Routine BK Virus Surveillance in Renal Transplantation - A Single Center's Experience

Background. We started a universal screening of all our kidney transplant recipients for BK virus in 2005. This review of our experience includes patients with months' posttransplantation follow-up. Methods. We performed a retrospective chart evaluation of all kidney transplants from January 2005 to February 2010. Urine polymerase chain reaction (PCR) for BK virus was done on all patients starting from 4 weeks after transplantation. If negative, it was repeated monthly for the first 6 months and then every 3-4 months. If the test was positive, a urine and blood BK virus PCR done on the next visit was repeated every 2-4 weeks with a slow reduction in immunosuppression. Results. From January 2005 to February 2010 we performed 173 kidney transplantations with 12 graft losses within the first 6 weeks which were excluded from the analysis. Induction immunosuppression consisted of anti-interleukin-2 receptor antibody (n = 102) or antithymoglobulin (ATG; n = 59). In 112 patients (70%), the urine BK virus PCR remained negative; 18 (11%) only the urine was positive and among an additional 31 (19%) BK virus PCR was positive in blood. There was no difference in incidence according to induction therapy. Delayed graft function was observed among 39 patients (24%); there was no difference in the incidence of BK virus with versus without DGF. The mean time to first detection was shorter with ATG induction (mean, 199 days; median, 90 days; range, 26-1198 days) compared with anti-IL-2 (mean, 321 days; median, 195 days; range, 23-1077 days). Urine-only positivity was first detected from 37 to 1198 days (mean, 366 days; median, 227 days) and blood positivity from 23 to 1069 days (mean, 216 days; median, 90 days). Among BK-positive patients, 26 (53%) were detected within the first 6 months and 38 (76%) within the first year. With reduction in immunosuppression, there was gradual reduction or elimination of positive PCR tests in all cases except one, which resulted in graft failure. Conclusions. Routine BK virus surveillance is effective; it tends to detect BK virus replication early, allowing reduction of immunosuppression, which results in good outcomes with renal preservation.