Blood Culture Collection Guidelines

General Principles

• The Infectious Diseases Society of America recommends obtaining three to four blood cultures within the first 24 hours of fever onset, making every effort to draw cultures before initiating antimicrobial therapy 2, 3
• For patients without indwelling vascular catheters, the Society of Critical Care Medicine recommends obtaining at least two blood cultures from peripheral sites using separate venipunctures 2, 4
• For patients with intravascular catheters, the Society of Critical Care Medicine recommends drawing one blood culture by venipuncture and at least one through the catheter 2, 3
• The Society of Critical Care Medicine recommends drawing 20-30 mL of blood per culture to maximize yield 3, 4
• Proper skin antisepsis is recommended, with 2% chlorhexidine gluconate in 70% isopropyl alcohol being the preferred method (30 seconds drying time), or tincture of iodine (30 seconds drying time), or povidone-iodine (2 minutes drying time) 2, 4

Specific Clinical Scenarios

• The European Society of Clinical Microbiology and Infectious Diseases recommends obtaining blood cultures in patients with severe community-acquired pneumonia (PSI score IV or V or requiring ICU admission) 5
• The European Society of Clinical Microbiology and Infectious Diseases recommends obtaining blood cultures in patients with pneumonia who have risk factors for resistant pathogens 5
• The American Heart Association recommends that blood cultures are essential for patients with fever of unexplained origin and a pathological heart murmur, history of heart disease, or previous endocarditis 7

Common Pitfalls to Avoid

• The Society of Critical Care Medicine recommends against delaying antimicrobial therapy more than 45 minutes to obtain blood cultures in critically ill patients with suspected sepsis, although this specific recommendation is from Praxis Medical Insights, a similar recommendation can be found in 2
• The Society of Critical Care Medicine recommends against drawing only a single blood culture, which significantly reduces sensitivity and makes contamination difficult to interpret 2

Follow-up Blood Cultures

• The Society of Critical Care Medicine recommends that additional blood cultures should only be drawn when there is clinical suspicion of continuing or recurrent bacteremia/fungemia, or for test of cure 48-96 hours after initiating appropriate therapy 2, 4
• The Society of Critical Care Medicine recommends that additional cultures should always be paired, not single specimens 2, 3