Antibiotic resistance in enterococci at a teaching hospital

Antibiotic resistance in enterococci is becoming increasingly common throughout the world. Of particular therapeutic concern are strains which produce beta-lactamase, display high-level aminoglycoside resistance or show plasmid-mediated resistance to vancomycin. A prospective survey of 112 enterococcal isolates has been carried out to determine the extent of these resistance mechanisms in a Sydney teaching hospital. No beta-lactamase production was found. Eleven (9.8%) strains displayed high-level streptomycin resistance (MIC greater than 2048 mg/l), and 2 (1.8%) strains high-level gentamicin resistance (MIC greater than 2048 mg/l). No vancomycin resistance was observed. Enterococcal resistance is not as common at this hospital as in many centres in other countries. High-level aminoglycoside resistance may be missed on routine sensitivity testing. All enterococcal isolates from patients with serious infections should be screened for high-level aminoglycoside resistance.