This is a study to evaluate the diagnostic performance of the investigational Cytovale System & IntelliSep Test as a diagnostic marker of sepsis in a population of patients presenting to the emergency department with signs or suspicion of infection compared to retrospective physician adjudication, per the sepsis 3 definition, of those patients.

This is a multi-site prospective study to evaluate the diagnostic performance of the investigational Cytovale System & IntelliSep Test for patients presenting to the Emergency Department with signs or suspicion of infection. The IntelliSep Test is a microfluidic test that measures the biophysical properties of human leukocytes in conjunction with other laboratory findings and clinical assessments to aid in the early detection of sepsis with organ dysfunction occurring within the first three days after the blood sample collection.

Inclusion Criteria:

1. ≥ 18 years old
2. The first vital sign (any one of: blood pressure, temperature, pulse or respiratory rate) has been recorded in the medical record
3. A 300µl blood sample originally collected in a K2 EDTA (hematology purple top) tube within 4 hours of the first recorded vital sign is available.
4. Sign or suspicion of infection, defined as meeting either of criterion A-1 and A-2 (based on temperature, WBC, heart rate, respiratory rate and/or culture order criteria):

Exclusion Criteria:

1. Patients in whom a palliative care or hospice course is expected during ED visit
2. Self-reported, documented or otherwise known to be actively enrolled on any experimental/investigational therapeutic medication prior to blood collection
3. Self-reported, documented, or known history of a hematologic malignancy (any leukemia, lymphoma, or myeloma), myelodysplastic syndrome, or myeloproliferative disorder
4. Self-reported, documented or otherwise known to receive a chemotherapeutic agent or other excluded medication in the past 3 months (Appendix C)
5. Self-reported, documented or otherwise known to have undergone a hematopoietic stem cell transplant or any solid organ transplant
6. Patients transferred to the Emergency Department from another acute care facility
7. Residents or patients of a hospital-based skilled nursing facility

Patients presenting to the Emergency Department with signs or suspicion of infection.