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目的了解我国食品中分离的110株大肠埃希菌O157的耐药及脉冲场凝胶电泳(PFGE)分子分型特征,完善我国食品中大肠埃希菌O157菌株特征的基础信息,为该菌的风险评估提供依据。方法使用琼脂稀释法对确认的110株大肠埃希菌O157进行药敏试验,完成耐药特征的分析。参照美国疾病预防控制中心PulseNet试验方法,对110株大肠埃希菌O157,运用XbaⅠ酶进行酶切并完成PFGE分析,利用BioNumerics软件对分离株的指纹图谱进行聚类分析。结果 1110株菌中,43株菌至少对一种抗生素有抗性。耐药率最多的前三种抗生素依次是四环素(30.0%,33/110),磺胺甲恶唑(29.1%,32/110),萘啶酸(26.4%,29/110);2一共有24个耐药谱,耐两种以上抗生素的菌株有34株,耐3种以上抗生素的多重耐药菌株有32株。最常见的三种耐药谱依次是SMX(6),AMP-NAL-SMX-SXT-TET(6),AMP-CHL-NAL-SMX-SXT-TET(4)/AMP-SMX-SXT-TET(4)/TET(4);3大肠埃希菌O157非H7(O157∶hund)对所测试的抗生素的耐药率明显高于大肠埃希菌O157∶H7(χ2=72.010 P<0.05)。其中37株携带了志贺毒素基因的大肠埃希菌O157∶H7仅对磺胺甲恶唑(2.7%,1/37)、萘碇酸(2.7%,1/37)有耐药,没有多重耐药菌株;4通过不同种类食品中大肠埃希菌O157菌株耐药率比较发现,从生猪肉、生禽肉中分离的菌株耐药率相对高于其他食品种类;5PFGE分子分型研究显示菌株具有基因多态性,且可以很好将大肠埃希菌O157非H7和大肠埃希菌O157∶H7菌株区分开。结论我国食品中分离的大肠埃希菌O157耐药现象严重。我们应加强养殖环节和零售环节食源性致病菌,特别是大肠埃希菌O157(包括产志贺毒素大肠埃希菌O157)菌株药敏特征的监测,探明食品与养殖环节菌株耐药的传播关系,并为国家制定科学的养殖业抗生素用药提供依据。
OBJECTIVE To understand the molecular typing characteristics of resistant and pulsed-field gel electrophoresis (PFGE) of 110 strains of Escherichia coli O157 isolated from food in China and to improve the basic information of Escherichia coli O157 in China. Provide a basis for risk assessment. Methods The agar dilution method was used to determine the susceptibility of 110 strains of Escherichia coli O157. The drug resistance characteristics were analyzed. According to the PulseNet test of the U.S. Centers for Disease Control and Prevention, 110 Escherichia coli O157 strains were digested with XbaⅠ enzyme and analyzed by PFGE. The fingerprints of the isolates were analyzed by using BioNumerics software. Results Among 1110 strains, 43 strains were resistant to at least one antibiotic. The first three antibiotics with the highest resistance rates were tetracycline (30.0%, 33/110), sulfamethoxazole (29.1%, 32/110) and nalidixic acid (26.4%, 29/110) A drug resistance spectrum, resistant to two or more antibiotics 34 strains of strains, resistant to more than three kinds of antibiotic resistant strains 32 strains. The three most common drug resistance profiles were followed by SMX (6), AMP-NAL-SMX-SXT-TET (6), AMP- CHL-NAL- SMX- SXT- TET (4) / AMP- SMX- SXT- TET (4) / TET (4); 3 The resistance of Escherichia coli O157 non-H7 (O157:hund) to the tested antibiotics was significantly higher than that of Escherichia coli O157: H7 (χ2 = 72.010 P <0.05). Among them, 37 strains of Escherichia coli O157: H7 carrying Shiga toxin gene were resistant to sulfamethoxazole (2.7%, 1/37) and naphthoic acid (2.7%, 1/37) Drug strains; 4 through different types of food Escherichia coli O157 strains drug resistance rate comparison found that isolated from raw pork, raw poultry meat strains resistant rate is relatively higher than other food species; 5PFGE molecular typing studies have shown that the strains have Gene polymorphism, and it is well possible to distinguish Escherichia coli O157 non-H7 from Escherichia coli O157: H7 strain. Conclusion Escherichia coli O157 isolated in our country has a serious drug resistance. We should step up the monitoring of the susceptibility characteristics of food-borne pathogenic bacteria in the breeding and retail sectors, in particular the strains of Escherichia coli O157 (including Shiga toxin-producing Escherichia coli O157), and identify the strains that are resistant to food and aquaculture strains And provide the basis for the state to formulate a scientific antibiotic drug for aquaculture.