Antibiotic-killing kinetics of group B streptococci.

Group B streptococci are uniformly susceptible to penicillin or ampicillin. Nevertheless, morbidity and mortality in newborn infants infected with group B streptococci is a major clinical problem. Bacteriologic determinants in the outcome of this infection were studied. Streptococcal killing kinetics were studied for ampicillin alone and in combination with gentamicin. In all cases killing was accelerated by the combination. The practice of discontinuing administration of the aminoglycoside antibiotic when group B streptococcal infection is confirmed should be re-evaluated.