Objective To evaluate the performance of the two-stage rifampin resistance tuberculosis (TB) detection with multi-color nested real-time fluorescence quantitative polymerase chain reaction (GeneXpert) as the initial test combined with line probe assay and phenotypic drug susceptibility test.
Method Basic information and laboratory test results of 645 pathogen positive pulmonary TB patients registered in our hospital from 2019 to 2022 were collected. According to the “rifampicin-resistant pulmonary tuberculosis diagnostic algorithm”, GeneXpert was used as the initial test for rifampin resistance detection. Then, patients who did received no GeneXpert test or had negative GeneXpert results of Mycobacterium tuberculosis or unknown rifampicin resistance were provided solid culture, then line probe multidrug-resistance assay or broth microdillution test were used for the positive isolates as the second rifampin resistance detection test. Proportion drug susceptibility test to rifampin, isoniazid, levofloxacin, and moxifloxacin were conducted for the rifampicin resistant strains detected in the two-stage rifampin resistance detections. Rifampin resistance detected in the two-stage detections and overall drug resistance patterns of rifampin resistant TB cases were analyzed.
Result In 645 pathogen positive TB patients. 619 received rifampicin resistance detection (95.97%), and the rifampicin resistance rate was 7.59% (47/619). The first stage test contributed to the detection of 87.23% (41/47) of all rifampin resistant cases, while the second stage test contributed to the detection of 12.77% (6/47) of all rifampin resistant TB cases. In the 47 rifampicin resistant TB cases, 37 were cultured positive. Of the 37 cases, 7 were found to be mono rifampin resistant, 26 were resistant to both rifampicin and isoniazid, and 2 were found to be pre-extensive drug resistant indicated by 4 proportion drug susceptibility tests.
Conclusion The two-stage rifampin resistant TB detection with GeneXpert as the initial test combined with culture, line probe assay, and/or phenotypic drug sensitivity test can facilitate the diagnosis of rifampin resistant TB cases.