2659. Retrospective Review of Biopsy Proven Acute Graft Pyelonephritis in Renal Transplant Patients

BACKGROUND: There are few studies of histologic acute graft pyelonephritis (HAGPN) following kidney transplant (KT). The goals of this study are to determine incidence, identify potential risk factors and describe outcomes of HAGPN in a large cohort of KT recipients. METHODS: Renal allograft biopsies of all patients undergoing first KT at our medical center between 2008 and 2017 were reviewed. HAGPN was defined as the presence of neutrophils within the interstitium and tubules (casts). Medical charts of patients with HAGPN were reviewed. Episodes of bacteriuria (≥10:5 cfu/mL growth in culture) were classified as urinary tract infection (UTI) or asymptomatic bacteruria (ASB) based upon documented symptoms. An episode of acute rejection was defined as pulse parenteral immunosuppressive therapy for histologic evidence of rejection. RESULTS: HAGPN was identified in 43 of 1,391 (3.1%) KT recipients at a median of 298 days post-transplant. There were no significant differences between recipient age or gender, donor age or transplant type (deceased, living related, living unrelated) between recipients with and without HAGPN. Urologic malformation was diagnosed in 14 (33%) by day 30 post-transplant. Twenty-five (58%), 17 (40%), and 13 (30%) sustained one or more episodes of acute rejection, UTI and ASB, respectively, prior to HAGPN. At diagnosis of HAGPN, 28 (65%), 7 (16%), and 16 (37%) had histologic evidence of rejection, UTI and ASB, respectively. Twenty-two (51%) and 37 (86%) were treated with pulse immunosuppression and antibiotics, respectively. Median nadir serum creatinine before HAGPN was 1.1 mg/day while median serum creatinine at 6 and 12 months after HAGPN were 1.5 and 1.6. Three patients (7%) developed graft failure within 1 year after HAGPN. CONCLUSION: HAGPN is an infrequent complication of KT. A majority of patients with HAGPN have histologic evidence of rejection and either UTI or ASB at diagnosis, though over 40% have neither UTI nor ASB. When rejection accompanying HAGPN is routinely treated with pulse immunosuppression and antibiotic therapy is administered, graft function is preserved for most patients but a minority (7%) loses graft function within 1 year. Potential risk factors to be assessed in further study include post-transplant urologic dysfunction, acute rejection and UTI. DISCLOSURES: All authors: No reported disclosures.