Clinical Research Directory

Inclusion Criteria: 1. Age: Adult patients (≥ 18 years old) presenting to the EDs of the participating sites. 2. Clinical Suspicion of Infection: A high clinical suspicion of infection as determined by the attending emergency physician, accompanied by either a Systemic Inflammatory Response Syndrome (SIRS) score ≥ 2 or a Quick Sequential Organ Failure Assessment (qSOFA) score ≥ 2. Rationale: This dual-criteria strategy (SIRS or qSOFA) reflects a pragmatic, high-sensitivity approach designed to capture the full spectrum of sepsis in the emergency setting, overcoming the sensitivity limitations of using a single scoring system. 3. Feasibility of Biomarker Collection: Ability to obtain blood samples for IG and Presepsin measurement within 2 hours of ED arrival. 4. Informed Consent: Provision of written informed consent obtained from the patient or their legally authorized representative (LAR). Exclusion Criteria: 1. Severe Immunosuppression: Active chemotherapy, history of organ transplantation, or long-term high-dose corticosteroid therapy that may confound leukocyte kinetics or suppress systemic inflammatory responses. 2. Hematological Conditions: Documented hematological malignancies or myelodysplastic syndromes (MDS) capable of altering baseline IG profiles. 3. Pregnancy or lactation, due to the potential for pregnancy-induced physiological and immunological variability. 4. Prolonged Prior Hospitalization: Patients transferred from another facility after an admission of \>24 hours, as extensive prior intervention may obscure the hyper-acute biomarker kinetics critical for early diagnosis. 5. Consent Issues: Refusal to provide informed consent by the patient or their LAR.