Abstract:

Objective To analyze the distribution of drug resistance genes and virulence genes in Campylobacter，as well as the molecular prevalence and homology characteristics of Campylobacter from different sources，and to provide a reference for infection prevention and control. Methods For 913 anal swab samples of patients with diarrhea，701 samples of poultry meat and 1 sample of chicken manure in Songjiang Shanghai from 2017 to 2021，Campylobacter jejuni and Campylobacter coli were identified，and the genomes of the determined Campylobacter were determined by whole genome sequencing（WGS）. The carriage of related drug resistance genes and virulence genes，as well as the multilocus sequence typing（MLST）characteristics，were analyzed. Results Among the 913 anal swab samples，115 isolates（12.60%） of Campylobacter were determined（96 isolates of Campylobacter jejuni and 19 isolates of Campylobacter coli）. Totally，78 isolates（11.13%） of Campylobacter were found in 701 poultry meat food samples（31 isolates of Campylobacter jejuni and 47 isolates of Campylobacter coli）. There was no statistical significance in the determination rate of Campylobacter between the 2 types of samples（χ² =0.813，P=0.367）. In the 193 Campylobacter isolates，101 isolates met the sequencing requirements，and the sequencing data were available（56 isolates were isolated from anal swab samples of diarrhea patients and 45 isolates were isolated from poultry meat food samples）. The mutation rate of gyrA gene was the highest among 9 drug resistance genes，and that of tet（M）gene was the lowest. Isolates carrying more than 3 types of drug resistance genes accounted for 90.10%. Among the 6 drug resistance genes [gyrA mutation，erm（B），tet（O），tet（M），blaOXA，cat]，the carrying rates in anal swab and food samples were not statistically significant（P>0.05）. The carrying rates of 9 virulence genes were 100% for iamA，ciaB and cheY. The carrying rates of cadF，cdtB and cdtA were all >95%. The carrying rates of flaA and virB11 were <6%. All isolates carried 3 or more virulence genes，and the carrying rates of 7 virulence genes [cadF，flaA，virB11，cdtB，iamA，ciaB，cheY] in anal swab and food samples were not statistically significant（P>0.05）. MLST classified 102 isolates of Campylobacter（including 1 isolate from chicken manure sample）into 68 different ST types（10 new ST types）and 16 clonal groups [C828 was the most important clonal group（56 isolates，54.9%）]. Among the 3 main clonal groups，CC828 and CC21 isolates were mainly isolated from anal swab samples of diarrhea patients and poultry meat food samples，while CC354 isolates were mainly isolated from anal swab samples of diarrhea patients. Conclusions There is no significant difference in the determination rate of Campylobacter in anal swab samples of patients with diarrhea and poultry meat food samples. The types of drug resistance genes and virulence genes are numerous，and the carrying rates are high. There are 3 main clonal groups and 68 ST types（including 10 new ST types）in MLST. The Campylobacter has high drug resistance and pathogenicity，and the MLST types are diverse. Relevant departments can formulate measures for preventing and controlling the spread of Campylobacter infection based on this.

Key words: Campylobacter, Whole genome sequencing, Drug resistance gene, Virulence gene, Multilocus sequence typing