title: Bactericidal activity of selected antimicrobial agents against Bilophila wadsworthia and Bacteroides gracilis.
abstract: Bactericidal assays of Bacteroides gracilis (six strains) and Bilophila wadsworthia (12 strains) in brucella broth with appropriate supplements were performed by the time-kill kinetic method. Antimicrobial agents tested were ampicillin/sulbactam (final concentrations, 16/8 micrograms/mL), ticarcillin/clavulanate (128/2 micrograms/mL), imipenem (8 micrograms/mL), cefoxitin (32 micrograms/mL), chloramphenicol (16 micrograms/mL), clindamycin (4 micrograms/mL), and metronidazole (16 micrograms/mL). Although all antimicrobial agents tested inhibited growth of all Bilophila strains during the first 24 hours, bactericidal activity was variable; only metronidazole was uniformly bactericidal. Most strains of Bilophila showed 1-2 log increases in growth at 6 hours with clindamycin and chloramphenicol. With chloramphenicol, some Bilophila strains tested showed regrowth starting at 30 hours. B. gracilis strains were generally more susceptible to all agents tested. Metronidazole, ticarcillin/clavulanate, chloramphenicol, and imipenem were most active. Several strains of B. gracilis were not killed by ampicillin/sulbactam, clindamycin, or cefoxitin. Activity was variable among strains and antimicrobial agents.
authors.affiliation: Research Division, VA Wadsworth Medical Center, Los Angeles, California 90073.
authors.forename: E J
authors.initials: EJ
authors.lastname: Baron
authors.forename: G
authors.initials: G
authors.lastname: Ropers
authors.forename: P
authors.initials: P
authors.lastname: Summanen
authors.forename: R J
authors.initials: RJ
authors.lastname: Courcol
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001439:Bacteroides / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D006089:Gram-Negative Anaerobic Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests / Q000706:statistics & numerical data; D015203:Reproducibility of Results
chemical_list: D000900:Anti-Bacterial Agents