rpoB基因点突变与结核分枝杆菌对利福平耐药相关性的研究

目的了解浙江地区分离的结核分枝杆菌临床菌株对利福平（RFP）的耐药率及该菌rpoB基因点突变与RFP耐药性的关系。方法从浙江地区肺结核病人的痰液或咽拭子标本中分离并鉴定结核分枝杆菌72株。采用K-B纸片法和E-试验法检测上述结核分枝杆菌临床菌株对RFP的耐药性。采用PCR检测上述结核分枝杆菌临床菌株rpoB基因携带率。通过对RFP敏感或耐药各10株结核分枝杆菌临床菌株rpoB基因T-A克隆后测序，了解该基因氨基酸序列第516、526和531位点突变情况及其与RFP耐药性的关系。结果38．9％（28／72）结核分枝杆菌临床菌株对RFP耐药。所有结核分枝杆菌临床菌株均携带rpoB基因。1株RFP敏感的结核分枝杆菌临床菌株rpoB基因氨基酸序列中出现S526L点突变。5株RFP耐药的结核分枝杆菌临床菌株rpoB基因氨基酸序列中出现S526L点突变，另5株发生H531D点突变，但均未发现516位氨基酸突变或526和531位氨基酸联合突变。结论浙江地区分离的结核分枝杆菌临床菌株有较高的RFP耐药频率。上述结核分枝杆菌临床菌株对RFP耐药性与rpoB基因氨基酸序列526或531位点突变密切相关。

Correlation between the point mutation of rpoB gene of Mycobacterium tuberculosis and the drug-resistance to rifamycin

To understand the drug-resistance rate of Mycobacterium tuberculosis isolates from Zhejiang province to rifamycin and its correlation with the development of point mutation of rpoB gene, the susceptibility to rifamycin for 72 strains of M.tuberculosis isolated from sputum or throat swab specimens of patients with pulmonary tuberculosis in Zhejiang area was tested by using the K-B paper disk and E-test, and the percentages of carrying the rpoB gene in these isolates were determined by means of PCR assay. The point mutations occurring at amino acid sequences of 516, 526 and 531-residues of rpoB gene and their correlation to rifamycin resistance were detected through sequencing after T-A cloning of this gene. It was found that 38.9% (28/72) of the M. tuberculosis isolates were resistant to rifamycin based on the results of K-B drug-susceptibility and E-test. All these isolated strains of M. tuberculosis carried the rpoB gene, in which one rifamycin-sensitive strain and 5 rifamycin-resistant strains showed point mutation at amino acid sequence S526L residue of the rpoB gene. In addition, another 5 rifamycin-resistant strains exhibited the H531D point mutation. However, no point mutation at 516 amino acid residue or the combined mutation at 526 and 531 amino acid residues could be detected. It is concluded that the frequency of rifamycin-resistant strains of M. tuberculosis isolated in Zhejiang area is quite high, and is closely associated with the point mutations at 525 and 531 amino acid residues of the rpoB gene.