Abstract:

Objective To investigate drug resistance of Salmonella enteritidis isolated from diarrhea cases in Chengde City，and analyze the association between drug resistance phenotype and drug resistance genotype. Methods Thirty strains of Salmonella enteritidis isolated from feces of diarrhea patients in sentinel hospital of Chengde City from 2022 to 2023 were collected，and serological identification，drug susceptibility test and whole genome sequencing were carried out. According to the sequencing results，the serotypes and drug resistance genotypes of the tested strains were obtained from the SeqSero2 serotyping database and ResFinder resistance gene database on the website of the center for genomic epidemiology（CGE），and the drug resistance phenotypes and drug resistance genes were analyzed. Results Totally 30 strains were identified as Salmonella enteritidis by routine serotyping method，which was consistent with the serotype predicted by SeqSero2 database. All strains were resistant to nalidixic acid，followed by ampicillin，streptomycin，ampicillin/sulbactam and tetracycline，with drug resistance rates of 73.33%，46.67%，36.67% and 30.00%，respectively，and multi-drug resistance rate of 53.33%. A total of 23 drug resistance genes in 7 classes were detected by whole genome sequencing，and aminoglycoside drug resistance genes carried the highest rate. The overall coincidence rate of drug resistance phenotype and drug resistance genotype was 92.94%，and the results of drug resistance of tetracycline，ciprofloxacin， azithromycin and chloramphenicol were completely consistent with the sequencing results. Conclusion Salmonella enteritidis in Chengde area has serious drug resistance and multiple drug resistance，and whole genome sequencing can accurately predict its serotype and drug resistance genotype.

Key words: Salmonella enteritidis, Serotype, Drug resistance, Whole genome sequencing, Drug resistance genotype