The study aims to evaluate the test in this environment as a potential diagnostic. All patients will be screened using the electronic patient management system within the ED.

A single sample of approximately 20ml of blood, will be obtained at the same time as a clinically indicated blood culture (triggered by clinician concern for infection). The sample will be processed as described in the laboratory manual, aliquoted and frozen for future batch analysis. This analysis will include:

• The Mologic Biomarker Panel
• PCT
• CRP
• Other inflammatory markers or pathogen detection that may augment the panels accuracy

All conventional standard of care testing will be done at the study site as part of the enrolled subject's routine clinical care.

Two patient populations admitted to the CCU will be approached for inclusion into the study:

• Patients being managed for potential infection
• Patients having undergone elective major surgery and admitted to the CCU as part of their care pathway. These patients will act as controls as the majority show signs and symptoms of inflammation but rarely develop an infection.

Patients with potential infection: UCLH Critical Care Unit has approximately 1000 emergency admissions per year. Complicated infection (sepsis or septic shock) being the commonest underlying reason for admission.

UCLH Critical Care admits approximately 1000 patients per year following major elective surgery. These patients frequently exhibit the features of SIRS but the incidence of infection/sepsis is low (approximately 5%) and very rare in the first 3 days' post-surgery. This group is to be studied as a negative control group to ensure the Mologic Biomarker Panel is able to detect the difference between the similar inflammatory phenotypes developed through infection and surgical trauma.

In brief the proposed biomarkers will be measured in the laboratory of Mologic . These will initially be performed using standard lab assays (Enzyme Linked Immunosorbent Assays, ELISA). Biomarkers that show promise will then be mounted on a novel lateral flow device (under development), that could ultimately be deployed at the patients bedside.

Research assay will be used to test for the investigational Mologic biomarker panel and these results will be assessed using the results obtained from conventional testing used to identify infection (such as white cell count and CRP), in order to find a clinical association with the mologic biomarkers and patients with infections.