Abstract: SA-PO1156
Encephalitozoon cuniculi Infection Presenting as Granulomatous Interstitial Nephritis in a Kidney Transplant Recipient
Session Information
- Transplantation: Clinical - Infectious Diseases
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2002 Transplantation: Clinical
Authors
- Lee, Deborah, University of California San Francisco, San Francisco, California, United States
- Laszik, Zoltan G., University of California San Francisco, San Francisco, California, United States
- Brar, Amarpali, University of California San Francisco, San Francisco, California, United States
Introduction
Microsporidia are rare opportunistic intracellular parasites that affect immunocompromised hosts, including solid organ transplant recipients. We present a case of disseminated Encephalitozoon cuniculi infection causing granulomatous interstitial nephritis and severe acute kidney injury (AKI) in a recent kidney transplant recipient.
Case Description
A 27-year-old woman with end stage kidney disease secondary to autosomal dominant polycystic kidney disease underwent living unrelated renal transplantation. Six months post-transplant and shortly after receiving treatment for borderline acute cellular rejection, she developed AKI with creatinine elevation from baseline 1.7–2.0 mg/dL to 4.3 mg/dL, accompanied by fever and dysuria.
Infectious evaluation including CMV, BK virus, adenovirus, blood cultures, and urine cultures was negative. Allograft biopsy demonstrated severe tubulointerstitial nephritis with granulomatous and focally necrotizing features. Numerous 1–1.5 µm sized intracellular organisms were identified within tubular epithelial cells and granulomatous inflammatory foci. Organisms stained positive with Warthin-Starry, raising concern for microsporidian infection. Plasma mNGS (metagenomic next-generation sequencing) subsequently identified Encephalitozoon cuniculi.
Given these findings, immunosuppression was reduced and albendazole therapy was initiated. Fever resolved and renal function improved rapidly following the initiation of treatment.
Discussion
Encephalitozoon cuniculi infection is a rare cause of granulomatous interstitial nephritis and allograft dysfunction in kidney transplant recipients. Clinical manifestations may overlap with acute rejection, calcineurin inhibitor toxicity, and opportunistic infections, creating a diagnostic challenge. Recognition of characteristic histopathologic findings and use of adjunctive molecular diagnostics such as mNGS are important for timely diagnosis. Early treatment with albendazole combined with reduction of immunosuppression may help preserve allograft function.
H&E and Warthin-Starry stain of the allograft