Abstract

Discrimination of Strains of Salmonella enteritidis with Differing Levels of Virulence by an In Vitro Glass Adherence Test C. Solano 1 , B. Sesma 2 , M. Alvarez 2 , T. J. Humphrey 3 , C. J. Thorns 4 , and C. Gamazo 1 , * Departamento de Microbiologı́a, Universidad de Navarra, 1 and Instituto de Salud Pública de Navarra, 2 Pamplona 31080, Spain, and PHLS Food Microbiology Research Unit, Heavitree, Exeter EX25 AD, 3 and Bacteriology Department, Central Veterinary Laboratory, New Haw, Addlestone, Surrey KT15 3NB, 4 United Kingdom ABSTRACT The objective of this study was the in vitro differentiation of isolates of Salmonella enteritidis whose virulences differed in a chick model. A total of 14 strains of S. enteritidis were isolated from either the environment, dairy products, or infected patients. The isolates could be divided into two groups on the basis of their virulence (50% lethal dose) in chickens infected intraperitoneally. When the strains were incubated in adherence test medium (Spanish patent 9700408), only the virulent strains produced aggregates and formed visible filaments attached to the glass tube. These results suggest, although for a limited number of strains, that aggregation in such a medium could be used as a diagnostic tool to discriminate virulent strains of S. enteritidis.