Genetic typing of Enterococcus faecium VRE strains isolated in three hospitals in Warsaw and Siedlce in 2015-2016

INTRODUCTION: Since the first report of vancomycin-resistant enterococci (VRE) in Poland, in 1996, these strains have spread in Polish hospitals, mainly due to selective pressure associated with increased use of vancomycin in the treatment of infections caused by methicillin-resistant staphylococci and Clostridium difficile. At the beginning of 2016 a growing number of patients colonized with VRE in the gastrointestinal tract was observed in the Children’s Memorial Health Institute (IPCZD). Some of these patients were transferred from other hospitals, and VRE colonization was found on admission. AIM: To analyze genetic similarity of VRE strains isolated from patients hospitalized in IPCZD and two other hospitals in Mazovian district, genetic typing by pulsed field gel electrophoresis (PFGE) was performed. MATERIALS AND METHODS: VRE strains were isolated from rectal swabs, and other clinical samples such as blood, cerebrospinal fluid, other body fluids, and environmental samples. A total of 56 VRE strains from IPCZD, 20 strains from Siedlce and 4 strains from patients from Grochowski Hospital in Warsaw were typed by PFGE. RESULTS: PFGE typing revealed 4 VRE clones containing several strains with identical restriction patterns. Among VRE strains isolated from neonates hospitalized in IPCZD, two clones with 24 and 20 identical strains were found. Respectively, 16 (67%) and 12 (60%) isolates were originated from rectal swabs from patients at admission to the hospital. Clonal strains were identified in all three hospitals included in the study. CONCLUSIONS: Our results showed that VRE strains had spread in the region. Isolation of clonal strains on admission to the hospital suggested independent VRE introductions from environment or other hospitals. Identification of clonal strains obtained from rectal swabs and other clinical samples during hospitalization indicated horizontal transmission.