The 2017 ESPID guidelines recommend switching to oral therapy after 2–4 days of intravenous antibiotic therapy if the patient presents an improvement in clinical conditions: apyrexia or decrease in body temperature for 24–48 h, improvement of symptoms, lack of signs referable to complications, 30–50% decrease in CRP (protein C-reactive) compared to the maximum value reached, negative culture tests and the absence of pathogens such as MRSA or PVL-SA (Panton-Valentine leucocidin positive S. aureus) that can cause more severe forms of osteomyelitis [6]. The gene discussed is CRP; the disease is osteomyelitis.