Contamination Pathways can Be Traced along the Poultry Processing Chain by Whole Genome Sequencing of Listeria innocua

Abstract

Foodborne infection with Listeria causes potentially life-threatening disease listeriosis. Listeria monocytogenes is widely recognized as the only species of public health concern, and the closely related species Listeria innocua is commonly used by the food industry as an indicator to identify environmental conditions that allow for presence, growth, and persistence of Listeria spp. in general. In our study, we analyze the occurrence of Listeria spp. in a farm-to-fork approach in a poultry production chain in Egypt and identify bacterial entry gates and transmission systems. Prevalence of Listeria innocua at the three production stages (farm, slaughterhouse, food products) ranged from 11% to 28%. The pathogenic species Listeria monocytogenes was not detected, and Listeria innocua strains under study did not show genetic virulence determinants. However, the close genetic relatedness of Listeria innocua isolates (maximum 63 SNP differences) indicated cross-contamination between all stages from farm to final food product. Based on these results, chicken can be seen as a natural source of Listeria. Last but not least, sanitary measures during production should be reassessed to prevent bacterial contamination from entering the food chain and to consequently prevent human listeriosis infections. For this purpose, surveillance must not be restricted to pathogenic species.

Backtracking and forward checking of human listeriosis clusters identified a multiclonal outbreak linked to Listeria monocytogenes in meat products of a single producer

“…Molecular surveillance of L. monocytogenes using whole genome sequencing (WGS), combined with epidemiological evidence, has greatly facilitated listeriosis outbreak clarification [9][10][11][12][13]. In addition, WGS analysis enables detailed insights into industrial hygiene and forms the basis for in-depth root cause analysis [14].…”

Listeria Occurrence in Conventional and Alternative Egg Production Systems

“…As such, the infection is generally subclinical and can pass on through the environment and onto the eggs without persistent symptoms throughout the flock [ 61 , 64 ]. Gastrointestinal infection results in contaminated fecal material, which can contaminate the feed, water, and pen environment [ 65 ].…”