Food contamination incident linked to Salmonella Enteritidis ST11 in egg-based products

Salmonella enterica remains one of the leading causes of foodborne outbreaks in the European Union. Salmonella Enteritidis is the serovar most frequently reported in outbreak settings, with eggs and egg products representing major vehicles of infection. The predominant sequence type, ST11, is globally distributed and comprises several phylogenetic lineages characterised by limited genomic diversity within lineages, that can complicate outbreak investigations by resulting in highly similar whole genome sequencing (WGS) profiles among epidemiologically unrelated isolates. This report describes a food contamination incident identified in France between May and July 2026 involving four distinct outbreaks of S. Enteritidis ST11 infections geographically dispersed. Epidemiological and microbiological investigations confirmed homemade egg-based products as the vehicle of infections. This was further supported by the identification of five food isolates, collected from eggs and egg-based products sampled at the patients' places, that belong to two distinct strains. These isolates matched the two human representative strains of the four French outbreaks. Food traceability investigations linked all outbreaks to a common egg distribution network involving two packing centres and three laying-hen farms belonging to the same food group in Poland. These farms had previously been associated with the multinational polyclonal salmonellosis outbreak linked to eggs that affected 18 European countries between 2016 and 2020. Similar to that earlier event, multiple S. Enteritidis ST11 strains were identified in this incident in 2026. The repeated detection of Salmonella in eggs originating from the same production group suggests persistent Salmonella contamination or possible reintroduction upstream in the egg production chain. These findings highlight the need for further investigations to identify the possible root causes of vertical and/or horizontal contamination. Moreover, the detection of a human and non-human cluster spanning France and other countries in 2026 suggests the possible cross-border dimension of the incident and warrants further investigation.