Double trouble: concurrent cytomegalovirus and BK polyomavirus infections in a patient who underwent kidney transplantation

A 19-year-old student, who had received a kidney from her mother and had moderate cytomegalovirus (CMV) infection risk, received triple immunosuppression (IS) with corticosteroids, tacrolimus, and mycophenolate sodium (MPS). The patient was treated with pulse corticosteroids for borderline rejection at 1-month posttransplantation, but subsequently developed a urinary tract infection, which was resolved with intravenous administration of antibiotics. In the 4th month after transplantation, the patient was diagnosed with hydronephrosis secondary to a ureteric stricture, which required surgery. Simultaneously, her BK polyomavirus-nucleic acid titer (BKV-NAT) and CMV-NAT increased to 391 IU/mL and 241 IU/mL, respectively. Accordingly, her MPS dosage was reduced and, ultimately, withheld. While her CMV-NAT decreased to undetectable levels; her BKV-NAT titer remained persistently high (14,743 to 22,088 IU/mL). The everolimus was then added to minimize tacrolimus exposure, and her BKV-NAT titer subsequently reduced to 2,575 IU/mL. Simultaneously her renal allograft biopsy showed severe tubulitis with macronuclei positivity for simian virus 40 which indicated the presence of BKV. Besides, the typical CMV associated cytoplasmic and nuclear eosinophilic inclusions also seen in the immunohistochemical analyses. Oral valganciclovir and intravenous immunoglobulin were then administered to the patient and her kidney function partially improved subsequently. She was later discharged without any clinical evidence of rejection.