The purpose of this study is to evaluate overall changes in patient management and longer-term resource utilization between control and test arms, including (but not limited to) additional work-up (including other diagnostic tests and consults), antimicrobial treatments, disposition decisions and hospital length of stay (LOS)

The trial seeks to compare the benefits of adding a diagnostic test that can distinguish the etiology of an acute respiratory illness early in the work-up and management. All adult patients shall be evaluated through the Emergency Department (ED) as an undiagnosed acute reparatory illness (URI). The included patient cohort must present with SIRS criteria and be ill enough to require immediate blood draw and management by the ED. Excluded are any URIs with a predetermined diagnosis or subjects presenting with illness not determined to be a URI as a primary diagnosis. The experimental arm of the study shall have in addition to the standard of care labs and diagnostics, a novel protein array blood test that can distinguish bacterial from viral disease. The control group will not receive these results. The trial seeks to examine the difference in clinical outcomes when a adjunct biomarker than can help the clinician guide more accurate therapy is available early in the diagnostic workup. Benefits are defined in the primary and secondary outcomes as reduced resources expended through reduced laboratory, radiological, blood bank, and pharmaceutical expenditures. Comparative resource utilization costs include changes in hospital and or ED length of stay, lower follow up visits and readmissions, less inpatient and outpatient physician consultants and services called for to manage the patients care, and overall costs. Both primary and secondary outcomes will be used to categorize the costs and resources required to manage the patient. Primary objective is to evaluate overall changes in patient management and longer-term resource utilization between control and test arms, including (but not limited to) additional work-up (including other diagnostic tests and consults), antimicrobial treatments, disposition decisions and hospital length of stay (LOS). The exploratory objective is to evaluate changes between control and test arm in ED LOS, bounce backs (patients returning within 72 hours), work-up costs and the impact of physician seniority.

Inclusion Criteria for main study population :

• Current disease duration ≤ 7 days
• Temperature ≥ 37.8°C (100°F) or tactile fever, noted at least once within the last 7 days
• Clinical suspicion of bacterial or viral respiratory tract infection (RTI)

Exclusion Criteria for main study population:

• Systemic antibiotics taken up to 48 hours prior to presentation
• Outpatient steroids taken within 48 hours prior to presentation
• Suspicion and/or confirmed diagnosis of infectious gastroenteritis/colitis
• Inflammatory disease
• Congenital immune deficiency (CID)
• A proven or suspected infection on the presentation with Mycobacterial, parasitic or fungal (e.g., Candida, Histoplasma, Aspergillus) pathogen
• Human immunodeficiency virus(HIV), Hepatitis B Virus (HBV), or Hepatitis C Virus (HCV) infection (self-declared or known from medical records)
• Major trauma and/or burns in the last 7 days
• Major surgery in the last 7 days
• Pregnancy - Self reported or medically confirmed
• Active malignancy - Cancer diagnosed within the previous six months, recurrent, regionally advanced, or metastatic cancer, cancer for which treatment had been administered within six months, or hematological cancer that is not in complete remission.
• Current treatment with immune-suppressive or immune-modulating therapies, at some point in the past 10 days
• Hemodynamically unstable (require life-saving interventions such as vasopressors)
• Patients transferred from another facility who already have a differentiated respiratory illness (known diagnosis e.g., culture positive results)
• Consider unsuitable for the study by the study team

Inclusion Criteria for Subgroup:

• Written informed consent must be obtained from the patient or his/her legal guardian
• Current disease duration ≤ 7 days
• Clinical suspicion of bacterial or viral sepsis based on 2 or more SIRS criteria OR Clinical suspicion of bacterial or viral respiratory tract infection (RTI) AND temperature ≥ 37.8°C (100°F) or tactile fever, noted at least once within the last 7 days

Patients fulfilling one or more of the following exclusion criteria from the main group are eligible for the subgroup cohort:

• Systemic antibiotics taken up to 48 hours prior to presentation
• Outpatient steroids taken within 48 hours prior to presentation
• Suspicion and/or confirmed diagnosis of infectious gastroenteritis/colitis
• Inflammatory disease (e.g., IBD, SLE, RA, other vasculitis)
• Congenital immune deficiency (CID)
• A proven or suspected infection on the presentation with Mycobacterial (e.g., MAC, MABC), parasitic or fungal (e.g., Candida, Histoplasma, Aspergillus) pathogen
• HIV, HBV, or HCV infection (self-declared or known from medical records)
• Major trauma and/or burns in the last 7 days
• Major surgery in the last 7 days
• Pregnancy - Self reported or medically confirmed
• Active malignancy of a solid tumor - Cancer diagnosed within the previous six months, recurrent, regionally advanced, or metastatic cancer, cancer for which treatment had been administered within six months, or hematological cancer that is not in complete remission
• Current treatment with immune-suppressive or immune-modulating therapies, at some point in the past 10 days
• Hemodynamically unstable (require life-saving interventions such as vasopressors)
• Patients transferred from another facility who already have a differentiated respiratory illness (known diagnosis e.g., culture positive results)

Statistician assessing financial and resource utilization between study arms (primary and secondary outcomes) will be blinded as to which cohort had the results of the Memed diagnostic test (experimental vs standard groups)