Clinical isolates of enterococci with high-level resistance to currently available aminoglycosides

Enterococci isolated from different body sites were tested for high-level gentamicin resistance. A total of 139 enterococcal isolates were screened for resistance (minimum inhibitory concentration [MIC] greater than 2000 mg l-1) by a broth-tube method. Twenty-five (18%) were found to exhibit resistance and this was confirmed by agar screening (1000 mg l-1) and agar dilution MIC determinations. The majority of isolates also showed high-level resistance to kanamycin and streptomycin. The remaining isolates showed high-level resistance to gentamicin and kanamycin but not streptomycin. A retrospective clinical review was performed. Most patients had a source of definite or likely infection (78%). Serious infections such as endocarditis or meningitis were not observed during the course of this study. Retrospective clinical data suggest that in cases not involving endocarditis or meningitis, neither infection refractory to therapy nor relapse of infection is a common sequel to infection with gentamicin-resistant enterococci in hospitalized patients.