Genomic perspectives on foodborne illness

Area of Science:

• Microbiology and Public Health
• Genomics and Infectious Disease Epidemiology

Background:

• Whole-genome sequencing (WGS) is crucial for public health to trace foodborne illness outbreaks to their source.
• Sporadic food poisoning cases are common but often too small to warrant detailed investigation.
• Understanding the dynamics of pathogen evolution and transmission is key to preventing foodborne diseases.

Purpose of the Study:

• To analyze clusters of bacterial pathogen genomes (Salmonella, E. coli, Campylobacter, Listeria) with minimal mutations.
• To gain new insights into the nature and duration of food contamination episodes.
• To investigate age-related susceptibility and geographic variations in pathogen prevalence.

Main Methods:

• Analysis of whole-genome sequences from clinical isolates of four key bacterial pathogens.
• Clustering analysis of isolates differing by a small number of mutations to identify transmission chains.
• Examination of age distribution, geographic spread, and temporal persistence of identified clusters.

Main Results:

• Younger age groups exhibit increased susceptibility to Salmonella, E. coli, and Campylobacter infections.
• Significant regional variations in Salmonella serovar frequencies were observed across the United States.
• A substantial proportion of contamination episodes, particularly for Salmonella, are long-lasting (up to three years).

Conclusions:

• WGS-based cluster analysis provides a deeper understanding of foodborne contamination events.
• Foodborne pathogens frequently cause multi-state outbreaks linked to commercially distributed foods.
• Salmonella infections in infants under six months are often due to cross-contamination rather than primary formula contamination.