Investigating the dynamics of Salmonella contamination in integrated poultry companies using a whole genome sequencing approach

Abstract

The study of non-typhoid Salmonella in broiler integrations has been limited by the resolution of typing techniques. Although serotyping of Salmonella isolates is used as a traditional approach, it is not of enough resolution to clearly understand the dynamics of this pathogen within poultry companies. The aim of this research was to investigate the epidemiology and population dynamics of Salmonella serotypes in 2 poultry integrations using a whole genome sequencing approach. Two hundred and forty-three Salmonella isolates recovered from the broiler production chain of 2 integrated poultry companies were whole genome sequenced and analyzed with dedicated databases and bioinformatic software. The analyses of sequences revealed that S. Infantis was the most frequent serotype (82.3%). Most isolates showed a potential for resistance against medically important antibiotics and disinfectants. Furthermore, 97.5% of isolates harbored the pESI-like mega plasmid, that plays an important role in the global dissemination of AMR. SNP tree analysis showed that there were clones that are niche-specific while other ones were distributed throughout the broiler production chains. In this study, we demonstrated the potential of whole genome sequencing analysis for a comprehensive understanding of Salmonella distribution in integrated poultry companies. Data obtained with these techniques allow determination of the presence of genetic factors that play an important role in the environmental fitness and pathogenicity of Salmonella.

Keywords: Salmonella Infantis; WGS; antimicrobial resistance; pESI-like; poultry production chain.

Figure 1

SNP tree analysis of S. Infantis isolates of integration A.

Figure 2

SNP tree analysis of S. Infantis isolates of integration B.

Figure 3

General plasmid alignment of pESI-like plasmid PSI-like plasmids showed high similarity with the Peruvian reference. However, entire blocks are reorganized or absent in some strains. A dynamic view of the alignment can be seen in Supplementary File 3.