Abstract: Objective To evaluate the application value of three routine detection methods in the laboratory for the diagnosis of Mycobacterium tuberculosis(MTB) and drug-resistant mutations in patients with tuberculosis.
Methods A retrospective study of 246 patients with tuberculosis who were positive for MTB was made. Gene Xpert MTB/RIF(Xpert method), BD960 liquid rapid culture method(BD960 method) combined with rapid drug sensitivity test(drug sensitivity test), and mycobacterial nucleic acid test(TB-DNA method) combined with MTB drug resistance gene test(DNA chip method) tests were performed to assess the detection of three MTB and drug-resistant mutations.
Results The positive detection rate of MTB by BD960 method was lower than that of TB-DNA method and Xpert method, the difference was statistically significant(P＜0.05). There was no significant difference in drug sensitivity test, MTB resistance gene detection and Xpert rifampicin resistance detection rate(P＞0.05). Compared with the rifampicin resistance test results, the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and Youden index of the DNA chip method and Xpert method were 91.30%, 95.32%, 84.00%, 97.60%, 94.47%, 86.63% and 95.65%, 93.57%, 80.00%, 98.77%, 94.01%, 89.22%, The results of rifampin resistance detected by X-Pert and MTB are highly consistent(Kappa value=0.833, 0.840). There was no significant difference in the detection rate of isoniazid resistance between drug sensitivity test and MTB resistance gene detection(P＞0.05).
Conclusion The BD960 method, Xpert method and TB-DNA method can accurately detect MTB in samples. Drug susceptibility test, DNA chip method and Xpert method can analyze the resistance of MTB rifampicin(isoniazid). MTB resistance gene detection and Xpert method have high sensitivity and specificity, which can be applied in MDR-TB control according to the actual needs.

Key words: mycobacterium tuberculosis, drug-resistant, clinical laboratory techniques