Mycobacterium Avium Intracellulare, Mycobacterium Scrofulaceum, Mycobacterium Marinum

‍Nontuberculous mycobacteria species include Mycobacterium avium complex (MAC) (namely M. avium and M. intracellulare), Mycobacterium scrofulaceum, and Mycobacterium marinum. MAC and M. scrofulaceum are commonly found in the environment, including in soil, water, and dust. They can be transmitted through inhalation of contaminated particles or aerosols. M. marinum can infect fish, amphibians, reptiles, and humans, and is usually spread by infected water. M. scrofulaceum causes cervical lymphadenitis, most commonly in children, and M. marinum causes skin infections in aquarium handlers. MAC infections can present as TB-like symptoms in patients with symptomatic lung disease, such as cough, fatigue, night sweats, shortness of breath, and weight loss. This clinical picture is seen in conditions like bronchiectasis and COPD. Disseminated disease of MAC is commonly observed in immunocompromised individuals, particularly advanced HIV patients with a low CD4 count. MAC bacteria often exhibit multidrug resistance. Treatment for MAC infections typically involves a macrolide (such as clarithromycin or azithromycin) combined with ethambutol, and a third agent like rifabutin might be considered. For HIV patients not on antiretroviral therapy with a CD4 count below 50, prophylaxis with a macrolide is recommended, alongside the initiation of ART.