Diagnosing bacteremia at a Danish hospital using one early large blood volume for culture.

The objective of the study was to evaluate the yield of a blood culture based on inoculating 40 ml of blood drawn from 1 venipuncture. During a 3-year period (1990-1992) 1351 (19.3%) of 6994 blood culture sets were positive. The increased yield of true bacteremic events using 40 ml instead of 30 ml of blood per blood culture was estimated to be 4.2%. Contaminants were isolated in 5% of the blood culture sets, with coagulase negative staphylococci being the most frequently isolated contaminants (3.2%, 1.3% of the culture bottles). In most of cases, contaminants were only isolated in 1 or 2 of the 4 bottles of the set. Furthermore, a positive correlation was observed between the number of positive culture bottles and the recovery of a clinically-significant microorganism. Neither the frequency nor the interpretations of positive blood culture events with microorganisms of questionable significance were major obstacles. In conclusion, the spectrum and yield of microorganisms drawing 40 ml of blood from one venipuncture into 4 culture bottles was satisfactory. The method bears obvious advantages from a clinical point of view, since usually only 1 venipuncture is needed before institution of antibiotic treatment.