Snapshot A 43-year-old woman presents to the emergency room for fevers and a chronic cough. She has a history of HIV infection and has been using antiretrovirals intermittently. She recently lost her job and has been spacing out her medications in hopes of making it last. She is also currently homeless and relies on homeless shelters around the city. She reports that she has been having low-grade fevers, night sweats, and cough. A chest radiograph shows a cavity in the apex of the right upper lobe and hilar adenopathy. She is started on multi-drug anti-tuberculosis therapy, including rifabutin. (Tuberculosis) Introduction Drugs rifampin 4 Rs login to view 4 more bullets rifabutin less CYP450 stimulation Mechanism of action inhibits DNA-dependent RNA polymerase penetrates tissue to reach granulomas Mechanism of resistance mutations in RNA polymerase to prevent drug from binding Clinical use rifampin Mycoplasma tuberculosis (TB) login to view 1 more bullet Mycoplasma leprae login to view 1 more bullet Neisseria meningitidis login to view 1 more bullet Haemophilus influenzae type b login to view 1 more bullet rifabutin Mycoplasma avium-intracellulare login to view 1 more bullet HIV infection login to view 1 more bullet Adverse effects hepatotoxicity (hepatitis) ↑ CYP-450 red/orange body fluids (benign) acute interstitial nephritis