Chapter 80 - The Mycobacterium avium complex and slowly growing mycobacteria

Abstract

Members of the Mycobacterium avium complex (MAC), including M. avium and M. chimaera, are representatives of over 200 species of nontuberculous mycobacteria (NTMs) that are opportunistic pathogens whose source for human infection is the environment. NTMs are normal inhabitants of soils, natural waters, drinking water distribution systems, and household plumbing. NTMs cause both community- and healthcare-associated infections, including pulmonary, dermal, lymph node, and disseminated infections. Risk factors for NTM disease include preexisting lung damage, cystic fibrosis, and immunodeficiency. In addition, taller, slender, older women are at risk for NTM pulmonary disease. The prevalence of NTM disease is increasing at a rate of 5% per year, currently at 15/100,000 individuals in the United States. Much of the ecology and epidemiology of the MAC and other NTMs can be explained by the ramifications of their lipid-rich outer membrane, including disinfectant-, antibiotic-, and desiccation resistance to disinfectants and commonly used antibiotics. Antibiotic treatment is of long duration and requires multidrug regimens. Fortunately, guidelines for the diagnosis and treatment of NTM infection are available.