamicin, linezolid, teicoplanin, vancomycin, fusidic acid, trimethoprim/sulfamethoxazole, benzylpenicillin, ciprofloxacin, erythromycin, tetracycline, and rifampicin, but resistant to fosfomycin, oxacillin, and clindamycin. PMID:22897495

  2. Serotypes and antimicrobial susceptibility of Salmonella spp. isolated from farm animals in China

    PubMed Central

    Kuang, Xiuhua; Hao, Haihong; Dai, Menghong; Wang, Yulian; Ahmad, Ijaz; Liu, Zhenli; Zonghui, Yuan

    2015-01-01

    Salmonella spp. can indirectly infect humans via transfer from animals and animal-derived food products, and thereby cause potentially fatal diseases. Therefore, gaining an understanding of Salmonella infection in farm animals is increasingly important. The aim of this study was to identify the distribution of serotypes in Salmonella samples isolated from chickens (n = 837), pigs (n = 930), and dairy cows (n = 418) in central China (Henan, Hubei, and Hunan provinces) in 2010–2011, and investigate the susceptibility of strains to antimicrobial agents. Salmonella isolates were identified by PCR amplification of the invA gene, serotypes were determined by using a slide agglutination test for O and H antigens, and susceptibility to 24 antimicrobials was tested using the agar dilution method. In total, 248 Salmonella strains were identified: 105, 105, and 38 from chickens, dairy cows, and pigs, respectively. Additionally, 209 strains were identified in diseased pigs from the Huazhong Agricultural University veterinary hospital. Among these 457 strains, the dominant serotypes were Typhimurium in serogroup B, IIIb in serogroup C, and Enteritidis in serogroup D. In antimicrobial susceptibility tests, 41.14% of Salmonella spp. were susceptible to all antimicrobial agents, 48.14% were resistant to at least one, and 34.72% were resistant to more than three classes. Strains were highly resistant to sulfamethoxazole-trimethoprim (39.61%), nalidixic acid (39.17%), doxycycline (28.22%), and tetracycline (27.58%). Resistance to cephalosporins and fluoroquinolones ranged from 5.25 to 7.44% and 19.04 to 24.51%, respectively. Among penicillin-resistant and cephalosporin-resistant strains, 25 isolates produced extended-spectrum β-lactamases (ESBLs). The multidrug-resistant and ESBL-producing Salmonella strains identified in healthy animals here will present a challenge for veterinary medicine and farm animal husbandry, and could also pose a threat to public health. The level of

  3. Susceptibility testing of Propionibacterium acnes comparing agar dilution with E test.

    PubMed Central

    Smith, M A; Alperstein, P; France, K; Vellozzi, E M; Isenberg, H D

    1996-01-01

    Propionibacterium acnes has been identified as a significant agent of nosocomial infections, including endophthalmitis. Data concerning susceptibility of P. acnes to newer beta-lactam antibiotics and fluoroquinolones are limited. Recent reports suggest that quinolones have activity against these organisms sufficient to warrant further study. We undertook a study to select appropriate antimicrobial agents for use in a rabbit model of P. acnes endophthalmitis. We compared the antibiotic susceptibilities of P. acnes by using the National Committee for Clinical Laboratory Standards method of agar dilution with the E test. Thirteen clinical isolates obtained from eye specimens and three American Type Culture Collection control strains were tested against 14 antibiotics. All the clinical isolates were susceptible by both methods to piperacillin, piperacillin-tazobactam, ampicillin-sulbactam, ticarcillin-clavulanate, cefotaxime, cefotetan, ceftriaxone, cefoxitin, and imipenem in addition to clindamycin but were resistant to metronidazole. The clinical P. acnes isolates also displayed high-level susceptibility to ciprofloxacin, sparfloxacin, and ofloxacin. Almost all the P. acnes strains demonstrated E-test MICs within 2 dilutions of the MICs observed by the agar dilution method. Those few strains for which discrepancies were noted exhibited E-test susceptibilities three- to fivefold dilutions lower than the agar dilution method susceptibilities but only with ampicillin-sulbactam, ticarcillin-clavulanate, and/or clindamycin. On the basis of our study, all of clinical eye isolates were susceptible to these newer antimicrobial agents and the two methods demonstrated similar susceptibility patterns. PMID:8815076

  4. USDA Data on Antimicrobial Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing remains an important tool as investigators devise ways to arrest the development of antimicrobial resistance, particularly in food borne bacteria. In 1996, the Food and Drug Administration (FDA) initiated the National Antimicrobial Resistance Monitoring System -...

  5. Antimicrobial susceptibility of foodborne pathogens in organic or natural production systems: an overview.

    PubMed

    Jacob, Megan E; Fox, James Trent; Reinstein, Shelby L; Nagaraja, T G

    2008-12-01

    Organic and natural food production systems are increasing in popularity, at least partially because consumers perceive that these niche markets provide healthier and safer food products. One major difference between these niche markets and conventional production systems is the use of antimicrobials. Because antimicrobial agents exert selective pressures for antimicrobial resistance, relating antimicrobial susceptibility of foodborne bacteria to niche market production systems is of interest. Other differences between production systems might also influence the susceptibility of foodborne pathogens. The objective of this review is to compare the impact of food animal production systems on the antimicrobial susceptibility of common foodborne bacterial pathogens. Studies comparing the susceptibility of such pathogens were diverse in terms of geographic location, procedures, species of bacteria, and antimicrobials evaluated; thus, it was difficult to draw conclusions. The literature is highly variable in terms of production type and practices and susceptibility associations, although few studies have compared truly organic and conventional practices. When statistical associations were found between production type and minimum inhibitory concentrations or percentage of isolates resistant for a particular pathogen, the isolates from conventionally reared animals/products were more commonly resistant than the comparison group (organic, antibiotic free, etc.). Therefore, further studies are needed to better assess public health consequences of antimicrobial resistance and food animal production systems, specifically organic or natural versus conventional. PMID:18847380

  6. Antimicrobial susceptibility of Staphylococcus aureus and Staphylococcus pseudintermedius isolated from various animals.

    PubMed

    Rubin, Joseph E; Ball, Katherine R; Chirino-Trejo, Manuel

    2011-02-01

    This study characterized the antimicrobial susceptibility of 221 Staphylococcus aureus isolated from various species, and 60 canine Staphylococcus pseudintermedius isolated from 1986 through 2000 at the Western College of Veterinary Medicine (WCVM). Resistance of S. aureus was most common to penicillin (31%) and tetracycline (14%); resistance of S. pseudintermedius to penicillin was present in 8% and to tetracycline in 34% of isolates. Resistance to trimethoprim/sulfamethoxazole was only seen among S. pseudintermedius, and there was no resistance to amoxicillin/clavulanate, ampicillin/sulbactam, cephalothin, amikacin, gentamicin, enrofloxacin, chloramphenicol, or rifampin among any isolate. Inducible clindamycin resistance was found in both S. aureus and S. pseudintermedius, highlighting the need for careful interpretation of culture and susceptibility test results. There were significant differences in the minimum inhibitory concentrations of penicillin, ciprofloxacin, enrofloxacin, clindamycin, erythromycin, chloramphenicol, and tetracycline between avian, bovine, equine, and porcine isolates. PMID:21532820

  7. Species-Specific Difference in Antimicrobial Susceptibility Among Viridans Group Streptococci

    PubMed Central

    Chun, Sejong; Huh, Hee Jae

    2015-01-01

    Background Viridans group streptococci (VGS) are both commensal microbes and potential pathogens. Increasing resistance to penicillin in VGS is an ongoing issue in the clinical environment. We investigated the difference in susceptibility and resistance to penicillin among various VGS species. Methods In total 1,448 VGS isolated from various clinical specimens were analyzed over a two-yr period. Identification and antimicrobial susceptibility test was performed by the automated VITEK 2 system (bioMerieux, France) or the MicroScan MICroSTREP system (Siemens, Germany). Results Among the 1,448 isolates, 412 were isolated from blood (28.4%). Streptococcus mitis group was the most frequently isolated (589 isolates, 40.7%), followed by the S. anginosus group (290 isolates, 20.0%), S. sanguinis group (179 isolates, 12.4%) and S. salivarius group (57 isolates, 3.9%). In total, 314 isolates could not be identified up to the species level. The overall non-susceptibility to penicillin was observed to be 40.0% (resistant, 11.2% and intermediately resistant, 28.8%) with uneven distribution among groups; 40.2% in S. sanguinis group (resistant, 5.0% and intermediately resistant, 35.2%), 60.3% in S. mitis group (resistant, 20.9% and intermediately resistant, 39.4%), 78.9% in S. salivarius group (resistant, 8.8% and intermediately resistant, 70.1%), and 6.2% in S. anginosus group (resistant, 1.7% and intermediately resistant, 4.5%). Conclusions Antimicrobial resistance patterns towards penicillin show differences among various VGS; this should be considered while devising an effective antimicrobial treatment against VGS. PMID:25729722

  8. Antimicrobial susceptibility of Swedish, Norwegian and Danish isolates of Clostridium perfringens from poultry, and distribution of tetracycline resistance genes.

    PubMed

    Johansson, A; Greko, C; Engström, B E; Karlsson, M

    2004-04-19

    This study was undertaken to determine the in vitro susceptibility of Clostridium perfringens, isolated from poultry to antimicrobials used in poultry production. The minimal inhibitory concentration (MIC) of eight antimicrobials, including the ionophoric coccidiostat narasin, was determined for 102 C. perfringens isolates, 58 from Sweden, 24 from Norway and 20 from Denmark. Susceptibility to each antimicrobial compound was determined by broth microdilution. The isolates were obtained from broilers (89), laying hens (9) and turkeys (4), affected by necrotic enteritis (NE) or by C. perfringens associated hepatitis (CPH), and from healthy broilers. All strains, regardless of origin, proved inherently susceptible to ampicillin, narasin, avilamycin, erythromycin and vancomycin. A low frequency of resistance to virginiamycin and bacitracin was also found. Resistance to tetracycline was found in strains isolated in all three countries; Sweden (76%), Denmark (10%) and Norway (29%). In 80% of the tetracycline-resistant isolates, the two resistance genes tetA(P) and tetB(P) were amplified by PCR whereas in 20% only the tetA(P) gene was detected. No tetM gene amplicon was obtained from any of the tetracycline-resistant isolates. The uniform susceptibility to narasin revealed in this study shows that the substance can still be used to control clostridiosis. In this study, C. perfringens also showed a low degree of resistance to most other antimicrobials tested. Despite the small amounts of tetracycline used in poultry, a considerable degree of resistance to tetracycline was found in C. perfringens isolates from Swedish broilers. PMID:15066727

  9. Antimicrobial susceptibility and pathogenic genes of Staphylococcus aureus isolated from the oral cavity of patients with periodontitis

    PubMed Central

    2015-01-01

    Purpose The goal of this study was to characterize the patterns of antimicrobial resistance and virulence genes in samples of Staphylococcus aureus (S. aureus) isolated from periodontitis patients. Methods From July 2015 to August 2015, oral saliva was collected from a total of 112 patients diagnosed with periodontitis, including 80 outpatients in dental hospitals and 32 patients in dental clinics located in Seoul and Cheonan. The samples were subjected to a susceptibility test to evaluate the prevalence of antimicrobial resistance, and the pathogenic factors and antimicrobial resistance factors in the DNA of S. aureus were analyzed using polymerase chain reaction. Results A susceptibility test against 15 antimicrobial agents showed that 88% of cultures were resistant to ampicillin, 88% to penicillin, and 2% to oxacillin. Resistance to at least two drugs was observed in 90% of cultures, and the most common pattern of multidrug resistance was to ampicillin and penicillin. Enterotoxins were detected in 65.9% of samples. The cell hemolysin gene hld was detected in 100% of cultures and hla was detected in 97.6% of samples. All strains resistant to penicillin and ampicillin had the blaZ gene. The aph(3′)IIIa gene, which encodes an aminoglycoside modifying enzyme, was detected in 46.3% of samples. Conclusions In the treatment of oral S. aureus infections, it is important to identify the pathogenic genes and the extent of antimicrobial resistance. Furthermore, it is necessary to study patterns of antimicrobial resistance and cross-infection in the context of periodontological specialties in which antimicrobials are frequently used, such as maxillofacial surgery, where the frequency of antimicrobial use for minor procedures such as implant placement is increasing. PMID:26734493

  10. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities.

    PubMed

    Liu, Ming-Che; Tsai, Yi-Lin; Huang, Yi-Wei; Chen, Hsing-Yu; Hsueh, Po-Ren; Lai, Szu-Yu; Chen, Li-Chia; Chou, Yi-Hwa; Lin, Wen-Yuan; Liaw, Shwu-Jen

    2016-01-01

    Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs). Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2-64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia. PMID:27159404

  11. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities

    PubMed Central

    Huang, Yi-Wei; Chen, Hsing-Yu; Hsueh, Po-Ren; Lai, Szu-Yu; Chen, Li-Chia; Chou, Yi-Hwa; Lin, Wen-Yuan; Liaw, Shwu-Jen

    2016-01-01

    Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs). Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2–64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia. PMID:27159404

  12. Antimicrobial susceptibility of coagulase-negative staphylococci isolated from bovine milk samples.

    PubMed

    Sampimon, O C; Lam, T J G M; Mevius, D J; Schukken, Y H; Zadoks, R N

    2011-05-12

    The aim of this study was to examine whether antimicrobial resistance profiles of coagulase-negative Staphylococcus (CNS) species isolated from milk of dairy cows differed between bacterial species, and to compare results obtained by phenotypic and genotypic profiling of resistance to penicillin, oxacillin and macrolide-lincosamide (ML) antibiotics. Of 170 CNS isolates, 83 (48.8%) were phenotypically susceptible to all antimicrobial agents tested in minimum inhibitory concentration (MIC) assays, 40.6% expressed resistance to a single compound or a single class of compounds, and 10.6% to multiple drug classes. Nine percent, 68%, 19%, 4% and 1% of isolates were negative for all resistance genes tested by PCR or positive for one, two, three or four resistance genes, respectively. Phenotypic resistance and detection of resistance genes other than blaZ were relatively rare in Staphylococcus chromogenes, which was the most common CNS species (36% of 170 genotypically identified isolates). In Staphylococcus epidermidis, which was the second most common CNS species (14% of isolates), phenotypic penicillin resistance was significantly more common than in other CNS species. Almost half of the S. epidermidis isolates carried multiple resistance genes and 30% carried the methicillin resistance gene mecA. Survival analysis using MIC values showed significant associations between phenotypic and genotypic resistance profiles. We conclude that CNS species from bovine milk differ significantly in phenotypic and genotypic antimicrobial resistance profiles, which has implications for treatment and management decisions. PMID:21333468

  13. Antimicrobial susceptibility of Clostridium difficile isolated from food animals on farms.

    PubMed

    Thitaram, S N; Frank, J F; Siragusa, G R; Bailey, J S; Dargatz, D A; Lombard, J E; Haley, C A; Lyon, S A; Fedorka-Cray, P J

    2016-06-16

    Clostridium difficile is commonly associated with a spectrum of disease in humans referred to as C. difficile-associated disease (CDAD) and use of antimicrobials is considered a risk factor for development of disease in humans. C. difficile can also inhabit healthy food animals and transmission to humans is possible. As a result of the complexity and cost of testing, C. difficile is rarely tested for antimicrobial susceptibility. A total of 376 C. difficile strains (94 each from swine and dairy feces, and 188 from beef cattle feces) were isolated from healthy food animals on farms during studies conducted by the National Animal Health Monitoring System. Using the Etest (AB Biodisk, Solna, Sweden), samples were tested for susceptibility to nine antimicrobials implicated as risk factors for CDAD (linezolid, amoxicillin-clavulanic acid, ampicillin, clindamycin, erythromycin, levofloxacin, metronidazole, rifampicin, and vancomycin). Vancomycin was active against all isolates of C. difficile (MIC90=3.0μg/ml) while almost all isolates (n=369; 98.1%) were resistant to levofloxacin. With the exception of vancomycin, resistance varied by animal species as follows: linezolid (8.5% resistance among swine versus 2.1 and 1.1% resistance among dairy and beef, respectively), clindamycin (56.4% resistance among swine versus 80% and 90.9% resistance among dairy and beef, respectively), and rifampicin (2.1% and 0% resistance among swine and dairy cattle isolates, respectively versus 14.3% resistance among beef isolates). Regardless of species, multiple drug resistance was observed most often to combinations of clindamycin and levofloxacin (n=195; 51.9%) and ampicillin, clindamycin and levofloxacin (n=41; 10.9%). The reason for the variability of resistance between animal species is unknown and requires further research. PMID:27043382

  14. Genotypically Different Clones of Staphylococcus aureus Are Diverse in the Antimicrobial Susceptibility Patterns and Biofilm Formations

    PubMed Central

    Atshan, Salman Sahab; Nor Shamsudin, Mariana; Lung, Leslie Than Thian; Sekawi, Zamberi; Pei Pei, Chong; Karunanidhi, Arunkumar; Jeevajothi Nathan, Jayakayatri; Mateg Ali, Alreshidi; Ghaznavi-Rad, Ehsanollah; Abduljaleel, Salwa A.; Awang Hamat, Rukman

    2013-01-01

    This study evaluated whether genotypically different clinical isolates of S. aureus have similar susceptibilities to individual antibiotics. It further aims to check the impact of biofilm on the in vitro activity of vancomycin, daptomycin, linezolid, and tigecycline against S. aureus clones. The study used a total of 60 different clinical MSSA and MRSA isolates. Susceptibilities were performed in planktonic cultures by macrobroth dilution and epsilon-test (E test) system. Biofilm production was determined using an adherent plate assay. The efficacy of antimicrobial activities against biofilms formation was checked using confocal laser scanning microscopy (CLSM). The study found that similar and different spa, MLST, and SCCmec types displayed high variation in their susceptibilities to antibiotics with tigecycline and daptomycin being the most effective. The biofilms were found resistant to high concentrations of most antibiotics tested with daptomycin being the most effective drug used in adhesive biofilms. A considerable difference exists among similar and various clone types against antibiotics tested. This variation could have contributed to the degree of virulence even within the same clonal genotype and enhanced heterogeneity in the infection potential. Thus, the development of a rapid and precise identification profile for each clone in human infections is important. PMID:24455699

  15. Effect of antimicrobial peptides on colistin-susceptible and colistin-resistant strains of Klebsiella pneumoniae and Enterobacter asburiae.

    PubMed

    Kádár, Béla; Kocsis, Béla; Kristof, Katalin; Tóth, Ákos; Szabó, Dóra

    2015-12-01

    In this study susceptibility to different antimicrobial peptides was investigated on colistin-susceptible and colistin-resistant identical pulsotype strains of KPC-2 producing Klebsiella pneumoniae ST258 as well as colistin-susceptible and colistin-resistant Enterobacter asburiae strains isolated from clinical samples. In our test, bacteria were exposed to 50 mg/ml lactoferrin, lysozyme and protamine - cationic antimicrobial peptides belonging to innate immune system and having structural similarity to polymyxins - in separate reactions. After 18 hours incubation of colonies were counted. 40% of colistin-resistant K. pneumoniae strains and 97% of colistin-susceptible counterpart strains were lysed by protamine whereas 87% and 100% colony forming unit decrease by lysozyme was seen, respectively. In the case of colistin-resistant E. asburiae strains 1 log10 cell count increase were observed after treatment with lysozyme and 1.56 log10 after lactoferrin exposure compared to the initial number whereas the colistin-susceptible showed no relevant cell count increase. Our findings suggest that acquired colistin-resistance in Enterobacteriaceae is associated with tolerance against antimicrobial peptides. PMID:26689883

  16. Enteric fever imported to the Czech Republic: epidemiology, clinical characteristics and antimicrobial susceptibility.

    PubMed

    Trojánek, Milan; Dědičová, Daniela; Žemličková, Helena; Jakubů, Vladislav; Malíková, Eliška; Reisingerová, Marie; Gabrielová, Alice; Papagiannitsis, Costas C; Hrabák, Jaroslav; Horová, Blanka; Urbášková, Pavla; Marešová, Vilma; Stejskal, František

    2015-05-01

    The aim of this study was to describe epidemiological and clinical characteristics of imported enteric fever in Czech travellers and to determine the antimicrobial susceptibility of isolated strains. Retrospective descriptive study included adult patients treated with enteric fever at Hospital Na Bulovce during January 2004-December 2012. A case of typhoid or paratyphoid fever was defined as isolation of Salmonella Typhi or Paratyphi from blood or stool. During the study period, there have been diagnosed 19 cases of enteric fever (12 males and 7 females) with age median of 30 years; 14 cases were caused by Salmonella Typhi and 5 cases by S. Paratyphi A. The infection has been acquired in South Asia (16 patients; 84.2 %), in Africa (Egypt, Angola) in two cases (10.5 %), and in Mexico (1; 5.3 %). Symptoms included fever (all patients), diarrhoea (16 cases; 84.2 %), headache (9; 47.4 %), and abdominal pain (7; 36.8 %). Seventeen patients (89.5 %) were treated with fluoroquinolones; however, the treatment failure was observed in seven of them (41.2 %). Decreased ciprofloxacin susceptibility was detected in eight strains (66.7 %), and one strain (8.3 %) was multidrug resistant. Sequence analysis of quinolone resistance-determining regions (QRDR) of the gyrA gene revealed the presence of amino acid substitutions in all tested isolates with decreased ciprofloxacin susceptibility. Typhoid and paratyphoid fevers represent epidemiologically important diseases that may lead to potentially life-threatening complications. Major issue in the management of enteric fever represents the non-susceptibility of Salmonella strains to fluoroquinolones and other antimicrobials. PMID:25394534

  17. Identification of bacterial isolates in neonatal sepsis and their antimicrobial susceptibility.

    PubMed

    Haque, S M; Jahan, N; Mannan, M A; Hasan, M; Begum, M; Rob, S; Akhter, M; Yasmin, S; Hasnat, S K

    2014-10-01

    A cross-sectional descriptive study was conducted in the Neonatal Intensive Care Unit (NICU) of Ad-din Medical College Hospital during the period of January to December 2011 to determine the pattern of bacterial agents causing neonatal sepsis and their susceptibility pattern to various antimicrobial agents. Blood cultures were performed on admitted newborn babies (0-28 days) to rule out sepsis. Antimicrobial susceptibility testing was done for all blood culture isolates according to the criteria of the National Committee for Clinical Laboratory Standards by disk diffusion method. Out of 1000 screened blood cultures, 87(8.7%) reported as positive and the gram positive and gram negative bacteria accounted for 21(24.1%) and 66(75.9%) respectively. The most common gram positive organisms were Coagulase Negative Staphylococcus Aureus (CONS) (18.4%) and Staphylococcus Aureus (4.6%) and gram negative organisms were Acinetobacter (34.4%), Pseudomonas (21.8%) and Klebsiella spp. (6.9%). The susceptibilities were remarkably low to Ampicillin (20%) and Cefotaxim (29.6%) for both gram positive & gram negative isolates. Gram positive group had susceptibilities of 71.1% to Gentamicin, 85.7% to Imipenem & 100% to Amikacin & Vancomycin. Gram negative isolates showed higher sensitivities to Colistin (96.9%), Piperacillin-Tazobactum (78.7%), Imipenem (74.2%), Levofloxacillin (71.2%), respectively. Gram-negative bacteria showed high level of resistance to commonly used antibiotics (Ampicillin, Ceftazidim and Cefotaxim). Gentamicin, Amikacin, Imipenem and Levofloxacin were the most effective drugs compared to others. Routine bacterial surveillance and their sensitivity patterns must be an essential component of neonatal care. PMID:25481589

  18. Susceptibility testing of anaerobic bacteria: myth, magic, or method?

    PubMed Central

    Wexler, H M

    1991-01-01

    The demand for susceptibility testing of anaerobes has increased, yet consensus as to procedure and interpretation in this area has not been achieved. While routine testing of anaerobic isolates is not needed, certain isolates in specific clinical settings should be tested. Also, laboratories may monitor their local antibiograms by doing periodic surveillance batch testing. The National Committee for Clinical Laboratory Standards has published a protocol of methods approved for susceptibility testing of anaerobic bacteria. Both agar and broth microdilution are included; however, the broth disk elution method is no longer approved by the National Committee for Clinical Laboratory Standards because of method-related interpretive errors. A number of newer methods are undergoing evaluation and seem promising. Clinicians and microbiologists reviewing susceptibility reports should be aware of sources of variability in the test results. Variables in susceptibility testing of anaerobes include the media and methods used, organisms chosen for testing, breakpoints chosen for interpretation, antibiotic, and determination of endpoint. Clustering of MICs around the breakpoint may lead to significant variability in test results. Adherence of testing laboratories to approved methods and careful descriptions of the method and the breakpoints used for interpretation would facilitate interlaboratory comparisons and allow problems of emerging resistance to be noted. A variety of resistance mechanisms occurs in anaerobic bacteria, including the production of beta-lactamase and other drug-inactivating enzymes, alteration of target proteins, and inability of the drug to penetrate the bacterial wall. Antimicrobial resistance patterns in the United States and abroad are described. PMID:1747863

  19. In vitro susceptibility to antimicrobial drugs of 62 Salmonella strains isolated from horses in The Netherlands.

    PubMed

    van Duijkeren, E; van Klingeren, B; Vulto, A G; Sloet van Oldruitenborgh-Oosterbaan, M M; Breukink, H J; van Miert, A S

    1995-06-01

    The in vitro activity of 17 antimicrobial drugs against strains of Salmonella typhimurium (n = 52), Salmonella thompson (n = 2), Salmonella heidelberg (n = 3), Salmonella hadar (n = 2), Salmonella enteritidis (n = 1), Salmonella infantis (n = 1) and Salmonella derby (n = 1) was tested using the agar dilution method. The strains were isolated from horses admitted to the Large Animal Clinics of Utrecht University. The majority of strains were susceptible to gentamicin, amikacin, kanamycin, enrofloxacin, ciprofloxacin, flumequine, colistine, furazolidone and ceftiofur. However, all strains of Salmonella typhimurium phage type 200 (n = 14), were multiresistant i.e. were resistant to ampicillin amoxycillin, amoxycillin in combination with clavulanic acid, chloramphenicol, nitrofurantoin, trimethoprim, aditoprim and baquiloprim. Two of these strains were also resistant to gentamicin. Based on the susceptibility data found in the present study in combination with pharmacokinetic data available in the literature a rationale for antimicrobial therapy in equine salmonellosis is given. As first choice, gentamicin at a dosage of 3 mg/kg combined with ampicillin at a dosage of 20 mg/kg given with a 8-12 hour dosing interval by intravenous route is advised. As an alternative, the intravenous administration of trimethoprim/sulfonamide combinations given twice daily at a combined dose of 30 mg/kg is suggested. PMID:7653025

  20. In vitro susceptibility of Bordetella parapertussis to various antimicrobial agents.

    PubMed Central

    Watanabe, M; Haraguchi, Y

    1989-01-01

    The in vitro activity of 18 antimicrobial agents against 32 strains of Bordetella parapertussis isolated from whooping cough patients was studied. The most active antimicrobial agents were piperacillin and minocycline, followed (in descending order of activity) by moxalactam, erythromycin, cefoperazone, tetracycline, ampicillin, cefotaxime, chloramphenicol, josamycin, sulfamethoxazole, and nalidixic acid. Isolates were resistant to benzylpenicillin, cephalothin, cefatrizine, cefaclor, streptomycin, and cephalexin. PMID:2764546

  1. Prevalence and antimicrobial susceptibility of Campylobacter spp. in live and dressed chicken in Jordan.

    PubMed

    Osaili, Tareq M; Alaboudi, Akram R; Al-Akhras, Rani R

    2012-01-01

    A total of 140 broiler flocks presented for slaughtering at Amman slaughterhouse were tested for Campylobacter spp. via collection of cloacal swabs from live birds, feathered skin samples at prescalding, and skin samples at postscalding (62°C or 57°C scalding temperature), postevisceration, and postchilling. The results indicated that 40% of the flocks tested by cloacal swabs, 34% at prescalding, 32% at post 57°C scalding, and 32% postevisceration were harboring Campylobacter jejuni. None of the skin samples collected from dressed birds at postscalding (62°C) or postwashing-chilling steps (regardless of scalding temperature) revealed the presence of C. jejuni. Thirty eight isolates were tested for susceptibility to ten antimicrobials by using the microbroth dilution method. Almost 50% of the isolates were multidrug resistant to 9 or 10 out of the ten tested antimicrobials. The other half of tested isolates were sensitive to erythromycin, tetracycline, doxycyclin, chlortetracycline, ciprofloxacin, enorfloxacin, gentamycin, tilmicosin, amoxicillin, and trimethoprim. PMID:21988398

  2. Susceptibility testing with the sensititer breakpoint broth microdilution system.

    PubMed

    Doern, G V; Dascal, A; Keville, M

    1985-05-01

    The antimicrobial susceptibility profiles of a total of 318 aerobic and facultatively anaerobic bacteria (255 gram-negative bacilli and 63 gram-positive cocci) were determined, using a new commercially available breakpoint broth microdilution procedure (Sensititer Breakpoint System (SBS), Gibco Diagnostics, Inc., Madison, WI) that categorizes test results in the form of susceptibility categories: susceptible, intermediate, and resistant. Results obtained with the SBS were compared with those achieved with a standardized disk diffusion procedure. Among a total of 4,414 organism-antimicrobic comparisons, concordance between the results of the SBS and the disk diffusion procedure was observed in 3,888 cases (88.1%). Four hundred twenty-three (9.6%) minor discrepancies, 45 (1.0%) major discrepancies, and 58 (1.3%) very major discrepancies were noted. Arbitration of major and very major discrepancies with a full-range minimum inhibitory concentration (MIC) procedure confirmed the results of the SBS in 53.4% of cases. A single organism-antimicrobial combination, the nonenterococcal streptococci tested against the aminoglycosides, yielded a significant number of very major errors which were arbitrated in favor of the disk diffusion result. These errors were probably due to poor growth of the test organism in the broth medium used for performing the SBS test (i.e., cation-supplemented Mueller-Hinton broth). With this exception, the SBS was found to be at least as accurate as the standardized disk diffusion procedure. PMID:3922668

  3. Comparison of Prevalence and Antimicrobial Susceptibilities of Campylobacter spp. Isolates from Organic and Conventional Dairy Herds in Wisconsin

    PubMed Central

    Sato, K.; Bartlett, P. C.; Kaneene, J. B.; Downes, F. P.

    2004-01-01

    The prevalence and antimicrobial susceptibilities of Campylobacter spp. isolates from bovine feces were compared between organic and conventional dairy herds. Thirty organic dairy herds, where antimicrobials are rarely used for calves and never used for cows, were compared with 30 neighboring conventional dairy farms, where antimicrobials were routinely used for animals for all ages. Fecal specimens from 10 cows and 10 calves on 120 farm visits yielded 332 Campylobacter isolates. The prevalence of Campylobacter spp. in organic and conventional farms was 26.7 and 29.1%, and the prevalence was not statistically different between the two types of farms. Campylobacter prevalence was significantly higher in March than in September, higher in calves than in cows, and higher in smaller farms than in large farms. The rates of retained placenta, pneumonia, mastitis, and abortion were associated with the proportion of Campylobacter isolation from fecal samples. The gradient disk diffusion MIC method (Etest) was used for testing susceptibility to four antimicrobial agents: ciprofloxacin, gentamicin, erythromycin, and tetracycline. Two isolates were resistant to ciprofloxacin, and none of isolates was resistant to gentamicin or erythromycin. Resistance to tetracycline was 45% (148 of 332 isolates). Tetracycline resistance was found more frequently in calves than in cows (P = 0.042), but no difference was observed between organic and conventional farms. When we used Campylobacter spp. as indicator bacteria, we saw no evidence that restriction of antimicrobial use on dairy farms was associated with prevalence of resistance to ciprofloxacin, gentamicin, erythromycin, and tetracycline. PMID:15006764

  4. Identification, molecular characterisation and antimicrobial susceptibility of genomovars of the Burkholderia cepacia complex in Spain.

    PubMed

    Medina-Pascual, M J; Valdezate, S; Villalón, P; Garrido, N; Rubio, V; Saéz-Nieto, J A

    2012-12-01

    Burkholderia spp. strains collected in Spain over a 13-year period from patients with cystic fibrosis (CF) (n = 148), non-CF patients (n = 103) and from environmental sources (n = 64) were characterised. One hundred and forty-one of the examined strains were involved in seven suspected nosocomial disease outbreaks. Strains were identified by their 16s rRNA and recA genes. Their genetic relatedness, the possession of cable pili and the B. cepacia epidemic strain marker (BCESM), and their susceptibility to antimicrobial agents were studied using pulsed-field gel electrophoresis (PFGE), cblA and esmR genes analysis, and by the E-test, respectively. The genomovar distribution for the 315 strains was as follows: B. stabilis 29.5 %, B. cepacia 14.9 %, B. multivorans 11.1 %, B. cenocepacia IIIA 9.5 %, B. vietnamiensis 3.8 %, B. cenocepacia IIIB 3.5 %, and B. ambifaria and B. pyrrocinia 0.3 % each. The genetic diversity of the B. cepacia complex (Bcc) was ample, with 57 different SpeI types, showing a genetic similarity of 36.4-96.6 %. No strain carried cblA, whereas 25 B. cenocepacia genotypes harboured BCESM (23 from patients with CF). Antimicrobial resistance rates to tobramycin (TOB; 86 %) and imipenem (IPM; 67 %) were high. The strains from patients with CF showed significantly greater resistance to piperacillin (PIP), levofloxacin (LVX) and co-trimoxazole (SXT) than those isolated from non-CF patients (p < 0.05). In conclusion, B. cenocepacia was the most prevalent genomovar found in patients with CF (19.1 %), whereas B. cepacia was the most common among non-CF patients (20.7 %). B. stabilis (47.6 %) was the most common environmental genomovar. Susceptibility to antimicrobial agents depended on genomovar status and strain origin. PMID:22855365

  5. Antimicrobial susceptibility of Pseudomonas aeruginosa isolates from dogs with otitis externa.

    PubMed

    Mekić, S; Matanović, K; Šeol, B

    2011-07-30

    Pseudomonas aeruginosa is a common cause of otitis externa in dogs, and treatment of these infections is becoming problematic because of the increasing number of multiresistant strains. The aim of the present study was to compare the in vitro activities of cefepime, ceftazidime, enrofloxacin, ciprofloxacin, gentamicin and ticarcillin/clavulanic acid against 104 strains of P aeruginosa isolated from dogs with otitis externa. Antimicrobial susceptibility and minimum inhibitory concentrations, in µg/ml, were evaluated by the E test (bioMérieux). The most active compound was ceftazidime, with 100 per cent efficiency. The majority of tested strains were susceptible to ticarcillin/clavulanic acid (89.4 per cent), followed by ciprofloxacin (88.5 per cent) and cefepime (60.6 per cent). The highest resistance was observed to enrofloxacin (51.9 per cent) and gentamicin (43.3 per cent). Large numbers of strains were intermediately susceptible to antibiotics registered for use in veterinary medicine in Croatia--enrofloxacin (47.1 per cent) and gentamicin (41.3 per cent). PMID:21742683

  6. Antimicrobial susceptibility of clinical isolates from earthquake victims in Wenchuan.

    PubMed

    Kang, M; Xie, Y; Mintao, C; Chen, Z; Chen, H; Fan, H; Chen, W; Guo, X

    2009-01-01

    On 12 May 2008, an earthquake measuring 8.0 on the Richter scale struck Wenchuan County, Sichuan, China. Between 12 May and 11 June, 1823 victims were hospitalized in West China Hospital. These patients were severely injured, and most of their wounds were contaminated. Here, the results of bacteriological identification and antibiotic susceptibility testing of 725 non-duplicate isolates from earthquake victims are presented. Gram-negative bacilli were most frequently isolated (71.3%). Only 18.9% of isolates were Gram-positive bacteria; Candida spp. accounted for 9.7%, and Gram-negative cocci for 0.1%. After anaerobic culture, four Clostridium sordellii strains and one Clostridium bifermentans strain were isolated from deep wounds. Specimen culture from earthquake victims revealed a spectrum of pathogens and antibiotic susceptibilities that was different from that usually encountered in West China Hospital, especially concerning methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase producers, and multidrug-resistant (MDR) non-fermenting Gram-negative bacilli. The pathophysiology of the injuries in earthquake victims was different from that in the patients who were not earthquake victims. A combination of environmental bacteria with a high proportion of Gram-negative bacteria was often observed in the earthquake victims. Approximately 26% of all earthquake victims were shown to be carriers of MDR microorganisms. Therefore, appropriate microbiological assessment upon admission, and identification of patients to be put in quarantine, is of paramount importance. PMID:19220339

  7. Mycoplasma bovis: Mechanisms of Resistance and Trends in Antimicrobial Susceptibility.

    PubMed

    Lysnyansky, Inna; Ayling, Roger D

    2016-01-01

    Mycoplasma bovis is a cell-wall-less bacterium and belongs to the class Mollicutes. It is the most important etiological agent of bovine mycoplasmoses in North America and Europe, causing respiratory disease, mastitis, otitis media, arthritis, and reproductive disease. Clinical disease associated with M. bovis is often chronic, debilitating, and poorly responsive to antimicrobial therapy, resulting in significant economic loss, the full extent of which is difficult to estimate. Until M. bovis vaccines are universally available, sanitary control measures and antimicrobial treatment are the only approaches that can be used in attempts to control M. bovis infections. However, in vitro studies show that many of the current M. bovis isolates circulating in Europe have high minimum inhibitory concentrations (MIC) for many of the commercially available antimicrobials. In this review we summarize the current MIC trends indicating the development of antimicrobial resistance in M. bovis as well as the known molecular mechanisms by which resistance is acquired. PMID:27199926

  8. Mycoplasma bovis: Mechanisms of Resistance and Trends in Antimicrobial Susceptibility

    PubMed Central

    Lysnyansky, Inna; Ayling, Roger D.

    2016-01-01

    Mycoplasma bovis is a cell-wall-less bacterium and belongs to the class Mollicutes. It is the most important etiological agent of bovine mycoplasmoses in North America and Europe, causing respiratory disease, mastitis, otitis media, arthritis, and reproductive disease. Clinical disease associated with M. bovis is often chronic, debilitating, and poorly responsive to antimicrobial therapy, resulting in significant economic loss, the full extent of which is difficult to estimate. Until M. bovis vaccines are universally available, sanitary control measures and antimicrobial treatment are the only approaches that can be used in attempts to control M. bovis infections. However, in vitro studies show that many of the current M. bovis isolates circulating in Europe have high minimum inhibitory concentrations (MIC) for many of the commercially available antimicrobials. In this review we summarize the current MIC trends indicating the development of antimicrobial resistance in M. bovis as well as the known molecular mechanisms by which resistance is acquired. PMID:27199926

  9. Antimicrobial susceptibility profiles of Salmonella enterica serotypes recovered from pens of commercial feedlot cattle using different types of composite samples.

    PubMed

    Alam, Mohammad Jahangir; Renter, David; Taylor, Ethel; Mina, Diana; Moxley, Rodney; Smith, David

    2009-04-01

    Salmonella enterica in cattle production systems may be associated with important human and animal disease issues. However, tremendous diversity exists among Salmonella recovered, and more information is needed about strains of greatest potential health concern, particularly those that are multidrug resistant (MDR). By characterizing Salmonella isolates from commercial feedlot pens, this study aimed to evaluate the strain diversity and prevalence of MDR Salmonella from different types of composite pen samples. Antimicrobial susceptibility profiles, serotype, and presence or absence of the integron-encoded intI1 gene were determined for 530 Salmonella isolates recovered using composite rope (n = 335), feces (n = 59), and water (n = 136) samples from 21 pens in 3 feedlots. The study investigated only pens with available isolates from multiple sample types. Most isolates (83.0%) of the 19 Salmonella serotypes identified were susceptible or intermediately susceptible to all the antimicrobials evaluated. Resistance to sulfisoxazole (14.9%), streptomycin (3.8%), and tetracycline (3.6%) were the most common. None of the isolates tested positive for a class 1 integron, and only 2.5% were resistant to multiple antimicrobials. All the MDR isolates, namely, serotypes Uganda (n = 9), Typhimurium (n = 2), and Give (n = 2), were resistant to at least five antimicrobials. Most MDR isolates (n = 11) were from two pens during 1 week within one feedlot. Overall, many Salmonella isolates collected within a pen were similar in terms of serotype and antimicrobial susceptibility regardless of sample type. However, MDR Salmonella and rare serotypes were not recovered frequently enough to suggest a general strategy for appropriate composite sampling of feedlot cattle populations for Salmonella detection and monitoring. PMID:19219500

  10. Phenotypic Description and Antimicrobial Susceptibilities of Aerococcus sanguinicola Isolates from Human Clinical Samples

    PubMed Central

    Facklam, Richard; Lovgren, Marguerite; Shewmaker, Patricia Lynn; Tyrrell, Gregory

    2003-01-01

    This report describes the clinical sources and phenotypic characterization of 16 isolates of Aerococcus sanguinicola. Sixteen conventional tests were used to describe and differentiate the 16 isolates of A. sanguinicola from 30 strains of Aerococcus viridans, 27 strains of Aerococcus urinae, and a single strain each of Aerococcus christensenii and Aerococcus urinaehominis. The phenotypic characterizations of the type strains for each species and 14 A. sanguinicola isolates were also compared in the two reference laboratories. A. sanguinicola are catalase-negative, vancomycin-susceptible, gram-positive cocci arranged in clusters and tetrads, as are all Aerococcus species except A. christensenii (which is arranged in short chains). All 16 isolates of A. sanguinicola were leucine aminopeptidase and pyrrolidonylarylamidase positive, which is unique to this species among the aerococci. All A. sanguinicola isolates grew in broth containing 6.5% NaCl, hydrolyzed hippurate, and were variable in the bile-esculin test. None of the isolates deaminated arginine or were Voges-Proskauer positive. The type strain of A. sanguinicola was isolated from a blood culture of a patient living in Denmark. Seven additional isolates were from patients living in Canada, all with urinary tract infections (six were female). Eight isolates were from patients living in five different states in the United States; five were from patients with urinary tract infections, and three were from blood cultures of one patient each with pneumonia, suspected endocarditis, and unknown clinical conditions. The antimicrobial susceptibility patterns were unremarkable; all isolates tested were susceptible to penicillin, amoxicillin, cefotaxime, cefuroxime, erythromycin, chloramphenicol, vancomycin, quinupristin-dalfopristin (Synercid), rifampin, linezolid, and tetracycline. Six of the 15 cultures were resistant to ciprofloxacin and levofloxacin, but all 15 strains were susceptible to sparfloxacin. High

  11. Phenotypic description and antimicrobial susceptibilities of Aerococcus sanguinicola isolates from human clinical samples.

    PubMed

    Facklam, Richard; Lovgren, Marguerite; Shewmaker, Patricia Lynn; Tyrrell, Gregory

    2003-06-01

    This report describes the clinical sources and phenotypic characterization of 16 isolates of Aerococcus sanguinicola. Sixteen conventional tests were used to describe and differentiate the 16 isolates of A. sanguinicola from 30 strains of Aerococcus viridans, 27 strains of Aerococcus urinae, and a single strain each of Aerococcus christensenii and Aerococcus urinaehominis. The phenotypic characterizations of the type strains for each species and 14 A. sanguinicola isolates were also compared in the two reference laboratories. A. sanguinicola are catalase-negative, vancomycin-susceptible, gram-positive cocci arranged in clusters and tetrads, as are all Aerococcus species except A. christensenii (which is arranged in short chains). All 16 isolates of A. sanguinicola were leucine aminopeptidase and pyrrolidonylarylamidase positive, which is unique to this species among the aerococci. All A. sanguinicola isolates grew in broth containing 6.5% NaCl, hydrolyzed hippurate, and were variable in the bile-esculin test. None of the isolates deaminated arginine or were Voges-Proskauer positive. The type strain of A. sanguinicola was isolated from a blood culture of a patient living in Denmark. Seven additional isolates were from patients living in Canada, all with urinary tract infections (six were female). Eight isolates were from patients living in five different states in the United States; five were from patients with urinary tract infections, and three were from blood cultures of one patient each with pneumonia, suspected endocarditis, and unknown clinical conditions. The antimicrobial susceptibility patterns were unremarkable; all isolates tested were susceptible to penicillin, amoxicillin, cefotaxime, cefuroxime, erythromycin, chloramphenicol, vancomycin, quinupristin-dalfopristin (Synercid), rifampin, linezolid, and tetracycline. Six of the 15 cultures were resistant to ciprofloxacin and levofloxacin, but all 15 strains were susceptible to sparfloxacin. High

  12. Direct comparison of the BD phoenix system with the MicroScan WalkAway system for identification and antimicrobial susceptibility testing of Enterobacteriaceae and nonfermentative gram-negative organisms.

    PubMed

    Snyder, J W; Munier, G K; Johnson, C L

    2008-07-01

    The Phoenix automated microbiology system (BD Diagnostics, Sparks, MD) is designed for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically significant human bacterial pathogens. We evaluated the performance of the Phoenix instrument in comparison with that of the MicroScan WalkAway system (Dade Behring, West Sacramento, CA) in the ID and AST of gram-negative clinical strains and challenge isolates of Enterobacteriaceae (n = 150) and nonfermentative gram-negative bacilli (NFGNB; 45 clinical isolates and 8 challenge isolates). ID discrepancies were resolved with the API 20E and API 20NE conventional biochemical ID systems (bioMerieux, Durham, NC). The standard disk diffusion method was used to resolve discordant AST results. The overall percentages of agreement between the Phoenix ID results and the MicroScan results at the genus and species levels for clinical isolates of Enterobacteriaceae were 98.7 and 97.7%, respectively; following resolution with conventional biochemical testing, the accuracy of the Phoenix system was determined to be 100%. For NFGNB, the levels of agreement were 100 and 97.7%, respectively. Both systems incorrectly identified the majority of the uncommon nonfermentative nonpseudomonal challenge isolates recovered from cystic fibrosis patients; these isolates are not included in the databases of the respective systems. For AST of Enterobacteriaceae, the rate of complete agreement between the Phoenix results and the MicroScan results was 97%; the rates of very major, major, and minor errors were 0.3, 0.2, and 2.7%, respectively. For NFGNB, the rate of complete agreement between the Phoenix results and the MicroScan results was 89.1%; the rates of very major, major, and minor errors were 0, 0.5, and 7.7%, respectively. Following the confirmatory testing of nine clinical isolates initially screened by the MicroScan system as possible extended-spectrum-beta-lactamase (ESBL)-producing organisms (seven Klebsiella

  13. Differential Antimicrobial Susceptibilities of Granulicatella adiacens and Abiotrophia defectiva.

    PubMed

    Mushtaq, Ammara; Greenwood-Quaintance, Kerryl E; Cole, Nicolynn C; Kohner, Peggy C; Ihde, Sherry M; Strand, Gregory J; Harper, Lance W; Virk, Abinash; Patel, Robin

    2016-08-01

    MICs of 25 Abiotrophia defectiva and 109 Granulicatella adiacens isolates were determined by broth microdilution. Using CLSI breakpoints, the susceptibilities of A. defectiva and G. adiacens isolates were, respectively, 24% and 34% to penicillin, 92% and 22% to ceftriaxone, 48% and 3% to cefepime, 72% and 87% to meropenem, 92% and 10% to cefotaxime, 100% and 97% to levofloxacin, 92% and 80% to clindamycin, and 24% and 50% to erythromycin. All isolates were susceptible to vancomycin. In the penicillin-susceptible subgroup, all A. defectiva isolates were susceptible to ceftriaxone; however, 62% of G. adiacens isolates were ceftriaxone nonsusceptible. PMID:27216060

  14. Bacterial nanoscale cultures for phenotypic multiplexed antibiotic susceptibility testing.

    PubMed

    Weibull, Emilie; Antypas, Haris; Kjäll, Peter; Brauner, Annelie; Andersson-Svahn, Helene; Richter-Dahlfors, Agneta

    2014-09-01

    An optimal antimicrobial drug regimen is the key to successful clinical outcomes of bacterial infections. To direct the choice of antibiotic, access to fast and precise antibiotic susceptibility profiling of the infecting bacteria is critical. We have developed a high-throughput nanowell antibiotic susceptibility testing (AST) device for direct, multiplexed analysis. By processing in real time the optical recordings of nanoscale cultures of reference and clinical uropathogenic Escherichia coli strains with a mathematical algorithm, the time point when growth shifts from lag phase to early logarithmic phase (Tlag) was identified for each of the several hundreds of cultures tested. Based on Tlag, the MIC could be defined within 4 h. Heatmap presentation of data from this high-throughput analysis allowed multiple resistance patterns to be differentiated at a glance. With a possibility to enhance multiplexing capacity, this device serves as a high-throughput diagnostic tool that rapidly aids clinicians in prescribing the optimal antibiotic therapy. PMID:24989602

  15. Antimicrobial susceptibility of environmental bovine mastitis pathogens in west central Iran.

    PubMed

    Ebrahimi, Azizollah; Kheirabadi, K H Pirali; Nikookhah, Farzaneh

    2007-09-01

    The purpose of this study was to describe antimicrobial susceptibility of environmental mastitis pathogens isolated from dairy herds of Chahar Mahal province in west central Iran. Out of the 620 milk samples collected from the four districts, 180 were CMT (California mastitis test) positive that cultured and yield, 7 (3.88%) coagulase negative Staphylococci (CNS), 15 (8.33%) Streptococci other than agalactiae and 17 (9.44%) E. coli. CNS resistance to penicillin was 14.28% but for streptomycin, Oxytetracycline and Colistin, were 28.57%. Non agalactiae Streptococci resistance to Oxytetracycline and Kanamycin were 20 and 13.33%, respectively. E. coli resistance to penicillin, oxytetracycline, streptomycin, erythromycin and Colistin were 88.23, 82.35, 76.47, 76.47 and 52.94%, respectively. PMID:19090221

  16. Susceptibility to antimicrobial agents and plasmid carrying in Aeromonas hydrophila isolated from two estuarine systems.

    PubMed

    Montoya, R; Dominguez, M; Gonzalez, C; Mondaca, M A; Zemelman, R

    1992-01-01

    Susceptibility to various antimicrobial agents and the presence of plasmids was investigated in eleven strains of Aeromonas hydrophila isolated from samples of sea water and these strains isolated from Aulacomya ater. Transference of resistance to Escherichia coli was attempted by conjugation and transformation experiments. The strains showed multiple resistance toward beta-lactam antibiotics and susceptibility to other antimicrobial agents. Five strains harboured plasmids with molecular weights below 5.7 MD. It was not possible to relate the resistance of the strains with the presence of their plasmids. PMID:1593967

  17. Antimicrobial susceptibility of Gram-negative organisms isolated from patients hospitalised with pneumonia in US and European hospitals: results from the SENTRY Antimicrobial Surveillance Program, 2009-2012.

    PubMed

    Sader, Helio S; Farrell, David J; Flamm, Robert K; Jones, Ronald N

    2014-04-01

    Here we evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from patients hospitalised with pneumonia in medical centres in the USA (n=28) and Europe and the Mediterranean region (EMR) (n=25) in 2009-2012. Susceptibility testing was performed by reference broth microdilution methods. Overall, 12851 isolates were collected (6873/5978 in USA/EMR). The same top 11 organisms were observed in both geographic regions, but in different rank orders, and Gram-negative organisms represented 61.5/76.1% of strains in USA/EMR. Pseudomonas aeruginosa was the most frequently isolated Gram-negative organism in both regions (20.9/20.9% of cases in USA/EMR) and showed reduced susceptibility to most antimicrobials tested, including ceftazidime (79.6/68.7% susceptibility in USA/EMR), meropenem (76.3/65.8%) and piperacillin/tazobactam (72.9/63.9%). Klebsiella spp. was isolated from 9.7/11.6% of cases and showed extended-spectrum β-lactamase (ESBL) phenotype rates of 19.5/35.1% in USA/EMR. Meropenem and amikacin were active against 62.3/78.7% and 60.8/85.2% of ESBL phenotype Klebsiella spp. from USA/EMR, respectively. Enterobacter spp. ranked fourth in the USA (5.9%) and sixth in EMR (5.5%), whereas Escherichia coli ranked fifth in the USA (5.5%) and third in EMR (11.8%). Acinetobacter spp. and Stenotrophomonas maltophilia combined were isolated from 8.0/10.7% of cases in USA/EMR. A significant increase in P. aeruginosa susceptibility to meropenem and a significant decrease in gentamicin susceptibility among Klebsiella spp. were noted in EMR. These results confirm that very few agents remain broadly active against the most frequently isolated Gram-negative organisms from patients with pneumonia in US and EMR medical centres. PMID:24630306

  18. Serotype Distribution, Antimicrobial Susceptibility, and Molecular Epidemiology of Streptococcus pneumoniae Isolated from Children in Shanghai, China

    PubMed Central

    Pan, Fen; Han, Lizhong; Huang, Weichun; Tang, Jin; Xiao, Shuzhen; Wang, Chun; Qin, Huihong; Zhang, Hong

    2015-01-01

    Objective Streptococcus pneumoniae is a common pathogenic cause of pediatric infections. This study investigated the serotype distribution, antimicrobial susceptibility, and molecular epidemiology of pneumococci before the introduction of conjugate vaccines in Shanghai, China. Methods A total of 284 clinical pneumococcal isolates (270, 5, 4,3, and 2 of which were isolated from sputum, bronchoalveolar lavage fluid, blood, cerebral spinal fluid, and ear secretions, respectively) from children less than 14 years of age who had not been vaccinated with a conjugate vaccine, were collected between January and December in 2013. All isolates were serotyped by multiplex polymerase chain reaction or quellung reactions and antimicrobial susceptibility testing was performed using the broth microdilution method. The molecular epidemiology of S.pneumoniae was analyzed by multilocus sequence typing (MLST). Results Among the 284 pneumococcal isolates, 19F (33.5%), 19A (14.1%), 23F (12.0%), and 6A (8.8%) were the most common serotypes and the coverage rates of the 7-, 10-, and 13-valent pneumococcal conjugate vaccines (PCV7, PCV10, and PCV13) were 58.6%, 59.4% and 85.1%, respectively. Antimicrobial susceptibility showed that the prevalence rates of S.pneumoniae resistance to penicillin were 11.3% (32/284). Approximately 88.0% (250/284) of the isolates exhibited multi-drug resistance. MLST analysis revealed a high level of diversity, with 65 sequence types (STs) among 267 isolates. Specifically, the four predominant STs were ST271 (24.3%, 65/267), ST320 (11.2%, 30/267), ST81 (9.7%, 26/267), and ST3173 (5.2%, 14/267), which were mainly associated with serotypes 19F, 19A, 23F, and 6A, respectively. Conclusions The prevalent serotypes among clinical isolates from children were 19F, 19A, 23F, and 6A and these isolates showed high resistance rates to β-lactams and macrolides. The Taiwan19F-14 clone played a predominant role in the dissemination of pneumococcal isolates in Shanghai

  19. In Vitro Susceptibility of Equine-Obtained Isolates of Corynebacterium pseudotuberculosis to Gallium Maltolate and 20 Other Antimicrobial Agents

    PubMed Central

    Batista, M.; Lawhon, S. D.; Zhang, S.; Kuskie, K. R.; Swinford, A. K.; Bernstein, L. R.; Cohen, N. D.

    2014-01-01

    This study's objective was to determine the in vitro antimicrobial activities of gallium maltolate (GaM) and 20 other antimicrobial agents against clinical equine isolates of Corynebacterium pseudotuberculosis. The growth of cultured isolates was not inhibited by any concentration of GaM. MIC data revealed susceptibility to commonly used antimicrobials. PMID:24829243

  20. In vitro antimicrobial susceptibilities of strains of Yersinia pestis.

    PubMed Central

    Smith, M D; Vinh, D X; Nguyen, T T; Wain, J; Thung, D; White, N J

    1995-01-01

    The in vitro activities of 14 antimicrobial agents were determined for 78 strains of Yersinia pestis. The most active antibiotics were ceftriaxone and ciprofloxacin, followed by ofloxacin and ampicillin. The agents traditionally used for the treatment of plague (streptomycin, tetracycline, and chloramphenicol) were considerably less active. Azithromycin showed poor activity against all strains. PMID:8540736

  1. Streptococcus pneumoniae non-susceptibility and outpatient antimicrobial prescribing rates at the Alaska Native Medical Center

    PubMed Central

    Stevens, Ryan W.; Wenger, Jay; Bulkow, Lisa; Bruce, Michael G.

    2013-01-01

    Background American Indian/Alaska Native (AI/AN) people suffer substantially higher rates of invasive pneumococcal disease (IPD) than the general US population. We evaluated antimicrobial prescribing data and their association with non-susceptibility in Streptococcus pneumoniae causing IPD in AI/AN people between 1992 and 2009. Methods Antimicrobial use data were gathered from the electronic patient management system and included all prescriptions dispensed to Alaska Native patients aged 5 years and older from outpatient pharmacies at the Alaska Native Medical Center (ANMC). Antimicrobial susceptibility data were gathered from pneumococcal isolates causing IPD among Anchorage Service Unit AI/AN residents aged 5 years and older. Data were restricted to serotypes not contained in the pneumococcal vaccine (PCV7). Results Over the study period, overall antimicrobial prescribing increased 59% (285/1,000 persons/year in 1992 to 454/1,000 persons per year in 2009, p<0.001). Trimethoprim/sulfamethoxazole prescribing increased (43/1,000 persons/year in 1992 to 108/1,000 persons/year in 2009, p<0.001) and non-susceptibility to trimethoprim/sulfamethoxazole in AI/AN patients ≥5 years of age increased in non-PCV7 serotypes (0–12%, p<0.05). Similarly, prescribing rates increased for macrolide antibiotics (46/1,000 persons/year in 1992 to 84/1,000 persons/year in 2009, p<0.05). We observed no statistically significant change over time in erythromycin non-susceptibility among non-PCV7 serotypes in AI/AN patients aged 5 years or greater (0–7%, p=0.087). Conclusion Antimicrobial prescribing patterns of some antibiotics in the AI/AN population corresponded to increased antimicrobial resistance in clinical isolates. This study highlights the on-going threat of antimicrobial resistance, the critical importance of judicious prescribing of antibiotics and the potential utility of prescribing data for addressing this issue. PMID:24358456

  2. Comparison of Antimicrobial Susceptibility of Campylobacter Strains Isolated from Food Samples and Patients with Diarrhea

    PubMed Central

    Bakhshi, Bita; Naseri, Amin; Alebouyeh, Masoud

    2016-01-01

    Background: Campylobacter infections may lead to serious conditions, including septicemia or other invasive forms of the disease, which require rapid and accurate laboratory diagnosis and subsequently appropriate antimicrobial therapy. The aim of this study was to compare the species distribution and antimicrobial susceptibility pattern of Campylobacter spp. strains isolated from patients and food samples. Methods: Biochemical identification was performed on 15 clinical and 30 food isolates of Campylobacter recovered onto Brucella agar containing 5% sheep blood. PCR was carried out to confirm the identity of Campylobacter spp. using primers for cadF, hipO, and asp genes of Campylobacter. To determine antibiotic sensitivity of isolates, Kirby-Bauer assay was carried out using 16 different antibiotic discs. Results: PCR assay and biochemical tests confirmed all 45 isolates as Campylobacter: 20 (44.44%) as C. jujeni, 10 (22.22%) as C. coli, and 15 (33.34%) as other Campylobacter strains. The maximum resistance was observed to cefotaxime and imipenem (each 86.49%) and the maximum sensitivity to erythromycin (48.65%). Conclusion: C. jujeni is dominant among isolates from clinical and food samples. In addition, tetracycline remains the first-line therapeutic agent against Campylobacter infections in Iran. PMID:26783018

  3. In vitro effect of antibiotics on biofilm formation by Bacteroides fragilis group strains isolated from intestinal microbiota of dogs and their antimicrobial susceptibility.

    PubMed

    Silva, Janice Oliveira; Martins Reis, Ana Catarina; Quesada-Gómez, Carlos; Pinheiro, Adriana Queiroz; Freire, Rosemary Souza; Oriá, Reinaldo Barreto; de Carvalho, Cibele Barreto Mano

    2014-08-01

    The Bacteroides fragilis group strains colonize the intestinal tract of dogs as commensal bacteria. Nevertheless, they can be opportunistic pathogens responsible for significant morbidity and mortality rates in dogs, like in oral infections, abscesses and wound infections. The purpose of this study was to evaluate antimicrobial susceptibility in B. fragilis strains isolated from dogs intestinal microbiota and to evaluate the effect of subinhibitory concentrations of some antimicrobials on biofilm formation. A total of 30 B. fragilis group strains were tested for susceptibility to ten antimicrobial agents by broth microdilution method. Thirteen B. fragilis strains were tested for biofilm formation and the biofilm producer strains were chosen to evaluate the effect of subinhibitory concentrations of six antimicrobials on biofilm formation. The isolates were susceptible to amoxicillin-clavulanic acid, metronidazole, imipenem and chloramphenicol. Tetracycline and clindamycin were active against 50% and 33% of the strains, respectively. When biofilm-forming strains were grown in the presence of sub-MICs of imipenem and metronidazole, the inhibition of biofilm formation was observed. In contrast, enrofloxacin at ½ MIC caused a significant increase in biofilm formation in two of four strains examined. In conclusion, the B. fragilis group strains isolated were susceptible to most of the antimicrobials tested and the sub-MIC concentrations of imipenem, metronidazole and clindamycin were able to inhibit the biofilm formation. PMID:24799339

  4. The second nationwide surveillance of the antimicrobial susceptibility of Neisseria gonorrhoeae from male urethritis in Japan, 2012-2013.

    PubMed

    Hamasuna, Ryoichi; Yasuda, Mitsuru; Ishikawa, Kiyohito; Uehara, Shinya; Hayami, Hiroshi; Takahashi, Satoshi; Matsumoto, Tetsuro; Yamamoto, Shingo; Minamitani, Shinichi; Watanabe, Akira; Iwata, Satoshi; Kaku, Mitsuo; Kadota, Junichi; Sunakawa, Keisuke; Sato, Junko; Hanaki, Hideaki; Tsukamoto, Taiji; Kiyota, Hiroshi; Egawa, Shin; Tanaka, Kazushi; Arakawa, Soichi; Fujisawa, Masato; Kumon, Hiromi; Kobayashi, Kanao; Matsubara, Akio; Naito, Seiji; Kuroiwa, Kentaro; Hirayama, Hideo; Narita, Harunori; Hosobe, Takahide; Ito, Shin; Ito, Kenji; Kawai, Shuichi; Ito, Masayasu; Chokyu, Hirofumi; Matsumura, Masaru; Yoshioka, Masaru; Uno, Satoshi; Monden, Koichi; Takayama, Kazuo; Kaji, Shinichi; Kawahara, Motoshi; Sumii, Toru; Kadena, Hitoshi; Yamaguchi, Takamasa; Maeda, Shinichi; Nishi, Shohei; Nishimura, Hirofumi; Shirane, Takeshi; Yoh, Mutsumasa; Akiyama, Kikuo; Imai, Toshio; Kano, Motonori

    2015-05-01

    Worldwide, the most important concern in the treatment of sexually transmitted infections is the increase in antimicrobial resistant Neisseria gonorrhoeae strains including resistance to cephalosporins, penicillins, fluoroquinolones or macrolides. To investigate the trends of antimicrobial susceptibility among N. gonorrhoeae strains isolated from male patients with urethritis, a Japanese surveillance committee conducted the second nationwide surveillance study. Urethral discharge was collected from male patients with urethritis at 26 medical facilities from March 2012 to January 2013. Of the 151 specimens, 103 N. gonorrhoeae strains were tested for susceptibility to 20 antimicrobial agents. None of the strains was resistant to ceftriaxone, but the minimum inhibitory concentration (MIC) 90% of ceftriaxone increased to 0.125 μg/ml, and 11 (10.7%) strains were considered less susceptible with an MIC of 0.125 μg/ml. There were 11 strains resistant to cefixime, and the MICs of these strains were 0.5 μg/ml. The distributions of the MICs of fluoroquinolones, such as ciprofloxacin, levofloxacin and tosufloxacin, were bimodal. Sitafloxacin, a fluoroquinolone, showed strong activity against all strains, including strains resistant to other three fluoroquinolones, such as ciprofloxacin, levofloxacin and tosufloxacin. The azithromycin MICs in 2 strains were 1 μg/ml. PMID:25727286

  5. Drug susceptibility testing of nontuberculous mycobacteria.

    PubMed

    van Ingen, Jakko; Kuijper, Ed J

    2014-01-01

    Diseases caused by nontuberculous mycobacteria are emerging in many settings. With an increased number of patients needing treatment, the role of drug susceptibility testing is again in the spotlight. This articles covers the history and methodology of drug susceptibility tests for nontuberculous mycobacteria, but focuses on the correlations between in vitro drug susceptibility, pharmacokinetics and in vivo outcomes of treatment. Among slow-growing nontuberculous mycobacteria, clear correlations have been established for macrolides and amikacin (Mycobacterium avium complex) and for rifampicin (Mycobacterium kansasii). Among rapid-growing mycobacteria, correlations have been established in extrapulmonary disease for aminoglycosides, cefoxitin and co-trimoxazole. In pulmonary disease, correlations are less clear and outcomes of treatment are generally poor, especially for Mycobacterium abscessus. The clinical significance of inducible resistance to macrolides among rapid growers is an important topic. The true role of drug susceptibility testing for nontuberculous mycobacteria still needs to be addressed, preferably within clinical trials. PMID:25340838

  6. The identification, typing, and antimicrobial susceptibility of Pseudomonas aeruginosa isolated from mink with hemorrhagic pneumonia.

    PubMed

    Qi, Jing; Li, Lulu; Du, Yijun; Wang, Shourong; Wang, Jinwen; Luo, Yanbo; Che, Jie; Lu, Jinxing; Liu, Hui; Hu, Guangchun; Li, Jixia; Gong, Yanwen; Wang, Guisheng; Hu, Ming; Shiganyan; Liu, Yuqing

    2014-06-01

    The biological characteristics and molecular epidemiology of Pseudomonas aeruginosa associated with mink hemorrhagic pneumonia from Shandong province of eastern China were determined in this study. From 2010 to 2011, 30 mink P. aeruginosa isolates were identified from lung, fecal and feed samples of clinical cases and subjected to serotyping, antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE) using SpeI. The P. aeruginosa isolates belonged to four serotypes-21 of type G, four of type I, three of type M, one of type B, and one non-typable strain. The strains were divided into four large groups as determined by PFGE. Isolates from the group 2 were highly homologous and were obtained from the same region as an epidemic. All of the isolates were sensitive to piperacillin, piperacillin/tazobactam, ceftazidime, cefepime, imipenem, amikacin, gentamicin and tobramycin and resistant to ampicillin, cefuroxime and cefuroxime axetil. A high frequency of resistance was found to ampicillin/sulbactam, cefazolin, cefotetan, ceftriaxone, nitrofurantoin, and trimethoprim/sulfamethoxazole (96.7%). Resistance to ticarcillin/clavulanic acid, ciprofloxacin and levofloxacin was less common (13.3%). There was no relationship between antibiotic resistance and serotype distribution of the isolates. The epidemic serotype of P. aeruginosa from the mink hemorrhagic pneumonia in Shandong province was type G, which was a clone of commonly found in this province. These findings reveal the genetic similarities and antimicrobial susceptibility profiles of P. aeruginosa from clinical cases of mink hemorrhagic pneumonia and will facilitate the prevention and control of the disease in Shandong province of China. PMID:24629901

  7. Many factors complicate EM susceptibility tests

    NASA Astrophysics Data System (ADS)

    Richards, R. J.

    1982-09-01

    Procedures and apparatus currently employed for assaying the EM susceptibility of communication, navigation, and EW equipment are described. Susceptibility is examined in either conducted susceptibility tests, where signals are introduced into the input port of the device under test, or in radiated modes, where the entire device is exposed to an EM field to test for component and system failure. Noting that military standards require up to 10 times the EM resistance as commercial standards, the use of shielded enclosures in both commercial and military testing facilities is explored. RF-tight enclosures are filled with a homogeneous EM field produced by, optimally, broadband generators which emit signals which are amplified to desired levels. Sweep functions permit testing under broadband conditions. Attention is given to radiator selection and antenna choice to produce satisfactory test conditions at all frequencies.

  8. Antimicrobial Susceptibilities of Aeromonas spp. Isolated from Environmental Sources▿

    PubMed Central

    Huddleston, Jennifer R.; Zak, John C.; Jeter, Randall M.

    2006-01-01

    Aeromonas spp. are ubiquitous aquatic bacteria that cause serious infections in both poikilothermic and endothermic animals, including humans. Clinical isolates have shown an increasing incidence of antibiotic and antimicrobial drug resistance since the widespread use of antibiotics began. A total of 282 Aeromonas pure cultures were isolated from both urban and rural playa lakes in the vicinity of Lubbock, Texas, and several rivers in West Texas and New Mexico. Of these, at least 104 were subsequently confirmed to be independent isolates. The 104 isolates were identified by Biolog and belonged to 11 different species. The MICs of six metals, one metalloid, five antibiotics, and two antimicrobial drugs were determined. All aeromonads were sensitive to chromate, cobalt, copper, nickel, zinc, cefuroxime, kanamycin, nalidixic acid, ofloxacin, tetracycline, and sulfamethoxazole. Low incidences of trimethoprim resistance, mercury resistance, and arsenite resistance were found. Dual resistances were found in 5 of the 104 Aeromonas isolates. Greater numbers of resistant isolates were obtained from samples taken in March versus July 2002 and from sediment versus water. Plasmids were isolated from selected strains of the arsenite- and mercury-resistant organisms and were transformed into Escherichia coli XL1-Blue MRF′. Acquisition of the resistance phenotypes by the new host showed that these resistance genes were carried on the plasmids. Mercury resistance was found to be encoded on a conjugative plasmid. Despite the low incidence of resistant isolates, the six playa lakes and three rivers that were sampled in this study can be considered a reservoir for antimicrobial resistance genes. PMID:16950901

  9. Salmonella prevalence and antimicrobial susceptibility among dairy farm environmental samples collected in Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy cattle are a reservoir of several Salmonella serovars that are leading causes of human salmonellosis. The objectives of this study were to determine the environmental prevalence of Salmonella on dairy farms in Texas and to characterize the antimicrobial susceptibility of the isolates. Eleven...

  10. 21 CFR 866.1645 - Fully automated short-term incubation cycle antimicrobial susceptibility system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fully automated short-term incubation cycle antimicrobial susceptibility system. 866.1645 Section 866.1645 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY...

  11. 21 CFR 866.1645 - Fully automated short-term incubation cycle antimicrobial susceptibility system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fully automated short-term incubation cycle antimicrobial susceptibility system. 866.1645 Section 866.1645 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY...

  12. 21 CFR 866.1645 - Fully automated short-term incubation cycle antimicrobial susceptibility system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fully automated short-term incubation cycle antimicrobial susceptibility system. 866.1645 Section 866.1645 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY...

  13. 21 CFR 866.1645 - Fully automated short-term incubation cycle antimicrobial susceptibility system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fully automated short-term incubation cycle antimicrobial susceptibility system. 866.1645 Section 866.1645 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY...

  14. 21 CFR 866.1645 - Fully automated short-term incubation cycle antimicrobial susceptibility system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fully automated short-term incubation cycle antimicrobial susceptibility system. 866.1645 Section 866.1645 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY...

  15. [Serotype distribution and antimicrobial susceptibilities of Salmonella strains recovered from environmental samples between 2008-2014].

    PubMed

    Güleşen, Revasiye; Levent, Belkıs; Üvey, Mehmet; Bayrak, Hasan; Akgeyik, Mesut

    2016-07-01

    Despite the measures taken and control applications worldwide, Salmonella infections continue to threat the public health. Since these infections also cause significant economical loss, the salmonellas continue to be forefront globally. The determination of Salmonella serotypes and their sources is important for epidemiological point of view. In this study, serotype distribution and antimicrobial resistance of environmental isolates of Salmonella spp. recovered from the poultry farms, that were send for confirmation and serotyping between seven years period, 2008-2014, were evaluated. Strains isolated from environmental samples that were sent to Public Health Institute, Department of Microbiology Reference Laboratory, National Reference Laboratory for Enteric Pathogens, were inoculated onto Salmonella-Shigella and Xylose Lysine Desoxycholate agar and evaluated after 18-24 hours of incubation at 37°C. The identification of the strains was performed by using standard biochemical tests from the suspected colonies. Strains compatible with Salmonella spp. were serotyped using polyvalent and monovalent Salmonella O and H antisera by slide agglutination method. Antibiotic susceptibility tests were performed and evaluated according to CLSI recommendation using Kirby-Bauer disk diffusion method. In our study, a total of 2011 Salmonella strains were evaluated and 15 different serogroups and 75 different serotypes were identified. The most common Salmonella serotypes were S.Infantis (30.6%), followed by S.Enteritidis (21.8%), S.Typhimurium (6.5%), S.Kottbus (5.2%), S.Tennessee (4.3%), S.Mbandaka (4.1%), S.Indiana (3.9%), S.Kentucky (3%), S.Corvallis (2.5%), S.Paratyphi B (1.9%) and S.Hadar (1.7%). Among the isolates, 50.1% (1008/2011) were found susceptible to all of the tested antimicrobials. The rate of isolates that were resistant to only one drug was found to be 15.6%, whereas 30.9% of the strains showed multi-drug resistance (resistant to ≥ 3 antimicrobial drugs

  16. Antimicrobial susceptibility patterns of competitive exclusion bacteria applied to newly hatched chickens.

    PubMed

    Wagner, R Doug; Cerniglia, Carl E

    2005-07-25

    Competitive exclusion (CE) products are mixtures of obligate and facultative anaerobic bacteria applied to poultry hatchlings for prevention of Salmonella colonization. These mixtures have the potential to introduce bacteria with undesirable antimicrobial drug resistance traits into the human food supply. Antimicrobial drug susceptibilities of 27 obligate and facultative anaerobes isolated from a commercial CE product were evaluated with a microdilution minimal inhibitory concentration (MIC) assay. Bacteroides distasonis and Bacteroides fragilis isolates were resistant to tetracycline and other antimicrobial drugs. An Escherichia coli isolate was resistant to four antimicrobial drugs: erythromycin, penicillin, vancomycin, and tylosin. Erythromycin-resistant enterococci and vancomycin-resistant Lactococcus lactis isolates in the CE product were detected. These findings suggest that more work needs to be done to assess the potential effects of CE product use in poultry on the food supply. PMID:16014302

  17. Streptococcus agalactiae Serotype Distribution and Antimicrobial Susceptibility in Pregnant Women in Gabon, Central Africa.

    PubMed

    Belard, Sabine; Toepfner, Nicole; Capan-Melser, Mesküre; Mombo-Ngoma, Ghyslain; Zoleko-Manego, Rella; Groger, Mirjam; Matsiegui, Pierre-Blaise; Agnandji, Selidji T; Adegnika, Ayôla A; González, Raquel; Kremsner, Peter G; Menendez, Clara; Ramharter, Michael; Berner, Reinhard

    2015-01-01

    Neonatal invasive disease due to Streptococcus agalactiae is life threatening and preventive strategies suitable for resource limited settings are urgently needed. Protective coverage of vaccine candidates based on capsular epitopes will relate to local epidemiology of S. agalactiae serotypes and successful management of critical infections depends on timely therapy with effective antibiotics. This is the first report on serotype distribution and antimicrobial susceptibility of S. agalactiae in pregnant women from a Central African region. Serotypes V, III, and Ib accounted for 88/109 (81%) serotypes and all isolates were susceptible to penicillin and clindamycin while 13% showed intermediate susceptibility to erythromycin. PMID:26603208

  18. Streptococcus agalactiae Serotype Distribution and Antimicrobial Susceptibility in Pregnant Women in Gabon, Central Africa

    PubMed Central

    Belard, Sabine; Toepfner, Nicole; Capan-Melser, Mesküre; Mombo-Ngoma, Ghyslain; Zoleko-Manego, Rella; Groger, Mirjam; Matsiegui, Pierre-Blaise; Agnandji, Selidji T.; Adegnika, Ayôla A.; González, Raquel; Kremsner, Peter G.; Menendez, Clara; Ramharter, Michael; Berner, Reinhard

    2015-01-01

    Neonatal invasive disease due to Streptococcus agalactiae is life threatening and preventive strategies suitable for resource limited settings are urgently needed. Protective coverage of vaccine candidates based on capsular epitopes will relate to local epidemiology of S. agalactiae serotypes and successful management of critical infections depends on timely therapy with effective antibiotics. This is the first report on serotype distribution and antimicrobial susceptibility of S. agalactiae in pregnant women from a Central African region. Serotypes V, III, and Ib accounted for 88/109 (81%) serotypes and all isolates were susceptible to penicillin and clindamycin while 13% showed intermediate susceptibility to erythromycin. PMID:26603208

  19. Antimicrobial susceptibility of Clostridium perfringens strains isolated from broiler chickens

    PubMed Central

    Silva, R. O. S.; Salvarani, F.M.; Assis, R.A.; Martins, N.R.S.; Pires, P.S.; Lobato, F.C.F.

    2009-01-01

    Clostridium perfringens is a normal inhabitant of the intestinal tract of chickens as well as a potential pathogen that causes necrotic enteritis and colangio hepatitis. The minimum inhibitory concentration (MIC) of seven different compounds used for therapy, growth promotion or prevention of coccidiosis was determined by agar dilution method for 55 C. perfringens strains isolated from the intestines of broiler chickens. All strains showed high susceptibility to penicillin, avilamycin, monensin and narasin. Only 7.3% of the strains showed an intermediated sensitivity to lincomycin, and 49 (89.1%) were considered susceptible. For tetracycline and bacitracin, 41.8% and 47.3% of strains, respectively, were considered resistant. PMID:24031355

  20. Antimicrobial susceptibility of Clostridium perfringens strains isolated from broiler chickens.

    PubMed

    Silva, R O S; Salvarani, F M; Assis, R A; Martins, N R S; Pires, P S; Lobato, F C F

    2009-04-01

    Clostridium perfringens is a normal inhabitant of the intestinal tract of chickens as well as a potential pathogen that causes necrotic enteritis and colangio hepatitis. The minimum inhibitory concentration (MIC) of seven different compounds used for therapy, growth promotion or prevention of coccidiosis was determined by agar dilution method for 55 C. perfringens strains isolated from the intestines of broiler chickens. All strains showed high susceptibility to penicillin, avilamycin, monensin and narasin. Only 7.3% of the strains showed an intermediated sensitivity to lincomycin, and 49 (89.1%) were considered susceptible. For tetracycline and bacitracin, 41.8% and 47.3% of strains, respectively, were considered resistant. PMID:24031355

  1. Antimicrobial susceptibility of Arcanobacterium pyogenes isolated from the lungs of white-tailed deer (Odocoileus virginianus) with pneumonia.

    PubMed

    Tell, Lisa A; Brooks, Jason W; Lintner, Valerie; Matthews, Tammy; Kariyawasam, Subhashinie

    2011-09-01

    In vitro susceptibilities of 29 strains of Arcanobacterium pyogenes isolated from lung lesions of white-tailed deer (Odocoileus virginianus) with pneumonia were determined using the broth microdilution method to ascertain efficacious treatment options for pneumonic white-tailed deer. All 29 A. pyogenes strains tested were susceptible to ceftiofur, spectinomycin, tiamulin, and trimethoprim-sulfamethoxazole but were resistant to both danofloxacin and sulfadimethoxine. Likewise, all 29 isolates were either fully susceptible or intermediately susceptible to gentamicin (25 susceptible; 4 intermediate) and tulathromycin (25 susceptible; 4 intermediate). At least one isolate of A. pyogenes tested was resistant to ampicillin, chlortetracycline, clindamycin, enrofloxacin, florfenicol, oxytetracycline, penicillin, and tilmicosin suggesting their ineffectiveness in treating A. pyogenes-associated lung infections in white-tailed deer. Minimum inhibitory concentration (MIC) data for tylosin and neomycin could not be interpreted due to unavailability of Clinical and Laboratory Standards Institute (CLSI)-approved breakpoints for these 2 agents. In summary, based on MIC values, ceftiofur, spectinomycin, tiamulin, and trimethoprim-sulfamethoxazole are more efficacious than other antimicrobial agents for treating A. pyogenes-related pneumonia in white-tailed deer. However, ceftiofur may be preferred over the other 4 drugs as it is being widely used to treat respiratory disease in cattle and other animal species, as well as is available for single dose parenteral administration. PMID:21908365

  2. Antimicrobial susceptibility patterns, beta-lactamases, and biochemical identification of Yokenella regensburgei strains.

    PubMed

    Stock, Ingo; Sherwood, Kimberley J; Wiedemann, Bernd

    2004-01-01

    Yokenella regensburgei is an opportunistic human pathogen that phenotypically resembles Hafnia alvei. The susceptibility of 10 Y. regensburgei strains to 75 antimicrobial agents was examined, applying a microdilution procedure in cation-adjusted Mueller-Hinton broth (CAMHB) and IsoSensitest broth (ISB). beta-Lactamases were characterized phenotypically with beta-lactamase activity and induction assays. Genotypically, PCR experiments applying degenerated primer pairs for the detection of AmpC beta-lactamase genes were performed. Examining the phenotypic properties of Yokenella and 76 H. alvei strains with commercial identification systems and conventional tests, a database for an accurate biochemical separation of Y. regensburgei from H. alvei was established. In CAMHB, all tested yokenellae were resistant or at least of intermediate susceptibility to penicillin G, oxacillin, amoxicillin, amoxicillin-clavulanate, cefaclor, cefazoline, loracarbef, cefoxitin, all tested macrolides, lincosamides, streptogramins, ketolides, fusidic acid, glycopeptides, linezolid, and rifampicin. All Yokenella strains were sensitive to several beta-lactams, all tested aminoglycosides, chloramphenicol, folate-pathway inhibitors, fosfomycin, nitrofurantion, quinolones, and tetracyclines. In ISB, the minimum inhibitory concentration (MIC) values of several beta-lactams were one to four MIC doubling dilution steps lower than those found in CAMHB (depending on the beta-lactam). All yokenellae yielded specific amplification products for ampC, and all of these strains expressed beta-lactamases that were strongly inducible. Hydroxyproline amidase, maltosidase, tri-peptidase, proline deaminase, catalase reaction, Voges-Proskauer test, and fermentation of glycerol, melibiose and myo-inositol were suitable parameters to separate Y. regensburgei from H. alvei. PMID:14761716

  3. Antimicrobial susceptibilities of clinical isolates of Acinetobacter baumannii from Singapore.

    PubMed

    Kuah, B G; Kumarasinghe, G; Doran, J; Chang, H R

    1994-10-01

    The in vitro activities of 17 antimicrobial agents alone or in combination against 70 clinical isolates of Acinetobacter baumannii from Singapore were determined by broth microdilution. The MICs of amoxicillin, ampicillin, ceftazidime, ceftriaxone, gentamicin, and piperacillin for 90% of the strains were > or = 128 micrograms/ml. Addition of sulbactam to ampicillin produced improved activity, whereas adding tazobactam to piperacillin did not. The MICs of amikacin, ciprofloxacin, and imipenem for 90% of the strains were 32, 32, and 16 micrograms/ml, respectively. PMID:7840598

  4. Pathogenic bacteria profile and antimicrobial susceptibility patterns of ear infection at Bahir Dar Regional Health Research Laboratory Center, Ethiopia.

    PubMed

    Hailu, Derese; Mekonnen, Daniel; Derbie, Awoke; Mulu, Wondemagegn; Abera, Bayeh

    2016-01-01

    Ear infection linked with frequent antibiotic prescription, hearing impairment, severe disability and death is a public health threat in developing countries. However, there is scarcity of documented data in the study area. Therefore, this study aimed at determining bacterial etiologic agents and their antimicrobial susceptibility patterns among patients of all age groups referred to Bahir Dar Regional Health Research Laboratory Center. Retrospective data recorded on culture and antimicrobial susceptibility profile were retrieved for analysis. Pus swabs from discharging ears collected and processed for aerobic bacteria culture and susceptibility testing. Of the total 368 pus swab samples processed, 296 (80.4 %) were culture positive. Of which, 289 (97.6 %) were bacteria and 7 (2.4 %) were yeast cells. The proportion of ear infection was higher in males (92.7 %) than females (65 %) (P = 0.014). The frequency of ear infection below 21 years of age was 65.2 %. The predominant isolate was Pseudomonas aeruginosa (29.7 %) followed by Staphylococcus aureus (26.3 %) and Proteus spp. (21.9 %). High level of antimicrobial resistance rates were observed for amoxicillin/clavulanic acid, ampicillin and penicillin whereas ciprofloxacin, ceftriaxone, chloramphenicol, cotrimoxazole, gentamicin and amikacin were found effective against the isolated bacteria. Aerobic bacterial otitis media linked with high levels of resistance against amoxicillin/clavulanic acid and ampicillin is major health problem in the study area. Moreover, considerable level of oxacillin resistant S. aureus suggests the diffusion of methicillin resistant S. aureus in the community. Therefore, treatment of otitis media in the study area needs to be guided by antibiotic susceptibility testing of isolates. PMID:27119070

  5. Genetic diversity, virulence potential and antimicrobial susceptibility of Listeria monocytogenes recovered from different sources in India.

    PubMed

    Negi, Mamta; Vergis, Jess; Vijay, Deepthi; Dhaka, Pankaj; Malik, S V S; Kumar, Ashok; Poharkar, Krupali V; Doijad, Swapnil P; Barbuddhe, Sukhadeo B; Ramteke, Pramod W; Rawool, Deepak B

    2015-12-01

    Listeria monocytogenes isolates (n = 36) recovered from human and animal clinical cases and foods from different geographical regions of India were characterized using multiplex PCR-based serotyping, pulsed field gel electrophoresis (PFGE), in vitro and in vivo pathogenicity tests and antibiogram profiling. Multiplex PCR-based serotyping distributed L. monocytogenes isolates into 3 serogroups, of which 91.67% belonged to 4b, 4d, 4e serogroup, followed by 5.56% to 1/2a, 3a and 2.78% to 1/2b, 3b serogroups. PFGE analysis using ApaI and AscI restriction enzymes revealed 17 pulsotypes among 36 L. monocytogenes isolates with 6 major clusters having similar fingerprint profile within their cluster and 11 unique fingerprint profiles. Interestingly, PFGE analysis inferred that foods of animal origin could be a significant source of infection for spread of listeriosis among human populations. Furthermore, on comparison of in vitro and in vivo pathogenicity tests, an overall good correlation was observed between hemolytic titer assay and chick embryo inoculation test as most of the isolates with a hemolytic titer of ≥ 16 were found to be lethal to chick embryo. All the isolates were found to be susceptible to tested antimicrobials except for one animal isolate which showed resistance towards co-trimoxazole. PMID:26476275

  6. Altered Competitive Fitness, Antimicrobial Susceptibility, and Cellular Morphology in a Triclosan-Induced Small-Colony Variant of Staphylococcus aureus

    PubMed Central

    Forbes, Sarah; Latimer, Joe; Bazaid, Abdulrahman

    2015-01-01

    Staphylococcus aureus can produce small-colony variants (SCVs) that express various phenotypes. While their significance is unclear, SCV propagation may be influenced by relative fitness, antimicrobial susceptibility, and the underlying mechanism. We have investigated triclosan-induced generation of SCVs in six S. aureus strains, including methicillin-resistant S. aureus (MRSA). Parent strains (P0) were repeatedly passaged on concentration gradients of triclosan using a solid-state exposure system to generate P10. P10 was subsequently passaged without triclosan to generate X10. Susceptibility to triclosan and 7 antibiotics was assessed at all stages. For S. aureus ATCC 6538, SCVs were further characterized by determining microbicide susceptibility and competitive fitness. Cellular morphology was examined using electron microscopy, and protein expression was evaluated through proteomics. Triclosan susceptibility in all SCVs (which could be generated from 4/6 strains) was markedly decreased, while antibiotic susceptibility was significantly increased in the majority of cases. An SCV of S. aureus ATCC 6538 exhibited significantly increased susceptibility to all tested microbicides. Cross-wall formation was impaired in this bacterium, while expression of FabI, a target of triclosan, and IsaA, a lytic transglycosylase involved in cell division, was increased. The P10 SCV was 49% less fit than P0. In summary, triclosan exposure of S. aureus produced SCVs in 4/6 test bacteria, with decreased triclosan susceptibility but with generally increased antibiotic susceptibility. An SCV derived from S. aureus ATCC 6538 showed reduced competitive fitness, potentially due to impaired cell division. In this SCV, increased FabI expression could account for reduced triclosan susceptibility, while IsaA may be upregulated in response to cell division defects. PMID:26033734

  7. Data Mining Validation of Fluconazole Breakpoints Established by the European Committee on Antimicrobial Susceptibility Testing▿

    PubMed Central

    Cuesta, Isabel; Bielza, Concha; Larrañaga, Pedro; Cuenca-Estrella, Manuel; Laguna, Fernando; Rodriguez-Pardo, Dolors; Almirante, Benito; Pahissa, Albert; Rodríguez-Tudela, Juan L.

    2009-01-01

    European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints classify Candida strains with a fluconazole MIC ≤ 2 mg/liter as susceptible, those with a fluconazole MIC of 4 mg/liter as representing intermediate susceptibility, and those with a fluconazole MIC > 4 mg/liter as resistant. Machine learning models are supported by complex statistical analyses assessing whether the results have statistical relevance. The aim of this work was to use supervised classification algorithms to analyze the clinical data used to produce EUCAST fluconazole breakpoints. Five supervised classifiers (J48, Correlation and Regression Trees [CART], OneR, Naïve Bayes, and Simple Logistic) were used to analyze two cohorts of patients with oropharyngeal candidosis and candidemia. The target variable was the outcome of the infections, and the predictor variables consisted of values for the MIC or the proportion between the dose administered and the MIC of the isolate (dose/MIC). Statistical power was assessed by determining values for sensitivity and specificity, the false-positive rate, the area under the receiver operating characteristic (ROC) curve, and the Matthews correlation coefficient (MCC). CART obtained the best statistical power for a MIC > 4 mg/liter for detecting failures (sensitivity, 87%; false-positive rate, 8%; area under the ROC curve, 0.89; MCC index, 0.80). For dose/MIC determinations, the target was >75, with a sensitivity of 91%, a false-positive rate of 10%, an area under the ROC curve of 0.90, and an MCC index of 0.80. Other classifiers gave similar breakpoints with lower statistical power. EUCAST fluconazole breakpoints have been validated by means of machine learning methods. These computer tools must be incorporated in the process for developing breakpoints to avoid researcher bias, thus enhancing the statistical power of the model. PMID:19433568

  8. Antimicrobial susceptibility of Mycoplasma bovis isolates from veal calves and dairy cattle in the Netherlands.

    PubMed

    Heuvelink, Annet; Reugebrink, Constance; Mars, Jet

    2016-06-30

    Control of Mycoplasma bovis infections depends on good husbandry practices and antibiotic treatment. To allow more prudent use of antimicrobial drugs, there is a need for information on the susceptibility profile of this pathogen. The objective of the present study was to analyse the in vitro antimicrobial susceptibility of clinical M. bovis isolates in the Netherlands. The collection comprised 95 bovine isolates, originating from lungs (n=56), mastitis milk (n=27), and synovial fluid (n=12), collected between 2008 and 2014. Minimal inhibitory concentrations (MICs) were assessed by broth microdilution, both by using in-house prepared MIC plates and by using commercially available MIC plates. For each antimicrobial agent, the range of MIC results, the MIC50, and MIC90 values were calculated. M. bovis strains recently isolated in the Netherlands appeared to be characterized by relatively high MIC values for antimicrobial agents that, until now, have been recommended by the Dutch Association of Veterinarians for treating pneumonia caused by Mycoplasma species. Fluoroquinolones appeared to be the most efficacious in inhibiting M. bovis growth, followed by tulathromycin and oxytetracycline. The highest MIC values were obtained for erythromycin, tilmicosin, and tylosin. Future studies should be done on determining M. bovis specific clinical breakpoints, standardization of methods to determine MIC values as well as molecular studies on detection of antimicrobial resistance mechanisms of M. bovis isolates to develop PCR assays for determining resistance. PMID:27259820

  9. Antimicrobial susceptibility of clinical isolates of Serratia marcescens.

    PubMed Central

    Alvarez, J S; Regueiro, B; Garrido, M J

    1979-01-01

    The in vitro susceptibilities of 242 isolates of Serratia marcescens to 17 antibacterial drugs have been determined. Oxolinic acid, nalidixic acid, cefoxitin, and amikacin were the most active drugs. Ampicillin, kanamycin, and cephalothin were among the least active. A 4-year study showed that resistance of S. marcescens to dibekacin, tobramycin, sisomycin, and gentamicin has increased at least one order of magnitude in that period, whereas resistance to amikacin showed but a twofold increase. PMID:391150

  10. Effects of a Chlorhexidine Gluconate-Containing Mouthwash on the Vitality and Antimicrobial Susceptibility of In Vitro Oral Bacterial Ecosystems

    PubMed Central

    McBain, Andrew J.; Bartolo, Robert G.; Catrenich, Carl E.; Charbonneau, Duane; Ledder, Ruth G.; Gilbert, Peter

    2003-01-01

    Oral bacterial microcosms, established using saliva inocula from three individuals, were maintained under a feast-famine regime within constant-depth film fermenters. Steady-state communities were exposed four times daily, postfeeding, to a chlorhexidine (CHX) gluconate-containing mouthwash (CHXM) diluted to 0.06% (wt/vol) antimicrobial content. The microcosms were characterized by heterotrophic plate counts and PCR-denaturing gradient gel electrophoresis (DGGE). CHXM caused significant decreases in both total anaerobe and total aerobe/facultative anaerobe counts (P < 0.05), together with lesser decreases in gram-negative anaerobes. The degree of streptococcal and actinomycete inhibition varied considerably among individuals. DGGE showed that CHXM exposure caused considerable decreases in microbial diversity, including marked reductions in Prevotella sp. and Selenomonas infelix. Pure-culture studies of 10 oral bacteria (eight genera) showed that Actinomyces naeslundii, Veillonella dispar, Prevotella nigrescens, and the streptococci were highly susceptible to CHX, while Lactobacillus rhamnosus, Fusobacterium nucleatum, and Neisseria subflava were the least susceptible. Determination of the MICs of triclosan, CHX, erythromycin, penicillin V, vancomycin, and metronidazole for microcosm isolates, before and after 5 days of CHXM exposure, showed that CHXM exposure altered the distribution of isolates toward those that were less susceptible to CHX (P < 0.05). Changes in susceptibility distributions for the other test agents were not statistically significant. In conclusion, population changes in plaque microcosms following repeated exposure to CHXM represented an inhibition of the most susceptible flora with a clonal expansion of less susceptible species. PMID:12902270

  11. Effects of a chlorhexidine gluconate-containing mouthwash on the vitality and antimicrobial susceptibility of in vitro oral bacterial ecosystems.

    PubMed

    McBain, Andrew J; Bartolo, Robert G; Catrenich, Carl E; Charbonneau, Duane; Ledder, Ruth G; Gilbert, Peter

    2003-08-01

    Oral bacterial microcosms, established using saliva inocula from three individuals, were maintained under a feast-famine regime within constant-depth film fermenters. Steady-state communities were exposed four times daily, postfeeding, to a chlorhexidine (CHX) gluconate-containing mouthwash (CHXM) diluted to 0.06% (wt/vol) antimicrobial content. The microcosms were characterized by heterotrophic plate counts and PCR-denaturing gradient gel electrophoresis (DGGE). CHXM caused significant decreases in both total anaerobe and total aerobe/facultative anaerobe counts (P < 0.05), together with lesser decreases in gram-negative anaerobes. The degree of streptococcal and actinomycete inhibition varied considerably among individuals. DGGE showed that CHXM exposure caused considerable decreases in microbial diversity, including marked reductions in Prevotella sp. and Selenomonas infelix. Pure-culture studies of 10 oral bacteria (eight genera) showed that Actinomyces naeslundii, Veillonella dispar, Prevotella nigrescens, and the streptococci were highly susceptible to CHX, while Lactobacillus rhamnosus, Fusobacterium nucleatum, and Neisseria subflava were the least susceptible. Determination of the MICs of triclosan, CHX, erythromycin, penicillin V, vancomycin, and metronidazole for microcosm isolates, before and after 5 days of CHXM exposure, showed that CHXM exposure altered the distribution of isolates toward those that were less susceptible to CHX (P < 0.05). Changes in susceptibility distributions for the other test agents were not statistically significant. In conclusion, population changes in plaque microcosms following repeated exposure to CHXM represented an inhibition of the most susceptible flora with a clonal expansion of less susceptible species. PMID:12902270

  12. Clostridium perfringens and Clostridium difficile in cooked beef sold in Côte d'Ivoire and their antimicrobial susceptibility.

    PubMed

    Kouassi, Kra Athanase; Dadie, Adjéhi Thomas; N'Guessan, Kouadio Florent; Dje, Koffi Marcellin; Loukou, Yao Guillaume

    2014-08-01

    The aim of this study was to evaluate the prevalence of Clostridium difficile and Clostridium perfringens in cooked beef sold in the streets in Côte d'Ivoire and their antimicrobial susceptibility. A total of 395 kidney and flesh samples of cooked beef were collected from vendors at Abidjan and subjected to C. difficile and C. perfringens isolation and identification by using biochemical tests, API 20A system and PCR detection. Subsequently, the antimicrobial susceptibility test was performed for confirmed isolates. Our results showed the prevalence of 12.4% for C. difficile (11.04% in kidney and 13.45% in flesh) and 5.06% for C. perfringens (2.32% in kidney and 7.17% in flesh). Metronidazole and vancomycin remained the most potent antimicrobial agents against C. difficile while metronidazole and penicillin G were the most potent agents against C. perfringens. The resistance rates to tetracycline, doxycycline, chloramphenicol and erythromycin against C. difficile and C. perfringens isolates ranged from 2.05% to 8.16% and from 20% to 50%, respectively. Among all antimicrobial agents tested against C. difficile, percentages of resistance to quinolones ciprofloxacin, norfloxacin and nalidixic acid as well as to gentamicin and cefotaxime were the highest. Eight resistant phenotypes were defined for C. difficile isolates and eleven resistant phenotypes for C. perfringens isolates. Clindamycin/gentamicin/cefotaxime/ciprofloxacin/norfloxacin/nalidixic acid resistance was the most common phenotype for C. difficile (55.10% of isolates) while norfloxacin/nalidixic acid resistance was the most common phenotype for C. perfringens (20% of isolates). PMID:24944124

  13. Antimicrobial susceptibility and analysis of macrolide resistance genes in Streptococcus pneumoniae isolated in Hamadan

    PubMed Central

    Mosleh, Mohammad Najafi; Gharibi, Marzieh; Alikhani, Mohammad Yousef; Saidijam, Massoud; Vakhshiteh, Faezeh

    2014-01-01

    Objective(s): Macrolide resistant Streptococcus pneumoniae pose an emerging problem globally. The aim of this study was to investigate the prevalence of ermB and mefA genes (macrolide resistant genes) by polymerase chain reaction (PCR) method and to detect drug resistance patterns of S. pneumoniae isolated from clinical samples to macrolides and other antibiotic agents by E-test method. Materials and Methods: Fifty five isolates of S. pneumoniae were obtained from clinical samples with microbial tests. The antibiotic susceptibility of isolates for erythromycin, azithromycin, clarithromycin, ceftazidime, ciprofloxacin and vancomycin were determined by E-test method. Genotypic antibiotic resistance pattern was determined by PCR with primer designed for ermB and mefA genes. Results: The number of S. pneumoniae isolates resistance to erythromycin, azithromycin, clarithromycin, ceftazidim, ciprofloxacin were 25.5%, 18.2%, 16.4%, 21.8% and 10.9%, respectively while no resistance to vancomycin was observed. The macrolide resistance genes of ermB and mefA were found in 10.9% and 18.2% of the isolates, respectively. Conclusion: The result of the current study suggests the necessity of evaluation the changes in MIC (minimum inhibitory concentration) values as well as genetic mutations to estimate the prevalence of the resistance antimicrobial agents in S. pneumoniae. PMID:25422753

  14. Meat industry wastewater: microbiological quality and antimicrobial susceptibility of E. coli and Salmonella sp. isolates, case study in Vojvodina, Serbia.

    PubMed

    Stošić, Milena; Čučak, Dragana; Kovačević, Srđan; Perović, Marija; Radonić, Jelena; Turk Sekulić, Maja; Vojinović Miloradov, Mirjana; Radnović, Dragan

    2016-01-01

    Wastewater from meat processing industries is a fusion of compounds with a high load of organic matter, and pathogen microorganisms like Escherichia coli, and Salmonella sp. The aim of this research was to determine microbiological characteristics of the wastewater discharged from the meat processing industry in order to get a more detailed insight into meat industry wastewater pollution, and to evaluate the resistance of bacterial strains E. coli and Salmonella sp. to antibiotics. The evaluation of the antimicrobial susceptibility was performed on 37 strains of E. coli and eight strains of Salmonella sp. to nine different antibiotics. The number of faecal pollution indicators was very high in all samples. From a total of 37 strains of E. coli, a moderate degree of resistance was shown to tetracycline (37.83%); a low degree of resistance to ampicillin (21.62%), streptomycin (24.32%), trimethoprim-sulfamethoxazol (18.92%) and nalidixic acid (16.22%); and very low to: chloramphenicol (13.51%), ciprofloxacin (2.7%), gentamicin and cefotaxime (0.0%). The results for eight strains of Salmonella sp. show that all eight isolates had some degree of susceptibility to nine tested antimicrobial agents and six strains were fully susceptible to all tested antibiotics. PMID:27191574

  15. Antimicrobial susceptibility of Clostridium perfringens isolated from piglets with or without diarrhea in Brazil

    PubMed Central

    Salvarani, Felipe Masiero; Silveira Silva, Rodrigo Otávio; Pires, Prhiscylla Sadanã; da Costa Cruz Júnior, Eduardo Coulaud; Albefaro, Isabella Silva; de Carvalho Guedes, Roberto Maurício; Faria Lobato, Francisco Carlos

    2012-01-01

    The minimum inhibitory concentration (MIC) was determined for 13 antibiotics against Clostridium perfringens isolated from Brazilian piglets. The collection of isolates was performed in June to October 2010. All isolates were susceptible to amoxicillin and ceftiofur, whereas most were resistant to tetracycline and lincomycin. Avilamycin and narasin were more effective against isolates from non-diarrheic than from diarrheic piglets. The other antimicrobials were less active in need of high concentrations to inhibit the growth of the C. perfringens type A. These results suggest the need for further studies evaluating molecular factors related to the antimicrobial resistance of C. perfringens. PMID:24031924

  16. Diversity and antimicrobial susceptibility profiling of staphylococci isolated from bovine mastitis cases and close human contacts.

    PubMed

    Schmidt, T; Kock, M M; Ehlers, M M

    2015-09-01

    The objectives of this study were to examine the diversity of Staphylococcus spp. recovered from bovine intramammary infections and humans working in close contact with the animals and to evaluate the susceptibility of the staphylococcal isolates to different antimicrobials. A total of 3,387 milk samples and 79 human nasal swabs were collected from 13 sampling sites in the KwaZulu-Natal province of South Africa. In total, 146 Staph. aureus isolates and 102 coagulase-negative staphylococci (CNS) were recovered from clinical and subclinical milk samples. Staphylococcusaureus was isolated from 12 (15.2%) of the human nasal swabs and 95 representative CNS were recovered for further characterization. The CNS were identified using multiplex-PCR assays, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and tuf gene sequencing. Seven Staphylococcus spp. were identified among the CNS of bovine origin, with Staph.chromogenes (78.4%) predominating. The predominant CNS species recovered from the human nasal swabs was Staph.epidermidis (80%) followed by Staph.chromogenes (6.3%). The antimicrobial susceptibility of all staphylococcal isolates was evaluated using disk diffusion and was supplemented by screening for specific antimicrobial resistance genes. Ninety-eight (67.1%) Staph.aureus isolates of bovine origin were pansusceptible; 39 (26.7%) isolates were resistant to a single class, and 7 (4.8%) isolates were resistant to 2 classes of antimicrobials. Two Staph. aureus (1.4%) isolates were multidrug-resistant. Resistance to penicillin was common, with 28.8% of the bovine and 75% of the human Staph. aureus isolates exhibiting resistance. A similar observation was made with the CNS, where 37.3% of the bovine and 89.5% of the human isolates were resistant to penicillin. Multidrug-resistance was common among the human CNS, with 39% of the isolates exhibiting resistance to 3 or more classes of antimicrobials. The antimicrobial

  17. Nasopharyngeal Carriage, Capsular and Molecular Serotyping and Antimicrobial Susceptibility of Streptococcus pneumoniae among Asymptomatic Healthy Children in Egypt.

    PubMed

    El-Nawawy, Ahmed A; Hafez, Soad F; Meheissen, Marwa A; Shahtout, Nehal M; Mohammed, Essam E

    2015-12-01

    Streptococcus pneumoniae is a major cause of childhood morbidity and mortality worldwide with increasing antimicrobial resistance. 600 randomly chosen asymptomatic healthy children aged 2-60 months attending Alexandria University Children's Hospital were evaluated for prevalence of nasopharyngeal (NP) carriage of S. pneumoniae. Prevalence of NP carriage was 29.2% (n = 175/600) Capsular serotyping was done using Quellung reaction. Vaccine covered serotypes (VST) represented 67.4% while non-vaccine serotypes (NVST) were 32.6%. The most common VST isolated were 19F (24.6%), 6B (14.3%) and 6A (10.9%). Confirmation of serotyping was performed by multiplex PCR which showed 100% concordance with the Quellung reaction. Antimicrobial susceptibility testing showed penicillin non-susceptibility of 15% (using non-meningitis penicillin MIC breakpoints) and 55% (using meningitis penicillin MIC breakpoints). Highest resistance was found in sulphamethoxazole-trimethoprim (55%), tetracyclins (49%), erythromycin (40%) and clindamycin (25%). This study revealed the epidemiological importance to evaluate regularly the prevalence, serotypes and the increasing antimicrobial resistance of S. pneumoniae in the community. PMID:26428194

  18. Urinary Escherichia coli antimicrobial susceptibility profiles and their relationship with community antibiotic use in Tasmania, Australia.

    PubMed

    Meumann, Ella M; Mitchell, Brett G; McGregor, Alistair; McBryde, Emma; Cooley, Louise

    2015-10-01

    This study assessed urinary Escherichia coli antibiotic susceptibility patterns in Tasmania, Australia, and examined their association with community antibiotic use. The susceptibility profiles of all urinary E. coli isolates collected in Tasmania between January 2010 and December 2012 were included. The amount of Pharmaceutical Benefits Scheme (PBS)-subsidised use of amoxicillin, amoxicillin/clavulanic acid (AMC), cefalexin, norfloxacin, ciprofloxacin and trimethoprim was retrieved (at the Tasmanian population level) and the number of defined daily doses per 1000 population per day in Tasmania for these antibiotics was calculated for each month during the study period. Antimicrobial susceptibility data were assessed for changes over time in the 3-year study period. Antimicrobial use and susceptibility data were assessed for seasonal differences and lag in resistance following antibiotic use. Excluding duplicates, 28145 E. coli isolates were included. Resistance levels were low; 35% of isolates were non-susceptible to amoxicillin, 14% were non-susceptible to trimethoprim and <5% were non-susceptible to AMC, cefalexin, gentamicin and norfloxacin. Amoxicillin use increased by 35% during winter/spring compared with summer/autumn, and AMC use increased by 21%. No seasonal variation in quinolone use or resistance was detected. The low levels of antimicrobial resistance identified may relate to Tasmania's isolated geographical location. Significant seasonal variation in amoxicillin and AMC use is likely to be due to increased use of these antibiotics for treatment of respiratory tract infections in winter. Quinolone use is restricted by the PBS in Australia, which is the likely explanation for the low levels of quinolone use and resistance identified. PMID:26187365

  19. Antimicrobial Susceptibility and Clonality of Clinical Ureaplasma Isolates in the United States.

    PubMed

    Fernández, Javier; Karau, Melissa J; Cunningham, Scott A; Greenwood-Quaintance, Kerryl E; Patel, Robin

    2016-08-01

    Ureaplasma urealyticum and Ureaplasma parvum are pathogens involved in urogenital tract and intrauterine infections and also in systemic diseases in newborns and immunosuppressed patients. There is limited information on the antimicrobial susceptibility and clonality of these species. In this study, we report the susceptibility of 250 contemporary isolates of Ureaplasma (202 U. parvum and 48 U. urealyticum isolates) recovered at Mayo Clinic, Rochester, MN. MICs of doxycycline, azithromycin, ciprofloxacin, tetracycline, erythromycin, and levofloxacin were determined by broth microdilution, with MICS of the last three interpreted according to CLSI guidelines. Levofloxacin resistance was found in 6.4% and 5.2% of U. parvum and U. urealyticum isolates, respectively, while 27.2% and 68.8% of isolates, respectively, showed ciprofloxacin MICs of ≥4 μg/ml. The resistance mechanism of levofloxacin-resistant isolates was due to mutations in parC, with the Ser83Leu substitution being most frequent, followed by Glu87Lys. No macrolide resistance was found among the 250 isolates studied; a single U. parvum isolate was tetracycline resistant. tet(M) was found in 10 U. parvum isolates, including the single tetracycline-resistant isolate, as well as in 9 isolates which had low tetracycline and doxycycline MICs. Multilocus sequence typing (MLST) performed on a selection of 46 isolates showed high diversity within the clinical Ureaplasma isolates studied, regardless of antimicrobial susceptibility. The present work extends previous knowledge regarding susceptibility to antimicrobial agents, resistance mechanisms, and clonality of Ureaplasma species in the United States. PMID:27246773

  20. Antimicrobial susceptibilities of enterococci isolated from hospitalized patients.

    PubMed Central

    Venditti, M; Tarasi, A; Gelfusa, V; Nicastri, E; Penni, A; Martino, P

    1993-01-01

    One hundred and one isolates of Enterococcus species isolated recently from hospitalized patients were evaluated in vitro for antibiotic susceptibility. Teicoplanin and mideplanin were the most active agents, followed by ramoplanin, vancomycin, ciprofloxacin, ampicillin, and imipenem. High-level resistance to gentamicin (MIC > 500 micrograms/ml) and/or streptomycin (MIC > 2,000 micrograms/ml) was found in 60 isolates. High-level resistance to ampicillin (MIC > or = 16 micrograms/ml) was found in 17 isolates. MBC studies revealed that ramoplanin possesses significant bactericidal activity. PMID:8517714

  1. Antimicrobial susceptibility of Treponema phagedenis-like spirochetes isolated from dairy cattle with papillomatous digital dermatitis lesions in Japan.

    PubMed

    Yano, Takahisa; Moe, Kyaw Kyaw; Chuma, Takehisa; Misawa, Naoaki

    2010-03-01

    The minimal inhibitory concentrations (MICs) of 23 Treponema phagedenis-like spirochetes isolated from dairy cattle with papillomatous digital dermatitis (PDD) lesions in Japan were investigated by a broth microdilution method using 15 antimicrobial agents. Although all MIC values showed a monomodal distribution, the MICs of the antimicrobial agents for 90% (MIC(90)) of the isolates tested varied among the agents examined. The MIC(90) values for penicillin G, ampicillin, and erythromycin were <0.06 microg/ml. In contrast, the MIC(90) values for kanamycin, streptomycin, rifampicin, sulfamethoxazole, trimethoprim, and colistin were >128 microg/ml. Oxytetracycline, lincomycin, enrofloxacin, chloramphenicol, ceftiofur, and gentamicin showed intermediate values, i.e., 0.5~32 microg/ml. The present study suggested that no isolate had acquired resistance to the antimicrobial agents examined, although they may have natural resistance to some agents. Furthermore, the in vitro antimicrobial susceptibility data would provide helpful information for PDD treatment and the development of a selective medium for isolating the organism effectively. PMID:19996562

  2. Accurate detection of Neisseria gonorrhoeae ciprofloxacin susceptibility directly from genital and extragenital clinical samples: towards genotype-guided antimicrobial therapy

    PubMed Central

    Pond, Marcus J.; Hall, Catherine L.; Miari, Victoria F.; Cole, Michelle; Laing, Ken G.; Jagatia, Heena; Harding-Esch, Emma; Monahan, Irene M.; Planche, Timothy; Hinds, Jason; Ison, Catherine A.; Chisholm, Stephanie; Butcher, Philip D.; Sadiq, Syed Tariq

    2016-01-01

    Introduction Increasing use of nucleic acid amplification tests (NAATs) as the primary means of diagnosing gonococcal infection has resulted in diminished availability of Neisseria gonorrhoeae antimicrobial susceptibility data. We conducted a prospective diagnostic assessment of a real-time PCR assay (NGSNP) enabling direct detection of gonococcal ciprofloxacin susceptibility from a range of clinical sample types. Methods NGSNP, designed to discriminate an SNP associated with ciprofloxacin resistance within the N. gonorrhoeae genome, was validated using a characterized panel of geographically diverse isolates (n = 90) and evaluated to predict ciprofloxacin susceptibility directly on N. gonorrhoeae-positive NAAT lysates derived from genital (n = 174) and non-genital (n = 116) samples (n = 290), from 222 culture-confirmed clinical episodes of gonococcal infection. Results NGSNP correctly genotyped all phenotypically susceptible (n = 49) and resistant (n = 41) panel isolates. Ciprofloxacin-resistant N. gonorrhoeae was responsible for infection in 29.7% (n = 66) of clinical episodes evaluated. Compared with phenotypic susceptibility testing, NGSNP demonstrated sensitivity and specificity of 95.8% (95% CI 91.5%–98.3%) and 100% (95% CI 94.7%–100%), respectively, for detecting ciprofloxacin-susceptible N. gonorrhoeae, with a positive predictive value of 100% (95% CI 97.7%–100%). Applied to urogenital (n = 164), rectal (n = 40) and pharyngeal samples alone (n = 30), positive predictive values were 100% (95% CI 96.8%–100%), 100% (95% CI 87.2%–100%) and 100% (95% CI 82.4%–100%), respectively. Conclusions Genotypic prediction of N. gonorrhoeae ciprofloxacin susceptibility directly from clinical samples was highly accurate and, in the absence of culture, will facilitate use of tailored therapy for gonococcal infection, sparing use of current empirical treatment regimens and enhancing acquisition of susceptibility data for

  3. Resistance mechanisms and drug susceptibility testing of nontuberculous mycobacteria.

    PubMed

    van Ingen, Jakko; Boeree, Martin J; van Soolingen, Dick; Mouton, Johan W

    2012-06-01

    Nontuberculous mycobacteria (NTM) are increasingly recognized as causative agents of opportunistic infections in humans. For most NTM infections the therapy of choice is drug treatment, but treatment regimens differ by species, in particular between slow (e.g. Mycobacterium avium complex, Mycobacterium kansasii) and rapid growers (e.g. Mycobacterium abscessus, Mycobacterium fortuitum). In general, drug treatment is long, costly, and often associated with drug-related toxicities; outcome of drug treatment is poor and is likely related to the high levels of natural antibiotic resistance in NTM. The role of drug susceptibility testing (DST) in the choice of agents for antimicrobial treatment of NTM disease, mainly that by slow growers, remains subject of debate. There are important discrepancies between drug susceptibility measured in vitro and the activity of the drug observed in vivo. In part, these discrepancies derive from laboratory technical issues. There is still no consensus on a standardized method. With the increasing clinical importance of NTM disease, DST of NTM is again in the spotlight. This review provides a comprehensive overview of the mechanisms of drug resistance in NTM, phenotypic methods for testing susceptibility in past and current use for DST of NTM, as well as molecular approaches to assess drug resistance. PMID:22525524

  4. Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from retail shrimps in Malaysia

    PubMed Central

    Letchumanan, Vengadesh; Yin, Wai-Fong; Lee, Learn-Han; Chan, Kok-Gan

    2015-01-01

    Vibrio parahaemolyticus is a marine and estuarine bacterium that has been the leading cause of foodborne outbreaks which leads to a significant threat to human health worldwide. Consumption of seafood contaminated with V. parahaemolyticus causes acute gastroenteritis in individuals. The bacterium poses two main virulence factor including the thermostable direct hemolysin (tdh) which is a pore-forming protein that contributes to the invasiveness of the bacterium in humans and TDH-related hemolysin (trh), which plays a similar role as tdh in the disease pathogenesis. This study aimed to investigate the antimicrobial resistance V. parahaemolyticus strains in shrimps purchased from wetmarkets and supermarkets. The toxR-based PCR assay indicated that a total of 57.8% (185/320) isolates were positive for V. parahaemolyticus. Only 10% (19/185) toxR-positive isolate exhibit the trh gene and none of the isolates were tested positive for tdh. The MAR index was measured for 14 common antimicrobial agents. The results indicated 98% of the isolates were highly susceptible to imipenem, ampicillin sulbactam (96%), chloramphenicol (95%), trimethoprim-sulfamethoxazole (93%), gentamicin (85%), levofloxacin (83%), and tetracycline (82%). The chloramphenicol (catA2) and kanamycin (aphA-3) resistance genes were detected in the resistant V. parahaemolyticus isolates. Our results demonstrate that shrimps are contaminated with V. parahaemolyticus, some of which carry the trh-gene thus being potential to cause food borne illness. The occurrence of multidrug resistance strains in the environment could be an indication of excessive usage of antibiotics in agriculture and aquaculture fields. PMID:25688239

  5. Distribution of Salmonella serovars and antimicrobial susceptibility of Salmonella Enteritidis from poultry in Zimbabwe.

    PubMed

    Makaya, P V; Matope, G; Pfukenyi, D M

    2012-01-01

    A study was carried out to determine the distribution and antimicrobial susceptibility profiles of Salmonella serovars from chickens from large-scale commercial (LSC), small-scale commercial (SSC), and rural free-range (RFR) farms of Zimbabwe. Pooled cloacal swabs were collected for culture and isolation of Salmonella spp. A chi-square test was used to assess distribution differences of salmonellas among the farming sectors. Approximately 10% (283/2833) of the swabs were positive for Salmonella enterica, with only subspecies enterica (98.6%) and arizonae (1.4%) being detected. The prevalence of S. enterica varied significantly (P<0.05) among areas, with Harare (27.8%) and Buhera (1.3%) recording the highest and the least prevalence, respectively. S. enterica was only isolated from LSC and SSC farms, with the former having a significantly (P<0.001; χ(2)=155.3) higher prevalence than the latter. S. arizonae was only isolated from the SSC farms while none were obtained from the RFR farms. The serovars isolated were Salmonella Enteritidis (72.8%), Group C (20.1%), Group B (4.2%), Salmonella Typhimurium (1.1%) and Salmonella Gallinarum (0.4%). S. Enteritidis predominated in the urban/periurban areas. Approximately 26% (53/206) of S. Enteritidis isolates were resistant to one or more antimicrobial agents. Resistance to tetracycline was the most common, while no resistance was detected for furazolidone, neomycin and trimethoprim-sulfamethoxazole. There were 12.1% multi-drug-resistant S. Enteritidis isolates, and the resistance to ampicillin/kanamycin was predominant. The identification of multi-drug-resistant S. Enteritidis is of public health concern. Thus, stringent control of S. Enteritidis will reduce the public health risk of human salmonellosis. PMID:22515540

  6. In vitro drug susceptibility of 40 international reference rapidly growing mycobacteria to 20 antimicrobial agents

    PubMed Central

    Pang, Hui; Li, Guilian; Wan, Li; Jiang, Yi; Liu, Haican; Zhao, Xiuqin; Zhao, Zhongfu; Wan, Kanglin

    2015-01-01

    Rapidly growing mycobacteria (RGM) are human pathogens that are relatively easily identified by acid-fast staining but are proving difficult to treat in the clinic. In this study, we performed susceptibility testing of 40 international reference RGM species against 20 antimicrobial agents using the cation-adjusted Mueller-Hinton (CAMH) broth microdilution based on the minimum inhibitory concentration (MIC) assay recommended by the guidelines of the Clinical and Laboratory Standards Institute (CLSI). The results demonstrated that RGM organisms were resistant to the majority of first-line antituberculous agents but not to second-line fluoroquinolones or aminoglycosides. Three drugs (amikacin, tigecycline and linezolid) displayed potent antimycobacterial activity against all tested strains. Capreomycin, levofloxacin and moxifloxacin emerged as promising candidates for the treatment of RGM infections, and cefoxitin and meropenem were active against most strains. Mycobacterium chelonae (M. chelonae), M. abscessus, M. bolletii, M. fortuitum, M. boenickei, M. conceptionense, M. pseudoshottsii, M. septicum and M. setense were the most resistant RGM species. These results provide significant insight into the treatment of RGM species and will assist optimization of clinical criteria. PMID:26629031

  7. Phenotypic antimicrobial susceptibility and occurrence of selected resistance genes in gram-positive mastitis pathogens isolated from Wisconsin dairy cows.

    PubMed

    Ruegg, P L; Oliveira, L; Jin, W; Okwumabua, O

    2015-07-01

    In the United States, few intramammary antimicrobials exist that are approved for treatment of bovine mastitis; thus, ensuring judicious use of these products is a priority. The objectives of this study were to determine phenotypic susceptibility and presence of selected antimicrobial resistance genes from staphylococci, streptococci, and streptococcal-like organisms recovered from cases of clinical mastitis occurring in cows on large Wisconsin farms. Staphylococcus aureus (n=35 from 19 herds), coagulase-negative staphylococci (n=51 from 30 herds), Streptococcus spp. (n=78 from 36 herds), and streptococcal-like organisms (n=31 from 19 herds) were used in this study. All Staphylococcus spp. were susceptible to ceftiofur, cephalothin, and the combination of penicillin and novobiocin. Of all staphylococci, only a single Staphylococcus epidermidis exhibited phenotypic resistance to oxacillin. Phenotypic susceptibility to erythromycin was observed in only 8.6 and 15.7% of Staphylococcus aureus and coagulase-negative staphylococci, respectively. Approximately 20% of staphylococci and 13 to 22% of streptococci and streptococcal-like organisms exhibited phenotypic resistance to pirlimycin. All Streptococcus spp. exhibited phenotypic susceptibility to ceftiofur, cephalothin, and oxacillin. The proportion of isolates exhibiting phenotypic susceptibility to pirlimycin and sulfadimethoxine differed among Streptococcus dysgalactiae and Streptococcus uberis. All streptococcal-like organisms exhibited phenotypic susceptibility to ceftiofur, cephalothin, oxacillin, penicillin, and the combination of penicillin and novobiocin. Of all organisms tested, 36.9% did not carry any of the resistance genes (ermC, blaZ, tetK, or tetM), 35.4% carried 1 gene, and 27.7% carried multiple genes (usually blaZ in combination with a tet gene). Eighteen (51.4%) Staph. aureus and 12 (48.0%) Staphylococcus chromogenes carried multiple resistance genes. Six (12.2%) Strep. dysgalactiae and no Strep

  8. Prevalence, serovars and antimicrobial susceptibility of Salmonella spp. from wild and domestic green iguanas (Iguana iguana) in Grenada, West Indies.

    PubMed

    Sylvester, W R B; Amadi, V; Pinckney, R; Macpherson, C N L; McKibben, J S; Bruhl-Day, R; Johnson, R; Hariharan, H

    2014-09-01

    Cloacal swabs from 62 green iguanas (Iguana iguana), including 47 wild and 15 domestic ones from five parishes of Grenada, were sampled during a 4-month period of January to April 2013 and examined by enrichment and selective culture for the presence of Salmonella spp. Fifty-five per cent of the animals were positive, and eight serovars of Salmonella were isolated. The most common serovar was Rubislaw (58.8%), a serovar found recently in many cane toads in Grenada, followed by Oranienburg (14.7%), a serovar that has been causing serious human disease outbreaks in Japan. Serovar IV:48:g,z51 :- (formerly, S. Marina) highly invasive and known for serious infections in children in the United States, constituted 11.8% of the isolates, all of them being from domestic green iguanas. Salmonella Newport, a serovar recently found in a blue land crab in Grenada, comprised 11.8% of the isolates from the green iguanas. The remaining four less frequent serovars included S. Javiana and S. Glostrup. Antimicrobial susceptibility tests conducted by a disc diffusion method against amoxicillin-clavulanic acid, ampicillin, cefotaxime, ceftazidime, ciprofloxacin, enrofloxacin, gentamicin, nalidixic acid, streptomycin, tetracycline and trimethoprim-sulfamethoxazole showed that drug resistance is minimal, with intermediate susceptibility, mainly to streptomycin, tetracycline and cefotaxime. This is the first report of isolation and antimicrobial susceptibilities of various Salmonella serovars from wild and domestic green iguanas in Grenada, West Indies. PMID:24325463

  9. Enteropathogenicity and antimicrobial susceptibility of new Escherichia spp.

    PubMed

    Chaudhury, A; Nath, G; Tikoo, A; Sanyal, S C

    1999-06-01

    To determine the mechanism of enteropathogenicity of the newly described Escherichia species, a total of 50 clinical isolates of Escherichia spp. from diarrhoeal stools were studied. Twelve isolates (24%) were found to be E. vulneris, 6 (12%) E. fergusonii, 2 (4%) E. hermannii, and the rest 30 (60%) were E. coli. Most isolates of the new species were resistant to ampicillin, tetracycline, and co-trimoxazole, but were susceptible to cephalosporins and aminoglycosides. The representative strains of all the new species produced significant fluid accumulation in the rat ileal loops both by live cells and their culture filtrates. E. vulneris, isolated from stools, showed maximum fluid accumulation. Thus, it can be inferred that these species are diarrhoeagenic, but their roles on extra-intestinal infections remain to be determined. PMID:10897892

  10. Differential antimicrobial susceptibility between human and chicken isolates of vancomycin-resistant and sensitive Enterococcus faecium.

    PubMed

    Chen, Han Yuan; Hill, Robert L R; Kirk, Monica; Casewell, Mark W; Beighton, David

    2002-01-01

    To compare the differential antimicrobial susceptibilities of Enterococcus faecium from humans and whole chicken carcasses, MICs of 12 antimicrobial agents were determined for 54 clinical-isolates (31 vancomycin-resistant [VREF]) and 60 chicken-isolates (29 VREF). Chicken VREF were slightly but consistently more resistant to vancomycin, teicoplanin and avoparcin, compared with human VREF (P<0.01). MICs of LY333328 were susceptible to chloramphenicol than human VREF (P<0.001). PMID:11814766

  11. A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

    PubMed

    Koeth, Laura M; DiFranco-Fisher, Jeanna M; McCurdy, Sandra

    2015-01-01

    Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity. PMID:26381422

  12. Susceptibility testing of Mycobacterium abscessus by isothermal microcalorimetry.

    PubMed

    Boillat-Blanco, Noémie; Furustrand Tafin, Ulrika; Jaton, Katia; Trampuz, Andrej

    2015-10-01

    We evaluated a new method for susceptibility testing of a rapidly growing mycobacterium using real-time measurement of heat (microcalorimetry). MICs of 2 clinical Mycobacterium abscessus isolates were determined by microbroth dilution and E-test. For microcalorimetry, Middlebrook-7H10 agar+10% oleic acid-albumin-dextrose-catalase, containing amikacin, clarithromycin, linezolid, and ciprofloxacin was inoculated with ~10(5)CFU/mL. Heat production was measured at 37°C for 72h. Minimal heat inhibition concentration (MHIC) was defined as the lowest antibiotic concentration inhibiting growth-related heat production. Growth of M. abscessus was detected after a median of 16.5h (range, 8.5-26.9h). Heat detection was proportionally delayed with increasing concentration of antibiotics. MHICs for the tested strains were 16 to >16mg/L for amikacin, >8mg/L for clarithromycin, 4 to >16mg/L for ciprofloxacin, 24 to >32mg/L for linezolid. MHICs were in agreement within two 2-fold dilutions with conventional MICs. Microcalorimetry may accelerate antimicrobial susceptibility testing in mycobacteria and provide additional real-time information on the drug effect. PMID:26210204

  13. Microbial Etiology and Antimicrobial Susceptibility of Bactria Implicated in Urinary Tract Infection in Tehran, Iran

    PubMed Central

    Nozarian, Zohreh; Abdollahi, Alireza

    2015-01-01

    Background and Objectives: Urinary tract infections (UTI) are one of the most common infectious diseases with different microbial agent and antimicrobial resistant pattern in hospitalized patients and outpatients. In order to assess the adequacy of therapy, knowledge of prevalence and resistance pattern of the bacteria is necessary. The main aim of this study was to evaluate the prevalence and the antimicrobial resistance pattern of main bacterial responsible for UTI in order to establish an appropriate empirical therapy. Methods: All urine samples were referred to Imam Hospital Laboratory, Tehran, Iran during 2011-2012, urine culture isolated and bacteria were identified and the profile of antibiotic susceptibility was characterized. Result: From 1851 urine cultures, UTI was more frequent in woman (68%) E. coli was as usual the most common pathogen implicated in UTI. Most susceptibility was to imipenem (98.9%). nitroforantoin (96%) and amikacin (94.1%) and increased resistance to penicillin (66.6%), nalidixic acid (62.1%) ampicilin (60.1%) and cotrimoxazole 54.3%. Discussion: The most common isolated pathogen was E. coli . According to antibiogram susceptibility, the recommended antimicrobial drugs are nitroforantoin and imipenem. nalidixic acid and cotrimoxazole are not recommended because drug resistance is high. PMID:26516326

  14. Staphylococcus aureus isolated from pork and chicken carcasses in Taiwan: prevalence and antimicrobial susceptibility.

    PubMed

    Lin, Jyhshiun; Yeh, Kuang-Sheng; Liu, Hsueh-Tao; Lin, Jiunn-Horng

    2009-03-01

    Staphylococcus aureus is a cause of many diseases in both humans and animals. This pathogen is also a major target in the screening of slaughterhouse carcasses to monitor hygienic conditions during slaughter. During 2004 to 2006, S. aureus was recovered from 8.8% (38 of 430), 11.3% (77 of 680), and 4.3% (13 of 300) of pork carcass samples, respectively, collected at 53 slaughterhouses in Taiwan. During 2003 to 2005, it was recovered from 0.3% (1 of 305), 0.4% (1 of 260), and 7.8% (31 of 395) of rinse fluids from chicken carcasses, respectively, collected at 17 meat processing plants. The minimum dilution method was used to determine antimicrobial susceptibility (MICs) of these strains (n = 103) as well as those collected from pork and chicken carcasses (n = 104) in a previous study beginning in 2000. All 207 strains were sensitive to nitrofurantoin and vancomycin. Over 50% were resistant to clindamycin (MIC that inhibited 90% of strains [MIC90] = 32 microg/ml) and tetracycline (MIC90 = 64 microg/ml). The percentages resistant to methicillin (oxacillin), chloramphenicol, erythromycin, and tylosin were 19.4% (40 of 207), 18.8% (39 of 207), 23.2% (48 of 207), and 20.8% (43 of 207) with MIC90s of 8, 64, > or = 64, and > or = 128 microg/ml, respectively. The methicillin-resistant S. aureus (MRSA) strains exhibited resistance to more antibiotics than did the methicillin-susceptible strains, and 87.5% (35 of 40) of the MRSA strains carried the mecA gene sequence. Since MRSA infections have become a public health concern in both communities and hospitals, testing for the presence of MRSA in animal carcasses during slaughtering operations is warranted. PMID:19343951

  15. Prevalence and Antimicrobial Susceptibility of Campylobacter spp. in Oklahoma Conventional and Organic Retail Poultry

    PubMed Central

    Noormohamed, Aneesa; Fakhr, Mohamed K

    2014-01-01

    Campylobacter is one of the most important foodborne pathogens that cause bacterial gastroenteritis.This study was conducted to investigate the prevalence and antimicrobial resistance of Campylobacter in conventional and organic retail poultry samples purchased from grocery stores in Tulsa, Oklahoma.One hundred and fifty six chilled retail chicken samples (85 conventional and 71 organic) and 65 chilled retail conventional turkey samples were collected in this study. The prevalence of Campylobacter in the conventional chicken samples 32/85 (38%) was higher than in the organic ones 21/71 (30%). The prevalence of Campylobacter in the conventional turkey samples was 11/65 (17%). Of the 53 positive chicken samples, 42 were C. jejuni, 8 were C. coli and three isolates were contaminated with both species. Of the 11 positive turkey samples, 8 contained C. jejuni and 3 harbored C. coli isolates. The antimicrobial susceptibility of one hundred and forty nine recovered Campylobacter isolates (130 chickens and 19 turkeys) towards sixteen antimicrobials was determined. The majority of the recovered turkey isolates (13/19) showed resistance to more than 7 antimicrobials while most of the recovered chicken ones (82/130) were resistant to 5 to 7 antimicrobials. Multidrug resistance was not limited to isolates from conventional sources but was also available in isolates of an organic background and was generally lower in C. jejuni isolates when compared to the C. coli ones. PMID:25408778

  16. Antimicrobial susceptibilities and bacteriological characteristics of bovine Pseudomonas aeruginosa and Serratia marcescens isolates from mastitis.

    PubMed

    Ohnishi, Mamoru; Sawada, Takuo; Hirose, Kazuhiko; Sato, Reiichiro; Hayashimoto, Mizuki; Hata, Eiji; Yonezawa, Chizuko; Kato, Hajime

    2011-12-29

    The presence of metallo-β-lactamase (MBL)-producing and multidrug-resistant Pseudomonas aeruginosa (MDRP) strains among bovine isolates of Gram-negative bacilli, and O-serotypes of bovine Serratia marcescens and P. aeruginosa isolates have been reported rarely. The aims of this study were to (1) elucidate antimicrobial susceptibilities and O-serotypes of P. aeruginosa and S. marcescens isolates from bovine mastitis and the presence of MBL-producers and MDRP strains among them and (2) evaluate their relationships to human isolates. We investigated the MICs of 24 antimicrobials and O-serotypes for 116 P. aeruginosa and 55 S. marcescens isolates in Japan, primarily in 2006. A total of 171 isolates exhibited high antimicrobial susceptibilities with the exception of a partial drug. P. aeruginosa isolates exhibited high susceptibilities of ≥ 95.7% to ciprofloxacin, imipenem, meropenem, piperacillin, ceftazidime, cefepime, cefoperazone/sulbactam, amikacin, tobramycin, and gentamicin; however, they exhibited a susceptibility of only 69.8% to aztreonam. They exhibited substantial resistances to ceftriaxone, enrofloxacin, cefotaxime, and moxalactam. S. marcescens isolates exhibited high susceptibilities of ≥ 90.9% to kanamycin, ceftiofur, sulfamethoxazole-trimethoprim, and the 15 aforementioned drugs, but exhibited resistance to minocycline. Neither MBL-producers nor MDRP strains were detected among the 171 strains. The dominant serotypes of P. aeruginosa isolates were OG, OA, OB, OI, OF, OE, and OK; those of S. marcescens isolates were O6 and O5. Every S. marcescens isolate was pigmented. These findings suggest that bovine P. aeruginosa and S. marcescens isolates differ from human isolates from both antibiogram and phenotypic perspectives, and could help to evaluate differences in bacteriological characteristics between bovine and human isolates. PMID:21783330

  17. In vitro antimicrobial susceptibility of Helcococcus kunzii and molecular analysis of macrolide and tetracycline resistance.

    PubMed

    Vergne, A; Guérin, F; Lienhard, R; Le Coustumier, A; Daurel, C; Isnard, C; Marty, N; Poyart, C; Cattoir, V

    2015-10-01

    Thanks to the recent advent of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) technology, Helcococcus kunzii is now easily identifiable and considered as an opportunistic pathogen. However, data about antimicrobial susceptibilities remain very limited. The aim of the study was, then, to assess its in vitro susceptibility to 18 antimicrobial agents and to investigate the genetic basis of macrolide and tetracycline resistance. Thirty-nine human clinical isolates of H. kunzii collected from 2008 to 2013 were studied, as well as the type strain ATCC 51366(T). Minimum inhibitory concentrations (MICs) of penicillin G, amoxicillin, cefotaxime, imipenem, gentamicin, erythromycin, clindamycin, quinupristin-dalfopristin, ciprofloxacin, levofloxacin, tetracycline, tigecycline, vancomycin, teicoplanin, linezolid, daptomycin, cotrimoxazole and rifampin were determined by the microdilution method. Screening for macrolide [erm(A) including erm(TR), erm(B), erm(C), erm(F), erm(T), erm(X), msr(A) and mef(A)] and tetracycline [tet(L), tet(M) and tet(O)] resistance genes was performed, as well as the detection of mutations in 23S rRNA. Except for one strain resistant to cefotaxime, all strains were categorised as susceptible to β-lactams, glycopeptides, linezolid, daptomycin and tigecycline. Whereas ciprofloxacin and gentamicin exhibited limited activity, 95% of strains were categorised as susceptible to levofloxacin. Concerning erythromycin, a bimodal distribution was observed, with 29 'wild-type' strains (MICs from 0.25 to 2 mg/L) and 11 'resistant' strains (MICs ≥ 256 mg/L), including ten harbouring erm(TR). Two isolates exhibited acquired tetracycline resistance (MICs of 16 mg/L) by the production of tet(M). This large study on the in vitro antimicrobial susceptibility of H. kunzii suggests that β-lactams (especially penicillins) should be preferred for the treatment. PMID:26194694

  18. Antimicrobial susceptibility of pediatric uropathogens in Thrace, Greece.

    PubMed

    Mantadakis, Elpis; Tsalkidis, Aggelos; Panopoulou, Maria; Pagkalis, Spyridon; Tripsianis, Gregory; Falagas, Mathew E; Falagas, Mathew; Kartali-Ktenidou, Sophia; Chatzimichael, Athanassios

    2011-06-01

    The aim of this study was to investigate the bacterial pathogens involved in pediatric urinary tract infections (UTIs) in a tertiary general hospital located in the Thrace province of Northern Greece over a 69-month period (1/2003 to 9/2008), and their antibiotic susceptibility patterns. A total of 622 episodes of UTIs in 508 children were identified. Median age of all children was 16 months (range 1 month to 14 years). Boys were significantly younger than girls (9 months vs. 24 months). Escherichia coli was the most common uropathogen and responsible for 69.1% of UTIs. Approximately half of E. coli isolates were resistant to ampicillin and 20.5% to trimethoprim/sulfamethoxazole (TMP/SMX). E. coli resistance to second-generation and third-generation cephalosporins was <4%, to aminoglycosides <8%, and to nitrofurantoin 4.4%. Pediatric E. coli urine isolates were significantly more resistant to ampicillin and ticarcillin and more sensitive to quinolones compared to adult E. coli uropathogens identified in the same hospital. E. coli resistance to ampicillin and amoxicillin/clavulanic acid was significantly higher in boys 12-23 months-old compared to girls of the same age. In conclusion, nitrofurantoin is a very good choice for chemoprophylaxis. Amoxicillin/clavulanic acid, second-generation cephalosporins, and TMP/SMX are appropriate choices for oral empirical treatment of UTIs. Parenteral aminoglycosides and second and third-generation cephalosporins are excellent treatment choices for inpatient therapy. Finally, sex and age are additional factors that should be taken into account when choosing empirical therapy for children with UTIs. PMID:20524067

  19. E test as susceptibility test and epidemiologic tool for evaluation of Neisseria meningitidis isolates.

    PubMed Central

    Hughes, J H; Biedenbach, D J; Erwin, M E; Jones, R N

    1993-01-01

    The E test (AB Biodisk, Solna, Sweden), a new approach developed to test antimicrobial susceptibility, was compared with the agar dilution method for seven-drug antibiogram analysis of Neisseria meningitidis isolates. The overall E-test quantitative accuracy (+/- 1 log2 dilution) was 93% compared with that of agar dilution testing. The E test was then used to perform the susceptibility tests on a 10-year sample of 102 N. meningitidis isolates, including 5 from a recent epidemic outbreak in the University of Iowa (Iowa City) community. The E test proved to be an efficient methodology for identifying common source clusters of meningococcal disease having resistance to rifampin or sulfonamides. Moreover, the data demonstrated a recent increase in penicillin MICs (MIC for 90% of strains, 0.094 microgram/ml) and an escalation of high-level resistance to trimethoprimsulfamethoxazole (33%) and rifampin (14%). The E test should be considered a simple and accurate susceptibility method for the emerging need to test meningococci and other pathogenic neisserias. Chocolate Mueller-Hinton agar was observed to provide the best support of growth and E-test MIC results that correlated well with results of the reference agar dilution method previously used for neisserias. PMID:8308119

  20. Development of an intracanal mature Enterococcus faecalis biofilm and its susceptibility to some antimicrobial intracanal medications; an in vitro study

    PubMed Central

    Saber, Shehab El-Din Mohamed; El-Hady, Soha A.

    2012-01-01

    Objectives: To develop a mature biofilm of Enterococcus faecalis inside the root canal system and to test its susceptibility to some antimicrobial medications in vitro. Methods: Single rooted premolars were mechanically enlarged, sterilized, and then infected with a clinical isolate of E. faecalis. Biofilm formation and maturation was monitored using SEM. Biofilm bacteria were exposed to Amoxicillin+clavulanate, Ciprofloxacin, Clindamycin, Doxycycline, and calcium hydroxide as intracanal medications for 1 week. Finally bacterial samples were collected, and colony-forming units were enumerated. Results: SEM examination confirmed the formation of a mature biofilm at the end of the incubation period. All the chemotherapeutic agents used were significantly better than Calcium hydroxide in elimination of biofilm bacteria. The antimicrobial effect of Amoxicillin + clavulanate, Ciprofloxacin and Clindamycin was significantly better than Doxycycline (P=.05). However the difference in the antimicrobial effectiveness among them was statistically non-significant (P=.05). Conclusions: The method used for bacterial biofilm development and maturation is reliable and can be used to assess the anti bacterial potential of endodontic materials. Also, the local application of antibacterial agents can be beneficial in resistant cases of apical periodontitis but only after careful culture and sensitivity testing to choose the appropriate agent for the existing flora. PMID:22229006

  1. Disk Agar Diffusion Susceptibility Testing of Yeasts

    PubMed Central

    Saubolle, Michael A.; Hoeprich, Paul D.

    1978-01-01

    A disk agar diffusion method was developed for testing the susceptibility of rapidly growing yeasts in vitro. A totally defined, completely synthetic agar culture medium (synthetic amino acid medium, fungal) and clinical isolates of Candida spp. and Torulopsis glabrata were used. Turbidimetric adjustment of cell suspensions resulted in standard, reproducible inocula, which gave sharp, clear zones of inhibition when applied by an agar overlay method. Optimal disk loads were determined for amphotericin B, amphotericin B methyl ester, 5-fluorocytosine, clotrimazole, and miconazole. Disk potencies were stable over a 2-month period when stored in a vacuum desiccator at −30°C. Using an error ratebounded classification, the zones of inhibition were correlated with both broth dilution and agar dilution minimum inhibitory concentrations (MICs). With amphotericin B and amphotericin B methyl ester, all isolates were susceptible, yielding zone diameters which clustered within 5 mm. Overall correlations between zone diameters and broth dilution MICs with 5-fluorocytosine, miconazole, and clotrimazole were 97, 96, and 82% (excluding T. glabrata), respectively; correlations of zone diameters with agar dilution MICs were 96, 92, and 88%, respectively. Disk diffusion susceptibility testing of yeasts appears to be generally applicable. However, when results are equivocal, quantitative test methods should be used. PMID:568910

  2. Susceptibility to antimicrobial agents among bovine mastitis pathogens isolated from North American dairy cattle, 2002-2010.

    PubMed

    Lindeman, Cynthia J; Portis, Ellen; Johansen, Lacie; Mullins, Lisa M; Stoltman, Gillian A

    2013-09-01

    Approximately 8,000 isolates of Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Staphylococcus aureus, and Escherichia coli, isolated by 25 veterinary laboratories across North America between 2002 and 2010, were tested for in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs. The minimal inhibitory concentrations (MICs) of the beta-lactam drugs remained low against most of the Gram-positive strains tested, and no substantial changes in the MIC distributions were seen over time. Of the beta-lactam antimicrobial agents tested, only ceftiofur showed good in vitro activity against E. coli. The MICs of the macrolides and lincosamides also remained low against Gram-positive mastitis pathogens. While the MIC values given by 50% of isolates (MIC50) for erythromycin and pirlimycin and the streptococci were all low (≤0.5 µg/ml), the MIC values given by 90% of isolates (MIC90) were higher and more variable, but with no apparent increase over time. Staphylococcus aureus showed little change in erythromycin susceptibility over time, but there may be a small, numerical increase in pirlimycin MIC50 and MIC90 values. Overall, the results suggest that mastitis pathogens in the United States and Canada have not shown any substantial changes in the in vitro susceptibility to beta-lactam, macrolide, and lincosamide drugs tested over the 9 years of the study. PMID:23907894

  3. Bacteriological Profile and Antimicrobial Susceptibility Pattern of Blood Culture Isolates among Septicemia Suspected Children in Selected Hospitals Addis Ababa, Ethiopia

    PubMed Central

    Negussie, Adugna; Mulugeta, Gebru; Bedru, Ahmed; Ali, Ibrahim; Shimeles, Damte; Lema, Tsehaynesh; Aseffa, Abraham

    2015-01-01

    Background Blood stream infections are major cause of morbidity and mortality in children in developing countries. The emerging of causative agents and resistance to various antimicrobial agents are increased from time to time. The main aim of this study was to determine the bacterial agents and antimicrobial susceptibility patterns among children suspected of having septicemia. Methods A cross sectional study involved about 201 pediatric patients (≤ 12 years) was conducted from October 2011 to February 2012 at pediatric units of TikurAnbessa Specialized Hospital and Yekatit 12 Hospital. Standard procedure was followed for blood sample collection, isolate identifications and antimicrobial susceptibility testing. Results Among 201 study subjects 110 (54.7%) were males. Majority 147 (73.1%) of them were neonates (≤ 28 days). The mean length of hospital stay before sampling was 4.29 days. Out of the 201 tested blood samples, blood cultures were positive in 56 (27.9%).Gram negative and Gram positive bacteria constituted 29(51.8%) and 26(46.4%), respectively. The most frequent pathogen found was Staphylococcus aureus 13 (23.2%), followed by Serratia marcescens 12(21.4%), CoNS 11(19.6%), klebsiella spp 9(16%) and Salmonella spp 3(5.4%). Majority of bacterial isolates showed high resistance to Ampicillin, Penicillin, Co-trimoxazole, Gentamicin and Tetracycline which commonly used in the study area. Conclusion Majority of the isolates were multidrug resistant. These higher percentages of multi-drug resistant emerged isolates urge us to take infection prevention measures and to conduct other large studies for appropriate empiric antibiotic choice. PMID:26997847

  4. Population Genetics and Antimicrobial Susceptibility of Canine Campylobacter Isolates Collected before and after a Raw Feeding Experiment

    PubMed Central

    Roine, Johanna; Hänninen, Marja-Liisa; Hielm-Björkman, Anna; Kivistö, Rauni

    2015-01-01

    In recent years, increasing numbers of consumers have become interested in feeding raw food for their pet dogs as opposed to commercial dry food, in the belief of health advantages. However, raw meat and internal organs, possibly contaminated by pathogens such as Campylobacter spp., may pose a risk of transmission of zoonoses to the pet owners. Campylobacter jejuni is the leading cause of bacterial gastroenteritis in humans but C. upsaliensis has also been associated with human disease. In this study we investigated the effect of different feeding strategies on the prevalence of Campylobacter spp. in Finnish dogs. We further characterized the isolates using multilocus sequence typing (MLST), whole-genome (wg) MLST and antimicrobial susceptibility testing. Dogs were sampled before and after a feeding period consisting of commercial raw feed or dry pellet feed. Altogether 56% (20/36) of the dogs yielded at least one Campylobacter-positive fecal sample. C. upsaliensis was the major species detected from 39% of the dogs before and 30% after the feeding period. Two C. jejuni isolates were recovered, both from raw-fed dogs after the dietary regimen. The isolates represented the same genotype (ST-1326), suggesting a common infection source. However, no statistically significant correlation was found between the feeding strategies and Campylobacter spp. carriage. The global genealogy of MLST types of dog and human C. upsaliensis isolates revealed weakly clonal population structure as most STs were widely dispersed. Major antimicrobial resistance among C. upsaliensis isolates was against streptomycin (STR MIC > 4mg/l). Apart from that, all isolates were highly susceptible against the antimicrobials tested. Mutations were found in the genes rpsL or rpsL and rsmG in streptomycin resistant isolates. In conclusion, increasing trend to feed dogs with raw meat warrants more studies to evaluate the risk associated with raw feeding of pets in transmission of zoonoses to humans

  5. Prevalence, Molecular Characterization, and Antimicrobial Susceptibility of Methicillin-Resistant Staphylococcus aureus Isolated from Milk and Dairy Products.

    PubMed

    Al-Ashmawy, Maha Abdou; Sallam, Khalid Ibrahim; Abd-Elghany, Samir Mohammed; Elhadidy, Mohamed; Tamura, Tomohiro

    2016-03-01

    The present work was undertaken to study the prevalence, molecular characterization, virulence factors, and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) in raw milk and dairy products in Mansoura City, Egypt. MRSA was detected in 53% (106/200) among all milk and dairy products with prevalence rates of 75%, 65%, 40%, 50%, and 35% in raw milk, Damietta cheese, Kareish cheese, ice cream, and yogurt samples, respectively. The mean S. aureus counts were 3.49, 3.71, 2.93, 3.40, and 3.23 log10 colony-forming units (CFU)/g among tested raw milk, Damietta cheese, Kareish cheese, ice cream and yogurt, respectively, with an overall count of 3.41 log10 CFU/g. Interestingly, all recovered S. aureus isolates were genetically verified as MRSA strains by molecular detection of the mecA gene. Furthermore, genes encoding α-hemolysin (hla) and staphylococcal enterotoxins (sea, seb, sec) were detected in all isolates. The antimicrobial susceptibility pattern of recovered MRSA isolates against 13 tested antimicrobials revealed that the least effective drugs were penicillin G, cloxacillin, tetracycline, and amoxicillin with bacterial resistance percentages of 87.9%, 75.9%, 65.2%, and 55.6%, respectively. These findings suggested that milk and dairy products represent a potential infection risk threat of multidrug-resistant and toxigenic S. aureus in Egypt due to neglected hygienic practices during production, retail, or storage stages. These findings highlighted the crucial importance of applying more restrictive hygienic measures in dairy production in Egypt for food safety. PMID:26836943

  6. Antimicrobial susceptibility of Staphylococcus aureus and characterization of methicillin-resistant Staphylococcus aureus isolated from bovine mastitis in Korea.

    PubMed

    Nam, Hyang-Mi; Lee, Ae-Li; Jung, Suk-Chan; Kim, Mal-Nam; Jang, Geum-Chan; Wee, Sung-Hwan; Lim, Suk-Kyung

    2011-02-01

    A total of 402 Staphylococcus aureus isolates from bovine mastitis milk collected during 2003-2009 in Korea were tested for susceptibility to 20 antimicrobial agents. All S. aureus isolates were susceptible to 11 of 20 antimicrobials tested; no resistance was observed against pirlimycin, telithromycin, novobiocin, penicillin/novobiocin, quinupristin/dalfopristin, clindamycin, rifampin, ciprofloxacin, trimethprim/sulfamethoxazol, vancomycin, and linezolid. Over 66% of the S. aureus isolates were resistant to penicillin. Resistance was also seen for gentamicin (11.9%), erythromycin (7.7%), methicillin (oxacillin and cefoxitin, 6.2%), and tetracycline (4.2%). No noticeable change was observed in penicillin, gentamicin, and erythromycin resistance over the 7-year period. Tetracycline resistance appeared to decrease consistently, whereas methicillin resistance was observed from 2005. About 2.7% (11/402) were resistant to three or more antimicrobials. Genotyping of the 17 methicillin-resistant S. aureus (MRSA) isolated from each cow revealed two staphylococcal cassette chromosome mec (SCCmec) types (IV and IVa), three spa types (t286, t324, and untypable), and two sequence types (ST1 and ST72). Eleven of 17 (64.7%) MRSA strains belonged to SCCmec IVa-t324-ST72. The rest of strains belonged to SCCmec IVa-t286-ST1 (n = 3) and SCCmec IV-untypable-ST72 (n = 3). None of the MRSA carried the Panton-Valentine leukocidin gene. These characteristics are the same as those found in community-acquired (CA) MRSA strains prevalent in humans in Korea. Three pulsed-field gel electrophoresis types (A-C) were observed among the 17 MRSA strains examined, and 14 strains belonged to the same pulsed-field gel electrophoresis pattern regardless of their geographical origin and year of isolation. The results of this study provide evidence of CA-MRSA infection in dairy cattle for the first time in Korea. PMID:21034263

  7. Population Genetics and Antimicrobial Susceptibility of Canine Campylobacter Isolates Collected before and after a Raw Feeding Experiment.

    PubMed

    Olkkola, Satu; Kovanen, Sara; Roine, Johanna; Hänninen, Marja-Liisa; Hielm-Björkman, Anna; Kivistö, Rauni

    2015-01-01

    In recent years, increasing numbers of consumers have become interested in feeding raw food for their pet dogs as opposed to commercial dry food, in the belief of health advantages. However, raw meat and internal organs, possibly contaminated by pathogens such as Campylobacter spp., may pose a risk of transmission of zoonoses to the pet owners. Campylobacter jejuni is the leading cause of bacterial gastroenteritis in humans but C. upsaliensis has also been associated with human disease. In this study we investigated the effect of different feeding strategies on the prevalence of Campylobacter spp. in Finnish dogs. We further characterized the isolates using multilocus sequence typing (MLST), whole-genome (wg) MLST and antimicrobial susceptibility testing. Dogs were sampled before and after a feeding period consisting of commercial raw feed or dry pellet feed. Altogether 56% (20/36) of the dogs yielded at least one Campylobacter-positive fecal sample. C. upsaliensis was the major species detected from 39% of the dogs before and 30% after the feeding period. Two C. jejuni isolates were recovered, both from raw-fed dogs after the dietary regimen. The isolates represented the same genotype (ST-1326), suggesting a common infection source. However, no statistically significant correlation was found between the feeding strategies and Campylobacter spp. carriage. The global genealogy of MLST types of dog and human C. upsaliensis isolates revealed weakly clonal population structure as most STs were widely dispersed. Major antimicrobial resistance among C. upsaliensis isolates was against streptomycin (STR MIC > 4 mg/l). Apart from that, all isolates were highly susceptible against the antimicrobials tested. Mutations were found in the genes rpsL or rpsL and rsmG in streptomycin resistant isolates. In conclusion, increasing trend to feed dogs with raw meat warrants more studies to evaluate the risk associated with raw feeding of pets in transmission of zoonoses to humans

  8. Antimicrobial susceptibility of Staphylococcus pseudintermedius colonizing healthy dogs in Saskatoon, Canada

    PubMed Central

    Priyantha, Roshan; Gaunt, Mathew C.; Rubin, Joseph E.

    2016-01-01

    This study reports antimicrobial susceptibility of Staphylococcus pseudintermedius carried by healthy dogs in Saskatoon, and describes changes in antimicrobial resistance since a 2008 study. One hundred healthy dogs presenting to the wellness service at the Western College of Veterinary Medicine were screened for S. pseudintermedius by culturing rectal and pharyngeal swabs. Staphylococcus pseudintermedius was identified biochemically and antimicrobial minimum inhibitory concentrations were determined by broth microdilution. Methicillin resistance was confirmed by polymerase chain reaction (PCR) and sequencing of the mecA gene. Of 221 S. pseudintermedius isolates from 78 dogs, 7 were methicillin resistant. No resistance to the fluoroquinolones, nitrofurantoin, tigecycline, vancomycin, quinupristin-dalfopristin, linezolid, or daptomycin was identified. Of the 78 positive dogs, isolates resistant to penicillin were found in 78%, to ampicillin in 61% and to tetracycline in 26%; resistance to oxacillin, erythromycin, clindamycin, trimethoprim + sulfamethoxazole, chloramphenicol, and gentamicin was found in < 10% of dogs. Compared to the 2008 study, the frequency of resistance to all drugs increased, and the frequency of colonization with pan-susceptible isolates decreased from 46% to 30%. PMID:26740701

  9. Antimicrobial Susceptibility of Enterococcal Species Isolated from Antibiotic-Treated Dogs and Cats

    PubMed Central

    KATAOKA, Yasushi; UMINO, Yurie; OCHI, Hiroki; HARADA, Kazuki; SAWADA, Takuo

    2014-01-01

    ABSTRACT In this study, we examined the antimicrobial susceptibility of the enterococci isolated from dogs and cats in Japan during 2011–2012. Fecal samples were collected from 84 dogs and 16 cats that underwent antibiotic treatment. Enterococci were detected in 70 of 84 dogs (83.3%) and 7 of 16 cats (43.8%). The most prevalent Enterococcus species was Enterococcus faecalis (64.9%); Enterococccus faecium and Enterococcus durans were also isolated from 14 of 77 (18.2%) and 5 of 77 (6.5%) of these animals, respectively. The most active resistance was observed for erythromycin (44.2%) and oxytetracycline (44.2%), and there was considerable resistance to lincomycin (41.6%), gentamicin (31.2%) and kanamycin (31.2%). Compared with the results of a similar study conducted in 2006 and 2007, enterococci susceptibility to enrofloxacin and ampicillin had significantly increased. Enterococcus gallinarum harboring vanC1 and Enterococcus casseliflavus harboring vanC2/3 were isolated from 4 of 77 enterococcal isolates. However, no enterococcal isolates were resistant to vancomycin. Multidrug resistance was found for as few as two and as many as nine antimicrobials regardless of the class. These results demonstrate that dogs and cats treated with antibiotics are commonly colonized with antimicrobial-resistant enterococci. PMID:24976587

  10. Antimicrobial susceptibility of Staphylococcus pseudintermedius colonizing healthy dogs in Saskatoon, Canada.

    PubMed

    Priyantha, Roshan; Gaunt, Mathew C; Rubin, Joseph E

    2016-01-01

    This study reports antimicrobial susceptibility of Staphylococcus pseudintermedius carried by healthy dogs in Saskatoon, and describes changes in antimicrobial resistance since a 2008 study. One hundred healthy dogs presenting to the wellness service at the Western College of Veterinary Medicine were screened for S. pseudintermedius by culturing rectal and pharyngeal swabs. Staphylococcus pseudintermedius was identified biochemically and antimicrobial minimum inhibitory concentrations were determined by broth microdilution. Methicillin resistance was confirmed by polymerase chain reaction (PCR) and sequencing of the mecA gene. Of 221 S. pseudintermedius isolates from 78 dogs, 7 were methicillin resistant. No resistance to the fluoroquinolones, nitrofurantoin, tigecycline, vancomycin, quinupristin-dalfopristin, linezolid, or daptomycin was identified. Of the 78 positive dogs, isolates resistant to penicillin were found in 78%, to ampicillin in 61% and to tetracycline in 26%; resistance to oxacillin, erythromycin, clindamycin, trimethoprim + sulfamethoxazole, chloramphenicol, and gentamicin was found in < 10% of dogs. Compared to the 2008 study, the frequency of resistance to all drugs increased, and the frequency of colonization with pan-susceptible isolates decreased from 46% to 30%. PMID:26740701

  11. Frequency of Susceptibility Testing for Patients with Persistent Methicillin-Resistant Staphylococcus aureus Bacteremia

    PubMed Central

    Giltner, Carmen L.; Kelesidis, Theodoros; Hindler, Janet A.; Bobenchik, April M.

    2014-01-01

    Currently, no standards exist for determining the optimal frequency of repeat antimicrobial susceptibility testing (AST) when an organism is recurrently isolated from the same specimen source. Although testing every 2 to 5 days is thought sufficient, we present three cases of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia where current laboratory protocol for repeating AST every 5 days was inadequate to identify resistant organisms. PMID:24153125

  12. Antimicrobial susceptibility of pathogenic Escherichia coli isolated from sick cattle and pigs in Japan.

    PubMed

    Harada, Kazuki; Asai, Tetsuo; Kojima, Akemi; Oda, Chitose; Ishihara, Kanako; Takahashi, Toshio

    2005-10-01

    We examined the 12 antimicrobial susceptibilities of 175 E. coli isolates from sick cattle and pigs by an agar dilution method. Resistance was found in 78.3% of isolates for oxytetracycline, 70.3% of isolates for dihydrostreptomycin, and 49.1% of isolates for ampicillin. When compared with healthy animals reported by Kijima-Tanaka et al., resistance rates for 11 antimicrobial agents were higher in sick cattle than in healthy cattle, and resistance rates for all antimicrobial agents were higher in sick pigs than in healthy pigs. Comparing cattle and pigs, resistance rates to colistin was higher in porcine isolates than in bovine isolates, but was lower in porcine isolates than in bovine isolates for cefazolin. With regard to the association of virulence factors, higher resistance rates to colistin and enrofloxacin were observed in STEC (61 strains) than in non-STEC (57 strains) among porcine isolates, while there were no significant differences in bovine isolates. In conclusion, these results can be considered helpful for adequate selection and prudent use of antimicrobial agents for several types of colibacillosis. PMID:16276055

  13. NORMAL VAGINAL BACTERIAL FLORA OF GIANT PANDAS (AILUROPODA MELANOLEUCA) AND THE ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF THE ISOLATES.

    PubMed

    Yang, Xin; Yang, Jiang; Wang, Hongning; Li, Caiwu; He, Yongguo; Jin, SenYan; Zhang, Hemin; Li, Desheng; Wang, Pengyan; Xu, Yuesong; Xu, Changwen; Fan, Chengyun; Xu, Lulai; Huang, Shan; Qu, Chunmao; Li, Guo

    2016-06-01

    To study the typical vaginal bacterial flora of giant pandas (Ailuropoda melanoleuca), we took vaginal swabs for the sake of bacterial isolation, from 24 healthy female giant pandas. A total of 203 isolates were identified, representing a total of 17 bacterial species. The most common bacteria isolated were Lactobacillus spp. (54.2%, 13/24), followed by Staphylococcus epidermidis (41.7%, 10/24) and Escherichia coli (33.3%, 8/24). Some opportunistic pathogenic bacteria, such as Peptostreptococcus spp., Klebsiella pneumoniae , and Proteus mirabilis , were also isolated but showed no pathology. Antimicrobial susceptibility testing of aerobic bacterial isolates was performed with the disk diffusion method. Of the 152 isolates, resistance was most frequently observed with chloramphenicol (17.8%), followed by tetracycline (14.5%), ciprofloxacin (12.5%), streptomycin (11.8%), and florfenicol (11.8%), whereas 7.2% were multidrug resistant. This is the first report of the normal culturable vaginal bacterial flora of giant pandas and the antimicrobial susceptibility patterns of the isolates. PMID:27468049

  14. NORMAL VAGINAL BACTERIAL FLORA OF GIANT PANDAS (AILUROPODA MELANOLEUCA) AND THE ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF THE ISOLATES.

    PubMed

    Yang, Xin; Yang, Jiang; Wang, Hongning; Li, Caiwu; He, Yongguo; Jin, SenYan; Zhang, Hemin; Li, Desheng; Wang, Pengyan; Xu, Yuesong; Xu, Changwen; Fan, Chengyun; Xu, Lulai; Huang, Shan; Qu, Chunmao; Li, Guo

    2016-03-01

    In order to study the typical vaginal bacterial flora of giant pandas (Ailuropoda melanoleuca), we took vaginal swabs for the sake of bacterial isolation, from 24 healthy female giant pandas. A total of 203 isolates were identified, representing a total of 17 bacterial species. The most common bacteria isolated were Lactobacillus spp. (54.2%, 13 of 24), followed by Staphylococcus epidermidis (41.7%, 10 of 24) and Escherichia coli (33.3%, 8 of 24). Some opportunistic pathogenic bacteria, such as Peptostreptococcus spp., Klebsiella pneumoniae, and Proteus mirabilis, were also isolated but showed no pathology. Antimicrobial susceptibility testing of aerobic bacterial isolates was performed with disk diffusion method. Of the 152 isolates, resistance was most frequently observed with chloramphenicol (17.8%), followed by tetracycline (14.5%), ciprofloxacin (12.5%), streptomycin (11.8%), and florfenicol (11.8%), while 7.2% were multidrug resistant. This is the first report of the normal vaginal culturable bacterial flora of giant pandas, followed by the antimicrobial susceptibility patterns of the isolates. PMID:27010307

  15. Isolation and antimicrobial susceptibility of Streptococcus castoreus isolated from carcasses of European beavers (Castor fiber) in Germany.

    PubMed

    Schulze, Christoph; Kutzer, Peter; Winterhoff, Nora; Engelhardt, Andreas; Bilk, Sabine; Teubner, Jens

    2015-01-01

    Streptococcus (S.) castoreus was isolated from seven beavers (Castor fiber), which were found dead in the federal state of Brandenburg, Germany, and submitted to the Berlin-Brandenburg State laboratory for post mortem diagnostics. The isolates originated from various inflammatory processes where they were associated with other Gram negative and Gram positive aerobic and/or anaerobic bacteria (i. e. Actinobacillus sp., species of the Actinomycetaceae family, coliform bacteria, Fusobacterium sp., Prevotella sp.), but also from cloacal swabs. Testing their antimicrobial susceptibility, all S. castoreus isolates and the type strain S. castoreus (DSM 17536) were classified as being susceptible to penicillin G, ampicillin, amoxicillin-clavulanic acid, 1st generation cephalosporins, erythromycin, tetracycline, and chloramphenicole but intermediate to gentamicin. Considering both the polymicrobial flora isolated from the inflamed tissues and the fact that antimicrobials of a narrow spectrum (namely penicillins, 1st generation cephalosporins, macrolids and lincosamids) can be toxic to rodents, chloramphenicol might be a suitable drug for treatment of beavers suffering from S. castoreus (mixed)-bacterial infections. PMID:26591385

  16. Antimicrobial susceptibility of Neisseria gonorrhoeae in Zaire: high level plasmid-mediated tetracycline resistance in central Africa.

    PubMed Central

    Van Dyck, E; Rossau, R; Duhamel, M; Behets, F; Laga, M; Nzila, M; Bygdeman, S; Van Heuverswijn, H; Piot, P

    1992-01-01

    OBJECTIVE--To determine the in vitro antimicrobial susceptibility of gonococcal strains isolated in 1988 among female prostitutes in Kinshasa, Zaire and to characterise strains with high level tetracycline resistance. METHODS--Minimal inhibitory concentrations of 8 antimicrobials were measured by agar dilution technique. Plasmid-profiles and serovars were determined. RESULTS--Two hundred and thirteen strains of Neisseria gonorrhoeae were tested of which 59% were beta-lactamase producers and an additional 21% showed intermediate or chromosomal resistance to penicillin (MIC = 0.5-8 mg/l). Eleven percent of the strains were resistant to the combination sulfamethoxazole-trimethoprim (MIC greater than 8 mg/l) and 57% of the isolates showed decreased susceptibility to thiamphenicol (MIC = 1-4 mg/l). All strains were sensitive to spectinomycin, norfloxacin and ceftriaxone and moderately sensitive to kanamycin. Chromosomal resistance to tetracycline was observed in 45% of strains (MIC = 2-8 mg/l). Ten percent were highly resistant to tetracycline (TRNG, MIC = 16-128 mg/l) and were shown to carry a plasmid borne Tet M determinant; such strains were not found in Kinshasa in 1985. TRNG belonged to 4 different serovars, which were also the dominant serovars in non-TRNG. CONCLUSION--These findings illustrate the high frequency of multiresistant gonococci in Zaire and suggest that high level tetracycline resistant strains of N. gonorrhoeae have become endemic in Central Africa. Images PMID:1582653

  17. Species distribution and antimicrobial susceptibility of enterococci isolated from broilers infected experimentally with Eimeria spp and fed with diets containing different supplements

    PubMed Central

    Cassenego, A.P.V.; d’Azevedo, P.A.; Ribeiro, A.M.L.; Frazzon, J.; Van Der Sand, S.T.; Frazzon, A. P. G.

    2011-01-01

    Resistant bacteria in animal can be spread to environment and to humans. Poultry feed and infections caused by Eimeria spp. are important factors in determining the intestinal microbial communities. The aim of this study was to verify the prevalence of species and antimicrobial susceptibility of Enterococcus isolated from broilers fed with different supplements and infected experimentally with Eimeria spp. Broilers were divided in eight groups, fed with diets supplemented with a combination of antimicrobial, ionophore-coccidiostatics, probiotic, essential oil. At 14 days old all birds, except the control, received a solution containing oocysts of Eimeria spp. Samples of cloacal swabs from broilers were collected. A total of 240 Enterococcus sp. strains were isolated, confirmed genus by PCR, classified as species, tested for antimicrobial susceptibility and screened by PCR for the presence of tet(L), tet(M) and erm(B) genes. The overall distribution of species isolated from fecal samples was E. faecalis (40%), followed by E. casseliflavus/E. gallinarum (10.8%), E. mundtii (10.8%), E. faecium (10.8%), E. columbae (5.8%) and E. gallinarum (4.2%). Changes in the composition or frequency of Enterococcus species were observed in all dietary supplementation. Antimicrobial susceptibility tests showed resistance phenotypes a range of antibiotics, especially used in humans such as, streptomycin, penicillin, rifampicin and vancomycin. There was no correlation between different supplementation for broilers and antimicrobial resistance and the presence of tet(M), tet(L) and erm(B) genes. Dietary supplementation had effect on the Enterococcus sp. colonization, but did not have significant effect on the phenotype and genotype of antimicrobial resistance in enterococci. PMID:24031659

  18. Species distribution and antimicrobial susceptibility of enterococci isolated from broilers infected experimentally with Eimeria spp and fed with diets containing different supplements.

    PubMed

    Cassenego, A P V; d'Azevedo, P A; Ribeiro, A M L; Frazzon, J; Van Der Sand, S T; Frazzon, A P G

    2011-04-01

    Resistant bacteria in animal can be spread to environment and to humans. Poultry feed and infections caused by Eimeria spp. are important factors in determining the intestinal microbial communities. The aim of this study was to verify the prevalence of species and antimicrobial susceptibility of Enterococcus isolated from broilers fed with different supplements and infected experimentally with Eimeria spp. Broilers were divided in eight groups, fed with diets supplemented with a combination of antimicrobial, ionophore-coccidiostatics, probiotic, essential oil. At 14 days old all birds, except the control, received a solution containing oocysts of Eimeria spp. Samples of cloacal swabs from broilers were collected. A total of 240 Enterococcus sp. strains were isolated, confirmed genus by PCR, classified as species, tested for antimicrobial susceptibility and screened by PCR for the presence of tet(L), tet(M) and erm(B) genes. The overall distribution of species isolated from fecal samples was E. faecalis (40%), followed by E. casseliflavus/E. gallinarum (10.8%), E. mundtii (10.8%), E. faecium (10.8%), E. columbae (5.8%) and E. gallinarum (4.2%). Changes in the composition or frequency of Enterococcus species were observed in all dietary supplementation. Antimicrobial susceptibility tests showed resistance phenotypes a range of antibiotics, especially used in humans such as, streptomycin, penicillin, rifampicin and vancomycin. There was no correlation between different supplementation for broilers and antimicrobial resistance and the presence of tet(M), tet(L) and erm(B) genes. Dietary supplementation had effect on the Enterococcus sp. colonization, but did not have significant effect on the phenotype and genotype of antimicrobial resistance in enterococci. PMID:24031659

  19. Susceptibility testing of Danish isolates of Capnocytophaga and CDC group DF-2 bacteria.

    PubMed

    Bremmelgaard, A; Pers, C; Kristiansen, J E; Korner, B; Heltberg, O; Frederiksen, W

    1989-01-01

    Twelve Capnocytophaga and seven DF-2 strains were tested for their susceptibility to 14 antimicrobial agents using an agar dilution and an agar diffusion method. Twenty-three other antibiotics were evaluated using the diffusion test only. All strains were fully susceptible to penicillin, ampicillin, cefuroxime, cefotaxime, erythromycin, clindamycin, chloramphenicol, doxycycline, rifamycin and ofloxacin using both methods. Clindamycin, rifamycin and cefotaxime were most active. Using agar dilution some strains were susceptible to gentamicin, but agar diffusion showed total resistance. One Capnocytophaga strain was susceptible and another moderately susceptible to metronidazole, other strains were resistant. The agar diffusion test showed that both Capnocytophaga and DF-2 were resistant to most other aminoglycosides, to fosfomycin, polymyxin and trimethoprim. All strains of both taxa were fully susceptible to piperacillin, cefoxitin, imipenem and fusidic acid and showed different susceptibilities to the other agents. Susceptibility testing by means of agar diffusion using an enriched chocolate agar and 5% CO2 atmosphere could be used to test Capnocytophaga and DF-2 strains and gives sufficient accuracy for routine use, when revised inhibition zone breakpoints are employed. PMID:2914105

  20. Antimicrobial susceptibility of rapidly growing mycobacteria using the rapid colorimetric method.

    PubMed

    Ramis, I B; Cnockaert, M; von Groll, A; Nogueira, C L; Leão, S C; Andre, E; Simon, A; Palomino, J C; da Silva, P E A; Vandamme, P; Martin, A

    2015-07-01

    Drug susceptibility testing (DST) of rapidly growing mycobacteria (RGM) are recommended for guiding the antimicrobial therapy. We have evaluated the use of resazurin in Mueller-Hinton medium (MHR) for MIC determination of RGM and compared the results with those obtained with the reference standard broth microdilution in Mueller-Hinton (MH) and with the resazurin microtiter assay (REMA) in 7H9 broth. The MIC of eight drugs: amikacin (AMI), cefoxitin (FOX), ciprofloxacin (CIP), clarithromycin (CLA), doxycycline (DOX), linezolid (LZD), moxifloxacin (MXF) and trimethoprim-sulfamethoxazole (TMP-SMX) were evaluated against 76 RGM (18 species) using three methods (MH, MHR, and REMA) in a 96-well plate format incubated at 37 °C over 3-5 days. Results obtained in the MH plates were interpreted by the appearance of turbidity at the bottom of the well before adding the resazurin. MHR and 7H9-REMA plates were read by visual observation for a change in color from blue to pink. The majority of results were obtained at day 5 for MH and 1 day after for MHR and 7H9-REMA. However, the preliminary experiment on time to positivity results using the reference strain showed that the resazurin can be added to the MH at day 2 to produce the results at day 3, but future studies with large sets of strains are required to confirm this suggestion. A high level of agreement (kappa 1.000-0.884) was obtained between the MH and the MHR. Comparison of results obtained with 7H9-REMA, on the other hand, revealed several discrepancies and a lower level of agreement (kappa 1.000-0.111). The majority of the strains were resistant to DOX and TMP-SMX, and the most active antimicrobials for RGM were AMI and FOX. In the present study, MHR represented an excellent alternative for MIC determination of RGM. The results could be read reliably, more easily, and more quickly than with the classical MH method. PMID:25820290

  1. Molecular typing and antimicrobial susceptibility of Clostridium perfringens from broiler chickens.

    PubMed

    Gharaibeh, Saad; Al Rifai, Rami; Al-Majali, Ahmad

    2010-12-01

    Clostridium perfringens (Cp) causes necrotic enteritis disease in commercial poultry. Antimicrobials are used to control and treat this disease and sometimes clinical outbreaks do not respond well to certain treatments. This study was designed to isolate Cp from clinical cases, type these isolates by multiplex PCR, and determine their antimicrobial susceptibility by micro-dilution method. A total of 67 Cp isolates were obtained from 155 broiler chicken flocks. All isolates were classified as type A and non-enterotoxin producers. Lincomycin, erythromycins, and tilmicosin showed very high minimal inhibitory concentration (MIC) 50 of ≥256 μg/ml. However, tylosin, amoxicillin, ampicillin, penicillin, florfenicol, danofloxacin, enrofloxacin, chlortetracycline, doxycycline, and oxytetracycline had variable MIC₅₀ of 64, 0.5, 1, 1, 8, 4, 8, 4, 8, 0.5 μg/ml, respectively. It is recommended that Cp infections in Jordan be treated with either penicillins or tetracyclines especially amoxicillin and oxytetracycline. PMID:20969969

  2. Antimicrobial susceptibility of Escherichia coli isolated from feces of wild cranes migrating to Kagoshima, Japan.

    PubMed

    Kitadai, Noriyuki; Obi, Takeshi; Yamashita, Shogo; Murase, Toshiyuki; Takase, Kozo

    2012-03-01

    Susceptibility to 13 antimicrobial agents was examined for 138 Escherichia coli isolates obtained from 192 fecal samples of wild cranes that migrated for wintering to the Izumi plain, Kagoshima prefecture in Japan. The numbers of isolates that were resistant to the antimicrobials used in this study are as follows: oxytetracycline (OTC), 22 isolates; minocycline, 7 isolates; ampicillin (ABPC), 4 isolates; nalidixic acid, 4 isolates; enrofloxacin, 2 isolates; kanamycin, one isolate. Multidrug resistant isolates exhibiting 2-4 drug resistances were obtained. All of the OTC-resistant isolates carried either the tet (A) or tet(B) gene. The bla(TEM) gene was found in all of the ABPC-resistant isolates. PMID:22075707

  3. Antimicrobial susceptibilities of enterococci isolated from faeces of broiler and layer chickens.

    PubMed

    Yoshimura, H; Ishimaru, M; Endoh, Y S; Kojima, A

    2000-12-01

    Enterococci were isolated from faecal droppings of chickens in broiler and layer farms and the susceptibilities to nine therapeutic antimicrobial agents and six growth-promoting antibiotics were determined by the agar dilution method. Resistance to therapeutic antimicrobial agents such as ampicillin, clindamycin, erythromycin, streptomycin, tetracycline or tylosin was more frequent in enterococcal isolates from broiler farms than in those from layer farms. Resistance to ofloxacin was rare, occurring in only one (0.7%) of the Enterococcus faecium isolates from broiler farms. Resistance to growth-promoting antibiotics such as avilamycin, salinomycin and virginiamycin was common among isolates from broiler farms. Of the E. faecium isolates from broiler farms, 12.4% were resistant to avilamycin and 27.4% were resistant to virginiamycin. Resistance to salinomycin was detected in all enterococcal species, ranging from 12.4% of E. faecium isolates to 50% of E. hirae isolates. PMID:11123550

  4. Decreased susceptibility of Staphylococcus aureus small-colony variants toward human antimicrobial peptides.

    PubMed

    Gläser, Regine; Becker, Karsten; von Eiff, Christof; Meyer-Hoffert, Ulf; Harder, Jürgen

    2014-09-01

    Staphylococcus aureus is a frequent resident of human nose and skin in many individuals, but it is also able to cause a variety of serious infections including those of the skin and soft tissue. There is increasing evidence that particularly persistent, relapsing, and difficult-to-treat infections caused by S. aureus are associated with the formation of the small-colony variant (SCV) phenotype. The aim of this study was to investigate the hypothesis that (i) skin-derived antimicrobial peptides (AMPs) exhibit a reduced activity against SCVs and (ii) that switching into the SCV phenotype may endow S. aureus with a decreased susceptibility toward the killing activity of human stratum corneum. Here, we show that clinically derived S. aureus SCVs are less susceptible to the bactericidal activity of different human skin-derived AMPs as compared with their isogenic corresponding wild-type strains. Similarly, a S. aureus hemB mutant displaying the SCV phenotype was less susceptible to the antimicrobial activity of AMPs than its hemB-complemented mutant. These findings were accompanied by a higher resistance of SCVs to the killing activity of human stratum corneum. Switching into the SCV phenotype may help S. aureus to subvert cutaneous innate defense, thus contributing to the establishment and persistence of infection. PMID:24717245

  5. Increasing spectrum in antimicrobial resistance of Shigella isolates in Bangladesh: resistance to azithromycin and ceftriaxone and decreased susceptibility to ciprofloxacin.

    PubMed

    Rahman, Mahbubur; Shoma, Shereen; Rashid, Harunur; El Arifeen, Shams; Baqui, A H; Siddique, A K; Nair, G B; Sack, D A

    2007-06-01

    Antimicrobial resistance of Shigella isolates in Bangladesh, during 2001-2002, was studied and compared with that of 1991-1992 to identify the changes in resistance patterns and trends. A significant increase in resistance to trimethoprim-sulphamethoxazole (from 52% to 72%, p < 0.01) and nalidixic acid (from 19% to 51%, p < 0.01) was detected. High, but unchanged, resistance to tetracycline, ampicillin, and chloramphenicol, low resistance to mecillinam (resistance 3%, intermediate 3%), and to emergence of resistance to azithromycin (resistance 16%, intermediate 62%) and ceftriaxone/cefixime (2%) were detected in 2001-2002. Of 266 recent isolates, 63% were resistant to > or =3 anti-Shigella drugs (multidrug-resistant [MDR]) compared to 52% of 369 strains (p < 0.007) in 1991-1992. Of 154 isolates tested by E-test in 2001-2002, 71% were nalidixic acid-resistant (minimum inhibitory concentration [MIC] > or =32 microg/mL) and had 10-fold higher MIC90 (0.25 microg/mL) to ciprofloxacin than that of nalidixic acid-susceptible strains exhibiting decreased ciprofloxacin susceptibility, which were detected as ciprofloxacin-susceptible and nalidixic acid-resistant by the disc-diffusion method. These strains were frequently associated with MDR traits. High modal MICs were observed to azithromycin (MIC 6 microg/mL) and nalidixic acid (MIC 128 micdrog/mL) and low to ceftriaxone (MIC 0.023 microg/mL). Conjugative R-plasmids-encoded extended-spectrum beta-lactamase was responsible for resistance to ceftriaxone/cefixime. The growing antimicrobial resistance of Shigella is worrying and mandates monitoring of resistance. Pivmecillinam or ciprofloxacin might be considered for treating shigellosis with caution. PMID:17985817

  6. Increasing Spectrum in Antimicrobial Resistance of Shigella Isolates in Bangladesh: Resistance to Azithromycin and Ceftriaxone and Decreased Susceptibility to Ciprofloxacin

    PubMed Central

    Mahbubur, Rahman; Shoma, Shereen; Rashid, Harunur; Arifeen, Shams El; Baqui, A.H.; Siddique, A.K.; Nair, G.B.; Sack, D.A.

    2007-01-01

    Antimicrobial resistance of Shigella isolates in Bangladesh, during 2001-2002, was studied and compared with that of 1991-1992 to identify the changes in resistance patterns and trends. A significant increase in resistance to trimethoprim-sulphamethoxazole (from 52% to 72%, p<0.01) and nalidixic acid (from 19% to 51%, p<0.01) was detected. High, but unchanged, resistance to tetracycline, ampicillin, and chloramphenicol, low resistance to mecillinam (resistance 3%, intermediate 3%), and to emergence of resistance to azithromycin (resistance 16%, intermediate 62%) and ceftriaxone/cefixime (2%) were detected in 2001-2002. Of 266 recent isolates, 63% were resistant to ≥3 anti-Shigella drugs (multidrug-resistant [MDR]) compared to 52% of 369 strains (p<0.007) in 1991-1992. Of 154 isolates tested by E-test in 2001-2002, 71% were nalidixic acid-resistant (minimum inhibitory concentration [MIC] ≥32 μg/mL) and had 10-fold higher MIC90 (0.25 μg/mL) to ciprofloxacin than that of nalidixic acid-susceptible strains exhibiting decreased ciprofloxacin susceptibility, which were detected as ciprofloxacin-susceptible and nalidixic acid-resistant by the disc-diffusion method. These strains were frequently associated with MDR traits. High modal MICs were observed to azithromycin (MIC 6 μg/mL) and nalidixic acid (MIC 128 μg/mL) and low to ceftriaxone (MIC 0.023 μg/mL). Conjugative R-plasmids-encoded extended-spectrum ß-lactamase was responsible for resistance to ceftriaxone/cefixime. The growing antimicrobial resistance of Shigella is worrying and mandates monitoring of resistance. Pivmecillinam or ciprofloxacin might be considered for treating shigellosis with caution. PMID:17985817

  7. Diversity and antimicrobial susceptibility of Salmonella enterica serovars isolated from pig farms in Ibadan, Nigeria.

    PubMed

    Fashae, Kayode; Hendriksen, Rene S

    2014-01-01

    Animals including food animals play a significant role in the epidemiology of Salmonella enterica. The control requires identification of sources and institution of targeted interventions. This study investigates the diversity of S. enterica serovars, antimicrobial susceptibility, and occurrence of plasmid-mediated quinolone resistance (PMQR) genes in pigs in Ibadan, Nigeria. Pooled fresh pen floor fecal samples of pigs collected from 31 pig farms were cultured; the Salmonella isolates were serotyped and their antimicrobial susceptibility was determined. PMQR genes were screened by polymerase chain reaction. The 229 Salmonella isolates were made of 50 serovars predominated by rare serovars Salmonella Give (n = 36; 15.7 %), Salmonella Brancaster (n = 17; 7.4 %), Salmonella Colindale (n = 15; 6.6 %), Salmonella Elisaberthville (n = 13; 5.7 %), Salmonella Hillingdon (n = 13; 5.7 %), and Salmonella Kingston (n = 13; 5.7 %). The most widely distributed serovars among the farms were Salmonella Give (six farms) and Salmonella Elisaberthville (six farms). Resistance to chloramphenicol, sulfonamides, nalidixic acid, streptomycin, and tetracycline ranged from 11.6 % (n = 26) to 22.8 % (n = 51). Resistance ciprofloxacin and gentamicin was low (n = 2; 0.9 %). Multiply resistant isolates included Salmonella Kentucky, the most resistant serovar. qnrB19 was found in two isolates of Salmonella Corvallis and one isolate of Salmonella Larochelle, respectively, while qnrS1 was found in two isolates of Salmonella Derby. Other PMQR genes were not detected. Pigs constitute an important source of diverse Salmonella serovars in Ibadan. The isolates were more resistant to old antimicrobials with some multiple resistant. Control measures and regulation of antimicrobials are warranted. PMID:23893398

  8. Antimicrobial Non-Susceptibility of Escherichia coli from Outpatients and Patients Visiting Emergency Rooms in Taiwan

    PubMed Central

    Wang, Jann-Tay; Chang, Shan-Chwen; Chang, Feng-Yee; Fung, Chang-Phone; Chuang, Yin-Ching; Chen, Yao-Shen; Shiau, Yih-Ru; Tan, Mei-Chen; Wang, Hui-Ying; Lai, Jui-Fen; Huang, I-Wen; Yang Lauderdale, Tsai-Ling

    2015-01-01

    Longitudinal nationwide surveillance data on antimicrobial non-susceptibility and prevalence of extended-spectrum β-lactamases (ESBLs) as well as AmpC β-lactamases producers among Escherichia coli from different sources in the community settings are limited. Such data may impact treatment practice. The present study investigated E. coli from outpatients and patients visiting emergency rooms collected by the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program. A total of 3481 E. coli isolates were studied, including 2153 (61.9%) from urine and 1125 (32.3%) from blood samples. These isolates were collected biennially between 2002 and 2012 from a total of 28 hospitals located in different geographic regions of Taiwan. Minimum inhibitory concentrations (MIC) were determined using methods recommended by the Clinical Laboratory Standards Institute (CLSI). The prevalence and factors associated with the presence of ESBL and AmpC β-lactamase-producers were determined. Significant increases in non-susceptibility to most β-lactams and ciprofloxacin occurred during the study period. By 2012, non-susceptibility to cefotaxime and ciprofloxacin reached 21.1% and 26.9%, respectively. The prevalence of ESBL- and AmpC- producers also increased from 4.0% and 5.3%, respectively, in 2002–2004, to 10.7% for both in 2010–2012 (P < 0.001). The predominant ESBL and AmpC β-lactamase genes were CTX-M and CMY-types, respectively. Non-susceptibility of urine isolates to nitrofurantoin remained at around 8% and to fosfomycin was low (0.7%) but to cefazolin (based on the 2014 CLSI urine criteria) increased from 11.5% in 2002–2004 to 23.9% in 2010–2012 (P <0.001). Non-susceptibility of isolates from different specimen types was generally similar, but isolates from elderly patients were significantly more resistant to most antimicrobial agents and associated with the presence of ESBL- and AmpC- β-lactamases. An additional concern is that decreased ciprofloxacin

  9. Antimicrobial Non-Susceptibility of Escherichia coli from Outpatients and Patients Visiting Emergency Rooms in Taiwan.

    PubMed

    Wang, Jann-Tay; Chang, Shan-Chwen; Chang, Feng-Yee; Fung, Chang-Phone; Chuang, Yin-Ching; Chen, Yao-Shen; Shiau, Yih-Ru; Tan, Mei-Chen; Wang, Hui-Ying; Lai, Jui-Fen; Huang, I-Wen; Yang Lauderdale, Tsai-Ling

    2015-01-01

    Longitudinal nationwide surveillance data on antimicrobial non-susceptibility and prevalence of extended-spectrum β-lactamases (ESBLs) as well as AmpC β-lactamases producers among Escherichia coli from different sources in the community settings are limited. Such data may impact treatment practice. The present study investigated E. coli from outpatients and patients visiting emergency rooms collected by the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program. A total of 3481 E. coli isolates were studied, including 2153 (61.9%) from urine and 1125 (32.3%) from blood samples. These isolates were collected biennially between 2002 and 2012 from a total of 28 hospitals located in different geographic regions of Taiwan. Minimum inhibitory concentrations (MIC) were determined using methods recommended by the Clinical Laboratory Standards Institute (CLSI). The prevalence and factors associated with the presence of ESBL and AmpC β-lactamase-producers were determined. Significant increases in non-susceptibility to most β-lactams and ciprofloxacin occurred during the study period. By 2012, non-susceptibility to cefotaxime and ciprofloxacin reached 21.1% and 26.9%, respectively. The prevalence of ESBL- and AmpC- producers also increased from 4.0% and 5.3%, respectively, in 2002-2004, to 10.7% for both in 2010-2012 (P < 0.001). The predominant ESBL and AmpC β-lactamase genes were CTX-M and CMY-types, respectively. Non-susceptibility of urine isolates to nitrofurantoin remained at around 8% and to fosfomycin was low (0.7%) but to cefazolin (based on the 2014 CLSI urine criteria) increased from 11.5% in 2002-2004 to 23.9% in 2010-2012 (P <0.001). Non-susceptibility of isolates from different specimen types was generally similar, but isolates from elderly patients were significantly more resistant to most antimicrobial agents and associated with the presence of ESBL- and AmpC- β-lactamases. An additional concern is that decreased ciprofloxacin susceptibility (MIC

  10. Detection of Group B Streptococcus in Brazilian pregnant women and antimicrobial susceptibility patterns

    PubMed Central

    Castellano-Filho, Didier Silveira; da Silva, Vânia Lúcia; Nascimento, Thiago César; de Toledo Vieira, Marcel; Diniz, Cláudio Galuppo

    2010-01-01

    Group B Streptococcus (GBS) is still not routinely screened during pregnancy in Brazil, being prophylaxis and empirical treatment based on identification of risk groups. This study aimed to investigate GBS prevalence in Brazilian pregnant women by culture or polymerase chain reaction (PCR) associated to the enrichment culture, and to determine the antimicrobial susceptibility patterns of isolated bacteria, so as to support public health policies and empirical prophylaxis. After an epidemiological survey, vaginal and anorectal specimens were collected from 221 consenting laboring women. Each sample was submitted to enrichment culture and sheep blood agar was used to isolate suggestive GBS. Alternatively, specific PCR was performed from enrichment cultures. Antimicrobial susceptibility patterns were determined for isolated bacteria by agar diffusion method. No risk groups were identified. Considering the culture-based methodology, GBS was detected in 9.5% of the donors. Twenty five bacterial strains were isolated and identified. Through the culture-PCR methodology, GBS was detected in 32.6% specimens. Bacterial resistance was not detected against ampicillin, cephazolin, vancomycin and ciprofloxacin, whereas 22.7% were resistant to erythromycin and 50% were resistant to clindamycin. GBS detection may be improved by the association of PCR and enrichment culture. Considering that colony selection in agar plates may be laboring and technician-dependent, it may not reflect the real prevalence of streptococci. As in Brazil prevention strategies to reduce the GBS associated diseases have not been adopted, prospective studies are needed to anchor public health policies especially considering the regional GBS antimicrobial susceptibility patterns. PMID:24031585

  11. Serotyping, Genotyping, and Antimicrobial Susceptibility of Ornithobacterium rhinotracheale Isolates from Mexico.

    PubMed

    Peña-Vargas, Edgar Rafael; Vega-Sánchez, Vicente; Morales-Erasto, Vladimir; Trujillo-Ruíz, Héctor Hugo; Talavera-Rojas, Martín; Soriano-Vargas, Edgardo

    2016-09-01

    The bacterium Ornithobacterium rhinotracheale is associated with respiratory disease and septicemia in poultry. In this study, 9 reference strains and a total of 23 isolates of O. rhinotracheale from respiratory diseased poultry from Mexico were serotyped and genotyped. Furthermore, the antimicrobial susceptibility of isolates and reference strains of O. rhinotracheale were determined. All isolates belong to serotype A and showed a clonal relationship. All reference strains and isolates were resistant to colistin, fosfomycin, gentamicin, kanamycin, streptomycin, and trimethoprim-sulfamethoxazole. These results should eventually be helpful in planning strategies for the control of O. rhinotracheale infections in poultry in Mexico. PMID:27610728

  12. Antimicrobial susceptibility profiles of Helicobacter pylori isolated from patients in North India.

    PubMed

    Gehlot, Valentina; Mahant, Shweta; Mukhopadhyay, Asish Kumar; Das, Kunal; De, Ronita; Kar, Premashis; Das, Rajashree

    2016-06-01

    Helicobacter pylori-related gastroduodenal diseases are very common in India. Antibiotic resistance to commonly used antibiotics against H. pylori is increasing very rapidly. The aim of this study was to determine the antimicrobial susceptibility patterns of H. pylori strains from India against commonly used antibiotics in H. pylori treatment. Helicobacter pylori were cultured from 68 patients suffering from various gastroduodenal diseases in North India. Minimum inhibitory concentrations (MICs) to different antibiotics were determined by agar dilution. The clinical diagnosis of the 68 patients who were H. pylori culture-positive were gastro-oesophageal reflux disease (GERD) (n=23), non-erosive reflux disease (NERD) (n=22), non-ulcer dyspepsia (NUD) (n=13), antral gastritis (n=3), duodenal ulcer (n=2) and others (n=5). Of the 68 H. pylori isolates, 20 (29.4%) showed no resistance. The prevalence of drug resistance was 70.6%, including resistance to metronidazole (48.5%), furazolidone (22.1%), amoxicillin (17.6%), tetracycline (16.2%) and clarithromycin (11.8%). Dual and multiple drug resistance were found in 26.5% and 8.8% of cases, respectively. In conclusion, more than two-thirds of the isolated H. pylori strains showed resistance to at least one of the antibiotics for H. pylori treatment. Metronidazole resistance was most prevalent amongst the isolates tested. Emergence of dual and multidrug resistance is of great concern and there is an urgent need for regular antibiotic resistance surveillance studies. Amoxicillin- and clarithromycin-based anti-H. pylori regimens commonly prescribed for triple therapy in India show least resistance and hence are appropriate for anti-H. pylori management in India. PMID:27436467

  13. Comparison of agar dilution and antibiotic gradient strip test with broth microdilution for susceptibility testing of swine Brachyspira species.

    PubMed

    Mirajkar, Nandita S; Gebhart, Connie J

    2016-03-01

    Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics. PMID:26965233

  14. Antimicrobial susceptibility profiling and genomic diversity of Acinetobacter baumannii isolates: A study in western Iran

    PubMed Central

    Mohajeri, Parviz; Farahani, Abbas; Feizabadi, Mohammad Mehdi; Ketabi, Hosnieh; Abiri, Ramin; Najafi, Farid

    2013-01-01

    Background and Objective Acinetobacter baumannii is an aerobic non-motile Gram-negative bacterial pathogen that is resistant to most antibiotics. Carbapenems are the most common antibiotics for the treatment of infections caused by this pathogen. Mechanisms of antibiotic-resistance in A. baumannii are mainly mediated by efflux pumps-lactamases. The aim of this study was to determine antibiotic susceptibility, the possibility of existence of OXAs genes and fingerprinting by Pulsed-Field Gel Electrophoresis (PFGE) among clinical isolates of Acinetobacter collected from Kermanshah hospitals. Materials and Methods One hundred and four isolates were collected from patients attending Imam Reza, Taleghani and Imam Khomeini hospitals of Kermanshah (Iran). Isolates were identified by biochemical tests and API 20NE kit. The susceptibility to different antibiotics was assessed with Kirby-Bauer disk diffusion method. PCR was performed for detection of bla OXA-23, bla OXA-24, bla OXA-51 and bla OXA-58 beta-lactamase genes. Clonal relatedness was estimated by PFGE (with the restriction enzyme Apa I) and DNA patterns were analyzed by Gel compare II 6.5 software. Results All isolates showed high-level of resistance to imipenem, meropenem as well as to other antimicrobial agents, while no resistance to polymyxin B, colistin, tigecylcine and minocycline was observed. The bla OXA-23like and bla OXA-24 like were found among 77.9% and 19.2% of the isolates, respectively. All isolates were positive for bla OXA-51, but none produced any amplicon for bla OXA-58. PFGE genotype analysis suggested the existence of eight clones among the 104 strains [A (n = 35), B (n = 29), C (n = 19), D (n = 10), E (n = 4), F (n = 3), G (n = 3), H (n = 1)]. Clone A was the dominant clone in hospital settings particularly infection wards so that the isolates in this group, compared to the other clones, showed higher levels of resistance to antibiotics. Conclusion The bla OXA-51-like and bla OXA-23like were

  15. Antimicrobial susceptibility of Clostridium difficile isolated from neonatal pigs with enteritis.

    PubMed

    Post, Karen W; Songer, J Glenn

    2004-02-01

    The minimum inhibitory concentration (MIC) of eight antimicrobial agents was determined by the agar dilution method for 80 isolates of Clostridium difficile from neonatal pigs with enteritis. MICs(50) for erythromycin, tilmicosin, and tylosin were relatively low (0.25-0.50 microg/mL), but MICs(90) (64 or > or =256 microg/mL) suggest in vivo resistance of a proportion of isolates. Susceptibility to tetracycline varied widely, with MIC(50) and MIC(90) of 8 and 32 microg/mL, respectively. The MICs(90) for tiamulin (8 microg/mL) and virginiamycin (16 microg/mL) suggest moderate susceptibility. Bacitracin and ceftiofur (MICs(90) > or =256 microg/mL) have little activity against C. difficile. Tiamulin and virginiamycin may decrease fecal shedding of C. difficile by sows, and erythromycin, tetracycline, and tylosin may be useful for treatment of infected piglets. PMID:16701500

  16. Antimicrobial susceptibility monitoring of respiratory tract pathogens isolated from diseased cattle and pigs across Europe: the VetPath study.

    PubMed

    de Jong, Anno; Thomas, Valérie; Simjee, Shabbir; Moyaert, Hilde; El Garch, Farid; Maher, Kirsty; Morrissey, Ian; Butty, Pascal; Klein, Ulrich; Marion, Hervé; Rigaut, Delphine; Vallé, Michel

    2014-08-01

    VetPath is an ongoing pan-European antibiotic susceptibility monitoring programme collecting pathogens from diseased antimicrobial non-treated cattle, pigs and poultry. In the current study, 1001 isolates from cattle and pig respiratory tract infections were tested for their antimicrobial susceptibilities. Non-replicate lung samples or nasopharyngeal/nasal swabs were collected from animals with acute clinical signs in 11 countries during 2002-2006. Pasteurella multocida and Mannheimia haemolytica from cattle and P. multocida, Actinobacillus pleuropneumoniae and Streptococcus suis from pigs were isolated by standard methods. S. suis was also isolated from meningitis cases. MICs of 16 antibiotics were assessed centrally by broth microdilution following CLSI recommendations. Results were interpreted using CLSI breakpoints where available. P. multocida (231) and M. haemolytica (138) isolates were all susceptible to amoxicillin/clavulanic acid, ceftiofur, enrofloxacin and trimethoprim/sulfamethoxazole. Resistance to florfenicol and spectinomycin was 0.4% and 3.5% in P. multocida, respectively, and absent in M. haemolytica isolates. Tetracycline resistance was 5.7% and 14.6% for P. multocida and M. haemolytica. In pigs, 230 P. multocida, 220 A. pleuropneumoniae and 182 S. suis isolates were recovered. Resistance to amoxicillin/clavulanic acid, ceftiofur, enrofloxacin, florfenicol, tiamulin and tilmicosin was absent or <1%. Trimethoprim/sulfamethoxazole resistance was 3-6% and tetracycline resistance varied from 14.7% in A. pleuropneumoniae to 81.8% in S. suis. In conclusion, low resistance to antibiotics with defined clinical breakpoints, except for tetracycline, was observed among the major respiratory tract pathogens recovered from cattle and pigs. Since for approximately half of the antibiotics in this panel no CLSI-defined breakpoints were available, setting of the missing veterinary breakpoints is important. PMID:24837878

  17. Identification and susceptibility testing of Staphylococcus aureus by direct inoculation from positive BACTEC blood culture bottles.

    PubMed

    Diederen, B M W; Zieltjens, M; Wetten, H; Buiting, A G M

    2006-01-01

    This study explored the possibility of combining direct inoculation of tube coagulase and DNase tests, and the VITEK2 system, from BACTEC blood culture bottles in order to achieve rapid identification and susceptibility testing of Staphylococcus aureus. All isolates were identified correctly as S. aureus or coagulase-negative staphylococci (CNS). Antimicrobial susceptibility testing with the VITEK2 system gave 99.6% correct category agreement, with 0.1% very major errors and 0.3% minor errors among S. aureus isolates, and 97.4% correct category agreement, with 0.9% very major errors and 1.7% minor errors among CNS isolates. The results suggested that direct identification and susceptibility testing is sufficiently accurate for immediate reporting. PMID:16460552

  18. Properties and antimicrobial susceptibility of Trueperella pyogenes isolated from bovine mastitis in China.

    PubMed

    Alkasir, Rashad; Wang, Jianfang; Gao, Jian; Ali, Tariq; Zhang, Limei; Szenci, Ottó; Bajcsy, Árpád Csaba; Han, Bo

    2016-03-01

    Trueperella (T.) pyogenes is an opportunistic pathogen that causes suppurative diseases in domestic animals. In this work, the properties, pathogenesis and phenotypic diversity of T. pyogenes isolates from bovine mastitis were studied. Both pyolysin (plo) and collagen-binding protein (cbp) virulence factor genes were detected by PCR in all T. pyogenes isolates (n = 50). Using the tissue culture plate method, 90% of T. pyogenes isolates were able to form biofilms. The minimum inhibitory concentrations (MICs) of 13 antimicrobials against T. pyogenes isolates were determined. High susceptibility was observed to rifampin (96%), ampicillin (94%), ciprofloxacin (94%), and penicillin (92%), while low susceptibility was found to trimethoprim-sulphamethoxazole (10%) and bacitracin (2%). The intracellular assay revealed that T. pyogenes isolates had different cytopathogenic effects on cells. The high percentage (28.6%) of T. pyogenes isolates suggests that this bacterium is an important contributor to mastitis. Moreover, the high occurrence of multidrug resistance, biofilm production, intracellular survival, and the temporal dynamics of T. pyogenes interactions are key factors for a better understanding of how immunity acts on infections with these bacteria and how they evade immune surveillance, thus highlighting the need for the prudent use of antimicrobial agents in veterinary medicine. PMID:26919137

  19. The Resistant-Population Cutoff (RCOFF): a New Concept for Improved Characterization of Antimicrobial Susceptibility Patterns of Non-Wild-Type Bacterial Populations

    PubMed Central

    Valsesia, Giorgia; Hombach, Michael; Maurer, Florian P.; Courvalin, Patrice; Roos, Malgorzata

    2015-01-01

    This study aimed to determine resistant-population cutoffs (RCOFFs) to allow for improved characterization of antimicrobial susceptibility patterns in bacterial populations. RCOFFs can complement epidemiological cutoff (ECOFF)-based settings of clinical breakpoints (CBPs) by systematically describing the correlation between non-wild-type and wild-type populations. We illustrate this concept by describing three paradigmatic examples of wild-type and non-wild-type Escherichia coli populations from our clinical strain database of disk diffusion diameters. The statistical determination of RCOFFs and ECOFFs and their standardized applications in antimicrobial susceptibility testing (AST) facilitates the assignment of isolates to wild-type or non-wild-type populations. This should improve the correlation of in vitro AST data and distinct antibiotic resistance mechanisms with clinical outcome facilitating the setting and validation of CBPs. PMID:25762769

  20. Bacterial spectrum and antimicrobial susceptibility pattern of bloodstream infections in children with febrile neutropenia: experience of single center in southeast of Turkey.

    PubMed

    Aslan, Selda; Citak, Elvan Caglar; Yis, Reyhan; Degirmenci, Suleyman; Arman, Dilek

    2012-06-01

    Empirical antimicrobial therapy is usually started in febrile neutropenic patients without having culture results. The aim of this study was to help determine the policies of empirical antibiotic usage in febrile neutropenic children by detecting the antimicrobial susceptibility profile in this group of patients. In this study 811 blood cultures taken from neutropenic children hospitalized at the Department of Oncology of Gaziantep Children Hospital November 2007 and February 2010 were retrospectively evaluated. Blood cultures were routinely collected in aerobic and anaerobic media and incubated using the BACTEC system. Identification and antimicrobial susceptibility testing of the isolates to antimicrobial agents was performed using the Vitek2(®) system according to the recommendations of the Clinical and Laboratory Standards Institute. Of 811 isolates analyzed, 128 (56.4%) were gram positive cocci, 43 (18.9%) were gram negative bacilli and fungi accounted for 56 (24.7%). The main isolated Gram-positive bacteria from blood were coagulase-negative staphylococcus (56.7%), followed by methicillin-resistant Staphylococcus aureus (14.1%). S. aureus and Streptococcus spp. were all susceptible to linezolid, vancomycin and teicoplanin. S aureus was still susceptible to few other antimicrobial agents such as tetracycline (82.4%), chloramphenicol (55.6%). Seven E. faecium, 7 E. fecalis and 1 E. hirae was isolated from blood cultures. Vancomycin resistance was detected in 6 out of 15 (40%) Enterococcus spp. isolates. Among gram-negative bacteria E. coli (30.2%) was followed by Klebsiella pneumoniae (20.9%) and Proteus spp. (18.6%). Imipenem (89.2%), meropenem (86.6%), chloramphenicol (88.9%), amicasin (82.4%) and fosfomycin (81.3%) showed highest susceptibility in vitro activity against all Gram-negative isolates. To know the antimicrobial susceptibility profile of the pathogens frequently isolated from febrile neutropenic children and to consider this profile before

  1. Antimicrobial Susceptibilities of Health Care-Associated and Community-Associated Strains of Methicillin-Resistant Staphylococcus aureus from Hospitalized Patients in Canada, 1995 to 2008▿

    PubMed Central

    Simor, Andrew E.; Louie, Lisa; Watt, Christine; Gravel, Denise; Mulvey, Michael R.; Campbell, Jennifer; McGeer, Allison; Bryce, Elizabeth; Loeb, Mark; Matlow, Anne

    2010-01-01

    We determined the in vitro antimicrobial susceptibilities of 7,942 methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained from patients hospitalized in 48 Canadian hospitals from 1995 to 2008. Regional variations in susceptibilities were identified. The dissemination of community-associated strains in Canada appears to have contributed to increased susceptibility of MRSA to several non-β-lactam antimicrobial agents in the past decade. Reduced susceptibility to glycopeptides was not identified. PMID:20231402

  2. Virulence Genes and the Antimicrobial Susceptibility of Escherichia coli, Isolated from Wild Waterbirds, in the Netherlands and Poland.

    PubMed

    Kuczkowski, Maciej; Krawiec, Marta; Voslamber, Berend; Książczyk, Marta; Płoskońska-Bugla, Gabriela; Wieliczko, Alina

    2016-08-01

    Affiliation to four phylogroups (A, B1, B2, and D) was examined, among 190 Escherichia coli strains, collected from five, wild waterbird species, including the following: the Greylag goose-Anser anser (61) and the Canada goose-Branta canadensis (33) obtained in the Netherlands, and the Mallard-Anas platyrhynchos (38), the Mute swan-Cygnus olor (37), and the Great cormorant-Phalacrocorax carbo (21) obtained in Poland. Moreover, the prevalence of 10 virulence factors: astA, iss, iucD, irp2, papC, tsh, vat, cva/cvi, stx2f, and bfp, as well as antimicrobial susceptibility to amoxicillin, enrofloxacin, and tetracycline (minimum inhibitory concentration [MIC] using E-tests) were investigated, in the examined E. coli strains. Results demonstrated that the greatest number of E. coli strains belonged to phylogenetic groups, B1 (86 strains-45.3%) and D (49 strains-25.8%), whereas 40 (21.0%) and only 15 (7.9%) isolates were classified as being of phylogenetic groups, A and B2, respectively. Among the 10 tested virulence-associated genes, 7 genes were detected in 61 examined strains (32.1%) with highly varying frequency. Virulence profiles showed that astA, iss, and irp2 genes were detected most frequently among all examined E. coli strains, isolated from every chosen bird species. Antimicrobial susceptibility, as detected by MIC for the examined antibiotics, is variable among strains isolated from different species of birds. The aim of this study was to examine the prevalence of E. coli strains, isolated from different species of wild waterbirds and determine their potential pathogenicity to the environment, other birds, and people. PMID:27348207

  3. A two-hour antibiotic susceptibility test by ATP-bioluminescence.

    PubMed

    March Rosselló, Gabriel Alberto; García-Loygorri Jordán de Urries, María Cristina; Gutiérrez Rodríguez, María Purificación; Simarro Grande, María; Orduña Domingo, Antonio; Bratos Pérez, Miguel Ángel

    2016-01-01

    The antibiotic susceptibility test (AST) in Clinical Microbiology laboratories is still time-consuming, and most procedures take 24h to yield results. In this study, a rapid antimicrobial susceptibility test using ATP-bioluminescence has been developed. The design of method was performed using five ATCC collection strains of known susceptibility. This procedure was then validated against standard commercial methods on 10 strains of enterococci, 10 staphylococci, 10 non-fermenting gram negative bacilli, and 13 Enterobacteriaceae from patients. The agreement obtained in the sensitivity between the ATP-bioluminescence method and commercial methods (E-test, MicroScan and VITEK2) was 100%. In summary, the preliminary results obtained in this work show that the ATP-bioluminescence method could provide a fast and reliable AST in two hours. PMID:25979598

  4. Antimicrobial susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis isolated from community-acquired respiratory tract infections in China: Results from the CARTIPS Antimicrobial Surveillance Program.

    PubMed

    Zhang, Yawei; Zhang, Feifei; Wang, Hui; Zhao, Chunjiang; Wang, Zhanwei; Cao, Bin; Du, Yan; Feng, Xianju; Hu, Yunjian; Hu, Bijie; Ji, Ping; Liu, Zhiyong; Liu, Yong; Liao, Wanzhen; Lu, Juan; Sun, Hongli; Wang, Zhongxin; Xu, Xiuli; Xu, Xuesong; Yang, Qing; Yu, Yunsong; Zhang, Rong; Zhuo, Chao

    2016-06-01

    This study investigated the antimicrobial susceptibilities of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis isolates causing adult community-acquired respiratory tract infections (CARTIs) in China. A multicentre resistance surveillance study (CARTIPS) investigating 1046 clinical isolates from 19 hospitals in China was conducted from 2013 to 2014. Based on the minimum inhibitory concentration (MIC) breakpoints of oral penicillin, the percentages of penicillin-resistant, penicillin-intermediate and penicillin-susceptible S. pneumoniae were 44.1%, 13.7%, and 42.2%, respectively. The rates of penicillin-non-susceptible S. pneumoniae ranged from 27.9% to 72.2% in different cities, with the highest rate in Nanchang. Macrolides, including azithromycin, clarithromycin and erythromycin, showed the lowest activities against S. pneumoniae isolates, with resistance rates of 90.5%, 92.2% and 93.0%, respectively. However, 98% of these strains were susceptible to levofloxacin and moxifloxacin. For H. influenzae isolates, most of the antimicrobials agents exhibited good activities. However, ampicillin and trimethoprim/sulfamethoxazole showed relatively lower activity against H. influenzae, with resistance rates of 35.0% and 54.4%, respectively. β-lactamase production rates amongst H. influenzae and M. catarrhalis were 31.0% and 87.1%, respectively. In addition, a total of 15 β-lactamase-negative ampicillin-resistant (BLNAR) strains identified in this study were resistant to ampicillin, amoxicillin/clavulanic acid, cefaclor and cefuroxime. Most of the antimicrobial agents showed excellent activity against M. catarrhalis, with susceptibility rates of >90%. The results from the current study confirmed the regional variations in antimicrobial susceptibility of major CARTI pathogens and provided some choices for the treatment of these organisms. Continuous national surveillance of the epidemiology of CARTIs is strongly warranted in China. PMID:27436464

  5. Update: The National Antimicrobial Resistance Monitoring System Enteric Bacteria (NARMS): Animal Arm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing remains an important tool as investigators devise ways to arrest the development of antimicrobial resistance, particularly in food borne bacteria. In 1996, the Food and Drug Administration (FDA) initiated the National Antimicrobial Resistance Monitoring System -...

  6. Overview Of Antimicrobial Resistance In Food Borne Pathogens In The United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing remains an important tool as investigators devise ways to arrest the development of antimicrobial resistance, particularly in food borne bacteria. In 1996, the Food and Drug Administration (FDA) initiated the National Antimicrobial Resistance Monitoring System -...

  7. Characterization and Tracking of Antimicrobial Resistant Pathogens at Various Points along the Poultry Production Chain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing remains an important tool as investigators devise ways to arrest the development of antimicrobial resistance, particularly in food borne bacteria. In 1996, the Food and Drug Administration (FDA) initiated the National Antimicrobial Resistance Monitoring System -...

  8. Clinical impact of rapid in vitro susceptibility testing and bacterial identification.

    PubMed Central

    Doern, G V; Vautour, R; Gaudet, M; Levy, B

    1994-01-01

    During the past decade, a variety of instrument-assisted bacterial identification and antimicrobial susceptibility test systems have been developed which permit provision of test results in a matter of hours rather than days, as has been the case with traditional overnight procedures. These newer rapid techniques are much more expensive than older methods. It has been presumed but not proven that the clinical benefits of rapid testing to patients with infection offset the added cost. The intent of this study was to objectively define the clinical impact of rapid bacterial identification and antimicrobial susceptibility testing. A 1-year study was performed in which infected, hospitalized patients in a tertiary-care, teaching, medical center were randomly assigned to one of two groups: patients for whom identification and susceptibility testing was performed by using a semi-automated, rapid, same-day procedure and those for whom testing was accomplished by using traditional overnight techniques. The two groups were compared with respect to numerous demographic descriptors, and then patients were monitored prospectively through the end of their hospitalization with the aim of determining whether there existed objectively defineable differences in management and outcome between the two groups. The mean lengths of time to provision of susceptibility and identification test results in the rapid test group were 11.3 and 9.6 h, respectively. In the overnight test group, these values were 19.6 and 25.9 h, respectively (P < 0.0005). There were 273 evaluable patients in the first group and 300 in the second group. Other than the length of time required to provide susceptibility and identification test results, no significant differences were noted between the two groups with respect to > 100 demographic descriptors. With regard to measures of outcome, the mean lengths of hospitalization were also the same in both groups. Mortality rates were however, lower in the rapid test

  9. Methicillin-resistant Staphylococcus aureus in Stockholm, Sweden: Molecular epidemiology and antimicrobial susceptibilities to ceftaroline, linezolid, mupirocin and vancomycin in 2014.

    PubMed

    Fang, Hong; Fröding, Inga; Gian, Boisan; Hæggman, Sara; Tollström, Ulla-Britt; Ullberg, Måns; Nord, Carl Erik

    2016-06-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is a public health problem worldwide. The aim of the present study was to investigate the molecular epidemiology and antimicrobial susceptibilities of MRSA strains in Stockholm, Sweden in 2014. Pulsed-field gel electrophoresis (PFGE) was used to characterise the strains. Antimicrobial susceptibilities to ceftaroline, linezolid and mupirocin were determined by the disc diffusion method. Etest was used to determine vancomycin susceptibility and to confirm resistance to ceftaroline, mupirocin and linezolid in non-susceptible strains. High-level ceftaroline-resistant strains [minimum inhibitory concentration (MIC)≥4mg/L] were confirmed by the broth microdilution method. spa typing was carried out on strains that were non-susceptible to the antibiotics tested. In total, 743 consecutive non-duplicate MRSA strains recovered in Stockholm in 2014 were investigated. PFGE analysis of the isolates revealed a population with 271 different PFGE patterns and three non-typeable strains. No PFGE type accounted for >10% of all strains. The most common PFGE types were MRSA-00-02 (6.9%) and MRSA-05-02 (4.6%). MRSA-05-02 is a USA300-like strain. The antimicrobial susceptibilities of the strains were as follows: ceftaroline, 98.5%; linezolid, 100%; mupirocin, 99.3%; and vancomycin, 100%. Two strains with spa t001 displayed ceftaroline MICs of 4mg/L. Three strains with spa types t002, t064 and t437 showed high-level mupirocin resistance (MIC>1024mg/L). In conclusion, there was a diverse genetic population among the MRSA isolates and no predominant genotype was found. This study identified a few strains with high-level ceftaroline resistance, high-level mupirocin resistance and high-risk genotypes. PMID:27436463

  10. Awareness of Cancer Susceptibility Genetic Testing

    PubMed Central

    Mai, Phuong L.; Vadaparampil, Susan Thomas; Breen, Nancy; McNeel, Timothy S.; Wideroff, Louise; Graubard, Barry I.

    2014-01-01

    Background Genetic testing for several cancer susceptibility syndromes is clinically available; however, existing data suggest limited population awareness of such tests. Purpose To examine awareness regarding cancer genetic testing in the U.S. population aged ≥25 years in the 2000, 2005, and 2010 National Health Interview Surveys. Methods The weighted percentages of respondents aware of cancer genetic tests, and percent changes from 2000–2005 and 2005–2010, overall and by demographic, family history, and healthcare factors were calculated. Interactions were used to evaluate the patterns of change in awareness between 2005 and 2010 among subgroups within each factor. To evaluate associations with awareness in 2005 and 2010, percentages were adjusted for covariates using multiple logistic regression. The analysis was performed in 2012. Results Awareness decreased from 44.4% to 41.5% (p<0.001) between 2000 and 2005, and increased to 47.0% (p<0.001) in 2010. Awareness increased between 2005 and 2010 in most subgroups, particularly among individuals in the South (p-interaction=0.03) or with a usual place of care (p-interaction=0.01). In 2005 and 2010, awareness was positively associated with personal or family cancer history and high perceived cancer risk, and inversely associated with racial/ethnic minorities, age 25–39 or ≥60 years, male gender, lower education and income levels, public or no health insurance, and no provider contact in 12 months. Conclusions Despite improvement from 2005 to 2010, ≤50% of the U.S. adult population was aware of cancer genetic testing in 2010. Notably, disparities persist for racial/ethnic minorities and individuals with limited health care access or income. PMID:24745633

  11. ANTIMICROBIAL EFFICACY TESTING (IN-HOUSE)

    EPA Science Inventory

    This project initiates the in-house study of antimicrobial efficacy, growth parameters, and transport characteristics of biological contaminants. Viable and non-viable microbial analysis will be performed by growth culture and molecular biology techniques.

    Experiments w...

  12. Antimicrobial susceptibility, virulence determinant carriage and molecular characteristics of Staphylococcus aureus isolates associated with skin and soft tissue infections.

    PubMed

    Yu, Fangyou; Liu, Yunling; Lv, Jinnan; Qi, Xiuqin; Lu, Chaohui; Ding, Yu; Li, Dan; Liu, Huanle; Wang, Liangxing

    2015-01-01

    A better understanding of the antimicrobial susceptibility, carriage of virulence determinants and molecular characteristics of Staphylococcus aureus isolates associated with skin and soft tissue infections (SSTIs) may provide further insights related to clinical outcomes with these infections. From January 2012 to September 2013, a total of 128 non-duplicate S. aureus isolates were recovered from patients with SSTIs. All 128 S. aureus SSTI isolates carried at least five virulence genes tested. Virulence genes detected among at least 70% of all tested isolates included hld (100%), hla (95.3%), icaA (96.9%), clf (99.2%), sdrC (79.7%), sdrD (70.3%), and sdrE (72.7%). The prevalence of MRSA isolates with 10 virulence genes tested (54.4%, 31/56) was significantly higher than that among MSSA isolates (35.2%, 25/71) (p<0.05). The positive rates of seb, sen, sem, sdrE and pvl among MRSA isolates were significantly higher than among MSSA isolates (p<0.05). ST7 and ST630 accounting for 10.9% were found to be the predominant STs. The most prevalent spa type was t091 (8.6%). MRSA-ST59-SCCmec IV was the most common clone (12.3%) among MRSA isolates whereas among MSSA isolates the dominant clone was MSSA-ST7 (15.5%). Six main clonal complexes (CCs) were found, including CC5 (52.3%), CC7 (11.7%), CC59 (8.6%), CC88 (6.3%), CC398 (4.7%), and CC121 (3.1%). A higher carriage of seb and sec was found among CC59 isolates. In comparison to CC5 and CC7 isolates, those with the highest carriage rates (>80.0%) of sdrC and sdrD, CC59 isolates had lower prevalence of these two virulence genes. All CC59 isolates were susceptible to gentamicin and trimethoprim/sulfamethoxazole, while CC5 and CC7 isolates had resistance rates to these two antimicrobials of 25.4% and 20.9%, and 40.0% and 40.0%, respectively. The resistance rates for tetracycline, clindamycin, and erythromycin among CC5 isolates were lower than among CC7 and CC59 isolates. In conclusion, the molecular typing of S. aureus SSTI

  13. Serotypes, virulence factors, and antimicrobial susceptibilities of vaginal and fecal isolates of Escherichia coli from giant pandas.

    PubMed

    Wang, Xin; Yan, Qigui; Xia, Xiaodong; Zhang, Yanming; Li, Desheng; Wang, Chengdong; Chen, Shijie; Hou, Rong

    2013-09-01

    Although Escherichia coli typically colonizes the intestinal tract and vagina of giant pandas, it has caused enteric and systemic disease in giant pandas and greatly impacts the health and survival of this endangered species. In order to understand the distribution and characteristics of E. coli from giant pandas, 67 fecal and 30 vaginal E. coli isolates from 21 giant pandas were characterized for O serogroups, phylogenetic groups, antimicrobial susceptibilities, and pulsed-field gel electrophoresis (PFGE) profiles. In addition, these isolates were tested for the presence of extraintestinal pathogenic E. coli (ExPEC) and diarrheagenic E. coli (DEC) by multiplex PCR detection of specific virulence genes. The most prevalent serogroups for all E. coli isolates were O88, O18, O167, O4, and O158. ExPEC isolates were detected mostly in vaginal samples, and DEC isolates were detected only in fecal samples. Phylogenetic group B1 predominated in fecal isolates, while groups B2 and D were frequently detected in vaginal isolates. Resistance to trimethoprim-sulfamethoxazole was most frequently observed, followed by resistance to nalidixic acid and tetracycline. All except five isolates were typeable by using XbaI and were categorized into 74 PFGE patterns. Our findings indicate that panda E. coli isolates exhibited antimicrobial resistance, and potentially pathogenic E. coli isolates were present in giant pandas. In addition, these E. coli isolates were genetically diverse. This study may provide helpful information for developing strategies in the future to control E. coli infections of giant pandas. PMID:23793635

  14. Serotypes, Virulence Factors, and Antimicrobial Susceptibilities of Vaginal and Fecal Isolates of Escherichia coli from Giant Pandas

    PubMed Central

    Wang, Xin; Xia, Xiaodong; Li, Desheng; Wang, Chengdong; Chen, Shijie; Hou, Rong

    2013-01-01

    Although Escherichia coli typically colonizes the intestinal tract and vagina of giant pandas, it has caused enteric and systemic disease in giant pandas and greatly impacts the health and survival of this endangered species. In order to understand the distribution and characteristics of E. coli from giant pandas, 67 fecal and 30 vaginal E. coli isolates from 21 giant pandas were characterized for O serogroups, phylogenetic groups, antimicrobial susceptibilities, and pulsed-field gel electrophoresis (PFGE) profiles. In addition, these isolates were tested for the presence of extraintestinal pathogenic E. coli (ExPEC) and diarrheagenic E. coli (DEC) by multiplex PCR detection of specific virulence genes. The most prevalent serogroups for all E. coli isolates were O88, O18, O167, O4, and O158. ExPEC isolates were detected mostly in vaginal samples, and DEC isolates were detected only in fecal samples. Phylogenetic group B1 predominated in fecal isolates, while groups B2 and D were frequently detected in vaginal isolates. Resistance to trimethoprim-sulfamethoxazole was most frequently observed, followed by resistance to nalidixic acid and tetracycline. All except five isolates were typeable by using XbaI and were categorized into 74 PFGE patterns. Our findings indicate that panda E. coli isolates exhibited antimicrobial resistance, and potentially pathogenic E. coli isolates were present in giant pandas. In addition, these E. coli isolates were genetically diverse. This study may provide helpful information for developing strategies in the future to control E. coli infections of giant pandas. PMID:23793635

  15. Antimicrobial susceptibility pattern of Staphylococcus aureus isolated from clinical specimens in Northern area of Jordan

    PubMed Central

    Al-Zoubi, Mazhar Salim; Al-Tayyar, Ibrahim Ali; Hussein, Emad; Jabali, Alla Al; Khudairat, Salih

    2015-01-01

    Background and Objectives: The global spread of methicillin resistant Staphylococcus aureus (MRSA) constitutes one of the most serious contemporary challenges to the treatment of hospital-acquired infections. We aimed to screen and assess the antibiotic susceptibility pattern of Staphylococcus aureus isolated from clinical specimens in local hospitals of Northern province in Jordan. Materials and Methods: Staphylococcus aureus was isolated and identified using standard methods from various clinical specimens of different infected body sites from 358 patients during the period from January 2008 to November 2012. Results: Our analysis showed that 31.6% of S. aureus infections were MRSA, while 31% were multidrug resistance (MDR) and 42.7% were Oxacillin-resistant (ORSA). Most of these strains were isolated from wound specimens. All isolates were susceptible to vancomycin (100%). They were also susceptible to chloramphenicol, linezolid, nitrofurantoin, rifampicin and teicoplanin (>80%), but showed resistance to erythromycin and penicillin. Conclusion: Vancomycin was the most effective antimicrobial agent against S. aureus. We recommend regular surveillance of hospital associated infections and monitoring antibiotic sensitivity pattern and strict drug policy for antibiotics used within and outside the hospital environments. PMID:26719783

  16. Trends towards lower antimicrobial susceptibility and characterization of acquired resistance among clinical isolates of Brachyspira hyodysenteriae in Spain.

    PubMed

    Hidalgo, Álvaro; Carvajal, Ana; Vester, Birte; Pringle, Märit; Naharro, Germán; Rubio, Pedro

    2011-07-01

    The antimicrobial susceptibility of clinical isolates of Brachyspira hyodysenteriae in Spain was monitored, and the underlying molecular mechanisms of resistance were investigated. MICs of tylosin, tiamulin, valnemulin, lincomycin, and tylvalosin were determined for 87 B. hyodysenteriae isolates recovered from 2008 to 2009 by broth dilution. Domain V of the 23S rRNA gene and the ribosomal protein L3 gene were sequenced in 20 isolates for which the tiamulin MIC was ≥ 4 μg/ml, presenting decreased susceptibility, and in 18 tiamulin-susceptible isolates (MIC ≤ 0.125 μg/ml), and all isolates were typed by multiple-locus variable-number tandem repeats analysis. A comparison with antimicrobial susceptibility data from 2000 to 2007 showed an increase in pleuromutilin resistance over time, doubling the number of isolates with decreased susceptibility to tiamulin. No alteration in susceptibility was detected for lincomycin, and the MIC of tylosin remained high (MIC(50) > 128 μg/ml). The decreased susceptibility to tylosin and lincomycin can be explained by mutations at position A2058 of the 23S rRNA gene (Escherichia coli numbering). A2058T was the predominant mutation, but A2058G also was found together with a change of the neighboring base pair at positions 2057 to 2611. The role of additional point mutations in the vicinity of the peptidyl transferase center and mutations in the L3 at amino acids 148 and 149 and their possible involvement in antimicrobial susceptibility are considered. An association between G2032A and high levels of tiamulin and lincomycin MICs was found, suggesting an increasing importance of this mutation in antimicrobial resistance of clinical isolates of B. hyodysenteriae. PMID:21555771

  17. Long-term evaluation of the antimicrobial susceptibility and microbial profile of subgingival biofilms in individuals with aggressive periodontitis

    PubMed Central

    Lourenço, Talita Gomes Baêta; Heller, Débora; do Souto, Renata Martins; Silva-Senem, Mayra Xavier e; Varela, Victor Macedo; Torres, Maria Cynesia Barros; Feres-Filho, Eduardo Jorge; Colombo, Ana Paula Vieira

    2015-01-01

    This study evaluates the antimicrobial susceptibility and composition of subgingival biofilms in generalized aggressive periodontitis (GAP) patients treated using mechanical/antimicrobial therapies, including chlorhexidine (CHX), amoxicillin (AMX) and metronidazole (MET). GAP patients allocated to the placebo (C, n = 15) or test group (T, n = 16) received full-mouth disinfection with CHX, scaling and root planning, and systemic AMX (500 mg)/MET (250 mg) or placebos. Subgingival plaque samples were obtained at baseline, 3, 6, 9 and 12 months post-therapy from 3–4 periodontal pockets, and the samples were pooled and cultivated under anaerobic conditions. The minimum inhibitory concentrations (MICs) of AMX, MET and CHX were assessed using the microdilution method. Bacterial species present in the cultivated biofilm were identified by checkerboard DNA-DNA hybridization. At baseline, no differences in the MICs between groups were observed for the 3 antimicrobials. In the T group, significant increases in the MICs of CHX (p < 0.05) and AMX (p < 0.01) were detected during the first 3 months; however, the MIC of MET decreased at 12 months (p < 0.05). For several species, the MICs significantly changed over time in both groups, i.e., Streptococci MICs tended to increase, while for several periodontal pathogens, the MICs diminished. A transitory increase in the MIC of the subgingival biofilm to AMX and CHX was observed in GAP patients treated using enhanced mechanical therapy with topical CHX and systemic AMX/MET. Both protocols presented limited effects on the cultivable subgingival microbiota. PMID:26273264

  18. Long-term evaluation of the antimicrobial susceptibility and microbial profile of subgingival biofilms in individuals with aggressive periodontitis.

    PubMed

    Lourenço, Talita Gomes Baêta; Heller, Débora; do Souto, Renata Martins; Silva-Senem, Mayra Xavier E; Varela, Victor Macedo; Torres, Maria Cynesia Barros; Feres-Filho, Eduardo Jorge; Colombo, Ana Paula Vieira

    2015-06-01

    This study evaluates the antimicrobial susceptibility and composition of subgingival biofilms in generalized aggressive periodontitis (GAP) patients treated using mechanical/antimicrobial therapies, including chlorhexidine (CHX), amoxicillin (AMX) and metronidazole (MET). GAP patients allocated to the placebo (C, n = 15) or test group (T, n = 16) received full-mouth disinfection with CHX, scaling and root planning, and systemic AMX (500 mg)/MET (250 mg) or placebos. Subgingival plaque samples were obtained at baseline, 3, 6, 9 and 12 months post-therapy from 3-4 periodontal pockets, and the samples were pooled and cultivated under anaerobic conditions. The minimum inhibitory concentrations (MICs) of AMX, MET and CHX were assessed using the microdilution method. Bacterial species present in the cultivated biofilm were identified by checkerboard DNA-DNA hybridization. At baseline, no differences in the MICs between groups were observed for the 3 antimicrobials. In the T group, significant increases in the MICs of CHX (p < 0.05) and AMX (p < 0.01) were detected during the first 3 months; however, the MIC of MET decreased at 12 months (p < 0.05). For several species, the MICs significantly changed over time in both groups, i.e., Streptococci MICs tended to increase, while for several periodontal pathogens, the MICs diminished. A transitory increase in the MIC of the subgingival biofilm to AMX and CHX was observed in GAP patients treated using enhanced mechanical therapy with topical CHX and systemic AMX/MET. Both protocols presented limited effects on the cultivable subgingival microbiota. PMID:26273264

  19. A Microfluidic Channel Method for Rapid Drug-Susceptibility Testing of Pseudomonas aeruginosa

    PubMed Central

    Matsumoto, Yoshimi; Grushnikov, Andrey; Kikuchi, Kazuma; Noji, Hiroyuki; Yamaguchi, Akihito; Yagi, Yasushi

    2016-01-01

    The recent global increase in the prevalence of antibiotic-resistant bacteria and lack of development of new therapeutic agents emphasize the importance of selecting appropriate antimicrobials for the treatment of infections. However, to date, the development of completely accelerated drug susceptibility testing methods has not been achieved despite the availability of a rapid identification method. We proposed an innovative rapid method for drug susceptibility testing for Pseudomonas aeruginosa that provides results within 3 h. The drug susceptibility testing microfluidic (DSTM) device was prepared using soft lithography. It consisted of five sets of four microfluidic channels sharing one inlet slot, and the four channels are gathered in a small area, permitting simultaneous microscopic observation. Antimicrobials were pre-introduced into each channel and dried before use. Bacterial suspensions in cation-adjusted Mueller–Hinton broth were introduced from the inlet slot and incubated for 3 h. Susceptibilities were microscopically evaluated on the basis of differences in cell numbers and shapes between drug-treated and control cells, using dedicated software. The results of 101 clinically isolated strains of P. aeruginosa obtained using the DSTM method strongly correlated with results obtained using the ordinary microbroth dilution method. Ciprofloxacin, meropenem, ceftazidime, and piperacillin caused elongation in susceptible cells, while meropenem also induced spheroplast and bulge formation. Morphological observation could alternatively be used to determine the susceptibility of P. aeruginosa to these drugs, although amikacin had little effect on cell shape. The rapid determination of bacterial drug susceptibility using the DSTM method could also be applicable to other pathogenic species, and it could easily be introduced into clinical laboratories without the need for expensive instrumentation. PMID:26872134

  20. A Microfluidic Channel Method for Rapid Drug-Susceptibility Testing of Pseudomonas aeruginosa.

    PubMed

    Matsumoto, Yoshimi; Sakakihara, Shouichi; Grushnikov, Andrey; Kikuchi, Kazuma; Noji, Hiroyuki; Yamaguchi, Akihito; Iino, Ryota; Yagi, Yasushi; Nishino, Kunihiko

    2016-01-01

    The recent global increase in the prevalence of antibiotic-resistant bacteria and lack of development of new therapeutic agents emphasize the importance of selecting appropriate antimicrobials for the treatment of infections. However, to date, the development of completely accelerated drug susceptibility testing methods has not been achieved despite the availability of a rapid identification method. We proposed an innovative rapid method for drug susceptibility testing for Pseudomonas aeruginosa that provides results within 3 h. The drug susceptibility testing microfluidic (DSTM) device was prepared using soft lithography. It consisted of five sets of four microfluidic channels sharing one inlet slot, and the four channels are gathered in a small area, permitting simultaneous microscopic observation. Antimicrobials were pre-introduced into each channel and dried before use. Bacterial suspensions in cation-adjusted Mueller-Hinton broth were introduced from the inlet slot and incubated for 3 h. Susceptibilities were microscopically evaluated on the basis of differences in cell numbers and shapes between drug-treated and control cells, using dedicated software. The results of 101 clinically isolated strains of P. aeruginosa obtained using the DSTM method strongly correlated with results obtained using the ordinary microbroth dilution method. Ciprofloxacin, meropenem, ceftazidime, and piperacillin caused elongation in susceptible cells, while meropenem also induced spheroplast and bulge formation. Morphological observation could alternatively be used to determine the susceptibility of P. aeruginosa to these drugs, although amikacin had little effect on cell shape. The rapid determination of bacterial drug susceptibility using the DSTM method could also be applicable to other pathogenic species, and it could easily be introduced into clinical laboratories without the need for expensive instrumentation. PMID:26872134

  1. Streptococcus suis in employees and the environment of swine slaughterhouses in São Paulo, Brazil: Occurrence, risk factors, serotype distribution, and antimicrobial susceptibility

    PubMed Central

    Soares, Taíssa Cook Siqueira; Gottschalk, Marcelo; Lacouture, Sonia; Megid, Jane; Ribolla, Paulo Eduardo Martins; de Figueiredo Pantoja, José Carlos; Paes, Antonio Carlos

    2015-01-01

    Streptococcus suis is an important pathogen in the swine industry. This article is the first to report the occurrence, risk factors, serotype distribution, and antimicrobial susceptibility of S. suis recovered from employees and environmental samples of swine slaughterhouses in Brazil. Tonsillar swabs from all 139 pig-slaughtering employees and 261 environmental swabs were collected for detection of S. suis and serotyping by monoplex and multiplex polymerase chain reaction, respectively. Antimicrobial susceptibility was determined by the disk-diffusion method. Although S. suis was not detected in any of the tested employees, it was isolated from 25% of the environmental samples. Significant differences (P < 0.05) in the occurrence of S. suis were observed between slaughterhouses and between areas of low, medium, and high risk. The most frequent serotypes were 4 and 29, each accounting for 12% of the isolates, followed by 5, 12, 21, and 31, each accounting for 6%. High rates of susceptibility to the antimicrobials doxycycline (100%), ceftiofur (94%), ampicillin (81%), and cephalexin (75%) were observed. However, multidrug resistance was observed in all the isolates. Because S. suis is present in the environment of swine slaughterhouses, on carcasses and knives, as well as on the hands of employees in all areas, all employees are at risk of infection. PMID:26424907

  2. Streptococcus suis in employees and the environment of swine slaughterhouses in São Paulo, Brazil: Occurrence, risk factors, serotype distribution, and antimicrobial susceptibility.

    PubMed

    Soares, Taíssa Cook Siqueira; Gottschalk, Marcelo; Lacouture, Sonia; Megid, Jane; Ribolla, Paulo Eduardo Martins; Pantoja, José Carlos de Figueiredo; Paes, Antonio Carlos

    2015-10-01

    Streptococcus suis is an important pathogen in the swine industry. This article is the first to report the occurrence, risk factors, serotype distribution, and antimicrobial susceptibility of S. suis recovered from employees and environmental samples of swine slaughterhouses in Brazil. Tonsillar swabs from all 139 pig-slaughtering employees and 261 environmental swabs were collected for detection of S. suis and serotyping by monoplex and multiplex polymerase chain reaction, respectively. Antimicrobial susceptibility was determined by the disk-diffusion method. Although S. suis was not detected in any of the tested employees, it was isolated from 25% of the environmental samples. Significant differences (P < 0.05) in the occurrence of S. suis were observed between slaughterhouses and between areas of low, medium, and high risk. The most frequent serotypes were 4 and 29, each accounting for 12% of the isolates, followed by 5, 12, 21, and 31, each accounting for 6%. High rates of susceptibility to the antimicrobials doxycycline (100%), ceftiofur (94%), ampicillin (81%), and cephalexin (75%) were observed. However, multidrug resistance was observed in all the isolates. Because S. suis is present in the environment of swine slaughterhouses, on carcasses and knives, as well as on the hands of employees in all areas, all employees are at risk of infection. PMID:26424907

  3. A Rapid Molecular Test for Determining Yersinia pestis Susceptibility to Ciprofloxacin by the Quantification of Differentially Expressed Marker Genes

    PubMed Central

    Steinberger-Levy, Ida; Shifman, Ohad; Zvi, Anat; Ariel, Naomi; Beth-Din, Adi; Israeli, Ofir; Gur, David; Aftalion, Moshe; Maoz, Sharon; Ber, Raphael

    2016-01-01

    Standard antimicrobial susceptibility tests used to determine bacterial susceptibility to antibiotics are growth dependent and time consuming. The long incubation time required for standard tests may render susceptibility results irrelevant, particularly for patients infected with lethal bacteria that are slow growing on agar but progress rapidly in vivo, such as Yersinia pestis. Here, we present an alternative approach for the rapid determination of antimicrobial susceptibility, based on the quantification of the changes in the expression levels of specific marker genes following exposure to growth-inhibiting concentrations of the antibiotic, using Y. pestis and ciprofloxacin as a model. The marker genes were identified by transcriptomic DNA microarray analysis of the virulent Y. pestis Kimberley53 strain after exposure to specific concentrations of ciprofloxacin for various time periods. We identified several marker genes that were induced following exposure to growth-inhibitory concentrations of ciprofloxacin, and we confirmed the marker expression profiles at additional ciprofloxacin concentrations using quantitative RT-PCR. Eleven candidate marker transcripts were identified, of which four mRNA markers were selected for a rapid quantitative RT-PCR susceptibility test that correctly determined the Minimal Inhibitory Concentration (MIC) values and the categories of susceptibility of several Y. pestis strains and isolates harboring various ciprofloxacin MIC values. The novel molecular susceptibility test requires just 2 h of antibiotic exposure in a 7-h overall test time, in contrast to the 24 h of antibiotic exposure required for a standard microdilution test. PMID:27242774

  4. A Rapid Molecular Test for Determining Yersinia pestis Susceptibility to Ciprofloxacin by the Quantification of Differentially Expressed Marker Genes.

    PubMed

    Steinberger-Levy, Ida; Shifman, Ohad; Zvi, Anat; Ariel, Naomi; Beth-Din, Adi; Israeli, Ofir; Gur, David; Aftalion, Moshe; Maoz, Sharon; Ber, Raphael

    2016-01-01

    Standard antimicrobial susceptibility tests used to determine bacterial susceptibility to antibiotics are growth dependent and time consuming. The long incubation time required for standard tests may render susceptibility results irrelevant, particularly for patients infected with lethal bacteria that are slow growing on agar but progress rapidly in vivo, such as Yersinia pestis. Here, we present an alternative approach for the rapid determination of antimicrobial susceptibility, based on the quantification of the changes in the expression levels of specific marker genes following exposure to growth-inhibiting concentrations of the antibiotic, using Y. pestis and ciprofloxacin as a model. The marker genes were identified by transcriptomic DNA microarray analysis of the virulent Y. pestis Kimberley53 strain after exposure to specific concentrations of ciprofloxacin for various time periods. We identified several marker genes that were induced following exposure to growth-inhibitory concentrations of ciprofloxacin, and we confirmed the marker expression profiles at additional ciprofloxacin concentrations using quantitative RT-PCR. Eleven candidate marker transcripts were identified, of which four mRNA markers were selected for a rapid quantitative RT-PCR susceptibility test that correctly determined the Minimal Inhibitory Concentration (MIC) values and the categories of susceptibility of several Y. pestis strains and isolates harboring various ciprofloxacin MIC values. The novel molecular susceptibility test requires just 2 h of antibiotic exposure in a 7-h overall test time, in contrast to the 24 h of antibiotic exposure required for a standard microdilution test. PMID:27242774

  5. Antimicrobials

    PubMed Central

    Murphy, Eileen F.; Clarke, Siobhan F.; Marques, Tatiana M.; Hill, Colin; Stanton, Catherine; Ross, R. Paul; O’Doherty, Robert M.; Shanahan, Fergus; Cotter, Paul D.

    2013-01-01

    Obesity is associated with a number of serious health consequences, including type 2 diabetes, cardiovascular disease and a variety of cancers among others and has been repeatedly shown to be associated with a higher risk of mortality. The relatively recent discovery that the composition and metabolic activity of the gut microbiota may affect the risk of developing obesity and related disorders has led to an explosion of interest in this distinct research field. A corollary of these findings would suggest that modulation of gut microbial populations can have beneficial effects with respect to controlling obesity. In this addendum, we summarize our recent data, showing that therapeutic manipulation of the microbiota using different antimicrobial strategies may be a useful approach for the management of obesity and metabolic conditions. In addition, we will explore some of the mechanisms that may contribute to microbiota-induced susceptibility to obesity and metabolic diseases. PMID:23018760

  6. [Susceptibility of clinically-isolated bacteria strains to respiratory quinolones and evaluation of antimicrobial agent efficacy by Monte Carlo simulation].

    PubMed

    Kosaka, Tadashi; Yamada, Yukiji; Kimura, Takeshi; Kodama, Mai; Fujitomo, Yumiko; Masaki, Nakanishi; Toshiaki, Komori; Keisuke, Shikata; Fujita, Naohisa

    2016-02-01

    Respiratory quinolones (RQs) are broad-spectrum antimicrobial agents used for the treatment of a wide variety of community-acquired and nosocomial infections. However, bacterial resistance to quinolones has been on the increase. In this study, we investigated the predicted efficacy of RQs for various strains of 9 bacterial species clinically isolated at our university hospital using the Monte Carlo simulation (MCS) method based on pharmacokinetics/pharmacodynamics modeling. In addition, the influence of the patients' renal function on the efficacy of RQs was evaluated. We surveyed antimicrobial susceptibility testing of 9 bacterial species (n = number of strains) [Streptococcus pneumoniae (n = 15), Streptococcus pyogenes (n = 14), Streptococcus agalactiae (n = 19), methicillin-susceptible Staphylococcus aureus (MSSA) (n = 24), Escherichia coli (n = 35), Haemophilus influenzae (n = 17), Klebsiella pneumoniae (n = 14), Pseudomonas aeruginosa (n = 31), and Moraxella catarrhalis (n = 11)] to 4 RQs [garenoxacin (GRNX), levofloxacin (LVFX), sitafloxacin (STFX), and moxifloxacin (MFLX)]. We found that compared with the other RQs, Gram-positive cocci was most resistant to LVFX, and that the minimum inhibitory concentration (MIC₉₀) values for S. pneumoniae, S. pyogenes, S. agalactiae, and MSSA were high (2, 16, > 16, and 8 µg/mL, respectively). In regard to Gram-negative rods, the susceptibility of E. coli to RQs was found to be decreased, with the MIC₉₀ values of GRNX, LVFX, STFX, and MFLX being > 16, 16, 1, and 16 µg/mL, respectively. MCS revealed that the target attainment rate of the area under the unbound concentration-time curve divided by the MIC₉₀ (ƒ · AUC/MIC ratio), against S. pneumoniae was 86.9-100%, but against E. coli was low (52.1-66.2%). The ƒ · AUC/MIC target attainment rate of LVFX against S. pneumoniae, S. pyogenes, and S. agalactiae tended to decrease due to increased creatinine clearance, and that of LVFX and STFX against MSSA also

  7. Antimicrobial susceptibility and molecular typing of methicillin-resistant staphylococcus aureus in retail foods in Shaanxi, China.

    PubMed

    Wang, Xin; Li, Guanghui; Xia, Xiaodong; Yang, Baowei; Xi, Meili; Meng, Jianghong

    2014-04-01

    The aims of this study were to evaluate the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in retail foods in Shaanxi, China and to investigate antimicrobial resistance and molecular characteristics of these strains. A total of 1979 retail food samples were randomly collected during 2008-2012 from supermarkets and farmers markets and screened for S. aureus, and then S. aureus isolates were further examined to determine whether they were MRSA. MRSA isolates were further characterized by antimicrobial susceptibility test, pulsed-field gel electrophoresis, spa typing, multilocus sequence typing, and SCCmec typing, and were examined for genes encoding enterotoxins, exfoliative toxins, Panton-Valentine leukocidin (pvl), and toxic shock syndrome toxin 1. Among all the samples examined, four (1.4%) raw milk samples, six (2.3%) chicken samples, one (0.6%) pork sample, three (0.6%) ready-to-eat food samples, and three (2.5%) dumpling samples were positive for MRSA. No MRSA isolates were recovered from infant foods. A total of 23 MRSA isolates were recovered from the 17 MRSA-positive samples. Antimicrobial susceptibility tests showed that, among these MRSA isolates, resistance was most frequently observed to penicillin, ampicillin, oxacillin, cefoxitin, and clindamycin (each 100%), followed by erythromycin (95.7%) and clarithromycin (87.0%). The commonly detected toxin genes were pvl, seg, seb, sed, followed by see, sec, and sei. Seven spa types (t189, t377, t437, t899, t10793, t5762, and a new spa type) and three SCCmec types (II, IVb, and V) were identified. More than half (52.2%) of the MRSA isolates belonged to ST9, followed by ST88, ST59, ST188, ST72, and ST630. Our findings indicate that MRSA in food could be from both animal and human origin. Although the prevalence is low, the presence of multidrug resistant and enterotoxigenic MRSA strains in foods poses a potential threat to consumers and emphasizes the need for better control of sources of

  8. A liaR deletion restores susceptibility to daptomycin and antimicrobial peptides in multidrug-resistant Enterococcus faecalis.

    PubMed

    Reyes, Jinnethe; Panesso, Diana; Tran, Truc T; Mishra, Nagendra N; Cruz, Melissa R; Munita, Jose M; Singh, Kavindra V; Yeaman, Michael R; Murray, Barbara E; Shamoo, Yousif; Garsin, Danielle; Bayer, Arnold S; Arias, Cesar A

    2015-04-15

    Daptomycin is a lipopeptide antibiotic that is used clinically against many gram-positive bacterial pathogens and is considered a key frontline bactericidal antibiotic to treat multidrug-resistant enterococci. Emergence of daptomycin resistance during therapy of serious enterococcal infections is a major clinical issue. In this work, we show that deletion of the gene encoding the response regulator, LiaR (a member of the LiaFSR system that controls cell envelope homeostasis), from daptomycin-resistant Enterococcus faecalis not only reversed resistance to 2 clinically available cell membrane-targeting antimicrobials (daptomycin and telavancin), but also resulted in hypersusceptibility to these antibiotics and to a variety of antimicrobial peptides of diverse origin and with different mechanisms of action. The changes in susceptibility to these antibiotics and antimicrobial peptides correlated with in vivo attenuation in a Caenorhabditis elegans model. Mechanistically, deletion of liaR altered the localization of cardiolipin microdomains in the cell membrane. Our findings suggest that LiaR is a master regulator of the enterococcal cell membrane response to diverse antimicrobial agents and peptides; as such, LiaR represents a novel target to restore the activity of clinically useful antimicrobials against these organisms and, potentially, increase susceptibility to endogenous antimicrobial peptides. PMID:25362197

  9. The species of viridans streptococci associated with microbial endocarditis: incidence and antimicrobial susceptibility.

    PubMed Central

    Roberts, R. B.; Krieger, A. G.; Gross, K. C.

    1978-01-01

    Streptococcal endocarditis has been well recognized for decades and over the years investigators at The New York Hospital have defined many of the diagnostic and therapeutic modalities currently employed in patients with this disease. In this study, speciation of the viridans streptococci has provided new insights into the relative frequency and antimicrobial susceptibility patterns of these organisms. Indeed, recent studies also suggest that S. milleri endocarditis is associated with a high incidence of suppurative complications and that patients with S. bovis endocarditis may have a significant incidence of underlying but asymptomatic lower gastrointestinal malignancies. Further studies correlating viridans streptococcal species with other clinical and laboratory parameters of endocarditis should provide additional insights into this disease. PMID:617021

  10. Desulfovibrio legallii Prosthetic Shoulder Joint Infection and Review of Antimicrobial Susceptibility and Clinical Characteristics of Desulfovibrio Infections

    PubMed Central

    Mason, Erin L.; Gustafson, Daniel R.; Cunningham, Scott A.; Cole, Nicolynn C.; Vetter, Emily A.; Steinmann, Scott P.; Wilson, Walter R.; Patel, Robin; Berbari, Elie F.

    2014-01-01

    We describe a case of shoulder hemiarthroplasty infection with Desulfovibrio legallii. Antimicrobial susceptibilities of 36 Desulfovibrio isolates are presented. Metronidazole and carbapenems exhibited reliable activity, although piperacillin-tazobactam did not. Eleven previous cases of Desulfovibrio infection are reviewed; most arose from a gastrointestinal tract-related source. PMID:24850351

  11. Recommendation for a Standardised Method of Broth Microdilution Susceptibility Testing for Porcine Bordetella bronchiseptica

    PubMed Central

    Prüller, Sandra; Frömke, Cornelia; Kaspar, Heike; Klein, Günter; Kreienbrock, Lothar; Kehrenberg, Corinna

    2015-01-01

    The objective was to establish and standardise a broth microdilution susceptibility testing method for porcine Bordetella (B.) bronchiseptica. B. bronchiseptica isolates from different geographical regions and farms were genotyped by macrorestriction analysis and subsequent pulsed-field gel electrophoresis. One reference and one type strain plus two field isolates of B. bronchiseptica were chosen to analyse growth curves in four different media: cation-adjusted Mueller-Hinton broth (CAMHB) with and without 2% lysed horse blood, Brain-Heart-Infusion (BHI), and Caso broth. The growth rate of each test strain in each medium was determined by culture enumeration and the suitability of CAMHB was confirmed by comparative statistical analysis. Thereafter, reference and type strain and eight epidemiologically unrelated field isolates of B. bronchiseptica were used to test the suitability of a broth microdilution susceptibility testing method following CLSI-approved performance standards given in document VET01-A4. Susceptibility tests, using 20 antimicrobial agents, were performed in five replicates, and data were collected after 20 and 24 hours incubation and statistically analysed. Due to the low growth rate of B. bronchiseptica, an incubation time of 24 hours resulted in significantly more homogeneous minimum inhibitory concentrations after five replications compared to a 20-hour incubation. An interlaboratory comparison trial including susceptibility testing of 24 antimicrobial agents revealed a high mean level of reproducibility (97.9%) of the modified method. Hence, in a harmonization for broth microdilution susceptibility testing of B. bronchiseptica, an incubation time of 24 hours in CAMHB medium with an incubation temperature of 35°C and an inoculum concentration of approximately 5 x 105 cfu/ml was proposed. PMID:25910232

  12. Bacterial bloodstream infections and antimicrobial susceptibility pattern in pediatric hematology/oncology patients after anticancer chemotherapy

    PubMed Central

    Al-Mulla, Naima A; Taj-Aldeen, Saad J; El Shafie, Sittana; Janahi, Mohammed; Al-Nasser, Abdullah A; Chandra, Prem

    2014-01-01

    Purpose Bloodstream infections in pediatric hematology and oncology represent a major problem worldwide, but this has not been studied in Qatar. In this study, we investigated the burden of infection and the resistance pattern in the bacterial etiology, in the only tertiary pediatric hematology and oncology center in Qatar. Methods All pediatric cancer patients (n=185) were evaluated retrospectively during the period 2004–2011; a total of 70 (38%) patients were diagnosed with bloodstream infections. Bacterial etiology was determined, along with their susceptibility patterns. Neutropenia, duration of neutropenia, fever, duration of fever, and C-reactive protein (CRP) were evaluated throughout the study. Results A total of 70 patients (38%) were diagnosed with acute leukemias, lymphomas, solid tumors, or brain tumors; those patients experienced 111 episodes of bacteremia. The most common Gram-positive (n=64 [55%]) isolates were Staphylococcus epidermidis (n=26), Staphylococcus hominis (n=9), and Staphylococcus haemolyticus (n=7), and the common Gram-negative (n=52 [45%]) isolates were Klebsiella pneumoniae (n=14), Pseudomonas aeruginosa (n=10), and Escherichia coli (n=7). There was a significant association observed between fever with positive blood culture and different types of cancer (P=0.035). The majority of bacteremia (n=68 [61.3%]) occurred in nonneutropenic episodes. Elevated values of CRP (≥5 mg/L) were detected in 82 (95.3%) episodes and were negatively correlated with absolute neutrophil count (ANC) (r=−0.18; P=0.248) among all cases. However, the infection-related fatality rate was 2.2% (n=4), with three caused by Gram-negative pathogens. Multidrug resistant organisms were implicated in 33 (28.4%) cases and caused three of the mortality cases. Conclusion Multidrug resistant organisms cause mortality in pediatric cancer patients. Investigation of antimicrobial susceptibility of these organisms may guide successful antimicrobial therapy and improve

  13. The detection and antimicrobial susceptibility profile of Shigella isolates from meat and swab samples at butchers' shops in Gondar town, Northwest Ethiopia.

    PubMed

    Garedew, Legesse; Hagos, Zenabu; Zegeye, Bidir; Addis, Zelalem

    2016-01-01

    Food borne pathogens are major causes of deaths, illnesses and billions of dollars of expenses. The burden of food borne illness is worsened by the ever increasing rate of antimicrobial resistance microbes. Shigella, a bacterial pathogen associated with food, is reported to account for higher prevalence rates of food borne illness in different settings. A cross-sectional study was conducted from February 10 to June 30, 2013, at the butcher houses of Gondar town in the Northwest of Ethiopia to assess the prevalence and antimicrobial susceptibility pattern of Shigella. Cattle raw meat and swab samples from selected critical control points, including knives, chopping boards, and the hands and noses of butchers, were collected and analyzed. The identification of Shigella was carried out using colony characteristics, the Gram reaction, and biochemical tests. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method. The overall hygienic status of the butcher shops was also assessed using a checklist. An observational analysis revealed that the sanitary condition of the butcher shops and their premises was poor. Of 306 samples screened, 10.5% were positive for Shigella. Approximately 7.4% of meat samples and 10.2% of swab samples were contaminated with Shigella. Out of the total Shigella isolates, 90.6%, 46.9%, 18.8% and 9.4% were resistant to ampicillin, amoxicillin, ceftriaxone and tetracycline, respectively. A multidrug resistance pattern was recorded in 27.8% of the isolates. In conclusion, the safety of meat sold at Gondar butchers houses was poor. The identified Shigella isolates showed high levels of drug resistance and multidrug resistance patterns for commonly used antimicrobials in veterinary and human medicine. Practicing wise use of antimicrobials and strict sanitary interventions at different critical control points is strongly recommended, in addition to further in-depth studies to prevent unprecedented consequences from

  14. Short communication: In vitro antimicrobial susceptibility of Mycoplasma bovis isolates identified in milk from dairy cattle in Belgium, Germany, and Italy.

    PubMed

    Barberio, A; Flaminio, B; De Vliegher, S; Supré, K; Kromker, V; Garbarino, C; Arrigoni, N; Zanardi, G; Bertocchi, L; Gobbo, F; Catania, S; Moroni, P

    2016-08-01

    The objective of this study was to assess the in vitro antimicrobial susceptibility of 73 isolates of Mycoplasma bovis isolated from milk of dairy cattle herds of Belgium, Germany, and Italy. Minimal inhibitory concentration (MIC) values were determined by the microbroth dilution method for the following antimicrobials: erythromycin, spiramycin, tilmicosin, tylosin, lincomycin, enrofloxacin, doxycycline, oxytetracycline, florfenicol, and tiamulin. Macrolides, florfenicol, oxytetracycline, and enrofloxacin, were chosen because they represent antimicrobials families commonly used in several countries for treatment of M. bovis, and their MIC values in cattle population are reported in several studies, allowing a comparison with previous data. Doxycycline and tiamulin were selected to assess the susceptibility of M. bovis to new antimicrobials, because they are not registered in the European Union for the treatment of dairy cattle. Among the agents of the different antimicrobial classes, the macrolides showed the highest concentration to inhibit 90% of isolates (MIC90), all above the highest concentration tested: >8μg/mL for erythromycin, >16μg/mL for spiramycin, and >32μg/mL for tilmicosin and tylosin. Also the MIC90 of lincomycin was above the highest concentration tested (>32μg/mL), but the distribution of the MIC values was almost perfectly bimodal: 41 isolates had a MIC ≤0.5μg/mL and 30 isolates >32μg/mL. Oxytetracycline had a 2-fold higher concentration to inhibit 50% of isolates (2 vs. 0.5μg/mL) and 1-fold higher MIC90 (4 vs. 2μg/mL) than doxycycline. Enrofloxacin and florfenicol had both a MIC90 of 2μg/mL, whereas tiamulin had a MIC90 of 0.5μg/mL. Significant differences on the MIC values were found among the 3 countries for several antimicrobials: compared with Germany, Belgium and Italy showed significantly higher MIC for lincomycin, spiramycin, and tylosin, and lower for oxytetracycline and florfenicol. The Belgian isolates showed the lowest MIC

  15. Antimicrobial Susceptibility of Vibrio vulnificus and Vibrio parahaemolyticus Recovered from Recreational and Commercial Areas of Chesapeake Bay and Maryland Coastal Bays

    PubMed Central

    Shaw, Kristi S.; Rosenberg Goldstein, Rachel E.; He, Xin; Jacobs, John M.; Crump, Byron C.; Sapkota, Amy R.

    2014-01-01

    Vibrio vulnificus and V. parahaemolyticus in the estuarine-marine environment are of human health significance and may be increasing in pathogenicity and abundance. Vibrio illness originating from dermal contact with Vibrio laden waters or through ingestion of seafood originating from such waters can cause deleterious health effects, particularly if the strains involved are resistant to clinically important antibiotics. The purpose of this study was to evaluate antimicrobial susceptibility among these pathogens. Surface-water samples were collected from three sites of recreational and commercial importance from July to September 2009. Samples were plated onto species-specific media and resulting V. vulnificus and V. parahaemolyticus strains were confirmed using polymerase chain reaction assays and tested for antimicrobial susceptibility using the Sensititre® microbroth dilution system. Descriptive statistics, Friedman two-way Analysis of Variance (ANOVA) and Kruskal-Wallis one-way ANOVA were used to analyze the data. Vibrio vulnificus (n = 120) and V. parahaemolyticus (n = 77) were isolated from all sampling sites. Most isolates were susceptible to antibiotics recommended for treating Vibrio infections, although the majority of isolates expressed intermediate resistance to chloramphenicol (78% of V. vulnificus, 96% of V. parahaemolyticus). Vibrio parahaemolyticus also demonstrated resistance to penicillin (68%). Sampling location or month did not significantly impact V. parahaemolyticus resistance patterns, but V. vulnificus isolates from St. Martin's River had lower overall intermediate resistance than that of the other two sampling sites during the month of July (p = 0.0166). Antibiotics recommended to treat adult Vibrio infections were effective in suppressing bacterial growth, while some antibiotics recommended for pediatric treatment were not effective against some of the recovered isolates. To our knowledge, these are the first antimicrobial

  16. Antimicrobial susceptibility patterns of clinical Escherichia coli isolates from dogs and cats in the United States: January 2008 through January 2013.

    PubMed

    Thungrat, Kamoltip; Price, Stuart B; Carpenter, D Mark; Boothe, Dawn Merton

    2015-09-30

    Escherichia coli is among the most common bacterial pathogens in dogs and cats. The lack of a national monitoring program limits evidence-based empirical antimicrobial choices in the United States. This study describes antimicrobial susceptibility patterns for presumed clinical E. coli isolates from dogs (n=2392) or cats (n=780) collected from six geographic regions in the United States between May 2008 and January 2013. Minimum inhibitory concentrations (MIC) were determined for 17 drugs representing 6 drug classes. Urinary tract isolates were most common (71%). Population MIC distributions were generally bimodal with the second mode above the resistant breakpoint for all drugs except gentamicin, amikacin, and meropenem. The MIC90 exceeded the susceptible breakpoint for ampicillin, amoxicillin-clavulanic acid, cephalothin (surrogate drug for cephalexin), and doxycycline but was below the susceptible breakpoint for all others. None of isolates was susceptible or resistant to all drug tested; 46% were resistant to 1 or 2 antimicrobial categories, and 52% to more than three categories. The resistance percentages were as follows: doxycycline (100%), cephalothin (98%)>ampicillin (48%)>amoxicillin-clavulanic acid (40%)>ticarcillin-clavulanic acid (18%)>cefpodoxime (13%), cefotaxime (12%), cefoxitin (11%), cefazolin (11%), enrofloxacin (10%), chloramphenicol (9.6%)>ciprofloxacin (9.2%), ceftazidime (8.7%), trimethoprim-sulfamethoxazole (7.9%), gentamicin (7.9%)>meropenem (1.5%), amikacin (0.7%) (P<0.05). Resistance to ampicillin and amoxicillin-clavulanic acid was greatest in the South-Central region (P<0.05). E. coli resistance may preclude empirical treatment with doxycycline, cephalexin, ampicillin, or amoxicillin-clavulanic acid. Based on susceptibility patterns, trimethoprim-sulfonamides may be the preferred empirical oral treatment. PMID:26165272

  17. Frequency, microbial interactions, and antimicrobial susceptibility of Fusobacterium nucleatum and Fusobacterium necrophorum isolated from primary endodontic infections.

    PubMed

    Jacinto, Rogério C; Montagner, Francisco; Signoretti, Fernanda G C; Almeida, Geovania C; Gomes, Brenda P F A

    2008-12-01

    This study assessed the prevalence and microbial interactions of Fusobacterium nucleatum and Fusobacterium necrophorum in primary endodontic infections from a Brazilian population and their antimicrobial susceptibility to some antibiotics by the E-test. One hundred ten samples from infected teeth with periapical pathologies were analyzed by culture methods. Five hundred eighty individual strains were isolated; 81.4% were strict anaerobes. F. nucleatum was found in 38 root canals and was associated with Porphyromonas gingivalis, Prevotella spp., and Eubacterium spp. F. necrophorum was found in 20 root canals and was associated with Peptostreptococcus prevotii. The simultaneous presence of F. nucleatum and F. necrophorum was not related to endodontic symptoms (p > 0.05). They were 100% susceptible to amoxicillin, amoxicillin/clavulanate, and cephaclor. Fusobacterium spp. is frequently isolated from primary-infected root canals of teeth with periapical pathologies. Amoxicillin is a useful antibiotic against F. nucleatum and F. necrophorum in endodontic infections and has been prescribed as the first choice in Brazil. PMID:19026872

  18. [Identification, quantification and antimicrobial susceptibility pattern of probiotic bacteria added to common use food products in Costa Rica].

    PubMed

    Córdoba, Manuela; Chaves, Carolina; Arias, María Laura

    2009-06-01

    In the last years, due to the high demand of food products supplemented with probiotics and the multiple nutritional and therapeutic benefits associated with them, research on these microorganisms has advanced considerably, including their selection and characterization. As a general recommendation, several entities as World Health Organization (WHO) and United Nations Organization for Agriculture and Food recommend that the specification of the alive species contained and their number shall appear in the label of the product. In the present study, six different commercially available products, supplemented with probiotics were analyzed, in order to evaluate the concentration of microorganisms through the shelf life of the product, identify the strains isolated and determine the antibiotic susceptibility pattern of these. Results demonstrated that the strains isolated kept acceptable concentrations during the 28 days of storage. Nevertheless, the identification of these strains variated from the one reported on the label on several of the products tested. This can be due to the commercial method used for the identifications, which is based in the carbohydrate fermentation pattern and not in genotypic trials. The antimicrobials' susceptibility patterns found show that further research shall be performed in order to establish the intrinsic or acquired nature of the resistance determinants, and if these are codified by transferable elements among bacteria. PMID:19719015

  19. Bacterial profile and antimicrobial susceptibility patterns of otitis media in Ayder Teaching and Referral Hospital, Mekelle University, Northern Ethiopia.

    PubMed

    Wasihun, Araya Gebereyesus; Zemene, Yilikal

    2015-01-01

    Middle Ear infection is a common problem for both children and adults particularly in resource limited countries. Nevertheless, in Ethiopia and particularly in the study area, there is scarcity of recent data that indicate the magnitude of the problem. Thus this study aimed to identify bacterial isolates and determine their drug susceptibility patterns from patients who had ear infection. Cross sectional study was carried out on patients with ear infection and who visited the Ear, Nose and Throat clinic of Ayder referral and teaching hospital from November 2014 to June 2015. Middle ear discharges were collected and processed for bacterial culture and antimicrobial susceptibility testing using standard bacteriological techniques. Clinical and demographic data were collected using standard questionnaire. Data were entered and analyzed using SPSS version 20 software and p value of < 0.05 was considered statistically significant. Of the total of 162 patients with ear discharges, 68.5 % were from rural areas, 71 % with chronic infection, 54.9 % referred cases and 67.3 % of them had decreased hearing status. Pathogens were isolated from 157 (98.2 %) of the patients with a total of 216 isolates. Staphylococcus aureus 46 (28.4 %), Proteus mirabilis 39 (24.1 %), Pseudomonas aeruginosa 27 (16.7 %), Klebsiella spp. and Haemophilus influenzae 18 (11.1 % each) were the dominant bacteria. Out of the individuals with ear infection, single and mixed bacterial infection was seen among 185 (90.7 %) and 59 (39.5 %) respectively. Age group of 0-5 years (p = 0.02), chronic patients (p = 0.042) and referred cases (p = 0.045) showed high bacterial isolates. High resistance was seen to most antibiotics. Ciprofloxacin, Gentamicin Norfloxacin and Erythromycin were effective against isolated bacteria. The overall multi drug resistance rate of bacteria in this study was 74.5 %. Prevalence of bacteria associated with otitis media and multidrug resistance was very high in

  20. [Antimicrobial Susceptibility and Resistance Mutations in Campylobacter jejuni and C. coli Isolates from Human and Meat Sources].

    PubMed

    Oishi, Akira; Murakami, Koichi; Etoh, Yoshiki; Sera, Nobuyuki; Horikawa, Kazumi

    2015-03-01

    Recently, there has been a marked increase in the number of reports of fluoroquinolone-resistant Campylobacter jejuni and Campylobacter coli. The aim of this study was to evaluate the prevalence of antimicrobial resistance and its genetic determinants in Campylobacter species isolated from meat and human subjects in Fukuoka Prefecture, Japan. Between 2011 and 2013, 55 and 64 isolates were collected from meat (chicken meat and beef liver) and humans, respectively, in this prefecture. Antimicrobial susceptibility tests were conducted using the agar dilution method in accordance with the Clinical and Laboratory Standards Institute guidelines, using the following 11 antimicrobial agents : cephalexin, cefoxitin, nalidixic acid, ciprofloxacin, levofloxacin, tetracycline, minocycline, ampicillin, streptomycin, kanamycin and erythromycin. The susceptibility rates of the isolates to three quinolones (nalidixic acid, ciprofloxacin, levofloxacin) were 43.7%, 41.2%, 40.3%, respectively. All the isolates were multidrug resistant. Whereas 46.9%-51.6% of the human isolates were resistant to one or more of the quinolones, only 32.7%-34.5% of the meat isolates were resistant to one or more of the drugs. DNA sequencing showed that of the 50 quinolone resistant isolates 44 had position 86 isoleucine (Ile) substituted for threonine (Thr) in the GyrA protein (Thr86Ile). This amino acid substitution resulted from ACA to ATA and ACT to ATT mutations of codon 86 in C. jejuni and C. coli, respectively. Furthermore, two of the four C. jejuni isolates lacking the Thr86Ile mutation had combined Ser22Gly-Asn203Ser substitutions, while the remaining two isolates had combined Ser22Gly-Asn203Ser-Ala 206Val substitutions. These four isolates also had cmeABC sequences that differed from the quinolone sensitive C. jejuni ATCC33560(T) strain. In conclusion, C. jejuni and C. coli have relatively high quinolone resistance, and are resistant to other antibiotics. The new combination of amino acid

  1. Distribution and antimicrobial susceptibility of bacteria from adults with community-acquired pneumonia or complicated skin and soft tissue infections in France: the nationwide French PREMIUM study.

    PubMed

    Leprince, C; Desroches, M; Emirian, A; Coutureau, C; Anais, L; Fihman, V; Soussy, C J; Decousser, J W

    2015-10-01

    The empirical therapy of community-acquired pneumonia (CAP) and complicated skin and soft tissue infections (cSSTIs) must be based on updated bacterial distribution and susceptibility data. A nationwide study consecutively collected 1288 isolates from CAP (n=467) and cSSTIs (n=821) from 18 French hospitals between 2012 and 2013. The MIC values of commonly used antimicrobial agents, including ceftaroline, were determined. Bacterial distribution featured Pneumococcus, Haemophilus influenzae, and Staphylococcus aureus for CAPs and S. aureus, β-hemolytic streptococci and Enterobacteriaceae for cSSTIs. Antimicrobial susceptibility testing indicated i) the sustained third-generation cephalosporins and levofloxacin activity against pneumococci and H. influenzae, ii) no methicillin-resistant Staphylococcus aureus emergence among respiratory pathogens, iii) the high in vitro activity of ceftaroline against staphylococci from cSSTIs (98.7% susceptibility), and iv) the worrisome decreasing fluoroquinolone and third-generation cephalosporin susceptibilities among Enterobacteriaceae. This laboratory-based survey depicts a contrasting situation and supports the scoring of patients for the resistant pathogen risk before empirical therapy. PMID:26166208

  2. [Comparison of antimicrobial use density (AUD) of carbapenem antibacterial agents and investigation of the drug susceptibility of Pseudomonas aeruginosa in 3 hospitals in southern Ibaraki Prefecture, Japan].

    PubMed

    Oishi, Tsuyoshi; Hitomi, Shigemi; Kamoshita, Masaharu; Fukue, Hidetaka; Kawahata, Daisuke; Fukutake, Katsuyuki

    2008-07-01

    The optimal use of anti-Pseudomonas agents is an important issue in the prevention of a tolerance against Pseudomonas aeruginosa. We evaluated the effect of antimicrobial use density (AUD) of carbapenem on drug susceptibility. The AUD of the four carbapenems, imipenem (IPM/CS), panipenem (PAPM/BP), meropenem (MEPM), and biapenem (BIPM), was examined at three hospitals in Ibaraki Prefecture, between April and September 2004. The AUD was calculated using the Defined Daily Doses (DDD) methodology developed by the WHO. A drug susceptibility test was conducted on the 306 Pseudomonas aeruginosa strains randomly collected from clinical specimens at the three hospitals between September and December 2004. In accordance with the standards set by the Clinical and Laboratory Standards Institute (CLSI), minimal inhibitory concentration (MIC) was measured using the broth microdilution method. The results showed that the AUD of carbapenem at the three hospitals tended to be higher than that in other research results in Japan. At one of the three hospitals, the AUD of the PAPM was remarkably high compared to the other carbapenems. Furthermore, P. aeruginosa strains collected at this hospital showed a low susceptibility to carbapenem, and many highly tolerant strains were also observed in this hospital. In order to maintain the susceptibility of Pseudomonas aeruginosa to carbapenem, the overall extent of carbapenem use must be optimal. The use of antimicrobial drugs should be controlled properly at each hospital, in order to prevent excessive use of PAPM/BP from being used over a long period of time. PMID:18709988

  3. Insect Gut Symbiont Susceptibility to Host Antimicrobial Peptides Caused by Alteration of the Bacterial Cell Envelope*

    PubMed Central

    Kim, Jiyeun Kate; Son, Dae Woo; Kim, Chan-Hee; Cho, Jae Hyun; Marchetti, Roberta; Silipo, Alba; Sturiale, Luisa; Park, Ha Young; Huh, Ye Rang; Nakayama, Hiroshi; Fukatsu, Takema; Molinaro, Antonio; Lee, Bok Luel

    2015-01-01

    The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis. PMID:26116716

  4. Combining microdilution with MicroResp™: microbial substrate utilization, antimicrobial susceptibility and respiration.

    PubMed

    Drage, Sigrid; Engelmeier, Doris; Bachmann, Gert; Sessitsch, Angela; Mitter, Birgit; Hadacek, Franz

    2012-03-01

    Pharmacological studies focus on susceptibility of pathogenic microbes against specific drugs or combinations of them, ecological studies on substrate utilization efficiency of variable microbial communities. The MicroResp™ system was especially developed to study soil microbial communities. It was slightly modified to facilitate exploring of microbial growth efficiency in a concentration-dependent fashion (microdilutions of carbohydrate mixtures or specific toxic chemicals). After turbidimetric growth assessment, colorimetric indicator plates (cresol red agar) were mounted to the assay plates. The substrate utilisation design is illustrated by glucose and a plant carbohydrate mixture, the antimicrobial susceptibility design by the naphthoquinone juglone. Dose-response effects are explored by curve fitting of nonlinear models that especially have been developed to detect hormetic effects that are characterized by stimulation at lower followed by inhibition at higher dosages (U- and inverse U-shaped effects). Multivariate analyses are presented utilizing metavariables that were obtained in the curve fitting process of the measured parameters growth and respiration and the factor growth efficiency. PMID:22265657

  5. A comparison of antimicrobial susceptibility profile of urinary pathogens for the years, 1999 and 2003.

    PubMed

    Orrett, F A; Davis, G K

    2006-03-01

    Urinary tract infection is a common condition worldwide; responsible for significant morbidity in both hospitalized and community patients. The laboratory records, for microbial isolates of infected urine and their susceptibility profiles for the years 1999 and 2003 were retrospectively reviewed and compared. In 2003, there was a significant decline in recovery ofCitrobacter spp compared to 1999. Conversely, the proportion of K pneumoniae, E coli and Enterococci increased dramatically in 2003, in both practices. For Proteus vulgaris and Proteus mirabilis, rates of isolation were increased in 2003, in hospital practice and community practice, respectively. Significant changes in antimicrobial susceptibility were also evident. A greater proportion of isolates from both practices were resistant to ampicillin, amoxicillin-clavulanic acid, cefuroxime, ceftazidime and cotrimoxazole in 2003 when compared to 1999. With respect to E coli, there were significant increases in prevalence of resistance to cefuroxime and amoxicillin-clavulanic acid. The overall resistance rate for norfloxacin remained relatively low and was unchanged for E coli. Continued surveillance of uropathogen resistance trends is important and this information should be communicated to clinicians. The feasibility of using the fluoroquinolones as a first line of therapy in urinary tract infection should be considered. PMID:16921702

  6. Use of in vitro vancomycin testing results to predict susceptibility to oritavancin, a new long-acting lipoglycopeptide.

    PubMed

    Jones, Ronald N; Turnidge, John D; Moeck, Greg; Arhin, Francis F; Mendes, Rodrigo E

    2015-04-01

    Oritavancin is a recently approved lipoglycopeptide antimicrobial agent with activity against Gram-positive pathogens. Its extended serum elimination half-life and concentration-dependent killing enable single-dose treatment of acute bacterial skin and skin structure infections. At the time of regulatory approval, new agents, including oritavancin, are not offered in the most widely used susceptibility testing devices and therefore may require application of surrogate testing using a related antimicrobial to infer susceptibility. To evaluate vancomycin as a predictive susceptibility marker for oritavancin, 26,993 recent Gram-positive organisms from U.S. and European hospitals were tested using reference MIC methods. Organisms included Staphylococcus aureus, coagulase-negative staphylococci (CoNS), beta-hemolytic streptococci (BHS), viridans group streptococci (VGS), and enterococci (ENT). These five major pathogen groups were analyzed by comparing results with FDA-approved susceptible breakpoints for both drugs, as well as those suggested by epidemiological cutoff values and supported by pharmacokinetic/pharmacodynamic analyses. Vancomycin susceptibility was highly accurate (98.1 to 100.0%) as a surrogate for oritavancin susceptibility among the indicated pathogen species. Furthermore, direct MIC comparisons showed high oritavancin potencies, with vancomycin/oritavancin MIC90 results of 1/0.06, 2/0.06, 0.5/0.12,1/0.06, and >16/0.06 μg/ml for S. aureus, CoNS, BHS, VGS, and ENT, respectively. In conclusion, vancomycin demonstrated acceptable accuracy as a surrogate marker for predicting oritavancin susceptibility when tested against the indicated pathogens. In contrast, 93.3% of vancomycin-nonsusceptible enterococci had oritavancin MIC values of ≤0.12 μg/ml, indicating a poor predictive value of vancomycin for oritavancin resistance against these organisms. Until commercial oritavancin susceptibility testing devices are readily available, isolates that when

  7. Susceptibility testing of Actinobacillus pleuropneumoniae in Denmark. Evaluation of three different media of MIC-determinations and tablet diffusion tests.

    PubMed

    Aarestrup, F M; Jensen, N E

    1999-02-12

    This study was conducted to compare the applicability of three different media in sensitivity testing of Actinobacillus pleuropneumoniae by means of MIC and tablet diffusion tests. The media used were: modified PPLO agar, chocolatized Mueller-Hinton-II and Columbia agar supplemented with NAD. Seven antimicrobial agents were tested: ceftiofur, enrofloxacin, penicillin, spectinomycin, tiamulin, trimethoprim + sulfadiazine and tylosin, against 40 randomly selected A. pleuropneumoniae isolates. In general, good agreement was found between results obtained with all combinations of media, most antimicrobials tested and the two-test systems. Some variations between media were observed for spectinomycin, tiamulin and tylosin. For ceftiofur and trimethoprim + sulfadiazine some isolates with low MIC-values were classified as resistant using tablet diffusion, indicating that the break points of resistance for these antimicrobials using the tablet diffusion tests need adjustment. Using current break points for resistance with MIC-determinations, all isolates tested susceptible to ceftiofur, enrofloxacin, penicillin, tiamulin and trimethoprim + sulfadiazine. A larger number of isolates tested resistant to spectinomycin and tylosin on all three media using both MIC determinations and tablet diffusion. PMID:10063535

  8. First comprehensive evaluation of the M.I.C. evaluator device compared to Etest and CLSI reference dilution methods for antimicrobial susceptibility testing of clinical strains of anaerobes and other fastidious bacterial species.

    PubMed

    Rennie, R P; Turnbull, L; Brosnikoff, C; Cloke, J

    2012-04-01

    The new M.I.C. Evaluator strip uses test methodology and the recording of results that are similar to those of Etest. For this first assessment, 102 clinical strains of anaerobic bacteria from 12 genera and 155 strains from 7 genera and 8 species of fastidious bacteria were tested by M.I.C. Evaluator, Etest, and agar dilution or broth microdilution as a reference standard. Ampicillin, amoxicillin, amoxicillin-clavulanate, cefotaxime, ciprofloxacin, erythromycin, imipenem, levofloxacin, metronidazole, penicillin, and tetracycline were tested depending on the species. Agar dilution for anaerobes was performed according to CLSI document M11-A7. For the fastidious bacteria, CLSI document M45-A2 was followed. For the anaerobes, essential and categorical agreement between M.I.C. Evaluator and Etest was >90%. Compared to agar dilution, essential agreement was low for both strip tests, and many very major errors were observed for metronidazole (13 to 14%) and penicillin (8 to 9%) with isolates from the Bacteroides fragilis group and Clostridium species. For fastidious species, essential agreements for M.I.C. Evaluator and Etest plus or minus one doubling dilution were >95%. Compared to broth microdilution, essential agreements were low (40 to 90%) plus or minus one dilution and were >90% plus or minus two dilutions, with high overall category agreement (CA). Major and minor errors were within established parameters for all strains tested. The M.I.C. Evaluator strips were equivalent to Etest for anaerobes and fastidious species. These observations require further investigation to determine which methods provide the most accurate MIC for clinical utility. The further evaluation of additional M.I.C. Evaluator agents will be performed as they become available. PMID:22238439

  9. Antimicrobial susceptibilities and molecular epidemiology of clinical isolates of Clostridium difficile in taiwan.

    PubMed

    Lin, Yi-Chun; Huang, Yu-Tsung; Tsai, Pei-Jane; Lee, Tai-Fen; Lee, Nan-Yao; Liao, Chun-Hsing; Lin, Shyr-Yi; Ko, Wen-Chien; Hsueh, Po-Ren

    2011-04-01

    The antimicrobial susceptibility and virulence factors of Clostridium difficile clinical isolates in Taiwan have not previously been reported. One hundred and thirteen isolates were collected from two major teaching hospitals in Taiwan from 2001 to 2009. Molecular typing was performed by an automated repetitive extragenic palindromic sequence-based PCR (rep-PCR) method (DiversiLab; Bacterial Barcodes, Inc., Athens, GA) and PCR ribotyping. Detection of tcdA, tcdB, cdtA, and cdtB genes was performed using a multiplex PCR assay, and gyrA and gyrB genes of moxifloxacin-nonsusceptible isolates were sequenced. All isolates were susceptible to vancomycin and metronidazole. Ninety-five (84%) isolates were susceptible to moxifloxacin, and the MIC(90) for nemonoxacin was 4 μg/ml. Tigecycline showed favorable antibacterial activity (MIC(90) of 0.06 μg/ml). Thirteen rep-PCR types were identified as a predominant rep-PCR type (type A; non-North American pulsed-field gel electrophoresis type 1 [NAP1], -NAP7, or -NAP8) accounting for 52.2% (59 isolates). Nine of 18 moxifloxacin-nonsusceptible isolates belonged to the rep-PCR type A. The rep-PCR type A and C isolates were distinct from NAP1 (ribotype 027) and NAP8 (ribotype 078) as determined by PCR ribotyping. Seventy-four (65%) isolates harbored tcdA and tcdB, and 15 (13%) harbored cdtAB encoding binary toxin. Eleven isolates had a gene deletion in tcdC, including a 39-bp deletion (9 isolates) and an 18-bp deletion (2). In conclusion, dissemination of a predominant C. difficile clone in southern and northern Taiwan was noted. However, no NAP1 (ribotype 027) isolate could be discovered in this study. PMID:21263053

  10. Antimicrobial susceptibility pattern of Edwardsiella ictaluri isolates from natural outbreaks of bacillary necrosis of Pangasianodon hypophthalmus in Vietnam.

    PubMed

    Tu, Thanh Dung; Haesebrouck, Freddy; Nguyen, Anh Tuan; Sorgeloos, Patrick; Baele, Margo; Decostere, Annemie

    2008-12-01

    The purpose of this study was to assess the in vitro susceptibility of 64 Vietnamese isolates of Edwardsiella ictaluri, the causal agent of the infectious disease Bacillus Necrosis Pangasius in Pangasianodon hypophthalmus, using the agar dilution technique. All isolates originated from different farms and were collected between 2002 and 2005. None of the isolates displayed acquired resistance to amoxicillin, amoxicillin-clavulanic acid, chloramphenicol, florfenicol, gentamicin, kanamycin, neomycin, and nitrofurantoin. Acquired resistance to streptomycin was detected in 83%, to oxytetracycline in 81%, and to trimethoprim in 71% of the isolates, as indicated by a bimodal distribution of the minimal inhibitory concentrations (MICs) of these antimicrobials. The MICs of enrofloxacin displayed a monomodal distribution with tailing toward the higher MIC values, possibly indicating reduced susceptibility of a minority of isolates (3 out of the 64). For the quinolone antimicrobial agents flumequin and oxolinic acid, acquired resistance was encountered in 8% and 6% of the strains, respectively. All strains were intrinsically resistant to the polypeptide antimicrobial agent colistin. Seventy-three percent of the isolates were shown to have acquired resistance to at least three antimicrobial agents. The results of this study emphasize the strict need to control both the prophylactic and curative use of antimicrobial agents in Vietnamese aquaculture. PMID:19090723

  11. Phenotypic, antimicrobial susceptibility profile and virulence factors of Klebsiella pneumoniae isolated from buffalo and cow mastitic milk

    PubMed Central

    Osman, Kamelia M; Hassan, Hany M; Orabi, Ahmed; Abdelhafez, Ahmed S T

    2014-01-01

    Studies on the prevalence and virulence genes of Klebsiella mastitis pathogens in a buffalo population are undocumented. Also, the association of rmpA kfu, uge, magA, Aerobactin, K1 and K2 virulent factors with K. pneumoniae buffalo, and cow mastitis is unreported. The virulence of K. pneumoniae was evaluated through both phenotypic and molecular assays. In vivo virulence was assessed by the Vero cell cytotoxicity, suckling mouse assay and mice lethality test. Antimicrobial susceptibility was tested by disk diffusion method. The 45 K. pneumoniae isolates from buffalo (n = 10/232) and cow (n = 35/293) milk were isolated (45/525; 8.6%) and screened via PCR for seven virulence genes encoding uridine diphosphate galactose 4 epimerase encoding gene responsible for capsule and smooth lipopolysaccharide synthesis (uge), siderophores (kfu and aerobactin), protectines or invasins (rmpA and magA), and the capsule and hypermucoviscosity (K1 and K2). The most common virulence genes were rmpA, kfu, uge, and magA (77.8% each). Aerobactin and K1 genes were found at medium rates of 66.7% each and K2 (55.6%). The Vero cell cytotoxicity and LD (50) in mice were found in 100% of isolates. A multidrug resistance pattern was observed for 40% of the antimicrobials. The distribution of virulence profiles indicate a role of rmpA, kfu, uge, magA, Aerobactin, and K1 and K2 in pathogenicity of K. pneumoniae in udder infections and invasiveness, and constitutes a threat for vulnerable animals, even more if they are in combination with antibiotic resistance. PMID:24915048

  12. Molecular Characterization and Antimicrobial Susceptibility of Staphylococcus aureus Isolates from Clinical Infection and Asymptomatic Carriers in Southwest Nigeria

    PubMed Central

    Olasupo, Nurudeen A.; Egwari, Louis O.; Becker, Karsten

    2015-01-01

    Few reports from Africa suggest that resistance pattern, virulence factors and genotypes differ between Staphylococcus aureus from nasal carriage and clinical infection. We therefore compared antimicrobial resistance, selected virulence factors and genotypes of S. aureus from nasal carriage and clinical infection in Southwest Nigeria. Non-duplicate S. aureus isolates were obtained from infection (n = 217) and asymptomatic carriers (n = 73) during a cross sectional study in Lagos and Ogun States, Nigeria from 2010–2011. Susceptibility testing was performed using Vitek automated systems. Selected virulence factors were detected by PCR. The population structure was assessed using spa typing. The spa clonal complexes (spa-CC) were deduced using the Based Upon Repeat Pattern algorithm (BURP). Resistance was higher for aminoglycosides in clinical isolates while resistances to quinolones and tetracycline were more prevalent in carrier isolates. The Panton-Valentine leukocidin (PVL) was more frequently detected in isolates from infection compared to carriage (80.2 vs 53.4%; p<0.001, chi2-test). Seven methicillin resistant S. aureus isolates were associated with spa types t002, t008, t064, t194, t8439, t8440 and t8441. The predominant spa types among the methicillin-susceptible S. aureus isolates were t084 (65.5%), t2304 (4.4%) and t8435 (4.1%). spa-CC 084 was predominant among isolates from infection (80.3%, n = 167) and was significantly associated with PVL (OR = 7.1, 95%CI: 3.9–13.2, p<0.001, chi2- test). In conclusion, PVL positive isolates were more frequently detected among isolates from infection compared to carriage and are associated with spa-CC 084. PMID:26348037

  13. Molecular Characterization and Antimicrobial Susceptibility of Staphylococcus aureus Isolates from Clinical Infection and Asymptomatic Carriers in Southwest Nigeria.

    PubMed

    Ayepola, Olayemi O; Olasupo, Nurudeen A; Egwari, Louis O; Becker, Karsten; Schaumburg, Frieder

    2015-01-01

    Few reports from Africa suggest that resistance pattern, virulence factors and genotypes differ between Staphylococcus aureus from nasal carriage and clinical infection. We therefore compared antimicrobial resistance, selected virulence factors and genotypes of S. aureus from nasal carriage and clinical infection in Southwest Nigeria. Non-duplicate S. aureus isolates were obtained from infection (n = 217) and asymptomatic carriers (n = 73) during a cross sectional study in Lagos and Ogun States, Nigeria from 2010-2011. Susceptibility testing was performed using Vitek automated systems. Selected virulence factors were detected by PCR. The population structure was assessed using spa typing. The spa clonal complexes (spa-CC) were deduced using the Based Upon Repeat Pattern algorithm (BURP). Resistance was higher for aminoglycosides in clinical isolates while resistances to quinolones and tetracycline were more prevalent in carrier isolates. The Panton-Valentine leukocidin (PVL) was more frequently detected in isolates from infection compared to carriage (80.2 vs 53.4%; p<0.001, chi2-test). Seven methicillin resistant S. aureus isolates were associated with spa types t002, t008, t064, t194, t8439, t8440 and t8441. The predominant spa types among the methicillin-susceptible S. aureus isolates were t084 (65.5%), t2304 (4.4%) and t8435 (4.1%). spa-CC 084 was predominant among isolates from infection (80.3%, n = 167) and was significantly associated with PVL (OR = 7.1, 95%CI: 3.9-13.2, p<0.001, chi2-test). In conclusion, PVL positive isolates were more frequently detected among isolates from infection compared to carriage and are associated with spa-CC 084. PMID:26348037

  14. Antimicrobial susceptibility monitoring of mastitis pathogens isolated from acute cases of clinical mastitis in dairy cows across Europe: VetPath results.

    PubMed

    Thomas, Valérie; de Jong, Anno; Moyaert, Hilde; Simjee, Shabbir; El Garch, Farid; Morrissey, Ian; Marion, Hervé; Vallé, Michel

    2015-07-01

    VetPath is an ongoing pan-European antimicrobial susceptibility monitoring programme collecting pathogens from diseased cattle, pigs and poultry not recently treated with antibiotics. Non-replicate milk samples were collected from cows with acute clinical mastitis in eight countries. Escherichia coli, Staphylococcus aureus and Streptococcus uberis were isolated by standardised methods. Antimicrobial susceptibility was determined in a central laboratory by CLSI broth microdilution methodology; results were interpreted using clinical breakpoints where available. Among E. coli (n=280), resistance to tetracycline (14.3%) and cefapirin (11.1%) were most common. Resistance to other β-lactam antibiotics was absent (ceftiofur) or very low (cefalexin, amoxicillin/clavulanic acid). The MIC90 of enrofloxacin and marbofloxacin was 0.03 and 0.06μg/mL, respectively, with 0.7% of strains displaying a deviating high MIC. Staphylococcus aureus (n=250) were susceptible to most antibiotics tested, although 36.0% were resistant to penicillin G. For other β-lactam antibiotics where a CLSI breakpoint was available, no resistance was detected. Tetracycline resistance was low (5.2%). Streptococcus uberis (n=282) were susceptible to all β-lactam antibiotics, although 29.8% were intermediately susceptible to penicillin G; 18.8% of strains were resistant to erythromycin and 28.7% to tetracycline. This European study shows that bacteria associated with acute clinical mastitis are susceptible to most antibiotics with the exception of penicillin G against S. aureus, and erythromycin and tetracycline against S. uberis. The results of this study should serve as a reference baseline. This work also highlights the urgent need to set additional clinical breakpoints for antibiotics frequently used to treat mastitis. PMID:26003836

  15. Reliability of provocative tests of motion sickness susceptibility

    NASA Technical Reports Server (NTRS)

    Calkins, D. S.; Reschke, M. F.; Kennedy, R. S.; Dunlop, W. P.

    1987-01-01

    Test-retest reliability values were derived from motion sickness susceptibility scores obtained from two successive exposures to each of three tests: (1) Coriolis sickness sensitivity test; (2) staircase velocity movement test; and (3) parabolic flight static chair test. The reliability of the three tests ranged from 0.70 to 0.88. Normalizing values from predictors with skewed distributions improved the reliability.

  16. Use of Aeromonas spp. as General Indicators of Antimicrobial Susceptibility among Bacteria in Aquatic Environments in Thailand.

    PubMed

    Usui, Masaru; Tagaki, Chie; Fukuda, Akira; Okubo, Torahiko; Boonla, Chanchai; Suzuki, Satoru; Seki, Kanako; Takada, Hideshige; Tamura, Yutaka

    2016-01-01

    Antimicrobials are widely used, not only for treating human infections, but also for treatment of livestock and in fish farms. Human habitats in Southeastern Asian countries are located in close proximity to aquatic environments. As such, the human populations within these regions are at risk of exposure to antimicrobial resistant bacteria, and thereby disseminating antimicrobial resistance genes (ARGs). In this study, we collected water samples from 15 sites (5 sites in Chao Phraya River, 2 sites at the mouth of Chao Phraya River, 3 sites in Ta Chin River, and 5 sites at city canals) and 12 sites (6 sites at city canals; 2 sites at chicken farms; 2 sites at pig farms; and 2 samples from sites at pig farms, which were subsequently treated at a biogas plant) in Thailand in 2013 and 2014, respectively. In total, 117 Aeromonas spp. were isolated from the water samples, and these organisms exhibited various antimicrobial susceptibility profiles. Notably, there was a significant correlation between the environmental concentration of tetracyclines and the rates of tetracycline resistance in the isolated Aeromonas spp.; however, both the concentration and rates of tetracycline resistance in samples derived from pig farms were higher than those of samples harvested from other aquatic environments. These findings suggest that the high concentrations of antimicrobials observed in these aquatic environments likely select for ARGs. Furthermore, they indicate that Aeromonas spp. comprise an effective marker for monitoring antimicrobial resistance in aquatic environments. PMID:27433156

  17. Use of Aeromonas spp. as General Indicators of Antimicrobial Susceptibility among Bacteria in Aquatic Environments in Thailand

    PubMed Central

    Usui, Masaru; Tagaki, Chie; Fukuda, Akira; Okubo, Torahiko; Boonla, Chanchai; Suzuki, Satoru; Seki, Kanako; Takada, Hideshige; Tamura, Yutaka

    2016-01-01

    Antimicrobials are widely used, not only for treating human infections, but also for treatment of livestock and in fish farms. Human habitats in Southeastern Asian countries are located in close proximity to aquatic environments. As such, the human populations within these regions are at risk of exposure to antimicrobial resistant bacteria, and thereby disseminating antimicrobial resistance genes (ARGs). In this study, we collected water samples from 15 sites (5 sites in Chao Phraya River, 2 sites at the mouth of Chao Phraya River, 3 sites in Ta Chin River, and 5 sites at city canals) and 12 sites (6 sites at city canals; 2 sites at chicken farms; 2 sites at pig farms; and 2 samples from sites at pig farms, which were subsequently treated at a biogas plant) in Thailand in 2013 and 2014, respectively. In total, 117 Aeromonas spp. were isolated from the water samples, and these organisms exhibited various antimicrobial susceptibility profiles. Notably, there was a significant correlation between the environmental concentration of tetracyclines and the rates of tetracycline resistance in the isolated Aeromonas spp.; however, both the concentration and rates of tetracycline resistance in samples derived from pig farms were higher than those of samples harvested from other aquatic environments. These findings suggest that the high concentrations of antimicrobials observed in these aquatic environments likely select for ARGs. Furthermore, they indicate that Aeromonas spp. comprise an effective marker for monitoring antimicrobial resistance in aquatic environments. PMID:27433156

  18. Antimicrobial susceptibility of canine and human Staphylococcus aureus collected in Saskatoon, Canada.

    PubMed

    Rubin, J E; Chirino-Trejo, M

    2011-11-01

    Staphylococcus aureus is one of the most common causes of infection in people and is increasingly recognized in dogs. The increasing prevalence of methicillin resistant S. aureus (MRSA) is complicating the treatment of these infections. Panton Valentine leukocidin (PVL), a toxin involved in the pathogenesis of necrotic syndromes in people may be partially responsible for the rise of MRSA. Canine and human S. aureus from the same geographic area are genetically similar, indicating a common population and likely transmission. The implications of increasing antimicrobial resistance complicated by interspecies transmission, necessitates including both dogs and humans in S. aureus resistance surveillance studies. A collection of 126 S. aureus isolates from people (n = 99) and dogs (n = 27) were included, minimum inhibitor concentrations to a panel of 33 antimicrobials used in human and veterinary medicine were determined. No resistance to vancomycin, linezolid, daptomycin, quinupristin/dalfopristin or nitrofurantoin was found. A wide range of antibiograms were found; including resistance to 0-12 drugs (0-6 drug classes). Outstanding antibiograms included a canine MRSA resistant to rifampin and a human MRSA resistant to chloramphenicol. Inducible clindamycin resistance was found among 78% and 4% of canine and human MRSA and 17% and 25% of canine colonizing and human methicillin susceptible S. aureus (MSSA), respectively. Resistance to mupirocin was only found among human isolates including 20% of MRSA and 4% of MSSA. While no canine isolates were PVL positive, 39% of human MRSA and 2% of MSSA carried the gene. The bidirectional transmission of S. aureus between people and dogs necessitates the inclusion of isolates from both species in future studies. PMID:21824346

  19. Comparison of Antimicrobial Susceptibilities of Pharyngeal, Rectal, and Urethral Neisseria gonorrhoeae Isolates among Men Who Have Sex with Men

    PubMed Central

    Zaidi, Akbar; Asbel, Lenore; Baldwin, Tamara; Gratzer, Beau; Guerry, Sarah; Kerani, Roxanne P.; Pathela, Preeti; Pettus, Kevin; Soge, Olusegun O.; Stirland, Ali; Weinstock, Hillard S.

    2015-01-01

    U.S. surveillance for Neisseria gonorrhoeae antimicrobial susceptibilities is based exclusively on male urethral isolates. These data inform gonorrhea treatment guidelines, including recommendations for the treatment of extragenital infections, but data on the susceptibilities of extragenital isolates are limited. We compared the antimicrobial susceptibilities of pharyngeal, rectal, and urethral gonococcal isolates collected from men who have sex with men (MSM), at five sentinel sites throughout the United States. MICs were determined by the agar dilution method. Generalized linear models were used to compare (i) the proportions of isolates with elevated MICs and (ii) geometric mean MICs according to anatomic site, adjusted for city. In December 2011 to September 2013, totals of 205 pharyngeal, 261 rectal, and 976 urethral isolates were obtained. The proportions of isolates with elevated ceftriaxone MICs (≥0.125 μg/ml) did not differ according to anatomic site (0.5% of pharyngeal isolates, 1.5% of rectal isolates, and 1.7% of urethral isolates, with a city-adjusted odds ratio [aOR] of 0.4 [95% confidence interval {CI}, 0.0 to 3.9] for pharyngeal versus urethral isolates and an aOR of 0.9 [95% CI, 0.2 to 4.2] for rectal versus urethral isolates). The city-adjusted geometric mean ceftriaxone MICs of pharyngeal (0.0153 μg/ml) and rectal (0.0157 μg/ml) isolates did not differ from that of urethral isolates (0.0150 μg/ml) (ratios of geometric mean MICs of 1.02 [95% CI, 0.90 to 1.17] and 1.05 [95% CI, 0.93 to 1.19], respectively). Similar results were observed for other antimicrobials, including cefixime and azithromycin. These findings suggest that, at the population level, gonococcal antimicrobial susceptibility surveillance based on urethral isolates from MSM adequately reflects the susceptibilities of N. gonorrhoeae strains circulating among MSM. PMID:25691638

  20. Comparison of antimicrobial susceptibilities of pharyngeal, rectal, and urethral Neisseria gonorrhoeae isolates among men who have sex with men.

    PubMed

    Kidd, Sarah; Zaidi, Akbar; Asbel, Lenore; Baldwin, Tamara; Gratzer, Beau; Guerry, Sarah; Kerani, Roxanne P; Pathela, Preeti; Pettus, Kevin; Soge, Olusegun O; Stirland, Ali; Weinstock, Hillard S

    2015-05-01

    U.S. surveillance for Neisseria gonorrhoeae antimicrobial susceptibilities is based exclusively on male urethral isolates. These data inform gonorrhea treatment guidelines, including recommendations for the treatment of extragenital infections, but data on the susceptibilities of extragenital isolates are limited. We compared the antimicrobial susceptibilities of pharyngeal, rectal, and urethral gonococcal isolates collected from men who have sex with men (MSM), at five sentinel sites throughout the United States. MICs were determined by the agar dilution method. Generalized linear models were used to compare (i) the proportions of isolates with elevated MICs and (ii) geometric mean MICs according to anatomic site, adjusted for city. In December 2011 to September 2013, totals of 205 pharyngeal, 261 rectal, and 976 urethral isolates were obtained. The proportions of isolates with elevated ceftriaxone MICs (≥ 0.125 μg/ml) did not differ according to anatomic site (0.5% of pharyngeal isolates, 1.5% of rectal isolates, and 1.7% of urethral isolates, with a city-adjusted odds ratio [aOR] of 0.4 [95% confidence interval {CI}, 0.0 to 3.9] for pharyngeal versus urethral isolates and an aOR of 0.9 [95% CI, 0.2 to 4.2] for rectal versus urethral isolates). The city-adjusted geometric mean ceftriaxone MICs of pharyngeal (0.0153 μg/ml) and rectal (0.0157 μg/ml) isolates did not differ from that of urethral isolates (0.0150 μg/ml) (ratios of geometric mean MICs of 1.02 [95% CI, 0.90 to 1.17] and 1.05 [95% CI, 0.93 to 1.19], respectively). Similar results were observed for other antimicrobials, including cefixime and azithromycin. These findings suggest that, at the population level, gonococcal antimicrobial susceptibility surveillance based on urethral isolates from MSM adequately reflects the susceptibilities of N. gonorrhoeae strains circulating among MSM. PMID:25691638

  1. MOLECULAR CHARACTERIZATION OF VIRULENCE AND ANTIMICROBIAL SUSCEPTIBILITY PROFILES OF UROPATHOGENIC ESCHERICHIA COLI FROM PATIENTS IN A TERTIARY HOSPITAL, SOUTHERN THAILAND.

    PubMed

    Themphachanal, Monchanok; Kongpheng, Suttiporn; Rattanachuay, Pattamarat; Khianngam, Saowapar; Singkhamanan, Kamonnut; Sukhumungoon, Pharanai

    2015-11-01

    Among uropathogens, uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infection (UTI) worldwide, but clinical aspects due to this bacterial species is not fully understood in southern Thailand. Two hundred fifty-four UPEC isolates from patients admitted to Maharaj Nakhon Si Thammarat Hospital, southern Thailand were examined for crucial virulence genes, showing that 33.5% contained at least one of the virulence, genes tested. Genes encoding P fimbria, cytotoxic necrotizing factor-1 and α-hemolysin constituted the majority (15.8%) carried by UPEC isolates. Phylogenetic group classification revealed that 57.5% of UPEC belonged to group D. Antimicrobial susceptibility tests showed that 70.5% and 65.1% of the isolates were resistant to ciprofloxacin and norfloxacin, respectively. Moreover, 50.0% of UPEC were capable of producing extended spectrum beta-lactamases. These findings should be of benefit for more appropriate treatment of UTI patients in this region of Thailand. Keywords: uropathogenic Escherichia coli, antibiotics resistance, cnfl, hlyA, pap, Thailand PMID:26867360

  2. Oral colonization and susceptibility testing of Pseudomonas aeruginosa oral isolates from cystic fibrosis patients.

    PubMed

    Lindemann, R A; Newman, M G; Kaufman, A K; Le, T V

    1985-01-01

    Microbial samples from the oral cavities of cystic fibrosis (C.F.) patients and 20 age-matched normal control subjects were characterized. Mucoid variant Pseudomonas aeruginosa was isolated from the tongue, buccal mucosa, and saliva of C.F. patients only. Analysis of the data suggests that the oral cavity is a potential reservoir for this organism. Aspiration and cross-contamination from this reservoir may be important in perpetuating chronic pulmonary infection in C.F. patients. Susceptibility testing was performed on 20 mucoid variant P. aeruginosa oral isolates obtained from the patients according to standardized broth dilution procedures. The in vitro antimicrobial effects of sodium fluoride, stannous fluoride, and chlorhexidine were measured. Analysis of the data suggests that clinically safe and achievable levels of chlorhexidine and stannous fluoride may be antimicrobial. PMID:3918088

  3. Differences in antimicrobial susceptibility breakpoints for Pseudomonas aeruginosa, isolated from blood cultures, set by the Clinical and Laboratory Standards Institute (CLSI) and the Japanese Society of Chemotherapy.

    PubMed

    Nakamura, Tatsuya; Shimizu, Chihiro; Kasahara, Mayumi; Nakata, Chiyo; Munakata, Machiko; Takahashi, Hakuo

    2007-02-01

    A study was made of the antimicrobial susceptibility to and efficacy of various kinds of antimicrobial agents against 179 strains of Pseudomonas aeruginosa that were isolated from blood cultures at Kansai Medical University Hospital from 1990 through 2004. The annual detection rate was highest in 1994, at 22 strains (6.5%). There were 9 multidrug resistant strains of Pseudomonas aeruginosa (5.0%). Among 14 antimicrobial agents tested for measurements, ciprofloxacin (CPFX) showed the best minimum inhibitory concentration (MIC) 50 value, of 0.25 microg/ml, followed by pazufloxacin (PZFX) and biapenem (BIPM), each at 0.5 microg/ml. When the period of 15 years was divided into three stages, the MIC50 value for each antimicrobial agent was highest in the middle stage (1995 to 1999). Assuming that the percentage of sensitive strains according to the breakpoints set by the Clinical and Laboratory Standards Institute (CLSI) represents the antimicrobial susceptibility rate, amikacin (AMK) showed the best value, of 85.5%. According to the sepsis breakpoint set by the Japanese Society of Chemotherapy (JSC), the efficacy of CPFX showed the highest rate (77.1%) of all the antimicrobial agents tested. Among beta-lactams, BIPM showed the highest efficacy rate, of 67.0%. When the efficacy rates were compared with each other, the difference in efficacy rate between the breakpoint set by the CLSI and the sepsis breakpoint set by the JSC was large for beta-lactams. Comparisons made based on the CLSI criteria showed no difference in cross-resistance rates between CPFX, meropenem (MEPM), and BIPM. However, when comparisons were made using the JSC sepsis breakpoint, MEPM showed a cross-resistance rate of 87.8%, while the rate for BIPM was lower, at 56.1%, with the chi2 test showing a significant difference, at P = 0.0014. In accordance with the pharmacokinetics/pharmacodynamics theory that has been advocated, breakpoints which are more suitable for the clinical setting in Japan should

  4. Automatic Radiated Susceptibility Test System for Payload Equipment

    NASA Technical Reports Server (NTRS)

    Ngo, Hoai T.; Sturman, John C.; Sargent, Noel B.

    1995-01-01

    An automatic radiated susceptibility test system (ARSTS) was developed for NASA Lewis Research Center's Electro-magnetic Interference laboratory. According to MSFC-SPEC 521B, any electrical or electronic equipment that will be transported by the spacelab and space shuttle must be tested for susceptibility to electromagnetic interference. This state-of-the-art automatic test system performs necessary calculations; analyzes, processes, and records a great quantity of measured data; and monitors the equipment being tested in real-time and with minimal user intervention. ARSTS reduces costly test time, increases test accuracy, and provides reliable test results.

  5. Automatic radiated susceptibility test system for payload equipment

    NASA Astrophysics Data System (ADS)

    Ngo, Hoai T.; Sturman, John C.; Sargent, Noel B.

    1995-09-01

    An automatic radiated susceptibility test system (ARSTS) was developed for NASA Lewis Research Center's Electro-magnetic Interference laboratory. According to MSFC-SPEC 521B, any electrical or electronic equipment that will be transported by the spacelab and space shuttle must be tested for susceptibility to electromagnetic interference. This state-of-the-art automatic test system performs necessary calculations; analyzes, processes, and records a great quantity of measured data; and monitors the equipment being tested in real-time and with minimal user intervention. ARSTS reduces costly test time, increases test accuracy, and provides reliable test results.

  6. Prevalence and Antimicrobial Susceptibility Patterns of Bacteria from Milkmen and Cows with Clinical Mastitis in and around Kampala, Uganda

    PubMed Central

    Kateete, David Patrick; Kabugo, Usuf; Baluku, Hannington; Nyakarahuka, Luke; Kyobe, Samuel; Okee, Moses; Najjuka, Christine Florence; Joloba, Moses Lutaakome

    2013-01-01

    Background Identification of pathogens associated with bovine mastitis is helpful in treatment and management decisions. However, such data from sub-Saharan Africa is scarce. Here we describe the distribution and antimicrobial susceptibility patterns of bacteria from cows with clinical mastitis in Kampala, Uganda. Due to high concern of zoonotic infections, isolates from milkmen are also described. Methodology/Principal Findings Ninety seven milk samples from cows with clinical mastitis and 31 nasal swabs from milkmen were collected (one sample per cow/human). Fifty eight (60%) Gram-positive isolates namely Staphylococci (21), Enterococci (16), Streptococci (13), Lactococci (5), Micrococci (2) and Arcanobacteria (1) were detected in cows; only one grew Staphylococcus aureus. Furthermore, 24 (25%) coliforms namely Escherichia coli (12), Klebsiella oxytoca (5), Proteus vulgaris (2), Serratia (2), Citrobacter (1), Cedecea (1) and Leclercia (1) were identified. From humans, 24 Gram-positive bacteria grew, of which 11 were Staphylococci (35%) including four Staphylococcus aureus. Upon susceptibility testing, methicillin-resistant coagulase-negative staphylococci (CoNS) were prevalent; 57%, 12/21 in cows and 64%, 7/11 in humans. However, methicillin-resistant Staphylococcus aureus was not detected. Furthermore, methicillin and vancomycin resistant CoNS were detected in cows (Staphylococcus hominis, Staphylococcus lugdunensis) and humans (Staphylococcus scuiri). Also, vancomycin and daptomycin resistant Enterococci (Enterococcus faecalis and Enterococcus faecium, respectively) were detected in cows. Coliforms were less resistant with three pan-susceptible isolates. However, multidrug resistant Klebsiella, Proteus, Serratia, Cedecea, and Citrobacter were detected. Lastly, similar species grew from human and bovine samples but on genotyping, the isolates were found to be different. Interestingly, human and bovine Staphylococcus aureus were genetically similar (spa-CC435

  7. Antimicrobial Susceptibility and Resistance Patterns among Helicobacter pylori Strains from The Gambia, West Africa

    PubMed Central

    Berg, Douglas E.; Antonio, Martin; Corrah, Tumani; Tapgun, Mary; Walton, Robert; Thomas, Vivat; Galano, Juan J.; Sancho, Javier; Adegbola, Richard A.; Thomas, Julian E.

    2013-01-01

    Helicobacter pylori is a globally important and genetically diverse gastric pathogen that infects most people in developing countries. Eradication efforts are complicated by antibiotic resistance, which varies in frequency geographically. There are very few data on resistance in African strains. Sixty-four Gambian H. pylori strains were tested for antibiotic susceptibility. The role of rdxA in metronidazole (Mtz) susceptibility was tested by DNA transformation and sequencing; RdxA protein variants were interpreted in terms of RdxA structure. Forty-four strains (69%) were resistant to at least 8 μg of Mtz/ml. All six strains from infants, but only 24% of strains from adults, were sensitive (P = 0.0031). Representative Mtz-resistant (Mtzr) strains were rendered Mtz susceptible (Mtzs) by transformation with a functional rdxA gene; conversely, Mtzs strains were rendered Mtzr by rdxA inactivation. Many mutations were found by Gambian H. pylori rdxA sequencing; mutations that probably inactivated rdxA in Mtzr strains were identified and explained using RdxA protein's structure. All of the strains were sensitive to clarithromycin and erythromycin. Amoxicillin and tetracycline resistance was rare. Sequence analysis indicated that most tetracycline resistance, when found, was not due to 16S rRNA gene mutations. These data suggest caution in the use of Mtz-based therapies in The Gambia. The increasing use of macrolides against respiratory infections in The Gambia calls for continued antibiotic susceptibility monitoring. The rich variety of rdxA mutations that we found will be useful in further structure-function studies of RdxA, the enzyme responsible for Mtz susceptibility in this important pathogen. PMID:23263004

  8. Evaluation of the pathogenic potential, antimicrobial susceptibility, and genomic relations of Yersinia enterocolitica strains from food and human origin.

    PubMed

    Lucero-Estrada, Cecilia S M; Soria, José Miguel; Favier, Gabriela Isabel; Escudero, María Esther

    2015-11-01

    Yersinia enterocolitica is a food-borne pathogen that causes gastroenteritis with occasional postinfection sequels. This study was aimed to determinate the pathogenic potential, antimicrobial susceptibility, and genomic relationships of Y. enterocolitica strains of different bioserotypes (B/O) isolated from foods and human samples in San Luis, Argentina. Strains obtained by culture were bioserotyped and characterized by phenotypic and genotypic virulence markers, antimicrobial susceptibility, and pulsed-field gel electrophoresis (PFGE). Yersinia enterocolitica was detected in 9.2% of 380 samples, with a distribution of 10.6% (30/284) for food products and 5.2% (5/96) for human samples. Regarding the pathogenic potential, B1A strains of different serotypes were virF(-) ail(-), of which 72.0% (13/18) were ystB(+) with virulence-related phenotypic characteristics. Among B2/O:9 isolates, 75.0% (9/12) exhibited the genotype virF(+) ail(+) ystB(-) along with phenotypic traits associated with virulence; the same genotype was observed in 80.0% (4/5) of B3/O:3 and B3/O:5 strains. By PFGE, it was possible to separate Y. enterocolitica biotypes into 4 clonal groups (A to D) with 23 genomic types, generating a discriminatory index of 0.96. All isolates were susceptible to antimicrobials used for clinical treatment. This study highlights the presence of pathogenic bioserotypes and the high genomic diversity of the Y. enterocolitica strains isolated in our region. PMID:26370735

  9. Extended-spectrum β-lactamases producing Klebsiella pneumoniae isolated in two hospitals in Goiânia/Brazil: detection, prevalence, antimicrobial susceptibility and molecular typing

    PubMed Central

    dos Santos, Daniella Fabíola; Pimenta, Fabiana Cristina; Alves, Rodrigo; Montalvão, Edlaine Rodrigues; dos Santos, Daniela Braz; do Carmo Filho, José Rodrigues

    2008-01-01

    This study was developed to evaluate the prevalence of extended-spectrum β-lactamases (ESBL) producing Klebsiella pneumoniae in two hospitals (A and B) in Goiânia, GO, Brazil. The antimicrobial susceptibility of the isolates was determined using the MicroScan WalkAway (Dade Behring, USA). Tests to evaluate the genetic correlation between the isolates were also performed. For the ESBL phenotypic test, the Double-disk diffusion (DD) method was used. The strains isolated in Hospital B were submitted to DNA analysis by pulsed-field gel electrophoresis (PFGE). The study showed high prevalence of ESBL-producing K. pneumoniae (25% in hospital A and 66.7% in hospital B), with high rates of antimicrobial resistance. The most active compound was imipenem (100% susceptibility in vitro). The PFGE test showed similiarity in five strains and variability in six strains.The high prevalence of ESBL-producing Klebsiella may be due to individual selection and to dissemination of a common strain. PMID:24031275

  10. Antimicrobial susceptibility monitoring of bacterial pathogens isolated from respiratory tract infections in dogs and cats across Europe: ComPath results.

    PubMed

    Morrissey, Ian; Moyaert, Hilde; de Jong, Anno; El Garch, Farid; Klein, Ulrich; Ludwig, Carolin; Thiry, Julien; Youala, Myriam

    2016-08-15

    ComPath is a pan-European resistance monitoring programme collecting bacterial pathogens from dogs and cats. We present data for respiratory tract infection (RTI) isolates collected between 2008 and 2010. Antimicrobial minimal inhibitory concentrations (MICs) were determined and susceptibility calculated following Clinical Laboratory Standards Institute (CLSI) standards for veterinary medicine. The main pathogen from dogs was Staphylococcus intermedius Group (49/215, 22.8%) which was >90% susceptible to most antimicrobials (including oxacillin - 93.9%; 3 isolates confirmed mecA-positive) but only 59.2%, 73.5% and 87.8% susceptible to tetracycline, chloramphenicol and penicillin. Bordetella bronchiseptica (48/215, 22.3%), streptococci (36/215, 16.7%), Escherichia coli (24/215, 11.2%) and Pasteurella multocida (23/215, 10.7%) were also found in dog RTI. There are no breakpoints for Bordetella bronchiseptica. Most streptococci were penicillin- chloramphenicol-, ampicillin- and pradofloxacin-susceptible. None were enrofloxacin-resistant but 6 isolates (16.7%) were of intermediate susceptibility. The least active agent against streptococci was tetracycline (47.2% susceptible). For E. coli, 37.5% were ampicillin-susceptible but 83.3% were amoxicillin/clavulanic acid-susceptible. Only chloramphenicol showed susceptibility>90% against E. coli, with 66.7% tetracycline-susceptible and 79.2% to 87.5% susceptibility to enrofloxacin, trimethoprim-sulfamethoxazole or pradofloxacin. P. multocida were susceptible to pradofloxacin (no other breakpoints are available). The main pathogen from cats was P. multocida (82/186, 44.1%), where only pradofloxacin has breakpoints (100% susceptible). Streptococci were also collected from cats (25/186, 13.4%) and were >90% susceptible to all antimicrobials except tetracycline (36% susceptible). Most susceptibility was calculated with human-derived breakpoints and some antimicrobials had no breakpoints. Therefore predictions of clinical utility

  11. Meningococcal disease: history, epidemiology, pathogenesis, clinical manifestations, diagnosis, antimicrobial susceptibility and prevention.

    PubMed

    Manchanda, V; Gupta, S; Bhalla, P

    2006-01-01

    Meningoccocal disease has repeatedly caused outbreaks worldwide. There has been sudden surge of cases of meningococcemia and meningococcal meningitis in early 2005 in Delhi, India and neighboring states of Uttar Pradesh and Haryana. As of June 17, 2005, 429 probable cases of meningococcal disease have been reported in Delhi out of which 128 cases have revealed microbiological evidence of Neisseria meningitidis. It is possible that the number of cases was in excess of the numbers notified. During this episode drug susceptibility testing by MIC method (E-test) using break points recently recommended by NCCLS/CLSI, revealed that all isolates were sensitive to penicillin, ampicillin, rifampicin and ceftriaxone. As regards to ciprofloxacin, about two third of the isolates tested were found to be 'non-susceptible' (MIC =0.03microg/mL- 0.190microg/mL). All the isolates were found resistant to cotrimoxazole (MIC> 16microg/mL). Repeated outbreaks, decreased susceptibility to ciprofloxacin, which is commonly used for chemoprophylaxis of meningococcal disease, highlights the need for a constant surveillance system. Present review deals with various aspects of Neisseria meningitidis and meningococcal disease in view of recent episode. PMID:16505549

  12. COMPARISON BETWEEN AUTOMATED SYSTEM AND PCR-BASED METHOD FOR IDENTIFICATION AND ANTIMICROBIAL SUSCEPTIBILITY PROFILE OF CLINICAL Enterococcus spp

    PubMed Central

    Furlaneto-Maia, Luciana; Rocha, Kátia Real; Siqueira, Vera Lúcia Dias; Furlaneto, Márcia Cristina

    2014-01-01

    Enterococci are increasingly responsible for nosocomial infections worldwide. This study was undertaken to compare the identification and susceptibility profile using an automated MicrosScan system, PCR-based assay and disk diffusion assay of Enterococcus spp. We evaluated 30 clinical isolates of Enterococcus spp. Isolates were identified by MicrosScan system and PCR-based assay. The detection of antibiotic resistance genes (vancomycin, gentamicin, tetracycline and erythromycin) was also determined by PCR. Antimicrobial susceptibilities to vancomycin (30 µg), gentamicin (120 µg), tetracycline (30 µg) and erythromycin (15 µg) were tested by the automated system and disk diffusion method, and were interpreted according to the criteria recommended in CLSI guidelines. Concerning Enterococcus identification the general agreement between data obtained by the PCR method and by the automatic system was 90.0% (27/30). For all isolates of E. faecium and E. faecalis we observed 100% agreement. Resistance frequencies were higher in E. faecium than E. faecalis. The resistance rates obtained were higher for erythromycin (86.7%), vancomycin (80.0%), tetracycline (43.35) and gentamicin (33.3%). The correlation between disk diffusion and automation revealed an agreement for the majority of the antibiotics with category agreement rates of > 80%. The PCR-based assay, the van(A) gene was detected in 100% of vancomycin resistant enterococci. This assay is simple to conduct and reliable in the identification of clinically relevant enterococci. The data obtained reinforced the need for an improvement of the automated system to identify some enterococci. PMID:24626409

  13. Prevalence and antimicrobial susceptibility of Listeria monocytogenes on chicken carcasses in Bandung, Indonesia.

    PubMed

    Sugiri, Yoni Darmawan; Gölz, Greta; Meeyam, Tongkorn; Baumann, Maximilian P O; Kleer, Josef; Chaisowwong, Warangkhana; Alter, Thomas

    2014-08-01

    This study was conducted to determine the prevalence and quantify the number of Listeria monocytogenes in fresh chicken carcasses sold in traditional markets and supermarkets in Bandung, West Java, Indonesia, and to determine the antimicrobial resistance patterns of the isolated L. monocytogenes strains. The overall prevalence of L. monocytogenes in chicken carcasses was 15.8% (29/184). When comparing samples from traditional markets and supermarkets, no significant difference in the L. monocytogenes prevalence was detectable (15.2 versus 16.3%). Of the samples, 97.3% had L. monocytogenes counts <100 CFU/g, 2.2% had L. monocytogenes counts between 101 and 1,000 CFU/g, and 0.5% had L. monocytogenes counts of 1,001 to 10,000 CFU/g. Of the isolates, 27.6% were resistant to at least one of the 10 antimicrobials tested, with the major resistant phenotypes to penicillin (17.2%), ampicillin (6.9%), and erythromycin (6.9%). All 29 isolates recovered in this study were grouped into the molecular serogroup IIb, comprising the serovars 1/2b, 3b, and 7. PMID:25198605

  14. Identification of penicillinase producing Neisseria gonorrhoeae in Chile during clinical and microbiological study of gonococcal susceptibility to antimicrobial agents.

    PubMed Central

    Garcia Moreno, J; Dillon, J R; Arroyave, R; Maldonado, A; Fich, F; Salvo, A; Villalobos, D; Vincent, P; Pauze, M

    1987-01-01

    The first penicillinase producing isolates of Neisseria gonorrhoeae (PPNG) identified in Chile were discovered during a clinical and microbiological study to compare the efficacy of penicillin (4.8 MIU aqueous procaine penicillin G plus 1 g oral probenecid) and tetracycline (1.5 g followed by 500 mg four times daily for four days) treatment regimens for acute uncomplicated gonorrhoea. Penicillin treatment was effective in 93.1% (282) of 303 patients, whereas tetracycline was effective in 98.3% (233) of 237 patients. Six of the penicillin treatment failures were attributable to PPNG strains. In all, 21 PPNG strains were identified during the study. They were genetically identical, having a wild type auxotype, a WII/III serotype (serovar Bajk), and carrying cryptic and transfer plasmids and an Asian type penicillinase producing plasmid. In addition, 674 non-PPNG isolates were tested for their susceptibility to eight antimicrobials. Over 95% were sensitivie to 1 mg/l of penicillin, ampicillin, cefotaxime, cefuroxime, and erythromycin, over 90% were sensitive to 1 mg/l of tetracycline and 2 mg/l of thiamphenicol, and all were sensitive to spectinomycin. Of 226 non-PPNG isolates characterised for plasmid content and auxotype, 90% (205) were either wild type or proline requiring, 67% (153) carried only the cryptic plasmid, and a further 31% (71) carried both cryptic and transfer plasmids. Unusually, three of four isolates lacking the cryptic plasmid carried only the transfer plasmid. Images PMID:3102348

  15. In Vitro Antimicrobial Susceptibility to Isepamicin of 6,296 Enterobacteriaceae Clinical Isolates Collected at a Tertiary Care University Hospital in Greece

    PubMed Central

    Maraki, Sofia; Samonis, George; Karageorgopoulos, Drosos E.; Mavros, Michael N.; Kofteridis, Diamantis

    2012-01-01

    The reevaluation of “forgotten” antibiotics can identify new therapeutic options against extensively drug-resistant Gram-negative pathogens. We sought to investigate isepamicin in this regard. We retrospectively evaluated the antimicrobial susceptibility to isepamicin of Enterobacteriaceae sp. isolates from unique patients, collected at the microbiological laboratory of the University Hospital of Heraklion, Crete, Greece, from 2004 to 2009. Susceptibility testing was done with the automated Vitek 2 system. The breakpoints for susceptibility to isepamicin, tigecycline, and other antibiotics were those proposed by the Comité de l'Antibiogramme de la Société Française de Microbiologie (CA-SFM), the FDA, and the CLSI, respectively. A total of 6,296 isolates were studied, including primarily 3,401 (54.0%) Escherichia coli, 1,040 (16.5%) Klebsiella pneumoniae, 590 (9.4%) Proteus mirabilis, and 460 (7.3%) Enterobacter sp. isolates. Excluding the species with intrinsic resistance to each antibiotic, antimicrobial susceptibility was highest for colistin (5,275/5,441 isolates [96.9%]) and isepamicin (6,103/6,296 [96.9%]), followed by meropenem (5,890/6,296 [93.6%]), imipenem (5,874/6,296 [93.3%]), and amikacin (5,492/6,296 [87.2%]). The antimicrobial susceptibility of the 1,040 K. pneumoniae isolates was highest for isepamicin (95.3%), followed by colistin (89.3%) and meropenem (63.0%). Regarding resistant K. pneumoniae isolates, susceptibility to isepamicin was observed for 91.1% of the 392, 87.7% of the 375, and 85.6% of the 111 isolates that were nonsusceptible to the carbapenems, all other aminoglycosides, and colistin, respectively. Isepamicin exhibited high in vitro activity against almost all of the Enterobacteriaceae species. It could particularly serve as a last-resort therapeutic option for carbapenem-resistant K. pneumoniae in our region, where it is endemic, as it does not show considerable cross-resistance with other aminoglycosides. PMID:22391548

  16. Are Creativity Tests Susceptible to Coaching?

    ERIC Educational Resources Information Center

    Fairweather, Elizabeth C.; Cramond, Bonnie; Landis, Rebecca Nordin

    2015-01-01

    Critics of creativity tests, some of which are used widely in determining student eligibility for special educational opportunities such as gifted programs, claim that scores on these tests can be improved with specific training on the scoring components of the tests. However, we could find no empirical evidence supporting this claim. So, we…

  17. Antimicrobial activities of natural antimicrobial compounds against susceptible and antibiotic-resistant pathogens in the absence and presence of food

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In an effort to improve microbial food safety, we are studying the antimicrobial activities of different classes of natural compounds including plant essential oils, apple, grape, olive, and tea extracts, bioactive components, and seashell-derived chitosans against multiple foodborne pathogens in cu...

  18. Effect of androgens and glucocorticoids on microbial growth and antimicrobial susceptibility.

    PubMed

    Plotkin, Balbina J; Roose, Robert J; Erikson, Quenby; Viselli, Susan M

    2003-12-01

    The effects of androgens, testosterone and dihydrotestosterone (DHT), of an environmental anti-androgen, 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (DDE), and of glucocorticoids, hydrocortisone and dexamethasone, on growth kinetics and antibiotic susceptibility of E. faecalis, E. coli, P. aeurginosa, and S. aureus were measured. For P. aeurginosa, the presence of either DHT or DDE caused at least a fourfold shift in the minimum inhibitory concentration (MIC) of cefepime and tobramycin. DHT and DDE also affected the response of E. faecalis to meropenem and norfloxacin, resulting in a shift from sensitive to intermediate resistance (four-fold increase in MIC). Hydrocortisone (2 microM) induced an increase in the sensitivity of S. aureus to erythromycin, as compared to hormone-free control (from 0.5 to 0.06 microg/mL). The susceptibility pattern of E. coli was unaffected by the hormones tested. These changes in susceptibility to antibiotics were unrelated to alterations in growth kinetics. For all organisms tested, the alterations in MICs occurred only in the presence of hormone, indicative of changes in the phenotype of these stable quality control strains. PMID:14756537

  19. Efflux pump activity in fluoroquinolone and tetracycline resistant Salmonella and E. coli implicated in reduced susceptibility to household antimicrobial cleaning agents.

    PubMed

    Thorrold, C A; Letsoalo, M E; Dusé, A G; Marais, E

    2007-02-15

    It has been shown that the inappropriate use of antimicrobial household agents selects for organisms with resistance mechanisms (e.g. efflux pumps), which could lead to the development of antibiotic resistance. The reverse hypothesis, that antibiotic-resistant organisms become tolerant to other antibacterial agents (e.g. disinfectants) due to the action of efflux pumps, has however not been extensively examined. The objective of this study was to establish whether there is a link between antibiotic resistance in potential gastrointestinal pathogens and reduced sensitivity of these organisms to commonly used household antimicrobial agents. In this study, tetracycline and ofloxacin sensitive and resistant Escherichia coli (9 strains) and Salmonella spp. (8 strains) were isolated from poultry and clinical samples. In order to assess whether these bacteria had active efflux pumps, ethidium bromide accumulation assays were performed. Extrusion of the active components of three commercial household agents (triclosan, sodium salicylate, and ortho-phenylphenol) by efflux pumps was tested using spectrophotometric accumulation assays. In order to simulate the kitchen environment, in-use disinfectant testing using the commercial household agents was performed to determine changes in their efficacy due to antibiotic resistance. Active efflux pump activity and extrusion of all three active ingredients was observed only in the antibiotic resistant organisms. The antibiotic sensitive bacteria were also more susceptible than the resistant isolates to the household antimicrobial agents at concentrations below that recommended by the manufacturer. These resistant bacteria could potentially be selected for and result in hard to treat infections. PMID:17126442

  20. Comparison of E-test with agar dilution methods in testing susceptibility of N. gonorrhoeae to azithromycin.

    PubMed

    Yasin, R M; Suan, K A; Meng, C Y

    1997-05-01

    A single dose of a new antibiotic, azithromycin, has been shown to be effective in the treatment of uncomplicated Neisseria gonorrhoeae. A clinical study was conducted to assess the in vitro susceptibility of N gonorrhoeae to azithromycin and compare the reliability of results obtained using the new E-test methodology for determination of the minimum inhibitory concentration (MIC) of antibiotic with those obtained through the standard agar dilution method. 135 clinical isolates of N gonorrhoeae were obtained from patients attending hospital-based sexually transmitted disease clinics in five geographic locations in Malaysia. 76 of the isolates were penicillinase-producing N gonorrhoeae and 69 were high-level tetracycline-resistant N gonorrhoeae. All isolates were susceptible to azithromycin based on the susceptible MIC breakpoint of 2.0 mcg/ml. The MICs ranged from 0.0078-0.25 mcg/ml by agar dilution method and from 0.016-0.50 mcg/ml by E-test. Agreement between these two methods was 97.8%. The single-dose regime and good antigonococcal and antichlamydial activity of azithromycin make this antibiotic a suitable treatment choice. Moreover, the findings of this study suggest that the simpler, faster E-test is as reliable as the agar dilution method. Given the tendency of the antimicrobial susceptibility pattern of N gonorrhoeae to change rapidly, it is important to monitor MICs to detect the emergence of resistance. PMID:9153733

  1. Antimicrobial susceptibility and beta-lactamase production of selected gram-negative bacilli from two Croatian hospitals: MYSTIC study results.

    PubMed

    Bedenic, B; Goic-Barisic, I; Budimir, A; Tonkic, M; Mihajkevic, L J; Novak, A; Sviben, M; Plecko, V; Punda-Polic, V; Kalenic, S

    2010-06-01

    The meropenem yearly Susceptibility Test Information Collection (MYSTIC) programme is a global, longitudinal resistance surveillance network that monitors the activity of meropenem and compares its activity with other broadspectrum antimicrobial agents. We now report the antimicrobial efficacy of meropenem compared to other broad-spectrum agents within the selective Gram-negative pathogen groups from two Croatian Hospitals investigated between 2002-2007. A total of 1510 Gram-negative pathogens were tested and the minimum-inhibitory concentrations (MICs) were determined by broth microdilution method according to CLSI.There was no resistance to either imipenem or meropenem observed for Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis in both medical centers. High resistance rates of K. pneumoniae to ceftazidime (18%), cefepime (17%) and gentamicin (39%) are raising concern. Acinetobacter baumannii turned out to be the most resistant Gram-negative bacteria with 81% resistant to ceftazidime, 73% to cefepime, 69% to gentamicin and 71% to ciprofloxacin. Almost 20% of Pseudomonas aeruginosa strains were resistant to imipenem, 13% to meropenem, 69% to gentamicin and 38% to ciprofloxacin.The prevalence of extended-spectrum beta-lactamases (ESBLs) in E. coli was 10% and in K. pneumoniae 49%. PCR and sequencing of the amplicons revealed the presence of SHV-5 in nine E. coli strains and additional tem-1 beta-lactamase five strains. Five K. pneumoniae strains were positive for bla(SHV-5 )gene. Eight ESBL positive Enterobacter spp. strains were found to produce tem and CtX-m beta-lactamases. Plasmid-mediated AmpC beta-lactamases were not found among K. pneumoniae, E. coli and Enterobacter spp. Three A. baumannii strains from Zagreb University Center were identified by multiplex PCR as OXA-58 like producers. Six A. baumannii strains from Split University Center were found to possess an ISAba1 insertion sequence upstream of bla(OXA-51 )gene. According to our results

  2. Trends in the susceptibility of commonly encountered clinically significant anaerobes and susceptibilities of blood isolates of anaerobes to 16 antimicrobial agents, including fidaxomicin and rifaximin, 2008-2012, northern Taiwan.

    PubMed

    Wang, F D; Liao, C H; Lin, Y T; Sheng, W H; Hsueh, P R

    2014-11-01

    We investigated the antimicrobial resistance trends and profiles of clinical anaerobic isolates in northern Taiwan. Trends in the susceptibility of five commonly encountered clinical anaerobic isolates to seven agents from 2008 to 2012 were measured using the Cochran-Armitage trend test. The minimum inhibitory concentrations (MICs) of 16 antimicrobial agents, including fidaxomicin and rifaximin, against anaerobic blood isolates from two medical centers were determined using the agar dilution method. During the study period, susceptibility data on 11,105 isolates were evaluated. Metronidazole and chloramphenicol retained excellent activities. Around 20-30 % of isolates of Bacteroides and Prevotella species were resistant to ampicillin-sulbactam, cefmetazole, flomoxef, and clindamycin. Of the 507 tested blood isolates, the rates of resistance to commonly used agents were much higher, namely, 16.2 % for amoxicillin-clavulanate, 15.6 % for ampicillin-sulbactam, 24.7 % for cefmetazole, and 36.1 % for clindamycin. Notably, 13.5 % of B. fragilis isolates were resistant to ertapenem. Also, 15.2 % of B. uniformis, 17.2 % of other Bacteroides species, 14.3 % of Prevotella species, and 14 % of Clostridium other than C. perfringens isolates were resistant to moxifloxacin. Cefoperazone-sulbactam was active against most isolates, except for Clostridium species other than perfringens (resistance rate, 18.6 %). Fidaxomicin exerted poor activities against most anaerobes tested (MIC90 of >128 μg/ml for B. fragilis and all isolates), except for C. perfringens (MIC90 of 0.03 μg/ml) and Peptostreptococcus micros (MIC90 of 2 μg/ml). However, rifaximin showed a wide range of susceptibilities against the tested anaerobes (MIC90 of 0.5 μg/ml for B. fragilis). The emergence of resistance to ertapenem and moxifloxacin among bacteremic anaerobes highlights the need for continuous monitoring. PMID:24930042

  3. Reduced Susceptibility to Rifampicin and Resistance to Multiple Antimicrobial Agents among Brucella abortus Isolates from Cattle in Brazil

    PubMed Central

    Barbosa Pauletti, Rebeca; Reinato Stynen, Ana Paula; Pinto da Silva Mol, Juliana; Seles Dorneles, Elaine Maria; Alves, Telma Maria; de Sousa Moura Souto, Monalisa; Minharro, Silvia; Heinemann, Marcos Bryan; Lage, Andrey Pereira

    2015-01-01

    This study aimed to determine the susceptibility profile of Brazilian Brucella abortus isolates from cattle to eight antimicrobial agents that are recommended for the treatment of human brucellosis and to correlate the susceptibility patterns with origin, biotype and MLVA16-genotype of the strains. Screening of 147 B. abortus strains showed 100% sensitivity to doxycycline and ofloxacin, one (0.68%) strain resistant to ciprofloxacin, two strains (1.36%) resistant to streptomycin, two strains (1.36%) resistant to trimethoprim-sulfamethoxazole and five strains (3.40%) resistant to gentamicin. For rifampicin, three strains (2.04%) were resistant and 54 strains (36.73%) showed reduced sensitivity. Two strains were considered multidrug resistant. In conclusion, the majority of B. abortus strains isolated from cattle in Brazil were sensitive to the antimicrobials commonly used for the treatment of human brucellosis; however, a considerable proportion of strains showed reduced susceptibility to rifampicin and two strains were considered multidrug resistant. Moreover, there was no correlation among the drug susceptibility pattern, origin, biotype and MLVA16-genotypes of these strains. PMID:26181775

  4. Sporulation properties and antimicrobial susceptibility in endemic and rare Clostridium difficile PCR ribotypes.

    PubMed

    Zidaric, Valerija; Rupnik, Maja

    2016-06-01

    Increased sporulation and antibiotic resistance have been proposed to be associated with certain Clostridium difficile epidemic strains such as PCR ribotype 027. In this study we examined these properties in another widespread PCR ribotype, 014/020, in comparison to prevalent PCR ribotype 002 and a group of rarely represented PCR ribotypes. Highest sporulation was observed in 014/020 strains at 24 h, while after 72 h PCR ribotype 002 and rare PCR ribotypes formed higher total number of spores. PCR ribotype 014/020 strains exhibited slightly higher resistance to tested antimicrobials, followed by group of rare PCR ribotypes and less common PCR ribotype 002. Neither sporulation properties nor antibiotic resistance clearly differed in endemic and rare strains. PMID:27095618

  5. Surveillance of antimicrobial susceptibility of aerobic and facultative Gram-negative bacilli isolated from patients with intra-abdominal infections in China: the 2002-2009 Study for Monitoring Antimicrobial Resistance Trends (SMART).

    PubMed

    Yang, Qiwen; Wang, Hui; Chen, Minjun; Ni, Yuxing; Yu, Yunsong; Hu, Bijie; Sun, Ziyong; Huang, Wenxiang; Hu, Yunjian; Ye, Huifen; Badal, Robert E; Xu, Yingchun

    2010-12-01

    The objective of this study was to investigate the distribution and susceptibility of aerobic and facultative Gram-negative bacilli (GNB) isolated from patients with intra-abdominal infections (IAIs) in China. From 2002 to 2009, minimum inhibitory concentrations of 14 antibiotics for 3420 aerobic and facultative GNB from up to eight hospitals in six cities were determined by the broth microdilution method. Enterobacteriaceae comprised 82.9% (2834/3420) of the total isolates, with Escherichia coli (49.2%) being the most commonly isolated species followed by Klebsiella pneumoniae (17.0%), Enterobacter cloacae (5.8%) and Citrobacter freundii (2.3%). Amongst the antimicrobial agents tested, the three carbapenems (ertapenem, imipenem and meropenem) were the most active agents against Enterobacteriaceae, with susceptibility rates of 96.1-99.6% (2002-2009), 98.2-100% (2002-2009) and 99.6-100% (2002-2004), respectively, followed by amikacin (86.8-95.1%) and piperacillin/tazobactam (84.5-94.3%). Susceptibility rates of all tested third- and fourth-generation cephalosporins against Enterobacteriaceae declined by nearly 30%, with susceptibility rates of 40.2%, 39.1%, 56.3% and 51.8% in 2009 for ceftriaxone, cefotaxime, ceftazidime and cefepime, respectively. The occurrence of extended-spectrum β-lactamases increased rapidly, especially for E. coli (from 20.8% in 2002 to 64.9% in 2009). Susceptibility of E. coli to ciprofloxacin decreased from 57.6% in 2002 to 24.2% in 2009. The least active agent against Enterobacteriaceae was ampicillin/sulbactam (SAM) (25.3-44.3%). In conclusion, Enterobacteriaceae were the major pathogens causing IAIs, and carbapenems retained the highest susceptibility rates over the 8-year study period. Third- and fourth-generation cephalosporins, fluoroquinolones and SAM may not be ideal choices for empirical therapy of IAIs in China. PMID:21036547

  6. Antimicrobial susceptibility assays based on the quantification of bacterial lipopolysaccharides via a label free lectin biosensor.

    PubMed

    Ma, Fen; Rehman, Abdul; Sims, Matthew; Zeng, Xiangqun

    2015-04-21

    A label free lectin biosensor developed in our laboratory that can quantitatively measure the binding between the lectin immobilized at the carbohydrate sensor surface and the lipopolysaccharide (LPS) on Gram-negative bacteria was demonstrated for an antibiotic susceptibility assay. The biosensor utilizes a polythiophene interface containing fused quinone moieties glycosylated to form a carbohydrate platform for the immobilization of Concanavalin A (Con A) and is capable of LPS binding measurements via orthogonal quartz crystal microbalance and electrochemical readouts (EQCM). Such orthogonal transduction provides cross-validation, better sensor sensitivity, and a large dynamic range of the measurements. We have applied this label free lectin biosensor for a new antibiotic susceptibility assay by characterizing the antimicrobial activities of various antibiotics (i.e., ciprofloxacin, ceftriaxone, and tetracycline) against Escherichia coli W1485 as a model system. The label free biosensor allows both end point and real time measurements of antibiotic effects on the bacterial cell surface LPS, which is shown to correlate to their antibiotic effects. At the end point, after 18 h incubation of bacterial cells with these three antibiotics respectively, the bacterial LPS binding signal was reduced to 23%, 27%, and 38%, respectively, for the three antibiotics, indicating that ciprofloxacin is the most effective against this E. coli strain. Real time measurements at the 1 h time point showed a similar trend with a reduction of binding to 91%, 93%, and 95%, respectively. From the binding kinetics of these measurements, the relaxation time (τ) was obtained, where higher τ value means slow binding interactions between the lectin and the bacterial LPS. The obtained order of τ, (i.e., τciprofloxacin > τceftriaxone > τtetracycline) again indicated that ciprofloxacin has more bactericidal activity than the other two antibiotics with the same concentrations. Thus, we are

  7. Digital Quantification of DNA Replication and Chromosome Segregation Enables Determination of Antimicrobial Susceptibility after only 15 Minutes of Antibiotic Exposure.

    PubMed

    Schoepp, Nathan G; Khorosheva, Eugenia M; Schlappi, Travis S; Curtis, Matthew S; Humphries, Romney M; Hindler, Janet A; Ismagilov, Rustem F

    2016-08-01

    Rapid antimicrobial susceptibility testing (AST) would decrease misuse and overuse of antibiotics. The "holy grail" of AST is a phenotype-based test that can be performed within a doctor visit. Such a test requires the ability to determine a pathogen's susceptibility after only a short antibiotic exposure. Herein, digital PCR (dPCR) was employed to test whether measuring DNA replication of the target pathogen through digital single-molecule counting would shorten the required time of antibiotic exposure. Partitioning bacterial chromosomal DNA into many small volumes during dPCR enabled AST results after short exposure times by 1) precise quantification and 2) a measurement of how antibiotics affect the states of macromolecular assembly of bacterial chromosomes. This digital AST (dAST) determined susceptibility of clinical isolates from urinary tract infections (UTIs) after 15 min of exposure for all four antibiotic classes relevant to UTIs. This work lays the foundation to develop a rapid, point-of-care AST and strengthen global antibiotic stewardship. PMID:27357747

  8. Rapid purity check method for susceptibility testing of M. tuberculosis complex with the MGIT 960 system.

    PubMed

    Huang, Tsi-Shu; Liu, Yung-Ching; Tu, Hui-Zin; Sy, Cheng-Len; Chen, Yao-Shen; Chen, Bao-Chen

    2007-01-01

    The Bactec MGIT 960 system is a rapid and reliable automated method for drug susceptibility testing of Mycobacterium tuberculosis complex (MTBC) that yields a high percentage of agreement with the standard method. The microscopic cord morphology of M. tuberculosis in liquid medium is characteristic, and readily differentiates MTBC from nontuberculous mycobacteria (NTM). The goals of this study were to describe the microscopic and macroscopic growth morphology of MTBC in antimicrobial-containing MGIT tubes and to evaluate the usefulness of the growth appearance during purity checking. The macroscopic cotton wool-like appearance of MTBC isolates in isoniazid (INH), streptomycin (SM), rifampin (RMP), and ethambutol (EMB)-containing tubes was observed in 97, 90, 93, and 71% of the isolates, respectively. The percentage of typical cord, loose, or frayed rope microscopic features in smears prepared from MTBC-positive cultures of INH, SM, RMP, and EMB-containing tubes was 96, 86, 97, and 71%, respectively. The sensitivity of the macroscopic morphology for predicting the purity of drug-containing MGIT tubes was 93%, while the microscopic morphology predicted the purity with a sensitivity rate of 92%. We found that simply examining the macroscopic morphology of the antimicrobial-containing MGIT tubes of drug-resistant MTBC isolates is useful in preventing false resistant results of susceptibility testing by the MGIT 960 system. PMID:18000288

  9. Antifungal Susceptibility Testing of Ascomycetous Yeasts Isolated from Animals.

    PubMed

    Álvarez-Pérez, Sergio; García, Marta E; Peláez, Teresa; Martínez-Nevado, Eva; Blanco, José L

    2016-08-01

    Recent studies suggest that antifungal resistance in yeast isolates of veterinary origin may be an underdiagnosed threat. We tested a collection of 92 ascomycetous yeast isolates that were obtained in Spain from birds, mammals and insects for antifungal susceptibility. MICs to amphotericin B and azoles were low, and no resistant isolates were detected. Despite these results, and given the potential role of animals as reservoirs of resistant strains, continuous monitoring of antifungal susceptibility in the veterinary setting is recommended. PMID:27216048

  10. Microbiological quality of water from the rivers of Curitiba, Paraná State, Brazil, and the susceptibility to antimicrobial drugs and pathogenicity of Escherichia coli.

    PubMed

    Giowanella, Melissa; Bozza, Angela; do Rocio Dalzoto, Patricia; Dionísio, Jair Alves; Andraus, Sumaia; Guimarães, Edson Luiz Gomes; Pimentel, Ida Chapaval

    2015-11-01

    Water safety is determined by several markers, and Escherichia coli is one of the most important indicators of water quality. The objective of this study was to evaluate the microbiological parameters in environmental samples of fresh water from rivers of Curitiba and its metropolitan area in Paraná State, Brazil. In addition, we evaluated the pathogenicity and susceptibility to antimicrobial drugs in E. coli. These evaluations were performed by quantitative and qualitative methods employing selective media for isolating thermotolerant coliforms and biochemical tests for identifying E. coli. Pathogenic strains of E. coli were detected by PCR multiplex using specific primers. From the water samples, 494 thermotolerant coliforms were obtained, of which 96 (19.43%) isolates were characterized as E. coli. Three isolates were identified as enteroaggregative E. coli, one as enterotoxigenic E. coli, one as enteropathogenic E. coli, and two carried the Eae virulence gene. E. coli susceptibility to commonly employed antimicrobial drugs was analyzed by the disc diffusion method. The results showed 49 (51.04%) isolates resistant to all the drugs assayed, 16 (16.67%) with an intermediate resistance to all drugs, and 31 (32.29%) intermediately or fully resistant to one or more drugs tested. The highest rate of resistance was observed for tetracycline 30 μg, streptomycin 10 μg, and ceftazidime 30 μg. Detection of E. coli is associated with water contamination by fecal material from humans and warm-blooded animals. The occurrence of resistant strains can be the result of the indiscriminate use of antimicrobial drugs and poor sanitation in the areas assayed. PMID:26439126

  11. Polyclonal Mycobacterium avium infections in patients with AIDS: variations in antimicrobial susceptibilities of different strains of M. avium isolated from the same patient.

    PubMed Central

    von Reyn, C F; Jacobs, N J; Arbeit, R D; Maslow, J N; Niemczyk, S

    1995-01-01

    Broth microdilution MICs were determined for pairs of strains isolated from five AIDS patients with polyclonal Mycobacterium avium infection. Four (80%) of the five patients were infected simultaneously with strains having different antimicrobial susceptibility patterns. These findings have implications for the interpretation of susceptibility data in M. avium prophylaxis and treatment trials. PMID:7790424

  12. Elucidation of Antimicrobial Susceptibility Profiles and Genotyping of Salmonella enterica Isolates from Clinical Cases of Salmonellosis in New Mexico in 2008

    PubMed Central

    Smith, Kenneth P.; George, Jeffy; Cadle, Kathleen M.; Kumar, Sanath; Aragon, Steven J.; Hernandez, Ricardo L.; Jones, Suzanna E.; Floyd, Jody L.; Varela, Manuel F.

    2010-01-01

    In this study, we investigated the antimicrobial susceptibility profiles and the distribution of some well known genetic determinants of virulence in clinical isolates of Salmonella enterica from New Mexico. The minimum inhibitory concentrations (MICs) for various antimicrobials were determined by using the E-test strip method according to CLSI guidelines. Virulence genotyping was performed by polymerase chain reaction (PCR) using primers specific for known virulence genes of Salmonella enterica. Of 15 isolates belonging to 11 different serovars analyzed, one isolate of Salmonella Typhimurium was resistant to multiple drugs namely ampicillin, amoxicillin / clavulanic acid, chloramphenicol and tetracycline, that also harbored class 1 intergron, blaTEM encoding genes for β-lactamase, chloramphenicol acetyl transferase (cat1), plus floR, tet(C) and tet(G). This strain was phage typed as DT104. PCR analysis revealed the presence of invA, hilA, stn, agfA and spvR virulence genes in all the isolates tested. The plasmid-borne pefA gene was absent in 11 isolates, while 5 isolates lacked sopE. One isolate belonging to serogroup E4 (Salmonella Sombre) was devoid of multiple virulence genes pefA, iroB, shdA and sopE. These results demonstrate that clinical Salmonella serotypes from New Mexico used here are predominantly sensitive to multiple antimicrobial agents, but vary in their virulence genotypes. Information on antimicrobial sensitivity and virulence genotypes will help in understanding the evolution and spread of epidemic strains of Salmonella enterica in the region of study. PMID:20514366

  13. [Susceptibility of spore-forming butyric acid bacteria to antimicrobial agents].

    PubMed

    Kaneko, Naofumi; Nakayama, Tomohiro; Ichikawa, Nobuhiro

    2012-01-01

    Antimicrobial agents occasionally cause certain adverse effects, such as diarrhea and loose stool, by altering the composition of the intestinal flora. Antibiotic-resistant lactic acid bacteria are used to prevent these adverse effects. Although these bacteria are not resistant to several recently introduced antimicrobial agents, bacterial preparations are still sometimes prescribed concomitantly with these antimicrobial agents. In this study, we investigated whether the administration of the spore-forming butyric acid bacteria Clostridium butyricum improves the adverse clinical effects by preventing diarrhea. Inhibition of C. butyricum growth was observed with 17 of the 20 antimicrobial agents used. However, dilution of 11 of these 17 agents resulted in the regrowth of C. butyricum. These results suggest that C. butyricum may survive exposure to several antibiotic agents by forming spores. Further, a decrease in the antimicrobial agent concentration in the gastrointestinal tract permits the vegetative growth of C. butyricum, which functions as a probiotic. PMID:22790032

  14. Improved method for azole antifungal susceptibility testing.

    PubMed Central

    Gordon, M A; Lapa, E W; Passero, P G

    1988-01-01

    A reproducible method is described for the determination of the MICs of ketoconazole, miconazole, fluconazole, and itraconazole with sharp endpoints when employed with either yeasts or molds. A semisolid medium is used with controlled pH and standardized inoculum. The time of reading results is a critical factor in the conduct of this test. The medium is simple to prepare and has a relatively long refrigerator shelf life in a user-ready state, requiring only the addition of a freshly prepared inoculum after restoration to room temperature. Images PMID:2846651

  15. Prevalence of putative virulence factors and antimicrobial susceptibility of Enterococcus faecalis isolates from patients with dental Diseases

    PubMed Central

    Salah, Randa; Dar-Odeh, Najla; Abu Hammad, Osama; Shehabi, Asem A

    2008-01-01

    Background This study investigated the prevalence of Enterococcus faecalis, its putative virulence factors and antimicrobial susceptibility in individuals with and without dental diseases. A total of 159 oral rinse specimens were collected from patients (n = 109) suffering from dental diseases and healthy controls (n = 50). Results E. faecalis was detected using only culture in 8/109 (7.3%) of the patients with various types of dental diseases, whereas no E. faecalis was found in the healthy controls weather using both culture and PCR. Phenotype characterizations of the 8 E. faecalis isolates indicated that 25% of the isolates produced haemolysin and 37.5% produced gelatinase. Most important virulence genes; collagen binding protein (ace) and endocarditis antigen (efaA) were present in all 8 E. faecalis isolates, while haemolysin activator gene (cylA) was detected only in 25% of isolates, and all isolates were negative for esp gene. All E. faecalis isolates were 100% susceptible to ampicillin, chloramphenicol, ciprofloxacin, vancomycin, and teicoplanin, and to less extent to erythromycin (62.5%). Conclusion This study shows that all E. faecalis isolates were recovered only from patients with dental diseases especially necrotic pulps, and all isolates carried both collagen binding protein and endocarditis antigen genes and highly susceptible to frequently used antimicrobial drugs in Jordan. PMID:18513445

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

    PubMed

    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

  17. Toxinotyping and antimicrobial susceptibility of enterotoxigenic Clostridium perfringens isolates from mutton, beef and chicken meat.

    PubMed

    Khan, Madiha; Nazir, Jawad; Anjum, Aftab Ahmad; Ahmad, Mansur-Ud-Din; Nawaz, Muhammad; Shabbir, Muhammad Zubair

    2015-08-01

    A total of 300 meat samples comprising mutton, beef, and chicken meat (n = 100) collected from either local butcher shops or large meat outlets situated at various areas of Lahore City located in Punjab province of Pakistan were tested for the isolation of Clostridium perfringens. Prevalence of the organism was highest in the chicken (6 %) followed by mutton (5 %) and beef (1 %). Contamination level was high (10/150) in the samples collected from local butcher shops in comparison to the samples collected from large meat outlets (2/150). All of the raw meat samples were negative for the presence of alpha, beta and epsilon toxins of C. perfringens as detected through ELISA. Out of a total number of 12 isolates only half were capable of producing enterotoxins when cultured in trypticase glucose yeast (TGY) broth. Toxinotyping of the isolates showed that 3 were of type A while one each of the remaining three belonged to type B, C, and D. Antibiotic susceptibility testing of the toxin producing isolates revealed that C. perfringens were susceptible to chloramphenicol, ciprofloxacin, metronidazole, and ceftriaxone. All of the other drugs were relatively less effective with a least activity of amoxicillin against the isolates. PMID:26243960

  18. Are E-test and Vitek2 good choices for tigecycline susceptibility testing when comparing broth microdilution for MDR and XDR Acinetobacter baumannii?

    PubMed

    Grandesso, Stefano; Sapino, Barbara; Amici, Gianpaolo; Mazzucato, Sandra; Solinas, Maria; Gion, Massimo

    2014-10-01

    This study reports the results of antimicrobial susceptibility testing of 10 MDR and 74 XDR Acinetobacter bauman- nii clinical isolates from our hospital routine. We used three different methods: two automated systems (Sensititre and VITEK 2) and one standardized manual method (E-test). Since many published papers refer to in vitro tests performed by E-test, the aim of this study was to test if this method is reliable for testing tigecycline. The results obtained show that E-test significantly overestimates the MIC of the broth microdilution (reference test), thus ob- taining a significant number of major errors (resistant instead of sensitive). VITEK 2 also shows the same problem, but it is less critical. We therefore conclude that these methods do not seem to be very reliable in the performance of susceptibility testing of MDR and XDR Acinetobacter baumannii against tigecycline. PMID:25387287

  19. In vitro susceptibility of e.faecalis and c.albicans isolates from apical periodontitis to common antimicrobial agents, antibiotics and antifungal medicaments

    PubMed Central

    Yoldas, Oguz; Yilmaz, Sehnaz; Akcimen, Beril; Seydaoglu, Gulsah; Kipalev, Arzu; Koksal, Fatih

    2012-01-01

    The aim of this study was to evaluate in vitro antimicrobial activity of 4 antibiotic agents (for E.faecalis) and 4 antifungal agents (for C.albicans) by agar dilution method. Additionally, modified strip diffusion method was used for detection of in vitro antimicrobial activities of 5% NaOCl, 2.5% NaOCl, 17% EDTA and 2% CHX and agar diffusion method for detection of in vitro susceptibilities of three intracanal medicaments for 18 E.faecalis and 18 C.albicans isolates from primary and secondary root canal infection. Isolates were recovered from 231 endodontic samples of patients, with the need of root canal treatment and retreatment. All tested E.faecalis isolates showed resistance to antibiotics. For irrigation solutions, 2% CHX was more effective in eliminating E.faecalis but 5% NaOCl showed larger inhibition zone than 2.5% NaOCl, 17% EDTA and 2% CHX. For intracanal medication, Ca(OH)2-CHX worked efficiently in killing E.faecalis isolates compared to Ca(OH)2-Steril saline solution, Ca(OH)2-Glycerin. For C.albicans, 18 isolates were susceptible to amphotericin B, nistatin, fluconazole but showed resistance to ketoconazole. 5% NaOCl was more effective in eliminating and produced larger inhibition zone compared to 2.5% NaOCl, 17% EDTA and 2% CHX. Ca(OH)2-Glycerin intracanal medication was better in eliminating C.albicans isolates and produced larger inhibition zone compared to other Ca(OH)2 medicaments. Key words:E.faecalis, C.albicans, antimicrobial, antibiotic, antifungal. PMID:24558517

  20. Prevalence, bacterial causes, and antimicrobial susceptibility profile of mastitis isolates from cows in large-scale dairy farms of Northern Ethiopia.

    PubMed

    Haftu, Rgbe; Taddele, Habtamu; Gugsa, Getachew; Kalayou, Shewit

    2012-10-01

    The study was undertaken to determine the prevalence of bovine mastitis, isolate mastitis causing bacteria, assess the association of some risk factors, and determine the antibiotic resistance pattern of bacterial isolates in cows in large-scale dairy farms of Northern Ethiopia. A total of 305 lactating and nonlactating cows were included in the present study. The overall prevalence of clinical and subclinical mastitis was 3.6 and 33.8 %, respectively. The quarter level prevalence was 15.4 %; from which, 11.9 and 1.1 % were subclinical form and blind teat, respectively, while the remaining 2.4 % were of clinical form. Staphylococcus aureus accounted for 36 % of the isolates followed by Escherichia coli (27.3 %). Risk factors including age (p < 0.001), parity (p < 0.001), and lactation stage (p = 0.02) showed significant association with the occurrence of mastitis. Higher prevalence was observed in both groups of older cows (i.e., 6-9 years (odds ratio (OR) = 4.65, 95 % confidence interval (CI) = 2.74-7.89) and >9 years (OR = 3.63, 95 % CI = 1.42-9.25)), cows with four to seven calves (OR = 3.39, 95 % CI = 2.06-5.60), and cows in late lactation stage (OR = 3.79, 95 % CI = 1.64-8.75). In multivariable logistic regression analysis, age (p = 0.005) and lactation stage (p = 0.027) showed statistically significant association with the occurrence of mastitis. The antimicrobial susceptibility pattern showed high susceptibility of S. aureus to nalidixic acid (82.4 %) followed by chloramphenicol (58.8 %); however, these species were resistant to the rest of the antimicrobials tested. Highest resistance was observed against clindamycin and ampicillin. Coliform bacteria (E. coli and Klebsiella pneumoniae) showed resistance to most of the antimicrobials used. Detailed investigation is needed to identify the interplay of managemental and environmental risk factors to design appropriate control measures. PMID:22476790

  1. Analysis of quorum sensing-dependent virulence factor production and its relationship with antimicrobial susceptibility in Pseudomonas aeruginosa respiratory isolates.

    PubMed

    Karatuna, O; Yagci, A

    2010-12-01

    Pseudomonas aeruginosa is an opportunistic pathogen causing severe respiratory infections. The pathogenesis of these infections is multifactorial and the production of many virulence factors is regulated by quorum sensing (QS), a cell-to-cell communication mechanism. The two well defined QS systems in P. aeruginosa, the las and rhl systems, rely on N-acyl homoserine lactone signal molecules, also termed autoinducers. We assessed the activity of QS-dependent virulence factors (including elastase, alkaline protease, pyocyanin and biofilm production) in respiratory isolates of P. aeruginosa and their relationship with antimicrobial susceptibility. We identified sixteen isolates displaying impaired phenotypic activity; among them, eleven isolates were also defective in autoinducer production, and therefore considered QS-deficient. Six of the QS-deficient isolates failed to amplify one or more of the four QS regulatory genes (lasI, lasR, rhlI, rhlR) with PCR: one isolate was negative for rhlR, two isolates were negative for rhlI and rhlR and three isolates were negative for all four genes. The isolates that were negative for virulence factor production were generally less susceptible to the antimicrobials and statistically significant correlations were observed between the lack of elastase production and resistance to piperacillin and ceftazidime; between failure in alkaline protease production and resistance to tobramycin, piperacillin, piperacillin-tazobactam, cefepime, imipenem and ciprofloxacin; and between failure in pyocyanin production and resistance to amikacin, tobramycin, ceftazidime, ciprofloxacin and ofloxacin. The results obtained indicate that, despite the pivotal role of QS in the pathogenesis of P. aeruginosa respiratory infections, QS-deficient strains are still capable of causing infections and tend to be less susceptible to antimicrobials. PMID:20132256

  2. Characterization of Antimicrobial Susceptibility and Its Association with Virulence Genes Related to Adherence, Invasion, and Cytotoxicity in Campylobacter jejuni and Campylobacter coli Isolates from Animals, Meat, and Humans.

    PubMed

    Lapierre, Lisette; Gatica, María A; Riquelme, Víctor; Vergara, Constanza; Yañez, José Manuel; San Martín, Betty; Sáenz, Leonardo; Vidal, Maricel; Martínez, María Cristina; Araya, Pamela; Flores, Roberto; Duery, Oscar; Vidal, Roberto

    2016-07-01

    The aim of this research was to statistically analyze the association between antimicrobial susceptibility/resistance to erythromycine, gentamicin, ciprofloxacin, and tetracycline and 11 virulence genes associated with adherence, invasion, and cytotoxicity in 528 isolates of Campylobacter coli and Campylobacter jejuni obtained from retail meat and fecal samples from food-producing animals and human patients. A high percentage of Campylobacter strains were resistant to antimicrobials, specifically ciprofloxacin and tetracycline. Moreover, we observed a wide distribution of virulence genes within the analyzed strains. C. jejuni strains were more susceptible to antimicrobials, and showed greater number of virulence genes than C. coli strains. Genes related to invasion capability, such as racR, ciaB, and pldA, were associated with antimicrobial-susceptible strains in both species. The genes cdtA and dnaJ, a citotoxin unit and an adherence-related gene, respectively, were associated with antimicrobial-resistant strains in both species. In conclusion, Campylobacter strains show a statistically significant association between antimicrobial susceptibility and the presence of virulence genes. PMID:26779841

  3. Overall decrease in the susceptibility of Mycoplasma bovis to antimicrobials over the past 30 years in France.

    PubMed

    Gautier-Bouchardon, Anne V; Ferré, Séverine; Le Grand, Dominique; Paoli, Agnès; Gay, Emilie; Poumarat, François

    2014-01-01

    Mycoplasma (M.) bovis is frequently implicated in respiratory diseases of young cattle worldwide. Today, to combat M. bovis in Europe, only antimicrobial therapy is available, but often fails, leading to important economical losses. The antimicrobial susceptibility of M. bovis is not covered by antimicrobial resistance surveillance networks. The objectives of this study were to identify resistances that were acquired over the last 30 years in France and to determine their prevalence within contemporary strains. The minimum inhibition concentration (MIC) values of 12 antimicrobials, considered active on M. bovis, were compared, using an agar dilution method, between 27 and 46 M. bovis isolates respectively obtained in 1978-1979 and in 2010-2012 from 73 distinct respiratory disease outbreaks in young cattle all over France. For eight antimicrobials, resistances were proven to be acquired over the period and expressed by all contemporary strains. The increase of the MIC value that inhibited 50% of the isolates (MIC50) was: i) substantial for tylosin, tilmicosin, tulathromycin and spectinomycin, from 2 to >64, 2 to >128, 16 to 128 and 4 to >64 µg/mL, respectively, ii) moderate for enrofloxacin, danofloxacin, marbofloxacin and oxytetracycline, from 0.25 to 0.5, 0.25 to 0.5, 0.5 to 1, 32 to >32 µg/mL, respectively. No differences were observed for gamithromycin, tildipirosin, florfenicol and valnemulin with MIC50 of 128, 128, 8, <0.03 µg/mL, respectively. If referring to breakpoint MIC values published for respiratory bovine pathogens, all contemporary isolates would be intermediate in vivo for fluoroquinolones and resistant to macrolides, oxytetracycline, spectinomycin and florfenicol. PMID:24503775

  4. Overall Decrease in the Susceptibility of Mycoplasma bovis to Antimicrobials over the Past 30 Years in France

    PubMed Central

    Gautier-Bouchardon, Anne V.; Ferré, Séverine; Le Grand, Dominique; Paoli, Agnès; Gay, Emilie; Poumarat, François

    2014-01-01

    Mycoplasma (M.) bovis is frequently implicated in respiratory diseases of young cattle worldwide. Today, to combat M. bovis in Europe, only antimicrobial therapy is available, but often fails, leading to important economical losses. The antimicrobial susceptibility of M. bovis is not covered by antimicrobial resistance surveillance networks. The objectives of this study were to identify resistances that were acquired over the last 30 years in France and to determine their prevalence within comtemporary strains. The minimum inhibition concentration (MIC) values of 12 antimicrobials, considered active on M. bovis, were compared, using an agar dilution method, between 27 and 46 M. bovis isolates respectively obtained in 1978–1979 and in 2010–2012 from 73 distinct respiratory disease outbreaks in young cattle all over France. For eight antimicrobials, resistances were proven to be acquired over the period and expressed by all contemporary strains. The increase of the MIC value that inhibited 50% of the isolates (MIC50) was: i) substantial for tylosin, tilmicosin, tulathromycin and spectinomycin, from 2 to >64, 2 to >128, 16 to 128 and 4 to >64 µg/mL, respectively, ii) moderate for enrofloxacin, danofloxacin, marbofloxacin and oxytetracycline, from 0.25 to 0.5, 0.25 to 0.5, 0.5 to 1, 32 to >32 µg/mL, respectively. No differences were observed for gamithromycin, tildipirosin, florfenicol and valnemulin with MIC50 of 128, 128, 8, <0.03 µg/mL, respectively. If referring to breakpoint MIC values published for respiratory bovine pathogens, all contemporary isolates would be intermediate in vivo for fluoroquinolones and resistant to macrolides, oxytetracycline, spectinomycin and florfenicol. PMID:24503775

  5. Antimicrobial susceptibilities of Escherichia coli isolates as agents of community-acquired urinary tract infection (2008–2014)

    PubMed Central

    Yılmaz, Nisel; Ağuş, Neval; Bayram, Arzu; Şamlıoğlu, Pınar; Şirin, M. Cem; Derici, Yeşer Karaca; Hancı, Sevgi Yılmaz

    2016-01-01

    Objective Urinary tract infections (UTIs) are among the most frequently seen community-acquired infections worldwide. E. coli causes 90% of urinary system infections. To guide the empirical therapy, the resistance pattern of E. coli responsible for community-acquired UTI was evaluated throughout a seven-year period in this study. Material and methods The urine cultures of patients with urinary tract infections admitted to outpatient clinics between 1st January 2008 and 31st December 2014 were analyzed. Presence of ≥105 colony-forming units/mL in urine culture media was considered as significant for UTI. Isolated bacteria were identified by standard laboratory techniques or automated system VITEK2 (BioMerieux, France) and BD PhoenixTM 100 (BD, USA), as required. Antibiotic susceptibility testing was performed by Kirby-Bauer disk diffusion method using Clinical Laboratory Standard Institute (CLSI) criteria. Results A total of 13281 uropathogens were isolated. Overall E. coli accounted for 8975 (67%) of all isolates. Resistance rates of E. coli to antimicrobial agents was demonstrated to be as follows: ampicillin 66.9%, cefazolin 30.9%, cefuroxime 30.9%, ceftazidime 14.9%, cefotaxime 28%, cefepime 12%, amoxicillin-clavulanic acid 36.9%, trimethoprim-sulfamethoxazole (TMP-SXT) 20%, ciprofloxacin 49.9%, amikacin 0.3%, gentamycin 24%, nitrofurantoin 0.9%, and fosfomycin 4.3%. There was no resistance to imipenem nor meropenem. The frequency of ESBL-producing E. coli strains was 24%. Conclusion It is concluded that fosfomycin and nitrofurantoin are appropriate empirical therapy for community-acquired UTI empirical therapy, but the fluoroquinolones and the TMP-SXT shall not be used in the emprical treatment of UTI at this stage. In conclusion, as resistance rates show regional differences, it is necessary to regularly examine regional resistance rates to determine the appropriate empiric antibiotic treatment and national antibiotic usage policies must be reorganized

  6. Antimicrobial Susceptibility and Plasmid Replicon Typing of Salmonella enterica serovar Kentucky isolates recovered from Broilers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella Kentucky has become the predominate serotype recovered from broiler slaughter in the United States and the prevalence of antimicrobial resistance (AMR) has increased dramatically in this serotype. Relationships between AMR, genotype, and plasmid replicon types were characterized for 600 ...

  7. Rapid method for determination of antimicrobial susceptibilities pattern of urinary bacteria

    NASA Technical Reports Server (NTRS)

    Picciolo, G. L.; Chapelle, E. W.; Barza, M. J.; Weinstein, L.; Tuttle, S. A.; Vellend, H.

    1975-01-01

    Method determines bacterial sensitivity to antimicrobial agents by measuring level of adenosine triphosphate remaining in the bacteria. Light emitted during reaction of sample with a mixture of luciferase and luciferin is measured.

  8. Antibacterial susceptibility of plaque bacteria.

    PubMed

    Newman, M G; Hulem, C; Colgate, J; Anselmo, C

    1979-07-01

    Selected anaerobic, capnophilic and facultative bacteria isolated from patients with various forms of periodontal health and disease were tested for their susceptibility to antibiotics and antimicrobial agents. Specific bactericidal and minimum inhibitory concentrations were compared to disc zone diameters, thereby generating new standards for the potential selection of antimicrobial agents. PMID:286720

  9. Susceptibility of bacterial etiological agents to commonly-used antimicrobial agents in children with sepsis at the Tamale Teaching Hospital

    PubMed Central

    2013-01-01

    Background Bloodstream infections in neonates and infants are life-threatening emergencies. Identification of the common bacteria causing such infections and their susceptibility patterns will provide necessary information for timely intervention. This study is aimed at determining the susceptibilities of bacterial etiological agents to commonly-used antimicrobial agents for empirical treatment of suspected bacterial septicaemia in children. Methods This is a hospital based retrospective analysis of blood cultures from infants to children up to 14 years of age with preliminary diagnosis of sepsis and admitted to the Neonatal Intensive Care Unit (NICU) and Paediatric Wards of the Teaching Hospital Tamale from July 2011 to January 2012. Results Out of 331 blood specimens cultured, the prevalence of confirmed bacterial sepsis was 25.9% (86/331). Point prevalence for confirmed cases from NICU was 44.4% (28/63) and 21.6% (58/268) from the Paediatric ward. Gram positive cocci (GPC) were the predominant isolates with Coagulase positive (32.2%) and Coagulase-negative (28.7%) Staphylococci accounting for 60.9% of the total isolates. Gram negative rods (GNR) comprised 39.1% of all isolates with Klebsiella, E.coli and Salmonella being the most common organisms isolated. Klebsiella was the most frequent GNR from the NICU and Salmonella typhi was predominantly isolated from the paediatric ward. Acinetobacter showed 100.0% susceptibility to Ceftriaxone and Cefotaxime but was resistant (100.0%) to Ampicillin, Tetracycline and Cotrimoxazole. Escherichia coli and Klebsiella were 80.0% and 91.0% susceptible to Ceftriaxone and Cefotaxime respectively. Klebsiella species showed 8.3% susceptibility to Tetracycline but was resistant to Ampicillin and Cotrimoxazole. Escherichia coli showed 40.0% susceptibility to Ampicillin, Chloramphenicol and Cotrimoxazole; 20.0% susceptibility to Tetracycline and 80.0% susceptible to Gentamicin and Cefuroxime. Coagulase negative Staphylococci was

  10. Population genetic testing for cancer susceptibility: founder mutations to genomes.

    PubMed

    Foulkes, William D; Knoppers, Bartha Maria; Turnbull, Clare

    2016-01-01

    The current standard model for identifying carriers of high-risk mutations in cancer-susceptibility genes (CSGs) generally involves a process that is not amenable to population-based testing: access to genetic tests is typically regulated by health-care providers on the basis of a labour-intensive assessment of an individual's personal and family history of cancer, with face-to-face genetic counselling performed before mutation testing. Several studies have shown that application of these selection criteria results in a substantial proportion of mutation carriers being missed. Population-based genetic testing has been proposed as an alternative approach to determining cancer susceptibility, and aims for a more-comprehensive detection of mutation carriers. Herein, we review the existing data on population-based genetic testing, and consider some of the barriers, pitfalls, and challenges related to the possible expansion of this approach. We consider mechanisms by which population-based genetic testing for cancer susceptibility could be delivered, and suggest how such genetic testing might be integrated into existing and emerging health-care structures. The existing models of genetic testing (including issues relating to informed consent) will very likely require considerable alteration if the potential benefits of population-based genetic testing are to be fully realized. PMID:26483301

  11. The Activity of Antimicrobial Surfaces Varies by Testing Protocol Utilized

    PubMed Central

    Campos, Matias D.; Zucchi, Paola C.; Phung, Ann; Leonard, Steven N.; Hirsch, Elizabeth B.

    2016-01-01

    Background Contaminated hospital surfaces are an important source of nosocomial infections. A major obstacle in marketing antimicrobial surfaces is a lack of efficacy data based on standardized testing protocols. Aim We compared the efficacy of multiple testing protocols against several “antimicrobial” film surfaces. Methods Four clinical isolates were used: one Escherichia coli, one Klebsiella pneumoniae, and two Staphylococcus aureus strains. Two industry methods (modified ISO 22196 and ASTM E2149), a “dried droplet”, and a “transfer” method were tested against two commercially available antimicrobial films, one film in development, an untreated control, and a positive (silver) control film. At 2 (only ISO) and 24 hours following inoculation, bacteria were collected from film surfaces and enumerated. Results Compared to untreated films in all protocols, there were no significant differences in recovery on either commercial brand at 2 or 24 hours after inoculation. The silver surface demonstrated significant microbicidal activity (mean loss 4.9 Log10 CFU/ml) in all methods and time points with the exception of 2 hours in the ISO protocol and the transfer method. Using our novel droplet method, no differences between placebo and active surfaces were detected. The surface in development demonstrated variable activity depending on method, organism, and time point. The ISO demonstrated minimal activity at 2 hours but significant activity at 24 hours (mean 4.5 Log10 CFU/ml difference versus placebo). The ASTEM protocol exhibited significant differences in recovery of staphylococci (mean 5 Log10 CFU/ml) but not Gram-negative isolates (10 fold decrease). Minimal activity was observed with this film in the transfer method. Conclusions Varying results between protocols suggested that efficacy of antimicrobial surfaces cannot be easily and reproducibly compared. Clinical use should be considered and further development of representative methods is needed. PMID

  12. Bacterial profile of urinary tract infection and antimicrobial susceptibility pattern among pregnant women attending at Antenatal Clinic in Dil Chora Referral Hospital, Dire Dawa, Eastern Ethiopia

    PubMed Central

    Derese, Behailu; Kedir, Haji; Teklemariam, Zelalem; Weldegebreal, Fitsum; Balakrishnan, Senthilkumar

    2016-01-01

    Purpose The aim of this study was to determine the bacterial profile of urinary tract infection (UTI) and antimicrobial susceptibility pattern among pregnant women attending at antenatal clinic in Dil Chora Referral Hospital, Dire Dawa, Eastern Ethiopia. Patients and methods An institutional-based cross-sectional study was conducted from February 18, 2015 to March 25, 2015. Clean-catch midstream urine specimens were collected from 186 pregnant women using sterile containers. Then, culture and antimicrobial susceptibility tests were performed by standard disk diffusion method. Patient information was obtained using pretested structured questionnaire. Data were entered and cleaned using EpiData Version 3 and then exported to Statistical Package for Social Science (Version 16) for further analysis. Results The prevalence of significant bacteriuria was 14%. Gram-negative bacteria were more prevalent (73%). Escherichia coli (34.6%), coagulase-negative staphylococci (19.2%), Pseudomonas aeruginosa (15.4%), and Klebsiella spp. (11.5%) were common bacterial isolates,