TB-SA antibody test for diagnosis and monitoring treatment outcome of sputum smear negative pulmonary tuberculosis patients.

The objectives of this study were to evaluate the suitability of the TB-SA antibody test to diagnose tuberculosis in sputum smear negative (SS-) pulmonary tuberculosis (TB) patients and its applicability for monitoring treatment outcomes in these patients. This study was conducted in three counties/districts in Chongqing Municipality, Liaoning Province, China between June 2005 and June 2007. A total of 432 SS suspected pulmonary TB patients were recruited and their blood was collected prior to treatment, at the end of 1 month of treatment, 2 months of treatment and 6 months of treatment (E6MT). The serum samples were analyzed with a TB-SA antibody test kit. Of the 432 SS suspected pulmonary TB patients, serum samples were obtained at all time points in 316 patients and analyzed. The 316 patients were divided into three groups according to sputum smear and sputum culture results and the chest X-ray results before treatment and at E6MT. Ten point four percent were SS-/culture positive (C+), 73.1% were SS-/culture negative (C-) with X-rays abnormalities, and 16.5% were SS-/C- without X-rays abnormalities. The positive rates for TB-SA antibody in the three groups were 57.6, 44.6 and 44.2%, respectively, before treatment, and 18.2, 19.1 and 26.9%, respectively, at E6MT. There was a significant decrease in TB-SA antibody positivity with treatment for all 3 groups. The TB-SA antibody test may be a useful adjunct to diagnose tuberculosis in SS- pulmonary TB patients, and may be useful for monitoring treatment outcomes of SS- pulmonary TB patients.