Study objective: Although it is considered standard of care to obtain blood cultures on patients hospitalized for pneumonia, several studies have questioned the utility and cost-effectiveness of this practice. The objective of this study is to determine the impact of emergency department (ED) blood cultures on antimicrobial therapy for patients with pneumonia.
Methods: We performed a prospective, observational, cohort study of consecutive adult (age > or =18 years) patients treated at an urban university ED between February 1, 2000 and February 1, 2001. Inclusion criteria were radiographic evidence of pneumonia, clinical evidence of pneumonia, and blood culture obtained. Blood cultures were classified as positive, negative, or contaminant based on previously established criteria. Additionally, data were collected on antimicrobial sensitivities, empiric antibiotic therapy, antibiotic changes, and reasons for changes.
Results: There were 3,926 ED visits with blood cultures obtained for any reason, of which 3,762 (96%) were available for review. Of these, 414 of 3,762 (11%) patients met pneumonia study inclusion criteria, and blood cultures identified 29 of 414 (7.0%) patients with true bacteremia. In the 414 patients, blood culture results altered therapy for 15 patients (3.6%) with suspected pneumonia, of which 11 (2.7%) patients had their coverage narrowed; only 4 (1.0%) patients had their coverage broadened because of resistance to empiric therapy. For the 11 patients with bacteremia whose therapy was not altered, culture results actually supported narrowing therapy in 8 (1.9%) cases, but this was not done.
Conclusion: Blood cultures rarely altered therapy for patients presenting to the ED with pneumonia. More discriminatory blood culture use may potentially reduce resource utilization.