Jingnan Zhao,1 Chengyu Qian,2 Youqiao Jiang,1,3 Wangrui He,1 Wenhua Wu1 

1Tuberculosis Control Department, Jiangxi Provincial Center for Disease Control and Prevention, Nanchang, 330029, People’s Republic of China; 2Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing Chest Hospital, Capital Medical University, Beijing, 101149, People’s Republic of China; 3Young Scientific Research and Innovation Team, Jiangxi Provincial Center for Disease Control and Prevention, Nanchang, Jiangxi, 330029, People’s Republic of China

Correspondence: Wangrui He, Tuberculosis Control Department, Jiangxi Provincial Center for Disease Control and Prevention, No. 555, Beijing East Road, Nanchang, Jiangxi, 330029, People’s Republic of China, Email jxcdccbs@126.com

Purpose: In this study, we aimed to determine the transmission pattern of multidrug-resistant tuberculosis (MDR-TB) isolates circulating in Jiangxi Province with whole-genome sequencing (WGS). In addition, we also sought to describe mutational resistome of MDR-TB isolates.
Patients and Methods: A total of 115 MDR-TB isolates determined by the phenotypic proportion method of drug susceptibility testing between January 2018 and December 2022 from provincial drug surveillance (DRS) in Jiangxi were included in our analysis. The demographic data and treatment history were extracted from the National TB Registry System. WGS was used to analyze the genotypic characteristics of drug resistance and transmissions.
Results: About 62.6% of MDR-TB strains were isolated from cases that received previous anti-tuberculosis treatment. According to the WGS results, 96.5% were genotypic MDR-TB, and more than half of MDR-TB isolates tested were also resistant to streptomycin (59.1%), ethambutol (56.5%), and fluroquinolones (53.0%), while resistance to cycloserine and linezolid was lowest, only in two (1.7%) and one (0.9%) isolate, respectively. Ser450Leu in rpoB (57.9%), Ser315Thr in katG (74.1%), Met306Val in embB (40.0%), Lys43Arg in rpsL (75.0%), Ala90Val in gyrA (32.8%) were predominant mutant types among the rifampin-, isoniazid-, ethambutol-, streptomycin-, fluoroquinolones-resistant isolates, respectively. Lineage 2 (East Asian genotype) occurred at the highest frequency with 97 cases (84.3%), followed by lineage 4 (Euro-American genotype) with 18 cases (15.7%). Additionally, 5 clusters consisting of 10 isolates were identified in the present study, demonstrating a clustering rate of 8.7%.
Conclusion: MDR/Rifampicin-Resistant (RR)-TB epidemic in this region is driven by lineage 2 clade that also show higher resistance to other anti-tuberculosis drugs. Lower cluster rates compared with a relatively higher proportion of new MDR-TB cases indicate that a considerable number of MDR-TB cases remain undiagnosed.

Keywords: Mycobacterium tuberculosis, drug resistant, whole-genome sequencing, genetic diversity, transmission dynamics