Role of interferon-gamma release assay for screening and monitoring of latent tuberculosis infection in kidney transplant recipients

The reactivation of tuberculosis (TB) among kidney transplant (KT) recipients in an endemic area is of general concern. However, the epidemiology of latent TB infection (LTBI) status and its dynamic change responses have not been explored.

Between September 2020 and August 2021, a prospective study was conducted to investigate the status of LTBI in KT recipients who received a 9-month isoniazid universal prophylaxis. This status was measured using the interferon-gamma release assay (IGRA) with T-SPOT.TB before transplant, as well as at one month and nine months post-transplant.

Ninety-one KT recipients had a mean (SD) age of 45 (11) years, and 41% were female. Sixty-eight (75%) patients received a deceased donor allograft, and eighty-six (91%) patients received induction immunosuppressive therapy. The IGRA results were positive, borderline, negative, and indeterminate in 14 (15.4%), 6 (6.6%), 64 (70.3%), and 7 (7.8%) patients, respectively. Among 84 evaluable patients, 20 (23.8%) KT recipients were defined as having LTBI. Older age was significantly associated with LTBI (OR 1.06 [95% CI 1.01–1.12], p = 0.03). Among the 77 KT recipients who completed monitoring, 55 had negative IGRA results. Three (5.4%) KT recipients had conversion post-transplant. One of them developed pulmonary TB at 1 week after the transplant. Among the 13 patients with positive results, 8 (61.5%) remained positive, 1 (7.7%) had an indeterminate result at 1-month post-transplant and subsequently tested positive at 9 months post-transplant, and 4 (30.8%) experienced reversion to negative results throughout the study.

In a high TB-endemic area, one-quarter of KT recipients were reported to have LTBI, and the dynamic change of IGRA response in KT recipients is plausible post-transplant.