New biomarkers for respiratory infections.

Purpose of review Although pneumonia, either community or hospital-acquired, is the most frequent severe respiratory infection, it is an infection difficult to diagnose. At present, the diagnosis of pneumonia relies on a combination of clinical, radiologic, and microbiologic criteria. However, these criteria are far from perfect leading to uncertainty in the diagnosis, risk stratification, and choice of antibiotic therapy. Biomarkers have been used to bring additional information in this setting. Recent findings The aim of this review is to provide a clear overview of the current evidence for biomarkers to distinguish between patients in several clinical scenarios: to exclude pneumonia in order to withhold antibiotics, to identify the causative pathogen to target antimicrobial treatment, to identify phenotypes of inflammatory response to facilitate adjunctive treatments, to stratify the risk of severe pneumonia and provide the adequate level of care, and to monitor treatment response and de-escalate antibiotic therapy. Summary In recent years the number of new biomarkers increased markedly in different areas like pathogen identification or host response. Although far from the ideal, there are several promising areas that could represent true evolutions in the management of pneumonia, in the near future.