Abstract:

Objective To explore the clinical value of simultaneous amplification and testing (SAT) in the auxiliary diagnosis of extrapulmonary tuberculosis (TB). We collected abscess fluid or surgical removal tissue samples at the lesion site of inpatients in Department of Tuberculosis, General Surgery and Orthopaedic Surgery of Chongqing Public Health Medical Center between Jan. 2016 and Dec. 2017. Based on the medical records regarding the results of extrapulmonary TB diagnosis, the extrapulmonary TB samples were set as experimental group, and nontuberculous samples as control group. All samples were pretreated by kit manufacturer’s instruction then cultured on solid Lowenstein-Jensen slants and in BACTEC MGIT 960 liquid, and were detected with SAT method. Identification of strains were conducted for specimens with culture-positive and SAT-negative results. The sensitivity, specificity and clinical value of SAT detection for extrapulmonary TB were analyzed, taking the culture method and clinical diagnosis as standards, respectively. The analyses were performed using SPSS 13.0 software. The categorical data were analyzed by χ ² test, and the difference was statistically significant at P<0.05. Among the 127 culture-positive specimens in the experimental group, 107 were positive and 20 were negative by TB-SAT detection. For the 306 culture-negative specimens in the experimental group, 73 were positive and 233 were negative by TB-SAT detection. In the control group, one specimen was positive by culture method and negative by TB-SAT test; the remaining 48 specimens were negative for both culture and TB-SAT method. Compared with the culture method, the sensitivity and specificity of the TB-SAT method were 83.6% (107/128) and 79.4% (281/354), respectively. Meanwhile, compared with the clinical diagnosis of patients, the sensitivity and specificity of the culture method were 29.3% (127/433) and 98.0% (48/49), respectively; and the sensitivity and specificity of the TB-SAT test were 41.6% (180/433) and 100.0% (49/49). The positive rate of culture method was 29.3% (127/433), and the positive rate of SAT method was 41.6% (180/433); the difference was statistically significant (χ ²=14.17, P<0.05). Compared with other methods used in this article, TB-SAT has the advantage of higher detection rate, sensitivity, and specificity as well as more convenient and rapid in diagnosis of extrapulmonary TB.

Key words: Mycobacterium tuberculosis, Nucleic acid amplification techniques, Laboratory techniques and procedures, Comparative study, Extrapulmonary tuberculosis