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Micro-Colony Forming Unit Assay for Efficacy Evaluation of Vaccines Against Tuberculosis
Published on: July 28, 2023
Evaluating the non-tuberculous mycobacteria effect in the tuberculosis infection diagnosis
I Latorre1, M De Souza-Galvão, J Ruiz-Manzano
1Servei de Microbiologia, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Carretera del Canyet s/n, 08916 Badalona Barcelona Spain.
Abstract:
The aim of the present study was to determine the role of previous non-tuberculous mycobacteria sensitisation in children as a factor of discordant results between tuberculin skin test (TST) and an in vitro T-cell based assay (T-SPOT.TB; Oxford Immunotec, Oxford, UK). We enrolled 21 non-bacille Calmette-Guérin-vaccinated paediatric patients for suspicious of latent tuberculosis infection (LTBI). These patients yielded a positive TST and a negative T-SPOT.TB. Cells were stimulated with Mycobacterium avium sensitin (having cross-reaction with Mycobacterium intracellulare and Mycobacterium scrofulaceum) and the presence of reactive T-cells was determined by an ex vivo ELISPOT. From the 21 patients, in 10 cases (47.6%), we obtained a positive ELISPOT result after stimulation with M. avium sensitin, in six (28.6%) cases, the result was negative and in the remaining five (23.8%) cases, the result was indeterminate. In conclusion, previous non-tuberculous mycobacteria sensitisation induces false-positive results in the TST for diagnosing LTBI and the use of gamma-interferon tests could avoid unnecessary chemoprophylaxis treatment among a child population.
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