2021-2022年浙江省绍兴市市售畜禽肉中致泻性大肠埃希菌耐药性与同源性分析

Drug resistance and homology of diarrheagenic Escherichia coli from livestock and poultry meats in markets in Shaoxing,Zhejiang,2021−2022

目的了解2021—2022年浙江省绍兴市市售畜肉和禽肉中致泻性大肠埃希菌(DEC)的耐药表型和同源性。方法2021年3月至2022年11月采集绍兴市所辖区内农贸市场、超市和餐饮店畜禽肉420份,对样本中的DEC进行分离鉴定。采用微量肉汤稀释法测定分离株对13种抗生素的耐药性,使用脉冲场凝胶电泳(PFGE)技术对分离株进行分子分型并采用BioNumerics7.6软件进行聚类分析。结果420份畜禽肉样本(畜肉112份、禽肉308份)有72份阳性,总检出率为17.14%(72/420),其中畜肉DEC检出率为19.64%(22/112),禽肉DEC检出率为16.23%(50/308)。共分离到77株DEC,其中畜肉源24株,禽肉源53株,77株DEC共分为3种型别,其中肠聚集性大肠埃希菌(EAEC)占92.21%(71/77),肠致病性大肠埃希菌(EPEC)占5.19%(4/77),产志贺毒素大肠埃希菌(STEC)占2.60%(2/77)。77株DEC对四环素耐药率最高,为76.62%(59/77),对氨苄西林、氯霉素、甲氧苄啶/磺胺甲恶唑的耐药率分别为67.53%(52/77)、61.04%(47/77)、57.14%(44/77)。发现1株EAEC对碳青霉烯类药物(亚胺培南)耐药。77株DEC获得46种耐药谱,多重耐药菌株占70.13%(54/77)。禽肉源分离株对头孢唑林(χ^(2)=9.403,P=0.002)、头孢噻肟(χ^(2)=7.721,P=0.005)、庆大霉素(χ^(2)=11.422,P<0.001)、萘啶酸(χ^(2)=10.685,P=0.001)、环丙沙星(χ^(2)=6.340,P=0.012)耐药率均高于畜肉源分离株,差异有统计学意义。禽肉源分离株多重耐药菌株(≥5类)占比高于畜肉源分离株,差异有统计学意义(χ^(2)=7.423,P=0.006)。76株DEC获得75种PFGE带型,72个带型簇。70株EAEC获得69种PFGE带型,66个带型簇;4株EPEC获得4种PFGE带型,4个带型簇;2株STEC获得2种PFGE带型,2个带型簇。结论绍兴市市售畜禽肉源DEC优势型别为EAEC,分离株对常见药物的耐药率较高,耐药谱广泛,多重耐药现象普遍存在。分离株的PFGE带型呈多态性分布,亲缘关系较低。畜牧业应加强对抗生素的使用管理,加强DEC的耐药性监测,防控耐药菌的传播。

Objective To explore the drug-resistance phenotype and homology of diarrheagenic Escherichia coli(DEC)isolated from livestock and poultry meats in Shaoxing,Zhejiang province,from March 2021 to November 2022.Methods A total of 420 livestock and poultry meat samples were collected from farm produce markets,supermarkets and restaurants in Shaoxing during 2021−2022 for DEC isolation and identification.The drug susceptibility tests to 13 kinds of antibiotics were conducted for the isolates by micro broth dilution method.The molecular typing of the isolates was performed by pulsed-field gel electrophoresis(PFGE)and the clustering analysis was performed with software BioNumerics 7.6.Results In 420 livestock and poultry meat samples,72 were positive for DEC,the positive rate was 17.14%(72/420).In 112 livestock meat samples and 308 poultry meat samples,22 and 50 were positive for DEC,respectively.The positive rates were 19.64%and 16.23%.A total of 77 strains of DEC were isolated,including 24 strains from livestock meat and 53 from poultry meat.The 77 strains of DEC could be classified into three types,including 71 strains of enteroaggregative Escherichia coli(EAEC)(92.21%),4 strains of enteropathogenic E.coli(EPEC)(5.19%),2 strains of Shiga toxin-producing E.coli(STEC)(2.60%).The resistance rate to tetracycline was highest(76.62%,59/77),and the resistance rates to ampicillin,chloramphenicol,trimethoprim/sulfamethoxazole were 67.53%(52/77),61.04%(47/77)and 57.14%(44/77),respectively.One EAEC strain was found to be resistant to carbapenems(imipenem).Forty-six drug resistance spectrums were found in the 77 strains,and multi-drug resistance strains accounted for 70.13%(54/77).The resistance rates of poultry meat strains to cefzaolin(χ^(2)=9.403,P=0.002),cefotaxime(χ^(2)=7.721,P=0.005),gentamicin(χ^(2)=11.422,P<0.001),nalidixicacid(χ^(2)=10.685,P=0.001)and ciprofloxacin(χ^(2)=6.340,P=0.012)were higher than those of livestock meat isolates,the differences were significant.The multi-drug resistant rate(≥5 classes)in poultry meat strains was higher than that in livestock meat strains,the difference was significant(χ^(2)=7.423,P=0.006).Using pulsed field gel electrophoresis(PFGE),76 strains of DEC were divided into 75 band types and 72 band clusters.70 strains of EAEC were divided into 69 band types and 66 band clusters.4 strains of EPEC were divided into 4 band types and 4 band clusters and 2 strains of STEC were divided into 2 band types and 2 band clusters.Conclusion The predominant type of DEC isolated from livestock and poultry meat in Shaoxing was EAEC.The resistance rate of the isolates to common drugs was high,and the drug resistance spectrum was wide.The prevalence multi-drug resistance was common.The PFGE band type of the isolates showed polymorphism distribution and low genetic relationship.It is necessary for animal husbandry to strengthen the management of the use of antibiotics and improve drug resistance surveillance to prevent and control the spread of drug-resistant DEC.