Ans. is 'a' i.e., Mycobacterium avium intraceliulare(Ref: Ananthanarayan, 9th/e, p. 576; Harrison, 18th/e, p. 1548; 17th/e, 1173)* MAC infection is a late complication of HIV infection, occurs when CD4<50ml, in contrast to T.B. which occurs early even with CD4>300ml* Clinical Features:- Disseminated disease with fever, weight loss and night sweats (most common).- Abdominal pain.- Diarrhoea.- Lymphadenopathy.* Diagnosis is made by demonstration of AFB positive mycobacteria in sputum, stool, blood or bone narrow.