Drug resistance and strain lineage of 297 strains of Mycobacterium tuberculosis in Yi ethnic area of Liangshan in Sichuan from 2020 to 2021
Objective To sequence the whole genomes of 297 strains of Mycobacterium tuberculosis(MTB)isolated from areas in Yi Nationality Prefecture of Liangshan from 2020 to 2021,to understand the tuberculosis drug resistance,drug resistance gene mutations and epidemic strains lineages,and to provide scientific reference for tuberculosis prevention and control in this area.Methods A total of 297 strains of Mycobacterium tuberculosis isolated and cultured from Zhaojue County,Yuexi County,Meigu County and Yanyuan County in Liangshan Prefecture during 2020-2021 was sequenced by high-throughput Illumina NovaSeq 6000 next-generation sequencing platform.Drug resistance,resistance mutation,and strain lineage were analyzed using the whole genome sequence analysis platform SAM-TB,and the data were collated and statistically analyzed by using SPSS 25.0 software.Rates were compared using the x2 test,and differences were considered statistically significant at P＜0.05.Results The number of strains without any resistance genes was 234,accounting for 78.79％.The number of strains with any drug resistance was 63,and the total resistance rate was 21.21％.The resistance rate of rifampicin was the highest(12.12％),followed by isoniazid(9.09％).The mono-resistance rate was 15.49％,the multi-drug resistance rate was 3.37％,and the pre-extensively resistance was 1.68％.Resistance genes mutations for clofazimine and bedaquiline were detected,and the extensively resistance rate was 0.67％.Resistance genes mutations for rifampicin were dominated by rpoB_S450L,and for isoniazid is dominated by katG_S315T.The strain lineage was L2 with the most,accounting for 66.67％,followed by L4(31.31％),and there were mixed samples of L2 and L4,L4 and L6.The resistance rate of L2 was higher than that of L4(x2=4.742,P=0.029),and the risk of L2 resistance was 2.079 times that of L4(95％CI:1.066-4.055).Conclusions Tuberculosis drug resistance in this region is milder than in Liangshan,and the epidemic MTBs are L2 and L4 lineage strains,mainly L2,and patients have multiple infections.Tuberculosis prevention and control should be further strengthened in this area to reduce the transmission of Mycobacterium tuberculosis and the emergence of drug resistance.
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