Effect of Selected Antibiotics and Other Inhibitors on Competence Development in Haemophilus influenzae

SUMMARY: The effect of streptomycin, penicillin, polymyxin, chloramphenicol, novobiocin, erythromycin, D-cycloserine, 8-azaguanine, and 6-azauracil on competence development in Haemophilus influenzae was studied.

D-cycloserine and 6-azauracil had no inhibitory effects on either competence development or cell viability in concentrations that were inhibitory to growth. Penicillin and polymyxin reduced cell viability and competence development proportionately thereby maintaining a high percentage of transformation in the treated cultures. Chloramphenicol, novobiocin, 8-azaguanine, erythromycin, and streptomycin inhibited markedly competence development with little or no effect on cell viability.