The factors allowing for an early switch to oral antibiotics include the absence of complications (such as sepsis, haematogenous spread of the infection to other organs (pneumonia) and deep vein thrombosis), the absence of fever for at least 48 h, a significant clinical improvement (reduced or absent pain and erythema), a significant reduction in inflammatory markers (30–50% decrease in CRP levels), the absence of virulent microorganisms (such as Salmonella, MRSA, or PVL+ S. aureus), and the absence of pathogens in the repeated blood culture (if initially present) [3,54]. This evidence concerns the gene CRP and susceptibility to pneumonia measurement.