Cytomegalovirus in urinary sediment in patients with acute kidney injury

BACKGROUND: Immunosuppression in solid organ transplantation is associated with frequent infections. Renal allograft recipients are susceptible to opportunistic infections and can acquire human cytomegalovirus (HCMV) infections even within the allograft. There, HCMV can be found in both the glomerulus and tubular cells, but is mostly restricted to specific and circumscribed sites. Therefore, not all organ infections are identifiable by immunohistology for HCMV proteins in fine needle core biopsies. Thus, we performed a urinalysis study to search for HCMV-specific RNA transcripts in the urine sediment of patients with acute kidney injury. METHODS: Urinary sediment of 90 patients with acute kidney injury (AKI), including 48 renal transplant recipients (RTX) and 42 non-transplant recipients (nRTX), was collected from morning urine for RNA extraction and reverse transcription. The copy number of HCMV transcripts was evaluated using a UL132 HCMV-specific probe set and by real-time quantitative polymerase chain reaction (RT-qPCR). RESULTS: Of the 48 RTX patients, ten showed HCMV copies in their urine sediment cells. Within this group, three recipients had negative HCMV serology and received an allograft from an HCMV-seropositive donor. In addition, all three RTX patients on a belatacept-based immunosuppressive regimen had HCMV transcripts in their urine. Of the 42 nRTX patients, only two had detectable HCMV transcripts in urine sediment cells and both were under immunosuppression. CONCLUSIONS: Ten immunosuppressed renal allograft recipients and two immunosuppressed non-transplant patients with AKI showed HCMV copies in urine sediment. Thus, HCMV positivity in urinary sediment appears to be associated with immunosuppression. This study describes a novel noninvasive method for detection of HCMV in urinary sediment. Whether all HCMV infections can be detected or only those with viral replication warrants further investigation.