Late-Onset BK Viruria in Renal Transplant Recipients

Abstract

BackgroundMost cases of BK virus (BKV) infections emerge within the 1st years of kidney transplantation. We aimed to determine the prevalence of late-onset BKV infection and whether there are any differences between risk factors in early and late BKV infections. MethodsIn this single-center retrospective study, we reviewed 300 kidney transplant recipients that were under regular follow-up and selected recipients with BKV infection and recorded associated risk factors, connection with immunosuppression, and responses to modification of treatment. ResultsBKV was detected within the 1st 5 years after transplantation in 20 patients (6.6%, group 1) and after 5 years in 15 patients (5.0%, group 2). There were no significant differences between the 2 groups regarding age, sex, sex mismatches, donor type, BKV elimination time, serum creatinine, and estimated glomerular filtration rate at the times of BKV detection and last follow-up visit. In group 1, 2 recipients had biopsy-proven BKV-associated nephropathy (BKVAN), 3 recipients had BK viruria and viremia without BKVAN (biopsy proven), and 15 recipients (75%) had only BK viruria. In group 2, all of the patients had only BK viruria. In this group, on detection of BK viruria and immediate modification of immunosuppressive regimens prevented BK viremia. ConclusionsRoutine screening of renal transplant recipients for BKV was indicated not only during the 1st 5 years, but also for the full follow-up period after transplantation.