The pork food chain as a root of transmission of antimicrobial resistant Escherichia coli: a farm-to-fork perspective

Background and Objectives The pork food industry contributes to the spread of antimicrobial resistant (AMR) microorganisms through the food chain and the environment.A significant risk factor is the possible development of Multi Drug Resistance (MDR) and nonsusceptibility to last generation cephalosporins.This study focuses on the pork food chain to evaluate the risk of AMR E. coli transmission from animal to consumer with a focus on cephalosporin resistance. Material and Methods Sample collection was carried out in eight fattening pig farms in North Italy from 2019 to 2022. Feces, carcasses, fresh meat and processed meat products we collected guaranteeing traceability of matrices from farm-to- fork for each animal. coli were isolated and their ability to resist to aminoglicosides, quinolones, polymixins, glycilcyclines, sulphonamides, βlactams was evaluated with a main focus on ESBL and AmpC production. Phylogenetical analyses were performed through Enterobacterial Repetitive Intergenic Consensus sequences and Average Nucleotide Identity to confirm possible relations between the strains isolated from the different production phases. Results The most frequent resistance pattern found included β-lactams-aminoglycosides-sulphonamides defining MDR strains in feces and carcasses, but not in pork meat products. The evaluation of β-lactams resistance highlights percentages ranging from 7% to 12.5% in fecal, carcass, fresh meat and processed meat product isolates in a increasing order. Data showed that the 50% of phenotypical AMR bacteria found along the pork food chain were related phylogenetically with different identity percentages.Considering β-lactamases producing strains, in only one case bacteria were closely genotypically similar from farm-to-fork (feces, carcasses, and fresh meat). Frequent close similarities were found in “carcasses and fresh meat”, “carcasses and fermented product”, “feces and fresh meat” and “fresh meat and seasoned product” isolates. Discussion and Conclusion In conclusion, direct transmission of AMR from farm-to-fork is a public health concern and β-lactams AMR transmitted in only one case. Fresh meat showed a higher risk of AMR transmission than processed meat products.However, the prudent use of antimicrobials in pig farms, the correct management of food production stages and of the environment continue to play a strategic role in the spread of AMR microorganisms.