Biomarkers and infection in the emergency unit

The emergency unit is one of the main places for acute medical care and therefore, has a pivotal role in determining a diagnosis of bacterial infection and initiating antibiotic therapy. There is an unquestionable and growing interest for infection biomarkers because of the polymorphism of septic state presentations in the emergency unit and the lack of accuracy of available biological tools. The C Reactive protein (CRP) is a biomarker of inflammation, not of infection. CRP is highly sensitive but lacks specificity. Moreover, there are few interventional studies evaluating its true added diagnostic value in the emergency unit, therefore preventing using CRP as a biomarker of infection. Serum procalcitonin (PCT) dosage is more specific for the diagnosis of bacterial infection. PCT levels do not increase or only slightly in non-bacterial inflammatory syndromes. PCT also provides prognostic information and risk stratification assessment in the emergency unit. Moreover, many authors of interventional studies have validated the contribution of PCT in decision taking for antibiotic therapy when suspecting low respiratory tract infection. It is currently the first-line biomarker of infection in the emergency unit. Other biomarkers such as presepsin (sCD14) may be contributive for the diagnosis and prognosis.