Active Efflux of Norfloxacin by Bacteroides fragilis

Abstract
Norfloxacin was actively pumped out by Bacteroides fragilis , which is intrinsically resistant to most fluoroquinolones. Reserpine moderately inhibited the efflux. A one-step spontaneous mutant had increased resistance to norfloxacin, ethidium bromide, and puromycin, a result suggesting that the efflux is catalyzed by a multidrug pump with specificity similar to that of NorA/Bmr.