Abstract: Objective　To study comparatively the application of gene chip and ratio drug sensitive test in detecting Mycobacterium tuberculosis（MTB） resistance to rifampin（RFP） and isoniazid（INH）， and investigate a rapid method for diagnosing multi-drug resistant tuberculosis (MDR-TB). Methods　After isolating 327 strains from Lowenstein-Jensen，the gene mutation of the 8 sites in rpoB，katG and inhA genes related with MTB resistance to RFP and INH was detected， and the drug resistance was determined. Meanwhile， the ratio drug sensitive test was used to detect MTB resistance to RFP and INH， and the coincidence rates of RFP/INN were compared. Furthermore，16 strains randomly from the samples which were not consistent with the results of RFP or/and INH were performed DNA sequencing， and then the coincidence rate with the DNA sequencing was compared.  Results　The coincidence rate of MTB resistance to RFP was 93.27%，but that to INH was 95.11%. The coincidence rate of MTB resistance to RFP and INH was 90.52%. The detection rates of the 2 methods in detecting MDR-TB were 18.65% and 18.96%， respectively. Comparing the gene chip with DNA sequencing，the coincidence rate of RFP drug resistance was 81.25%， and that of INH drug resistance was 100.00%. Comparing the ratio drug sensitive test with DNA sequencing，the coincidence rate of RFP drug resistance was 50.00%，and that of INH drug resistance was 37.50%. Conclusions　The gene chip in detecting MTB resistance to RFP and INH has high sensitivity and specificity， and has an clinical significance in rapid diagnosis of MDR-TB.

Key words: Gene chip, Ratio drug sensitive test, Mycobacterium tuberculosis