Particulate matter is associated with sputum culture conversion in patients with culture-positive tuberculosis

Abstract

Emerging risk factors for tuberculosis (TB) infection, such as air pollution, play a significant role at both the individual and population levels. However, the association between air pollution and TB remains unclear. The objective of this study was to examine the associa- tion between outdoor air pollution and sputum culture conversion in TB patients. In the present study, 389 subjects were recruited from a hospital in Taiwan from 2010 to 2012: 144 controls with non-TB-related pulmonary diseases with negative sputum cultures and 245 culture-positive TB subjects. We observed that a 1 μg/m3 increase in particulate matter of ≤10 μm in aerodynamic diameter (PM10) resulted in 4% higher odds of TB (odds ratio =1.04, 95% confidence interval=1.01-1.08, P<0.05). The chest X-ray grading of TB subjects was correlated to 1 year levels of PM10 (R2=0.94, P<0.05). However, there were no associations of pulmonary cavitation or treatment success rate with PM10. In subjects with TB-positive cultures, annual exposure to ≥50 μg/m3 PM10 was associated with an increase in the time required for sputum culture conversion (hazard ratio =1.28, 95% confidence interval: 1.07-1.84, P<0.05). In conclusion, chronic exposure to ≥50 μg/m3 PM10 may prolong the sputum culture conversion of TB patients with sputum-positive cultures.