Comparative genomic analysis of food-originated plasmids identified in Campylobacter jejuni and C. coli

Authors: He, Yiping; Dykes, Gretchen; Kanrar, Siddhartha; Liu, Yanhong; Gunther, Nereus; Counihan, Katrina; Lee, Joseph; Capobianco Jr, Joseph

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2025
Publication Date: 1/18/2025
Citation: He, Y., Dykes, G.E., Kanrar, S., Liu, Y., Gunther, N.W., Counihan, K.L., Lee, J., Capobianco Jr, J.A. 2025. Comparative genomic analysis of food-originated plasmids identified in Campylobacter jejuni and C. coli. Microorganisms. 13,206. https://doi.org/10.3390/microorganisms13010206.
DOI: https://doi.org/10.3390/microorganisms13010206

Interpretive Summary: Campylobacter is a leading bacterial cause of foodborne illness worldwide, responsible for an estimated 400 million cases of infection annually. Most cases are acquired through the consumption of undercooked poultry or other meat. In this study, the authors used whole genome sequencing technologies to identify 34 plasmids (mobile genetic elements) in Campylobacter strains isolated from retail meat. Comprehensive genetic analysis revealed that the plasmids contain virulence, antibiotic resistance, and self-mobilization genes. High degree of genetic similarity was found within the groups of plasmids, indicating the potential for spread of virulence and antibiotic resistance between bacterial strains. This study provides valuable information that can be used to develop targeted interventions to more effectively detect and control the spread of this important pathogen.

Technical Abstract: Campylobacter is one of the leading bacterial causes of gastroenteritis worldwide. It frequently contaminates poultry and other raw meat products, which are the primary sources of Campylobacter infections in human. Plasmids, known as important mobile genetic elements, often carry genes for antibiotic resistance, virulence, and self-mobilization genes. They serve as the main vectors for transferring genetic material and spreading resistance and virulence between bacteria. In this study, we identified 34 new plasmids from 43 C. jeuni and C. coli strains isolated from retail meat using long-read and short-read genome sequencing. Phylogenetic analysis of the relatedness and diversity among the plasmid assemblies and reference plasmids from GenBank revealed five distinct groups, namely, pTet, pVir, mega plasmids (>80 kb), mid plasmid (~30 kb), and small plasmids (<6 kb). Pangenomic analysis identified the core and accessory genes in each group, indicating a high degree of genetic similarity within groups and substantial diversity between the groups. Gene annotation showed all the pTet plasmids contain the tetO gene, which was determined to be the genetic cause of tetracycline resistance in host strains. The large plasmids, particularly the mega plasmids carry multiple genes (e.g., aph(3’)-III, type IV and VI secretion systems, and type II toxin-antitoxin systems) important for plasmid mobilization, virulence, antibiotic resistance, and the persistence of Campylobacter. Together, the identification and comprehensive genetic characterization of new plasmids from Campylobacter food isolates contributes to understanding the mechanisms of gene transfer, particularly the spread of genetic determinants of virulence and antibiotic resistance in this important pathogen.