effect of cigarette smoking on sputum smear conversion time among adult new pulmonary tuberculosis patients: a study from iran southeast

background cigarettes smoking is a risk factor for tuberculosis (tb). associations between smoking and tb disease have been reported, but there are few reports on the influence of smoking on the sputum smear and culture conversion time. this study surveyed the possible association between smoking and sputum smear conversion time among new smear-positive pulmonary tuberculosis patients. patients and methods between may 2005 and december 2006, we evaluated smokers and non-smokers patients with pulmonary tb referred to zahedan tuberculosis center (southeastern iran). patients were not immunosuppressed or infected by human immunodeficiency virus (hiv). drug resistant cases were also excluded. results a total of 200 tb patients, including 100 smokers, were evaluated. there was a significant delay in sputum smear conversion time between smokers and non-smokers 2 (53% vs. 10%, respectively, p<0.001) and 3 months following the treatment (19% vs. 2%, respectively, p<0.001). however, there was no significant difference in failure rate (a positive smear at the end of the 5th month of treatment) between two groups (95% vs. 97%). conclusion our results revealed that smoking is significantly associated with a delay in sputum smear conversion time, hence, pulmonary tb cases must be strongly encouraged to cease smoking.