Clinical QuickieInfectious Disease
Blood Cultures — Positive ≠ Automatically True Bacteremia
A positive bottle may represent true bloodstream infection or contamination.
Organism matters
Typical skin flora in a single bottle may be contamination; pathogens such as S. aureus or gram-negative rods carry different significance.
Number of sets matters
Growth in multiple independently collected sets makes true bacteremia more likely than one isolated positive bottle.
Time + patient context matter
Clinical syndrome, intravascular devices, immunocompromise and time-to-positivity help interpret significance.
Do not ignore true pathogens
Some organisms should trigger repeat cultures, source evaluation and complications screening rather than dismissal as contamination.
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