Tubulointerstitial Nephritis Post-Microsporidium Infection in a Combined Liver-Kidney Transplanted Patient: A Case Report.

Microsporidia are emerging opportunistic pathogens in immunosuppressed individuals, including solid organ transplant recipients. We present a case of tubulointerstitial nephritis (TIN) caused by Microsporidia infection in a 55-year-old male who underwent combined liver-kidney transplantation (CLKT) for metabolic-associated fatty liver disease and end-stage kidney disease. The patient developed diarrhoea, abdominal bloating and acute kidney injury (AKI) 1 month post-transplant. A kidney biopsy revealed granulomatous TIN with 50% interstitial fibrosis and 60% tubular atrophy. Stool examination confirmed Microsporidia infection. Treatment with albendazole over 6months led to gradual renal function recovery. This case highlights the risk of Microsporidia infections in CLKT recipients, presenting as a rare but serious cause of graft dysfunction and AKI. Early diagnosis and treatment, including reduction in immunosuppression and antiparasitic therapy, are essential for improving outcomes in these patients. To our knowledge, this is the first report of Microsporidia infection in a CLKT recipient globally.