# P-579. Comparison of Extended Spectrum Beta-Lactamase Producing Escherichia coli Clonotypes Colonizing and Infecting Humans, Dogs and Cattle in Wisconsin Reveals Greatest Similarity Between Humans and Dogs

## TL;DR

This study compares antibiotic-resistant E. coli strains in humans, dogs, and cattle in Wisconsin, finding closer genetic similarity between human and dog strains than with cattle.

## Contribution

A novel clonotyping method reveals greater similarity between human and dog E. coli strains compared to cattle.

## Key findings

- Human and dog E. coli clonotypes show strong correlation (R²=0.924, 0.903).
- Cattle E. coli clonotypes correlate poorly with those from humans and dogs.
- Wisconsin human clonotypes align closely with a national dataset (R²=0.977, 0.966).

## Abstract

Mitigation of antimicrobial resistance in human and veterinary medicine relies on diagnostics, surveillance, and stewardship. Previously, we reported the prevalence of third-generation cephem-resistant (3GCR) Escherichia coli colonizing humans (3.7%), dogs (13.1%), and cattle (51.5%) in our service area (Ortiz 2022). Here, we present new data using a novel clonotyping method to characterize clonal composition of 3GCR E. coli among these hosts.

Previously collected 3GCR E. coli isolates colonizing or infecting humans and dogs, and colonizing cattle in Wisconsin, were analyzed. Clonotyping was performed using a rapid method that detects 7 single nucleotide polymorphisms within two genes (fumC and fimH), yielding results comparable to multilocus sequence typing (Tchesnokova 2016). Only major clonotypes, comprising ≥2% of isolates per host, were included. Clonotype 561, corresponding to the pandemic multidrug-resistant ST131-H30 subclone, was excluded to avoid biasing the human clonal composition. Linear regression was used to compare clonotypes' composition and abundance between host species, and with a national dataset of 474 uropathogenic 3GCR E. coli isolates from humans (courtesy of Prof. E. Sokurenko). Comparisons were made by host species, and by source (Wisconsin vs. national).

A total of 447 Wisconsin 3GCR isolates were analyzed (human n=220; dog n=140; cattle n=87). Linear regression analysis showed a strong correlation between human and dog clonotypes, and vice versa (R²=0.924, 0.903). Human and dog clonotypes correlated poorly with cattle clonotypes (R²=0.268, 0.353), and cattle clonotypes correlated poorly with those from humans and dogs (R²=0.365, 0.301). Wisconsin human clonotypes correlated strongly with the national human dataset (including clonotype 561; R²=0.977, 0.966). Dogs showed moderate correlation (R²=0.701, 0.674), whereas cattle correlated poorly with the national dataset (R²=0.208, 0.260).

While cattle harbor a larger reservoir of transferable resistance genes, the clonal composition of 3GCR E. coli in this collection shows significantly greater similarity between humans and dogs than between humans and cattle, or between dogs and cattle.

Joshua Petrie, PhD, CSL Seqirus: Advisor/Consultant|CSL Seqirus: Grant/Research Support|ModernaTX: Grant/Research Support