R plasmids in Salmonella typhimurium in the United Kingdom.

In the United Kingdom, R plasmids are common in bovine-associated phage types of Salmonella typhimurium and in particular in strains of phage type 204c (DT204c); all strains of this type carry at least three R plasmids. Gentamicin resistance appeared in DT204c in 1983 and plasmids conferring resistance to gentamicin also code for resistance to apramycin. Three types of apramycin-gentamicin resistance plasmid have been identified.