Use of a T Cell Interferon-γ Release Assay to Evaluate Tuberculosis Risk in Newly Qualified Physicians in Singapore Healthcare Institutions

2009 ◽  
Vol 30 (9) ◽  
pp. 870-875 ◽  
Author(s):  
C. B. E. Chee ◽  
L. K. Y. Lim ◽  
T. M. Barkham ◽  
D. R. Koh ◽  
S. O. Lam ◽  
...  

Background.Surveillance for latent tuberculosis in high-risk groups such as healthcare workers is limited by the nonspecificity of the tuberculin skin test (TST) in BCG-vaccinated individuals. The Mycobacterium tuberculosis antigen-specific interferon-γ release assays (IGRAs) show promise for more accurate latent tuberculosis detection in such groups.Objective.To compare the utility of an IGRA, the T-SPOT.TB assay, with that of the TST in healthcare workers with a high rate of BCG vaccination.Methods.Two hundred seven medical students from 2 consecutive cohorts underwent the T-SPOT.TB test and the TST in their final year of study. Subjects with negative baseline test results underwent repeat testing after working for 1 year as junior physicians in Singapore's public hospitals.Results.The baseline TST result was an induration 10 mm or greater in diameter in 177 of the 205 students who returned to have their TST results evaluated (86.3%), while the baseline T-SPOT.TB assay result was positive in 9 (4.3%) of the students. Repeat T-SPOT.TB testing in 182 baseline-negative subjects showed conversion in 9 (4.9%). A repeat TST in 18 subjects with baseline-negative TST results did not reveal any TST result conversion.Conclusions.The high rate of positive baseline TST results in our BCG-vaccinated healthcare workers renders the TST unsuitable as a surveillance tool in this tuberculosis risk group. Use of an IGRA has enabled the detection and treatment of latent tuberculosis in this group. Our T-SPOT.TB conversion rate highlights the need for greater tuberculosis awareness and improved infection control practices in our healthcare institutions.

2008 ◽  
Vol 29 (9) ◽  
pp. 878-886 ◽  
Author(s):  
Nira R. Pollock ◽  
Antonio Campos-Neto ◽  
Suely Kashino ◽  
Danielle Napolitano ◽  
Samuel M. Behar ◽  
...  

Objective.In late 2006, our hospital implemented use of the QuantiFERON-TB Gold (QFT-G) assay, a whole-blood interferon-γ release assay, for detection of tuberculosis infection. All newly hired healthcare workers (HCWs) with positive Mantoux tuberculin skin test (TST) results were routinely tested with the QFT-G assay, to take advantage of its higher specificity. We then undertook a quality assurance review to evaluate the QFT-G test results in HCWs with multiple risk factors for latent tuberculosis infection (LTBI).Methods.The clinical records for TST-positive HCWs tested with the QFT-G assay were reviewed. HCWs with 2 or more risk factors commonly associated with LTBI were classified as “increased risk” (IR). IR HCWs who had negative QFT-G test results underwent repeat QFT-G testing and were offered testing with a different interferon-γ release assay (T-SPOT.TB) and with extended T cell stimulation assays.Results.Ofl43 TST-positive HCWs tested with the QFT-G assay, 26 (18%) had positive results, 115 (81%) had negative results, and 2 (1 %) had indeterminate results. Of 82 IR HCWs, 23 (28%) had positive QFT-G test results, and 57 (70%) had negative results. Of the 57 IR HCWs with negative results, 43 underwent repeat QFT-G testing: 41 had negative results again, and 2 had positive results. These 43 HCWs were also offered additional testing with the T-SPOT.TB diagnostic, and 36 consented: 31/36 tested negative, and 5/36 tested positive. Extended assays using the antigens ESAT-6 and CFP-10 confirmed the positive results detected by the overnight assays and yielded positive results for an additional 7/36 (19%) of individuals; strikingly, all 36 HCWs had strongly positive test results with assays using purified protein derivative.Conclusions.The extreme discordance between the results of our clinical diagnostic algorithm and the results of QFT-G testing raises concern about the sensitivity of the QFT-G assay for detection of LTBI in our HCWs. Results of extended stimulation assays suggest that many of our IR HCWs have indeed been sensitized to Mycobacterium tuberculosis. It is possible that the QFT-G assay identifies those at higher reactivation risk rather than all previously infected, but, in the absence of long-term follow-up data, we should interpret negative QFT-G results with some caution.


2010 ◽  
Vol 42 (11-12) ◽  
pp. 943-945 ◽  
Author(s):  
Hye Yun Park ◽  
Kyeongman Jeon ◽  
Gee Young Suh ◽  
O Jung Kwon ◽  
Doo Ryeon Chung ◽  
...  

2010 ◽  
Vol 16 (2) ◽  
pp. 211-221
Author(s):  
José Torres Costa ◽  
Rui Silva ◽  
Raul Sá ◽  
Maria João Cardoso ◽  
Carla Ribeiro ◽  
...  

2011 ◽  
Vol 96 (2) ◽  
pp. 284-288 ◽  
Author(s):  
Marcus Ang ◽  
Wong Wanling ◽  
Soon-Phaik Chee

2009 ◽  
Vol 13 (5) ◽  
pp. 280-282 ◽  
Author(s):  
Alfred Goodfellow ◽  
Douglas N. Keeling ◽  
Robert C. Hayes ◽  
Duncan Webster

Background: With increasing use of immunosuppressive therapy, including tumor necrosis factor a inhibitors, there is concern about infectious complications, including reactivation of latent Mycobacterium tuberculosis infection. Routine testing prior to administration of systemic immunosuppression includes the tuberculin skin test, which lacks sensitivity and specificity and may be difficult to interpret in the presence of extensive cutaneous disease. Treatment of individuals with latent tuberculosis infection is recommended when immunosuppressive medications are to be employed. Observations: We report a case in which a diagnosis of latent tuberculosis infection in a patient with extensive bullous pemphigoid was clarified by the use of an interferon-γ release assay after equivocal tuberculin skin test results. Conclusion: Interferon-γ release assays are useful adjuncts to the tuberculin skin test in the diagnosis of latent tuberculosis infection in the setting of extensive cutaneous disease.


2017 ◽  
Vol 49 (3) ◽  
pp. 1601546 ◽  
Author(s):  
David Z. Roth ◽  
Lisa A. Ronald ◽  
Daphne Ling ◽  
Leslie Y. Chiang ◽  
Victoria J. Cook ◽  
...  

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