Low levels of drug resistance amidst rapidly increasing tuberculosis and human immunodeficiency virus co-epidemics in Botswana

Abstract

Setting: Botswana, southern Africa, where the tuberculosis (TB) case rate increased by 120% from 1989 to 1996 in spite of a decade of implementation of the directly observed therapy, short-course (DOTS) strategy.

Objective: To determine prevalence of and risk factors for drug-resistant tuberculosis in an epidemic setting.

Design: Systematic national random survey of newly diagnosed pulmonary TB and all patients with TB requiring retreatment during 1995-1996. Interviews were conducted, human immunodeficiency virus (HIV) testing was offered, and drug susceptibility testing was performed for isoniazid, rifampicin, streptomycin and ethambutol.

Results: Resistance to at least one drug was identified in 16 (3.7%) new cases and 18 (14.9%) retreatment cases. One (0.2%) new and seven (5.8%) retreatment cases had resistance to at least both isoniazid and rifampicin (multidrug-resistant TB). Retreatment cases with multidrug-resistant TB were significantly more likely to have worked in the mines in South Africa than were cases with fully susceptible isolates (6/7 [85.7%] versus 32/ 103 [31.1%], odds ratio 13.3, 95% confidence interval 1.5-311.0, P = 0.007). Of 240 patients tested for HIV, 117 (48.8%) were positive; prevalence was similar among new and retreatment cases, and was not a risk factor for drug resistance in either group.

Conclusion: During the HIV and TB co-epidemics in sub-Saharan Africa, DOTS may help to control drug-resistant TB. However, the TB case rate can be expected to continue to climb in spite of the implementation of the DOTS strategy.