Background. T-SPOT.TB is an interferon gamma release assay for detecting Mycobacterium tuberculosis infection. The requirement\r\nto process within 8 hours is constraining, deters use, and leads to invalid results. Addition of T Cell Xtend reagent may allow\r\ndelayed processing, but has not been extensively field tested. Design. Consecutive AFB smear positive adult tuberculosis patients\r\nwere prospectively recruited in Dar es Salaam, Tanzania. Patients provided a medical history, 1ââ?¬â??3 sputum samples for culture\r\nand 1 blood sample which was transported to the laboratory under temperature-controlled conditions. After overnight storage,\r\n25 Ã?µL of T Cell Xtend reagent was added per mL of blood, and the sample was tested using T-SPOT.TB. Results. 143 patients\r\nwere enrolled: 57 patients were excluded because temperature control was not maintained, 19 patients were excluded due to red\r\nblood cell contamination, and one did not provide a sputum sample for culture. Among 66 evaluable patients, overall agreement\r\nbetween T-SPOT.TB and culture was 95.4% (95%CI; 87.1ââ?¬â??99.0%) with Kappa value 0.548. Sensitivity of T-SPOT.TB when using T\r\nCell Xtend reagent was 96.8% (95%CI; 88.8ââ?¬â??99.6%). Conclusions. When T Cell Xtend reagent is added to specimens held overnight\r\nat recommended temperatures, T-SPOT.TB is as sensitive as the standard assay in patients with tuberculosis.
Loading....