Bloodstream Infections and Infective Endocarditis

The answer first

A positive blood culture is not a result — it is a decision. Three rules carry most of the DWE marks and most of the ward safety ^[6]:

1. Cultures before antibiotics, always. Three sets from separate venepuncture sites, with adequate volume, drawn before the first dose whenever the clinical situation allows even a few minutes. Every dose of antibiotic given before cultures erodes the diagnostic yield you will be arguing about for the next fortnight ^[4].
2. S. aureus in the blood is never a contaminant and never minor. It demands repeat cultures to document clearance, an echocardiogram in most patients, an infectious diseases consult, and a hunt for metastatic foci — and it is never short-coursed until endocarditis and seeding have been excluded ^{[6] [7]}.
3. Endocarditis is diagnosed by criteria and treated for weeks, not days. Apply the modified Duke criteria explicitly, image early (TTE, then TOE when there is a prosthetic valve, a device or high suspicion), give organism-directed intravenous therapy for four to six weeks, and know the three surgical triggers — heart failure, uncontrolled infection, and prevention of embolism ^{[1] [2]}.

A note on scope: this topic owns the infectious-diseases framing — bloodstream infection, cultures, source control, antimicrobial strategy and duration. The structural valve detail and surgical technique of endocarditis live in the cardiovascular infective endocarditis topic; the two are designed to be read together ^[2].

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References24ShowHide

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