AbstractBackground: Sepsis remains a major cause of death incritically ill patients. Early recognition of sepsis and timelytherapeutic interventions are believed to be the cornerstone in outcome affection, however early identification of sepsis is not always straight forward since clinical signs and presentation can be misleading. Although blood culture remains the gold standard for diagnosis of bacterial infection, it still has several limitations and therefore the need for an early and specific diagnostic biomarker is mandatory. Procalcitonin is widely reported as a useful biochemical marker to differentiate sepsis from other non-infectious causes of systemic inflammatory response syndrome. Presepsin is a proposed early, sensitive, specific biomarker that may help early identification of sepsis.Aim of Study: This study was performed to compare theclinical usefulness of monitoring Presepsin and Procalcitoninserum levels in early diagnosis of sepsis.Patients and Methods: This prospective study was con-ducted at Ain-Shams University hospital, Cairo, Egypt. Weincluded 50 sepsis patients (age from 18-60 years old), whofulfilled two or more of the criteria for sepsis as defined bythe society of critical care medicine (SCCM). Full Historytaking, physical examination, baseline laboratory investigationsand required imaging scans were collected and recorded for all patients on admission to ICU. Blood cultures were obtained before initiating antibiotic therapy. Presepsin and procalcitonin serum values were measured at 6 time points: On ICU admission (T0), after two hours (T1), after four hours (T2), after 8 hours (T3), after 24 hours (T4) and after 72 hours (T5). Sepsis was confirmed by the patient's cultures, and were then compared to the corresponding serum values of Procalcitonin and Presepsin. Results were analyzed to determine the diagnostic efficiency of both biomarkers.Results: In the studied population, the mean age of allpatients was (54.3±15.6) years, with (52%) of patients werefemales; and (48%) were males. Regarding the outcome data, (60%) of patients showed positive culture results, and (40%)showed negative culture results. In our study we found asignificant increase in Presepsin level in the positive culturegroup compared to the negative culture group at all time points starting from T0 to T5. Concurrently we found markedincrease in Procalcitonin in positive group compared tonegative group starting from T2 to T5, while early measure-ments at T0 and T1 Procalcitonin rise was non-significant.ROC-curve analysis showed that early Presepsin level (after 2 hours) at a cutoff point (>379) showed a significant predictive power for early sepsis diagnosis, with good (82%) accuracy, sensitivity (100%) and specificity (80%) (p < 0.01). Early Procalcitonin level showed comparable sensitivity (90%) to Presepsin but much lower specificity (35%), and poor (56%) accuracy (p>0.05), making its predictive value for early distinguishing patients with positive cultures compared to patients with negative cultures statistically non-significant.Conclusion: To conclude, the present study suggests thatPresepsin and Procalcitonin are valuable biomarkers for sepsisdiagnosis. Furthermore, our findings demonstrate that Presepsinhas proven to be a promising candidate for accurate and earlyprediction of sepsis compared to Procalcitonin, giving prelim-inary indications that Presepsin may play an important rolein the early sepsis identification in suspected septic patients.