耐利福平结核分枝杆菌rpoA、rpoB、rpoC和rpoZ突变的研究

Study on rpoA, rpoB, rpoC and rpoZ mutations in rifampicin-resistant Mycobacterium tuberculosis isolates

目的了解结核分枝杆菌rpoA、rpoB、rpoC和rpoZ突变特征及其与利福平耐药的关系。方法对140株临床分离结核分枝杆菌进行利福平敏感性试验,并对耐利福平株分别进行rpoB耐药决定区及rpoA、rpoB、rpoC及rpoZ全基因测序。结果 140株结核分枝杆菌中57株对利福平耐药。57株耐利福平结核分枝杆菌中,52株(91.2%)存在突变,其中50株为rpoB基因突变,2株为rpoC突变。在rpoB 765、1001、1156位及rpoC 51位发现新的突变位点。结论结核分枝杆菌对利福平耐药主要与rpoB和rpoC基因突变有关。

Objective To characterize mutations in rpoA, rpoB, rpoC and rpoZ genes of Mycobacterium Tuberculosis （MTB） isolates, and determine the correlation between gene mutations and rifampin （RIF） resistance. Methods The drug susceptibility of 140 clinical isolates was examined by using the proportion method. The DNA fragment including the ＂rifampin resistance determination region＂（RRDR） of the rpoB gene from 57 RIF-resistant isolates out of 140 Mycobacterium tuberculosis isolates tested was amplified and sequenced. The entire coding regions for rpoA, rpoB, rpoC and rpoZ genes were amplified and sequenced for those isolates with no mutations detected in the RRDR of rpoB gene. Results Out of 57 RIF-resistant isolates, 50 had mutations in the fragment of rpoB and 2 in the rpoC gene respectively. Three new mutations at codons 765, 1001 and 1156 in the rpoB gene, and one new mutation at codon 51 of the rpoC gene were identified. Conclusion Mutations in rpoB and rpoC genes are associated with RIF-resistance in Mycobacterium tuberculosis. The new mutations identified in this study could provide a basis for further understanding the mechanism of rifampin resistance and the development of rapid molecular diagnostics suitable for specific regions.