Results of Disk Diffusion Testing with Cefoxitin Correlate with Presence of mecA in Staphylococcus spp.

ABSTRACT The in vitro activities of fluconazole and voriconazole against 1,024 clinical isolates of Candida spp. were determined by the agar disk diffusion test using the Clinical and Laboratory Standards Institute (CLSI) M44-A guidelines. The results of this investigation demonstrated the broad-spectrum in vitro activity of voriconazole, relative to that of fluconazole, against yeasts tested, in particular fluconazole-resistant isolates, such as Candida krusei that showed high susceptibility to voriconazole. The situation in Turin, Italy, is quite similar to that of the rest of Italy, reflecting the worldwide trend.

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Minimum Inhibitory Concentration Breakpoints and Disk Diffusion Inhibitory Zone Interpretive Criteria for Tilmicosin Susceptibility Testing against Pasteurella Spp. Associated with Bovine Respiratory Disease

Journal of Veterinary Diagnostic Investigation ◽

10.1177/104063879600800310 ◽

1996 ◽

Vol 8 (3) ◽

pp. 337-344 ◽

Cited By ~ 14

Author(s):

Thomas R. Shryock ◽

Donald W. White ◽

J. Mitchell Staples ◽

Carolyn S. Werner

Keyword(s):

Respiratory Disease ◽

Susceptibility Testing ◽

Clinical Laboratory ◽

Bovine Respiratory Disease ◽

Disk Diffusion ◽

National Committee ◽

Pharmacokinetic Data ◽

In Vitro Test ◽

Disk Diffusion Testing

Tilmicosin is a novel macrolide antibiotic developed for exclusive use in veterinary medicine. The first tilmicosin-containing product was approved to treat bovine respiratory disease associated with pasteurellae. The development of antimicrobial susceptibility testing guidelines for tilmicosin was predicated on the relationship of clinical efficacy studies that demonstrated a favorable therapeutic outcome, on pharmacokinetic data, and on in vitro test data, as recommended by the National Committee for Clinical Laboratory Standards (NCCLS). The NCCLS-approved breakpoints for the MIC dilution testing are resistant ‡ 32 g/ml, intermediate 16 g/ml, and susceptible £ 8 g/ml. The zone of inhibition interpretive criteria for disk diffusion testing with a 15- g disk are resistant £ 10 mm, intermediate 11–13 mm, and susceptible ‡ 14 mm.

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Comparison of results of fluconazole and voriconazole disk diffusion testing for Candida spp. with results from a central reference laboratory in the ARTEMIS DISK Global Antifungal Surveillance Program

Diagnostic Microbiology and Infectious Disease ◽

10.1016/j.diagmicrobio.2009.05.007 ◽

2009 ◽

Vol 65 (1) ◽

pp. 27-34 ◽

Cited By ~ 16

Author(s):

Michael A. Pfaller ◽

Linda Boyken ◽

Richard J. Hollis ◽

Jennifer Kroeger ◽

Shawn A. Messer ◽

...

Keyword(s):

Disk Diffusion ◽

Surveillance Program ◽

Reference Laboratory ◽

Candida Spp ◽

Comparison Of Results ◽

Disk Diffusion Testing

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Predictive value of direct disk diffusion testing from positive blood cultures in a children’s hospital and its utility in antimicrobial stewardship

Journal of Clinical Microbiology ◽

10.1128/jcm.02445-20 ◽

2021 ◽

Author(s):

Timothy J. Savage ◽

Shun Rao ◽

Jill Joerger ◽

Al Ozonoff ◽

Alexander J. McAdam ◽

...

Keyword(s):

Predictive Value ◽

Retrospective Cohort ◽

Pediatric Patients ◽

Susceptibility Testing ◽

Blood Cultures ◽

Disk Diffusion ◽

Antibiotic Prescribing ◽

Gram Stain ◽

Disk Diffusion Testing ◽

Sensitivity Specificity

Background Accurate and early susceptibility results could reduce overuse of broad-spectrum antibiotics for empiric treatment of bacteremia. Direct disk diffusion testing (dDD) using non-standardized inocula directly from blood cultures could facilitate earlier narrowing of antibiotics. Methods To determine the predictive value of dDD compared with standardized antimicrobial susceptibility testing (AST), we performed a retrospective cohort study of 582 blood cultures from 495 pediatric patients with bacteremia. Positive and negative predictive value (PPV: number of isolates susceptible by both dDD and AST divided by the total number of isolates susceptible by dDD; NPV: number of isolates not susceptible [either intermediate or resistant] by both dDD and AST divided by the total number of isolates not susceptible by dDD), sensitivity, specificity, and 95% confidence interval were calculated for each bacterium-antibiotic combination. We evaluated the Antibiotic Spectrum Index of prescribed antibiotics to assess change in antibiotic prescribing after availability of Gram stain, dDD, and AST results. Results dDD results were available a median of 21 hours before AST results. dDD had PPVs of ≥96% for most organism-antibiotic pairs, including 100% (CI 96-100%) for Staphylococcus aureus and oxacillin and 99% (CI 93%-100%) for Enterobacterales and ceftriaxone. NPVs of dDD were variable and frequently lower than PPV. Very major errors and major errors occurred in 31/5454 (0.6%) and 231/5454 (4.2%) organism-antibiotic combinations, respectively. Antibiotics were narrowed in 30% of cases after dDD result and a further 25% of cases after AST result. Conclusions dDD is highly predictive of susceptibility for many common organism-antibiotic combinations and provides actionable information one day earlier than standard susceptibility approaches. dDD has the potential to facilitate earlier de-escalation to narrow-spectrum antibiotic treatment.

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Methods for Improved Detection of Oxacillin Resistance in Coagulase-Negative Staphylococci: Results of a Multicenter Study

Journal of Clinical Microbiology ◽

10.1128/jcm.37.12.4051-4058.1999 ◽

1999 ◽

Vol 37 (12) ◽

pp. 4051-4058 ◽

Cited By ~ 41

Author(s):

Fred C. Tenover ◽

Ronald N. Jones ◽

Jana M. Swenson ◽

Barbara Zimmer ◽

Sigrid McAllister ◽

...

Keyword(s):

Clinical Laboratory ◽

Reference Method ◽

Disk Diffusion ◽

National Committee ◽

Broth Microdilution ◽

Pcr Assay ◽

Coagulase Negative Staphylococci ◽

Oxacillin Resistance ◽

Disk Diffusion Testing ◽

Single Disk

A multilaboratory study was undertaken to determine the accuracy of the current National Committee for Clinical Laboratory Standards (NCCLS) oxacillin breakpoints for broth microdilution and disk diffusion testing of coagulase-negative staphylococci (CoNS) by using a PCR assay for mecA as the reference method. Fifty well-characterized strains of CoNS were tested for oxacillin susceptibility by the NCCLS broth microdilution and disk diffusion procedures in 11 laboratories. In addition, organisms were inoculated onto a pair of commercially prepared oxacillin agar screen plates containing 6 μg of oxacillin per ml and 4% NaCl. The results of this study and of several other published reports suggest that, in order to reliably detect the presence of resistance mediated bymecA, the oxacillin MIC breakpoint for defining resistance in CoNS should be lowered from ≥4 to ≥0.5 μg/ml and the breakpoint for susceptibility should be lowered from ≤2 to ≤0.25 μg/ml. In addition, a single disk diffusion breakpoint of ≤17 mm for resistance and ≥18 mm for susceptibility is suggested. Due to the poor sensitivity of the oxacillin agar screen plate for predicting resistance in this study, this test can no longer be recommended for use with CoNS. The proposed interpretive criteria for testing CoNS have been adopted by the NCCLS.

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