Susceptibility of group B streptococcus to beta-lactam antibiotics

S. A. McGeary, K. S. Kim, J. I. Ward

Research output: Contribution to journalArticlepeer-review


To evaluate the relative activity of fourteen beta-lactam agents, including seven new agents, the susceptibility of 77 clinical isolates of group B streptococci were measured using an agar dilution technique. Thienamycin, cefotaxime and azlocillin had better activity than penicillin, with MIC50 of ≤ 0.015 μg/ml. Ampicillin, cefamandole, cefazolin, cefoperazone, mezlocillin and piperacillin had activity similar to penicillin with MIC50 of 0.03-0.06 μg/ml. Oxacillin, ticarcillin, cefoxitin and moxalactam were less active than penicillin with MIC50 of 0.25-2 μg/ml. Susceptibility to five of the more active antibiotics was markedly reduced, however, when the inoculum size was increased from 104 to 108 colony forming units/ml.

Original languageEnglish (US)
Pages (from-to)693-696
Number of pages4
JournalDrugs under Experimental and Clinical Research
Issue number10
StatePublished - Jan 1 1983
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology
  • Drug Discovery
  • Pharmacology (medical)


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