食源性产超广谱β-内酰胺酶的致泻性大肠埃希菌的毒力基因分型及耐药分析

Virulence genotyping and drug resistance analysis of food-borne ultraspectrumβ-lactamase-producing diarrheal Escherichia coli

目的分析食源性产超广谱β-内酰胺酶(ultraspectrumβ-lactamase,ESBLs)的致泻性大肠埃希菌(diarrheagenic Escherichia coli,DEC)的毒力基因分型特征及耐药情况。方法以苏州市食源性疾病监测中通过聚合酶链式反应(polymerase chain reaction,PCR)进行毒力基因检测并分型的285株DEC为研究对象,采用微量肉汤法对29种抗菌药进行药敏试验,其中头孢噻肟/克拉维酸(CTX/C)及头孢他啶/克拉维酸(CAZ/C)用于检测其是否产ESBLs,其余27种抗生素根据其最低抑菌浓度(minimal inhibitory concentration,MIC)判定敏感(S)、中介(I)及耐药(R)。采用χ^(2)检验或Fisher精确概率法比较产ESBLs的DEC与非产ESBLs的DEC间的耐药差异。结果苏州市检出的285株DEC中,产ESBLs的DEC为47株,占比16.49%(47/285),毒力基因型以肠道聚集性大肠埃希菌(enteroaggregative Escherichia coli,EAEC)为主(38.30%,18/47)。总耐药率为97.87%(46/47),对23种抗生素产生耐药,对氨苄西林(ampicillin,AMP)、头孢唑啉(cefazolin,CFZ)、头孢呋辛(cefuroxime,CXM)、头孢噻肟(cefotaxime,CTX)、头孢噻呋(ceftiofur,CEF)、四环素(tetracycline,TET)、萘啶酸(nalidixic acid,NAL)、甲氧苄氨嘧啶/磺胺甲噁唑(trimethoprim/sulfamethoxazole,SXT)的耐药率较高,对头孢他啶/阿维巴坦(CZA)、碳青霉烯类药物(IPM、MEM、ETP)及替加环素(tigacycline,TIG)不耐药;在与非产ESBLs的DEC比较中发现对AMP、氨苄西林/舒巴坦(ampicillin/sulbactam,AMS)、头孢唑啉(cefazoline,CFZ)等13种抗菌药的耐药率存在统计学差异(P<0.05)。产ESBLs的DEC多重耐药率为89.36%(42/47),远高于非产ESBLs的DEC的48.74%(116/238)。产ESBLs的DEC最多见是耐6种抗生素(MDR6),最常见的多重耐药谱为AMP-CFZ-CXM-CTX-CEF-NAL。结论食源性产ESBLs的DEC耐药情况及多重耐药形势均较严峻,应引起公共卫生监测的重视。

Objective To analyze the virulence genotyping and drug resistance of diarrheagenic Escherichia coli(DEC)from foodborne ultraspectrumβ-lactamase(ESBLs).Methods The 285 strains of diarrheic Escherichia coli from foodborne disease surveillance in Suzhou were tested by polymerase chain reaction(PCR)virulence gene detection and typing,and 29 antimicrobial drugs were tested by microbroth method[minimal inhibitory concentration(MIC)method].Among them,cefotaxime/clavulanate(CTX/C)and ceftazidime/clavulanate(CAZ/C)were used to detect whether they produced ESBLs.The other 27 antibiotics were identified as sensitive(S),intermediate(I)and resistant(R)according to their minimum inhibitory concentration(MIC).The difference of drug resistance between ESBLS-producing DEC and non-ESBLS-producing DEC was compared byχ^(2) test or Fisher exact probability method.Results Among the 285 DECs detected in Suzhou,47 DECs produced ESBLs,accounting for 16.49%(47/285),and the predominant virulence genotype was enteroaggregative Escherichia coli(EAEC)(38.30%,18/47).The total drug resistance rate was 97.87%(46/47),with resistance to 23 kinds of antibiotics.The drug resistance rate to ampicillin(AMP),cefazolin(CFZ),cefuroxime(CXM),cefotaxime(CTX),ceftiofur(CEF),tetracycline(TET),nalidixic acid(NAL),trimethoprim/sulfamethoxazole(SXT)was high.CZA,carbapenems(IPM,MEM,ETP)and tigacycline(TIG)are not resistant;Compared with non-ESBLS-producing DEC,there were statistically significant differences in the resistance rates to 13 antimicrobials,including AMP,ampicillin/sulbactam(AMS)and cefazoline(CFZ)(P<0.05).The multiple drug resistance rate of ESBLS-producing DEC was 89.36%(42/47),which was much higher than that of non-ESBLS-producing DEC(48.74%)(116/238).Decs producing ESBLs were resistant to up to 6 antibiotics(MDR6),and the most common multi-drug resistance spectrum was AMP-CFZ-CXM-CTX-CEF-NAL.Conclusion DEC drug resistance and multiple drug resistance of foodborne ESBLs are serious,which should be paid attention to by public health surveillance.