Epidemiology of Gram-Negative Bloodstream Infections in the United States: Results From a Cohort of 24 Hospitals

Background: To address knowledge gaps in management of Gram-negative bloodstream infection, the Antibiotic Stewardship Implementation Collaborative was established consisting of programs from 24 academic and community hospitals across the United States.

Methods: A retrospective cohort study was conducted of unique adult patients with Gram-negative bloodstream infection hospitalized at participating hospitals from January to December 2019. Patient level and microbiologic data were collected via electronic medical record review with a standardized data collection form and data dictionary. Data analysis was largely descriptive. The Pearson χ2 test to compare categorical variables and the Wilcoxon rank sum test for continuous variables were used.

Results: In total, 4851 bacterial isolates from 3710 eligible unique patients were included in the cohort. Most common source of infection was the urinary tract (47.9%). Source control was achieved in 84% of cases. Escherichia coli (2471, 51.0%) was the most common Gram-negative organism recovered. Antibiogram combining isolates from all participating centers with species-level susceptibilities and source specific antibiograms for isolates from urinary, respiratory, and intraabdominal source were created. Northeast sites contributed the most extended spectrum beta-lactamase (ESBL) producing organisms (73%), but West sites had the highest percentage of ESBL producers of total isolates (16%). A statistically significant difference in percentage of ESBL-producing organisms in Whites vs. non-Whites (14.6 % and 9.5 %, respectively, P<0.01) was observed.

Conclusions: While the present study was conducted pre-pandemic, it highlights the need for stewardship data collaboratives to enhance our understanding of the antimicrobial resistance patterns.