Background. Drug-resistant Mycobacterium tuberculosis has emerged as a
global threat. In resource-constrained settings, patients with a history
of tuberculosis (TB) treatment may have drug-resistant disease and may
experience poor outcomes. There is a need to measure the extent of and
risk factors for drug resistance in such patients.
Methods. From July 2003 through November 2006, we enrolled 410
previously treated patients with TB in Kampala, Uganda. We measured the
prevalence of resistance to first- and second-line drugs and analyzed
risk factors associated with baseline and acquired drug resistance.
Results. The prevalence of multidrug-resistant TB was 12.7% (95%
confidence interval [95% CI], 9.6%–16.3%). Resistance to second-line
drugs was low. Factors associated with multidrug-resistant TB at
enrollment included a history of treatment failure (odds ratio, 23.6;
95% CI, 7.7–72.4), multiple previous TB episodes (odds ratio, 15.6; 95%
CI, 5.0–49.1), and cavities present on chest radiograph (odds ratio,
5.9; 95% CI, 1.2–29.5). Among a cohort of 250 patients, 5.2% (95% CI,
2.8%–8.7%) were infected with M. tuberculosis that developed additional
drug resistance. Amplification of drug resistance was associated with
existing drug resistance at baseline (P ! .01) and delayed sputum
culture conversion (P ! .01).
Conclusions. The burden of drug resistance in previously treated
patients with TB in Uganda is sizeable, and the risk of generating
additional drug resistance is significant. There is an urgent need to
improve the treatment for such patients in low-income countries.
Clinical Infectious Diseases (2008) 47, 1126–1134 [doi: 10.1086/592252]
Rate and Amplification of Drug Resistance among Previously-Treated Patients with Tuberculosis in Kampala, Uganda