Cigarette smoking and culture conversion in patients with susceptible and M/XDR-TB.

Background: Tuberculosis (TB) is a leading cause of morbidity and mortality worldwide. Active cigarette smoking may have a significant impact on treatment responses to anti-tuberculosis treatment.
Objective: To ascertain the effect of smoking on Mycobacterium tuberculosis sputum culture conversion rates following treatment initiation in patients with susceptible, multidrug-resistant and extensively drug-resistant TB (M/XDR-TB).
Method: Sputum cultures of smoking and non-smoking patients with pulmonary TB (PTB) treated at a referral centre in Germany were evaluated.
Results: Between January 2012 and March 2017, 247 patients with PTB treated at the Medical Clinic of Research Center Borstel, Borstel, Germany, were included in the study. Of 247 patients, 65 (26.3%) were infected with multidrug-resistant strains of M. tuberculosis (MDR-TB). Sputum culture examinations were performed on a weekly basis. Active smoking ( n = 111; time to culture conversion [TCC] 50.7 days, interquartile range [IQR] 26.5-73.0) and former smoking ( n = 72; TCC 43.1 days, IQR 19.8-56.0) significantly delayed culture conversion rates ( P < 0.001) when compared with never smoking ( n = 64; TCC 33.2 days, IQR 8.0-50.3). Delay in TCC among smoking, non-MDR-TB patients ( n = 138; TCC 47.3 days, IQR 19.0-89.0) was comparable with non-smoking, MDR-TB patients ( n = 20; TCC 53.0 days, IQR 18.0-71.0). The shortest TCC was observed in non-smoking, non-MDR-TB patients ( n = 44; TCC 33.0 days, IQR 10.0-48.5), whereas the longest was seen in smoking, MDR-TB patients ( n = 45; TCC 60.7 days, IQR 33.3-89.0); P < 0.001).
Conclusion: Active cigarette smoking and, to a lesser extent, former cigarette smoking, substantially delayed culture conversion in PTB.