No Clear Differences between Organic or Conventional Pig Farms in the Genetic Diversity or Virulence of Isolates.

To evaluate the impact of pig farm management on the genetic diversity and on the virulence of , we characterized isolates from 19 organic pig farms (62 isolates) and from 24 conventional pig farms (58 isolates). The 120 isolates were typed using pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and the presence of nine virulence genes was screened using real-time PCR. The capacity of adhesion and invasion of 61 isolates (32 from organic and 29 from conventional farms) were then tested on human intestinal cells.