Biomarkers to improve diagnostic and prognostic accuracy in systemic infections

We review the advantages and drawbacks of biomarkers in the diagnostic and prognostic assessment of systemic infections.

Since the signs and symptoms of severe infections can be ambiguous, biomarkers provide a more reliable tool in ascertaining the presence of a relevant bacterial infection, its severity and treatment response. Procalcitonin and, to a lesser extent, C-reactive protein and interleukin-8 can improve the diagnostic assessment of infections and guide antibiotic therapy. Promising prognostic biomarkers include cortisol, proadrenomedullin, copeptin and natriuretic peptides. The strengths and weaknesses of biomarkers must be recognized in order to use them rationally and safely. Cutoff ranges of biomarkers must be chosen according to the specific clinical context and they should be used as a complementary tool, to reinforce the clinical diagnostic workup. Biomarkers cannot determine the causative organisms and associated patterns of antibiotic susceptibility.

If used in the proper setting, serial measurements of diagnostic biomarkers may allow treatments to be adjusted at an early stage in patients with severe infections. This may involve either intensifying treatment when infection levels stay high or avoiding unnecessary prolonged courses of antibiotics when levels rapidly decrease, thereby improving the allocation of healthcare resources.