Even though elevated PCT serum concentrations are not exclusive to infections (they can also be elevated during paraneoplastic processes and in patients with solid tumours or with major trauma [37]), at this moment, PCT is considered among the best clinically available biomarkers to diagnose sepsis in routine praxis [38] and can be used as a guide to fulfil the principles of antimicrobial stewardship (AS). The gene discussed is CALCA; the disease is infection.