Abstract:

Objective To explore the clinical value of micropore-plate method, real-time fluorescent PCR melting curve technology (melting curve method), multicolor nested real-time fluorescence PCR detection technology (Xpert method) and Roche drug sensitivity test (L-J drug sensitivity test, referred to as proportional method) in rapid screening multidrug-resistant tuberculosis (MDR-TB). Methods From the hospital information system of Chongqing Public Health Medical Center during July 2014 to March 2018, patients who were diagnosed as TB and had the rifampicin and/or isoniazid resistance data by the Micropore-plate, melting curve, Xpert and/or proportional method were screened. The micropore-plate and proportional method were conducted by using positive isolates, and the melting curve and Xpert method were conducted using patient specimens. A total of 1488 patients with both micropore-plate and proportional drug resistance test results were included in the study. Among them, 341 patients underwent micropore-plate + proportional + Xpert methods to detect rifampicin resistance, and 87 patients underwent micropore-plate + proportional + melting curve methods to detect rifampicin resistance, and 66 cases were tested by micropore-plate + proportional + melting curve methods for isoniazid resistance. Taking the proportional method as the standard, SPSS 13.0 software was used to calculate the sensitivity, specificity, coincidence rate and Kappa value of rifampicin and/or isoniazid resistance by micropore-plate, melting curve and Xpert method. Results Taking the proportional method as the standard, the sensitivity, specificity, positive predictive value, negative predictive value, coincidence rate and Kappa value of rifampicin resistance test were 97.2% (731/752), 96.9% (713/736), 96.9% (731/754), 97.1% (713/734), 97.0% (1444/1488) and 0.94 by micropore-plate method, 97.2% (140/144), 94.9% (187/197), 93.3% (140/150), 97.9% (187/191), 95.9% (327/341) and 0.92 by Xpert method, and 97.1% (33/34), 84.9% (45/53), 80.5% (33/41), 97.8% (45/46), 89.7% (78/87) and 0.79 by melting curve method, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, coincidence rate and Kappa value of isoniazid resistance test were 94.8% (751/792), 95.7% (667/697), 96.3% (751/780), 94.2% (667/708), 97.9% (1418/1448) and 0.91 by micropore-plate method and 97.3% (36/37), 86.2% (25/29), 90.0% (36/40), 96.2% (25/26), 92.4% (61/66) and 0.84 by melting curve method. Conclusion Micropore-plate, melting curve and Xpert method have high sensitivity and specificity in detecting rifampicin and/or isoniazid resistance, which are suitable for rapid screening of MDR-TB. The Micropore-plate method also shows the minimum drug concentration of each drug, which provides a reference for the selection of clinical dosage.

Key words: Mycobacterium tuberculosis, Microbial sensitivity tests, Laboratory techniques and procedures, Tuberculosis,multidrug-resistant, Sensitivity and specificity, Comparative study