Sessions

Antimicrobial resistance (AMR) is one of the most severe health challenges of our time, in which industrial animal farming plays a major role. Antibiotics used in intensive animal farming exert a strong selection pressure on bacteria, leading to the spread of strains resistant to the given agents, thus posing a direct public health risk based on the One Health framework. The aim of this research was to provide a comprehensive, quantitative evaluation of the antimicrobial susceptibility of Escherichia coli strains isolated from large-scale pig farms in the Northern Great Plain region. By examining resistance profiles, multidrug resistance (MDR) patterns, as well as the distribution of resistance among age groups and its epidemiological correlations, it provides a more comprehensive picture for understanding the problem.During the laboratory work, a total of 151 E. coli isolates from 3 pig farms in the Northern Great Plain region were examined, originating from day-old, as well as 4-, 5-, and 6-week-old animals. Antimicrobial susceptibility was determined using the standard broth microdilution method by measuring minimum inhibitory concentrations (MIC). Resistance rates were calculated by antimicrobial agent and by age group. For data evaluation, network analysis, hierarchical clustering, and Jaccard distance-based principal coordinates analysis (PCoA) were applied; false discovery rates were controlled using the Benjamini-Hochberg correction. The highest resistance rates were measured against amoxicillin (78.8%), potentiated sulfonamide (50.3%), neomycin (45.7%), and gentamicin (39.1%). Of the examined strains, 62.9% met the MDR criteria. By comparing cefotaxime and cefotaxime-clavulanic acid MIC values, 26.5% of the isolates showed a phenotype suspected of extended-spectrum ß-lactamase (ESBL) production. Significant differences were identified between age groups for several antimicrobial agents.

Overall, it can be concluded that E. coli populations on pig farms exhibit a significant phenotypic resistance burden, with a frequent occurrence of multidrug resistance, thereby confirming that the swine sector plays a key role in the global ecology of antimicrobial resistance. Age-group-specific differences indicate that the most critical point for interventions is early age, and that managing the situation requires integrated, One Health-oriented monitoring, as well as the development of biosecurity measures.