Abstract:

Objective To analyze the feasibility of GeneXpert MTB/RIF technology to detect tuberculosis (TB) and resistance to rifampin in basic TB control institutions. Methods Retrospective analysis was performed on all patients with suspected symptoms of TB who visited Changping Institute for Tuberculosis Control and Prevention from January 1st to December 31st, 2019, which was a total of 1719 cases. Sputum smears, Roche solid culture, and GeneXpert tests were performed on the 1719 patients. Among them, 587 patients with other diseases were confirmed by clinical and laboratory test results, 550 patients with inactive TB were diagnosed and 582 active cases were diagnosed. Among the 582 active TB cases, 237 patients had laboratory etiological evidence (the same sputum sample of the same patient was also cultured by Roche and the M. tuberculosis MPB64 antigen was used for strain identification, and the GeneXpert detection system was used as well), was diagnosed as etiological positive patient, and the remaining 345 patients were clinically diagnosed patients. The positive detection rates of sputum specimen of the 237 TB cases by smear, culture and GeneXpert were compared, and rifampin resistance related indexes were compared as well. Chi-square test was used to compare the count data. When the theoretical frequency was lower than 5, the Fisher exact probability method was used for comparison. The difference was statistically significant with P<0.05. Results Of 237 etiologically positive patients, the detection rates were 25.3% (60/237), 79.7% (189/237) and 96.2% (228/237) by smear, culture and GeneXpert, respectively. The detection rate of GeneXpert was significantly higher than that of culture and smear (χ²=249.742, P<0.001; χ²=30.332, P<0.001). Took Roche solid ratio method rifampicin resistance test result as the reference standard, the sensitivity, specificity, positive predictive value, negative predictive value and consistency were 99.6% (232/233), 100.0% (4/4), 100.0% (232/232), 80.0% (4/5) and 99.6% (236/237) respectively. Conclusion GeneXpert has a high detection rate for etiologically positive patients and rifampin resistance. It is of great value to carry out TB detection and rifampin resistant TB detection at the basic level.

Key words: Mycobacterium tuberculosis, Microbial sensitivity tests, Rifampin, Nucleic acid amplification techniques, Laboratory techniques and procedures, Comparative study