The Value of Plasmid Studies in the Epidemiology of Infections Due to Drug-Resistant Salmonella wien

Abstract

Since 1969 strains of Salmonella wien that are resistant to multiple antibacterial drugs have caused widespread epidemics of enteritis in Europe and North Africa. Of 113 British strains examined between January 1970 and January 1977, 67 were multiresistant. These strains and 22 strains from six other countries were examined to determine their plasmid content. Two plasmids were found in the vast majority of strains: an F_Ime factor, conferring resistance to ampicillin, chloramphenicol, kanamycin, streptomycin, spectinomycin, sulfonamides, and tetracyclines (ACKSSpSuT), and a nonautotransferring plasmid of resistance type ASSu. The F_Ime plasmids have dual incompatibility: they are incompatible with group F_I factors and with the MPIO plasmid of Salmonella typhimurium, which belongs to a separate group. Other plasmids found in S. wien included principally a Colla factor and an autotransferring plasmid that codes for ampicillin resistance and belongs to compatibility group I₂, The similarity in plasmid content of strains isolated in widely separated areas suggests that they have a clonal origin.