Efflux pumps: their role in antibacterial drug discovery.

The emergence of active efflux as a major causative factor in antibiotic resistance has been one of the most significant trends in antiinfective chemotherapy over the last decade. The phenomenon affects virtually all classes of antibiotics and frequently results in multi-drug resistant phenotypes. This review analyzes efflux pumps of clinical significance and examines their impact on different antibiotic classes relative to other mechanisms of resistance. Progress in strategies to combat efflux-mediated resistance by modification of existing antibiotics or identification of efflux pump inhibitors is also reviewed.