Background: Drug-resistant tuberculosis (DR-TB) is a serious threat in developing countries where the prevalence of both HIV and TB are high. Antiretroviral therapy (ART) has been more accessible in these countries. The present study aimed to determine the impact of ART on the prevalence of DR-TB among HIV/TB co-infected patients.
Material and Method: A retrospective cohort study was conducted among HIV-infected patients with cultureproved TB from 1999 to 2004. Susceptibilities of Mycobacterium tuberculosis to antituberculous drugs and rate of ART use were studied.
Results: There were 225 patients, mean age 35.8 years, 72.4% male and median CD4 44 cells/mm3. Patients who had received ART increased from 18.5% in 1999 to 92.1% in 2004 (p<0.001). The prevalence of DR-TB in the years 1999 and 2004 were 48% and 7.9%, respectively (p<0.001). The prevalence of isoniazid- and rifampicin-resistance significantly declined in 2004 when compared with those in 1999 (p<0.05).
Conclusion: The declines in the prevalence of DR TB, INH- and RFP-resistance in HIV/TB co-infected patients are possibly attributable to the use of ART. In addition to the survival benefit from ART in HIV-infected patients, increasing use of ART among HIV-infected patients may eliminate DR-TB in this population.

Keywords: HIV, Tuberculosis, Drug resistance, Prevalence, Antiretroviral therapy