Outbreak of multidrug-resistant Enterococcus faecium with transferable vanB class vancomycin resistance

Area of Science:

• Microbiology
• Infectious Diseases
• Hospital Epidemiology

Background:

• Nosocomial infections caused by multidrug-resistant Enterococcus faecium are a growing concern.
• The emergence of vancomycin resistance, particularly vanB class, poses significant treatment challenges.

Purpose of the Study:

• To investigate an outbreak of vancomycin-resistant Enterococcus faecium (VRE) at a university-affiliated hospital.
• To identify risk factors for acquisition and effective control measures for the epidemic strain.

Main Methods:

• Molecular typing (restriction endonuclease analysis) to assess clonality of isolates.
• Antimicrobial susceptibility testing, including vancomycin Minimum Inhibitory Concentrations (MICs).
• Plasmid and chromosomal DNA analysis to evaluate vancomycin resistance transferability.

Main Results:

• Thirty-seven patients were infected with a single clone of ampicillin-, gentamicin-, and vancomycin-resistant Enterococcus faecium (vanB type).
• Vancomycin resistance was transferable, with MICs ranging from 8 to 256 µg/ml.
• Proximity to other patients and exposure to healthcare workers caring for cases were significant risk factors.
• Environmental contamination was higher when patients had diarrhea.
• Isolation in private rooms and use of gowns and gloves controlled the outbreak.

Conclusions:

• Multidrug-resistant Enterococcus faecium with transferable vanB resistance is an emerging nosocomial pathogen.
• Diarrhea in infected patients significantly increases environmental contamination risk.
• Strict barrier precautions, including gowns and gloves, are crucial for controlling outbreaks of this VRE strain.