Trends in antimicrobial resistance of clinical isolates of Enterococcus faecalis and Enterococcus faecium in Greece between 2002 and 2007.

We analysed trends in antimicrobial resistance of Enterococcus faecalis (N=1498) and E. faecium (N=625) recovered from clinical infections during 2002-2007 in a Greek tertiary care hospital. Molecular assays were used to confirm speciation and genotype of vancomycin-resistant enterococci (VRE). The incidence of infections per 1000 admissions caused by E. faecalis and E. faecium increased during the study period (chi(2) for trend=25.5 and 13.3, respectively; P<0.0001). Resistance to ampicillin, high level gentamicin and streptomycin, vancomycin, teicoplanin and linezolid was found in E. faecalis/E. faecium at rates of 1.3/82.4%, 45.6/51.2%, 48.9/69.1%, 0.5/9.6%, 0.1/8.2% and 0.3/1.6%, respectively. The vanA gene was identified in 79.1% of the VRE isolates, with vanB found in the remaining 20.1%. Analysis of antimicrobial resistance trends showed consistently high rates of ampicillin resistance among E. faecium isolates. For both enterococcal species, high level resistance to gentamicin and streptomycin were noted to have increased significantly (P<0.0001). Regardless of these alarming trends, strains exhibiting resistance to oxazolidinones seem to be only sporadic in our region and a trend toward increasing resistance rates to glycopeptides was not detected.