Diagnostic value of ELISPOT technique for osteoarticular tuberculosis.

ABSTRACT

BACKGROUND: Osteoarticular tuberculosis (TB) is a common severe form of extrapulmonary tuberculosis. Early di- agnosis and treatment can decrease the deformity of spine and limbs and joint dysfunction. METHODS: We compared and evaluated two commercially available rapid test kits based on the ELISPOT assay for the diagnosis of osteoarticular disease. RESULTS: The diagnostic sensitivity and specificity of the FS-SPOT assay (50.0% and 85.7%) were similar to those of the T-SPOT-TB assay (45.5% and 81.0%). When the two test wells in the T-SPOT-TB assay were both positive, the test wells in FS-SPOT assay were usually positive with the number of SFCs exceeding those in the negative control wells by more than 30. The sensitivities, specificities, PPV, NPV, and agreement of FS-SPOT assay results in 99 TB cases and 54 non-TB disease cases were 55.6%, 83.3%, 84.7%, 52.9%, and 66.0%, respectively. SFC counts from test wells in the TB group were significantly higher than those from the non-TB group (p < 0.001). CONCLUSIONS: Higher numbers of SFCs in the ELISPOT assay suggest higher risk of active TB. ELISPOT may be a diagnostic aide for active osteoarticular TB.