ICU-acquired immunosuppression and the risk for secondary fungal infections

Sepsis and related infectious syndromes, including nosocomial infections, represent a major but largely under recognized healthcare problem worldwide, accounting for thousands of deaths every year. After a short pro-inflammatory phase, severely injured ICU patients enter a stage of protracted immunosuppression illustrated by reactivation of dormant viruses or infections due to microorganisms, including fungi, which are normally pathogenic solely in immunocompromised hosts. This brief review will focus on immune dysfunctions described so far in ICU patients regarding monocytes and T lymphocytes (as examples for innate and adaptive immune cells) and on their potential use as biomarkers for identification of patients at risk of secondary nosocomial infections and for guidance of immunotherapy. Finally, we will more specifically focus on the risk for fungal infections in ICU patients, and on the potential beneficial effects of adjunctive therapy not only to prevent these infections, but also to reinforce immune responses once they are already diagnosed.