Antimicrobial resistance and genomic characteristics of Campylobacter jejuni isolates from clinical and food sources in Nan'an District,Chongqing
Objective To analyze the antimicrobial resistance and genomic characteristics of Campylobacter jejuni strains isolated from human and food sources in Nan'an District of Chongqing,and conduct the traceability analysis to provide scientific basis for precise prevention and control of Campylobacter jejuni infection in the region.Methods The strain of Campylobacter jejuni was isolated and identified from fecal samples of 336 diarrhea patients treated at 6 sentinel hospitals in Nan'an District of Chongqing,and 60 raw poultry meat samples collected by the National Food Safety Risk Monitoring Project from 2021 to 2022.20 isolated strains of Campylobacter jejuni(15 clinical strains and 5 food strains)were subjected to drug sensitivity testing,pulsed-field gel electrophoresis(PFGE)typing,whole genome sequencing and comparison with the public database genomes.The sequencing data was then used to perform core genome multilocus sequence typing(cgMLST)of the strains,drug-resistant genes analysis.A phylogenetic tree of 20 strains from Nan'an District and 29 strains from the public database was constructed.Results The multiresistance rate of clinical and food strains of Campylobacter jejuni in Nan'an District was 70.00％.The 20 strains of Campylobacter jejuni were categorized into 19 MLST types,19 cgMLST types and 18 PFGE bands.The phylogenetic analysis showed that the evolutionary distance between the 4 food strains(2022NAF01,2022NAF02,2022NAF03,2022NAF04)isolated from poultry in Nan'an District and the 4 clinical strains(2021NAP02,2021NAP01,2021NAP03,2022NAP04)was closer,the evolutionary distance between the 6 strains in Nan'an District and 4 strains of Beijing was closer.Conclusion The prevalent strains of Campylobacter jejuni in Nanan District of Chongqing were polymorphic,with diversity in genetic characteristics and high multidrug resistance.
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