Exploring variability in antibiograms: a cross-sectional study

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.

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.

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).

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.