Biomarkers of infection and its complications in the critically ill

__Abstract__ Microbial infections, and associated complications, are still an important cause of intensive care (ICU) admissions and mortality Despite the use of antibiotics and guidelines for supportive care mortality rates are up to 50% depending on disease severity. The most widely accepted definitions for infection are those of the “International Sepsis Forum Consensus Conference on Definitions of Infection in the Intensive Care Unit” (ISFCC).8 According to ISFCC criteria the likelihood of infection is based mainly on clinical suspicion and/or microbiological cultures. In clinical practice new onset fever, leukocytosis, tachypnea, tachycardia and elevated C-reactive protein (CRP) levels raise suspicion about the presence of infectious disease. They are, however, markers of host inflammation and their value for the definite diagnosis of infection has considerable limitations, especially in the ICU. The combination of fever, leukocytosis, tachypnea and tachycardia is considered the systemic inflammatory response syndrome to infection (SIRS). An infection in the presence of SIRS is called sepsis (Table 1). The adverse sequelae of infection: sepsis, septic shock, and organ failure, are partly caused by this host inflammatory response and each negatively influences outcome. In fear of undertreatment physicians repeatedly order cultures and start broad spectrum, empiric antibiotic treatment. However, overtreatment unnecessarily exposes patients to the risk of adverse drug reactions, amongst other risks. Prolonged antibiotic therapy also results in bacterial selection in individual patients and microbial resistance on a population leve