Compositions, methods, and systems for detecting methicillin-resistant Staphylococcus aureus

A method for detecting Methicillin-resistant Staphylococcus aureus (MRSA) in a sample, the method comprising:

• obtaining a whole blood sample;
• adding a selective agent to the whole blood sample, wherein the selective agent comprises an antibiotic;
• contacting the whole blood sample with a cocktail comprising one or more recombinant bacteriophages, wherein at least one of the recombinant bacteriophages comprises a genetically modified Staphylococcus aureus-specific bacteriophage genome including an indicator gene and is specific to Staphylococcus aureus, and wherein the indicator gene encodes a soluble luciferase;
• capturing the soluble luciferase with a substrate comprising an immobilized binding partner;
• washing the substrate including the captured soluble luciferase to remove any uncaptured microorganisms;
• and
• detecting a signal produced by the soluble luciferase, wherein detection of the signal is used to determine presence of MRSA in the whole blood sample, and wherein a ratio of the signal to background is at least 2.0.