High Level Aminoglycoside Resistance in Enterococcal Blood Culture Isolates

Enterococci may display high level resistance to aminoglycosides, in which case synergy with cell-wall active antibiotics will be lost. All enterococcal blood culture isolates at Royal Brisbane Hospital have been screened by agar dilution for high level resistance to gentamicin and streptomycin since 1989. Of 110 isolates of Enterococcus faecalis, 16% displayed high level resistance to gentamicin and 10% showed high level resistance to streptomycin. Four isolates had high level resistance to both antibiotics. None of 23 Enterococcus faecium isolates displayed high level resistance to gentamicin and only one to streptomycin. Two Enterococcus faecium isolates were resistant to amoxycillin but none to vancomycin. There has been no apparent increase in high level aminoglycoside resistance from 1989 to 1996. High level gentamicin resistant isolates were relatively more common in liver transplant patients. Like vancomycin-resistant enterococci, isolates that are high level resistant to aminoglycosides can be spread by the hands of staff members. Preventing the nosocomial transmission of high level aminoglycoside-resistant enterococci follows the same general principles of preventing transmission of other resistant enterococci. Comm Dis Intell 1996;20:532-535.