To compare the value of presepsin, procalcitonin (PCT) and C-reactive protein (CRP) in differentiating different types of pathogenic bacteria in septic patients.

A prospective study was conducted to collect 322 septic patients who met the diagnostic criteria of "sepsis 3.0" in the Emergency ICU of the First Affiliated Hospital of Dalian Medical University from July 2016 to January 2018. According to the results of blood culture, patients were divided into the positive blood culture group (n=114) and negative blood culture group (n=208). Patients in the positive blood culture group were further divided into four subgroups: Gram-positive coccus (G⁺), Gram-negative bacilli (G^-), mixed bacteria, and fungi groups. Healthy volunteers were selected as the control group (n=45). The differences in presepsin, PCT and CRP levels were compared among the groups, and the curves of the subjects' working characteristic curve (ROC) were drawn.

Presepsin, PCT, and CRP were significantly increased in the positive blood culture and negative blood culture groups compared with the control group (all P<0.05); Presepsin and PCT were significantly higher in the positive blood culture group than those in the negative blood culture group (both P<0.05). There was no significant difference in Presepsin among the four subgroups in the positive blood culture group (all P>0.05), but PCT was significantly higher in the G^- and mixed bacteria groups than that in the G⁺ and fungi groups (all P<0.05). Presepsin predicted a positive blood culture with area under ROC curve of 0.680, which was higher than PCT (AUC=0.599).

Presepsin is more valuable than PCT in early predicting positive blood culture in septic patients, but only PCT has an ability to differentiate pathogenic bacteria in septic patients with positive blood culture. It suggested that a combination of Presepsin and PCT should be more meaningful in clinical practice.

Sepsis; Presepsin; Procalcitonin; C-reactive protein; Gram-positive coccus; Gram-negative bacilli; Fungi