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Role of Interferon Gamma Release Assay in Active TB Diagnosis among HIV Infected Individuals

Kabeen, B S A and Sikhamani, R and Swaminathan, Soumya and Perumal, Venkatesan and Paramasivan, Paulkumaran and Raja, Alamelu (2009) Role of Interferon Gamma Release Assay in Active TB Diagnosis among HIV Infected Individuals. PLoS ONE, 4 (5). pp. 1-7. ISSN 1932-6203

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immunodeficiency virus (HIV) infected individuals. In this study, we assessed the sensitivity of Interferon gamma release assay (IGRA) in active tuberculosis patients who were positive for HIV infection and compared it with that of tuberculin skin test (TST). Methodology/Principal Findings: A total of 105 HIV-TB patients who were naı¨ve for anti tuberculosis and anti retroviral therapy were included for this study out of which 53 (50%) were culture positive. Of 105 tested, QuantiFERON-TB Gold intube (QFT-G) was positive in 65% (95% CI: 56% to 74%), negative in 18% (95% CI: 11% to 25%) and indeterminate in 17% (95% CI: 10% to 24%) of patients. The sensitivity of QFT-G remained similar in pulmonary TB and extra-pulmonary TB patients. The QFT-G positivity was not affected by low CD4 count, but it often gave indeterminate results especially in individuals with CD4 count ,200 cells/ml. All of the QFT-G indeterminate patients whose sputum culture were positive, showed #0.25 IU/ml of IFN-c response to phytohemagglutinin (PHA). TST was performed in all the 105 patients and yielded the sensitivity of 31% (95% CI: 40% to 22%). All the TST positives were QFT-G positives. The sensitivity of TST was decreased, when CD4 cell counts declined. Conclusions/Significance: Our study shows neither QFT-G alone or in combination with TST can be used to exclude the suspicion of active TB disease. However, unlike TST, QFT-G yielded fewer false negative results even in individuals with low CD4 count. The low PHA cut-off point for indeterminate results suggested in this study (#0.25 IU/ml) may improve the proportion of valid QFT-G results.

Item Type: Article
Uncontrolled Keywords: Interferon, tuberculosis, HIV
Subjects: Tuberculosis > Laboratory Research > Immunological
Divisions: Basic Science Research > Immunology
Depositing User: Dr. Rathinasabapati R
Date Deposited: 11 Aug 2017 11:00
Last Modified: 02 Mar 2021 06:00

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