Drug-resistant tuberculosis in South African gold miners: incidence and associated factors

SETTING: A gold mining company in the Free State Province of South Africa. OBJECTIVE: To document the incidence of and factors associated with drug-re sistant tuberculosis (TB) in South African gold miners. DESIGN: Review of Mycobacterium tuberculosis drug susceptibility records fo r the period from 1 July 1993 to 30 June 1997. RESULTS: Over the study period, 2241 miners had culture-positive M. tubercu losis pulmonary disease where isolates were tested for drug susceptibility to the four primary anti-tuberculosis drugs. The proportions of primary and acquired drug resistance were respectively 7.3% and 14.3% for isoniazid an d 1.0% and 2.8% for resistance to at least isoniazid and rifampicin (multid rug resistance). Resistance to streptomycin and ethambutol was uncommon, an d rifampicin monoresistance was rare. No significant factors for primary dr ug resistance were identified. Patients with retreatment pulmonary TB who f ailed primary TB treatment (versus cure) were significantly more likely to have TB with resistance to any TB drug or MDR (odds ratios respectively 9.8 2, 95%CI 2.97-33.5, and 18.74, 95%CI 1.76-475). Human immunodeficiency viru s (HIV) infection was not significantly associated with primary or acquired drug resistance, and there was no trend of increasing resistance over time . CONCLUSION: Anti-tuberculosis drug resistance has remained stable despite t he HIV epidemic and increasing TB rates. Directly observed therapy may have contributed to containing the level of drug resistance. Adherence to and c ompletion of treatment are essential to prevent drug resistance and treatme nt failure, including in situations with high HIV prevalence.