Convenient selective differential broth for isolation of vancomycin-resistant enterococcus from fecal material

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Vancomycin-resistant enterococcus (VRE) detection is crucial for infection control.
• Commercial vancomycin selective broths for VRE are not widely available.
• Direct plating methods may have limitations in VRE isolation sensitivity.

Purpose of the Study:

• To develop and evaluate an easily prepared vancomycin selective differential broth for VRE detection.
• To compare the efficacy of the developed broth enrichment method with direct plating on BEA agar for VRE isolation from fecal samples.

Main Methods:

• Developed a VRE selective differential broth (BEA VAN15 microg/ml).
• Compared broth enrichment followed by subculture to direct plating on BEA agar using 528 fecal samples.
• Evaluated bile esculin-positive colonies for VRE using standard microbiological techniques and molecular methods.

Main Results:

• The broth enrichment method detected significantly more VRE isolates (28) than direct plating (18).
• All 30 VRE isolates identified were Enterococcus faecium, with vancomycin MICs ranging from 32 to >256 microg/ml.
• The broth method reduced the number of non-VRE isolates requiring further workup, improving specificity.

Conclusions:

• An easily prepared vancomycin selective differential broth enhances VRE detection sensitivity and specificity compared to direct plating.
• This method offers a practical alternative for laboratories lacking commercial VRE selective broths.
• The developed broth aids in more efficient and accurate VRE screening from fecal specimens.