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

Objective: 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. Method: 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. Results: 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/mu L, and all HIV patients with end-organ disease had CD4 cell counts <75 cells/mu L. The median time for CMV to become undetectable after treatment was 22, 21, and 31 days for HIV, BMT, and SOT patients, respectively. Conclusion: 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.