Discordant QuantiFERON-TB Gold Test Results Among US Healthcare Workers With Increased Risk of Latent Tuberculosis Infection: A Problem or Solution?

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.

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Rate of Latent Tuberculosis Infection Detected by Occupational Health Screening of Nurses New to a London Teaching Hospital

Infection Control and Hospital Epidemiology ◽

10.1086/597546 ◽

2009 ◽

Vol 30 (6) ◽

pp. 581-584 ◽

Cited By ~ 13

Author(s):

Priya Khanna ◽

Vladyslav Nikolayevskyy ◽

Fiona Warburton ◽

Elek Dobson ◽

Francis Drobniewski

Keyword(s):

Tuberculin Skin Test ◽

Skin Test ◽

Latent Tuberculosis Infection ◽

Latent Tuberculosis ◽

Interferon Γ ◽

Tuberculosis Infection ◽

Release Assay ◽

Ifn Γ ◽

Positive Results ◽

Tuberculosis Prevalence

The prevalence of latent tuberculosis infection in a cohort of nurses new to a London hospital was 7.6% (13 of 171), using an interferon-γ(IFN-γ) release assay, and 16.2% (24 of 148), using the tuberculin skin test. On multivariate analysis, birth in a country with tuberculosis prevalence of more than 40 cases per 100,000 population was associated with positive results of both the IFN-γ release assay and the tuberculin skin test.

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754. Prevalence of Latent Tuberculosis Infection Among Healthcare Workers at a Tertiary Care University Hospital

Open Forum Infectious Diseases ◽

10.1093/ofid/ofy210.761 ◽

2018 ◽

Vol 5 (suppl_1) ◽

pp. S271-S271

Author(s):

Eun Ju Choo ◽

Se Yoon Park

Keyword(s):

Risk Factors ◽

Healthcare Workers ◽

Latent Tuberculosis Infection ◽

Tertiary Care ◽

Latent Tuberculosis ◽

Tuberculosis Infection ◽

University Hospital ◽

Increased Risk ◽

High Prevalence ◽

Univariate Analyses

Abstract Background We investigated the prevalence of latent tuberculosis infection (LTBI) among healthcare workers (HCWs) and analyzed its risk factors in a tertiary care university hospital in South Korea in a population with intermediate tuberculosis (TB) burden. Methods A standard questionnaire regarding the baseline demographics and risk factors for LTBI was given to each participant. QuantiFERON-TB GOLD In-Tube (QFT-GIT) assay and chest radiography were performed to investigate the rate of LTBI. Results A total of 1,429 participants, 213 (14.9%) doctors and 988 (69.1%) nurses and 228 (16.0%) others were enrolled. The mean age of the subjects was 33.0 years old, and 1,175 (82.2%) were female. Of the participants, 94.5% had received BCG vaccine. QFT-GIT assays were positive for 156 subjects (10.9%). Of the 213 doctors, 28 (13.1%) were positive by QFT-GIT, and among the 988 nurses, 94 (9.5%) had positive QFT-GIT results. Experience of working in hospital was significantly associated with positive LTBI test results by QFT-GIT assay. Gender and duration of employment as an HCW were significantly associated with having a positive QFT-GIT result in univariate analyses. In multivariate analyses, duration of employment as an HCW (>15 years) (odds ratio, 1.98; 95% confidence interval, 1.14–3.43) was independently associated with increased risk of a positive QFT-GIT result. Conclusion A high prevalence of LTBI was found among our HCWs. Considering the association between the experience of working in hospital and high risk of LTBI. The risk for tuberculosis infection among HCWs was higher than general population, which suggests that stricter preventive strategies against nosocomial tuberculosis infection should be implemented. Disclosures All authors: No reported disclosures.

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Prevalence of latent tuberculosis infection in BCG-vaccinated healthcare workers by using an interferon-gamma release assay and the tuberculin skin test in an intermediate tuberculosis burden country

Journal of Microbiology Immunology and Infection ◽

10.1016/j.jmii.2013.07.008 ◽

2015 ◽

Vol 48 (2) ◽

pp. 147-152 ◽

Cited By ~ 13

Author(s):

Wan-Ting Hung ◽

Susan Shin-Jung Lee ◽

Cheng-Len Sy ◽

Kuang-Sheng Wu ◽

Jui-Kuang Chen ◽

...

Keyword(s):

Tuberculin Skin Test ◽

Skin Test ◽

Interferon Gamma ◽

Healthcare Workers ◽

Latent Tuberculosis Infection ◽

Latent Tuberculosis ◽

Tuberculosis Infection ◽

Interferon Gamma Release Assay ◽

Release Assay

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Utility of an Interferon-γ Release Assay for Latent Tuberculosis Diagnosis in a Case of Bullous Pemphigoid

Journal of Cutaneous Medicine and Surgery ◽

10.2310/7750.2009.08062 ◽

2009 ◽

Vol 13 (5) ◽

pp. 280-282 ◽

Cited By ~ 1

Author(s):

Alfred Goodfellow ◽

Douglas N. Keeling ◽

Robert C. Hayes ◽

Duncan Webster

Keyword(s):

Tuberculin Skin Test ◽

Bullous Pemphigoid ◽

Skin Test ◽

Latent Tuberculosis Infection ◽

Latent Tuberculosis ◽

Interferon Γ ◽

Tuberculosis Infection ◽

Mycobacterium Tuberculosis Infection ◽

Cutaneous Disease ◽

Release Assay

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.

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