Clinical utility of a quantitative polymerase chain reaction for diagnosisof cytomegalovirus disease in solid organ transplant patients

Background. Accurate and rapid diagnosis of human cytomegalovirus (HCMV) di sease in solid organ transplant patients remains a challenge. We evaluated the clinical utility of a quantitative polymerase chain reaction (QPCR) met hod to diagnose transplant patients with HCMV disease. Methods. A total of 429 plasma samples from 121 solid organ transplant pati ents were prospectively collected and evaluated for HCMV using a QPCR assay . To enhance the sensitivity of the QPCR assay, plasma samples were centrif uged in a manner designed to concentrate the virions before nucleic acid ex traction. Quantitation was achieved by co-amplifying an internal quantitati ve standard (IS) that contained the same primer sequences as for HCMV. Poly merase chain reaction products were detected by hybridization to 96-well mi crotiter plates coated with either a HCMV- or an IS-specific probe, Results. A total of 103 patients had all samples negative by QPCR, None of the 103 patients developed HCMV disease during the study. In contrast, 18 p atients showed at least 1 sample positive by the QPCR assay, but only 8 of these developed HCMV disease. The mean viral load value for patients withou t HCMV disease was 93 viral copies (vc) per mi of plasma (range: 35-325 vc/ ml plasma) and for the 8 patients with HCMV disease was 67,686 vc/ml plasma (range: 167-1,325,000 vc/ml plasma) (P<0.001). Using a cut-off value of 10 0 vc/ml plasma and clinical diagnosis of HCMV disease, the QPCR assay showe d a sensitivity of 100% and specificity of 99.1%. Conclusion. HCMV viral load may be useful in the diagnosis of HCMV disease in solid organ transplant patients.