Validity of screening procedures for glycopeptide-resistant enterococci

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Glycopeptide-resistant enterococci (GRE) pose a significant threat in healthcare settings.
• Accurate and efficient detection methods are essential for infection control.

Purpose of the Study:

• To evaluate the effectiveness of different screening agars and susceptibility testing methods for detecting GRE.
• To identify the most sensitive and specific methods for GRE identification.

Main Methods:

• Comparison of screening agars with varying vancomycin concentrations (4 µg/ml and 16 µg/ml).
• Evaluation of susceptibility testing methods: microbroth dilution (gold standard), disk diffusion, and E test.
• Species differentiation and polymerase chain reaction (PCR) for resistance gene detection.

Main Results:

• Screening agar with 16 µg/ml vancomycin showed high specificity (89.3%) and sensitivity (92.7%).
• Disk diffusion test achieved optimal sensitivity (98.8%) and specificity (99.6%) with a < 16 mm breakpoint.
• E test demonstrated 100% sensitivity and specificity but is less cost-effective for routine screening.

Conclusions:

• Combining inexpensive screening agar with disk diffusion or E test is a valid and cost-effective strategy for GRE detection.
• These methods facilitate timely identification and management of GRE infections.
• Optimized screening protocols are vital for controlling the spread of antimicrobial resistance.