The prognostic significance of positive CMV cultures during surveillance of renal transplant recipients.

Renal transplant recipients are at risk of severe morbidity and mortality from CMV disease. We have undertaken routine surveillance for CMV shedding on 133 transplant recipients, using a rapid culture technique, in order to assess the incidence of CMV infection and disease in these patients and to assess the prognostic significance of detection in whole blood, throat swab specimens, or urine. Donor CMV seropositivity was associated with posttransplant CMV infection (P < 0.05) and disease (P = 0.06). CMV infection and disease were associated with the receipt of anti-T-cell antibodies (P < 0.0001 and P = 0.08, respectively). First shedding of virus from any site occurred earlier posttransplant in those recipients who developed disease (median 39 days) than in those who did not (median 55 days)(P < 0.05). Detection of virus in blood occurred at a median time of 16 days before onset of symptoms, compared with 9 days before symptoms in urine, and 3 days after onset of symptoms from throat swab. A positive blood culture represented a relative risk of 7.1 for the subsequent development of disease, compared with 2.1 and 1.8 for positive urine and saliva cultures, respectively. The addition of urine cultures to blood cultures increased the sensitivity for identification of those at risk--however, the relative risk was reduced to 5.8. We conclude that routine surveillance for CMV shedding, especially in blood and urine, can identify recipients at high risk of CMV disease, and propose a trial in which those with asymptomatic viremia are allocated to receive ganciclovir or placebo, in order to assess the efficacy of "preemptive" therapy in this group of patients.