Abstract
Background: Tuberculosis is one of the serious occupational diseases among health care workers, especially those who work with patients suffering from respiratory disorders. It is important to assess latent tuberculosis infection status in such workers using interferon- release assays, including QuantiFERON-TB Gold and its successor, the QuantiFERON-TB Gold in-Tube test. Although the relative efficacies of these two methods have been evaluated in patients with tuberculosis, data from health care workers in Japan have not been extensively examined. Purpose: In the present study, we examined the utilities of the QuantiFERON-TB Gold and QuantiFERON-TB Gold in-Tube tests to detect latent tuberculosis infections in staff working in a respiratory disease hospital in Japan. We also longitudinally compared data from these subjects obtained using the QuantiFERON-TB Gold assay. Methods: We collected blood samples from 120 staff members and performed both the QuantiFERON-TB Gold and QuantiFERON-TB Gold in-Tube assays. A total of 58 subjects had previously been tested 5 years prior using the QuantiFERON-TB Gold assay, and we compared these data with our more recent information. Results: The QuantiFERON-TB Gold in-Tube test tended to yield higher test values than did the QuantiFERONTB Gold test, suggesting that the former test may be more sensitive when used to detect latent tuberculosis infection. In both tests, the results differed in 32 instances (26.7%), associated with significant difference (p<0.001, =0.55). In 94 subjects with negative QuantiFERON-TB Gold test results, 16 (17.0%) were intermediate and 11 (11.7%) positive by QuantiFERON-TB Gold in-Tube test. The longitudinal comparison confirmed this suggestion. The number of subjects rated “intermediate” in terms of tuberculosis status differed, with statistical significance, when the two datasets were compared. Conclusion: Health care workers should be screened for possible tuberculosis infections using the QuantiFERON-TB Gold in-Tube test, which is more sensitive than the QuantiFERON-TB Gold test.
Highlights
The incidence of tuberculosis (TB) in Japan is less than 20 per 100,000 population and is continuing to decline
Health care workers should be screened for possible tuberculosis infections using the QuantiFERON-TB Gold in-Tube test, which is more sensitive than the QuantiFERON-TB Gold test
When comparing QuantiFERON-TB Gold (QFT-G) and QuantiFERONTB Gold in-Tube test (QFT-GIT) assay data from 120 blood samples obtained at the same time, QFT-GIT yielded higher IFN-γ levels than did QFT-G in most samples (Figure 1)
Summary
The incidence of tuberculosis (TB) in Japan is less than 20 per 100,000 population and is continuing to decline. Evaluation of Mycobacterium tuberculosis (Mtb) infective status is crucial in HCW working in hospitals dedicated to TB patients [2,7,8] In such contexts, screening of HCW should be routine and data should be evaluated longitudinally [2,9]. Tuberculosis is one of the serious occupational diseases among health care workers, especially those who work with patients suffering from respiratory disorders. The relative efficacies of these two methods have been evaluated in patients with tuberculosis, data from health care workers in Japan have not been extensively examined. Purpose: In the present study, we examined the utilities of the QuantiFERON-TB Gold and QuantiFERON-TB Gold in-Tube tests to detect latent tuberculosis infections in staff working in a respiratory disease hospital in Japan. We longitudinally compared data from these subjects obtained using the QuantiFERON-TB Gold assay
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