Vancomycin-Resistant Enterococcus (VRE)-Introduction, Detection Methods, and Keynotes
Introduction of Vancomycin-Resistant Enterococcus (VRE)
Vancomycin-Resistant Enterococcus (VRE) refers to strains of Enterococcus (primarily E. faecium and occasionally E. faecalis) that have acquired resistance to vancomycin, an important glycopeptide antibiotic used for gram-positive infections.
VREs are major nosocomial pathogens, particularly in ICUs, transplant units, and oncology wards.
Resistance is usually due to the acquisition of van genes (vanA, vanB, etc.) that alter cell wall precursors from D-Ala-D-Ala to D-Ala-D-Lac, reducing vancomycin binding.
Detection Methods for Vancomycin-Resistant Enterococcus (VRE)
Not reliable for vancomycin due to poor correlation with MIC
| Method | Details |
|---|---|
| Disk Diffusion (not preferred) | |
| Broth Microdilution / E-test | Gold standard for MIC determination (e.g., MIC ≥32 µg/mL = VRE) |
| Chromogenic VRE Agar | Selective media showing characteristic colored colonies |
| VITEK 2 / Phoenix / MicroScan | Automated identification & susceptibility systems |
| PCR for van genes (vanA, vanB) | Molecular confirmation of resistance genes |
| Latex agglutination (rare) | Detection of VanA/VanB antigens (less commonly used) |
Keynotes on Vancomycin-Resistant Enterococcus (VRE)
- VRE primarily involves E. faecium, which is more prone to multidrug resistance than E. faecalis.
- vanA gene confers high-level resistance to both vancomycin and teicoplanin.
- vanB gene confers variable vancomycin resistance, but teicoplanin susceptibility is retained.
- Colonization (especially rectal) often precedes infection; routine screening may be required in outbreak settings.
- Common infections include UTIs, bloodstream infections, endocarditis, and wound infections.
- VRE spreads via the hands of healthcare workers and contaminated hospital surfaces.
- Treatment options include linezolid, daptomycin, tigecycline, and newer agents like oritavancin.
- Contact precautions and infection control are crucial in preventing nosocomial outbreaks.
- Surveillance cultures and antimicrobial stewardship play a role in controlling the spread of VRE.
- VRE is resistant to many antibiotics, including β-lactams and aminoglycosides (in some strains).
Further Readings
- https://www.ncbi.nlm.nih.gov/books/NBK513233/
- https://www.cdc.gov/vre/about/index.html
- https://www.webmd.com/skin-problems-and-treatments/what-is-vre
- https://www.nth.nhs.uk/resources/vancomycin-resistant-enterococci-vre/
- https://medlineplus.gov/ency/patientinstructions/000476.htm
- https://www.health.ny.gov/diseases/communicable/vancomycin_resistant_enterococcus/fact_sheet.htm
- https://www.healthline.com/health/vre
- https://www.kch.nhs.uk/wp-content/uploads/2023/01/pl-300.4-vancomycin-resistant-enterococci-vre.pdf
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