Rifamycin-resistant Mycobacterium tuberculosis in the highly active antiretroviral therapy era: a report of 3 relapses with acquired rifampin resistance following alternate-day rifabutin and boosted protease inhibitor therapy.

Rifamycin-resistant Mycobacterium tuberculosis infection (i.e., by a strain of M. tuberculosis that is only resistant to rifamycins) occurs disproportionately among patients infected with the human immunodeficiency virus (HIV) who have a low CD4 cell count. We observed 3 genetically confirmed cases of relapse with rifamycin-resistant M. tuberculosis infection following concurrent treatment with rifabutin (dosage, 150 mg every other day) and a ritonavir-boosted HIV protease inhibitor during a prior episode of drug-susceptible tuberculosis. Higher doses of rifabutin and a ritonavir-boosted HIV protease inhibitor as treatment for tuberculosis should be studied further.