绍兴市市售生畜肉沙门菌分子分型与耐药分析

Molecular typing and drug resistance of Salmonella in market-sold raw livestock meats in Shaoxing City

目的了解浙江省绍兴市市售生畜肉中沙门菌的分子分型与耐药特征,为耐药沙门菌防控提供依据。方法于2023年3—11月采集绍兴市超市、农贸市场和餐饮店生畜肉样品检测沙门菌,进行血清分型;采用脉冲场凝胶电泳(PFGE)和多位点序列分型(MLST)进行分子分型;采用微量肉汤稀释法和全基因组测序(WGS)进行耐药表型和耐药基因分析。结果329份生畜肉中检出沙门菌34株,检出率为10.33%;检出14种血清型,优势血清型为里森沙门菌和伦敦沙门菌,分别为9和8株,占26.47%和23.53%。PFGE分型获得31种带型图谱和23个带型簇,相似度为30.80%~100.00%,无明显优势带型。MLST共检出15种序列型别(ST),其中里森沙门菌均为ST469型,伦敦沙门菌均为ST155型。对四环素和氨苄西林的耐药率较高,分别为44.12%和35.29%。共产生13种耐药谱,其中8种为多重耐药谱,多重耐药率为29.41%。检测到8类14种耐药基因,其中氨基糖苷类耐药基因aac(6')-Iaa携带率为100.00%;苯丙醇类抗生素耐药表型与耐药基因一致率最高,为97.06%;喹诺酮类抗生素耐药表型与耐药基因无一致性。结论绍兴市市售生畜肉样品检出的沙门菌血清型以里森沙门菌和伦敦沙门菌为主;PFGE带型呈现多态性,MLST主要为ST469型和ST155型;对四环素和氨苄西林耐药率较高,存在多重耐药现象。

Objective To investigate the molecular typing and drug resistance of Salmonella in market-sold raw live⁃stock meats in Shaoxing City,Zhejiang Province,so as to provide the basis for the prevention and control of drug-resis⁃tant Salmonella.Methods Salmonella isolates were detected and serotyped from raw livestock meat samples collected from supermarkets,agricultural markets and restaurants in Shaoxing City between March and November 2023.Molecular typing was performed using pulsed-field gel electrophoresis(PFGE)and multilocus sequence typing(MLST).Antibiotic resistance phenotypes and resistance gene analyses were conducted using broth microdilution method and whole genome sequencing.Results A total of 34 Salmonella isolates were detected from 329 samples and the positive rate was 10.33%.There were 14 serotypes,with S.Rissen(9 isolates,26.47%)and S.London(8 isolates,23.53%)being domi⁃nant.PFGE typing revealed 31 band patterns and 23 banding pattern clusters of Salmonella,and the similarity ranged from 30.80%to 100.00%,without dominant band patterns.MLST identified 15 sequence typing(ST)types,and S.Ris⁃sen were all ST469 and S.London were all ST155.Salmonella strains exhibited high levels of resistance to tetracycline(44.12%)and ampicillin(35.29%).Thirteen resistance patterns were identified,with 8 multidrug resistant patterns(29.41%).There were 8 classes of 14 resistance genes,with aminoglycoside resistance gene aac(6')-Iaa found in 100.00%of the strains.The highest concordance rate between the resistance phenotype and gene was observed for phen⁃icol antibiotics(97.06%),while there was no concordance between the quinolone resistance phenotype and genes.Con⁃clusions S.Rissen and S.London are the predominant serotypes in market-sold raw livestock meats in Shaoxing City.The PFGE band types of the Salmonella isolates show polymorphism distribution,and MLST are mainly ST469 and ST155.The isolates have high levels of resistance to tetracycline and ampicillin,manifesting multidrug resistance.