Role of QuantiFERON-TB-Gold In Tube assay for active and latent tuberculosis infection in investigation of tuberculosis outbreak in a university.

BACKGROUND

Identification and monitoring of active tuberculosis (TB) and latent tuberculosis infection (LTBI) are the key steps to prevent transmission during a TB outbreak. The aim of this study was to evaluate the role of QuantiFERON-TB-Gold In Tube assay (QFT-GIT) in the investigation of active TB and LTBI cases during a TB outbreak in a university.

METHODS

In this study, enrolled students and teachers were evaluated with chest radiograph, questionnaire, and QFT-GIT test. The diagnosis of active pulmonary TB was based on sputum studies and chest radiographs. The questionnaire, which covered demographic information, underlying diseases, and environmental exposures, was applied to assess the association of risk factors by multiple logistic regressions.

RESULTS

A total of 159 participants completed the study protocol. Positive QFT-GIT results were demonstrated in class A (75.7%; 25/33), class B (57.1%; 20/35), and class C (37.5%; 3/8) in institute 1; class D (17.3%; 8/46) in institute 2; and class E (3.1%; 1/32) in institute 3; but none among the (0/5) administrative officers, who comprised the control group. "Number of contact with active TB cases" was strongly associated and correlated with the prediction of a positive QFT-GIT result in multivariate analysis (odds ratio = 1.99; 95% confidence interval, 1.52-2.61; p < 0.0001). Seven cases progressed to active TB infection, all showing positive QFT-GIT results (100%; 7/7).

CONCLUSION

Inclusion of QFT-GIT may be helpful in controlling and monitoring of active TB and LTBI cases during an investigation of a TB outbreak. The finding demonstrated that the QFT-GIT test was useful in accurately identifying infected and uninfected students, permitting rapid intervention.