The IncC and IncX1 resistance plasmids present in multi-drug resistant Escherichia coli strains isolated from poultry manure in Poland.

The study describes the whole-genome sequencing of two antibiotic-resistant representative Escherichia coli strains, isolated from poultry manure in 2020. The samples were obtained from a commercial chicken meat production facility in Poland. The antibiotic resistance profile was characterized by co-resistance to β-lactam antibiotics, aminoglycosides, and fluoroquinolones. The three identified resistance plasmids (R-plasmids), pECmdr13.2, pECmdr13.3, and pECmdr14.1, harbored various genes conferring resistance to tetracyclines (tetR[A]) for, aminoglycoside (aph, aac, and aad families), β-lactam (bla CMY-2 , bla TEM-176 ), sulfonamide (sul1, sul2), fluoroquinolone (qnrS1), and phenicol (floR). These plasmids, which have not been previously reported in Poland, were found to carry IS26 insertion elements, the intI1-integrase gene, and conjugal transfer genes, facilitating horizontal gene transfer. Plasmids pECmdr13.2 and pECmdr14.1 also possessed a mercury resistance gene operon related to transposon Tn6196; this promotes plasmid persistence even without antibiotic selection pressure due to co-selection mechanisms such as co-resistance. The chicken manure-derived plasmids belonged to the IncX1 (narrow host range) and IncC (broad host range) incompatibility groups. Similar plasmids have been identified in various environments, clinical isolates, and farm animals, including cattle, swine, and poultry. This study holds significant importance for the One Health approach, as it highlights the potential for antibiotic-resistant bacteria from livestock and food sources, particularly E. coli, to transfer through the food chain to humans and vice versa.