Epidemiological and molecular investigations of sequential outbreaks of Campylobacter jejuni infecting adults and schoolchildren in southeastern China, 2021-2022

Abstract

To investigate cases of five Campylobacter jejuni outbreaks and describe laboratory characteristics of these infections. Whole genome sequencing and conventional methods were combined to thoroughly investigate the outbreaks, and data of contemporaneous sporadic cases was included for comparison. Seven sequence types (ST) of C. jejuni caused 83 cases, including ST9079 which recurred across two years. Trace-back investigation could not identify any food items of infection, but detected identical campylobacters from food contacts. Phylogenetic analysis unveiled genetic closeness between outbreak strains and some concurrent sporadic strains, indicating local campylobacteriosis may not be wholly sporadic but rather a series of linked cases. Virulence genes disclosed species/case-specific signatures to differentiate outbreak from truly non-outbreak strains. Resistance to fluoroquinolones and/or macrolides was prevalent (90.8%, 108/119), with a noteworthy portion exhibiting multidrug resistance (31.1%, 37/119). Five types of plasmids were harbored among outbreak isolates, which one plasmid harboring anti-stress and resistant genes was rarely found in C. jejuni. This is the first reported sequential outbreaks of C. jejuni in China. Our observations help to define the genomic landscape and antimicrobial resistance patterns of Campylobacter, emphasizing the need for a broader 'One Health' perspective to combat the threats posed by campylobacteriosis.