OBJECTIVE: To investigate the prevalence of primary drug-resistant tuberculosis (TB) and associated risk factors in China. We also explored factors contributing to the transmission of multidrug-resistant tuberculosis (MDR-TB). METHODS: A total of 2794 representative, Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TB were analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. RESULTS: Among 2794 Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2% and the prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs. The 93 primary MDR-TB isolates were classified into six sublineages, of which, 75 (80.6%) isolates were the RD105-deleted Beijing lineage. The largest sublineage included 65 (69.9%) isolates with concurrent deletions of RD105, RD207, and RD181. Twenty-nine (31.2%) primary MDR strains grouped in clusters; MDR isolates in clusters were more likely to have S531L rpoB mutation. CONCLUSION: This study indicates that primary drug-resistant TB and MDR-TB strains are prevalent in China, and multiple measures should be taken to address drug-resistant TB.
OBJECTIVE: To investigate the prevalence of primary drug-resistant tuberculosis (TB) and associated risk factors in China. We also explored factors contributing to the transmission of multidrug-resistant tuberculosis (MDR-TB). METHODS: A total of 2794 representative, Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TB were analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. RESULTS: Among 2794 Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2% and the prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs. The 93 primary MDR-TB isolates were classified into six sublineages, of which, 75 (80.6%) isolates were the RD105-deleted Beijing lineage. The largest sublineage included 65 (69.9%) isolates with concurrent deletions of RD105, RD207, and RD181. Twenty-nine (31.2%) primary MDR strains grouped in clusters; MDR isolates in clusters were more likely to have S531L rpoB mutation. CONCLUSION: This study indicates that primary drug-resistant TB and MDR-TB strains are prevalent in China, and multiple measures should be taken to address drug-resistant TB.