Core Genome Multilocus Sequence Typing for Food Animal Source Attribution of Human Campylobacter jejuni Infections

Area of Science:

• Microbiology
• Food Safety
• Genomics

Background:

• Campylobacter jejuni is a leading cause of bacterial enteritis globally.
• Understanding the sources of C. jejuni infections is crucial for public health interventions.

Purpose of the Study:

• To evaluate the utility of core genome multilocus sequence typing (cgMLST) for subtyping C. jejuni isolates.
• To determine the genetic relatedness between C. jejuni from food animals, retail meats, and human infections.
• To investigate the association between antimicrobial resistance genes and specific C. jejuni subtypes.

Main Methods:

• Whole genome sequencing (WGS) of 622 C. jejuni isolates from food animals and retail meats (2013-2017).
• Integration of WGS data from 222 human isolates from NCBI.
• Analysis using core genome multilocus sequence typing (cgMLST) with varying allelic difference (AD) thresholds and traditional MLST.
• PorA sequencing for virulence clone identification.
• Detection and analysis of antimicrobial resistance genes and mutations.

Main Results:

• The cgMLST scheme with an AD of 200 (cgMLST200) demonstrated strong correlation with traditional MLST.
• Significant proportions of food animal and retail meat isolates shared cgMLST sequence types with human isolates (e.g., 78.9% of beef cattle isolates).
• Specific cgMLST types were strongly linked with particular antimicrobial resistance genotypes, such as macrolide and quinolone resistance.

Conclusions:

• The cgMLST200 threshold provides a robust subtyping scheme for C. jejuni.
• This approach facilitates the source attribution of human C. jejuni infections by linking them to food sources.
• Combining cgMLST with antimicrobial resistance profiling enhances its value for epidemiological investigations.