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Detection of vancomycin resistance in Enterococcus species
B M Willey1, B N Kreiswirth, A E Simor
1Department of Microbiology, Mount Sinai Hospital, University of Toronto, Ontario, Canada.
Journal of Clinical Microbiology
|July 1, 1992
Summary
Vancomycin resistance in Enterococcus faecalis and Enterococcus faecium is a growing concern. A new agar screen plate method demonstrated 100% sensitivity and specificity for detecting this resistance.
Area of Science:
- Clinical Microbiology
- Antimicrobial Resistance
- Infectious Diseases
Background:
- Vancomycin-resistant Enterococcus (VRE) isolates, specifically Enterococcus faecalis and Enterococcus faecium, have emerged in North America and Europe.
- Susceptibility testing is crucial for managing VRE infections.
Purpose of the Study:
- To evaluate the performance of different methods for detecting vancomycin resistance in enterococci.
- To assess the accuracy of automated systems and a novel agar screen plate method.
Main Methods:
- Broth microdilution and disk diffusion methods were used following National Committee for Clinical Laboratory Standards (NCCLS) guidelines.
- Automated systems (Vitek GPS-TA and MicroScan Walk/Away) were evaluated.
- A novel agar screen plate method was tested at various vancomycin concentrations.
Main Results:
- Broth microdilution identified 98 resistant, 52 moderately susceptible, and 5 intermediate enterococcal isolates.
- The MicroScan panel showed higher sensitivity (93-99%) compared to the Vitek card (72%).
- The agar screen plate method achieved 100% sensitivity and specificity for vancomycin resistance detection.
Conclusions:
- The agar screen plate method is a highly sensitive and specific tool for detecting vancomycin resistance in enterococci.
- Manual reading of the MicroScan panel enhances its sensitivity for VRE detection.
- Accurate and efficient detection methods are vital for controlling the spread of VRE.