title: Antimicrobial susceptibility patterns of the Bacteroides fragilis group in the United States, 1989.
abstract: 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 micrograms/ml and 2 micrograms/ml, respectively. Sulbactam was also tested in a fixed ratio of 1:2. Imipenem, ampicillin+sulbactam, and ticarcillin+clavulanic acid had resistance of less than 1% at breakpoints of 8 micrograms/ml, 16 micrograms/ml, and 64 micrograms/ml, respectively. At 32 micrograms/ml, resistance to cefoxitin, cefotetan, ceftizoxime, and ceftriaxone were 4%, 25%, 26%, and 46%, respectively. Clindamycin resistance was 10% at a breakpoint of 4 micrograms/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 beta-lactam drugs tested as combinations. This finding suggests that beta-lactamase production is the major resistance factor in members of the B fragilis group.
authors.affiliation: Department of Medicine, New England Medical Center, Boston, Massachusetts.
authors.forename: G J
authors.initials: GJ
authors.lastname: Cuchural
authors.forename: D R
authors.initials: DR
authors.lastname: Snydman
authors.forename: L
authors.initials: L
authors.lastname: McDermott
authors.forename: P B
authors.initials: PB
authors.lastname: Iannini
authors.forename: G B
authors.initials: GB
authors.lastname: Hill
authors.forename: T J
authors.initials: TJ
authors.lastname: Cleary
authors.forename: J P
authors.initials: JP
authors.lastname: O'Keefe
authors.forename: C L
authors.initials: CL
authors.lastname: Pierson
authors.forename: J D
authors.initials: JD
authors.lastname: Rihs
authors.forename: S M
authors.initials: SM
authors.lastname: Finegold
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001441:Bacteroides fragilis / Q000187:drug effects*; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests; D014481:United States
chemical_list: D000900:Anti-Bacterial Agents