scholarly journals Combinations of Vancomycin and β-Lactams Are Synergistic against Staphylococci with Reduced Susceptibilities to Vancomycin

1999 ◽  
Vol 43 (7) ◽  
pp. 1747-1753 ◽  
Author(s):  
Michael W. Climo ◽  
Roberto L. Patron ◽  
Gordon L. Archer
Keyword(s):  
Single Agent ◽  
Rabbit Model ◽  
Test Methods ◽  
Disk Diffusion ◽  
Antistaphylococcal Activity ◽  
Vancomycin Mics ◽  
Disk Diffusion Testing ◽  
Antimicrobial Susceptibility Tests ◽  
Amoxicillin Clavulanate ◽  
Susceptibility Tests

ABSTRACT Evidence of synergism between combinations of vancomycin and β-lactam antibiotics against 59 isolates of methicillin-resistant staphylococci (Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus) for which vancomycin MICs ranged from 1 to 16 μg/ml were tested by broth microdilution checkerboard, disk diffusion, agar dilution, and time-kill antimicrobial susceptibility tests. The combination of vancomycin and oxacillin demonstrated synergy by all test methods against 30 of 59 isolates; no antagonism was seen. Synergy with vancomycin was also found by modified disk diffusion testing for ceftriaxone, ceftazidime, cefpodoxime, and amoxicillin-clavulanate but not for aztreonam. Evidence of synergy correlated directly with vancomycin MICs. The efficacy of vancomycin given alone and in combination with nafcillin was tested in the rabbit model of experimental endocarditis caused by three clinical isolates of glycopeptide-intermediate-susceptible S. aureus (GISA) (isolates HIP5827, HIP5836, and MU50). Two of the GISA isolates (isolates MU50 and HIP5836) were extremely virulent in this model, with 27 of 42 (64%) animals dying during the 3-day trial. Therapy with either vancomycin or nafcillin given as a single agent was ineffective for animals infected with HIP5827 or MU50. However, the combination of vancomycin and nafcillin resulted in a mean reduction of 4.52 log10 CFU/g of aortic valvular vegetations per g compared to the reduction for controls for animals infected with HIP5827 and a reduction of 4.15 log10 CFU/g for animals infected with MU50. Renal abscesses caused by HIP5827 were sterilized significantly better with the combination of vancomycin and nafcillin than by either treatment alone. We conclude that the combination of vancomycin and β-lactams with antistaphylococcal activity is an effective regimen for the treatment of infections with clinical strains of staphylococci which demonstrate reduced susceptibility to glycopeptides.

Comparison of the Vitek GPS-TB Card With Disk Diffusion Testing for Predicting the Susceptibility of Enterococci to Vancomycin

1999 ◽  
Vol 123 (7) ◽  
pp. 622-625
Author(s):  
Natalie Williams-Bouyer ◽  
Barbara S. Reisner ◽  
Carla E. Woodmansee ◽  
Pamela S. Falk ◽  
C. Glen Mayhall
Keyword(s):  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Test Methods ◽  
Disk Diffusion ◽  
National Committee ◽  
Repeat Testing ◽  
Disk Diffusion Testing ◽  
Intermediate Results

Abstract Objective.—To compare the ability of the Vitek GPS-TB card with disk diffusion testing for determining the susceptibility of enterococci to vancomycin. Design.—Vitek susceptibility testing was performed using the GPS-TB card and software version R05.03. Disk diffusion susceptibility testing was performed according to National Committee for Clinical Laboratory Standards guidelines. When discrepancies occurred between the interpretation of Vitek and disk diffusion, both tests were repeated and the epsilometer test (E test) and agar screen containing 6 μg/mL vancomycin were performed. Results.—Of 415 isolates tested, 313 were susceptible to vancomycin and 97 were resistant to vancomycin by both test methods. Two isolates were intermediate by Vitek and resistant by disk diffusion, 2 were intermediate by Vitek and susceptible by disk diffusion, and 1 was susceptible by Vitek and intermediate by disk diffusion. All but 1 of these latter 5 isolates (intermediate by Vitek and susceptible by disk diffusion) were available for retesting. On repeat testing, the 2 isolates that were intermediate by Vitek and resistant by disk diffusion were resistant by both methods, the 1 isolate that was intermediate by Vitek and susceptible by disk diffusion was susceptible by both methods, and the isolate that was susceptible by Vitek and intermediate by disk diffusion was also susceptible by both methods. These results were confirmed by E test and agar screen. Conclusion.—We found the results of the GPS-TB card compared well with disk diffusion. However, isolates with intermediate results by Vitek should be retested using another method, such as the E test.

scholarly journals Quality Control Guidelines for Disk Diffusion and Broth Microdilution Antimicrobial Susceptibility Tests with Seven Drugs for Veterinary Applications

2000 ◽  
Vol 38 (1) ◽  
pp. 453-455
Author(s):  
Brant A. Odland ◽  
Meredith E. Erwin ◽  
Ronald N. Jones
Keyword(s):  
Quality Control ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
E Coli ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

ABSTRACT 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.

scholarly journals Variety of β-Lactamases Produced by Amoxicillin-Clavulanate-Resistant Escherichia coli Isolated in the Northeastern United States

2004 ◽  
Vol 48 (5) ◽  
pp. 1520-1525 ◽  
Author(s):  
Keith S. Kaye ◽  
Howard S. Gold ◽  
Mitchell J. Schwaber ◽  
Lata Venkataraman ◽  
Youlin Qi ◽  
...  
Keyword(s):  
United States ◽  
Escherichia Coli ◽  
Tertiary Care ◽  
Disk Diffusion ◽  
Pcr Analysis ◽  
Care Hospital ◽  
E Coli ◽  
Disk Diffusion Testing ◽  
Amoxicillin Clavulanate ◽  
Agar Dilution

ABSTRACT This study analyzed the enzymatic basis and molecular epidemiology of amoxicillin-clavulanate-resistant Escherichia coli isolated by the microbiology laboratory of a United States tertiary care hospital. From October 1998 to December 1999, all E. coli isolates were screened for ampicillin-sulbactam resistance. Of 283 isolates that tested resistant to ampicillin-sulbactam, 69 unique patient isolates were also resistant to amoxicillin-clavulanate by disk diffusion testing (zone diameter ≤ 13 mm). These amoxicillin-clavulanate-resistant E. coli isolates underwent agar dilution testing, pulsed-field gel electrophoresis, PCR analysis, and isoelectric focusing. The mean age of study patients was 52 years; 78% were female. Among the isolates, 12 were nosocomial (rate of amoxicillin-clavulanate resistance = 4.7%) and 57 were community acquired (rate of amoxicillin-clavulanate resistance = 2.8%). No predominant strain was identified. By agar dilution testing, 67 isolates were nonsusceptible (39 resistant and 28 intermediate) to amoxicillin-clavulanate and 37 were piperacillin-tazobactam resistant but only 8 were ceftazidime resistant (ceftazidime MIC ≥ 32 μg/ml). Two isolates were susceptible to amoxicillin-clavulanic acid by agar dilution, although they were resistant by disk diffusion testing. The distribution of β-lactamases was as follows: the TEM type alone was found in 52 isolates, the AmpC type was found in 4 isolates (2 identified as containing CMY-2), the TEM type and CMY-2 were found in 2 isolates, and the OXA type was found in 1 isolate. Also, there was one isolate with the TEM type and the SHV type and one with the TEM type and a second, unidentified enzyme. Among the isolates with TEM-type enzymes, two extended-spectrum β-lactamase-producing isolates were identified but two isolates with inhibitor-resistant TEM (IRT) enzymes (one with TEM-34 [IRT-6] and the other with a novel enzyme [tentatively assigned the designation TEM-122]) were more interesting.

scholarly journals Beta-lactams susceptibility testing of penicillin-resistant, ampicillin-susceptible Enterococcus faecalis isolates: a comparative assessment of Etest and disk diffusion methods against broth dilution

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Natália Conceição ◽  
Wellington Francisco Rodrigues ◽  
Kessys Lorrânya Peralta de Oliveira ◽  
Lucas Emanuel Pinheiro da Silva ◽  
Laís Rezende Cardoso de Souza ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Reference Method ◽  
Poor Performance ◽  
Accurate Method ◽  
Disk Diffusion ◽  
Beta Lactam ◽  
Beta Lactams ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests ◽  
Broth Dilution

Abstract This study aimed to evaluate the accuracy of disk diffusion and Etest methods, compared to that of the broth dilution reference method for identifying beta-lactam susceptibilities of Penicillin-Resistant, Ampicillin-Susceptible Enterococcus faecalis (PRASEF) isolates. Fifty-nine PRASEF and 15 Penicillin-Susceptible, Ampicillin-Susceptible E. faecalis (PSASEF) clinical nonrepetitive isolates were evaluated. The effectiveness of five beta-lactams (ampicillin, amoxicillin, imipenem, penicillin, and piperacillin) was tested. All antimicrobial susceptibility tests were performed and interpreted according to the Clinical and Laboratory Standards Institute guidelines. Interpretative discrepancies, such as essential agreement, categorical agreement, and errors, were assessed. The acceptability was ≥ 90% for both categorical agreement and essential agreement. Etest proved to be an accurate method for testing beta-lactam susceptibilities of the emerging PRASEF isolates, disk diffusion presented poor performance, particularly for imipenem and piperacillin.

Performance Accuracy of Antibacterial and Antifungal Susceptibility Test Methods: Report From the College of American Pathologists Microbiology Surveys Program (2001–2003)

2006 ◽  
Vol 130 (6) ◽  
pp. 767-778 ◽  
Author(s):  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
Antifungal Susceptibility ◽  
Test Methods ◽  
Disk Diffusion ◽  
Test Accuracy ◽  
Broth Microdilution ◽  
Coagulase Negative Staphylococci ◽  
Disk Diffusion Test ◽  
Gram Negative ◽  
Antibacterial Test ◽  
Susceptibility Tests

Abstract Context.—The College of American Pathologists Microbiology Surveys Program provides external proficiency samples that monitor the performance of nearly 3000 laboratories that perform and report antimicrobial susceptibility tests. Objective.—To summarize results obtained with bacterial and yeast challenge samples (2001 through 2003). Design.—One organism every 4 months was tested by surveys participants against antibacterials/antifungals by routinely used methods. Reports were graded by interpretive category (susceptible, intermediate, resistant) based on an 80% consensus of referees/participants. Results.—The most common antibacterial test methods/ systems were Vitek (38%–43%), MicroScan (39%–43%), and the disk diffusion test (14%–15%), although Etest was most used for fastidious species. YeastOne was the dominant antifungal test (50%–55%). Antifungal results demonstrated continuous, improved accuracy (83%–88%), highest for YeastOne (96%) and broth microdilution (95%) methods. Antibacterial test accuracy was consistently greater than 97% against gram-positive organism challenges and greater than 98% against gram-negative challenges. For gram-negative strains with well-characterized resistance mechanisms, the accuracy by method was disk diffusion greater than broth microdilution greater than automated systems. Major problems identified were (1) Haemophilus influenzae control ranges require re-evaluation, (2) overuse of β-lactamase tests, (3) errors among Enterococcus faecium against penicillins (Vitek 2, MicroScan), (4) false-susceptible results with trimethoprim/sulfamethoxazole against coagulase-negative staphylococci (MicroScan), (5) macrolide false-susceptibility for β-hemolytic streptococcus (MicroScan), (6) flawed reporting for antimicrobials not active at the infection site, (7) use of outdated interpretive criteria, and (8) failure to follow Clinical and Laboratory Standards Institute testing/reporting recommendations. Conclusions.—Susceptibility tests were generally performing satisfactorily as measured by the surveys, but serious errors were identified with some drug/organism combinations that may require action by the Clinical and Laboratory Standards Institute and/or the Food and Drug Administration.

scholarly journals Molecular Epidemiology and Characterization of Carbapenem-Resistant Klebsiella pneumoniae Isolated from Urine at a Teaching Hospital in Taiwan

2021 ◽  
Vol 9 (2) ◽  
pp. 271
Author(s):  
Yuarn-Jang Lee ◽  
Chih-Hung Huang ◽  
Noor Andryan Ilsan ◽  
I-Hui Lee ◽  
Tzu-Wen Huang
Keyword(s):  
Klebsiella Pneumoniae ◽  
Teaching Hospital ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Pcr Analysis ◽  
Carbapenem Resistant ◽  
High Prevalence ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests ◽  
Tract Infections

Urinary tract infections (UTIs) are common in clinics and hospitals and are associated with a high economic burden. Enterobacterium Klebsiella pneumoniae is a prevalent agent causing UTIs. A high prevalence of carbapenem-resistant K. pneumoniae (CRKP) has emerged recently and is continuing to increase. Seventeen urinary CRKP isolates collected at a teaching hospital in Taiwan from December 2016 to September 2017 were analyzed to elucidate their drug resistance mechanisms. Two-thirds of the isolates were obtained from outpatients. Antimicrobial susceptibility tests demonstrated multidrug resistance in all the isolates. Multilocus sequence typing analysis showed high diversity among the isolates. PCR analysis demonstrated the presence of carbapenemases in three isolates. All isolates carried at least one other extended-spectrum β-lactamase, including TEM, DHA, and CTX-M. Fifteen isolates contained mutations in one of the outer membrane porins that were assessed. The expression levels of the acrB and/or oqxB efflux pump genes, as determined by qRT-PCR, were upregulated in 11 isolates. Six isolates might have utilized other efflux pumps or antimicrobial resistance mechanisms. These analyses demonstrated a highly diverse population and the presence of complex resistance mechanisms in urinary isolates of K. pneumoniae.

scholarly journals Presence of plasmid-mediated quinolone resistance (PMQR) genes in non-typhoidal Salmonella strains with reduced susceptibility to fluoroquinolones isolated from human salmonellosis in Gyeonggi-do, South Korea from 2016 to 2019

Gut Pathogens ◽  
2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Sohyun Lee ◽  
Nanjoo Park ◽  
Sujung Yun ◽  
Eunseon Hur ◽  
Jiwon Song ◽  
...  
Keyword(s):  
South Korea ◽  
Pcr Amplification ◽  
Public Health Problem ◽  
Test Method ◽  
Quinolone Resistance ◽  
Human Salmonellosis ◽  
Pcr Products ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests ◽  
Sequence Types

AbstractNon-typhoidal salmonellosis remains a pressing public health problem worldwide. Quinolones, particularly fluoroquinolones, are widely used to treat various infections, including non-typhoidal salmonellosis, which can be a serious illness. The emergence of fluoroquinolone-resistant Salmonella has resulted in treatment failure and high mortality rates. In this study, we estimated the presence of plasmid-mediated quinolone resistance (PMQR) genes in Salmonella enterica isolated from human salmonellosis patients in South Korea from 2016 to 2019. We evaluated the association of these genes with fluoroquinolone susceptibility. Antimicrobial susceptibility tests for Salmonella isolates were performed using the Vitek II system, and the minimum inhibitory concentrations (MIC) of ciprofloxacin and levofloxacin were determined using the E-test method. Plasmid-mediated quinolone resistance (PMQR) genes were detected by PCR amplification and quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were analyzed following Sanger sequencing of the PCR products. Thirty-four Salmonella strains with reduced susceptibility to fluoroquinolones (ciprofloxacin MIC ≥ 0.125 µg/mL and levofloxacin MIC ≥ 0.25 µg/mL) were selected from 208 human clinical Salmonella isolates. Among them, 22 Salmonella strains harbored one PMQR gene (qnrA, qnrB, or qnrS), and three Salmonella strains carried two PMQR genes (qnrS and aac(6′)-Ib-cr or qnrA and qnrB). qnrS was the most common PMQR gene. Serotyping revealed that Salmonella 4,[5]12:i:- (32.4%, 11/34) and Salmonella Typhimurium (29.4%, 10/34) were the two most predominant serovars, and Multi-locus sequence typing (MLST) showed that ST19 and ST34 were the most frequent sequence types. In conclusion, qnr gene-positive Salmonella 4,[5],12:i:- and Salmonella Typhimurium were the main serovars responsible for reduced susceptibility to fluoroquinolones. Therefore, our findings suggest that PMQR-positive Salmonella strains, which can be isolated from various samples including human, food, and the environment, should be carefully monitored.

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