Relativity Between Gene Mutations And Isoniazid-resistance In Mycobacterium Tuberculosis Isolates And Rapid Detection

Objective Study the relationship between drug-resistant to isoniazid and mutations in Mycobacterium tuberculosis isolates, and rapid classify the gene mutations in isoniazid-resistant clinical Mycobacterium tuberculosis isolates through Macroarray Hybridization Technique. Methods 87 clinical Mycobacterium tuberculosis isolates from Affiliated Hospital of Zunyi Medical College in Guizhou Province were used for drug susceptibility testing,PCR and mutation sequence analysis of katG(409bp) and inhA(175bp) genes. A total of 18 isolates with katG gene 315 mutant side in 87 clinical Mycobacterium tuberculosis isolates, and 15 isolates of wild-type katG gene were used for Macroarray Hybridization based on PCR.According to the preserved sequence of mutant katG gene,3 probes were designed to detect the common mutant sequence in katG gene. Results 87 clinical isolates were proved to be Mtb.30 (34.5%) isolates was resistant to isoniazid,57 (65.5%) isolates were sensitive to isoniazid. Among the 87 clinical Mycobacterium tuberculosis isolates analyzed,21 isolates (24.1%) had mutations in the katG gene;among these 21 isolates,12 isolates had mutation in 315 side.24 isolates (27.6%) had mutations in the inhA gene, and 8 isolates (9.2%) had mutations in both genes. Of 30 isolates,18 (60%) isolates had mutations in the katG and (or) inhA genes. In these mutation isolates,9 (50%) mutations appeared in katG gene,5 (27.8%) in inhA, and 4 (22.2%) in both katG and inhA genes. Two of the mutations in the katG gene (Val230Met and Pro232Gln) were not reported previously and therefore were submitted to the GenBank as new sequences (GQ250582 and GQ250583); After Macroarray Hybridization testing,33 clinical isolates were proved to have katG gene, the concordance with DNA sequence was 93.9%(31/33),the sensiticity and specificity was 90% and 100% compared with DNA sequence. Conclusion Mutations in katG and inhA genes are related to the isoniazid resistance in Mtb and 315 side of katG gene are highly related to isoniazid resistance.The Macroarray Hybridization Technique is a highly sensitive and rapid method for detection of 2 mutations of katG gene,and might be applicable as a basis for further study of the rapid detecting of drur resistance to isoniazid.