Evaluating facility-level variability in urinary antimicrobial susceptibility patterns in long-term care homes in Ontario, Canada.

Authors

Michelle K Wong, Nick Daneman, Bradley J Langford, Valerie Leung, Kevin L Schwartz, Sarah Swayze, Adan Amer, Thomas Braukmann, Derek R MacFadden, Kevin A Brown

Published in

Journal of clinical microbiology. Pages e0088726. Nov 11, 2026. Epub Nov 11, 2026.

Abstract

Antimicrobial resistance surveillance in long-term care homes is limited by its reliance on organism-specific summaries, most commonly Escherichia coli, which may not reflect the broader microbiological landscape in these settings. We evaluated how E. coli-based urinary susceptibility compared with weighted-incidence syndromic combination antibiograms (WISCA), a composite measure incorporating multiple pathogens, across 627 Ontario long-term care homes in 2023. Facility-level antimicrobial susceptibilities to eight antibiotics were estimated using 23,750 urinary isolates, with missing data addressed through imputation, and estimates stabilized using random-intercept logistic regression models. E. coli accounted for a mean of 50.6% (standard deviation = 1.9) of urinary isolates, with the remaining 49.5% mainly comprising Klebsiella pneumoniae (16.6% [0.8]), Proteus mirabilis (11.9% [1.2]), Enterococcus faecalis (6.6% [2.1]), and Pseudomonas aeruginosa (6.1% [0.1]). Organism-specific susceptibility varied substantially across antibiotics, particularly for ciprofloxacin susceptibility in P. mirabilis (78.7% [13.1]) and E. faecalis (48.9% [11.5]), and nitrofurantoin susceptibility in K. pneumoniae (48.5% [9.0]). Compared with E. coli-based estimates, WISCA susceptibilities were lower for seven of eight antibiotics, most notably for nitrofurantoin (WISCA: 70.6% vs E. coli: 96.8%). These findings suggest that reliance on E. coli alone may not fully capture facility-level urinary susceptibility patterns, as variation in pathogen distribution and organism-specific antibiotic susceptibilities across homes can produce substantially different susceptibility estimates. WISCA provides a more representative and stable measure by incorporating pathogen diversity and weighting organism prevalence. Integrating this into antimicrobial resistance surveillance for long-term care homes may improve the detection of emerging resistance trends and better inform antimicrobial stewardship strategies by identifying variable organism-antibiotic combinations.IMPORTANCEAntimicrobial resistance is a growing concern in long-term care homes, where infections are common, and antibiotics are frequently used. Surveillance in these settings often relies on Escherichia coli to estimate how well antibiotics will work, but this approach may not capture the range of urinary pathogens encountered in these settings, differences in resistance between organisms, or how these differences can vary across long-term care homes. In this study, E. coli represented only about half of the urinary infections, while other organisms including Klebsiella pneumoniae and Proteus mirabilis demonstrated differing susceptibility levels across antibiotics. These findings support the value of organism-inclusive surveillance, such as weighted-incidence syndromic combination antibiograms, to provide a more comprehensive picture of resistance and better inform antimicrobial stewardship strategies in long-term care homes.

PMID:
43012519
Bibliographic data and abstract were imported from PubMed on 11 Nov 2026.

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