Usefulness of urine and blood cultures for diagnosing cytomegalovirus infection in the kidney transplant recipient

Objective. To prospectively and comparatively study the usefulness of urine (viruria) and blood (antigenemia pp65 and culture) (viremia) for the diagnosis of cytomegalovirus (CMV) infection in renal transplant (RT) recipients. Material and methods. All RT recipients at our hospital were studied from January 1995 to December 1996. After decontamination, urine specimens were inoculated into two MRC-5 cell line vials. Polymorphonuclear cells were extracted from peripheral blood by sedimentation in saline dextran and were used for antigenemia pp65 test and for culture in shell-vial. Results. A total of 1,335 specimens from 43 patients were studied. CMV was recovered from 110 out of the 913 (12%) urine specimens and from 101 out of the 422 (23.9%) blood specimens (antigenemia and/or viremia). CMV detection was first obtained by a positive blood test in 23 patients (88.4%), whereas the urine specimen was the first positive test in only three (11.6%) patients (p = 0.0001). A positive result in blood preceded a positive result in urine by a mean of 10.3 days (range: 2-73 days). Antigenemia and viremia were simultaneously positive in 61.5% of patients. In three patients a positive antigenemia preceded viremia by 14 days. In seven patients (26.9%) only the shell-vial culture was positive. Culture preceded antigenemia by a mean of 7.6 days. In the 26 patients, the time elapsed until the first positive blood specimen for CMV was 37.3 days (range: 11-88 days). Conclusion. According to the results obtained we believe that blood (antigenemia pp65 and/or viremia) should be considered as the only really useful specimen for the diagnosis of infection/disease caused by CMV in RT recipients. The urine specimen lacks a diagnostic and clinical usefulness and therefore should not be used in these patients.