Human Neutrophil Lipocalin as an Aid in the Diagnosis of Bacterial Infection in the Emergency Department

The aim of this study is to improve the medical care of patients with infections for which the cause cannot be clearly identified as bacterial or viral. To achieve this, we are investigating a new inflammatory marker in the blood that may help identify severe bacterial infections more quickly. Early detection is important to prevent complications and ensure that patients receive the most appropriate treatment as soon as possible. This is an observational study. The knowledge gained from this study may help improve the care of patients with infections of unclear origin by supporting faster diagnosis, earlier treatment, improved risk assessment, and better planning of follow-up care.

Inclusion Criteria: * Adults presenting to the Emergency Department with suspected infection * Written informed consent provided prior to enrolment * Evidence of significant physiological disturbance, defined by abnormal vital signs requiring further medical assessment * Symptoms suggestive of a respiratory tract infection (e.g. cough with sputum, worsening cough, or breathing difficulties) * Symptoms suggestive of a urinary tract infection (e.g. pain during urination, frequent urination, or urgency) * Pain, redness, warmth, or discharge at the site of a vascular catheter or intravenous line * Signs of a skin or soft tissue infection, including pain, tenderness, swelling, redness, warmth, or pus formation * Nausea, vomiting, abdominal pain, or jaundice suggestive of a possible abdominal infection * Headache, neck stiffness, or other symptoms suggestive of a central nervous system infection * Abnormal vital signs corresponding to a National Early Warning Score (NEWS) of ≥3 points Exclusion Criteria: * Known pregnancy at the time of study enrolment * Antibiotic treatment that started more than 24 hours before presentation to the Emergency Department * Inability or unwillingness to provide written informed consent for study participation