Optimal Duration of the Antibiotic Therapy Based on Biomarker Testing

The criteria for initiating antibiotic therapy and its optimal duration have been the subject of considerable expert debate and recommendations in recent decades. The impact in terms of public health is major, in order to avoid the emergency of highly resistance strains. Recently, biomarkers have garnered substantial interest, firstly thanks to advances in biotechnology, and secondly, due to the low level of evidence underlying the guidelines, and the absence of a standardized definition of clinical response. Among the many biomarkers that have been evaluated, procalcitonin (PCT) has been the subject of numerous publications investigating the optimal duration of antibiotic therapy, with encouraging results in selected groups of patients. Using a decisional algorithm, with reference values for day 1, days 2-3, and every 48 hours thereafter could make it possible to discontinue antibiotic therapy if the PCT value is < 0.25 mu g/l on day 3 or beyond (or a decrease of > 80% compared to the peak value) in patients hospitalized for respiratory tract infections, and < 0.5 mu g/l (or a decrease of > 80% compared to the peak value) in patients admitted to the intensive care unit without bacteraemia and with a known site of infection. The medical community eagerly awaits new and promising biomarkers, but also a technology that can be made available at the bedside.