In vitro susceptibility of 104 clinical isolates of Haemophilus influenzae to moxalactam (LY127935), ampicillin, chloramphenicol, and ticarcillin

Edward Mason, Sheldon Kaplan, D. C. Anderson, D. B. Hinds, R. D. Feigin

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

A total of 104 strains of Haemophilus influenzae isolated from pediatric patients over a 1-year period were tested for susceptibility to moxalactam (LY127935), ampicillin, chloramphenicol, and ticarcillin. Of these strains, 30 produced β-lactamase. LY127935 inhibited 99% of the strains at a concentration of 0.125 μg/ml; the remaining strain was inhibited by this antibiotic at 0.25 μg/ml. β-Lactamase-producing strains were inhibited by ampicillin at ≥ 2 μg/ml. β-Lactamase-negative strains were all inhibited by ampicillin at ≤ 1 μg/ml, except for one nontypable strain which required 2 μg of ampicillin per ml for inhibition. All strains were susceptible to chloramphenicol at ≤ 4 μg/ml. β-Lactamase-producing strains were less susceptible (geometric mean = 4.702 μg/ml) to ticarcillin than were strains which did not produce β-lactamase (geometric mean = 0.331 μg/ml). LY127935 susceptibility was not influenced by increasing inoculum size, as was ampicillin susceptibility. Combinations of LY127935 and chloramphenicol or ampicillin were not antagonistic in vitro.

Original languageEnglish (US)
Pages (from-to)470-473
Number of pages4
JournalAntimicrobial Agents and Chemotherapy
Volume17
Issue number3
DOIs
StatePublished - 1980

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

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