Infections due to non-tuberculous mycobacteria (NTM)

Abstract

The membership list of genus mycobacterium is ever expanding and it has grown to 95 in year 2003. While leprosy and tuberculosis are specific diseases caused by mycobacteria, other members are usually saprophytes but can be opportunistic and at times deadly pathogens. These other mycobacteria are referred to as atypical mycobacteria, non-tuberculous mycobacteria (NTM) or mycobacteria other than tubercle bacilli (MOTT). These organisms can produce localized disease in the lungs, lymph glands, skin, wounds or bone. Occasionally they may produce disseminated disease. Of the more than 90 known species of NTM, about one third have been associated with disease in humans. The species causing human disease are : Mycobacterium avium, M. intracellulare, M. kansasii, M. paratuberculosis, M. scrofulaceum, M. simiae, M. habana, M. interjectum, M. xenopi, M. heckeshornense, M. szulgai, M. fortuitum, M. immunogenum, M. chelonae, M. marinum, M. genavense, M. haemophilum, M. celatum, M. conspicuum, M. malmoense, M. ulcerans, M. smegmatis, M. wolinskyi, M. goodii, M. thermoresistible, M. neoaurum, M. vaccae, M.palustre, M. elephantis, M. bohemicam and M. septicum. Isolation of these mycobacteria from representative specimens and their rapid identification is very important as the treatment strategy for tuberculosis and other mycobacterioses is different. Several biochemical, chemical (lipid) and molecular techniques have been developed for rapid identification of these species. Along with suggestive clinical features, poor response to antitubercular treatment and repeated isolation of the organisms from the clinical specimens these techniques can help in establishing correct diagnosis. Further, many drugs like rifampicin, rifabutin, ethambutol, clofazimine, amikacin, new generation quinolones and macrolides effective against mycobacterial infections are available that can be used in appropriate combinations and dosage to treat these infections.