Susceptibility of the Anaerobic Gram-negative Non-Sporulating Rod, Bilophila wadsworthia to Beta-Lactams, Beta-Lactamase Inhibitors, Meropenem, Metronidaz

Abstract

The susceptibility of eighty-seven strain of Bilophila wadsworthia to five beta-lactams, two beta-lactamase inhibitors, meropenem, metronidazole, clindamycin and two quinolones was determined. Tests were performed by the modified reference agar dilution technique using triphenyltetrazolium chloride for endpoint reading. The test strains showed a reduced susceptibility to the beta-lactams, penicillin G (MIC90 4 micrograms/ml), ampicillin (MIC90 32 micrograms/ml), piperacillin (MIC90 64 micrograms/ml), cephalothin (MIC90 2 micrograms/ml and cefotaxim (MIC90 4 micrograms/ml). The activity of ampicillin was increased by addition of the beta-lactamase inhibitor, sulbactam (MIC90 2 micrograms/ml), as was the activity of piperacillin by the addition of tazobactam (MIC90 4 micrograms/ml) 90.8% of the strains were found to produce beta-lactamase by the nitrocefin tube method. All strains were shown to be highly susceptible to meropenem, metronidazole and clindamycin (MICs < or = 1 microgram/ml). Sparfloxacin (MIC90 1 microgram/ml) and ciprofloxacin (MIC90 0.5 microgram/ml) were found to be active against most of the strains tested.