ABSTRACT
Objective To evaluate the diagnosis values of whole blood IFN-γ release assay on pulmonary tuberculosis ( TB)and extra-pulmonary tuberculosis. Methods One hundred and eighty five patients with tuberculosis( including 119 pulmonary TB and 66 extra-pulmonary TB),139 patients with other respiratory diseases and 100 healthy people were enrolled. Mycobacterium tuberculosis infection testing was conducted with methods of IFN -γ release assay,sputum bacterial culture and sputum smear,respectively. Results of pathogen culture and/or clinical diagnosis were used as the golden standard to evaluate the sensitivity and specificity of these three methods. Results Compared with the results of clinical diagnosis,the sensitivity and specificity of IFN-γ release assays was 93. 51% and 84. 52%,respectively. There was no significant difference in sensitivity between pulmonary diagnosis( 90. 76%) and extra - pulmonary diagnosis (98. 49%)(P>0. 05). The sensitivity of sputum smear was 11. 76% in patients with pulmonary and 3. 03% in patients with extra - pulmonary. And the sensitivity of sputum bacterial culture in these two patient groups was 24. 37% and 3. 03%,respectively. Sensitivity of the IFN-γ release assay was higher than that of sputum culture and sputum smear (P<0. 05). The results of pathogen culture showed that 33 of 424 samples were positive,in which 2 were mycobacterium abscessus positive and 31 were mycobacterium tuberculosis positive. Compared with the results of pathogen culture,the sensitivity of IFN-γrelease assay was 90. 32%(95%CI:75. 10% -96. 65%). Conclusion IFN-γrelease assay is a fast,sensitive and convenient method to detect pulmonary and extra pulmonary tuberculosis. It is worthy to be applied to clinical practice.
ABSTRACT
Objective To assess the validity of a newly developed in-house ELISPOT IFN-γ release assay (IGRA) for the detection of latent tuberculosis infection among HIV infected individuals. Methods In-house ELISPOT assay were performed, together with a tuberculin skin test in 205 health controls and 110 HIV infected individuals , who had no signs of active tuberculosis at time of enrolment . Results Using the ELISPOT assay, positivity rates for the 205 health controls, 110 HIV infected individuals and 47 AIDS patients on highly active antiretrovial therapy (HAART) were 7. 3% , 24.5% , 29. 8% , respectively. These results indicated that the positive rates obtained from HIV infected individuals (include patient on HAART) was significantly higher than health controls( P ＜ 0.001). We found no significant correlation between the CD4 cell count and positivity of ELISPOT assay (P ＞0.05 ). The proportion of subjects with a positive response to ELISPOT assay were higher than the proportion of tuberculin skin test(TST) responders(P＜0.0001) in HIV infected individuals. Conclusion Our study indicates that IGRA using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals.