Interferon Gamma Release Assay in a 12-month-old BCG-Vaccinated Infant with Latent Tuberculosis Infection and Isolated Mycobacterium fortuitum

The aim is to present a case of serial use of interferon-y release assay (IGRA) test in the evaluation of an infant with a latent tuberculosis infection (LTBI) accompanied with a positive finding of Mycobacterium (M.) fortuitum in gastric juice. In addition to routine diagnostic evaluation (tuberculin skin test (1ST), culture of gastric juice, chest X-rays), a 12-month-old female infant with a history of close family contact and a case of active tuberculosis was investigated with IGRA (QuantiFERON-TB Gold In-Tube, Cellestis, Carnegie, Australia). Tuberculin skin tests were positive. The first result of IGRA (on admission) was negative; the second (day 16) and third (day 57) results of IGRA were positive. M. fortuitum was cultured from gastric juice samples. Positive IGRA finding confirmed LTBI, and prophylaxis with isoniazid was administered. Since M. fortuitum does not express antigens that could be confirmed by the QuantiFERON-TB Gold In-Tube test, isolation of M. fortuitum could be interpreted as a possible contamination. [PUBLICATION ABSTRACT]