It is apparent that in the UTI isolates examined, GyrA and ParC alterations, decreased permeability due to alterations in OMPs and LPS, in conjunction with active efflux play an important role in the fluoroquinolone resistance phenotypes observed. It would be short-sighted to underestimate the effect of efflux-mediated resistance to ciprofloxacin and the other quinolones, even though it generally results in low-level resis- tance. Activation and/or increased expression of efflux pumps as a result of mutations within the global regulator operons, such as marRAB, would play a critical role in determining the success of