厦门市水产品中首次检出O157:H7大肠杆菌

目的：调查我市水产品中O157大肠杆菌的污染情况，为防治工作提供依据。方法：用VIDAS （E.coli O157)试条及E.coli O157检测卡对样品进行初筛，初筛阳性的样品再进行分离培养鉴定。结果：26份水产品中检出2株O157：H7大肠杆菌，检出率7．69％。结论：我市部分水产品中存在O157：H7大肠杆菌的污染，防治工作中应引起足够的重视。     

大肠杆菌O157:H7感染者血清β2-MG变化的研究

目的：通过检测血清β2-MG，分析E．coli O157：H7感染的HC、HUS病人肾功能的损伤情况，为该病的诊断和治疗提供科学依据。方法：对E．coli O157:H7感染的25例HC病人用RIA法检测血清β2-MG，并做追踪观察，对31例HUS病人、36例非E．coli O157:H7感染的腹泻病人以及30例健康人群同时检测血清β2-MG进行比较，并对HC病人血清β2-MG与血液的其他指标进行分析。结果：HC病人、HUS病人、其他腹泻病人及健康人群血清中β2-MG的浓度超过正常值分别为100．0％、100．0％、75．0％和13．3％，平均浓度分别为3．14、11．27、2．75和1．70mg／L。HUS病人及健康人群血清β2-MG与Cr有明显的直线相关关系，连续观察发现HC病人血清β2-MG浓度逐渐下降，无一例发展成为HUS病例。结论：通过检测E．coli O157:H7感染的腹泻病人血清β2-MG并与其他各组人群进行比较发现，HC病人的肾脏受到一定的损伤但在不断的恢复，HUS病人较为严重。合理治疗HC病例，可以减少HUS病例的发生，通过对E．coli O157:H7感染的疑似病例检测β2-MG对于观察病情，制定治疗方案都有一定的意义。     

O157大肠杆菌溶原性噬菌体的初步探讨

[目的]探讨E．coli O157携带噬菌体的情况及噬菌体特性。[方法]从3种血清型E．coli O157菌株中分离筛选噬菌体，并分别从O157：H7和O157：NM检出的噬菌体中各筛选出5株对同源菌进行裂解试验。[结果]3种不同血清型的E．coli O157携带噬菌体的检出率O157：H7为29．9％，对同源菌的裂解率为75．0％；O157：NM检出率为17．3％，对同源菌的裂解率为23．1％；O157：H7为8．1％。[结论]3种不同血清型的E．coli O157均携带温和噬菌体，裂解力较差，噬菌斑均为磨玻璃状，符合前噬菌体的特性。     

生果、蔬中大肠杆菌O157:H7荧光定量PCR检测方法的评估及改进

目的：评估污染风险较高的6种生果、蔬中E．coli．O157：H7的PCR检测情况，以及初步探讨其机理和改善措施。方法：采用添加标准菌株，比较荧光定量PCR检测方法和传统分离培养法的检出情况，然后在PCR反应体系中分别添加PVPP、脱脂奶粉、BSA等物质，比较检出灵敏度的改善情况。结果：除绿豆芽和青椒外，PCR检测方法和传统分离培养法均能在1cfu／10g、10cfu／10g、100cfu／10g的接种浓度上检出阳性，对于绿豆芽和青椒，荧光定量PCR检测方法在1cfu／10g接种浓度上未检出，分离培养法在10cfu／10g、100cfu／10g两个接种浓度上均未检出。添加脱脂奶粉和BSA后，绿豆芽和青椒样品在1cfu／10g的接种浓度上检出阳性，且在该浓度上其他样品的检出频率均有一定提高。PVPP对PCR体系改善不明显。结论：在生果、蔬中E．coli．O157：H7检测中，荧光定量PCR检测方法比传统分离培养法灵敏度更高。脱脂奶粉和BSA可以用于改善生果、蔬中E．coli．O157：H7的荧光定量P（聚检测体系，提高检出率和检测灵敏度。     

大肠杆菌O157:H7的分离鉴定及应用复合PCR法同时检测其三个毒力因子

[目的]对驻滇部队感染性腹泻患者、猪和污水进行大肠杆菌O157：H7(E O157：H7)的分离鉴定。[方法]用O157免疫磁珠富集后，接种S-MAC琼脂平板培养，用MUG试验初筛，VlATEK32全自动微生物鉴定仪鉴定，应用复合PCR法同时检测其三个毒力因子。[结果]从腹泻患者和猪中检出E coli O157：H7，该菌具有三个毒办因子。[结论]云南战区部队存在E coli O157：H7感染。复合PCR法的建立，为腹泻研究领域的病原学监测和流行病学调查提供了新手段。     

睢县出血性大肠杆菌O157:H7监测结果分析

目的通过三年的监测,发现E．coli O157：H7感染性腹泻的分布特征、临床特点、家畜、家禽的带菌状况及外环境污染程度。方法用O157特异性筛查方法进行病原体分离培养,应用分子生学、微生物学、生化学技术进行病人、家畜、家禽的病原学分离、培养、毒素因子测定。结果2000年—2002年从2541份标本中检出E．coli O157：H7199株,其中76株具有毒素基因;显示有5个毒素因子组合型。结论E．coli O157：H7是引起发病的主要致病菌,发病率的高低与家畜家禽的带菌相一致。     

漳州市首次检出O157：H7大肠杆菌

目的：建立食品污染微生物监测点，调查O157：H7大肠杆菌在生肉类食品中污染状况。方法：采用E.Coli O157：H7检测卡对样品初筛，对阳性样品再进行分离培养鉴定。结果：从生猪肉和生羊肉中分离出2株O157：H7大肠杆菌，生肉类食品检出率3．7％。结论：首次证实了漳州市有O157：H7大肠杆菌的存在，运物性食品是该菌感染人类的主要来源，应引起有关部门高度重视。     

徐州市大肠杆菌O157∶H7感染性腹泻爆发因素分析

目的研究O157∶H7感染性腹泻疫情爆发与腹泻病人、宿主动物、苍蝇、食品携带(污染)O157∶H7状况的相关程度。方法调查1999—2011年O157∶H7感染性腹泻疫情资料,采集疫情爆发点和监测点腹泻病人、宿主动物粪便标本和苍蝇、食品标本分离菌株。采用趋势χ2检验和Spearman’s等级相关进行统计分析。结果腹泻病人、宿主动物粪便标本、苍蝇、食品带菌连续性监测结果证实了其与O157∶H7感染性腹泻爆发的关系。结论江苏省徐州市O157∶H7感染性腹泻爆发与腹泻病人带菌率、苍蝇带菌率、食品带菌率关联强度大。苍蝇与污染的食品对疾病的传播作用明显。     

上海市由腹泻综合监测系统发现的1例O157∶H7感染性腹泻病例的确认及流行病学调查

目的分析上海市首例由腹泻综合监测系统报告的肠出血性大肠杆菌(E.coli)O157∶H7感染性腹泻病例的发现过程及流行病学特征,为防制O157∶H7感染提供依据。方法收集病例的流行病调查资料及临床病史,结合实验室检查结果和历史监测数据进行描述性分析。结果 2013—2015年上海市腹泻综合监测点累计采样8 441例,未检出肠出血性大肠杆菌。2016年6月首次由腹泻患者粪便标本中,检出肠出血性大肠杆菌O157∶H7产毒株,采集密切接触者共8份粪便标本和环节样本3份,均未检出O157∶H7。结论本起E.coli O157∶H7感染散发疫情由腹泻综合监测系统发现,应强化腹泻综合监测系统的作用,及时发现传染源,有效控制肠道传染病传播风险。     

出血性大肠杆菌O157：H7 DNA文库的构建

目的：为建立出血性大肠杆菌O157：H7 DNA文库,筛选致病岛LEE。方法：提取EHEC O157：H7 EDL933染色体,Xmal部分酶切并与pJB8X连接,包装,感染E.coli DH5a,鉴定库容,结果：库容约700克隆子,大于608个理论值,构建成功,结论：成功构建了出血性大肠杆菌O157：H7 DNA文库,为目的片段筛选打下了良好基础。     

Estimation of the under-reporting rate for the surveillance of Escherichia coli O157:H7 cases in Ontario, Canada

Two models estimating the proportion of Escherichia coli O157:H7 cases not reported in the Ontario notifiable diseases surveillance system are described. The first model is a linear series of adjustments in which the total number of reported cases is corrected by successive underreporting coefficients. The structure of the second model is based on a relative difference in the proportion of E. coli O157:H7 cases which are hospitalized between the surveillance database and the underlying population. Based on this analysis, the rate of under-reporting of symptomatic cases of E. coli O157:H7 infection in Ontario ranges from 78 to 88% corresponding to a ratio of 1 reported case for approximately 4-8 symptomatic cases missed by the surveillance system. This study highlights the need to increase awareness among public health workers of the potential biases that may exist in the interpretation of routine surveillance data.     

Surveillance of Escherichia coli O157 isolation and confirmation, United States, 1988

In 1989, to examine patterns of testing for Escherichia coli O157:H7 in state public health laboratories (SPHLs), CDC conducted a survey to determine the availability and type of Escherichia coli O157:H7 testing in SPHLs during 1988 and the number of isolates confirmed at SPHLs if such testing was available. The results were compared with information on isolates submitted for confirmatory testing at CDC in 1988. Thirty-nine (78%) of the 51 SPHLs were testing for E. coli O157:H7 in 1988; 26 confirmed at least one E. coli O157 isolate in that year. CDC confirmed isolates from three additional states. A total of 489 E. coli O157:H7 or E. coli O157:NM isolates were identified, with the largest numbers being reported from Washington (156), Oregon (64), Minnesota (63), and Massachusetts (36). These results show that E. coli O157 has been detected in most areas of the United States. Infections are apparently concentrated in northern states; however, improved surveillance data are needed to determine regional incidence and trends.     

Persistence of Escherichia coli O157:H7 in dairy cattle and the dairy farm environment.

The persistence of Escherichia coli O157:H7 in cattle and the farm environment was investigated on eight Ontario dairy farms positive for E. coli O157:H7 in a longitudinal study commenced one year previously. Faecal samples from cows, calves, humans, cats, rodents, wild birds, a composite fly sample and numerous composite and individual environmental samples were cultured and tested for verotoxin-producing E. coli (VTEC). VTEC isolates were serotyped and E. coli O157:H7 isolates were phage typed. E. coli O157:H7 phage type 34 was isolated from one calf on each of two farms. The same phage type had been isolated on one of these farms 12 months earlier. Most E. coli O157:H7-positive animals and farms became culture-negative within 2 and 3 months, respectively. E. coli O157:H7 was not isolated from any environmental samples, although evidence of VTEC was found in composite samples from calf feeders (19.1%), calf barn surfaces (18%), cow feeders (14.9%), flies (12.5%), cow barn surfaces (11.3%), and individual milk filters (12.5%). VTEC belonging to 21 non-O157 serotypes were isolated from 24 cows (8.2%), 21 calves (18.3%), 2 cow feeder samples (3.0%), and 1 calf feeder sample (4.8%). Shedding of E. coli O157:H7 by infected dairy cattle appears to be transient and persistence of E. coli O157:H7 was not demonstrated from the farm environment sites tested.     

The role of heightened surveillance in an outbreak of Escherichia coli O157.H7.

After instituting laboratory screening for Escherichia coli O157.H7, a Connecticut hospital isolated the organism from four persons in September 1993. As a result, an outbreak of E. coli O157.H7 associated with a country club was detected. The club had served hamburger from the same shipment at two picnics. Attendees of two picnics were interviewed, stool cultures were obtained from symptomatic persons, and the remaining hamburger was cultured. Twenty (22%) of 89 persons who ate hamburger became ill, compared with 1 of 60 who did not eat hamburger (relative risk = 13.5, 95% confidence interval 3.2-56.3). Among persons who ate hamburgers, illness was strongly associated with eating hamburger that was not thoroughly cooked (P < 0.001). All 20 samples from 5 remaining boxes of patties yielded E. coli O157.H7. Isolates from hamburger and case-patients were indistinguishable by pulsed-field gel electrophoresis. Heightened surveillance can rapidly identify outbreaks and may mitigate their impact. However, continued review of food safety issues is necessary if E. coli O157.H7 outbreaks are to be prevented.     

Expression and putative roles in attachment of outer membrane proteins of Escherichia coli O157 from planktonic and sessile culture

Many strains of Shiga toxigenic Escherichia coli (STEC), particularly the serotype O157:H7, are foodborne pathogens causing disease in many countries throughout the world. E. coli O157:H7 is able to attach and survive on various surfaces such as stainless steel (SS) found within the food processing environment. We examined the outer membrane protein (OMP) profiles of four E. coli O157 (three toxigenic O157:H7 and one nontoxigenic O157:HR) and one non-STEC strain (O1:H7), previously reported to have different abilities to attach to SS following growth in planktonic (nutrient broth) and sessile (nutrient agar) culture. The OMPs of the five E. coli strains grown in planktonic and sessile culture were extracted using N-lauroyl sarcosine and the OMP profiles were separated using two-dimensional (2D) gel electrophoresis. Qualitative and quantitative variations in the total number of OMPs expressed between planktonic and sessile cultures were found for all E. coli isolates tested. A number of differentially expressed protein spots were selected from 2D gels and were identified. FlgE was found to be expressed in planktonic culture but not sessile culture. MipA and OmpX had higher expression in sessile culture than planktonic culture, while expression of OmpA did not differ between E. coli strains or between the two modes of growth. Although differential expression of OMPs was found between isolates grown in planktonic and sessile culture, further investigations are required to determine a role of some of these identified proteins during growth of E. coli in planktonic and sessile culture and their influence during the attachment process.     

大肠杆菌O157多克隆抗体及食品中双抗ELISA测定方法的研究

本研究获得了抗肠出血性大肠杆菌O157:H7的多克隆抗体 ,建立了一种适宜食品样品检测的双抗ELISA检测方法。该方法对纯培养菌液检出限为 10 3 ～ 10 4 cfu ml;只对O157菌株有特异性反应 ,对非O157菌株无交叉反应 ;经过增菌 ,鸡肉与牛奶染菌样品中的大肠杆菌O157的检出限均为 0 1cfu g(cfu ml)。     

Detection of Escherichia coli O157:H7 and Listeria monocytogenes in beef products by real-time polymerase chain reaction

Rapid methods for the detection of Escherichia coli O157:H7 and Listeria monocytogenes in food products are important to the food industry and for public health. Conventional microbiological methods and newly developed molecular-based techniques such as polymerase chain reaction (PCR)-based methods are time consuming. In this study, a faster method based on utilization of a hybridization probe with real-time PCR, was developed and applied for detection of E. coli O157:H7 and L. monocytogenes from artificially contaminated raw ground beef and fully cooked beef hotdogs. Target genes for E. coli O157:H7 and L. monocytogenes were rfbE and hylA, respectively. An analysis of 169 bacterial strains showed that the chosen primers and probes were specific for detection of E. coli O157:H7 and L. monocytogenes by real-time PCR. The assay was positive for nine of 10. E. coli O157:H7 strains, and all L. monocytogenes (7/7) strains evaluated. Bacterial strains lacking these genes were not detected by these assays. Detection limits of real-time PCR assays ranged from 10(3) to 10(8) colony forming units (CFU)/ml for E. coli O157:H7 in modified tryptic soy broth and 10(4) to 10(8) CFU/mL for L. monocytogenes in Fraser Broth. Detection sensitivity ranged from 10(3) to 10(4) CFU/g of raw ground beef or hotdog without enrichment for E. coli and L. monocytogenes. Approximately 1.4-2.2 CFU/g of E. coli O157:H7 in raw ground beef were detected following an enrichment step of 4 h. Approximately 1.2-6.0 CFU/g of L. monocytogenes in beef hotdogs were detected following an enrichment step of 30 h. The real-time PCR assays for detection of E. coli O157:H7 and L. monocytogenes in raw ground beef and beef hotdogs were specific, sensitive and rapid.     

Antimicrobial susceptibility and mechanism of resistance to antibiotics for Escherichia coli O157 and verotoxin-producing E. coli isolated in northern Kyushu and Yamaguchi area

The purpose of this study was to investigate the biochemical characteristics and antimicrobial susceptibility of Escherichia (E.) coli O157 and verotoxin-producing E. coli isolates from the Northern Kyushu Island and Yamaguchi area of Japan. A total of 54 isolates- 50 E. coli O157, 3 verotoxin-producing E. coli O26 and 1 verotoxin-producing E. coli O111 - were used in this study. Regarding H antigen, H7 type in E. coli O157 accounted for 98% (49/50), and residual 1 strain of E. coli O157 was untypable H type. Two of 3 E. coli O26 isolates were H11 type, residual 1 strain of E. coli O26 was untypable H type, and E. coli O111 isolate was non-motile strain. All 54 isolates were susceptible to cephems, fosfomycin, kanamycin, amikacin and co-trimoxazole. Tetracycline-resistant isolates existed in 13 of all 54 isolates, 5 of those 13 isolates had tetA, and the other 7 isolates had tetB. Eight amoxicillin-resistant isolates had TEM-1 beta-lactamase. Four of the 5 isolates that had tetA also had TEM-1 beta-lactamase. Nalidixic acid and 6 fluoroquinolone used had no insensitive or resistant isolates. Kanamycin-resistant isolates, fosfomycin- and nalidixic acid-insensitive isolates have been reported, so we must notice the antibiogram of such strains. It is important that the surveillance of antimicrobial susceptibility of enterohemorragic E. coli should be continued after this.     

Meningococcal disease at the University of Southampton: outbreak investigation

Between November 1992 and February 1993, a large outbreak of Escherichia coli O157:H7 infections occurred in the western USA and was associated with eating ground beef patties at restaurants of one fast-food chain. Restaurants that were epidemiologically linked with cases served patties produced on two consecutive dates; cultures of recalled ground beef patties produced on those dates yielded E. coli O157:H7 strains indistinguishable from those isolated from patients, confirming the vehicle of illness. Seventy-six ground beef patty samples were cultured quantitatively for E. coli O157:H7. The median most probable number of organisms was 1.5 per gram (range, < 0.3-15) or 67.5 organisms per patty (range, < 13.5-675). Correlation of the presence of E. coli O157:H7 with other bacterial indicators yielded a significant association between coliform count and the presence of E. coli O157:H7 (P = 0.04). A meat traceback to investigate possible sources of contamination revealed cattle were probably initially colonized with E. coli O157:H7, and that their slaughter caused surface contamination of meat, which once combined with meat from other sources, resulted in a large number of contaminated ground beef patties. Microbiological testing of meat from lots consumed by persons who became ill was suggestive of an infectious dose for E. coli O157:H7 of fewer than 700 organisms. These findings present a strong argument for enforcing zero tolerance for this organism in processed food and for markedly decreasing contamination of raw ground beef. Process controls that incorporate microbiological testing of meat may assist these efforts.     

The prevalence of Escherichia coli O157.H7 in dairy and beef cattle in Washington State.

Escherichia coli O157.H7 was found in 10 of 3570 (0.28%) faecal samples from dairy cattle in 5 of 60 herds (8.3%). Several tentative associations with manure handling and feeding management practices on dairy farms were identified. Faecal/urine slurry samples, bulk milk samples, and milk filters from dairy herds were negative for E. coli O157.H7. E. coli O157.H7 was also isolated from 10 of 1412 (0.71%) faecal samples from pastured beef cattle in 4 of 25 (16%) herds. The prevalence of E. coli O157.H7 excretion in feedlot beef cattle was 2 of 600 (0.33%). The identification of cattle management practices associated with colonization of cattle by E. coli O157.H7 suggests the possibility that human E. coli O157.H7 exposure may be reduced by cattle management procedures.