title: Role of mycobacterial efflux transporters in drug resistance: an unresolved question.
abstract: Two mechanisms are thought to be involved in the natural drug resistance of mycobacteria: the mycobacterial cell wall permeability barrier and active multidrug efflux pumps. Genes encoding drug efflux transporters have been isolated from several mycobacterial species. These proteins transport tetracycline, fluoroquinolones, aminoglycosides and other compounds. Recent reports have suggested that efflux pumps may also be involved in transporting isoniazid, one of the main drugs used to treat tuberculosis. This review highlights recent advances in our understanding of efflux-mediated drug resistance in mycobacteria, including the distribution of efflux systems in these organisms, their substrate profiles and their contribution to drug resistance. The balance between the drug transport into the cell and drug efflux is not yet clearly understood, and further studies are required in mycobacteria.
authors.affiliation: Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Edda
authors.initials: E
authors.lastname: De Rossi
authors.forename: José A
authors.initials: JA
authors.lastname: Aínsa
authors.forename: Giovanna
authors.initials: G
authors.lastname: Riccardi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D024881:Drug Resistance, Bacterial; D006801:Humans; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000187:drug effects* / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins