Mobile genetic elements associated to antibiotic resistance in Salmonella enterica isolates collected in food-chain

In this study, we assessed the presence of IS26 elements in 60 multidrug resistant (R-type ASSuT phenotype) Salmonella enterica isolates collected in slaughtered swine samples in Portugal, investigating its role in the dissemination of antimicrobial resistance among different reservoirs. PCR-mapping allowed us to describe a new genetic organization, in the emergent Salmonella Rissen, including a peptidase C14 caspase catalytic subunit P20 gene between two IS26 elements. Furthermore, we detected the same genetic structures in Salmonella isolates from different serotypes in samples from slaughtered swine, carcasses/meat, and meat handlers, namely a resistance region harboring blaTEM-1 genes also flanked by 2 copies of IS26 elements in Salmonella Typhimurium (n=17) and Salmonella 4,[5],12:i:- variants (n=2). This study highlights that IS26 mobile genetic elements might play an important role in the mobilization of antibiotic resistance genes, which can constitutes a problem in terms of veterinary medicine and public health in general.