Blood Culture Collection Temperature Guidelines
Blood cultures should be drawn at normal body temperature (37°C) and immediately transported to the laboratory for incubation, not at a specific patient temperature threshold. The focus should be on proper collection technique rather than patient temperature when obtaining blood cultures.
Indications for Blood Culture Collection
- Blood cultures should be obtained before initiating antimicrobial therapy in patients with suspected infection, as long as collection doesn't delay treatment by more than 45 minutes 1
- At least two sets of blood cultures (aerobic and anaerobic) should be collected before starting any new antimicrobial therapy 1
- Blood cultures are not indicated based solely on isolated fever or leukocytosis without considering the pretest probability of bacteremia 2
Proper Collection Technique
- Use proper skin antisepsis with 70% isopropyl alcohol or iodine solution, cleaning twice before venipuncture 1
- Obtain adequate blood volume (20-60 ml total) for optimal detection of bacteremia 1, 3, 4
- For adults, each blood culture bottle should contain 10-30 ml of blood 1, 4
- Inadequate blood volume significantly reduces detection rates - studies show standard volume cultures (mean 8.7 ml) detect 92% of bloodstream infections compared to only 69% with low volume (mean 2.7 ml) 3
- Increasing cultured blood volume from 20 to 40 ml increases yield by 19%, and from 40 to 60 ml increases yield by an additional 10% 4
Timing Considerations
- Blood cultures should be obtained as soon as possible after onset of fever or chills 1
- The yield of blood cultures does not improve with sequential or temperature-synchronized collections 1
- Immediate incubation of blood cultures at 37°C (not patient temperature) reduces time to reporting of results by approximately 15 hours 5
Special Considerations
- For patients with intravascular catheters in place >48 hours with suspected catheter-related infection, obtain at least one set of blood cultures from the catheter along with peripheral blood cultures 1
- For patients without suspected catheter-related infection, at least one blood culture should be obtained peripherally 1
Common Pitfalls to Avoid
- Delaying antimicrobial administration beyond 45 minutes to obtain blood cultures, as each hour of delay increases mortality 1
- Using improper aseptic technique, which increases contamination rates and false positives 1
- Collecting inadequate blood volume, which significantly reduces detection rates 3, 4
- Using pediatric collection tubes for adult patients, which results in insufficient volume 3