Virulence and Antimicrobial Resistance in Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and Campylobacter coli account for most recognized cases of human campylobacteriosis. For C. coli, gene-carriage surveys often stand in for direct tests of function; this distinction is maintained throughout the review. Virulence is discussed as a sequence of events rather than as a catalogue of factors. Motility and adhesion have the most reproducible support during colonization and epithelial contact, whereas biofilm formation, quorum sensing, and T6SS-associated phenotypes vary substantially across strains and models. We then consider host–cell injury, persistence, transmission, and the uncommon post-infectious outcomes linked to sialylated LOS. Antimicrobial resistance is treated in parallel, with emphasis on target-site change, ribosomal protection or methylation, enzymatic inactivation, and CmeABC-mediated efflux. The One Health model places both species within overlapping animal, food, and environmental reservoirs rather than assigning C. jejuni exclusively to poultry or C. coli to swine. A narrower conclusion emerges from the resistance-fitness literature: gyrA Thr-86-Ile and CmeABC can alter colonization or competitive fitness, but the available data do not show that resistance generally predicts more severe human disease. This distinction frames the proposed priorities for surveillance and intervention.