Laboratory diagnosis of cytomegalovirus infection and disease in immunocompromised patients

Purpose of review To review new developments in PCR technology as they apply to detecting cytomegalovirus viremia and pneumonia, recent advances in detecting CMV resistance to antivirals and assays of specific CMV lymphocyte function. Recent findings This review summarizes the attempts to use real time PCR for cytomegalovirus deoxyribonucleic acidemia and to compare it to conventional PCR and antigenemia, it also reviews the use of quantitative PCR on bronchoalveolar lavage to assist in the diagnosis of CMV pneumonia. Phenotypic assays of susceptibility in tissue culture are much too slow to assist clinical decisions, taking weeks for completion. Genotypic assays may be performed directly on clinical samples such as blood, and cerebrospinal fluid and can be done by sequencing in a very few days. Finally, assays of lymphocytic functional responsiveness to cytomegalovirus can be used to identify transplant recipients at continuing risk for cytomegalovirus disease. Summary Assays for CMV DNA or antigen in blood are superior to culture for documenting viremia and pneumonia. Genotypic assays have largely replaced phenotypic assays for CMV resistance to antivirals. Lymphocyte responses to CMV antigen(s) may identify patients at risk for CMV disease.