Whole-Genome Analysis of a Novel Multidrug-Resistant Escherichia coli Strain from Dairy Calves in Northeast China: Mechanisms of Antibiotic Resistance and Biofilm Formation

The use of antibiotics is so widespread in animal husbandry, but negligent management and lack of policies often lead to the massive use of antibiotics on farms. In this study, we collected cases of epidemic calf diarrhea in northeastern China and isolated a new strain of multidrug-resistant <i>Escherichia coli</i> (MDR-<i>E. coli</i>). In order to explore the information of this pathogen in detail, we used whole-genome sequencing to determine the genome sequence, and explored in detail the resistance, pathogenicity, genetic evolution and other biological processes of the strain through bioinformatics analysis. The results showed that the <i>E. coli</i> isolated in this study was a new multidrug-resistant strain with a large number of drug resistance genes (77) and virulence genes (84), including a circular chromosome and five circular plasmids, which are basically impossible to treat by currently commonly used antibiotics. The findings of this study suggest that the prolonged misuse of antibiotics in agricultural settings may contribute to the development of antibiotic-resistant strains of <i>E. coli</i>. This, in turn, has the potential to trigger outbreaks of antibiotic-resistant bacterial diarrhea, leading to substantial economic losses and posing significant public health risks. These results underscore the necessity for the judicious use of antibiotics and will inform the development of pertinent policies and regulations.