Exploring variability in antibiograms: a cross-sectional study

Background: Antibiograms are important tools for guiding empirical antimicrobial prescribing and monitoring antimicrobial resistance (AMR); however, there are challenges to their implementation and interpretation in practice. Variable formatting may be a contributing factor. This study explores variability in antibiogram data presentation to identify opportunities for improvement. Methods: Antibiograms from hospitals in Ontario were evaluated by visual inspection for general formatting and style, organism-specific data presentation and stratification based on CLSI M39 guidelines (Fifth Edition, 2022) and relevant literature. Hospitals were categorized by type and descriptive analysis was performed. Results: Forty-three antibiograms from 60 hospitals were included: 33.3% were large community; 26.7% were academic teaching; 20% were small community; 11.7% were medium community; and 8.5% were complex continuing care/rehabilitation facilities. All antibiograms reported at least 1 year of data, with 26.5% aggregating data from multiple facilities. Most either reported on organisms with at least 30 isolates (23.2%) or included a statement about interpretation of small numbers (69.8%). Only 27.9% included a statement about exclusion of duplicates, and 18.6% included guidance on how to use the antibiogram. Data were reported separately for Staphylococcus aureus, MRSA and MSSA in 39.5% of antibiograms. Almost half of antibiograms incorporated at least one method of stratification; specimen source was most common (39.5%); and 18.6% (n = 8) included a weighted-incidence syndromic combination antibiogram (WISCA). Conclusions: There is significant variability in antibiogram data presentation across Ontario hospitals. Additional format standardization may help improve use for clinical decision-making and monitoring of AMR trends.