Changes in vancomycin-resistant Enterococcus faecium causing outbreaks in Brazil

SummaryEnterococci have been implicated in severe human infections as a consequence of associated determinants of virulence and antimicrobial resistance. The majority of vancomycin-resistant Enterococcus faecium (VREfm) connected to outbreaks worldwide pertains to the clonal complex 17 (CC17). In Brazil, the majority of VREfm involved in outbreaks reported so far are not related to CC17. VREfm strains responsible for an outbreak and sporadic cases in hospitals located in the city of Campinas, Brazil, were compared to other VREfm strains in the country. Twenty-two out of 23 E. faecium were vancomycin-resistant and harboured the vanA gene. One vancomycin-susceptible E. faecium (VSEfm) strain was included in this study because it was isolated from a patient who one week later harboured a VREfm. All strains, except VSE, showed the same alteration in the VanA element characterised by deletion of the left extremity of the transposon and insertion of IS1251 between the vanS and vanH genes. Genes codifying virulence factors such as collagen–adhesin protein, enterococcal surface protein and hyaluronidase were detected in the VREfm and VSEfm studied. Both pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) revealed that VREfm and VSEfm strains have a clonal relationship. New sequence types (STs) were identified by MLST as ST447, ST448, ST478 and ST412 but all belonged to the CC17. The present study revealed that VREfm outbreaks in Brazil were caused by strains that did not share a common evolutionary history, and that VREfm strains belonging to CC17 could be predominant in Brazil as in other countries.