Prevalence of Antimicrobial Resistance in Enterococcus Isolates in Australia, 2005: Report from the Australian Group on Antimicrobial Resistance

Antibiotic resistance in Enterococcus species causing clinical disease was examined in a point-prevalence study in 2005. Twenty-two sites around Australia collected up to 100 consecutive isolates and tested them for susceptibility to ampicillin, vancomycin, high-level gentamicin and/or high-level streptomycin using standardised methods. Results were compared to similar surveys conducted in 1995, 1999 and 2003. In the 2005 survey, Enterococcus faecalis (1,987 strains) and E. faecium (180 strains) made up 98.6% of the 2,197 isolates tested. Ampicillin resistance was common (77%) in E. faecium, but rare still in E. faecalis (0.2%). Resistance to vancomycin was 7.2% in E. faecium and 0.2% in E. faecalis; the vanB gene was detected in all vancomycin-resistant isolates. High-level resistance to gentamicin was 35.8% in E. faecalis and 52.2% in E. faecium; the figures for high-level streptomycin resistance were 10.3% and 60.2% respectively. Compared to previous Australian Group on Antimicrobial Resistance surveys in 1995, 1999 and 2003, the proportions of vancomycin resistance and high-level gentamicin resistance in enterococci are increasing. It is important to have an understanding of the occurrence of vancomycin resistant enterococci and high level aminoglycoside resistance in Australia to guide infection control practices, antibiotic prescribing policies and drug regulatory decisions.