Susceptibility of haemolytic oral enterococci to eight antibiotics in vitro

Abstract

In vitro tests by the agar dilution method for sensitivity to eight antibiotics were made with 92 strains of haemolytic enterococci isolated from oral infections. All strains were highly sensitive to azidocillin and ampicillin (minimum inhibitory concentration 0.5—2.0 mcg/ml). The antibacterial activity of benzylpenicillin was observed at 1.0—4.0 mcg/ml and that of phenoxymethylpenicillin between 2 and 8 mcg/ml. Most strains were sensitive to erythromycin (0.5—8.0 mcg/ml) while 70 per cent of the strains were sensitive to tetracycline (0.5—2.0 meg/ ml). The strains investigated were all resistant to cephalexine (64—128 mcg/ml) and the minimal inhibitory concentration of lincomycin varied between 16 and 128 mcg/ml.