Epidemiology of vancomycin-resistant Enterococcus faecium in Greek hospitals by PFGE and MLST

Abstract number: P2121

Karanika M., Klapsa D., Neokleous C., Spiliopoulou I., Koutsia-Carouzou C., Economou M., Karaiskos K., Kouraki K., Krikou D., Anifantaki M., Vlahaki E., Petinaki E.

Objectives:Enterococcus spp. is an important cause of nosocomial infections worldwide. Nowadays, the dissemination of vancomycin-resistant enterococci (VRE), remains a major problem in hospital environments. The aim of this study was to investigate the epidemiological relatedness of vancomycin-resistant Enterococcus faecium isolated from clinically significant specimens in different Greek hospitals.

Materials and Methods: A total of 100 vancomycin-resistant Enterococcus faecium (VRE), isolated from hospitalised patients throughout Greece were included. These isolates were recovered from urine, stool, blood and pus. Identification to the species level was done by PCR based on sodA gene, while vancomycin-resistance was associated with vanA gene. The clonality of isolates was tested by PFGE, after digestion of DNA with SmaI. To increase the sensitivity of our approach, due to the difficulty of determining small differences in band patterns by PFGE, strains of similar cloning patterns were also subjected to Multi Locus Sequence Typing (MLST) and the results compared. Detection of pathogenic genes esp, gel, as, ace and efa genes was performed by PCR, using specific primers.

Results: From the 100 VRE isolates, twenty-two different PFGE clones were noticed. Throughout each hospital, similar clones were observed. Between strains with similar PFGE pattern, differences were observed after MLST typing. The majority of isolates carried the esp gene, and they were negative for all the remaining genes.

Conclusions: PFGE remains a technique that is usefully applied for the primary surveillance of epidemic clones in hospitals, while MLST is an extremely important tool and should be used in conjunction with PFGE.