Blood cultures and bacteraemia in an Australian emergency department: Evaluating a predictive rule to guide collection and their clinical impact.

OBJECTIVE

The objective of the present study is to determine whether a predictive rule could safely reduce the number of negative blood cultures collected in an Australian ED and to assess the clinical impact of positive results from blood cultures taken in the ED.

METHODS

All positive blood cultures taken in the ED at a single facility were retrospectively identified for the calendar year 2012. Clinically significant bacteraemia episodes were assessed against a predictive rule using major and minor clinical and laboratory criteria gathered from medical records and pathology databases, and compared with a randomly generated sample of ED patient episode with negative blood cultures. The ED and final diagnoses and blood culture impact on clinical management were also collected.

RESULTS

The predictive rule has a high sensitivity (98.8%) and modest specificity (48.7%), and if applied stringently would have prevented almost half of all blood cultures in our ED but missed two positives. Blood cultures altered the clinical management of 94.3% bacteraemic patients, representing 3.4% of all ED patients with blood cultures performed. High discordance (54%) between ED diagnosis and discharge diagnosis of bacteraemic patients was noted.

CONCLUSIONS

Bacteraemia detected in the ED alters subsequent patient management. The predictive rule can be safely applied in the ED to determine need for blood culture collection. Blood cultures should not be omitted in the ED based entirely on preliminary diagnosis given the high discordance seen between ED and discharge diagnosis.