Effect of rifampin on ampicillin killing of group B streptococci.
The activity of rifampin against group B streptococci as a single agent and in combination with ampicillin was examined. The minimum concentration of rifampin required to inhibit 90% of the isolates of group B streptococci (18 of 20 isolates) was 0.6 microgram/ml. The checkerboard double-dilution studies of these two antibiotics and the time-killing studies both indicate that rifampin inhibits the bactericidal activity of ampicillin for group B streptococci.
D000667:Ampicillin / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D012293:Rifampin / Q000494:pharmacology*; D013292:Streptococcus agalactiae / Q000187:drug effects*; D013997:Time Factors
D000667:Ampicillin; D012293:Rifampin