Would earlier microbe identification alter antibiotic therapy in bacteremic emergency department patients?

Background: Although debate exists about the treatment of sepsis, few disagree about the benefits of early, appropriately targeted antibiotic administration.

Study Objectives: To determine the appropriateness of empiric antimicrobial therapy and the extent to which therapy would be altered if the causative organism for sepsis was known at the time of administration.

Methods: This was a retrospective cohort study, conducted in an academic Emergency Department (ED), on consecutive positive blood cultures between November 1, 2008 and February 1, 2009. Blood cultures and the appropriateness of administered antimicrobial therapy were evaluated. Therapy choices were categorized based on whether or not a physician, complying with antimicrobial guidelines, would have made changes to empiric antibiotic therapy had the causative organism initially been known.

Results: There were 90 positive blood cultures obtained from 84 patients. Of these, 21.1% (n=19) were considered contaminants. The final categorization of empiric antibiotics given in the ED for the remaining blood culture results were: 1) therapy would be changed to narrower-spectrum antibiotics (n=34, 55.7%); 2) therapy would be changed because the organism was not covered (n=13, 21.3%); and 3) therapy would remain the same (n=14, 23.0%). There was 90.2% inter-rater agreement for these classifications (p<0.0001), with a kappa of 0.84. Polymerase chain reaction analysis had a statistically significant advantage (p<0.0001) over Infectious Disease Society of America protocols in facilitating accurate antimicrobial therapies.

Conclusion: This study confirms the need for more rapid and accurate laboratory methods for bloodstream pathogen identification.