Background: Whole blood interferon-gamma assay QuantiFERON-TB2G (QFT-2G), which is a new specific method for diagnosing tuberculosis (TB), has been developed and used in the clinical field. The aim of the present study was to assess the usefulness of QFT-2G as an indicator, both for diagnosing childhood TB and for assessing therapeutic effectiveness.
Methods: The subjects were 61 children introduced to the TB outpatient department for the first time between June 2004 and March 2006. QFT-2G, the tuberculin test and chest computed tomography (CT) were performed for all patients.
Results: Ten patients having typical characteristics of primary tuberculosis (PTB) on chest CT, and diagnosed as having tubercle bacillus infections, all had positive reaction on QFT-2G. Of seven patients who had no abnormalities on diagnostic imaging but who reacted positively on QFT-2G, one developed TB later, and no TB was detected over the period of observation in 44 patients with negative QFT-2G at their first consultation. Moreover, four patients with non-tuberculous acid-fast bacilli in which Mycobacterium avium or Mycobacterium gordonae was detected had negative reaction on QFT-2G. In addition, all 10 patients with positive reactions on QFT-2G in whom the subsequent course of the disease was observed had decrease on QFT after treatment.
Conclusions: QFT-2G is a powerful tool with a wide application both in diagnosis and in assessment of treatment effectiveness in PTB.