Control of anti-tuberculosis drug resistance in Botswana.

SETTING

Botswana, where in 2000 the prevalence of human immunodeficiency virus (HIV) infection among adults was 38%, and the tuberculosis (TB) rate was 591/100,000. A 1995-1996 survey demonstrated low levels of anti-tuberculosis drug resistance.

OBJECTIVE

Because TB drug resistance may increase rapidly in HIV-infected populations, a second survey was undertaken in 1999 to determine any increase in anti-tuberculosis drug resistance.

DESIGN

Sputum specimens positive for acid-fast bacilli from patients without prior TB treatment (new patients), and all sputum specimens from patients reporting prior TB treatment (retreatment patients) were collected nationwide. Specimens were cultured for Mycobacterium tuberculosis and tested for resistance to isoniazid, rifampicin, ethambutol, and streptomycin.

RESULTS

From January to May 1999, 783 patients were consecutively enrolled from all districts. Of these, 483 (61.7%) were male, the median age was 33 years, and 82% were new patients. Drug resistance occurred in 6.3% of new patients (95 % confidence interval [CI] 4.6-8.6) and 22.8% of retreatment patients (95% CI 16.5-30.1). Resistance to at least isoniazid and rifampicin was found in 0.5% of new (95% CI 0.1-1.3) and 9.0% of retreatment patients (95% CI 5.1-14.5).

CONCLUSION

Anti-tuberculosis drug resistance remains relatively low in Botswana, probably as a result of a well-functioning TB program. Periodic surveys will be essential to adequately determine any significant trend.