T2 and SeptiCyte RAPID Duration Project

Duration of Bloodstream Infection as Measured by Conventional Cultures Compared With Novel Culture Independent Systems and Persistence of Biomarkers Associated With Severe Infection

Infection with bacteria and other germs in the blood can be deadly. How long germs stay in the blood is important for two reasons. The first is that if they stay in the blood for many days it is a sign that antibiotics may need to be changed. The second is that if they stay in the blood for only a short time it may give doctors confidence to switch to tablets and consider early discharge from hospital. This study is evaluating the diagnostic and prognostic performance of two novel technologies when used to measure the duration of the bloodstream infection.

Bloodstream infection is highly significant and is associated with mortality rates of between 10 and 25%.

For some infection types (for example, Staphylococcus aureus) a longer duration of bacteria being present in the blood is linked to higher mortality. With traditional microbiologic techniques, bloodstream infection with gram-negative bacteria is usually quite brief. However, new culture independent bacteraemia detection systems (such as T2 magnetic resonance assay) are more sensitive than traditional blood culture systems and may show that gram-negative bacteraemia is more prolonged in some patients than has previously been thought. This observational study will investigate the correlation between the duration of bloodstream infection by mean of traditional blood culture techniques with:

1. Duration of the bloodstream infection by mean of the T2 magnetic resonance assay, a new culture independent bacteraemia detection system.
2. Persistence of inflammation as measured by the SeptiCyte RAPID test, a host response assay able to differentiate infectious from sterile inflammation.

The study will also correlate each measure of the duration of bacteraemia with microbiological and clinical outcomes.

Inclusion Criteria:

• Patients who have proven bloodstream infection with any T2-on panel pathogen (Enterococcus faecium, S. aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Candida spp.)

Exclusion Criteria:

• Palliative care approach
• Failure to give written informed consent (by patient or their legal representative)
• Polymicrobial index blood culture