The optimal cut-off values to predict bacterial co-infection according to Youden’s J statistics in the studied cohort are CRP = 220 mg/L (SE = 0.524; SP = 0.806), PCT = 0.8 μg/L (SE = 0.667; SP = 0.944), and IL-6 = 40 ng/L (SE = 0.714; SP = 0.750). Here, IL6 is linked to coinfection.