Role of Plasmid Encoded Drug Efflux Pumps in Antimicrobial Resistance
Plasmids, as extrachromosomal genetic mobile elements, have been widely documented to mediate high level bacterial resistance to all major clinically relevant antibiotics and antiseptic agents. The first drug efflux pump discovered in bacteria is plasmid encoded. Naturally occurring drug resistance plasmids are diverse and belong to different incompatibility groups. Multidrug resistance determinants often coexist on the same plasmids with strong linkages to mobile elements such as integrons or transposons. Thus, plasmids play a critical role in the evolution of resistance and in the dissemination of resistant bacteria, which poses a major challenge to antimicrobial therapy. This chapter provides an up to date overview of the plasmid mediated genetic and biochemical mechanisms of antimicrobial resistance with an emphasis on plasmid encoded drug efflux pumps in major pathogens.