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Ronald N. Jones - One of the best experts on this subject based on the ideXlab platform.
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determination of Disk Diffusion and mic quality control guidelines for solithromycin a novel fluoroketolide antibacterial against neisseria gonorrhoeae
Journal of Clinical Microbiology, 2015Co-Authors: Stefan Riedel, James E. Ross, David J Farrell, Robert K Flamm, Ronald N. JonesAbstract:This solithromycin quality control study was performed to establish quality control (QC) ranges for the N. gonorrhoeae ATCC 49226 control strain for MIC agar dilution testing (AD) and zones by Disk Diffusion testing (DD). The following ranges were established: AD, 0.03 to 0.25 μg/ml, and DD, 33 to 43 mm. In January 2015, the CLSI Subcommittee on Antimicrobial Susceptibility Testing approved these ranges, which will be important when evaluating solithromycin against clinical isolates of N. gonorrhoeae.
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Disk Diffusion and mic quality control ranges for bc 3205 and bc 3781 two novel pleuromutilin antibiotics
Journal of Clinical Microbiology, 2012Co-Authors: James E. Ross, Helio S. Sader, Zrinka Ivezicschoenfeld, Susanne Paukner, Ronald N. JonesAbstract:ABSTRACT MIC and Disk Diffusion quality control (QC) ranges were established for two new pleuromutilin antimicrobials (BC-3205 and BC-3781) in an eight-laboratory study performed according to Clinical and Laboratory Standards Institute M23-A3 guidelines. Staphylococcus aureus ATCC 29213 and 25923, Streptococcus pneumoniae ATCC 49619, and Haemophilus influenzae ATCC 4927 strains were evaluated. The proposed QC ranges would aid clinical laboratories in testing these compounds following their development for treatment of respiratory and cutaneous infections.
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Determination of Disk Diffusion and MIC Quality Control Ranges for GSK1322322: A Novel Peptide Deformylase Inhibitor
Journal of clinical microbiology, 2011Co-Authors: James E. Ross, Nicole E. Scangarella-oman, Linda A. Miller, Helio S. Sader, Ronald N. JonesAbstract:ABSTRACT GSK1322322 is a novel peptide deformylase inhibitor in the early phase of development for treatment of complicated bacterial skin and skin structure infection and hospitalized community-acquired pneumonia. This quality control (QC) study was performed to establish broth microdilution and Disk Diffusion QC ranges for strains Staphylococcus aureus ATCC 29213 (MIC range, 1 to 4 μg/ml), Haemophilus influenzae ATCC 49247 (MIC and Disk Diffusion zone diameter ranges, 0.5 to 4 μg/ml and 20 to 28 mm, respectively), Streptococcus pneumoniae ATCC 49619 (MIC and Disk Diffusion zone diameter ranges, 0.12 to 0.5 μg/ml and 23 to 30 mm, respectively), and S. aureus ATCC 25923 (Disk Diffusion zone diameter range, 18 to 26 mm). These ranges are crucial for evaluating GSK1322322 potency as it progresses through clinical trials.
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development of anidulafungin for Disk Diffusion susceptibility testing against candida spp
Diagnostic Microbiology and Infectious Disease, 2007Co-Authors: Ronald N. Jones, Jeffrey T Kirby, S A Messer, Daniel J SheehanAbstract:Abstract A Disk Diffusion (DD) method has been standardized by the Clinical and Laboratory Standards Institute (M44-A) to test Candida susceptibilities for some azoles (fluconazole and voriconazole). The DD method using anidulafungin, a new echinocandin, was initially developed here using Candida spp. (75 strains) and candidate anidulafungin Disk concentrations of 1, 2, 5, and 10 μg with or without dimethyl sulfoxide (DMSO) (0.05–1%) and with or without polysorbate 80 (P-80, 0.002–2%). The 2-μg Disks (with 1% DMSO and 0.1% P-80) produced acceptable correlation statistics ( r = 0.84–0.85 ) when compared with reference MIC results, and this Disk was optimal for testing all Candida spp. Good separation of Candida parapsilosis (least anidulafungin-susceptible species) from the more susceptible yeast species and a potential susceptibility breakpoint near the preferred reproducible zone diameter of ≥15 mm were achieved for all tested yeast species.
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Disk Diffusion susceptibility test development for the new glycylcycline, GAR-936.
Diagnostic microbiology and infectious disease, 1999Co-Authors: Ronald N. JonesAbstract:The in vitro activity of GAR-936, a new semisynthetic glycylcycline, was evaluated in comparison with two tetracyclines and the Disk Diffusion susceptibility test was assessed. Nearly 700 recent clinical isolates were tested by reference broth microdilution and Disk Diffusion (two Disk contents) methods. Among the Enterobacteriaceae, GAR-936 was generally two- to 16-fold more active than other tetracyclines. All enteric bacilli MIC90 results were or = 8 micrograms/mL). GAR-936 demonstrated excellent activity against all Gram-positive cocci with Enterococcus spp. (including vancomycin-resistant isolates) inhibited at 0.25 microgram/mL (GAR-936 MIC90, 0.12 or 0.25 microgram/mL) and the oxacillin-resistant Staphylococcus aureus strains were inhibited at < or = 0.25 microgram/mL. GAR-936 demonstrated good potency against several non-fermentative bacteria, but possessed limited activity against Pseudomonas aeruginosa (MIC50, 8 micrograms/mL). In vitro susceptibility test methods were developed (Disk Diffusion versus reference MIC results) and tentative breakpoints were proposed. Using susceptibility criteria of either < or = 2 or < or = 4 micrograms/mL, GAR-936 in vitro susceptibility tests demonstrated rare significant serious inter-method discords (< or = 1.2%) and an absolute agreement between test results of 92.3 to 96.2%. These results indicate that GAR-936 has potent in vitro activity against a wide range of clinically important rapidly growing pathogenic bacteria, and that this novel glycylcycline candidate for clinical use should be further developed.
Gunnar Kahlmeter - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial susceptibility testing of kingella kingae with broth microdilution and Disk Diffusion using eucast recommended media
Clinical Microbiology and Infection, 2017Co-Authors: Erika Matuschek, Gunnar Kahlmeter, Jenny Ahman, Pablo YagupskyAbstract:Abstract Objectives Increasing use of improved culture techniques and sensitive nucleic acid amplification assays have resulted in recognition of Kingella kingae as an important cause of invasive infections in young children, especially in septic arthritis, osteomyelitis, bacteraemia, and endocarditis. In 2016, EUCAST established clinical MIC breakpoints for K. kingae (published in EUCAST Clinical Breakpoint Tables v 7.0, 2017). The present study was carried out to produce MIC-zone diameter correlations for K. kingae on an international collection of isolates, with the aim of suggesting zone diameter breakpoints corresponding to the clinical MIC breakpoints. Methods Antimicrobial susceptibility testing was performed for 18 clinically relevant agents on a collection of 159 clinical isolates of K. kingae . Broth microdilution MIC determination and Disk Diffusion were performed according to EUCAST recommendations for fastidious organisms. Results The correlation between MICs and zone diameters was good for all agents with EUCAST breakpoints for K. kingae . β-lactamase was detected in 41 isolates (26%) and these isolates were resistant to aminopenicillins. These isolates were also resistant to trimethoprim-sulfamethoxazole. Resistance to tetracyclines was detected in 8% of all isolates. All resistant isolates were correctly categorized for these agents with the proposed zone diameter breakpoints. One isolate, resistant to erythromycin but susceptible to other macrolides, was categorized as susceptible with erythromycin Disk Diffusion. No resistance was detected for the cephalosporins, carbapenems, and fluoroquinolones tested. Conclusion Based on the results in this study, zone diameter breakpoints for K. kingae calibrated to EUCAST clinical MIC breakpoints were proposed and approved by EUCAST.
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development of a pefloxacin Disk Diffusion method for detection of fluoroquinolone resistant salmonella enterica
Journal of Clinical Microbiology, 2015Co-Authors: Robert Skov, Erika Matuschek, Maria Sjolundkarlsson, Jenny Ahman, Andreas Petersen, Marc Stegger, Mia Torpdahl, Gunnar KahlmeterAbstract:ABSTRACT Fluoroquinolones (FQs) are among the drugs of choice for treatment of Salmonella infections. However, fluoroquinolone resistance is increasing in Salmonella due to chromosomal mutations in the quinolone resistance-determining regions (QRDRs) of the topoisomerase genes gyrA, gyrB, parC, and parE and/or plasmid-mediated quinolone resistance (PMQR) mechanisms including qnr variants, aac(6′)-Ib-cr, qepA, and oqxAB. Some of these mutations cause only subtle increases in the MIC, i.e., MICs ranging from 0.12 to 0.25 mg/liter for ciprofloxacin (just above the wild-type MIC of ≤0.06 mg/liter). These isolates are difficult to detect with standard ciprofloxacin Disk Diffusion, and plasmid-mediated resistance, such as qnr, is often not detected by the nalidixic acid screen test. We evaluated 16 quinolone/fluoroquinolone Disks for their ability to detect low-level-resistant Salmonella enterica isolates that are not serotype Typhi. A total of 153 Salmonella isolates characterized for the presence (n = 104) or absence (n = 49) of gyrA and/or parC topoisomerase mutations, qnrA, qnrB, qnrD, qnrS, aac(6′)-Ib-cr, or qepA genes were investigated. All isolates were MIC tested by broth microdilution against ciprofloxacin, levofloxacin, and ofloxacin and by Disk Diffusion using EUCAST or CLSI methodology. MIC determination correctly categorized all isolates as either wild-type isolates (MIC of ≤0.06 mg/liter and absence of resistance genes) or non-wild-type isolates (MIC of >0.06 mg/liter and presence of a resistance gene). Disk Diffusion using these antibiotics and nalidixic acid failed to detect some low-level-resistant isolates, whereas the 5-μg pefloxacin Disk correctly identified all resistant isolates. However, pefloxacin will not detect isolates having aac(6′)-Ib-cr as the only resistance determinant. The pefloxacin Disk assay was approved and implemented by EUCAST (in 2014) and CLSI (in 2015).
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performance of the eucast Disk Diffusion method the clsi agar screen method and the vitek 2 automated antimicrobial susceptibility testing system for detection of clinical isolates of enterococci with low and medium level vanb type vancomycin resistance a multicenter study
Journal of Clinical Microbiology, 2014Co-Authors: Gunnar Kahlmeter, Bjorg Haldorsen, Arnfinn Sundsfjord, Christian G Giske, Erika Matuschek, Kristin Hegstad, Kristian Schonning, Truls Michael LeegaardAbstract:Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n=28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n=12) and Enterococcus faecium (n=18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n=5), Norwegian (n=13), and Swedish (n=10) laboratories using the EUCAST Disk Diffusion method (n=28) and the CLSI agar screen (n=18) or the Vitek 2 system (bioMerieux) (n=5). The EUCAST Disk Diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P=0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST Disk Diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P<0.0001) or Merck Mueller-Hinton (MH) agar (P=0.027) for the Disk Diffusion assay performed significantly better than did laboratories using BBL MH II medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P=0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST Disk Diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, Disk Diffusion methodology requires that personnel be trained in interpreting zone edges.
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development of the eucast Disk Diffusion antimicrobial susceptibility testing method and its implementation in routine microbiology laboratories
Clinical Microbiology and Infection, 2014Co-Authors: Erika Matuschek, D F J Brown, Gunnar KahlmeterAbstract:Abstract With the support of ESCMID and European countries, EUCAST has developed a Disk Diffusion test with zone diameter breakpoints correlated with the EUCAST clinical MIC breakpoints. The development of the EUCAST Disk Diffusion method and quality control criteria are described, together with guidance on quality control and implementation of the method in clinical microbiology laboratories. The method includes the use of Mueller–Hinton agar without supplements for non-fastidious organisms and with 5% mechanically defibrinated horse blood and 20 mg/L β -NAD for fastidious organisms, a standardized inoculum resulting in confluent growth, an incubation time of 16–20 h, a reading guide on how to read zone diameters on individual species-agent combinations and zone diameter breakpoints calibrated to the EUCAST clinical MIC breakpoints. EUCAST recommendations are described in detail and updated regularly on the EUCAST website (http://www.eucast.org).
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setting interpretive breakpoints for antimicrobial susceptibility testing using Disk Diffusion
International Journal of Antimicrobial Agents, 2011Co-Authors: Goran Kronvall, Christian G Giske, Gunnar KahlmeterAbstract:Antimicrobial susceptibility testing plays a key role in clinical microbiology. The Disk Diffusion test dates back to the 1940s and became standardised from the 1950s, with the International Collaborative Study (ICS) and National Committee for Clinical Laboratory Standards (NCCLS) as the two major standards. Interlaboratory variation of Disk test results was recognised early but has never been dealt with in a satisfactory manner. The error-rate bounded method was described in 1974 and its role is discussed. Species-specific susceptibility interpretation was coined in 1980 for Proteus mirabilis and chloramphenicol. In the late 1970s, more extensive use of species-specific breakpoints was introduced in Lund (Sweden). At the same time, P. Mouton constructed species-specific regression lines and pointed out the difficulties with narrow ranges of minimal inhibitory concentration (MIC) values. A more general use of species-specific regression lines was made possible with single-strain regression analysis, using one well-defined strain tested in Disk Diffusion with a range of Disk contents. This method made it possible to calibrate the Disk test in an individual laboratory. Other methods to achieve such calibration are also described. A recent method, 'MIC-coloured zone diameter histogram-technique', has proven useful for the validation of species-specific interpretive breakpoints. The microbiological breakpoint proposed by Williams in 1990 has experienced a renaissance with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off value (ECOFF). MIC and zone diameter distributions with accompanying ECOFFs for species-antimicrobial combinations are published on the EUCAST website. A method for the reconstruction of wild-type zone diameter populations, namely normalised resistance interpretation, is described. This method can produce resistance figures that are truly comparable between laboratories.
Qijing Zhang - One of the best experts on this subject based on the ideXlab platform.
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comparison of antimicrobial susceptibility testing of campylobacter spp by the agar dilution and the agar Disk Diffusion methods
Journal of Clinical Microbiology, 2007Co-Authors: Tarado Luangtongkum, Teresa Y Morishita, Amna Eltayeb, Aaro J Iso, Qijing ZhangAbstract:The correlation and the level of agreement between the standardized agar dilution and the agar Disk Diffusion methods for antimicrobial susceptibility testing of Campylobacter were investigated. A high-level agreement between the two methods was evident for aminoglycosides and fluoroquinolones, while a low-level agreement was observed for other antibiotics.
Erika Matuschek - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial susceptibility testing of kingella kingae with broth microdilution and Disk Diffusion using eucast recommended media
Clinical Microbiology and Infection, 2017Co-Authors: Erika Matuschek, Gunnar Kahlmeter, Jenny Ahman, Pablo YagupskyAbstract:Abstract Objectives Increasing use of improved culture techniques and sensitive nucleic acid amplification assays have resulted in recognition of Kingella kingae as an important cause of invasive infections in young children, especially in septic arthritis, osteomyelitis, bacteraemia, and endocarditis. In 2016, EUCAST established clinical MIC breakpoints for K. kingae (published in EUCAST Clinical Breakpoint Tables v 7.0, 2017). The present study was carried out to produce MIC-zone diameter correlations for K. kingae on an international collection of isolates, with the aim of suggesting zone diameter breakpoints corresponding to the clinical MIC breakpoints. Methods Antimicrobial susceptibility testing was performed for 18 clinically relevant agents on a collection of 159 clinical isolates of K. kingae . Broth microdilution MIC determination and Disk Diffusion were performed according to EUCAST recommendations for fastidious organisms. Results The correlation between MICs and zone diameters was good for all agents with EUCAST breakpoints for K. kingae . β-lactamase was detected in 41 isolates (26%) and these isolates were resistant to aminopenicillins. These isolates were also resistant to trimethoprim-sulfamethoxazole. Resistance to tetracyclines was detected in 8% of all isolates. All resistant isolates were correctly categorized for these agents with the proposed zone diameter breakpoints. One isolate, resistant to erythromycin but susceptible to other macrolides, was categorized as susceptible with erythromycin Disk Diffusion. No resistance was detected for the cephalosporins, carbapenems, and fluoroquinolones tested. Conclusion Based on the results in this study, zone diameter breakpoints for K. kingae calibrated to EUCAST clinical MIC breakpoints were proposed and approved by EUCAST.
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development of a pefloxacin Disk Diffusion method for detection of fluoroquinolone resistant salmonella enterica
Journal of Clinical Microbiology, 2015Co-Authors: Robert Skov, Erika Matuschek, Maria Sjolundkarlsson, Jenny Ahman, Andreas Petersen, Marc Stegger, Mia Torpdahl, Gunnar KahlmeterAbstract:ABSTRACT Fluoroquinolones (FQs) are among the drugs of choice for treatment of Salmonella infections. However, fluoroquinolone resistance is increasing in Salmonella due to chromosomal mutations in the quinolone resistance-determining regions (QRDRs) of the topoisomerase genes gyrA, gyrB, parC, and parE and/or plasmid-mediated quinolone resistance (PMQR) mechanisms including qnr variants, aac(6′)-Ib-cr, qepA, and oqxAB. Some of these mutations cause only subtle increases in the MIC, i.e., MICs ranging from 0.12 to 0.25 mg/liter for ciprofloxacin (just above the wild-type MIC of ≤0.06 mg/liter). These isolates are difficult to detect with standard ciprofloxacin Disk Diffusion, and plasmid-mediated resistance, such as qnr, is often not detected by the nalidixic acid screen test. We evaluated 16 quinolone/fluoroquinolone Disks for their ability to detect low-level-resistant Salmonella enterica isolates that are not serotype Typhi. A total of 153 Salmonella isolates characterized for the presence (n = 104) or absence (n = 49) of gyrA and/or parC topoisomerase mutations, qnrA, qnrB, qnrD, qnrS, aac(6′)-Ib-cr, or qepA genes were investigated. All isolates were MIC tested by broth microdilution against ciprofloxacin, levofloxacin, and ofloxacin and by Disk Diffusion using EUCAST or CLSI methodology. MIC determination correctly categorized all isolates as either wild-type isolates (MIC of ≤0.06 mg/liter and absence of resistance genes) or non-wild-type isolates (MIC of >0.06 mg/liter and presence of a resistance gene). Disk Diffusion using these antibiotics and nalidixic acid failed to detect some low-level-resistant isolates, whereas the 5-μg pefloxacin Disk correctly identified all resistant isolates. However, pefloxacin will not detect isolates having aac(6′)-Ib-cr as the only resistance determinant. The pefloxacin Disk assay was approved and implemented by EUCAST (in 2014) and CLSI (in 2015).
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performance of the eucast Disk Diffusion method the clsi agar screen method and the vitek 2 automated antimicrobial susceptibility testing system for detection of clinical isolates of enterococci with low and medium level vanb type vancomycin resistance a multicenter study
Journal of Clinical Microbiology, 2014Co-Authors: Gunnar Kahlmeter, Bjorg Haldorsen, Arnfinn Sundsfjord, Christian G Giske, Erika Matuschek, Kristin Hegstad, Kristian Schonning, Truls Michael LeegaardAbstract:Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n=28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n=12) and Enterococcus faecium (n=18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n=5), Norwegian (n=13), and Swedish (n=10) laboratories using the EUCAST Disk Diffusion method (n=28) and the CLSI agar screen (n=18) or the Vitek 2 system (bioMerieux) (n=5). The EUCAST Disk Diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P=0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST Disk Diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P<0.0001) or Merck Mueller-Hinton (MH) agar (P=0.027) for the Disk Diffusion assay performed significantly better than did laboratories using BBL MH II medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P=0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST Disk Diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, Disk Diffusion methodology requires that personnel be trained in interpreting zone edges.
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development of the eucast Disk Diffusion antimicrobial susceptibility testing method and its implementation in routine microbiology laboratories
Clinical Microbiology and Infection, 2014Co-Authors: Erika Matuschek, D F J Brown, Gunnar KahlmeterAbstract:Abstract With the support of ESCMID and European countries, EUCAST has developed a Disk Diffusion test with zone diameter breakpoints correlated with the EUCAST clinical MIC breakpoints. The development of the EUCAST Disk Diffusion method and quality control criteria are described, together with guidance on quality control and implementation of the method in clinical microbiology laboratories. The method includes the use of Mueller–Hinton agar without supplements for non-fastidious organisms and with 5% mechanically defibrinated horse blood and 20 mg/L β -NAD for fastidious organisms, a standardized inoculum resulting in confluent growth, an incubation time of 16–20 h, a reading guide on how to read zone diameters on individual species-agent combinations and zone diameter breakpoints calibrated to the EUCAST clinical MIC breakpoints. EUCAST recommendations are described in detail and updated regularly on the EUCAST website (http://www.eucast.org).
Yutsung Huang - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial susceptibilities of commonly encountered bacterial isolates to fosfomycin determined by agar dilution and Disk Diffusion methods
Antimicrobial Agents and Chemotherapy, 2011Co-Authors: Chiaying Liu, Yutsung Huang, Chunhsing Liao, Leejene Teng, Joh D Turnidge, Pore HsuehAbstract:We studied the antimicrobial activity of fosfomycin against 960 strains of commonly encountered bacteria associated with urinary tract infection using standard agar dilution and Disk Diffusion methods. Species studied included 3 common species of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia; methicillin-susceptible and -resistant Staphylococcus aureus; and vancomycin-susceptible and resistant Enterococcus faecalis and E. faecium. MICs and inhibition zone diameters were interpreted in accordance with both the currently recommended Clinical and Laboratory Standards Institute (CLSI) criteria for urinary tract isolates of Escherichia coli and Enterococcus faecalis and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria for Enterobacteriaceae. Tentative zone diameter interpretive criteria were developed for species not currently published by CLSI or EUCAST. Escherichia coli was uniformly susceptible to fosfomycin, as were most strains of Klebsiella pneumoniae and Enterobacter cloacae. A. baumannii was resistant to fosfomycin, while the prevalence of resistance in P. aeruginosa and S. maltophilia was greatly affected by the choice of MIC breakpoint. New tentative zone diameter criteria for K. pneumoniae, E. cloacae, S. aureus, and E. faecium were able to be set, providing some interim laboratory guidance for Disk Diffusion until further breakpoint evaluations are undertaken by CLSI and EUCAST.
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antimicrobial susceptibilities of commonly encountered bacterial isolates to fosfomycin determined by agar dilution and Disk Diffusion methods
Antimicrobial Agents and Chemotherapy, 2011Co-Authors: Chinglan Lu, John D Turnidge, Yutsung Huang, Chunhsing Liao, Leejene Teng, Po-ren HsuehAbstract:We studied the antimicrobial activity of fosfomycin against 960 strains of commonly encountered bacteria associated with urinary tract infection using standard agar dilution and Disk Diffusion methods. Species studied included 3 common species of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia; methicillin-susceptible and -resistant Staphylococcus aureus; and vancomycin-susceptible and resistant Enterococcus faecalis and E. faecium. MICs and inhibition zone diameters were interpreted in accordance with both the currently recommended Clinical and Laboratory Standards Institute (CLSI) criteria for urinary tract isolates of Escherichia coli and Enterococcus faecalis and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria for Enterobacteriaceae. Tentative zone diameter interpretive criteria were developed for species not currently published by CLSI or EUCAST. Escherichia coli was uniformly susceptible to fosfomycin, as were most strains of Klebsiella pneumoniae and Enterobacter cloacae. A. baumannii was resistant to fosfomycin, while the prevalence of resistance in P. aeruginosa and S. maltophilia was greatly affected by the choice of MIC breakpoint. New tentative zone diameter criteria for K. pneumoniae, E. cloacae, S. aureus, and E. faecium were able to be set, providing some interim laboratory guidance for Disk Diffusion until further breakpoint evaluations are undertaken by CLSI and EUCAST.