Methods: The SPD is a sterile blood collection system that diverts 1-2mL of the initial venipuncture blood into an isolated diversion chamber and then allows pure venous blood to flow into culture bottles. SPD was prospectively used to randomly collect 1 of the 2 paired culture sets from each patient. Culture was performed on diverted blood by injecting 0.5 mL Tryptic Soy Broth (TSB) into the diversion chamber and mixing it with the blood. The blood/TSB mixture was incubated for 24 hours then plated to Blood Agar. Agar plates were incubated at 35 °C and examined for 4-5 days before finalizing as negative. Identification of any isolate was performed according to standard microbiology procedures.
Results: 108 SPD blood samples were cultured and analyzed. 2 patients were SPD diversion blood positive with coagulase negative staphylococci and routine blood culture negative, for an avoided contamination rate = 1.9% (95% CI: 0.5%-6.5%). Additionally, 2 patients were SPD diversion blood and routine blood culture positive with the same pathogen, and 5 patients were SPD diverted blood negative but routine blood culture positive with a pathogen (giving an expected frequency of bacteremia detection <50% when only 1-2mL diverted blood is cultured).
Conclusion: Our results demonstrate that diversion of the first 1-2 mL of blood can help to lower the blood contamination rate by capturing likely skin contaminants. Assessment of SPD should approach clinical trials with the hypothesis that very low rates of contamination are achievable using diversion devices.
R. Thomson Jr., None
L. Peterson, Magnolia: Board Member , Consulting fee and Research grant