Ampicillin susceptibilities of vaginal and placental isolates of group B streptococcus and Escherichia coli obtained between 1992 and 1994

Abstract

Vaginal group B streptococcus (GBS) and Escherichia coli isolates were tested for their susceptibilities to ampicillin. All 414 GBS isolates tested were susceptible to ampicillin; the MIC at which 90% of the isolates were inhibited (MIC90) was 0.125 microg/ml, and the range was 0.06 to 0.25 microg/ml. The MIC50 for the 342 E. coli isolates tested was 4.0 microg/ml, and 27% were resistant to ampicillin.