This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'A patient with HIV has diarrhoea with AF +ve organism in stool. The most likely organism is \nSelect and explain. \nA. Mycobacterium avium intracellulare, B. Mycobacterium tuberculosis, C. Mycobacterium leprae, D. Mycoplasmas', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Surprised,\n\nUsually, the mycobacterium is associated with respiratory tract infection.\nIn HIV infections mycobacterium is an important cause of diarrhoeas.\nThe incidence of the extrapulmonary disease is increased in patients with HIV.\n\nWork up in an HIV patient with diarrhoea.\n\nThe initial evaluation of a patient with HIV infection and diarrhoea includes:-\nA set of stool examination including culture, examination for ova and parasites. and\nExamination for Clostridium difficile toxin.\nApproximately 50% of the time this workup will demonstrate infection with pathogenic bacteria, mycobacteria or protozoa.\nAFB +ve organism suggests the presence of Mycobacterium.\nWe have two options to choose from either mycobacterium. T.B. or mycobacterium avium intracellulare.\nBoth mycobacterium T.B. and M.A.C. can cause diarrhoea in patients with HIV and obviously, both of them are acid-fast, So, which one to choose from.\nI am in favour of Mycobacterium avium intracellular.\nMAC infections are more likely to cause diarrhoea.\nThe presumed portals of entry in MAC are respiratory and gastrointestinal tract.\nWhile discussing HIV patients with diarrhoea.\xa0\xa0Harrison Says -"Abdominal pain and diarrhoea may be seen with MAC infection."\nThus it seems MAC infection is more likely to cause diarrhoea.\nBut still, I am not sure of the answer.\nThe incidence of Mycobacterium T.B. is more than the incidence of MAC in HIV, so mycobacterium T.B. should account for the greater number of diarrhoeal cases in H.I.V.', 'role': 'assistant'}]