Escherichia coli and Antibiotic Resistance in Swine Farming: Implications for Public Health

In swine farming, E. coli plays a critical role in transmitting multi-drug resistance (MDR). Antibiotic use in swine management promotes antibiotic-resistant bacteria emergence, limiting treatment options and spread through food-chain. The aim of this study is investigating the role of E. coli, focusing on MDR, genotypic analysis, Multi-Locus Sequence Typing (MLST), and phylogenetic analysis from different pig farms.

Fifty-nine swine fecal samples were obtained from 12 pig farms, yielding 47 E. coli isolates. Of these, 44 were from breeding pigs, distributed as different compartments. Eight samples from fattening pigs yielded two E. coli strains. Antibiotic resistance was observed in all 46 E. coli isolates tested, with high resistance to tetracycline (100%), ampicillin (97.8%), tobramycin (97.8%), and trimethoprim-sulfamethoxazole (95.7%). MDR was common, with 9 isolates resistant to four antibiotic classes, 18 to five, 13 to six, and 6 to seven classes. In genotypic analysis, ampC gene was predominant (86.95%), followed by blaTEM (60.86%), sul3 (60.86%). For MLST, we selected 7 strains resulting in the identification of 6 STs: ST101, ST5229, ST48, ST5757, ST10, and ST1147. Phylogroup A dominated at 60.8%, followed by B1 at 30.4%, and D at 8.69%.

High rates of resistance were observed and MDR was widespread, with resistant to multiple antibiotic classes. Overall, this study highlights the urgent need for surveillance and intervention strategies to mitigate the transmission of antibiotic-resistant E. coli from swine to humans, protecting both animal and public health in the context of swine farming practices.