Abstract: Objective To evaluate the value of tuberculosis specific antigen (TB-SA) antibody detection kit in the diagnosis of tuberculosis. Methods Nine hundred and forty-four pulmonary tuberculosis suspects were continually recruited from April 2012 to October 2012 in 3 district’s TB centers from Tianjin city, Shandong province and Henan province, respectively，110 healthy people were enrolled at the same time. Sputum and serum specimen from all cases were collected for Ziehl-Neelsen staining smear, traditional mycobacterium culture and TB-SA antibody test. PPD skin test and chest X-ray were also examined to all cases. The data were entered separately by 2 people in sites and analyzed by national TB reference laboratory. Results Among 755 active TB patients, the positive rate of TB-SA antibody test were 74.8% (565/755, 95%CI: 71.7%-77.9%), significantly higher than smear (25.6%, 193/755，χ²=366.59, P<0.0001) and culture (39.6%, 299/755, χ²=190.12，P<0.0001); its specificity and positive predictive value were 97.3% (95%CI: 94.3%-100.3%) and 92.3% (95%CI: 90.2%-94.4%), respectively. Among culture-positive TB patients, the sensitivity of TB-SA antibody test was 88.5% (95%CI: 84.8%-92.2%). However, the sensitivity of TB-SA antibody test was 68.0% (95%CI: 63.7%-72.3%) among smear- and culture-negative TB patients. Conclusion TB-SA antibody test has significantly higher positive rate than smear and conventional culture, and can be used for the diagnosis of TB patient especially smear- and culture-negative TB patients. In addition, it can be used for healthy screening examination.

Key words: Tuberculosis, pulmonary/diagnosis, Bacterial proteins, Antibodies, bacterial, Reagent kits, diagnostic