Diagnosis by a Combination of Typing Methods of a Salmonella typhimurium Outbreak Associated with Cured Ham

Abstract

This paper describes the usefulness of combining typing methods (antibiotyping, phage typing, plasmid profile, and ribotyping) in the characterization of a Salmonella enterica serotype Typhimurium (S. typhimurium) strain as the causal agent of an outbreak associated with cured ham, Serrano variety, which is an unusual infection source of Salmonella. Human isolates and the majority of ham isolates showed identical biochemical profiles, antibiotypes, plasmid profiles, and ribotypes. However, some ham isolates showed a different plasmid profile. Phage typing was inconclusive where no isolate corresponded to recognized phage types. Ribotyping was also used to confirm the epidemiological relationship of the outbreak strain with an endemic clonal line of S. typhimurium in Asturias. This was defined in terms of combined ribotype with four restriction endonucleases (EcoRI, SalI, PvuII and PstI).