A review of the molecular mechanisms of drug efflux in pathogenic bacteria: A structure-function perspective

Pathogenic and opportunistic bacteria which are causative agents of infectious disease and harbor effective drug resistance mechanisms may confound treatment in human clinical medicine. Of the various antimicrobial agent resistant mechanisms, active efflux by secondary active transporter systems, called drug efflux pumps, are commonly found within infectious disease causing bacteria. These secondary active drug efflux systems are energized by cation gradients and may have single or multiple drug substrates. It is these multidrug efflux systems that compromise chemotherapeutic efforts against multiple drug resistant bacteria. Close scrutiny of these multidrug efflux systems may provide useful molecular information for potential modulation in order to reduce the conditions that foster bacterial drug resistance and thus possibly restore clinical efficacy of antimicrobial agents. This chapter focuses on key bacterial secondary drug efflux pump systems from a molecular perspective.