Abstract:

Objective To evaluate the ability of GenoType MTBDR plus assay (a linear probe hybridization technology, hereinafter referred to as “HAIN technology”) for detection of drug resistance in Mycobacterium tuberculosis in Shenzhen. Methods Using HAIN technology, the drug resistance of 1140 clinical isolates which were from Shenzhen Drug Resistance Monitoring Project in 2014-2016 (conducted in Shenzhen Center for Chronic Disease Control and Shenzhen District Chronic Disease Prevention and Treatment Institute) were tested. The traditional proportional drug susceptibility testing (DST) was used as standard to evaluate the capability of HAIN technology in detecting drug resistance. The McNemar test was used to compare the detection results. The sensitivity and specificity were used to evaluate the authenticity. The positive predictive value (PPV) and negative predictive value (NPV) were used to evaluate the application value of HAIN technology, and Kappa test was used to evaluate the consistency of the detection results of the two methods. Results The results of proportional DST showed that 123 and 75 cases were resistant to isoniazid and rifampicin, respectively, and 52 cases were resistant to multidrug. The HAIN technique detected 120 cases of isoniazid resistance, 79 cases of rifampicin resistance, and 52 cases of multidrug resistance (MDR). No significant difference was detected between the two methods (McNemar test, P values were 0.250, 0.219 and 1.000, respectively). Taking proportional DST as standard, the sensitivity and specificity of HAIN technique for the detection of isoniazid resistance were 97.6% (120/123) and 100.0% (1017/1017), the PPV and NPV were 100.0% (120/120) and 99.7% (1017/1020), and the Kappa value was 0.986. The sensitivity and specificity of HAIN technique for the detection of rifampin resistance were 98.7% (74/75) and 99.5% (1060/1065), the PPV and NPV were 93.7% (74/79) and 99.9% (1060/1061), and the Kappa value was 0.958. The sensitivity and specificity of HAIN technique for the detection of MDR were 96.2% (50/52) and 99.8% (1086/1088), the PPV and NPV were 96.2% (50/52) and 99.8% (1086/1088), and the Kappa value was 0.960. The results of HAIN technique demonstrated that the most frequent mutation in the rifampicin-resistant gene, rpoB was wild-type band 8 deletion and S531L site mutation (58.7%, 44/75), followed by wild-type band 7 deletion and H526Y site mutation (10.7%, 8/75) and wild-type band 2 deletion (10.7%, 8/75); the most frequent mutation in the isoniazid-resistant genes was wild-type band 1 deletion and S315T1 site mutation in katG (70.8%, 85/120), followed by wild-type band 1 deletion and C15T site mutation in inhA (18.3%, 22/120). Conclusion With its high sensitivity and specificity, GenoType MTBDR plus assay (HAIN technology) is a promising rapid method to detect isoniazid and rifampicin resistance in Mycobacterium tuberculosis strains.

Key words: Mycobacterium tuberculosis, Molecular probe techniques, Tuberculosis, multidrug-resistant, Evaluation studies as topic