Genomic Comparison of Salmonella Enteritidis Strains Isolated from Laying Hens and Humans in the Abruzzi Region during 2018.

Lisa Di Marcantonio,Romina Romantini,Elisabetta Di Giannatale,Anna Janowicz,Tiziana Persiani,Guido Di Donato,Katiuscia Zilli,Daniela Paganico,Stefano Bilei

doi:10.3390/pathogens9050349

Abstract

Salmonellosis is a major cause of bacterial foodborne infection. Since 2016, an increased number of cases of gastroenteritis caused by Salmonella enterica serovar Enteritidis linked to eggs produced in Poland has been reported in Europe. In Italy, S. Enteritidis is one of the three most commonly reported serotypes, associated mainly with the consumption of contaminated eggs and derived products. In our work, we analysed 61 strains of S. Enteritidis obtained from humans and farms in the Abruzzi region, Italy, in 2018. We used Multiple-Loci Variable-Number Tandem Repeat (VNTR) analysis (MLVA)-based typing and Whole-Genome Sequencing (WGS) tools to identify closely related strains and perform cluster analysis. We found two clusters of genetically similar strains. The first one was present in the local farms and isolated from human cases and had single-linkage distance of no more than two core genes and less than five Single-Nucleotide Polymorphisms (SNPs). The second cluster contained strains isolated from humans and from a dessert (tiramisù) sample that shared identical core genome and were assigned the same SNP address. Cluster 2 isolates were found to be genetically similar to an S. Enteritidis strain from a multi-country outbreak linked to Polish eggs.

Highlights

Salmonellosis is the second most common gastrointestinal disease in Europe
The second cluster contained strains isolated from humans and from a dessert sample that shared identical core genome and were assigned the same Single-Nucleotide Polymorphisms (SNPs) address
90,000 confirmed salmonellosis cases were reported in the European Union, half of which were caused by Salmonella enterica serotype Enteritidis

Summary

Introduction

Salmonellosis is the second most common gastrointestinal disease in Europe. 90,000 confirmed salmonellosis cases were reported in the European Union, half of which were caused by Salmonella enterica serotype Enteritidis. The majority of these cases were linked to the consumption of eggs and egg-containing products, followed by that of bakery and mixed foods [1]. In Italy, 3635 cases of Salmonella infection were officially reported in 2018. More than 150 local human outbreaks were related to food consumption, and 34 were water-borne. In contrast to what observed in the EU, in Italy, Enteritidis was the third most common serovar isolated from patients after Typhimurium and a monophasic variant of Salmonella Typhimurium. Enteritidis in the same year [1]

Objectives

Methods

Conclusion