Comparison of cytomegalovirus antigenemia and culture assays in patients on and off antiviral therapy

Abstract

We examined 1,869 consecutive blood specimens from 529 patients (>80% organ transplant recipients) for detection of CMV by antigenemia and culture assays, and compared results between patients on and off antiviral therapy. All 1,869 specimens were tested by the shell vial assay and antigenemia, and 503 were also tested by standard tube culture. The overall positivity rate for each test was 17.0% for antigenemia, 1.8% for shell vial culture assay, and 0.7% by tube culture. No specimens were positive by either shell vial or tube culture, while negative by antigenemia. These findings were consistent across all organ transplant and other patient types. Shell vial positivity was associated with higher antigenemia levels in patients either on or off anti-CMV drug therapy. Among the shell vial positive specimens, the antigenemia counts were higher in patients on antiviral drug therapy as compared to those not on therapy. We conclude that the pp65 antigenemia assay is superior to culture methods for detection of CMV in blood, particularly for patients on anti-CMV drug treatment. Additionally, its quantitative nature renders the antigenemia assay an excellent tracking tool for both resolution of asymptomatic, low level CMV reactivations and response of CMV infection to antiviral treatment.