Unveiling antibiotic resistance, clonal diversity, and biofilm formation in E. coli for safer pork production

Abstract

Abstract Escherichia coli, a commensal microorganism found in the gastrointestinal tract of human and animal hosts, plays a central role in agriculture and public health. Global demand for animal products has promoted an increase in pig farming, leading to growing concerns about the prevalence of antibiotic-resistant E. coli strains in swine populations. It should be noted that a significant portion of antibiotics deployed in swine management belong to the critically important antibiotics (CIA) class, which should be reserved for human therapeutic applications. This study aimed at characterizing the prevalence of antibiotic resistance, genetic diversity, and virulence characteristics of E. coli strains isolated in different pig farms in Portugal. Our study revealed high levels of antibiotic resistance, with resistance to tetracycline, ampicillin, tobramycin, and trimethoprim-sulfamethoxazole. Multidrug resistance is widespread, with some strains showing resistance to seven different antibiotics. The ampC gene, responsible for broad-spectrum resistance to cephalosporins and ampicillin, was widespread, as were genes associated with resistance to sulfonamide and beta-lactam antibiotics. The presence of high-risk clones, such as ST10, ST101 and ST48 are a concern due to their increased virulence and multidrug resistance. Regarding biofilm formation, it was observed that biofilm-forming capacity varied significantly across different compartments within pig farming environments. In conclusion, our study highlights the urgent need for surveillance and implementation of antibiotic management measures in the swine sector. These measures are essential to protect public health, ensure animal welfare and support the swine industry in the face of the growing global demand for animal products.