Vero cytotoxin-producing Escherichia coli, particularly serogroup O 157, associated with human infections in the United Kingdom: 1989-91.

This survey reports the results of investigations performed by the Laboratory of Enteric Pathogens (LEP), to identify evidence of human infection with Vero cytotoxin-producing Escherichia coli (VTEC) in the UK during the period 1989-91. Bacterial isolates, faecal specimens and serum samples were received from patients suffering from diarrhoea, bloody diarrhoea and haemolytic uraemic syndrome. Using serotyping, Vero cytotoxin gene probing and an ELISA for serum antibodies to E. coli O 157, evidence of infection was detected in 232, 428 and 615 individuals in 1989, 1990 and 1991 respectively. Of these individuals, 15% were reported as having HUS. Vero cytotoxin-producing E. coli O 157 was the most frequently encountered serogroup, with isolations from a total of 1092 individuals over the 3-year period. The incidence of VTEC infection increased from 0.41/100,000 in 1989 to 1.07/100,000 in 1991. The area with the highest rate of infection in each year was Scotland, increasing from 1.37/100,000 in 1989 to 3.97/100,000 in 1991.     

An outbreak of Escherichia coli O157 gastroenteritis in a care home for the elderly

In the summer of 2001 an outbreak of Escherichia coli O157 gastroenteritis affected staff and residents of a care home for the elderly in the West Midlands, UK. E. coli O157 phage type 2 was isolated from faeces in eight patients and 12 staff members. Thirty-five staff and 40 residents met the case definition for clinical gastrointestinal infection. Serological testing identified a further 14 possible cases of infection amongst asymptomatic staff and residents. The outbreak was atypical, as the disease seemed to be milder than has been observed in past outbreaks in similar settings. The index case, a member of staff, developed bloody diarrhoea and haemolytic-uraemic syndrome (HUS), but only one resident developed bloody diarrhoea and required hospitalization. No deaths occurred, despite the high-risk nature of the affected population. The source of the outbreak could not be identified. The prolonged nature of the outbreak and observed lapses in infection control practices indicated that person-to-person spread was the likely route of transmission. This outbreak illustrates the importance of observing appropriate infection control measures in the institutions providing residential and nursing care to the elderly.     

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.     

Three years experience of adults admitted to hospital in north-east Scotland with E. coli O157

To describe the epidemiology, clinical features, treatment and outcomes of adults with E. coli O157 infection presenting to Aberdeen Royal Infirmary over a three year period. METHODS: A retrospective casenote review. RESULTS: Thirty-two confirmed cases of E. coli O157 infection were admitted between 1997 and 2000. The median age was 58 years (range 16-93). Ten patients (31%) were from the city of Aberdeen and 22 (69%) from surrounding rural areas. Twenty-seven patients (85%) presented between May and October. The source of infection was unknown or unconfirmed in all cases. Bloody diarrhoea was present in 30 (94%). Leucocytosis was present in 18 (63%) but only four patients (13%) had a fever. Six of the 32 patients (19%) developed Haemolytic-Uraemic Syndrome (HUS) of whom 2 died. Ten patients received antibiotics of whom two developed HUS. Twenty-seven of the 32 (85%) had made a full recovery by time of discharge, three (9%) had impaired renal function and two (6%) died in hospital. CONCLUSION: E. coli O157 infection tends to occur sporadically in rural areas in North East Scotland. It is not usually associated with fever. Infection occurs more commonly in the summer and autumn. HUS complicates infection in almost one fifth of patients.     

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.     

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.     

Pathogenic potential to humans of bovine Escherichia coli O26, Scotland

Escherichia coli O26 and O157 have similar overall prevalences in cattle in Scotland, but in humans, Shiga toxin-producing E. coli O26 infections are fewer and clinically less severe than E. coli O157 infections. To investigate this discrepancy, we genotyped E. coli O26 isolates from cattle and humans in Scotland and continental Europe. The genetic background of some strains from Scotland was closely related to that of strains causing severe infections in Europe. Nonmetric multidimensional scaling found an association between hemolytic uremic syndrome (HUS) and multilocus sequence type 21 strains and confirmed the role of stx(2) in severe human disease. Although the prevalences of E. coli O26 and O157 on cattle farms in Scotland are equivalent, prevalence of more virulent strains is low, reducing human infection risk. However, new data on E. coli O26-associated HUS in humans highlight the need for surveillance of non-O157 enterohemorrhagic E. coli and for understanding stx(2) phage acquisition.     

Investigation and management of sporadic gastrointestinal infections with potentially Vero cytotoxin producing Escherichia coli in Scotland

Recognition of the potential of Escherichia coli O157 and other Vero cytotoxin producing E. coli (VTEC) organisms to cause serious disease led to the recommendation that all diarrhoeal stool specimens be examined for E. coli O157. National guidelines exist for the testing and exclusion of cases and contacts of VTEC infection. A survey was conducted to discover the extent to which these recommendations are followed in Scotland by asking about current practices for public health management of identified cases and laboratory investigation of E. coli infection. About two thirds of Scottish health boards followed national guidelines for testing and exclusion of cases and contacts of VTEC O157 infection. Most laboratories tested all diarrhoeal stools for E. coli O157 but detection methods varied and a minority tested selected stools for non-O157 E. coli serogroups. Standardisation of policies for laboratory testing of VTEC infection would improve national surveillance. Adherence to evidence based guidelines would standardise public health management of VTEC infections in Scotland.     

Enteroaggregative E. coli O104 from an outbreak of HUS in Germany 2011, could it happen again?

Enterohaemorrhagic E. coli (EHEC) particularly O157:H7 (Sequence type 11 complex), is the best documented and most well-known of E. coli that cause diarrhoea. The importance of EHEC lies in the severity of disease. Outbreaks can infect thousands of people causing bloody diarrhoea and haemolytic uremic syndrome (HUS) that in turn can result in protracted illness or even death. The ability of EHEC to colonise the human gut is normally associated with the presence of genes from another group of diarrhoeagenic E. coli, the enteropathogenic E. coli (EPEC), via the locus of enterocyte effacement. However, the massive outbreak in Germany was caused by an EHEC which had acquired virulence genes from yet another group of diarrhoeagenic E. coli, the enteroaggregative E. coli (EAEC). In reality EAEC is probably the most common bacterial cause of diarrhoea but is not identified in most diagnostic laboratories. This outbreak emphasises the importance of being able to detect all diarrhoeagenic E. coli and not to focus on E. coli O157:H7 alone. Routine surveillance systems for EAEC, a once ignored global pathogen, would go a long way to reaching this goal. This review describes methods for identifying non-O157 EHEC and describes the key genetic features of EHEC and EAEC. Our aim is to provide information for laboratories and policy makers which enables them to make informed decisions about the best methods available for detecting newly emergent strains of diarrhoeagenic E. coli.     

Vero cytotoxin-producing Escherichia coli, particularly serogroup O157, associated with human infections in England and Wales: 1992-4.

Investigations were performed by the Laboratory of Enteric Pathogens on Vero cytotoxin-producing Escherichia coli (VTEC) in England and Wales from 1992-4. Bacterial isolates, faeces and sera obtained from patients with diarrhoea, bloody diarrhoea and haemolytic uraemic syndrome were examined. Using serotyping, Vero cytotoxin gene probing and serodiagnostic tests for E. coli O157, evidence of infection was detected in 543, 434 and 491 individuals in 1992, 1993 and 1994 respectively; VTEC of serogroup O157 were isolated from 470, 385 and 411 cases. The O157 VTEC strains belonged to at least 19 different phage types (PT) although 84% belonged to PT2, PT49, PT8, PT1 or PT4. Antibodies to E. coli O157 lipopolysaccharide were detected in 13% of the cases. The average annual rate of infection with O157 VTEC was 0.83/100000 and 12% of the 1458 individuals with evidence of infection with VTEC or E. coli O157 developed haemolytic uraemic syndrome. There were at least 18 general outbreaks and many family outbreaks.     

An outbreak of infection due to verocytotoxin-producing Escherichia coli O157 in four families: the influence of laboratory methods on the outcome of the investigation.

Three members of family A, who had diarrhoea on 20 October, lived on a small arable farm which had 10 cattle. Manure from the animals was used to fertilize the ground for growing potatoes which were then offered for retail sale, unwashed, directly from the farm. The mother from family B bought potatoes, which were covered with manure, from family A in early November and over the subsequent 10 days she became ill with diarrhoea and her daughter and son both became ill with bloody diarrhoea. The mother from family C visited family B while the daughter from the latter family was symptomatic; the mother developed diarrhoea several days later. The mother and two sons from family D visited family B while the son from the latter family was symptomatic; the first son developed bloody diarrhoea 6 days later which progressed to development of haemolytic-uraemic syndrome. Direct culture of faecal samples onto cefixime rhamnose sorbitol MacConkey agar failed to isolate E. coli O157 from any of the symptomatic patients, and direct culture onto cefixime tellurite sorbitol MacConkey agar isolated the organism from only one patient. In contrast, a combination of isolation of E. coli O157 by immunomagnetic separation and detection of E. coli O157-specific secretory IgA, suggested E. coli O157 infection in all eight symptomatic patients, but not in any of the family members who were not ill. Two children who excreted the organism for 60 and 89 days respectively were the only two patients who did not develop a secretory IgA response. E. coli O157 was not isolated from potatoes from the farm and faecal samples from the farm animals were not available for examination. The study illustrates the need to use the most sensitive methods available during the investigation and follow up of cases of E. coli O157 infection.     

A prospective study of exposure to verotoxin-producing Escherichia coli among Canadian children with haemolytic uraemic syndrome. The CPKDRC co-investigators.

Haemolytic uraemic syndrome (HUS) is a leading cause of acute renal failure in childhood. Although infection with Escherichia coli O 157. H7 has been associated with HUS in North America and Europe, only a limited number of studies have examined the role of other verotoxin-producing E. coli (VTEC) serotypes in this condition. To address this issue, we conducted a comprehensive, prospective microbiological study of patients treated for HUS at eight Canadian hospitals in the summer of 1990. Of the 34 consecutive patients with HUS enrolled over 4 months, E. coli O 157. H7 was isolated from the stools of 26, and other E. coli serotypes were isolated from four patients. In four subjects no pathogenic E. coli serotypes were identified on stool culture. Using oligonucleotide probes specific for VT-1 and VT-2, verotoxin genes were detected in the stool isolates of all patients with E. coli O 157. H7, and from two with other E. coli serotypes. Two other patients had at least a fourfold rise in anti-verotoxin antibodies. Strong evidence of exposure to a verotoxin was present in 30/34 (88%). Patients with E. coli O 157. H7 infection were more likely to develop an antibody response to VT-2 than to VT-1 (22/22 vs 12/22; P = 0.002). These results further strengthen the association of HUS with verotoxin-producing E. coli in North America, and confirm that E. coli serotypes other than O 157.H7 are isolated in a small proportion of summertime HUS episodes.     

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.     

Sequence heterogeneity of the eae gene and detection of verotoxin-producing Escherichia coli using serotype-specific primers.

The distribution of the Escherichia coli attaching and effacing (eae) gene in strains of verotoxin-producing E. coli (VTEC) isolated from cattle and humans was studied. The majority of strains isolated from humans with bloody diarrhoea or HUS and cattle with severe diarrhoea were eae positive (82 and 83% respectively). In contrast, 59% of VTEC isolated from asymptomatic cattle were eae negative and of the remaining 41% that were eae positive, the majority were serotype O157. H7. The nucleotide sequence of the 3'' end of the eae gene of enteropathogenic E. coli (EPEC) of serotype O55. H7 was found to be almost identical to that of serotype O157. H7. Specific primers are described which detect the eae sequences of VTEC serotypes O157. H7, O157. H-, and EPEC serotypes O55. H7 and O55. H-. The nucleotide sequence of the 3'' end of the eae gene of serotype O111. H8 differed significantly from that of O157. H7. Primers were developed to specifically identify the eae sequences of VTEC serotypes O111. H- and O111. H8. We conclude that whereas the majority of VTEC associated with disease in cattle and humans possess the eae gene, the gene itself may not be necessary to produce haemorrhagic colitis and HUS. Sequence heterogeneity in the 3'' end of eae alleles of VTEC permits specific identification of subsets of these organisms.     

Escherichia coli O157: comparing awareness of rural residents and visitors in livestock farming areas

This research compared public opinions about Escherichia coli O157 (an increasing environmental hazard associated with livestock) in two farming areas with contrasting incidence of E. coli O157 disease. A questionnaire was administered in rural Grampian (10·8 cases/100,000 population per year) and North Wales (2·5 cases/100,000 population per year). Awareness was highest among farmers in Grampian (91%) and lowest among visitors to both areas (28%). Respondents were more likely to indicate vomiting (76%) than bloody diarrhoea (48%) as a common symptom. Undercooked meat and contact with farm animal faeces were identified by 60% of all respondents as risk factors who described 'basic hygiene' for risk reduction indoors. Visitors view E. coli O157 as a food hazard, not an environmental hazard that produces vomiting not dysentery. Efforts to reduce human infections in livestock farming areas could be improved with proximate reminders for visitors of the environmental pathway of E. coli O157 infection.     

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.     

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.     

Antibodies among healthy population of developing countries against enterohaemorrhagic Escherichia coli O157:H7

In Thailand, no reports are available on Escherichia coli serotype O157:H7, a causative agent of severe bloody diarrhoea, sometimes associated with haemolytic-uraemic syndrome and thrombotic thrombocytopenic purpura. The reason for the non-identification of infection due to E. coli O157 in this country and in other developing countries has not been rigorously discussed. The aim of this study was to determine the humoral response against the infectious organism. The IgM and IgG antibody responses against E. coli O157 lipopolysaccharide were studied using indirect enzyme-linked immunosorbent assay. Three hundred and thirty-two serum samples obtained from healthy blood donors and patients with diseases unrelated to diarrhoea were investigated. With a cut-off value of mean +2 SDs for each age-group, the frequency of the IgM and IgG responses to O157 lipopolysaccharide was 11.74% (39 of 332 samples) and 22.59% (75 of 332 samples) respectively. Furthermore, agglutination test of 173 subjects revealed titres ranging from 10 to 40 in all the samples. The results suggest possible exposure of the Thai population to cross-reacting antigens from other intestinal organisms in addition to infection due to E. coli O157:H7.     

Verotoxin-producing Escherichia coli infections in Sheffield: cattle as a possible source

During 1986 and 1987, faecal samples from patients with haemorrhagic colitis (HC) or haemolytic-uraemic syndrome (HUS) were examined for evidence of infection by verotoxin-producing Escherichia coli (VTEC). During the 2-year period VTEC infections were found in 31 (78%) of 40 patients initially presenting with HC, and in 5 (63%) of 8 patients initially presenting with HUS. VTEC were found in only 2 (0.9%) of 229 age and sex matched control patients with acute non-bloody diarrhoea. All but one VTEC belonged to E. coli serogroup O 157. During 1987 this serogroup was isolated from 2 (1%) of 207 samples of faeces taken from cattle arriving at a Sheffield abattoir, indicating a possible source of these infections for man. We are unaware of previous reports of isolation of this organism from cattle in England.     

Virulence factors for hemolytic uremic syndrome, Denmark

We present an analysis of strain and patient factors associated with the development of bloody diarrhea and hemolytic uremic syndrome (HUS) among Shiga toxin-producing Escherichia coli (STEC) patients registered in Denmark in a 6-year period. Of 343 STEC patients, bloody diarrhea developed in 36.4% and HUS in 6.1%. In a multivariate logistic regression model, risk factors for bloody diarrhea were the eae and stx2 genes, O groups O157 and O103, and increasing age. Risk factors for HUS were presence of the stx2 (odds ratio [OR] 18.9) and eae (OR undefined) genes, being a child, and having bloody diarrhea. O group O157, although associated with HUS in a univariate analysis (OR 4.0), was not associated in the multivariate analysis (OR 1.1). This finding indicates that, rather than the O group, the combined presence of the eae and stx2 genes is an important predictor of HUS.