In-vitro transfer of antibiotic resistance between faecal Escherichia coli strains isolated from pig farmers and pigs.

Faecal Escherichia coli isolated from farmers and their pigs were analyzed for biotypes, plasmid patterns and transferability of antibiotic resistance. Pairs of isolates from the farmer and pigs from the same farm with the same resistance patterns formed group A and were compared with pig and farmer isolates showing different patterns (group B). Only one pair of isolates in group A and one in group B had the same biotype. Whole plasmid patterns and plasmid profiles after restriction analysis of the paired isolates of group A showed only minimal similarities. Whereas 10/11 pig isolates in group B transferred resistance, 50% in group A did so. Transfer experiments showed similar frequencies of transfer for farmer and pig isolates in both groups. The present study does not provide conclusive evidence that there is a common pool of resistance plasmids among farmers and their pigs.