Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from two German hospitals.

Introduction

Vancomycin-resistant Enterococcus faecium accounts for around 10-23% of nosocomial enterococcal infections and constitutes a relevant therapeutic problem due to its limited susceptibility to antibiotics. The resistance towards glycopeptide antibiotics is mediated by the so-called van genes. Currently, the most common resistance type in Germany is the vanB-type. Little data are available on the molecular epidemiology in Germany. Therefore, an epidemiological typing of Enterococcus faecium isolates with vanB-type resistance from two German hospitals in Essen and Nuremberg was performed. Two outbreaks and 104 sporadic cases were investigated.

Methods

All 128 isolates with vanB-type resistance were collected between 2011-2012 and 2017-2018. They were characterized using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE).

Results

ST 117 was the most common sequence type (ST) in both hospitals, especially since 2017. PFGE divided the isolates of this study into 68 PFGE types and showed a broad genetic diversity. Two epidemiologically assumed in-hospital outbreaks were genetically confirmed. Apart from that, in-hospital transmissions were rare events.

Conclusion

The results obtained by MLST confirmed the previously described allocation of STs in Germany. PFGE showed a broad genetic diversity of vanB VRE between the two hospitals and also within each hospital. In-hospital transmissions were rare, but outbreaks did occur. Our data supports the strategy to screen and isolate patients in transmission events in order to detect monoclonality indicating a common source or hygiene mismanagement.