USE OF PLASMID PROFILE TYPING FOR SURVEILLANCE OF SALMONELLA-ENTERITIDIS PHAGE TYPE-4 FROM HUMANS, POULTRY AND EGGS

Plasmids were found in 1022 of 1089 (94%) of drug-sensitive strains of Salmonella enteritidis phage type 4 from humans (sporadic and outbrea k cases), poultry (chickens) and eggs in England and Wales in the Ei-y ear period 1988-92 and 25 plasmid profile patterns were identified. St rains characterized by a single plasmid of 38 MDa predominated (= plas mid profile type SE 38), comprising over 90% of isolates from humans, 70% from poultry and 92% from eggs. Eleven profile types were identifi ed in strains from humans, 21 in strains from poultry and 3 in strains from eggs. Eight of the 11 patterns identified in human isolates were found in strains from poultry and 2 in strains from eggs. In contrast 15 patterns seen in poultry were not found in strains from humans. Po ur percent of strains from humans and 13% from poultry did not carry t he 38 MDa plasmid but all strains from eggs were found to carry this p lasmid. The second most common profile type in strains isolated betwee n 1981 and 1988 was not identified in strains isolated from 1988-92. I t is concluded that plasmid profile typing is a useful method for rapi d differentiation within phage type 4 of S. enteritidis but that metho ds which can discriminate within the predominant profile type, SE 38, are now required.