Drug resistance and molecular epidemiology of Salmonella Kentucky in Luoyang,Henan,2020-2021
Objective To investigate the drug resistance profile and molecular epidemiological characteristics of Salmonella Kentucky strains isolated from the feces of broiler supply chain and diarrhea patients in Luoyang City,Henan Province,so as to provide a scientific basis for the development of prevention and control strategies.Methods Drug susceptibility testing of 14 antibiotics was conducted on 19 strains of Salmonella Kentucky from Luoyang City between 2020 and 2021.Whole genome sequencing was used for multi-locus sequence typing and identification of resistance genes.PFGE and whole genome were used for the molecular epidemiological analysis.Results Out of the 19 strains sixteen were from the broiler breeding and slaughtering process,and there were from the feces of diarrhea patients.All strains were 100.00％resistant to ciprofloxacin and gentamicin,with high resistant rate of 94.74％to ampicillin,tetracycline and chloramphenicol.Resistance rate to cefotaxime and azithromycin were 84.21％and 68.42％,respectively.All strains belonged to ST198,with double mutations of gyrA and parC in the quinolone resistance determining region(QRDR)on the chromosome.The types of mutations were gyrA(ASP87Asn,Ser83Phe),parC(Thr57Ser,Ser80Ile,Ser395Asn,Ala469Ser and Thr620Ala).Plasmid-mediated resistance gene(PMQR)QnrS1 was detected in 52.63％of the strains.β-lactam resistance genes were dominated by blacrx-M-55(68.42％)and blaTEM-1(26.32％).The detection rates of macrolide resistance genes mphA and Mrx were in 78.95％and 89.47％of the strains,respectively.The high detection of resistance genes was consistent with their high resistance phenotypes.PFGE clustering analysis and genome-wide phylogenetic tree showed high homology between some chicken and human origin strains Conclusions The Salmonella Kentucky strains isolated are all ST198 type,exhibit high drug resistance,and carry relevant resistance genes.There is significant homology between some chicken and human strains,suggesting potential disseminated of infections.Enhanced monitoring of multi-drug-resistant Salmonella Kentucky in poultry farming is recommended.
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