Sensitivity of 941 beta haemolytic streptococci to antibacterial drugs

Nine hundred and forty-one strains of beta haemolytic streptococci were Lancefield grouped and their antibiotic sensitivities tested by the agar plate diluting technique to penicillin, erythromycin, lincomycin, tetracycline and sulphafurazole. All the strains tested were sensitive to two units per ml or less of penicillin. This MIC is higher than that reported in other surveys and indicates increasing resistance of these organisms to penicillin. All the strains tested were sensitive to two mug/ml or less of erythromycin. Fifty percent of all strains were resistant to tetracycline and sulphafurazole.