Biomarkers as a guide for antimicrobial therapy

The use of biomarkers might help to avoid antibiotic misuse and overuse and to curb the rising incidence of microbial resistance. Amongst >100 biomarkers proposed for use as infection/sepsis markers, procalcitonin is the most frequently evaluated. It has been tested in 11 randomised controlled trials with more than 3500 patients and resulted in a considerable 35–70% reduction in antibiotic use without an apparent negative impact on patient outcome. Testing was carried out in hospital, Intensive Care Unit, emergency and primary care settings; most of the patients had lower respiratory tract infections and only smaller studies exist in surgical patients with infectious complications, immunocompromised patients and patients with sepsis. There are, however, concerns – trials designed to show non-inferiority of procalcitonin to standard management allowed rather large differences for mortality rates, in the range of 7.5–10%, thus clinically relevant excess mortality by procalcitonin-guided antibiotic therapy cannot be completely ruled out. Marker panels derived from transcriptomic or proteomic profiling hold promise in overcoming the limitations of procalcitonin for differentiating non-infectious from infection-associated inflammation. However, the utility of these novel diagnostic tools in the clinical setting remains to be proven.