Hydrogen sulphide-positive strains of Escherichia coli from swine

Thirty-two H2S-positive strains of Escherichia coli, isolated from the caecal contents or mesenteric lymph nodes or both of 60 apparently healthy pigs, were characterized. Eighteen different serotypes and 18 different fermentative types were found. During conjugation with E. coli K12, four strains transferred their Hys plasmids linked to Raf, and another transferred Hys associated with the Tc determinant. All Hys-Raf plasmids belong to incompatibility group FI, whilst Tc-Hys is an Fi- plasmid.