Escherichia coli O157:H7, an emerging gastrointestinal pathogen. Results of a one-year, prospective, population-based study

To examine the incidence of Escherichia coli O157:H7 enteric infections in the United States and to evaluate the vehicles of transmission for sporadic cases, we conducted a one-year, population-based study at a large health maintenance organization (HMO) in the Puget Sound area of Washington State. All stool specimens submitted for culture to the HMO laboratory were screened for E coli O157:H7; the organism was identified in 25 (0.4%) of 6485 stool specimens. All patients with E coli O157:H7 identified had diarrhea; 24 patients (96%) had bloody diarrhea. Exposure histories demonstrated that rare ground beef was consumed more often by patients (21%) than by age-matched control subjects (4%) in the week before onset of illness. Raw milk also was consumed by two patients but by none of the control subjects. Incidence rates for laboratory-confirmed enteric infections in the HMO population were as follows: Campylobacter, 50/100,000 person-years; Salmonella, 21/100,000 person-years; E coli O157:H7, 8/100,000 person-years; and Shigella, 7/100,000 person-years. The organism is a more common pathogen in the United States than is generally recognized, and the diagnosis should be considered for patients with suspected enteric infection.     

Sporadic occurrence of hemorrhagic colitis associated with Escherichia coli O157:H7 in Newfoundland.

During a 9-month period in 1984, 113 fecal samples obtained from 92 patients with diarrheal illness were cultured for Escherichia coli serotype O157:H7 to determine the occurrence of this agent in diarrheal illness in Newfoundland. E. coli O157:H7 was isolated in almost pure culture from 12 stool specimens obtained from 7 (15%) of the 47 patients who had grossly bloody diarrhea; none of the 12 yielded any of the usual enteric pathogens. The agent was not isolated from the stool specimens obtained from the remaining 45 patients, who did not have bloody diarrhea. All seven patients whose specimens were positive for E. coli O157:H7 had clinical manifestations typical of hemorrhagic colitis, but the syndrome was clinically suspected and a specific test requested in only two cases. The seven cases were not clustered geographically or temporally, and no common exposure was identified. To determine whether hamburger meat was the source of E. coli O157:H7, 66 samples obtained from various retail outlets were tested; none were found to be positive. Hemorrhagic colitis may be a common disease, and E. coli O157:H7 should be considered as an agent in bloody diarrheal illness.     

Illness outbreak associated with Escherichia coli O157:H7 in Genoa salami

BACKGROUND: An outbreak of Escherichia coli O157:H7 infection was identified in the spring of 1998, with a 7-fold increase in the number of laboratory-confirmed E. coli O157:H7 cases in southern Ontario. This prompted an intensive investigation by local, provincial and federal public health officials. METHODS: Case interviews of 25 people from southern Ontario were conducted using a broad food history and environmental exposure survey. Laboratory investigations involved both case and food sampling. Specimens of foods sold locally and reportedly consumed by those affected were tested. Common suppliers of suspected foods were identified by cross-referencing suppliers' lists with stores frequented by those who fell ill. A case-control study involving 25 cases and 49 age-matched controls was conducted. This was followed by a comprehensive environmental investigation of the meat processing plant identified as the source of the E. coli. RESULTS: Thirty-nine outbreak-related cases occurred between April 3 and June 2, 1998. Of the 36 case specimens tested all were positive for E. coli O157:H7. The case-control study identified Genoa salami as the most probable (odds ratio 8 [confidence interval 2-35]) source of the outbreak. Samples of Genoa salami produced by the most commonly identified supplier later tested positive for E. coli O157:H7, and the pathogen matched the same pulsed-field gel electrophoresis pattern and phage type of the case specimens. INTERPRETATION: Our investigation, which led to a national recall of the brand of dry fermented Genoa salami identified as the source of the outbreak, supports an adherence to stringent manufacturing requirements for fermented meat products. A review of the Canadian standards for fermented meat processing and the effectiveness of their implementation is warranted.     

Preparation of Monoclonal Antibody and Development of Enzyme-linked Immunosorbent Assay Specific for Escherichia coil O157 in Foods

OBJECTIVE: To prepare monoclonal antibodies (MAb) and antisera specific for Escherichia coli (E. coli) O157, and to develop a sandwich enzyme-linked immunosorbent assay (ELISA) to detect E. coli O157 in foods. METHODS: Spleen cells from BALB/c mice immunized with the somatic antigen of E. coli O157:H7 were fused with murine Sp2/0 myeloma cells. The hybridoma cell line specific for E. coli O157 was established after having been subcloned. Antisera specific for E. coli O157 was prepared by intravenous injection into New Zealand rabbits with a stain of E. coli O157:H7. The sandwich ELISA was developed with the polyclonal antibody as the capture antibody and the MAb 3A5 as the detection antibody. The inoculated ground poultry meat and pasteurized milk were tested to confirm efficiency of the method. RESULTS: MAb 3A5 specific for E. coli O157 and O113:H21 belonged to subtype IgM. The ascetic titers of the antibody was 1:1x10(6). No cross-reactivity of the MAb was observed with strains of Salmonella spp, Yersinia enterocolitica, Shigella dysenteriae, etc. The purified polyclonal antibody had a titer of 1:1x10(5) with E. coli O157. The detection limit of this sandwich ELISA was 10(3)-10(4) cfu E. coli O157/mL in pure culture with a high specificity, which was characterized by every non-O157 strain with negative response. With 10h enrichment procedure, E. coli O157:H7 recovered well from inoculated ground poultry meat and pasteurized milk at levels of 0.1 cfu/g and 0.1 cfu/mL. CONCLUSION: MAb 3A5 specific for E. coli O157 and O113:H21 can be produced by immunizing BALB/c mice with a strain of E. coli O157:H7. Then a sandwich ELISA can be developed with the polyclonal antibody as the capture antibody and the MAb 3A5 as the detection antibody. The method is proved to be a sensitive and specific technique to detect low number of E. coli O157 in food.     

Lectins in fruits having gastrointestinal activity: their participation in the hemagglutinating property of Escherichia coli O157:H7.

BACKGROUND: In fruits with therapeutic properties for antidiarrheal and laxative uses, the presence of lectins may be the bioactive properties that interfere with bacterial adhesion, thought to be competition for glycoside signal sites in the attachment. METHODS: This study identifies lectins in crude extracts from fruits such as Tamarindus indica (tamarind), Spontia vulgaris (plum), Psidium guava (guava), Mangifera indica (mango), Cydonia vulgaris (quince), and Crataegus mexicanus (tejocote). To verify the procedures, extracts from Ricinus communis (castor bean), Glycine max (soybean), Phaseolus vulgaris (beans), Vicia fava (fava bean), and Solanum tuberosum (potato) were used as controls for lectin activity. Both sources of lectins were analyzed to determine their participation in the host-parasite interaction, using as a model the hemagglutinating properties of Escherichia coli O157:H7 (EHA). RESULTS: All extracts showed hemagglutination to group O erythrocytes test (HA) with the exception of mango. Two new galactose-specific lectins were identified from tamarind and guava. When analyzed for participation in EHA, only guava lectins inhibited this, while soybean lectin induced hemolysis; as both lectins bind to galactose, it is probable that their recognition occurs in different domains. Sugars involved in the attachment between Escherichia coli O157:H7 and red cells were identified and again, galactose in addition to mannose was found to be related in EHA. On the other hand, guava lectins also agglutinated E. coli O157:H7, perhaps due to the same galactose-specific lectin or to another type of lectin. CONCLUSIONS: In summary, guava has a galactose-specific lectin that prevents adhesion of E. coli O157:H7 to red cells; this lectin is mediated by galactose. Prevention could also be due to their capacity of agglutinating E. coli by guava lectins. Soybean lectin induced hemolysis only when bacteria was present, but not with floating secretions. This finding showed that guava is a source of lectin that can be explored to prevent adhesion of E. coli to epithelial intestinal cells; contrariwise, soya must be studied to see its participation in the uremia caused during E. coli O157:H7 pathogenesis.     

鼠李糖乳杆菌效应蛋白HM0539增强小鼠对大肠杆菌O157:H7肠道感染的抵抗力

目的 探究鼠李糖乳杆菌LGG的效应蛋白HM0539对大肠杆菌O157∶H7肠道感染的预防效果。方法 采用黏附、侵袭实验评价HM0539处理后,大肠杆菌O157∶H7对HT-29细胞的黏附侵袭能力。通过免疫荧光、免疫印迹等方法进一步检测在使用HM0539治疗过程中对HT-29细胞中黏蛋白（MUC2）、紧密连接蛋白（ZO-1）表达的影响;通过动物实验,观察小鼠的生存率及体质量变化,检测攻毒小鼠的肠道病理及肠道屏障功能的改变。结果 HM0539呈浓度依赖性地抑制大肠杆菌O157∶H7黏附和侵袭HT-29,且HM0539的预处理效果优于共同处理（P<0.05）;免疫荧光和免疫印迹等结果显示,HM0539不仅可以明显降低大肠杆菌O157∶H7感染后MUC2的表达水平（P<0.05）,还可显著抑制其对细胞间紧密连接蛋白的破坏（P<0.05）。动物实验结果证 明HM0539可抑制攻毒小鼠的体质量下降（P<0.05）和空肠的损伤;HM0539可抑制大肠杆菌O157∶H7诱导的空肠杯状细胞的破坏（P<0.05）;此外,HM0539可上调攻毒小鼠空肠中的MUC2、ZO-1蛋白的表达（P<0.05）。结论 HM0539可抑制大肠杆菌O157∶H7黏附和侵袭HT-29细胞,而且增强了小鼠对大肠杆菌O157∶H7感染的抵抗力,其机制可能是通过抑制大肠杆菌O157∶ H7破坏黏蛋白和细胞间紧密连接蛋白。     

Analysis on the Epidemiological Characteristics of Escherichia coli O157:H7 Infection in Xuzhou, Jiangsu, China, 1999

Objective:To determine epidemiologic features of an Escherichia coli O157:H7 outbreak occurred in Xuzhou,Jiangsu Province,China in 1999,and assess the incidence of E. coli O157:H7 in diarrhea patients and host animals and its relationship with disease onset,and provide a scientific basis for establishing prevention and control strategies. Methods: Epidemiological,microbiological,and molecular methods were performed to identify risk factors and describe the ecology of E. coli O157:H7 in the environment. Resu...     

检测肠出血性大肠埃希菌O157:H7的环介导等温扩增和PCR法比较

目的建立基于环介导等温扩增(LAMP)技术的肠出血性大肠埃希菌(EHEC)O157:H7快速简便检测方法,并与PCR进行比较。方法针对EHEC O157:H7保守的rfbE基因序列,设计特异性引物,建立LAMP和PCR检测技术并优化其反应条件,比较这两种检测方法的灵敏度、特异性和对实际样品的检测结果。结果成功建立了LAMP和PCR检测体系,灵敏度检测结果显示,LAMP检测限低至10 cfu/ml,PCR检测限为102cfu/ml,LAMP检测灵敏度高于PCR;对39株近源菌进行检测,结果显示,LAMP法仅7株EHEC O157:H7得到阳性结果,非EHEC O157:H7菌株均为阴性,PCR产物则出现非特异性条带,LAMP法特异性比PCR法高。对于32份猪肉样品的检测,LAMP和PCR与常规检测结果一致,3份样品检测阳性。结论 LAMP检测技术的特异性和灵敏度较PCR高,并且操作简便、检测成本低,耗时短,更有望发展成为快速准确检测EHEC O157:H7的有效手段。     

江苏省徐州市分离的大肠杆菌O157:H7菌株携带志贺毒素2型别的变化

目的 研究我国分离的大肠杆菌O157：H7菌株的志贺毒素型别的变化。方法使用针对志贺毒素2及其变种的引物对进行PCR检测、细菌染色体DNA的PstⅠ酶切后的Southern印迹实验和PCR产物的HaeⅢ、RasⅠ酶切分析,以及：PCR产物克隆后的序列分析方法以及致病性大质粒的PstⅠ酶切分析。结果1999年分离自徐州市的人的5株菌均携带slt1、slt2,而2000年从江苏省徐州市患者分离的10株和蜣螂标本分离的4株共计14株大肠杆菌O157：H7菌株仅携带slt2vha毒素基因,其致病性质粒的限制性酶切图谱与1999年的菌株相比也发生了改变。结论鉴于江苏省徐州市1999年的分离的5菌株全部携带slt1和slt2基因,结果提示该地的优势菌型发生了改变,可能当地大肠杆菌O157：H7感染的流行病学特点有关。针对slt2变异基因而设计的引物及其以此为基础进行的限制性片段长度多态性分析的方法对于研究O157：H7菌株的志贺毒素型别的变化能够满足特异性及灵敏性的要求。     

实时荧光PCR同时检测金黄色葡萄球菌和大肠杆菌O157：H7

目的建立改良分子信标一双重实时荧光PCR同时检测金黄色葡萄球菌和大肠杆菌0157：H7,应用于细菌性食物中毒的快速诊断。方法根据GeneBank公布的金黄色葡萄球菌nuc基因序列和大肠杆菌O157：H7rfbE基因序列,设计引物和改良分子信标探针,建立改良分子信标一双重实时PCR检测体系。结果双重荧光PCR反应体系检测151株金黄色葡萄球菌和27株大肠杆菌O157：H7,均出现特异的荧光信号,两种细菌检测互不干扰。对8762份大便、食品等标本进行检测,315份标本金黄色葡萄球菌实时荧光PCR阳性,其中286份金黄色葡萄球菌培养阳性;31份标本大肠杆菌O157：H7实时荧光PCR阳性,其中26份大肠杆菌O157：H7培养阳性。从样品处理到检测结果仅需要时间2h～1d。结论改良分子信标-多重实时荧光PCR检测体系快速、灵敏度高,特异性强,可用于金黄色葡萄球菌和大肠杆菌O157：H7食物中毒的快速诊断和肠道传染病的初筛,为食源性疾病的分子流行病学调查提供新的检测手段。     

大肠杆菌O157∶H7异硫氰酸荧光素标记抗体的制备及评价

目的:制备高效价、高纯度、特异性好、荧光强度高及稳定的抗大肠杆菌O157∶H7 异硫氰酸荧光素(FITC)标记抗体,初步探讨其在大肠杆菌荧光免疫检测试验中的应用。方法：复苏培养E.coli O157∶H7标准菌株,甲醛灭活制备疫苗免疫家兔。4次免疫后,颈动脉采血分离血清,经辛酸-饱和硫酸铵法粗提后应用蛋白亲和层析柱HiTrap Protein G HP进行 gG纯化,借助SDS-PAGE电泳、BCA试剂盒法、间接ELISA法分别对蛋白纯度、蛋白含量及抗体效价进行测定。应用不同FITC与蛋白量比值以及不同标记反应条件对多克隆抗体进行标记。比较荧光抗体F485/535,结合差异性显著分析对FITC与蛋白量比值及反应条件进行合
理选择,应用标记抗体与E.coli O157∶H7和金黄色葡萄球菌混合菌液反应验证标记效果。结果：HiTrap Protein G进行E.coli O157∶H7多克隆抗体纯化的最佳纯化方法为35%、100%二梯度洗脱,制备抗体效价为1∶25　600,与沙门氏菌、阴沟肠杆菌等8种肠杆菌无交叉反应,最佳FITC与蛋白量比值为1∶10,最佳标记反应条件为20℃、2 h。由最佳条件制得的荧光抗体与E.coliO157∶H7反应明显 ,强荧光连续照射15 min后仍显示高亮度荧光反应,且不与金黄色葡
萄球菌反应。结论：本实验首次制备出纯度高、荧光强度高、持续时间长的E.coli O157：H7 FITC标记多克隆抗体,为E.coli O157：H7荧光免疫检测方法的建立完成了关键步骤。
     

商丘市、济源市腹泻患者、家禽、家畜粪便中E.coli O157:H7的鉴定

目的：对商丘市、济源市腹泻患者、家禽、家畜粪便中首次分离的E.coliO157:H7进行生物学特性等方面的研究。方法：采集疫区患者，外环境，家畜和家禽粪便标本1895份，采用mEC肉汤增菌，胶体金免疫卡快速测定法，免疫磁珠集菌法，CHROMAGAR-O157：H7菌株，在CHROMAGAR-O157：H7显色培养基生长形态，颜色，生化反应出现多样化，rfbO157,stx2,hlyA,eaeA基因检测均阳性的有58株，stx2阳性1株，eaeA阳性4株，72株无毒力基因。结论：为本省实验室诊断E.coliO157:H7提供了理论依据；不同种类的家禽，家畜分离的产毒菌株比例差别显著，以波尔山羊最为突出；为今后在制定对该菌的诊断标准，传染源的追踪和控制及细菌毒力学等方面的研究提供了重要线索。     

肠出血性大肠埃希菌O157：H7的分布及特征

目的了解H市外环境（食品、生活污水及菜地土壤）中肠出血性大肠埃希菌O157∶H7的分布与特性。方法用免疫磁珠富集法进行O157：H7分离;按《全国食品污染物监测相关实验室手册》（细菌学部分）及相关国家标准鉴定分离菌株;标准血清分型;PCR法测定菌株SLT1,SLT2,ereA,hly毒素基因;纸片琼脂扩散（K-B）法测定菌株耐药性。结果自H市外环境标本（食品、生活污水、菜地土壤）检出O157：H7共15株,检出率1.42%～4.34%,鸡肉与生活污水检出率高;农贸市场食物中O157：H7的检出率（2.25%）高于超市（0.56%）;它们中有93.33%（14/15）是携带SLT1、SLT2、eae、hly毒力基因的高致病菌株;食源性O157：H7耐药性严重,耐药菌株多,仅对哌拉西林、亚胺培南敏感。结论H市外环境有O157：H7分布,且检出的多是高致病性强毒菌株,应警惕其流行造成感染的潜在危险。     

南平市2007-2009年食源性致病菌污染状况

目的了解南平市市售食品中食源性致病菌污染状况及分布和高危食品种类。方法在全国食品污染物监测网与食源性疾病监测网控制体系下,2007-2009年采集4个监测点内的7大类市售食品共计208份,对沙门菌、单核细胞增生性李斯特菌、O157∶H7出血性大肠埃希菌、金黄色葡萄球菌以及副溶血性弧菌5种食源性致病菌进行监测分析。结果 208份食品样品中,分离出目标菌38株,总检出率18.27%。其中生肉类、水产品检出率最高,分别为38.46%（15/39）和73.08%（19/26）,其次为速冻米面,检出率20.00%（4/20）。监测的5种食源性致病菌均有检出,各类食品中沙门菌和副溶血性弧菌的检出率最高,分别为33.33%和50.00%;O157∶H7检出率为0.68%;金黄色葡萄球菌及单核细胞增生性李斯特菌检出率为4.22%和1.79%。O157∶H7经毒力检测存在产志贺毒素。结论通过连续3年对南平市市售食品中食源性致病菌的主动监测,掌握了食源性致病菌的污染状况、高危食品以及5种食源性致病菌在不同食品中的分布情况。     

肠出血型大肠埃希菌免疫PCR检测方法的建立

目的建立检测肠出血型大肠埃希菌O157：H7的免疫PCR技术,确定该方法的灵敏度和特异性。方法链亲和素桥联生物素化的二抗和双链DNA指示分子,构建桥联系统,进而建立免疫PCR技术,通过PCR扩增指示分子检测O157：H7。结果免疫-PCR技术最少可检测到10 CFU/ml的纯培养菌,灵敏度较ELISA提高103倍,非O157：H7菌株检测结果均为阴性。结论免疫-PCR技术具有较高的灵敏度和特异性,操作简便、快速,可作为肠出血型大肠埃希菌O157：H7的检测方法。     

网状分枝扩增技术快速检测大肠埃希菌O157∶H7及其他产志贺样毒素大肠埃希菌

目的：建立一种简便、快速、灵敏和特异的检测食品和临床标本中大肠埃希菌O157∶H7及其他产志贺样毒大肠埃希菌(STEC)的方法。方法：设计并合成了检测志贺毒素2(stx2)基因特异的环形探针和捕获探针，确定网状分枝扩增方法（RAM）的灵敏度；含有stx2基因的不同血清型的菌株包括O46∶H38、O22∶H8 、O111∶NM，用于RAM特异度的测定。用RAM检测所有分离的菌株，并进一步对瞬时RAM进行研究。结果：RAM最低能检测10个拷贝的stx2合成靶基因和临床分离的菌株，表明RAM与PCR具有一样的灵敏度。特异度的测定结果表明不同血清型的大肠埃希菌均为stx2阳性，而非致病性大肠埃希菌ATCC23716则为阴性。在32株菌株中，28株细菌含有stx2基因，其余则为阴性， 与PCR检测结果100%一致。瞬时RAM结果也表明最低能检测10个细菌，检测信号的出现依赖于样品的浓度。 结论：RAM的简便和等温扩增特点可替代PCR检测各种标本中大肠埃希菌O157∶H7和STEC。     

Infections with Escherichia coli O157:H7 in Washington State. The first year of statewide disease surveillance

In 1987, Washington became the first state to require that infection with Escherichia coli serotype O157:H7 be reported. In the first year of surveillance, 93 cases were reported, yielding an annual incidence of 2.1 cases per 100,000 population. The median age of case patients was 14 years (range, 11 months to 78 years), with the highest attack rate among children younger than 5 years (6.1 cases per 100,000 population per year). Bloody diarrhea was present in 95% of reported cases, 12% of patients developed either hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura, and one patient died. Suspected secondary cases were seen in 5% of households. Fifty-six (60%) cases occurred during June through September, as did 73% of the cases of hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura. Cases reported during the summer months were more likely than cases reported at other times of the year to be in children younger than 10 years. Medications, including antimicrobial medications, did not influence the duration of symptoms, nor did they appear to alter the risk of developing hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura. This newly established surveillance system in Washington demonstrates that E coli O157:H7 is an important and common cause of bloody diarrhea in the United States.     

Risk of hemolytic uremic syndrome after antibiotic treatment of Escherichia coli O157:H7 enteritis: a meta-analysis

Context  The use of antibiotics for treatment of Escherichia coli O157:H7 infection has become controversial since a recent small study found that it may increase the risk of hemolytic uremic syndrome (HUS). However, other larger studies have reported a protective effect or no association. Objective  To determine whether antibiotic therapy for E coli O157:H7 enteritis increases the risk of HUS. Data Sources  PubMed and MEDLINE computer searches were performed for studies published from January 1983 to February 2001 using the key words hemolytic uremic syndrome, risk factor, antibiotics, and Escherichia coli O157:H7. Reference lists of relevant publications were reviewed, and 12 experts in the field were contacted to identify additional reports. No language restrictions were applied to the search. Study Selection  Studies were included if they reported a series of patients with documented E coli O157:H7 enteritis, some of whom developed HUS; had clear definitions of HUS; and had adequate data delineating the relationship between antibiotic therapy and the occurrence of HUS. Nine of the 26 identified studies fulfilled these criteria. Data Extraction  Two authors (N.S. and A.S.) independently reviewed each report identified by the searches and recorded predetermined information relevant to the inclusion criteria. A pooled odds ratio was calculated using a fixed-effects model, with assessment of heterogeneity among the studies. Data Synthesis  The pooled odds ratio was 1.15 (95% confidence interval, 0.79-1.68), indicating that there does not appear to be an increased risk of HUS with antibiotic treatment of E coli O157:H7 enteritis. Incomplete reporting of data in individual studies precluded adjustment for severity of illness. Conclusion  Our meta-analysis did not show a higher risk of HUS associated with antibiotic administration. A randomized trial of adequate power, with multiple distinct strains of E coli O157:H7 represented, is needed to conclusively determine whether antibiotic treatment of E coli O157:H7 enteritis increases the risk of HUS.      

江苏省113株大肠杆菌O157:H7的扩增片段长度多态性分析

目的:分析江苏省不同地区和年代分离的Escherichia coli O157:H7(E. coli O157:H7)之间的同源性?方法:用扩增片段长度多态性(amplified fragment length polymorphism,AFLP)分析法对113株 E. coli O157:H7菌株进行分子分型,采用软件BioNumerics Version 4.0对分型数据进行处理和分析?结果:113株E. coli O157:H7共分37个型别,不同来源的菌株存在相同的基因型别,不同的地区和物种之间存在着相互传播?结论:AFLP可以用于对不同来源的E. coli O157:H7进行分子分型?     

O157:H7大肠杆菌外膜蛋白对小鼠免疫保护作用的实验研究

目的　研究经不同免疫途径 ,O1 5 7:H7大肠杆菌外膜蛋白 (OMP)对小鼠接受致死剂量该菌攻击后的免疫保护作用。方法　用外膜蛋白分别通过鼻腔、口腔和皮下途径对雌性BALB/c小鼠免疫 3次 ,采用ELISA测定血、阴道冲洗液和粪便内抗体水平 ;用Western 印迹方法分析诱导小鼠产生抗外膜蛋白特异性抗体的抗原 ;用致死剂量O1 5 7:H7大肠杆菌活菌经口腔攻毒 ,观察记录动物的发病与死亡情况 ;观察受染动物器官病理变化。结果　ELISA结果表明 ,经鼻腔与口腔免疫 ,能有效诱导抗外膜蛋白IgA和IgG免疫应答 ,鼻腔免疫更为有效。经皮下免疫仅能诱导血中产生高水平的特异性IgG抗体。攻毒后 ,鼻腔和口腔免疫组小鼠存活率明显高于对照组 (86 7%比 4 0 % ,P <0 0 1和 73 3%比 4 0 % ,P <0 0 5 ) ,鼻腔免疫组更高 (86 7%比 73 3% ,P <0 0 5 )。而皮下免疫组存活率甚至低于对照组 (1 3 3%比 4 0 % ,P <0 0 5 )。结论　O1 5 7:H7大肠杆菌外膜蛋白对实验小鼠的该菌株致死剂量攻击有较强的保护作用。鼻腔免疫途径为O1 5 7:H7大肠杆菌外膜蛋白诱导机体产生免疫保护的最佳途径