即食鸭制品大肠埃希菌污染状况、毒力基因和耐药特征分析

为探明即食鸭制品中大肠埃希菌污染情况以及大肠埃希菌毒力基因状况和耐药特征,分别从浙江、上海、福建、江苏、广东、北京、黑龙江、内蒙古、贵州、湖北和四川11个省份采集即食鸭制品491份,用于大肠埃希菌的分离;采用VITEK 2 Compact全自动细菌鉴定及药敏分析系统对分离株进行鉴定和开展耐药表型分析,PCR扩增毒力基因、耐药基因和Ⅰ型整合酶基因。结果表明:从491份即食鸭制品中分离大肠埃希菌109株,检出率为22.20%。大肠埃希菌分离株毒力基因esc V的检出率最高,达7.34%,其次为pic,达6.42%,ipa H和aggR均为3.67%,stx2为2.75%,eae、lt和stx1均为1.83%。大肠埃希菌对磺胺类的复方新诺明和青霉素类的氨苄西林耐药性较高,分别为63.30%和61.47%;耐药数≥3的菌株比例为60.55%,最高可同时对12种抗生素耐药,占比为2.75%。相应地,磺胺类药物耐药基因sul Ⅰ和sul Ⅱ检出率最高,分别为100%和88.07%,喹诺酮类基因qnrA和qnrS、氨基糖苷类基因aadA1和mecC的检出率也均在35%以上。24株产超广谱β-内酰胺酶(ESBLs)的大肠埃希菌携带的β-内酰胺耐药基因CTX-M、TEM、SHV、CTX-M-1、CTX-M-2、CTX-M-9和CTX-M-25的检出率分别为100.00%、95.83%、4.17%、66.67%、12.50%、75.00%和4.17%。20株Ⅰ型整合子阳性大肠埃希菌中7株携带基因盒插入片段,其中2株大肠埃希菌Ⅰ型整合子基因盒插入的为dfrA1-aadA1,4株为dfrA12-aadA2,另1株为aadA22。由此表明,即食鸭制品中污染的大肠埃希菌携带有一定的毒力基因并具有耐药性。

Virulence genes and drug resistance characteristics of Escherichia coli in ready-to-eat duck products

To analyze the contamination of E. coli in ready-to-eat duck products, the virulence gene status and drug resistance characteristics of E. coli, 491 samples of ready-to-eat duck products were collected from 11 provinces of Zhejiang, Shanghai, Fujian, Jiangsu, Guangdong, Beijing, Heilongjiang, Inner Mongolia, Guizhou, Hubei and Sichuan for the isolation of E. coli. The VITEK 2 COMPACT analysis system was used to identify the isolates and analyze the drug resistance profile. The virulence genes, drug-resistant genes and class I integrase genes were amplified by PCR. The results showed that a total of 109 strains of E. coli were isolated from 491 ready-to-eat duck products, and the detection rate was 22.20%. The detection rate of escV was the highest (7.34%), followed by pic(6.42%), ipaH and aggR(3.67%), stx2 (2.75%), eae, lt and stx1(1.83%). Escherichia coli showed high resistance to ampicillin of cotrimoxazole and penicillins, which were 63.30% and 61.47%, respectively. The proportion of strains with drug resistance ≥3 was 60.55%, and the highest resistance to 12 antibiotics at the same time was 2.75%. Corresponding sulfonamine-resistant genes had the highest detection rates at 100.00% and 88.07%, respectively, and the detection rates of quinolone genes qnrA and qnrS, aminoglycoside genes aadA1 and mecC were also above 35%. The detection rates of β-lactam resistant genes CTX-M, TEM, SHV, CTX-M-1, CTX-M-2, CTX-M-9 and CTX-M-25 in 24 extended-spectrum β-lactamases (ESBLs)-producing Escherichia coli strains were 100.00%, 95.83%, 4.17%, 66.67%, 12.50%, 75.00% and 4.17%, respectively. Seven strains of E. coli among 20 integron positive Ⅰ carried genes inserted elements, among them 2 strains of E. coli type Ⅰ integron genes inserted for dfrA1-aadA1, 4 strains for dfrA12-aadA2, another strain for aadA22. It was indicated that the Escherichia coli contaminated with ready-to-eat duck products had certain virulence genes and drug resistance.