Involvement of Antimicrobial Drug Efflux Systems in Bacterial Fitness and Virulence

Abstract

Multidrug efflux pumps play an important role in antimicrobial resistance and also serve other functions that are related to bacterial cell communication, stress responses, fitness, and virulence. Although it is challenging to define the natural functions of drug efflux pumps, accumulating evidence has revealed both direct and indirect involvement of multidrug efflux systems in these cellular processes. There is also an intertwined regulation of drug efflux and other cellular systems implying various shared regulators. These features explain diverse effects of multidrug efflux pump status on bacterial functions, including interactions between bacterial species and their hosts. Drug efflux pump contribution to improved fitness and increased virulence of pathogens is supported by numerous examples. This chapter describes the current understanding of the roles of drug efflux pumps (in particular those of Gram-negative bacteria) in bacterial pathogenicity, which further underscores the clinical significance of drug efflux phenomena.