Experimental group B streptococcal endocarditis treated with penicillin G versus ceftizoxime

Arnold S. Bayer, Joan O. Morrison, Kwang Sik Kim

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Aortic valve endocarditis due to a penicillin G (PNC) and ceftizoxime (CZ)-sensitive group B streptococcus (GBS) was induced in 72 rabbits. Animals received either procaine PNC (300 mg/kg per day) or CZ (150 mg/kg/day) for 3, 6, or 9 days. PNC rapidly sterilized blood cultures (≤3 days) and significantly reduced vegetation GBS titers versus controls at all three sacrifice times (p < 0.0005). In contrast, CZ exerted a slow in vivo bactericidal effect with vegetation titers not significantly different from controls until day 9 of therapy. By day 9 of therapy, 65/89 (73%) of vegetations were sterilized by PNC versus only 24/94 (26%) sterilized by CZ (p < 0.0005). This marked in vitro-in vivo disparity in CZ-treated animals occurred despite 100% of individual serum bactericidal titers ≥ 1:32 and 100% of individual CZ serum levels ≥ 100 times the GBS MBC. The suboptimal CZ in vivo effect was not related to: (1) development of CZ resistance on therapy; (2) CZ inactivation, or (3) inoculum-growth phase effect.

Original languageEnglish (US)
Pages (from-to)352-361
Number of pages10
Issue number5
StatePublished - Jan 1 1983
Externally publishedYes


  • Group B streptococci
  • Infective endocarditis
  • Third-generation cephalosporins

ASJC Scopus subject areas

  • Oncology
  • Pharmacology
  • Drug Discovery
  • Pharmacology (medical)
  • Infectious Diseases


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