Assessment of high-level gentamicin and glycopeptide-resistant Enterococcus faecalis and E. faecium clonal structure in a Portuguese hospital over a 3-year period.

This study focussed on the clonal structure and temporal distribution of E. faecalis and E. faecium with high-level resistance to gentamicin (HLGR) and glycopeptides (GR) collected from clinical samples during 2004 to 2006 at a Portuguese Hospital. The findings were an E. faecalis-dominant and epidemic clone (PFGE-AO), the maintenance of a major epidemic E. faecium clone (PFGE-c) and a high prevalence of putative virulence genes--asa1 (aggregation substances), gelE (gelatinase), cylA (cytolysin), esp (enterococcal surface protein), and hyl (hyaluronidase)--most of them significantly associated with the major clones of both species. The E. faecalis GR isolates ST6 and the E. faecium GR isolates ST17, ST18 and ST280 belong to the clonal complexes E. faecalis-CC2 and E. faecium-CC17, which are well adapted to the nosocomial setting and are disseminated worldwide. This study highlights the need for continuous and active surveillance in this Portuguese hospital in order to follow the evolution of these epidemic and persistent clones.