Prospective evaluation of latent tuberculosis with interferon-gamma release assays in drug and alcohol abusers.
ABSTRACT In vitro tests have been developed for the diagnosis of tuberculosis (TB) infection. The objective was to analyse latent TB infection in drug and alcohol abusers through two interferon-gamma techniques. One hundred and thirty-nine patients were admitted between February 2006 and May 2007. Mean age was 39.8 years [31% HIV positive]. The enzyme immunoassay (EIA) and enzyme-linked immunospot (ELISPOT) interferon-gamma assays were positive in 34% of patients with an agreement of 83% (kappa=0.63). Tuberculin skin test (TST) was positive in 29% of patients and the agreement of TST with EIA and ELISPOT interferon-gamma assays was 85% (kappa=0.62) and 83% (kappa=0.57), respectively. Almost 50% of patients with history of TB had a positive in vitro test. In conclusion, we observed a high prevalence of latent TB and good agreement between the new in vitro tests that otherwise may continue to be positive long after developing TB disease.
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ABSTRACT: Background HIV infected children are at increased risk of TB disease and require annual TB screening. Data on use of IGRA for TB screening in them are limited. We retrospectively evaluated the usefulness of Quantiferon Gold-in-tube test (QFT), an IGRA in screening for LTBI in relatively healthy, immunologically stable HIV infected children. Methods HIV infected children with no prior history of TB were screened for latent TB as part of routine care. They underwent risk of TB assessment, TST and QFT. QFT was repeated twice or three times depending on the quantitative values. Independent test validation was also performed. Results Eighty one children had 109 QFT tests. All had adequate mitogen responses. The initial QFT was positive in 15 (18.5%) children; quantitative IGRA responses were 0.35-1.0 IU/mL in 9 (60%), 1.0-10 IU/mL in5 (33.3%) and >10 IU/mL in 1 (6.7%). None that tested positive had documented TB exposure or TB disease. Baseline characteristics in the QFT positive and negative groups were similar. Repeat testing within 17 weeks demonstrated reversion to negative in 79% of cases. Repeat blinded independent testing of all QFT positive results and a random selection of initial negative tests demonstrated concordance in 96% of cases. Seven children (QFT > 1.0 IU/mL or positive TST) were offered INH preventive therapy. In no case has TB disease developed in 2 years of close follow-up. Conclusions QFT is a valid method for LTBI screening relatively healthy, immunologically stable HIV infected children. However, reversion to negative on repeat testing and lack of correlation with TST results and risk of TB exposure makes interpretation difficult.BMC Infectious Diseases 09/2014; 14(1):516. DOI:10.1186/1471-2334-14-516 · 2.56 Impact Factor
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ABSTRACT: Two compulsory drug rehabilitation centres in Yunnan and Sichuan Provinces, Southwest China. To understand barriers to tuberculosis (TB) care among drug users in China, and to provide policy recommendations to improve TB control in the drug-using population. A qualitative study was designed using in-depth interviews with 147 drug users with TB and 12 key informants. Drug users were purposively selected from two compulsory drug rehabilitation centres and key informants from national and provincial justice administration, local TB control dispensaries and compulsory drug rehabilitation centres. Lack of health awareness and knowledge was reported as one barrier to TB care among drug users. The majority of the respondents lacked social support and perceived fear and stigma when seeking TB care. More than half of the respondents who had discontinued their anti-tuberculosis treatment reported that this was due to drug use. Limited provision of TB care in the compulsory drug rehabilitation centres and local TB control dispensaries was also reported as one of the barriers to TB care among drug users. These findings suggest that barriers to TB care for drug users are associated not only with the drug users themselves, but also with the providers and societal factors. Health professionals and policy makers should be aware of these barriers in China.The International Journal of Tuberculosis and Lung Disease 10/2013; 17(10):1358-63. DOI:10.5588/ijtld.12.0784 · 2.76 Impact Factor
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ABSTRACT: There is currently no 'gold standard' for diagnosis of latent tuberculosis infection (LTBI), and both the tuberculin skin test and interferon-gamma release assays (IGRAs) are used for diagnosis; the latter have a higher sensitivity than tuberculin skin test for diagnosis of LTBI in HIV-infected individuals with lower CD4 counts. No evidence-base exists for selection of IGRA methodology to identify LTBI among human immunodeficiency virus-infected patients in the UK. We prospectively evaluated two commercially available IGRA methods (QuantiFERON-TB Gold In Tube (QFG) and T-SPOT.TB) for testing LTBI among HIV-infected patients potentially nosocomially exposed to an HIV-infected patient with 'smear-positive' pulmonary tuberculosis. Among the exposed patients median CD4 count was 550 cells/µL; 105 (90%) of 117 were receiving antiretroviral therapy, of who 104 (99%) had an undetectable plasma HIV load. IGRAs were positive in 12 patients (10.3%); QFG positive in 11 (9.4%) and T-SPOT.TB positive in six (5.1%); both IGRAs were positive in five patients (4.3%). There was one indeterminate QFG and one borderline T-SPOT.TB result. Concordance between the two IGRAs was moderate (κ = 0.56, 95% confidence interval (CI) = 0.27-0.85). IGRAs were positive in only 4 (29%) of 14 patients with previous culture-proven tuberculosis. No patient developed tuberculosis during 20 months of follow-up.International Journal of STD & AIDS 07/2013; 24(10). DOI:10.1177/0956462413486459 · 1.04 Impact Factor