Evaluation of Multidrug Resistant Loop-mediated Isothermal Amplification Assay for Detecting the Drug Resistance of Mycobacterium tuberculosis

Objective To evaluate multidrug resistant loop-mediated isothermal amplification (MDR-LAMP) assay for the early diagnosis of multidrug-resistant tuberculosis and to compare the mutation patterns associated with the rpoB, katG, and inhA genes at the Chinese Center for Disease Control and Prevention. Methods MDR-LAMP assay was evaluated using 100 Mycobacterium tuberculosis (Mtb) isolates obtained from the National Reference Laboratory for Tuberculosis in China. Phenotypic resistance to isoniazid and rifampicin and whole-genome sequencing served as reference standards. Results The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MDR-LAMP were 85.5%, 93.6%, 96.7%, and 74.4% for the detection of resistance to isoniazid and rifampicin, respectively, and 80.5%, 92.3%, 98.6%, and 41.4% for the detection of Mtb cultured from smear-positive sputum samples, respectively. When DNA sequencing was used as the reference standard, the sensitivity, specificity, PPV, and NPV of MDR-LAMP were 93.1%, 92.3%, 97.2%, and 82.8% for the detection of katG and inhA gene mutations, respectively, and 89.1%, 88.9%, 93.4%, and 81.1% for the detection of rpoB gene mutation, respectively. Conclusion MDR-LAMP is a rapid and accessible assay for the laboratory identification of rifampicin and isoniazid resistance of Mtb isolates.