Microsporidiosis is increasingly being recognized as an emerging pathogen in solid organ transplantation with the potential for significant morbidity and mortality. There have been very few cases reported in the pediatric solid organ transplant population. We report on a 4-year-old male kidney transplant recipient determined to have donor-derived microsporidiosis (Encephalitozoon cuniculi) approximately 12 weeks status post deceased donor kidney transplantation.

The recipient has a history of congenital nephrotic syndrome and received his first kidney transplant a few weeks prior to his 4th birthday. The cause of death for the young adult donor, with no significant past medical history, was pedestrian vs automobile accident. The recipient received basiliximab and solumedrol for induction followed by tacrolimus, prednisone, and mycophenolate mofetil for maintenance immunosuppression. The patient had prolonged hospitalization post-transplant due to diarrhea and feeding intolerance. In the months following transplantation, he continued to have symptomatic diarrhea and persistently rising creatinine.

Approximately 12 weeks status post transplantation, our team was alerted by the organ procurement organization (OPO) that two other patients who had received organs from same donor had posttransplant infections with Encephalitozoon cuniculi. Both tested positive for Encephalitozoon cuniculi with plasma metagenomic next-generation sequencing (mNGS). The heart transplant recipient had symptomatic diarrhea and the liver transplant recipient had fever of unknown origin.

We immediately consulted with infectious diseases, started preemptive albendazole, and sent mNGS, urine microsporidia PCR, urine cytology, and stool microsporidia. mNGS was the only study that returned low-level positive for Encephalitozoon cuniculi. The patient completed a 6-week course of albendazole with no reported side effects. Continued monitoring has showed no recurrence on three subsequent mNGS over the following 4 months. The patient’s creatinine slowly down trended and his diarrhea became less symptomatic, which may be attributable, in part, to the treatment of the microsporidiosis. He has not had a kidney transplant biopsy to date.

Strong communication with our local OPO and transplant teams led to the recognition of Encephalitozoon cuniculi in our pediatric patient prior to the development of fulminant disease. To date, our patient has had no evidence of recurrent microspordiosis.

There is a wide spectrum of presentation of microsporidiosis in solid organ transplant patients and it may be an underrecognized cause of morbidity and mortality. Clinicians need to have a high index of suspicion for donor-derived infections, including microsporidiosis, in patients with persistently rising creatinine, persistent fever, diarrhea, graft dysfunction, neurological changes, or any other symptoms without obvious cause and/or recipients who are not responding to typical therapies.