Abstract
Multidrug-resistant mutants of a wild-type Bacteroides fragilis strain (strain ADB77) and a quadruple resistance nodulation division family efflux pump deletion mutant (ADB77 Delta bmeB1 Delta bmeB3 Delta bmeB12 Delta bmeB15) were selected with antimicrobials. Ampicillin, doripenem, imipenem, levofloxacin, and metronidazole selected for mutants from both strains; cefoxitin selected for mutants from strain ADB77 only; and sodium dodecyl sulfate selected mutants from ADB77Delta bmeB1 Delta bmeB3 Delta bmeB12 Delta bmeB15 only. The mutants overexpressed one or more efflux pumps.