Background: Candida infections pose a significant threat to pediatric transplant recipients, necessitating a comprehensive analysis of the species involved and their susceptibility to antifungal agents. So, this study aims to investigate the species distribution of Candida isolates and assess their antifungal susceptibility profiles in pediatric transplant recipients in a main transplant center in Iran.
Methods: In the current study, all patients ≤ 18 years old who underwent liver/kidney transplant surgery between September 2021 and 2022 were included. The patient’s demographic, clinical, and mycological information were collected. The DNA-sequencing method was used to accurately identify the species of the isolates. Antifungal susceptibility testing for antifungal agents
(fluconazole, itraconazole, voriconazole, caspofungin, and amphotericin B) was performed using the broth microdilution method according to The CLSI guidelines.
Results: From September 2021 to 2022, 117 pediatric transplantation including 89 liver transplantation and 28 kidney transplantation was performed. The predominant comorbidity in pediatric liver recipients was neurologic disorders (27/89:30.3%), while in kidney was hypertension (22/28:78.6 %). Candidemia was diagnosed in 5/89 (5.6%) of liver and 1/28 (3.6%) of kidney transplant recipients. Moreover, Candida peritonitis was detected in two liver recipients and one kidney recipient. Respiratory/urinary tract colonization of Candida species was observed in 6/89 of liver and 3/28 of kidney recipients. The most frequent species isolated from the patients was C. albicans (12/16: 75%). In addition to the P. kudriavzevii species with inherent resistance to fluconazole, one of C. albicans isolates and one C. tropicalis isolate were also identified as fluconazole-resistant (3/29:10.3%) (table 1 ). All Candida spp. were classified as susceptible for caspofungin, and also were wild-type (WT) for amphotericin B. Among C.albicans isolates, a high proportion of non-wild-type (NWT) phenotypes were found for voriconazole. With no post-operative deaths among kidney transplant recipients during hospitalization, the in-hospital mortality rate in liver transplant recipients was 13.5 %. The rejection rate was 3.5 % and 7.9 % in kidney and liver transplant recipients, respectively.

Conclusion: Current study highlights the need to monitor species distribution and antifungal resistance in pediatric populations undergoing transplantation. Although the rates of post-transplant Candida infections and antifungal resistance are low in our center, adapting treatment protocols to evolving resistance patterns can assist healthcare providers in combating Candida infections in pediatric transplant recipients.