EVOLUTION OF RIFAMPIN RESISTANCE IN HUMAN IMMUNODEFICIENCY VIRUS-ASSOCIATED TUBERCULOSIS

Acquired rifampin resistance without preexisting isoniazid resistance is highly unusual in patients with tuberculosis. The purpose of this r eport is to describe and characterize that unusual pattern of acquired drug resistance in three patients with human immunodeficiency virus ( HIV) infection. The patients originally had Mycobacterium tuberculosis strains that were susceptible to isoniazid and rifampin. During treat ment in two patients and after completion of therapy in the remaining one, each patient developed active, rifampin-resistant, isoniazid-susc eptible tuberculosis. One patient subsequently developed isoniazid res istance also. Studies on patients' M. tuberculosis isolates using IS61 10 restriction fragment length polymorphism typing and rpoB gene seque ncing indicated that rifampin resistance in each patient arose during therapy by an rpoB gene mutation in the original M. tuberculosis isola te. Detection of this unusual drug-resistance phenotype in three patie nts with HIV infection suggests that acquired rifampin resistance is s omehow associated with co-infection due to HIV and tuberculosis.