Differentiation of strains from a food-borne outbreak of Salmonella enterica by phenotypic and genetic typing methods.

A combination of typing methods was used to identify the strains and the infection source in a food-borne outbreak of Salmonella enterica occurring in a summer camp and affecting 25 children. All isolates tested were found to be serovar Enteritidis, with an identical biotype API 20E and ribotype. However, they differed in their plasmid profiles and/or antibiograms, and were grouped into three strains. One strain was found in human stools, another in a hen's egg, and the third in both stools and another egg pointing to large Spanish omelettes to be the contaminated food source.