Cytomegalovirus infections in non-immunocompromised and immunocompromised patients in the intensive care unit

Infection, inflammatory response, activation of coagulation cascade and sepsis are tightly interconnected. In the initial phase, sepsis is characterized by a pro-inflammatory state, while in the late phase, by an anti-inflammatory state which favors cytomegalovirus reactivation. Cytomegalovirus infection would accentuate the sepsis-induced immunologic effects increasing the risk for other infections. The rate of CMV infection is 17% in critically ill nonimmunocompromised patients, up to 30% in hematopoietic stem cell transplant and up to 60% in solid organ transplant recipients. Cytomegalovirus infection in critically ill patients is associated with prolonged ventilator support, nosocomial infections, prolonged hospital and/or ICU stay and increased mortality. In immunocompromised patients, cytomegalovirus causes direct effects (viral syndrome, pneumonia, meningo-encephalitis, and gastro-intestinal tract involvement) and indirect (immunomodulatory) effects. These indirect effects would predispose the patients to secondary infections, delay immune recovery after hematopoietic stem cell transplant, and increase the risk of EBV-related B-cell lymphoproliferative disease and allograft rejection. Cytomegalovirus serology is not useful for the diagnosis of active infections. Cytomegalovirus culture is impractical for clinical purposes. The shell vial assay has low sensitivity. pp65 antigen is a sensitive and specific diagnostic method. Real-time PCR is more sensitive and specific (earlier detection) than pp65 antigen test and it is a more reliable marker to monitor the clearance of viremia. Ganciclovir and valganciclovir are the first-line antiviral therapies for the treatment of immunocompromised patients, while foscarnet and cidofovir are reserved mainly for treatment of ganciclovir-resistant cytomegalovirus infections.