ToolsCalculators
Shapiro Rule for Blood Culture
Predicts bacteraemia to guide when to draw blood cultures.
Shapiro Rule for Blood Culture
Temperature >39.5 C (major)
Indwelling vascular catheter (major)
Clinical suspicion of endocarditis (major)
Temperature 38.3-39.4 C (minor)
Age >65 years (minor)
Chills / rigors (minor)
Vomiting (minor)
Systolic BP <90 mmHg (minor)
WBC >18,000/microL (minor)
Bands >5% (minor)
Platelets <150,000/microL (minor)
Creatinine >2.0 mg/dL (minor)
ResultLow yield
No major and fewer than two minor criteria - bacteraemia is unlikely and cultures may be deferred.
- Major criteria
- 0
- Minor criteria
- 0
When to use
- Deciding whether an adult emergency-department patient needs blood cultures.
Formula
Draw cultures if >=1 major criterion (temp >39.5 C, vascular catheter, suspected endocarditis) OR >=2 minor criteria (temp 38.3-39.4 C, age >65, chills, vomiting, SBP <90, WBC >18k, bands >5%, platelets <150k, creatinine >2.0).
Pearls and pitfalls
- A rule-out tool: high sensitivity for true bacteraemia, so a negative rule supports withholding cultures.
- Clinical judgement overrides the rule in immunocompromised or otherwise high-risk patients.