Abstract:

Objective To investigate the effectiveness of the line probe assay GenoType^? MTBDRplus in the detection of drug resistance in Mycobacterium tuberculosis.Methods Three hundred and seventy eight Mycobacterium tuberculosis clinical isolates were tested for resistance to rifampicin (RFP) and isoniazid (INH) using the molecular line probe technique, and drug susceptibility testing (“susceptibility testing”) against RFP and INH was performed using conventional proportional assays. Differences in results obtained between the two methods were compared by Chi-square tests using SPSS 13.0 software, P<0.05 being considered statistically significant. The Kappa consistency test was also applied, Kappa≥0.75 indicating better consistency.Results RFP resistance rates obtained by the linear probe and proportional methods, 12.2% (46/378) and 10.6% (40/378), respectively were not significantly different (χ ²=3.60, P>0.05). The overall consistency rate was 97.4% (368/378), the two methods showing good consistency (Kappa=0.87). INH drug resistance rates, 14.3% (54/378) and 12.2% (46/378), respectively, were not significantly different (χ ²=3.20, P> 0.05). Overall consistent rate was 94.7% (358/378), the two methods showing good consistency (Kappa=0.77). Multidrug resistance rates determined by the two methods, 7.4% (28/378) and 7.9% (30/378), respectively, were not significantly difference (χ ²=0.40, P>0.05). The overall consistency rate was 97.4% (368/378), indicating that the two methods show good consistency (Kappa=0.81). The sensitivity and specificity of the linear probe method for detecting RFP resistance was 95.0% (38/40) and 97.6% (330/338), respectively, while that for detection of INH resistance was 87.0% (40/46) and 95.8% (318/332) respectively. The sensitivity and specificity for detecting MDR was 80.0% (24/30) and 98.9% (344/348), respectively.Conclusion Linear probe technology for detecting the drug resistance status of clinical isolates of M.tuberculosis drug resistance is practicable.

Key words: Molecular probe techniques, Tuberculosis, multidrug-resistant, Microbial sensitivity tests, Comparative study