Molecular characterization of para-aminosalicylic acid resistant Mycobacterium tuberculosis clinical isolates in southwestern China Ming Luo,1 Kun Li,1 Huizheng Zhang,1 Xiaofeng Yan,2 Jing Gu,3 Zhen Zhang,4 Yu Chen,5 Jungang Li,1 Jing Wang,1 Yaokai Chen11Central Laboratory, Chongqing Public Health Medical Center, Chongqing 400036, People’s Republic of China; 2Department of Tuberculosis, Chongqing Public Health Medical Center, Chongqing 400036, People’s Republic of China; 3Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People’s Republic of China; 4Department of Pharmacy, Chongqing Public Health Medical Center, Chongqing 400036, People’s Republic of China; 5Department of Medical Records, Chongqing Public Health Medical Center, Chongqing 400036, People’s Republic of ChinaPurpose: The aim of this study is to investigate para-aminosalicylic acid (PAS) resistance-related gene mutations in clinical Mycobacterium tuberculosis (MTB) isolates and analyze the associated risk factors in southwestern China.Patients and methods: Total 122 PAS-resistant and 55 PAS-susceptible clinical isolates were obtained from Chongqing Public Health Medical Center between April 2014 and January 2018. Drug susceptibility test was performed, and the PAS resistance-related genes were sequenced.Results: PAS-resistant strains were more likely to resist streptomycin (OR: 9.5, 95% CI: 3.87-23.3; P