Campylobacter spp. is the leading cause of foodborne gastrointestinal infections in humans worldwide. This study reports the first case of four family members who had contact with the same source of Campylobacter jejuni contamination with different results. Only the little siblings were infected by the same C. jejuni strain, but with different symptoms. Whereas the daughter was slightly affected with mild enteritis, the son suffered a longer campylobacteriosis followed with a perimyocarditis. This is the first case of the youngest patient affected by C. jejuni-related perimyocarditis published to date. The genomes of both strains were characterized by whole-genome sequencing and compared with the C. jejuni NCTC 11168 genome to gain insights into the molecular features that may be associated with perimyocarditis. Various comparison tools were used for the comparative genomics analysis, including the identification of virulence and antimicrobial resistance genes, phase variable (PV) genes, and single nucleotide polymorphisms (SNPs) identification. Comparisons of the strains identified 16 SNPs between them, which constituted small but significant changes mainly affecting the ON/OFF state of PV genes after passing through both hosts. These results suggest that PV occurs during human colonization, which modulates bacteria virulence through human host adaptation, which ultimately is related to complications after a campylobacteriosis episode depending on the host status. The findings highlight the importance of the relation between host and pathogen in severe complications of Campylobacter infections.
Keywords: antimicrobial resistance genes; campylobacteriosis; clinical case; perimyocarditis; phase variation; virulence genes.