Duration of Antimicrobial Treatment for Bacteremia in Canadian Critically Ill Patients∗

Objectives: The optimum duration of antimicrobial treatment for patients with bacteremia is unknown. Our objectives were to determine duration of antimicrobial treatment provided to patients who have bacteremia in ICUs, to assess pathogen/patient factors related to treatment duration, and to assess the relationship between treatment duration and survival. Design: Retrospective cohort study. Settings: Fourteen ICUs across Canada. Patients: Patients with bacteremia and were present in the ICU at the time culture reported positive. Interventions: Duration of antimicrobial treatment for patients who had bacteremia in ICU. Measurements and Main Results: Among 1,202 ICU patients with bacteremia, the median duration of treatment was 14 days, but with wide variability (interquartile range, 9-17.5). Most patient characteristics were not associated with treatment duration. Coagulase-negative staphylococci were the only pathogens associated with shorter treatment (odds ratio, 2.82; 95% CI, 1.51-5.26). The urinary tract was the only source of infection associated with a trend toward lower likelihood of shorter treatment (odds ratio, 0.67; 95% CI, 0.42-1.08); an unknown source of infection was associated with a greater likelihood of shorter treatment (odds ratio, 2.14; 95% CI, 1.17-3.91). The association of treatment duration and survival was unstable when analyzed based on timing of death. Conclusions: Critically ill patients who have bacteremia typically receive long courses of antimicrobials. Most patient/pathogen characteristics are not associated with treatment duration; survivor bias precludes a valid assessment of the association between treatment duration and survival. A definitive randomized controlled trial is needed to compare shorter versus longer antimicrobial treatment in patients who have bacteremia.