Discrimination between epidemic and non-epidemic glycopeptide-resistant E. faecium in a post-outbreak situation

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Vancomycin-resistant enterococci (VRE) are increasingly isolated, with hospital-adapted strains exhibiting higher pathogenicity due to factors like enterococcal surface protein (Esp).
• Distinguishing between epidemic and non-epidemic VRE is crucial for effective infection control, as non-epidemic strains typically show lower pathogenicity.

Purpose of the Study:

• To investigate the molecular epidemiology of VRE during an outbreak in a German university hospital.
• To evaluate the utility of various typing methods, including esp PCR, for differentiating epidemic and non-epidemic VRE strains.

Main Methods:

• Pulsed-field gel electrophoresis (PFGE), esp PCR, multiple-locus variable number tandem repeat analysis (MLVA), purK1 typing, and multiple-locus sequence typing (MLST) were employed.
• Analysis of 28 representative VRE isolates from an outbreak period (2004-2005).

Main Results:

• Twenty-six non-epidemic and two epidemic VRE types were identified by PFGE.
• The majority of VRE isolates, including both epidemic and non-epidemic types, were positive for the esp gene.
• MLVA typing revealed significant diversity, with MLVA type 159 encompassing 16 PFGE types.

Conclusions:

• esp PCR shows promise for identifying non-epidemic VRE, despite a high prevalence of the esp gene in these strains.
• Current methods lack efficiency in distinguishing non-epidemic VRE, potentially leading to unnecessary patient isolation.
• Further development of rapid and accurate VRE typing methods is needed for effective outbreak management.