- Jinyou Qi: Department of Laboratory Medicine, Huai'an Tumor Hospital Jiangsu, China.
- Wei Fan: Department of Laboratory Medicine, Huai'an Tumor Hospital Jiangsu, China.
OBJECTIVE: To investigate the clinical value of molecular biology (xpert MTB/RIF) combined with a liquid mycobacterium culture tube (MGIT) in the clinical examination of Mycobacterium tuberculosis (MTB).
METHODS: A total of 782 patients with suspected pulmonary tuberculosis who came to our hospital from February 2018 to February 2020 were selected as the research subjects. Sputum samples of all patients were taken in the morning, and BACTEC MGIT culture and xpert MTB/RIF, Lowenstein-Jenden (L-J) culture and acid fast staining microscopy were used respectively to detect the sputum samples. The positive samples were cultured, and the bacteria identification and liquid drug sensitivity test were carried out. We also analyzed the value of xpert MTB/RIF combined with MGIT culture method in the clinical testing of MTB.
RESULTS: (1) Among the 782 suspected patients, 405 cases were diagnosed with pulmonary tuberculosis and 377 cases were non tuberculosis patients. The sensitivity of smear microscopy was 17.28% (70/405), the specificity was 98.94% (373/377), and the average time was 3.05 h. The sensitivity of L-J culture test was 20.49% (83/405), the specificity was 97.61% (368/377), and the average time was 28.58 h. The sensitivity of MGIT culture test was 38.02% (154/405), the specificity was 96.82% (365/377), and the average time was 11.23 h. The sensitivity of xpert MTB/RIF test was 36.54% (148/405), the specificity was 99.46% (375/377), and the average time was 2.03 h. The sensitivity of MTB/RIF + MGIT test was 42.47% (172/405), the specificity was 96.02% (362/377), and the average time was 11.29 h. The sensitivity of MTB/RIF combined with MGIT culture was significantly higher than that of smear microscopy and L-J culture (χ=61.31, 45.33, P<0.001). (2) The average culture time of 13 smear negative xpert MTB/RIF negative specimens was 17.02 days. The average culture time of 82 smear negative xpert MTB/RIF positive samples was 14.12 days. The average culture time of 77 smear positive xpert MTB/RIF positive samples was 7.45 days. (3) The sensitivity of Xpert MTB/RIF test for rifampicin resistance is 100% (11/11), and the specificity is 91.14% (144/158).
CONCLUSION: The method of molecular biology combined with MGIT has a high sensitivity and specificity for clinical diagnosis of MTB.