Appropriateness of blood culture: A comparison of practices between the emergency department and general wards.

Background: The decision to perform a blood culture is influenced by factors, such as the pretest probability of bacteremia, resource availability and individual clinician's preference. The lack of formal guidelines results in inconsistencies in practices and an inappropriate or overuse of blood cultures. The primary aim of this study is to compare the rate of positive blood cultures in the emergency department (ED) and general ward. The secondary aim of this study is to analyze factors associated with a positive blood culture.

Methods: We compared 200 consecutive patients in the ED with 200 consecutive patients with first blood cultures done within 24 h of admission from ED to the general ward. We analyzed the clinical characteristics, proportion of positive blood cultures, and variables associated with a positive blood culture.

Results: The percentage of positive blood cultures was 13.5% (n = 27) in the ED group, compared with 6.0% (n = 12) in the general ward group. Contamination rates were higher in the ED compared to general ward (4% vs 0.5%). Heart rate and rigors were independently associated with a positive blood culture in a multivariate logistic regression model.

Conclusion: There was a lower rate of positive blood cultures in the general ward group. Reasons may include a lower threshold for performing blood cultures in the general ward, and prior antibiotics in the ED reducing the sensitivity of blood cultures taken in the general ward. Adherence to clinical decision rules and education of junior staff are needed to improve the efficiency of blood culture taking practices.