Phenotypic and Genotypic Characterization of Escherichia coli and Salmonella spp. Isolates from Pigs at Slaughterhouse and from Commercial Pork Meat in Portugal

<b>Background:</b> Foodborne diseases are a serious public health concern, and food-producing animals are a major source of contamination. <b>Methods:</b> The present study analysed <i>Escherichia coli</i> and <i>Salmonella</i> spp. isolated from faecal samples of 100 fattening pigs and from 52 samples of pork meat. <b>Results:</b> The results showed that the majority of the analysed meat samples were considered satisfactory in terms of microbiological quality (92.3% for <i>E. coli</i> and 94.2% for <i>Salmonella</i> spp.). <i>Salmonella</i> spp. was identified in 5.8% of the meat samples, whereas <i>E. coli</i> was detected in 89.5% of all samples (69.2% in meat and 100% in faecal samples). Furthermore, 1.9% of the faecal samples contained Shiga-toxin-producing <i>E. coli</i> and 3.9% contained enterotoxigenic <i>E. coli</i>. All sequenced isolates presented virulence genes for extraintestinal pathogenic <i>E. coli</i>. Moreover, 75.0% of <i>E. coli</i> isolates from meat and 71.8% from faeces samples showed antibiotic resistance, with 40.7% and 51.4%, respectively, being multidrug-resistant (MDR). The most prevalent resistances were to tetracycline, ampicillin, and sulfamethoxazole, and one <i>E. coli</i> isolate showed resistance to extended-spectrum β-lactamase. <b>Conclusions:</b> This study highlights the role of pigs as a potential source of human contamination and the importance of a One Health approach to ensure food safety and to promote public health.