Plasmid-mediated colistin-resistance genes: mcr.

Mobile colistin resistance (MCR) is the primary mechanism for colistin resistance and has been disseminated worldwide; this has gained substantial attention and led to policy changes for the use of colistin in food animals in many countries. The global spread of mcr was attributed to the high selective pressure of colistin used in livestock, and the acquisition of mcr by low-copy-number and highly conjugative plasmids. The dramatic decrease of mcr after the colistin-banning policy could be associated with the fitness cost mediated by MCR. Besides mediating resistance to both polymyxins and antimicrobial peptides, MCR is thought to enhance the virulence of bacteria and affect the host immune response. To combat colistin-resistant bacteria, MCR inhibitors have been developed based on the structure of MCR, and other strategies targeting mcr -positive plasmids/strains have also been exploited. Colistin is regarded as a last-line drug against serious infections caused by multidrug-resistant Gram-negative bacterial pathogens. Therefore, the emergence of mobile colistin resistance (mcr) genes has attracted global concern and led to policy changes for the use of colistin in food animals across many countries. Currently, the distribution, function, mechanism of action, transmission vehicles, origin of mcr , and new treatment strategies against MCR-producing pathogens have been extensively studied. Here we review the prevalence, structure and function of mcr , the fitness cost and persistence of mcr -carrying plasmids, the impact of MCR on host immune response, as well as the control strategies to combat mcr -mediated colistin resistance. Colistin is regarded as a last-line drug against serious infections caused by multidrug-resistant (MDR) Gram-negative bacterial pathogens. Therefore, the emergence of mobile colistin resistance (mcr) genes has attracted global concern and led to policy changes for the use of colistin in food animals across many countries. Currently, the distribution, function, mechanism of action, transmission vehicles, origin of mcr , and new treatment strategies against MCR-producing pathogens have been extensively studied. Here we review the prevalence, structure, and function of mcr , the fitness cost and persistence of mcr -carrying plasmids, the impact of MCR on host immune response, as well as the control strategies to combat mcr -mediated colistin resistance. [ABSTRACT FROM AUTHOR]