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

Abstract

Setting: A gold mining company in the Free State Province of South Africa.

Objective: To document the incidence of and factors associated with drug-resistant tuberculosis (TB) in South African gold miners.

Design: Review of Mycobacterium tuberculosis drug susceptibility records for the period from 1 July 1993 to 30 June 1997.

Results: Over the study period, 2241 miners had culture-positive M. tuberculosis 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 and 1.0% and 2.8% for resistance to at least isoniazid and rifampicin (multidrug resistance). Resistance to streptomycin and ethambutol was uncommon, and rifampicin monoresistance was rare. No significant factors for primary drug resistance were identified. Patients with retreatment pulmonary TB who failed primary TB treatment (versus cure) were significantly more likely to have TB with resistance to any TB drug or MDR (odds ratios respectively 9.82, 95%CI 2.97-33.5, and 18.74, 95%CI 1.76-475). Human immunodeficiency virus (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 the HIV epidemic and increasing TB rates. Directly observed therapy may have contributed to containing the level of drug resistance. Adherence to and completion of treatment are essential to prevent drug resistance and treatment failure, including in situations with high HIV prevalence.