Whole Genome Sequencing and Biological Characteristics of Two Strains of Porcine Escherichia coli Isolated from Saba Pigs.

Escherichia coli (E. coli) is an important pathogen that causes diarrhea and death in piglets. In this work, whole genome sequencing of two E. coli strains (ZB-1, ZWW-1) isolated from Saba pigs. And focus on the relationship between drug resistance, pathogenic phenotype and genotype of the two strains. This study analyzed the drug susceptibility of the two strains. The LD50 values, tissue bacterial load and intestinal pathological changes in mice infected with the two strains. The differences in gene functions such as drug resistance, virulence, and unique genes between the two strains, as well as the genetic evolutionary relationship of housekeeping genes were analyzed. The results showed that the two strains had the same resistance phenotype to most drugs. The LD50 value, tissue load, and pathological changes in mice infected with strain ZB-1 revealed that this strain was more virulent and pathogenic than strain ZWW-1. In addition, the housekeeping genes contained in the two strains are in the same large branch as E. coli of different species, and the genetic evolution is stable. All of them carry EPEC-type strain-specific virulence genes escV and ent, indicating that they are all new members of EPEC-type strains. This study laid the foundation for understanding the genetic background and biological characteristics of E. coli from Saba pigs.