Antimicrobial Resistance Profiles of Escherichia coli and Klebsiella pneumoniae Isolated from Cattle Farms within a One Health Framework

Antimicrobial resistance (AMR) is a major global threat to human, animal, and environmental health, particularly in livestock production systems with frequent antibiotic use. Food-producing animals can act as reservoirs for resistant bacteria, facilitating their spread through environmental pathways and the food chain. In this context, Escherichia coli and Klebsiella pneumoniae are widely used indicator organisms for monitoring antimicrobial resistance within the One Health framework.

This study aims to investigate the antimicrobial resistance profiles of Escherichia coli and Klebsiella pneumoniae isolated from cattle farms and to provide preliminary data on resistance patterns in animal and environmental samples. Sampling was conducted in four cattle farms, and 120 samples were collected, including fecal, milk, water, feed, and environmental surface samples. Following collection, samples were pre-enriched in buffered peptone water and subsequently cultured on Endo agar and chromogenic UTI agar for the selective isolation of Enterobacteriaceae. Presumptive colonies were selected based on colony morphology and subcultured to obtain pure isolates, which were identified using conventional biochemical methods.
Antimicrobial susceptibility testing was performed using the disk diffusion method in accordance with CLSI and EUCAST guidelines. The antimicrobial panel included β-lactams (ampicillin, cefotaxime, ceftazidime), fluoroquinolones (ciprofloxacin), aminoglycosides (gentamicin), tetracyclines, and sulfonamides, representing antibiotics commonly used in veterinary practice. Extended-spectrum β-lactamase (ESBL) production was evaluated using phenotypic confirmatory tests.

To date, 70 Enterobacteriaceae isolates have been obtained (62 Escherichia coli and 8 Klebsiella pneumoniae), and sampling is ongoing with an expected final collection of approximately 90 isolates. Antimicrobial susceptibility testing and ESBL screening are currently in progress, and the final analysis will focus on multidrug resistance patterns and the prevalence of ESBL-producing strains. The findings of this study are expected to provide insight into antimicrobial resistance trends in cattle farms and support the One Health approach by highlighting links between antibiotic use in livestock, environmental contamination, and public health risks.