title: Efficacy of sulbactam in an in vitro model of mixed aerobic/anaerobic infections.
abstract: Bacterial interactions in mixed infections may interfere with antimicrobial therapy. The in-vitro efficacy of ampicillin alone, combination sulbactam/ampicillin, and metronidazole was studied. Strains of Bacteroides fragilis, Escherichia coli, and Enterococcus faecalis, alone and in association, were tested by means of a broth dilution method. Minimal bactericidal concentrations (MBC) of ampicillin for B. fragilis 74 in association with E. coli 68 were up to 16-fold higher than for B. fragilis 74 alone (256 compared to 16 mg/l), but only 2-fold higher for sulbactam (5 mg/l)/ampicillin (0.5 and 0.25 g/l). Association of B. fragilis 45 and E. faecalis 186 increased ampicillin MBC of E. faecalis 186 from 2 to 16 mg/l, but the combination sulbactam/ampicillin restored activity of ampicillin. In association with E. faecalis, metronidazole MBCs of B. fragilis increased up to 64-fold. Strains of E. faecalis and E. coli were able to destroy 10 mg/l metronidazole within 8 to 20 h. The present experiments demonstrated effectiveness of sulbactam/ampicillin to inhibit beta-lactamases of associated pathogens. Destruction of metronidazole by E. faecalis lends additional support to the use of the combination in aerobic/anaerobic infections including E. faecalis.
authors.affiliation: Abteilung Medizinische Mikrobiologie, Hygiene-Institut der Universität Tübingen, FR Germany.
authors.forename: W R
authors.initials: WR
authors.lastname: Heizmann
authors.forename: F
authors.initials: F
authors.lastname: Heilmann
authors.forename: B
authors.initials: B
authors.lastname: Egeler
authors.forename: H
authors.initials: H
authors.lastname: Werner
mesh_terms: D000667:Ampicillin / Q000627:therapeutic use; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D001421:Bacteria, Anaerobic / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification; D001424:Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology; D004359:Drug Therapy, Combination; D006801:Humans; D066298:In Vitro Techniques; D008795:Metronidazole / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D013407:Sulbactam / Q000494:pharmacology / Q000627:therapeutic use*; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D008795:Metronidazole; D000667:Ampicillin; D001618:beta-Lactamases; D013407:Sulbactam