Comparison of serologic status of Toxoplasma gondii infection in pre- and post-heart transplantation in a pediatric population: A preliminary study.

Background: Toxoplasmosis is an important opportunistic infection in immunocompromised children, especially in heart transplant recipients. This study aimed to investigate pre- and post-transplant serology for toxoplasmosis along with post-transplant PCR in pediatric heart transplant patients.

Methods: This cross-sectional study was performed on 38 heart transplant recipients aged 1-17 years, by the end of 2018. Pre- and post-transplant IgM and IgG titrations were measured using ELISA method. Nested PCR of B1 gene was performed to identify Toxoplasma gondii (T gondii) infection after transplant.

Results: Totally, 11.4% of patients had positive IgG and 91.4% had negative IgM for toxoplasmosis before heart transplantation. The mean of pre-transplant IgG titration for seropositive and seronegative patients was 22.32 ± 15.30 IU/mL and 1.49 ± 1.15 IU/mL, respectively (P < .001). All cases were on chemoprophylaxis with trimethoprim-sulfamethoxazole (TMP/SMX). The mean of post-transplant IgG titration was 1.62 ± 1.87 IU/mL, which was negative for all cases. Investigating pre-transplant, IgM titration, 5.7% were positive, 91.4% were negative, and 2.9% were borderline. All cases were post-transplant IgM negative. The mean of post-transplant IgG titrations was significantly higher in the first 6 months (3.26 ± 2.68 IU/mL) compared to 6-12 (1.30 ± 1.34 IU/mL; P = .039) and > 12 months (1.07 ± 1.27 IU/mL; P = .004) time periods. The result of PCR for B1 gene in all cases was negative.

Conclusions: Chemoprophylaxis with TMP/SMX seems to be effective in prevention of T gondii infection or reactivation among pediatric heart transplantation population. Anti-T. gondii-IgG level alone may not be sensitive enough for evaluation of the infection at least after 6 months post-transplantation.