Blood culture

When to request this test

This test is used to identify the presence of bacteria in blood, and allows for diagnosis of bloodstream infections.

It can be prescribed during:

• Fever 
• Suspicion of endocarditis 

Requirements:

• Prescription before any antibiotherapy
• Don’t wait the results and start an empiric antibiotherapy if necessary (sepsis, septic shock)
• Fever and nore argument for a viral infection
• Clinical argument for bacteriological infection, before antibiotic prescription
• Sepsis: infection and any signs of severity (vital signs)
• Nosocomial low blood pressure of unknown origin

Interferences & limitations

• Contamination by skin flora during sampling: follow careful aseptic sampling procedure
• Insufficient volume (lack of test sensitivity: risk of missing bacteremia)
• Prior antibiotic therapy can inhibit the growth of bacteria, leading to false-negative results.

It is recommended to stop antibiotics before sample collection, if possible.