Urological manifestations of BK polyomavirus in renal transplant recipients.

OBJECTIVES: BK polyomavirus (BKV) disease in renal transplant recipients has become an increasingly problematic clinical entity. Complications of BKV disease lead to chronic allograft nephropathy and ultimately loss in greater than 50% of cases. We reviewed our experience with BKV disease over a 5-year period. PATIENTS AND METHODS: We performed 155 cadaveric and 168 live-related transplants between January 2000 and June 2005. During this period, seven patients had biopsy-confirmed BKV disease, which compromised the renal function of six cadaveric and one live-related renal transplant recipients. BKV was suspected as a potential cause of renal function deterioration after eliminating other possibilities. BKV was then confirmed by detecting viral DNA in urine samples by polymerase chain reaction (PCR) and visualizing viral particles in allograft biopsies by electron microscopy. RESULTS: The deterioration of allograft function in five renal transplant recipients was due to polyomavirus-associated nephropathy and two due to ureteric stenosis. Upon confirmation of BKV, overall immunosuppression was reduced or modified with follow-up of 5 to 44 months. However, additional rescue therapies were used to stabilize allograft function including ciprofloxacin, intravenous immunoglobulin, and leflunomide. One patient died and another lost his allograft due to non-compliance and reverted to hemodialysis, but renal function in the remaining five allografts has remained stable at higher serum creatinine levels. CONCLUSIONS: The management of BKV disease in renal transplant recipients is not yet clearly defined. However, early recognition of urological sequelae and modification of immunosuppressive therapy are essential to ensure adequate long-term function of these allografts.