Identification of genetic determinants that drive population differentiation and host adaptation in Campylobacter jejuni in California

Evangelos A. Dimopoulos, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
Caitlin E. Collins, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
Maliha Aziz, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Daniel E. Park, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Vanessa H. Quinlivan, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Julio Diaz Caballero, Centre for Genomic Pathogen Surveillance, Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.
Sara Y. Tartof, Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA.
Remy Hilsabeck, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Harpreet S. Takhar, Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA.
Keeve Nachman, Johns Hopkins Risk Sciences and Public Policy Institute, Baltimore, MD, USA.
David M. Aanensen, Centre for Genomic Pathogen Surveillance, Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.
Cindy M. Liu, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Lance B. Price, Antibiotic Resistance Action Center, Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC, USA.
Julian Parkhill, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.

Document Type

Journal Article

Publication Date

12-1-2025

Journal

Microbial genomics

Volume

11

Issue

12

DOI

10.1099/mgen.0.001589

Keywords

Campylobacter jejuni; antimicrobial resistance; genomics; host adaptation; pathogen evolution; population structure

Abstract

Campylobacter jejuni is a commensal bacterium that colonizes livestock and wild animals and is responsible for more than 80% of campylobacteriosis cases in humans, which all ultimately have an animal source. Its high genome plasticity and recombination rate allow it to adapt to multiple hosts and lead to the rapid emergence of lineages, some of which can be antibiotic resistant. Our aim in this study was to examine the population structure of Campylobacter in California and assess its differentiation between animal hosts and humans. We sequenced 69 human clinical isolates of C. jejuni from California and collected a dataset of human and animal Californian genomes to contextualize them. By comparing groups of isolates, we detected significant levels of differentiation between the human and animal Californian isolates. Through phylogenetic reconstruction, we demonstrated that, as expected, the human C. jejuni clinical isolates were derived from both avian and ruminant sources but represented a distinct subset of those populations. By identifying the genomic regions that were contributing to population differentiation amongst the host groups, we were able to identify protein variants potentially responsible for host adaptation and propensity to cause infection in humans.

Department

Environmental and Occupational Health

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