The purpose of this study is to see if, in selected patients with a serious bacterial infection of the bloodstream, treating the bacterial infection with a combination of antibiotics is more effective than treating the infection with a single antibiotic. Participants must have blood cultures which are positive for a certain type of bacteria.

Staphyloccocus aureus bacteremia (SAB) is a common infectious disease condition in hospitalized patients which is associated with significant morbidity, excessive costs, and high mortality, despite effective antibiotic therapy. This pragmatic study is designed to test the hypothesis that outcomes in adults hospitalized with SAB will be improved by using combination antibiotic therapy (CAT) as early, targeted therapy in a high-risk subgroup. A group of patients identified early in their course as meeting at least one high-risk criterion who have no contraindications will be treated with one of two antibiotic strategies commonly used within usual care, namely: 1) antibiotic monotherapy or 2) combination antibiotic therapy, depending on the random assignment for each hospital, each month. Low-risk patients will be treated per usual care. Data from all patients admitted to participating hospitals with SAB will be included in the analysis.

Inclusion Criteria:

• Age ≥18 years

• Alive and admitted to an Intermountain Health (IH) hospital acute care unit at enrollment

• Initial positive blood culture with either methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-susceptible Staphylococcus aureus (MSSA), collected:

  1. on or during the index admission to an IH hospital, or

  2. in an ambulatory setting (laboratory, clinic or emergency department) within 48 hours of the index admission, or

  3. at a non-IH network hospital within 24 hours of subsequent transfer to an IH hospital

     Exclusion Criteria:

• Patient requests that patient health data not be included in the analysis

In order to protect patient privacy and comply with relevant regulations, identified data will be unavailable. Requests for deidentified data from qualified researchers with appropriate ethics board approvals and relevant data use agreements will be processed by the Intermountain Office of Research, officeofresearch@imail.org

Data sharing will be available six months after anticipated enrollment completion, estimated August 2029, for a period to be determined by the Intermountain Office of Research and IRB

Will be determined on an individual basis, upon request to the IH Office of Research.