Predictive role of selected biomarkers in differentiating gram-positive from gram-negative sepsis in surgical patients: a retrospective study

Introduction:
Patients after major surgery are at high risk of developing sepsis, which is accompanied by elevated serum levels of C-reactive protein (CRP) and procalcitonin (PCT). This study aimed to examine the differences in serum biomarker levels concerning the causative agent of sepsis in surgical patients.

Material and methods:
A retrospective study was carried out in the surgical intensive care unit (ICU) and included 81 septic patients admitted from January 2019 to May 2022, who had positive blood cultures (BC). Serum levels of PCT, CRP, white blood cells (WBC) and platelet counts were recorded on the day of the positive BC and over the following 3 days.

Results:
Patients with gram(–) sepsis had significantly higher PCT levels, and lower platelet count compared to patients with gram(+) sepsis. High PCT and low platelets levels in all measurements were a significant predictor of gram(–) isolate with the highest predictive value on the third day after BC sampling, with AUROC 0.821 (95% CI: 0.692–0.950), P = 0.001, and AUROC 0.676 (95% CI: 0.541–0.811), P = 0.02, respectively. In multivariate logistic regression, platelets the day after BC sampling and PCT on the third day made a significant contribution in distinguishing gam(+) from gram(–) BC. Age and high serum CRP levels were significant predictors of poor outcomes.

Conclusions:
PCT and platelets may be useful biomarkers for predicting the causative agent of sepsis in surgical patients.