Abstract:

Objective To evaluate the clinical application value of second-generation linear probe technique (GenoType MTBDRplus VER 2.0, called “GenoType 2.0”) for rapid detection of resistance to isoniazid (INH) and rifampicin (RFP) in clinical isolates of Mycobacterium tuberculosis (MTB). Methods A total of 6315 sputum specimens from suspected tuberculosis patients in the reference laboratory of Tianjin Tuberculosis Control Center from April 2017 to April 2019 were collected, and 349 strains identified as MTB by smear positive, culture positive and flora positive were served as the research objects. Conventional drug susceptibility testing (DST) and GenoType 2.0 assay were, respectively, used to detect resistance to RFP and INH of culturing-positive specimens. Based on DST as the reference standard, the detection efficiency of GenoType 2.0 assay were evaluated. Results The detection rates of RFP-sensitive, single resistance to RFP and multi-drug resistance to RFP and INH were 86.53% (302/349), 87.97% (307/349) and 86.25% (301/349) in GenoType 2.0; 2.58% (9/349), 2.29% (8/349) and 2.29% (8/349) in DST; and 10.89% (38/349), 9.74% (34/349) and 11.46% (40/349) in GenoType 2.0+DST, respectively, all the comparisons between GenoType 2.0 and DST, GenoType 2.0+DST and GenoType 2.0 or GenoType 2.0+DST and DST did not assign statistical significance (χ²=0.322, P=0.851; χ²=0.112, P=0.946; χ²=0.546, P=0.761). The detection rates of INH-sensitive, single resistance to INH and multidrug resistance to RFP and INH were 79.94% (279/349), 80.23% (280/349) and 79.65% (278/349) in GenoType 2.0; 9.17% (32/349), 9.46% (33/349) and 9.46% (33/349) in DST; and 10.89% (38/349), 10.32% (36/349) and 10.89% (38/349) in GenoType 2.0+DST, respectively, all the comparisons between GenoType 2.0 and DST, GenoType 2.0+DST and GenoType 2.0 or GenoType 2.0+DST and DST did not assign statistical significance (χ²=0.071, P=0.965; χ²=0.017, P=0.991; χ²= 0.061, P=0.970). Compared with DST, the sensitivity, specificity, coincidence rate, Kappa value of GenoType 2.0 to RFP and INH resistance tests were 91.67% (44/48) and 95.89% (70/73), 99.00% (298/301) and 100.00% (276/276), 97.99% (342/349) and 99.14% (346/349), 0.91 and 0.97, respectively. Conclusion The GenoType 2.0 assay has high sensitivity and specificity as well as shorter detection period for the detection of RFP and INH resistance, and thus it can meet the needs of clinical early diagnosis and timely treatment of tuberculosis.

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