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Updated: Apr 22, 2026

Heuristic Mining of Hierarchical Genotypes and Accessory Genome Loci in Bacterial Populations
Published on: December 7, 2021
Genome-based source attribution using a One Health Escherichia coli isolate collection from 2013 to 2023 in Scotland.
Antonia Chalka1,2, Louise Crozier2, Adriana Vallejo-Trujillo1,2
1The Roslin Institute and Royal (Dick) School of Veterinary Medicine, University of Edinburgh, Easter Bush Estate, Edinburgh, Scotland, EH25 9RG, UK.
This study used random forest models to trace Escherichia coli (E. coli) contamination sources. A significant livestock E. coli signal was found in 15% of human clinical isolates, highlighting agri-food chain transmission risks.
Area of Science:
- Microbiology
- Genomics
- Epidemiology
Background:
- Escherichia coli (E. coli) is a significant cause of human infections.
- Understanding E. coli transmission routes is crucial for public health.
- Whole-genome sequencing provides high-resolution data for microbial source tracking.
Purpose of the Study:
- To develop and apply random forest-based source attribution models for E. coli.
- To investigate the potential sources of E. coli contamination in food, shellfish, and water samples.
- To assess the contribution of livestock and human sources to E. coli infections.
Main Methods:
- Development of random forest models using 4,230 E. coli whole-genome assemblies.
- Analysis of E. coli isolates from diverse sources including wastewater, livestock, food, and clinical infections.
- Probabilistic assignment of E. coli isolates to potential livestock and human sources.
Main Results:
- A livestock E. coli signal was identified in 15% of human clinical isolates.
- E. coli isolates from food and water frequently showed co-attribution to both livestock and human sources.
- Only 2.3% of food E. coli isolates were linked to human bacteraemia/UTI sequence types.
Conclusions:
- Source attribution models are valuable tools for national E. coli surveillance.
- Findings suggest routine human exposure to specific livestock E. coli strains via the agri-food chain.
- This research supports risk management strategies to protect public health from E. coli transmission.
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