A comparison of infection indexes among different bacterial infection groups shows that PCT of patients infected with Gram-negative bacteria was significantly higher than that of patients infected with Gram-positive bacterial infections (p < 0.05), but there was no significant difference in CD64 index, CD64 positive rate, and CRP indexes between the two groups (all p > 0.05), as shown in Table 3. Here, CALCA is linked to gram-positive bacterial infections.