Mycobacterium tuberculosis: drug-resistance mechanisms.

Tuberculosis has resurged during the past decade in many industrialized countries, and strains of Mycobacterium tuberculosis that are resistant to one or more of the main antituberculous drugs are emerging. The molecular basis of mycobacterial drug resistance is now beginning to be understood. Resistance derives from mutations in chromosomal genes leading to overproduction, alteration or loss of the drug target.