Efflux Mediated Co-resistance

Antimicrobial resistance is one of the major threats to the global health care facilities. The drug resistant microbes take a heavy toll on the human life resulting in huge losses in terms of economy and human resource. Moreover, with current celerity of mobility, the dissemination of these microbes is relatively easy and swift, making the situation even worse. The rising rate of incidence of ‘superbugs’ that are resistant to all known drugs and dwindling supply of newer antimicrobials, the post-antibiotic era seems an inevitable future. Due to its widespread reach and rapidity, the evolution of antimicrobial resistance (AMR) in bacteria is of particular interest. These microbes resist the action of antimicrobials by various mechanisms, one of which is actively pumping out the antimicrobials from the cellular milieu. This is achieved by specialized proteins, called the efflux pumps, which avoid the effective build-up of antimicrobials and assist survival in otherwise inhibitory concentration of the antimicrobial. These pumps can either be chromosomally encoded or plasmid borne and are generally overexpressed in antimicrobial challenged bacteria. The most striking feature of these efflux pumps is the loss of substrate specificity that enables one pump to efflux out multiple antibiotics. This review focuses on the ability of these pumps to identify multiple substrates and provide selective advantage to the pathogenic bacterial cells.