Authors: Elias Leta, Gillis David C, Gurrola-Rodriguez Tanya, Jeon Jeong Ho, Lee Jung Hun, Kim Tae Yeong, Lee Sang Hee, Murray Sarah A, Ohta Naomi, Scott Harvey Morgan, Wu Jing, Rogovskyy Artem S
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Over a five-year period, researchers isolated *Escherichia coli* from clinical cases at Texas A&M's veterinary teaching hospital to investigate the prevalence and genetic basis of antibiotic resistance, particularly focusing on extended-spectrum beta-lactamase (ESBL) activity as a marker of multidrug resistance. Of 48 ceftiofur-resistant isolates, 27% tested positive for ESBL phenotype, and molecular characterisation identified CTX-M-1 and SHV genes alongside TEM-1, AmpC and OXA-type beta-lactamases; notably, a novel TEM-1 variant (*blaTEM-233*) and the first documented equine case of *E. coli* ST1308 (previously reported only in other herbivores) harbouring an SHV-type ESBL gene were discovered. Concerning additional findings included detection of the carbapenemase gene *blaIMP-1* in one isolate, albeit without phenotypically confirmed carbapenem resistance. These results highlight the concerning potential for horses to serve as reservoirs and vectors for ESBL-producing pathogens, with implications for both equine clinical outcomes and broader antimicrobial stewardship, warranting systematic surveillance of antibiotic resistance patterns in equine populations and careful consideration of empirical antimicrobial selection in cases of suspected bacterial infection.
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Practical Takeaways
- •ESBL-producing E. coli is present in equine clinical infections and may warrant antimicrobial susceptibility testing to guide appropriate therapeutic choices
- •Equine patients should be considered potential reservoirs for multi-drug resistant pathogens, with implications for biosecurity and treatment protocols
- •Ceftiofur resistance alone may not reliably predict ESBL phenotype in equine E. coli, suggesting need for confirmatory testing in clinical practice
Key Findings
- •27.08% (n=13) of 48 ceftiofur-resistant E. coli isolates from equine clinical specimens were phenotypically ESBL-positive
- •CTX-M-1 and SHV ESBL genes were detected in 7 of 13 ESBL-positive isolates, with identification of a novel blaTEM-233 variant
- •E. coli ST1308 was identified in horses for the first time, harboring SHV-type ESBL genes
- •One isolate was PCR-positive for carbapenemase gene blaIMP-1 without phenotypic imipenem resistance