A molecular study of Salmonella strains identified from two food-poisoning outbreaks.

A molecular epidemiology study was carried out on Salmonella mbandaka and Salmonella corvallis strains identified from two food-poisoning outbreaks which occurred in August 1985 in Pistoia and in October 1985 in Sant'Ilario d'Enza (RE). All the Salmonella mbandaka strains were plasmid-free; all the epidemic Salmonella corvallis strains, in contrast to the non epidemic isolates, carried a small plasmid of approximately 2 MDa molecular weight. Restriction enzyme cleavage pattern analysis revealed that the plasmids of the epidemic strains were closely related.