Escherichia fergusonii, an Underrated Repository for Antimicrobial Resistance in Food Animals.

A total of 1,400 samples of food animals (pigs, chickens, and ducks) were collected between July and September 2019 in China to uncover the prevalence of and its potential role in the evolution of antimicrobial resistance (AMR). An isolation of was performed and pulsed-field gel electrophoresis (PFGE) was used to uncover the genetic relationship. The AMR of isolates was comprehensively characterized using broth microdilution-based antimicrobial susceptibility testing, S1-PFGE, southern hybridization, whole-genome sequencing, and in-depth bioinformatics analysis. As a result, a total of 133 isolates were obtained. These isolates could be grouped into 41 PFGE subclades, suggesting a diverse genetic relationship. The resistance phenotypes of sulfafurazole (97.74%) and tetracycline (94.74%) were the most frequently found. Of the isolates, 51.88% were extended spectrum beta-lactamase (ESBL)-positive. Forty-three different AMR genes were revealed based on 25 genome sequences harboring Briefly, (6), (3'') and (A) genes were the most frequently observed, with the highest rate being 76.00% (19/25). Three -harboring plasmids were identified after Nanopore sequencing, including pTB31P1 (IncHI2-IncHI2A, 184,652 bp), pTB44P3 (IncI2, 62,882 bp), and pTB91P1 (IncHI2-IncHI2A, 255,882 bp). Additionally, 25 isolates harboring were clustered together with other isolates from different regions and sources available in GenBank, suggesting a possible random process of transmission in . In conclusion, is widespread in food animals in China and might be an important reservoir of AMR genes, especially and facilitate the evolution of AMR. , a member of the genus Escherichia, has been reported to transmit via the food chain and cause diseases in humans. However, the prevalence of multidrug-resistant , especially -positive isolates, has rarely been reported. Here, we collected 1,400 samples from food animals in three provinces of China and obtained 133 isolates (9.5%). We found that the prevalence of isolates was diverse, with high levels of antimicrobial resistance. Among them, 18.8% isolates carried the colistin resistance gene . Thus, may facilitate the evolution of colistin resistance as a reservoir of As far as we know, the prevalence and AMR of in the food animals in this study was first reported in China. These findings increase our understanding of the role of in public health and the evolution of antibiotic resistance.