Effective Use of PCR for the Detection of Cytomegalovirus Viremia and Monitoring Therapy in Immunocompromised Patients

To establish criteria for the most productive use of quantitative cytomegalovirus (CMV) polymerase chain reaction (PCR) in transplant and HIV patients, both for diagnosis and monitoring infections. We evaluated the medical records of 108 HIV, bone marrow transplant (BMT), and solid organ transplant (SOT) patients who had positive CMV viral load tests. Cytomegalovirus was detected at median of 47 and 183.5 days after BMT and SOT, respectively. All HIV patients who had positive CMV viremia had CD4 cell counts <175 cells/μL, and all HIV patients with end-organ disease had CD4 cell counts <75 cells/μL. The median time for CMV to become undetectable after treatment was 22, 21, and 31 days for HIV, BMT, and SOT patients, respectively. Cytomegalovirus viral load screening focusing on high-risk periods may be cost effective. A CMV viral load does not decrease rapidly with treatment. The CMV PCR for monitoring therapy should not be performed more than once a week.