肠出血性大肠杆菌O104:H4病原学及其检测方法研究进展

2011年5月以来,德国暴发了由肠出血性大肠杆菌O104:H4感染引起的疫情,世界多个国家相继报告有此类病例发生,这是首次报告由肠出血性大肠杆菌O104:H4感染引起疾病的暴发流行。截至2011年6月24日,已造成3920例感染和48例死亡[1]。该病患者以血水样腹泻、呕吐起病,部分病例并发溶血性尿毒综合征,导致多器官受损,甚至死亡。疫情发生后,世界各国相关学者立即开展其病原学特性研究,同时迅速研制出实验室检测方法和试剂,为该病的及时诊断、治疗和疫情控制发挥了很大作用。本文介绍了肠出血性大肠杆菌O104:H4病原学及其检测方法的研究进展。     

Outbreak of Shiga toxin-producing Escherichia coli and haemolytic uraemic syndrome

Enterohaemorrhagic Escherichia coli (EHEC) is a group of pathogenic Shiga toxin-producing E. coli that can cause haemorrhagic colitis and haemolytic uraemic syndrome (HUS). The disease usually occurs sporadically, but sometimes also occurs in large outbreaks such as that which recently occurred in northern Germany. EHEC infection is a zoonosis and its reservoir is in ruminant farm animals (cattle, sheep and goats). EHEC infection should be considered in patients with bloody diarrhoea, but in the course of many severe EHEC infections a picture resembling HUS may also occur. Antibiotic treatment is contraindicated because it does not reduce the duration of the disease and may have negative complications. Patients with EHEC infection may spread the bacteria and their care includes contact isolation measures with their own toilet facilities. The E. coli type O104:H4 that occurred in Germany has a combination of specific virulence characteristics. This outbreak affected many people who developed HUS and neurological symptoms following bloody diarrhoea.     

Verotoxinogenic Citrobacter freundii associated with severe gastroenteritis and cases of haemolytic uraemic syndrome in a nursery school: green butter as the infection source.

A summer outbreak of severe gastroenteritis followed by haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura in a nursery school and kindergarten is described. Sandwiches prepared with green butter made with contaminated parsley were the likely vehicle of infection. The parsley originated from an organic garden in which manure of pig origin was used instead of artificial fertilizers. Clonally identical verotoxinogenic Citrobacter freundii were found as causative agents of HUS and gastroenteritis and were also detected on the parsley.     

德国肠出血性大肠杆菌O104:H4暴发疫情带来的思考

2011年4月以来,德国多个地方肠出血性大肠杆菌(EHEC)O104:H4感染和溶血性尿毒综合征(HUS)疫情暴发。本文概述本次疫情的概况以及德国政府采取的应对措施,并从机构协作、信息公开、流行病学发挥的作用、症状监测重要性四个方面讨论对我国口岸卫生检疫工作的启示。     

Epidemiological analysis of a cluster within the outbreak of Shiga toxin-producing Escherichia coli serotype O104:H4 in Northern Germany, 2011

In May 2011 one of the worldwide largest outbreaks of haemolytic uraemic syndrome (HUS) and bloody diarrhoea caused by Shiga toxin-producing Escherichia coli (STEC) serotype O104:H4 occurred in Germany. One of the most affected federal states was Lower Saxony. We present the investigation of a cluster of STEC and HUS cases within this outbreak by means of a retrospective cohort study. After a 70th birthday celebration which took place on 7th of May 2011 among 72 attendants seven confirmed cases and four probable cases were identified, two of them developed HUS. Median incubation period was 10 days. Only 35 persons (48.6%) definitely answered the question whether they had eaten the sprouts that were used for garnishing the salad. Univariable analysis revealed different food items, depending on the case definition, with Odds Ratio (OR) > 1 indicating an association with STEC infection, but multivariable logistic regression showed no increased risk for STEC infection for any food item and any case definition. Sprouts as the source for the infection had to be assumed based on the results of a tracing back of the delivery ways from the catering company to the sprouts producer who was finally identified as the source of the entire German outbreak. In this large outbreak several case–control studies failed to identify the source of infection.     

Investigation of human infections with verocytotoxin-producing strains of Escherichia coli (VTEC) belonging to serogroup O118 with evidence for zoonotic transmission

Twenty verocytotoxigenic Escherichia coli (VTEC) O118 strains isolated between 1996 and 1998 from human patients in Germany were analysed for their serotypes, their virulence markers and their epidemiological relatedness. Three strains were typed as O118:H12, these carried only the VT2d-Ount variant gene and were not associated with diarrhoea or haemolytic uraemic syndrome (HUS). Seventeen strains were serotyped as O118:H16 or O118:non-motile (NM). These carried all the genes for VTI, eae and EHEC-haemolysin. The O118:H16/NM strains were from diarrhoea (13 cases) and HUS (2 cases). Sixteen of the patients were young infants and most infections were associated with a rural environment. Evidence for zoonotic transmission from cattle to humans was found in two cases. The epidemiological relationship between the human and bovine O118:H16/NM isolates was indicated by homogeneous plasmid patterns and by very similar XbaI restriction patterns obtained by pulsed-field gel electrophoresis. VTEC O118:H16/NM are emerging pathogens in Germany and should be classified as new enterohaemorrhagic E. coli (EHEC) types.     

Community-wide outbreak of Escherichia coli O157:H7 associated with consumption of frozen beef burgers

On 24-25 October 2005 a cluster of five haemolytic uraemic syndrome (HUS) cases was reported in southwest France. An investigation was undertaken to identify the outbreak source and implement control measures. Cases were defined as individuals with HUS or diarrhoea with isolation of Escherichia coli O157:H7 in stools or a positive antibody response to E. coli O157 lipopolysaccharide, resident in southwest France with symptom onset after 19 September 2005. Sixty-nine identified patients had symptom onset between 5 October and 3 November 2005, including 17 cases of HUS. One brand of frozen beef burgers produced on 22 August 2005 was consumed by all patients in the week before symptom onset. E. coli O157:H7 strains from patients, patients' burgers and the manufacturing plant were genetically related. This is the largest community-wide outbreak of E. coli O157:H7 in France to date and the first associated with consumption of contaminated frozen beef burgers.     

Monitoring patients in the community with suspected Escherichia coli O157 infection during a large outbreak in Scotland in 1996.

During outbreaks of Escherichia coli O157 a minority of patients with suspected infection develop haemolytic uraemic syndrome (HUS). The ability to identify this subgroup at an early stage is beneficial as mortality from HUS is high and may be influenced by intervention. During the 1996 Central Scotland E. coli O157 outbreak, of 886 patients from the community with suspected infection monitored at an outbreak clinic, nine developed HUS. We assessed factors associated with the development of HUS in this group. Children and the elderly were at increased risk of HUS. However, high white cell count was as least as good a predictor of HUS as age. High white cell counts predicted development of HUS with a sensitivity of 89%, specificity of 87%, positive predictive value of 7% and a negative predictive value of over 99%. We have used the results from this study along with other currently available evidence to propose a monitoring protocol for patients from the community with suspected E. coli O157 infection.     

Escherichia coli O104:H4 outbreak from sprouted seeds

From May to July 2011, one of the largest reported outbreaks of haemolytic uraemic syndrome (HUS) and bloody diarrhoea caused by the Shiga toxin-producing Escherichia coli (STEC) O104:H4 occurred in Germany and France. The hypothetical origin of the outbreak strain was a combined enteroaggregative E. coli and an enterohaemorrhagic E. coli with the ability to resist multi-antibiotics and produce Shiga-toxin 2. The combination of aggregative ability, antibiotic resistance and the production of Shiga-toxin 2 significantly affected the severity of the symptoms presented. Since humans may be the primary reservoir, it is likely that contamination could have occurred through contact with infected individuals. Farm food safety management, and hand hygiene training programmes are crucial to primary production to prevent or reduce risks of contamination.     

Epidemiology of infection due to Escherichia coli O157: a 3-year prospective study.

A 3-year study of Escherichia coli infections in Grampian Region was conducted to ascertain the incidence, document clinical sequelae and identify at-risk groups. Approximately 30,000 stools from patients with acute diarrhoea were screened for E. coli O157, and an epidemiological questionnaire filled in for each patient whose stool was positive. Eighty-three patients were studied. The annual incidence was 6 per 100, 000. Proportionately more infections occurred in people involved in agriculture. Evidence was seen of case-to-case transmission, and contamination of a water supply. Eight cases developed haemolytic uraemic syndrome (HUS). There were 2 deaths due to HUS and 2 due to haemorrhagic colitis (HC). Symptomatic E. coli infection is relatively common in the Grampian Region, more common in the agricultural community, and is the main cause of HUS in this Region.     

Predictors for the development of haemolytic uraemic syndrome with Escherichia coli O157:H7 infections: with focus on the day of illness

A large outbreak of Escherichia coli O157 infections via school lunches occurred at primary schools in 1996 in Sakai City, Japan. As many as 10,000 patients suffered from diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome (HUS). Using data on 288 inpatient school children affected by this outbreak, of whom 36 presented complete HUS and the remaining 252 tested positive for E. coli O157 culture, we attempted to identify predictors for the progression to HUS. Within the first 5 days of illness, clinical features associated with inpatients who developed HUS compared with those without HUS included a C reactive protein (CRP) level higher than 1.2 mg/dl (OR 44.26; 95% CI 5.83-336.23), a white blood cell (WBC) count greater than 11.0 x 10(9)/l (OR 5.03; 95% CI 2.13-11.87) and a temperature higher than 38.0 degrees C (OR 5.00; 95% CI 2.25-11.08). It can be concluded that these three factors are predictive factors for the development of HUS in patients with E. coli O157 infection, and patients who have two or all of these factors should be observed closely.     

Phage-typing of Vero-cytotoxin (VT) producing Escherichia coli O157 isolated in the United Kingdom

Vero-cytotoxin (VT) producing Escherichia coli serogroup O157 have been isolated from patients with diarrhoea, haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS). A phage-typing scheme developed in Canada has been used to type 155 VT+ E. coli O157 serogroup isolated from sporadic infections in the UK since 1983, and 48 strains from HC or HUS outbreaks. Twelve phage types were identified of which three, types 49, 51 and 52, have not been found in North America. All strains carried a 60 x 10(6) plasmid and most VT1+VT2+ strains also had a 5 x 10(6) plasmid coding for colicin D production. The majority of strains producing both VT1 and VT2 belonged to phage type 1, or the related types 4, 8 and 14. Most strains producing only VT2 belonged to types 2 or 49. Four outbreaks were included in the survey. Three had strains of a single phage type while strains from the fourth outbreak were more variable. The distribution of phage types throughout the UK showed no marked geographical variations.     

Haemolytic anaemia after childhood Escherichia coli O 157 .H7 infection: are females at increased risk?

We conducted a 4-year retrospective cohort study to better define the risk of haemolytic anaemia and haemolytic uraemic syndrome (HUS) in children following sporadic gastrointestinal infection with the O 157.H7 serotype of Escherichia coli. Of the 72 children infected with this organism, 9 (12.5%) developed haemolytic anaemia, 6 of whom had HUS. No child in a cohort of 72 age-matched controls with Campylobacter jejuni gastroenteritis developed haemolytic anaemia (P = 0.003). Females had a significantly greater risk of developing haemolytic anaemia after E. coli O 157. H7 infection than did males (8/29 females v. 1/43 males; P = 0.003). In a logistic regression model, female gender emerged as the only statistically significant risk factor for haemolytic anaemia (odds ratio 3.85; 95% confidence interval 1.24-12). These results are consistent with recent reports of a moderate increase in the risk of HUS for females.     

Outbreak of Vero cytotoxin-producing Escherichia coli O157 in a child day care facility

In December 1998, an outbreak of Vero cytotoxin-producing Escherichia coli (VTEC) O157 in a crèche affected ten out of 45 children and one out of five staff members. Eight cases were symptomatic and three were asymptomatic. There were two asymptomatic adult family contacts of child cases. All specimens were identified as VTEC O157:H7, phage type 32. None of the cases were seriously ill and none developed haemolytic uraemic syndrome (HUS). One child continued to excrete the organism for 14 weeks. The origin of the outbreak was not found but epidemiological investigation was suggestive of person-to-person spread. All children and staff were screened and excluded from the crèche until microbiological clearance was obtained. An inspection of the crèche revealed overcrowding and inadequacies in cleaning and in the food preparation facilities. These problems were remedied before children were re-admitted to the crèche. This outbreak demonstrates the ease with which VTEC O157 can be transmitted between small children. Two specific features of this outbreak were notable: (1) the mild self-limiting nature of the illness and (2) the prolonged shedding of the bacterium by one child.     

Gastrointestinal complications of the haemolytic uraemic syndrome.

The haemolytic uraemic syndrome (HUS) is a well recognized cause of acute renal failure in children. Gastrointestinal involvement is common, and may result in rectal bleeding which can be an important presenting symptom. Previous publications have stressed the importance of correct diagnosis to avoid unnecessary surgery. Occasionally serious gastrointestinal complications do occur. We present five children with life-threatening gastrointestinal complications of the HUS and discuss the indications for laparotomy.     

Prevention and control of enterohaemorrhagic Escherichia coli (EHEC) infections: memorandum from a WHO meeting. WHO Consultation on Prevention and Control of Enterohaemorrhagic Escherichia coli (EHEC) Infections.

Escherichia coli is a commonly occurring inhabitant of the intestine of humans and other animals, but there are several pathogenic types of E. coli which cause a variety of human diseases. One of these pathogenic types, E. coli O157:H7, belongs to the group of enterohaemorrhagic E. coli (EHEC) which produce potent toxins and cause a particularly severe form of disease, haemorrhagic colitis (HC). About 10% of patients with HC can go on to develop haemolytic uraemic syndrome (HUS), a life-threatening complication of E. coli O157:H7 infection that is characterized by acute renal failure, haemolytic anaemia, and thrombocytopenia. These sequelae are particularly serious in young children and older people. On average, 2-7% of patients with HUS die, but in some outbreaks among the elderly the mortality rate has been as high as 50%. This Memorandum reviews the growing importance of E. coli O157:H7 as a foodborne pathogen and reports on the issues of surveillance, outbreak investigation, and control strategies with respect to EHEC infections that were discussed at the WHO Consultation on Prevention and Control of EHEC Infections, held in Geneva on 28 April to 1 May 1997. Recommended measures for prevention and control include the following: use of potable water in food production; presentation of clean animals at slaughter; improved hygiene throughout the slaughter process; appropriate use of food processing measures; thorough cooking of foods; and the education of food handlers, abattoir workers, and farm workers on the principles and application of food hygiene.     

Clinical surveillance of thrombotic microangiopathies in Scotland, 2003-2005

The prevalence, incidence and outcomes of haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are not well established in adults or children from prospective studies. We sought to identify both outcomes and current management strategies using prospective, national surveillance of HUS and TTP, from 2003 to 2005 inclusive. We also investigated the links between these disorders and factors implicated in the aetiology of HUS and TTP including infections, chemotherapy, and immunosuppression. Most cases of HUS were caused by verocytotoxin-producing Escherichia coli (VTEC), of which serotype O157 predominated, although other serotypes were identified. The list of predisposing factors for TTP was more varied although use of immunosuppressive agents and severe sepsis, were the most frequent precipitants. The study demonstrates that while differentiating between HUS and TTP is sometimes difficult, in most cases the two syndromes have quite different predisposing factors and clinical parameters, enabling clinical and epidemiological profiling for these disorders.     

An outbreak of E. coli O157 associated with a swimming pool: an unusual vehicle of transmission

Escherichia coli O157 causes a range of illnesses from mild diarrhoea to haemolytic uraemic syndrome (HUS) which carries a mortality rate of 3.7%. Infection is more common in the under-5s. Between 1995 and 2000, 106 outbreaks of E. coli O157 were reported in England and Wales. Recreational water is well documented as a transmission route for infectious diseases worldwide. In the United Kingdom there have been very few reported outbreaks associated with swimming pools due to the relative susceptibility of E. coli O157 to adequate levels of free chlorine. This report describes the investigation of an outbreak associated with a local leisure centre pool and makes recommendations about the safe management of such facilities.     

E. coli O157 phage type 21/28 outbreak in North Cumbria associated with pasteurized milk

In March 1999, a large community outbreak of Escherichia coli O157 infection occurred in North Cumbria. A total of 114 individuals were reported to the Outbreak Control Team (OCT); 88 had laboratory confirmed E. coli O157. Twenty-eight (32%) of the confirmed cases were admitted to hospital, including three children (3.4%) with haemolytic uraemic syndrome. There were no deaths. A case-control study found that illness was strongly associated with drinking pasteurized milk from a local farm (P = <0.0001) on single variable analysis. Microbiological investigations at the farm revealed E. coli O157 phage type (PT) 21/28 VT 2 which was indistinguishable from the human isolates by pulsed field gel electrophoresis. At the time of occurrence this was the largest E. coli O157 outbreak in England and Wales and the first E. coli O157 PT 21/28 VT 2 outbreak associated with pasteurized milk. This outbreak highlights lessons to be learnt regarding on-farm pasteurization.