Efflux pump that mediates resistance to quinolone-type antibiotics. Inactivation of the gene causes a significant reduction in the surface-associated motility and virulence (PubMed:28507065). Mutant has 2- to 4-fold higher susceptibility to novobiocin and trimethoprim, and 8- to 32-fold higher susceptibility to the quinolone-type antibiotics nalidixic acid, levofloxacin and ciprofloxacin (PubMed:29941648). Mutation does not affect susceptibility to beta-lactams, aminoglycosides, macrolides and polymyxins (PubMed:29941648). Belongs to the major facilitator superfamily.