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Open Access Highly Accessed Research article

Latent and subclinical tuberculosis in HIV infected patients: a cross-sectional study

Meaghan M Kall14*, Katherine M Coyne1, Nigel J Garrett1, Aileen E Boyd3, Anthony T Ashcroft2, Iain Reeves1, Jane Anderson1 and Graham H Bothamley3

Author Affiliations

1 Department of Sexual Health, Homerton University Hospital, Homerton Row, London, E9 6SR, United Kingdom

2 Department of Microbiology, Homerton University Hospital, Homerton Row, London, E9 6SR, United Kingdom

3 Department of Respiratory Medicine, Homerton University Hospital, Homerton Row, London, E9 6SR, United Kingdom

4 HIV and STI Department, Health Protection Services - Colindale, Health Protection Agency, 61 Colindale Avenue, London, NW9 5EQ, United Kingdom

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BMC Infectious Diseases 2012, 12:107  doi:10.1186/1471-2334-12-107

Published: 4 May 2012

Abstract

Background

HIV and tuberculosis (TB) are commonly associated. Identifying latent and asymptomatic tuberculosis infection in HIV-positive patients is important in preventing death and morbidity associated with active TB.

Methods

Cross-sectional study of one time use of an interferon-gamma release assay (T-SPOT.TB - immunospot) to detect tuberculosis infection in patients in a UK inner city HIV clinic with a large sub-Saharan population.

Results

542 patient samples from 520 patients who disclosed their symptoms of TB were tested. Median follow-up was 35 months (range 27-69). More than half (55%) originated from countries with medium or high tuberculosis burden and 57% were women. Antiretroviral therapy was used by 67%; median CD4 count at test was 458 cells/μl. A negative test was found in 452 samples and an indeterminate results in 40 (7.4%) but neither were associated with a low CD4 count. A positive test was found in 10% (50/502) individuals. All patients with positive tests were referred to the TB specialist, 47 (94%) had a chest radiograph and 46 (92%) attended the TB clinic. Two had culture-positive TB and a third individual with features of active TB was treated. 40 started and 38 completed preventive treatment. One patient who completed preventive treatment with isoniazid monotherapy subsequently developed isoniazid-resistant pulmonary tuberculosis. No patient with a negative test has developed TB.

Conclusions

We found an overall prevalence of latent TB infection of 10% through screening for TB in those with HIV infection and without symptoms, and a further 1% with active disease, a yield greater than typically found in contact tracing. Acceptability of preventive treatment was high with 85% of those with latent TB infection eventually completing their TB chemotherapy regimens. IGRA-based TB screening among HIV-infected individuals was feasible in the clinical setting and assisted with appropriate management (including preventive treatment and therapy for active disease). Follow-up of TB incidence in this group is needed to assess the long-term effects of preventive treatment.