A Salmonella enterica subsp. enterica serovar Enteritidis foodborne outbreak after consumption of homemade lasagne

In the latest year, and also in 2013, Salmonella was the most frequently detected causative agent in foodborne outbreaks (FBOs) reported in Europe. As indicated in EFSA report (2015) the serotypes mostly associated to FBOs are S. Typhimurium and Enteritidis; while Salmonella Typhimurium is generally associated with the consumption of contaminated pork and beef, FBOs due to Salmonella Enteritidis are linked to eggs and poultry meat. In this study it is described the investigation of a domestic FBO involving four adults and linked to homemade lasagne. Investigations were performed to determine the relatedness of Salmonella strains, identify the sources of infection, and trace the routes of Salmonella contamination in this FBO. Salmonella strains were isolated in 3 out of 4 patient stool samples and from lasagne and all of them were serotyped as S. Enteritidis. Pulsed-field gel electrophoresis (PFGE) analysis revealed the genotypical similarity of the all the strains. Although serotyping and PFGE analysis identified the common food source of infection in this FBO, it was not possible to determine how or at what point during food preparation the lasagne became contaminated with Salmonella.