To study the Diagnostic Accuracy of Procalcitonin and C-Reactive Protein in Sepsis with special reference to its Microbial Etiology and Antimicrobial Biomarker Profiles in Blood Culture Positive Sepsis Patients

Abstract

Background: Early and accurate diagnosis of sepsis is critical for prompt management and improved prognosis. Procalcitonin (PCT) and C-reactive protein (CRP) are widely used biomarkers for infection, but their comparative diagnostic utility in culture-positive sepsis requires further evaluation.

Objective: To assess the diagnostic accuracy of PCT and CRP in sepsis and septic shock, and to correlate biomarker levels with blood culture findings.

Methods: A case-control study was conducted on 80 participants, comprising 40 sepsis patients and 40 age- and sex-matched healthy controls. Demographic data, blood culture results, and PCT and CRP levels were recorded. ROC curve analysis determined the sensitivity, specificity, and optimal cut-off values.

Results: The mean age was significantly higher in the sepsis group compared to controls (54.8 ± 18.9 vs 46.3 ± 15.4 years; p<0.01). Blood culture was positive in 13 (32.5%) patients, with Gram-negative bacteria predominating (84.6%), particularly Escherichia coli (38.5%). Culture-positive patients had significantly higher PCT levels (median 8.96 ng/ml) compared to culture-negative (1.99 ng/ml) and controls (0.049 ng/ml). CRP levels were also elevated in culture-positive patients but showed less discriminatory power. PCT demonstrated excellent diagnostic accuracy for sepsis vs control (AUC 0.93) and moderate accuracy for culture-positive vs culture-negative (AUC 0.79). CRP had lower discriminatory capacity (AUC 0.85 for sepsis vs control; 0.53 for culture-positive vs culture-negative).

Conclusion: PCT is a superior biomarker to CRP for distinguishing sepsis from controls and for differentiating culture-positive from culture-negative sepsis. Its early application may enhance diagnostic precision and improve patient outcomes.