Quantitative Analysis of Gamma Interferon Release Assay Response in Children with Latent and Active Tuberculosis.

The use of interferon gamma (IFN-γ) release assays (IGRAs) for the diagnosis of tuberculosis (TB) infection in children is still under debate because of concerns about the immature immune response in children. The aim of this study was to investigate quantitative values of the QuantiFERON-TB Gold In-Tube (QFT-IT) test, a commercially available IGRA, in a large cohort of children screened for TB infection. A retrospective analysis was conducted on samples from 517 children aged 0 to 14 years old at the Pediatric Unit of S. Orsola-Malpighi University Hospital of Bologna (Italy); quantitative responses to QFT-IT stimuli were analyzed according to diagnosis and age. Elevated IFN-γ values in the QFT-IT nil (background) tube were statistically associated with diagnosis of active TB. Quantitative IFN-γ response to Mycobacterium tuberculosis-specific antigens (TB Ag) was not significantly different in children with active TB compared to those with latent TB infection (LTBI), even though the median values were higher in the first group. When children were grouped by age, those less than 5 years old produced significantly higher levels of IFN-γ in response to TB Ag if they had active TB (median 10 IU/ml) than those with LTBI (median 1.96 IU/ml). IFN-γ response to mitogen increased with age. The overall rate of indeterminate results was low (3.9%), and no indeterminate QFT-IT values were observed in active or latent TB patients. In conclusion, quantitative QFT-IT values could provide further information to clinicians to manage TB in children, and these observations could be transferred to the new version of the test, QuantiFERON-TB Gold Plus, which to date lacks data from the pediatric population.

Quantiferon-TB Gold In-Tube Improves Tuberculosis Diagnosis in Children.

BACKGROUND: The diagnostic accuracy of Quantiferon-TB Gold In-Tube (QFT-IT) is uncertain in the pediatric population, while tuberculin skin test (TST) is still conventionally used despite its limitations. The aim of this study was to compare the performance of QFT-IT with TST in a large cohort of children screened for tuberculosis (TB) infection because of contact tracing, suspected TB, arrival from endemic country or immunosuppressive therapy. METHODS: A retrospective analysis was conducted on 517 children 0-14 years of age evaluated at the pediatric unit of the S. Orsola-Malpighi University Hospital of Bologna, Italy; 366 of them were also tested with TST. Results were analyzed for Calmette-Guérin bacillus vaccination, country of origin, reason for testing, diagnosis and age. RESULTS: The overall agreement between the 2 tests was 89.9%, but it was highly affected by Calmette-Guérin bacillus vaccination (P < .0001). According to diagnosis and age, QFT-IT detected latent tuberculous infection cases better than TST in all age groups. Sensitivity for diagnosing active TB in symptomatic children was higher for QFT-IT than TST (93.3% vs. 86.5%), especially in children younger than 2 years, while specificity was high for both tests (99.3% and 98.8%, respectively). Low rate of indeterminate QFT-IT results (3.9%) was not differently distributed among age groups, but was associated with diagnosis of TB exclusion (P < 0.0001), mainly pneumonia (35%), and to Italian children (P = 0.0024). CONCLUSIONS: Despite the concern about the use of QFT-IT in children because of their immature immune system, our results suggest the preferential use of QFT-IT as a support tool for diagnosis and management of TB, even in infants.

Use of transrenal DNA for the diagnosis of extrapulmonary tuberculosis in children: a case of tubercular otitis media.

The diagnosis of tuberculosis (TB) is difficult in children, especially for smear-negative pulmonary and extrapulmonary TB, which are common at this age. We report an 11-year-old girl with TB otitis media with negative smear microscopy and Xpert MTB/RIF but positive Mycobacterium tuberculosis-specific transrenal DNA (Tr-MTB-DNA) test results and culture for M. tuberculosis.

Chronic eosinophilic pneumonia: a paediatric case.

Chronic eosinophilic pneumonia (CEP) is a rare disorder in children, characterised by respiratory and systemic symptoms, with a generally good prognosis. A 11-year-old asthmatic girl was admitted to our clinic with a 3-month history of progressive cough, dyspnoea, weight loss and asthenia. Peripheral blood eosinophilia, multiple bilateral pulmonary infiltrates to the x-ray, multiple nodules with a surrounding ground-glass halo and peripheral predominance to the chest CT suggested the diagnosis of eosinophilic lung disease (ELD). Further investigations ruled out other ELD and supported diagnosis of CEP. The response to oral corticosteroids was dramatic, no relapses were reported in 2-year follow-up while the patient was under inhaled corticosteroids for pre-existing asthma.