Determination of high level resistance to aminoglycosides among enterococci.

Two hundred and ten strains of enterococci showing resistance to gentamicin (10 micrograms/disc) were tested for high level resistance by detecting the minimum inhibitory concentration and by using high content disc diffusion test. Only 67 per cent of these had high level resistance to gentamicin. High level kanamycin resistance in the group was 84 per cent, while high level streptomycin resistance was 61 per cent. Only 85 of the 140 strains with high level gentamicin resistance had similar streptomycin resistance. Results using locally made high content discs, correlated 100 per cent with MIC results. High level resistance to enterococci should be reported on a routine basis, especially when isolated from patients with serious infections.