Efflux and Antibiotic Resistance

Efflux plays a significant role as a mechanism for antibiotic resistance in many important human pathogens. However, the prevalence of efflux-mediated antibiotic 

Both antibiotic-specific and MDR pumps are known to confer clinically relevant resistance [22, 53]. The former are carried on plasmids and transposons. While they can be rapidly spread between various strains, they are at hand only in a proportion of a total population of a given species. Tet and Mef pumps, which confer resistance to tetracycline and macrolides, respectively, in both Gram-positive and Gram-negative bacteria, are clinically important and highly prevalent antibiotic-specific transporters. 

MDR transporters are usually encoded by housekeeping genes as normal constituents of bacterial chromosome and are present in the whole population of a given bacterial species. The basal level of expression of nonspecific multidrug efflux pumps in wild-type cells determines the basal level of antibiotic susceptibility. This innate resistance may still be low enough such that bacteria are susceptible to therapy with a given antibiotic. 

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