Setting: Chiang Rai Province in Northern Thailand, where human immunodeficiency virus (HIV) infection has been prevalent since the 1990s.
Objective: To observe the prevalence of drug-resistant tuberculosis (TB) and investigate the factors related to the level of drug resistance in an HIV endemic area.
Design: Population-based surveillance study covering the whole province.
Method: Drug susceptibility testing was performed at the Thai Ministry of Public Health laboratory for all sputum smear-positive TB patients diagnosed in hospitals in Chiang Rai Province over a 25-month period in 1996-1998. Patient characteristics were obtained through interview by trained personnel. HIV testing was performed with informed consent.
Results: Among the 1077 incident patients without previous history of treatment, the proportion of patients with resistance to isoniazid was 13.2%, 10.8% to rifampicin, 15.6% to streptomycin, and 5.8% to ethambutol. Multidrug resistance (MDR), i.e., resistance to at least both isoniazid and rifampicin, was observed in 6.3%. Factors associated with primary MDR-TB were HIV positivity (OR 2.2, 95%CI 1.3-3.9), age <50 years (OR 2.0), and treatment in the provincial hospital (OR 2.3), compared to patients treated in the community and private hospitals. Stratified analysis shows a significantly high prevalence of primary MDR-TB among HIV-positive patients treated in the provincial hospital against HIV-negative patients or HIV-positive patients in other hospitals.
Conclusion: The prevalence of primary MDR-TB in this area was high. It is necessary to strengthen TB control activities in order to reduce the burden of MDR-TB.