RESUMO
Multidrug resistance is a major problem in the treatment of infectious diseases caused by bacteria and fungi. One of the basic mechanisms of resistance is active efflux of distinct drugs from cells. Export of toxic compounds from bacterial cells is mediated by proteins of 5 distinct families: MF, SMR, ABC, RND and MATE. The substrate spectrum of efflux pumps includes antibiotics, chemotherapeutics and detergents. Genes that determine resistance can be located on chromosomes or mobile elements (plasmids, transposons, integrons). The presence of resistance genes on mobile elements enables bacteria to transfer those genes between cells and spread the multidrug resistance phenotype. There are several inhibitors of efflux pumps that are currently in the experimental phase. Proteins that mediate multidrug resistance are also present in fungal cells. They belong mainly to the ABC superfamily of transporters and PDR subfamily. These efflux pumps are widely investigated in Saccharomyces cerevisiae.