title: Analysis of trends in antimicrobial resistance patterns among clinical isolates of Bacteroides fragilis group species from 1990 to 1994.
abstract: Antimicrobial resistance, including plasmid-mediated resistance, among Bacteroides fragilis group species is well documented. A 5-year (1990-1994) prospective, eight-center survey of 3,177 clinical isolates of Bacteroides species was undertaken to review trends in resistance, using the breakpoints for full and intermediate susceptibility established by the National Committee for Clinical Laboratory Standards. No documented resistance to either metronidazole or chloramphenicol was found in this survey. Among B. fragilis isolates virtually no resistance was seen to imipenem, meropenem, ampicillin/sulbactam, piperacillin/tazobactam, or ticarcillin/clavulanate. Significant increases in resistance among B. fragilis isolates to cefotetan, ceftizoxime, and clindamycin (p < .01) were noted. Resistance to cefoxitin remained unchanged. Among the non-fragilis species of the B. fragilis group, there was virtually no resistance to imipenem, meropenem, chloramphenicol, or metronidazole. The three beta-lactamase inhibitors had increasing levels of resistance, although 95%-98% of strains were susceptible (p < .05). There was a significant decline in cefoxitin, cefmetazole, and clindamycin activity over time against these strains (p <.01). There was a significant (P < .001) increase in geometric mean minimum inhibitory concentration for most drugs and species tested from 1990 to 1994. Clusters in the eight institutions could not account for this rise in resistance. This survey demonstrates that rates of resistance of B. fragilis and non-fragilis species of B. fragilis group are increasing.
authors.affiliation: Department of Medicine, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Snydman
authors.forename: L
authors.initials: L
authors.lastname: McDermott
authors.forename: G J
authors.initials: GJ
authors.lastname: Cuchural
authors.forename: D W
authors.initials: DW
authors.lastname: Hecht
authors.forename: P B
authors.initials: PB
authors.lastname: Iannini
authors.forename: L J
authors.initials: LJ
authors.lastname: Harrell
authors.forename: S G
authors.initials: SG
authors.lastname: Jenkins
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: V L
authors.initials: VL
authors.lastname: Yu
authors.forename: S M
authors.initials: SM
authors.lastname: Finegold
authors.forename: S L
authors.initials: SL
authors.lastname: Gorbach
mesh_terms: D001439:Bacteroides / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D001442:Bacteroides Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000302:isolation & purification; D003625:Data Collection; D004352:Drug Resistance, Microbial; D006801:Humans; D011446:Prospective Studies; D013045:Species Specificity; D013997:Time Factors; D014481:United States / Q000453:epidemiology