Antimicrobial susceptibility patterns of the Bacteroides fragilis group in the United States, 1989

G. J. Cuchural, D. R. Snydman, L. McDermott, P. B. Iannini, G. B. Hill, T. J. Cleary, J. P. O'Keefe, C. L. Pierson, J. D. Rihs, S. M. Finegold

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9 Scopus citations


A national survey of Bacteroides fragilis group was continued in 1989 for the ninth consecutive year. Seven hundred thirty-nine isolates of B fragilis group from eight centers were tested for susceptibility to 14 antimicrobials. Sulbactam and clavulanic acid, beta-lactamase inhibitors, were tested at a constant concentration of 8 μg/ml and 2 μg/ml, respectively. Sulbactam was also tested in a fixed ratio of 1:2. Imipenem, ampicillin + sulbactam, and ticarcillin + clavulanic acid had resistance of < 1% at breakpoints of 8 μg/ml, 16 μg/ml, and 64 μg/ml, respectively. At 32 μg/ml, resistance to cefoxitin, cefotetan, ceftizoxime, and ceftriaxone were 4%, 25%, 26%, and 46%, respectively. Clindamycin resistance was 10% at a breakpoint of 4 μg/ml. No isolates were resistant to chloramphenicol or metronidazole. Resistance for five B fragilis species to cefoxitin, ceftizoxime, and cefotetan varied greatly among both species and participating institutions. The addition of a beta-lactamase inhibitor increased the potency of the betalactam drugs tested as combinations. This finding suggests that beta-lactamase production is the major resistance factor in members of the B fragilis group.

Original languageEnglish (US)
Pages (from-to)122-136
Number of pages15
JournalClinical Therapeutics
Issue number1
StatePublished - Apr 22 1992

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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