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Mycobacterium tuberculosis infection in young children: analyzing the performance of the diagnostic tests
Tomàs M Pérez-Porcuna1, Carlos Ascaso2, Adriana Malheiro3
1Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil; Departament de Salut Pública, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalunya, Spain; Servei de Pediatria, CAP Valldoreix, Unitat de Investigació Fundació Mútua Terrassa, Hospital Universitari Mútua Terrassa, Terrassa, Catalunya, Spain.
Insights
Tuberculin Skin Test (TST) and Quantiferon-TB Gold (QFT) showed fair agreement in children exposed to tuberculosis. Factors like helminths, ferritin levels, and exposure time influenced discordant results, suggesting QFT may detect early infection.
Area of Science:
- Pediatrics
- Infectious Diseases
- Immunology
Background:
- Tuberculosis (TB) diagnosis in young children relies on tests like TST and QFT.
- Understanding factors affecting these tests is crucial for accurate diagnosis in pediatric populations.
Purpose of the Study:
- To evaluate the performance of TST and QFT in children aged 0-6 years with recent TB exposure.
- To identify factors that may modify TST and QFT results in this age group.
Main Methods:
- A cross-sectional study was conducted with 135 children in Manaus, Brazil.
- Both TST and QFT were administered and results analyzed against child characteristics and exposure details.
Main Results:
- TST positivity was 34.8% and QFT was 26.7%, with 14.1% indeterminate QFT results.
- Concordance between TST and QFT was fair (Kappa = 0.35).
- Both tests correlated with exposure intensity; TST also correlated with exposure duration. Intestinal helminths and ferritin levels were associated with discordant results.
Conclusions:
- TST and QFT showed lower than expected concordance in young children exposed to TB.
- Intestinal helminths, ferritin levels, and exposure time were linked to discordant results.
- Findings suggest QFT may be faster in detecting early TB infection, with ferritin as a potential biomarker.
Objective:
This study evaluated the performance of the Tuberculin Skin Test (TST) and Quantiferon-TB Gold in-Tube (QFT) and the possible association of factors which may modify their results in young children (0-6 years) with recent contact with an index tuberculosis case.
Materials And Methods:
A cross-sectional study including 135 children was conducted in Manaus, Amazonas-Brazil. The TST and QFT were performed and the tests results were analyzed in relation to the personal characteristics of the children studied and their relationship with the index case.
Results:
The rates of positivity were 34.8% (TST) and 26.7% (QFT), with 14.1% of indeterminations by the QFT. Concordance between tests was fair (Kappa = 0.35 P<0.001). Both the TST and QFT were associated with the intensity of exposure (Linear OR = 1.286, P = 0.005; Linear OR = 1.161, P = 0.035 respectively) with only the TST being associated with the time of exposure (Linear OR = 1.149, P = 0.009). The presence of intestinal helminths in the TST+ group was associated with negative QFT results (OR = 0.064, P = 0.049). In the TST- group lower levels of ferritin were associated with QFT+ results (Linear OR = 0.956, P = 0.036).
Conclusions:
Concordance between the TST and QFT was lower than expected. The factors associated with the discordant results were intestinal helminths, ferritin levels and exposure time to the index tuberculosis case. In TST+ group, helminths were associated with negative QFT results suggesting impaired cell-mediated immunity. The TST-&QFT+ group had a shorter exposure time and lower ferritin levels, suggesting that QFT is faster and ferritin may be a potential biomarker of early stages of tuberculosis infection.
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