The application of gene chip in detecting the mutation of drug resistant gene in multi-drug resistant Mycobacterium tuberculosis strains / 天津医药

ABSTRACT

Objective To understand the mutation characteristics of drug resistance-associated genes rpoB, katG and inhA in Mycobacterium tuberculosis (MTB) strains using gene chip method, and evaluate its clinical application value. Methods A total of 76 MTB strains were collected from Shijiazhuang area in 2013 to 2014. Gene chip was used to detect the mutations of rpoB, katG and inhA, and the L-J proportion drug susceptibility test was used as the gold standard to evaluate the overall concordance, sensitivity and specificity of gene chip. The consistency of microarray and phenotypic resistance was evaluated by Kappa test. Results Of all the 76 strains detected, 69 harbored mutations in katG/inhA. The predominant mutation site of katG was 315 codon with the mutation rate of 89.9%(62/69), and 5.8%(4/69) carried mutations at inhA-15(C→T), and 4.3%(3/69)carried combined mutations of katG 315 and inhA-15. The rpoB mutations were detected in 73 strains, of which 64.4%(47/73)carried mutations at codon 531, 15.1%(11/73)at codon 526, 12.3%(9/73)at 516 codon, 1.4%(1/73)at 513 codon, 1.4%(1/73)at 533 codon and 5.5%(4/73)had combined mutations. Compared with results from the L-J proportion method, the sensitivity, specificity and concordance rates of gene chip for RFP were 96.1%(73/76), 100%(50/50)and 97.6%(123/126). The sensitivity, specificity and concordance rates of gene chip for INH were 90.8%(69/76), 100%(50/50)and 94.4%(119/126). The sensitivity, specificity and concordance rates of gene chip for MDR-TB were 86.8%(66/76), 100%(50/50) and 92.1%(116/126). Conclusion The predominant mutation loci of MDR strains in Shijiazhuang area are katG315 and rpoB531. Gene chip is a fast and useful tool for clinical diagnosis of MDR strains.