The rates of sputum conversion among new smear positive open pulmonary tuberculosis patients treated under directly observed treatment, short course strategy.

Objective: To evaluate effectiveness of directly observed treatment short course (DOTS) by monthly sputum conversion rates at first, second, and third month in newly diagnosed patients of pulmonary tuberculosis (TB) (category-1), and to study patterns of lesions on chest radiographs and their correlation to smear sputum positivity, also to record reaction to Mantoux tuberculin skin test (TST) in active TB patients.

Methods: This prospective cohort study was conducted among 100 newly diagnosed patients of open pulmonary tuberculosis CAT-1, admitted and treated under DOTS, at the Tuberculosis Center, Dammam Medical Complex, Dammam, Kingdom of Saudi Arabia between July to December 2010. Chest radiographs were studied for the patterns of lesions and their correlation to the grades of sputum positivity. Three fasting state sputum specimens were tested on 3 consecutive days by direct smear microscopy at first, second, and third month. As per DOTS, intensive phase treatment was extended for another 4 weeks in those still positive at the end of 2 months. Mantoux TST was performed on all patients with tuberculin purified protein derivative-RT-23 2TU.

Results: The overall sputum conversion rate observed at the first month was 56%, 76% on the second month, and 94% on the third month. Reaction to TST of more than 10 mm was recorded in most of the studied patients (97%).

Conclusion: The DOTS is an appropriate strategy for early and progressive conversion of smear positive patients to break the chain of infection, which is epidemiologically important for the control, elimination, and eradication of TB.