Ask the Experts - Renal Transplant Recipient With Interstitial...
I would like to know of any experience with renal transplantation and interstitial nephritis with acute renal failure and polyoma virus infection (ie, strategies for treatment and outcome of allograft function). We have one such patient, 8 months posttransplantation with a serum creatinine of 3.4 mg/dL. The patient was on tacrolimus, sirolimus, and prednisone; the tacrolimus is being tapered.

Our view of polyoma virus infection of the transplanted kidney is that it represents a problem of over-immunosuppression. Unfortunately, the associated interstitial nephritis has been confused with rejection, leading to therapeutic errors. The first treatment is to reduce the immunosuppression; in this case, you might do well to stop the sirolimus, reduce the tacrolimus to levels of 5-7 ng/mL, and minimize or even stop the corticosteroids. You can follow the urinary polymerase chain reaction assay to assess whether the virus is disappearing, but you may need to repeat the biopsy of the kidney. If reduction of immunosuppression is not effective, we have used low-dose (0.25-33 mg/kg) intravenous cidofovir, with hydration before and during the administration (without probenecid) given every other week, and have been able to eradicate the virus in most of the handful of patients in whom we have tried this. Polyoma virus infection still represents a difficult problem in renal transplantation.