Among the serum inflammatory markers, procalcitonin differed among all the groups; the highest values were observed in the BP (median 0.36 ng/mL; IQR: 0.12–1.5), followed by the VP (median 0.22 ng/mL; IQR: 0.1–0.52), and the AP (median 0.11 ng/mL; IQR: 0.08–0.16), whereas the CRP differed only between the bacterial and viral pneumonia (24.26 vs. 7 mg/L, with IQR: 7.7–66.9 and 2.3–22.7, respectively). Here, CRP is linked to viral pneumonia.