[Blood cultures in the emergency department]

Abstract

Introduction: Culture of emergency room blood samples is common practice, but open to controversy. As compared to other emergency tests, blood collection requires twice as much time and needs a refined technique to avoid contamination, and the study has no immediate diagnostic utility.

Methods: This prospective study includes consecutive adult patients with positive emergency room blood cultures. We analyzed the diagnostic sensitivity and contamination rate of the cultures and the etiology, clinical features and prognosis of the bacteremias encountered.

Results: During the study period, 5.2 blood cultures were indicated per 1000 patients attended in the emergency room. The diagnostic yield (positive blood cultures/total cultures) was 20% and the contamination rate (contaminated blood cultures/total cultures) was 1%. The incidence of bacteriemia was 0.99 episodes per 1000 patients attended in the emergency room and 10.3 episode per 1000 hospitalized patients. Gram-negative bacteria predominated (57%). Sepsis was the most frequent clinical manifestation (50%), followed by severe sepsis (40%) and septic shock (10%). Mortality was 22%. Diabetes mellitus and severe sepsis/septic shock were independent factors associated with mortality.

Conclusions: Diagnostic performance and quality of emergency room blood cultures was high. The predominant etiology was gram-negative bacteria. Patients had a severe clinical presentation. Diabetes mellitus and severe sepsis and/or septic shock were independent prognostic factors of mortality.