Objectives: To determine rates of drug resistance to Mycobacterium tuberculosis and associated risk factors, including HIV infection.
Design: Prospective cohort study of patients with pulmonary tuberculosis.
Setting: The study population comprised 28,522 men working on four goldmines in Westonaria, Gauteng. Health care is provided at a 240-bed mine hospital, Gold Fields West Hospital, and its primary health care facilities.
Subjects: All 425 patients with culture-positive pulmonary tuberculosis identified in 1995.
Outcome measures: Tuberculosis drug resistance on enrollment and after 6 months' treatment.
Results: There were 292 cases of new tuberculosis, 77 of recurrent disease and 56 prevalent cases in treatment failure. Two hundred and seven patients (48.7%) were HIV infected. Primary resistance to one or more drugs (9%) was similar to the 11% found in a previous study done on goldminers in 1989. Primary multidrug resistance (0.3%) was also similar (0.8%). Acquired multidrug resistance was 18.1%: 6.5% for recurrent disease and 33.9% in treatment failure cases. Neither HIV infection nor the degree of immunosuppression as assessed by CD4+ lymphocyte counts was associated with drug resistance at the start or end of treatment. New patterns of drug resistance were present in 9 of 52 patients in treatment failure at 6 months, 1 of whom was HIV-infected.
Conclusion: Primary and acquired drug resistance rates are stable in this population and are not affected by the high prevalence of HIV infection.