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PLoS One. 2012;7(6):e39838. doi: 10.1371/journal.pone.0039838. Epub 2012 Jun 26.

Bronchoalveolar lavage enzyme-linked immunospot for diagnosis of smear-negative tuberculosis in HIV-infected patients.

Author information

1
Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, California, United States of America. acattamanchi@medsfgh.ucsf.edu

Abstract

BACKGROUND:

Peripheral blood interferon-gamma release assays (IGRAs) have sub-optimal sensitivity and specificity for diagnosis of active pulmonary tuberculosis (TB). However, assessment of local immune responses has been reported to improve the accuracy of TB diagnosis.

METHODS:

We enrolled HIV-infected adults with cough ≥2 weeks' duration admitted to Mulago Hospital in Kampala, Uganda and referred for bronchoscopy following two negative sputum acid-fast bacillus smears. We performed an ELISPOT-based IGRA (T-SPOT.TB®, Oxford Immunotec, Oxford, UK) using peripheral blood and bronchoalveolar lavage (BAL) fluid mononuclear cells, and determined the accuracy of IGRAs using mycobacterial culture results as a reference standard.

RESULTS:

94 HIV-infected patients with paired peripheral blood and BAL IGRA results were included. The study population was young (median age 34 years [IQR 28-40 years]) and had advanced HIV/AIDS (median CD4+ T-lymphocyte count 60 cells/µl [IQR 22-200 cells/µl]). The proportion of indeterminate IGRA results was higher in BAL fluid than in peripheral blood specimens (34% vs. 14%, difference 20%, 95% CI 7-33%, p = 0.002). BAL IGRA had moderate sensitivity (73%, 95% CI 50-89%) but poor specificity (48%, 95% CI 32-64%) for TB diagnosis. Sensitivity was similar (75%, 95% CI 57-89%) and specificity was higher (78%, 95% CI 63-88%) when IGRA was performed on peripheral blood.

CONCLUSIONS:

BAL IGRA performed poorly for the diagnosis of smear-negative TB in a high HIV/TB burden setting. Further studies are needed to examine reasons for the large proportion of indeterminate results and low specificity of BAL IGRA for active TB in high HIV/TB burden settings.

PMID:
22745833
PMCID:
PMC3383728
DOI:
10.1371/journal.pone.0039838
[Indexed for MEDLINE]
Free PMC Article
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