Detection of virulence genes of Escherichia coli strains isolated from piglets with diarrhea in north Guangdong and preliminary study on their pathogenicity

Enterotoxin virulence-related gene（ STa，STb and LT） and HPI gene（ irp2） of 56 strains of Escherichia coli isolated from piglets with diarrhea were detected by corresponding PCR，and part of strains were chosen according to virulence factors gene-type for animal pathogenicity test. The results showed that 38 strains had virulence genes，the positive rates of STa，STb，LT and irp2 genes respectively were 3.57%，53.57%， 7.14% and 21.43%. There were 5 virulence factors genotypes，the major genotypes were STb and STb+irp2. The pathogenicity test showed that positive strains had pathogenicity to mice. In north Guangdong，the major virulence factors of pathogenic E. coli from diarrhea piglets were STa and irp2，a few strains carried STa and LT， some isolates expressed two virulence factors. Detection of virulence genes was an important reference for rapid determining pathogenicity of E. coli.