Early detection of perinatal tuberculosis using a whole blood interferon-gamma release assay

The diagnosis of perinatal tuberculosis (TB) is problematic because of its nonspecific presentation, the difficulty of obtaining microbiological confirmation, and the unreliability of the tuberculin skin test. Immunodiagnosis of TB has received new attention with the discovery of Mycobacterium tuberculosis-specific immunodominant antigens (early secreted antigenic target 6 [ESAT-6] and culture filtrate protein 10 [CFP-10]) that are encoded by the RD1 region of the pathogen. A whole blood assay has recently been developed to quantitatively measure interferon- gamma production by lymphocytes specific to these antigens, but its evaluation in the diagnosis of TB in infants and children has been limited to date.

In addition to routine diagnostic evaluation (tuberculin skin tests, culture of early-morning gastric aspirate samples, and chest radiographs), 2 infants with suspected perinatal TB were investigated with a whole blood interferon-gamma release assay.

The results of the tuberculin skin tests were negative for both patients. The findings of the chest radiographs were abnormal with features suggestive of miliary TB. A whole blood interferon- gamma release assay was performed and yielded positive results within 48 h after admission to the hospital for both patients, prompting early antituberculous treatment. M. tuberculosis was cultured after 6 weeks from gastric aspirate samples collected on admission to the hospital from both infants. At 6 months of age, both infants were thriving and had acheived normal developmental milestones.

The advent of interferon- gamma release assays may prove to be useful in the evaluation of infants with suspected perinatal TB.