Attribution of human infections with Shiga toxin‐producing Escherichia coli (STEC) to livestock sources and identification of source‐specific risk factors,The Netherlands (2010–2014)

Shiga toxin‐producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern whose sources and transmission routes are difficult to trace. Using a combined source attribution and case–control analysis, we determined the relative contributions of four putative livestock sources (cattle, small ruminants, pigs, poultry) to human STEC infections and their associated dietary, animal contact, temporal and socio‐econo‐demographic risk factors in the Netherlands in 2010/2011–2014. Dutch source data were supplemented with those from other European countries with similar STEC epidemiology. Human STEC infections were attributed to sources using both the modified Dutch model (mDM) and the modified Hald model (mHM) supplied with the same O‐serotyping data. Cattle accounted for 48.6% (mDM) and 53.1% (mHM) of the 1,183 human cases attributed, followed by small ruminants (mDM: 23.5%; mHM: 25.4%), pigs (mDM: 12.5%; mHM: 5.7%) and poultry (mDM: 2.7%; mHM: 3.1%), whereas the sources of the remaining 12.8% of cases could not be attributed. Of the top five O‐serotypes infecting humans, O157, O26, O91 and O103 were mainly attributed to cattle (61%–75%) and O146 to small ruminants (71%–77%). Significant risk factors for human STEC infection as a whole were the consumption of beef, raw/undercooked meat or cured meat/cold cuts. For cattle‐attributed STEC infections, specific risk factors were consuming raw meat spreads and beef. Consuming raw/undercooked or minced meat were risk factors for STEC infections attributed to small ruminants. For STEC infections attributed to pigs, only consuming raw/undercooked meat was significant. Consuming minced meat, raw/undercooked meat or cured meat/cold cuts were associated with poultry‐attributed STEC infections. Consuming raw vegetables was protective for all STEC infections. We concluded that domestic ruminants account for approximately three‐quarters of reported human STEC infections, whereas pigs and poultry play a minor role and that risk factors for human STEC infection vary according to the attributed source.     

Multiple‐Aetiology Enteric Infections Involving Non‐O157 Shiga Toxin‐Producing Escherichia coli – FoodNet, 2001–2010

We describe multiple‐aetiology infections involving non‐O157 Shiga toxin‐producing Escherichia coli (STEC) identified through laboratory‐based surveillance in nine FoodNet sites from 2001 to 2010. A multiple‐aetiology infection (MEI) was defined as isolation of non‐O157 STEC and laboratory evidence of any of the other nine pathogens under surveillance or isolation of >1 non‐O157 STEC serogroup from the same person within a 7‐day period. We compared exposures of patients with MEI during 2001–2010 with those of patients with single‐aetiology non‐O157 STEC infections (SEI) during 2008–2009 and with those of the FoodNet population from a survey conducted during 2006–2007. In total, 1870 non‐O157 STEC infections were reported; 68 (3.6%) were MEI; 60 included pathogens other than non‐O157 STEC; and eight involved >1 serogroup of non‐O157 STEC. Of the 68 MEI, 21 (31%) were part of six outbreaks. STEC O111 was isolated in 44% of all MEI. Of patients with MEI, 50% had contact with farm animals compared with 29% (P < 0.01) of persons with SEI; this difference was driven by infections involving STEC O111. More patients with non‐outbreak‐associated MEI reported drinking well water (62%) than respondents in a population survey (19%) (P < 0.01). Drinking well water and having contact with animals may be important exposures for MEI, especially those involving STEC O111.     

Pathogenic Shiga toxin-producing Escherichia coli in the intestine of calves

The purpose of this study was to compare the pathological effects of Shiga toxin-producing Escherichia coli (STEC) that vary in their association with bovine and human disease. Shiga toxin-producing E. coli of serotypes associated with both dysentery in calves and hemolytic uremic syndrome (HUS) in humans (O5:H-, O26:H11, O111:H-, O113:H21) were compared with O157:H7 STEC, which are associated with HUS in humans but not with disease in calves. The STEC were administered orally to 80 day-old chicks and into ligated loops in the ileum and colon of four 2- to 6-day-old calves. Examination of the ceca of the chickens 10 d postchallenge showed no adherence or tissue abnormality for any isolate. The calves were euthanized 8 to 10 h postinoculation, and sections of the intestinal loops were examined by light microscopy, transmission and scanning electron microscopy, and immunohistochemistry. All strains showed consistent focal adherence associated with mild lesions in the colon. Attaching and effacing lesions were observed with the eae-positive strains. Ileal lesions were similar to the colonic ones but were sometimes severe, with marked polymorphonuclear leukocyte proliferation in the lamina propria. It is concluded that chickens were unsuitable for studying interaction of STEC with the intestine and that there was no difference in the interaction of the ligated calf intestine with STEC of serotypes associated with disease in calves compared with O157:H7 STEC.     

An investigation of shedding and super‐shedding of Shiga toxigenic Escherichia coli O157 and E. coli O26 in cattle presented for slaughter in the Republic of Ireland

Shiga toxigenic Escherichia coli (STEC) are an important group of pathogens and can be transmitted to humans from direct or indirect contact with cattle faeces. This study investigated the shedding of E. coli O157 and O26 in cattle at the time of slaughter and factors associated with super‐shedding (SS) animals. Rectoanal mucosal swab (RAMS) samples were collected from cattle (n = 1,317) at three large Irish commercial beef abattoirs over an 18 month period, and metadata were collected at the time of sampling regarding farm of origin, animal age, breed and gender. RAMS swabs were examined for the presence and numbers of E. coli O157 and O26 using a previously developed quantitative real‐time PCR protocol. Samples positive by PCR were culturally examined and isolates analysed for the presence of stx subtypes, eae and phylogroup. Any samples with counts >10⁴ CFU/swab of STEC O157 or O26 were deemed to be super‐shedders. Overall, 4.18% (55/1,317) of RAMS samples were positive for STEC O157, and 2.13% (28/1,317) were classified as STEC O157 SS. For STEC O26, 0.76% (10/1,317) of cattle were positive for STEC O26, and 0.23% (3/1,317) were classified as super‐shedders. Fewer STEC shedders and SS were noted among older animals (>37 months). There was a seasonal trend observed for STEC O157, with the highest prevalence of shedding and SS events in the autumn (August to October). The majority of E. coli O157 (50/55) isolates had stx2 and were eae positive, with no significant difference between SS and low shedders (LS). Interestingly, all STEC O26 (n = 10) were eae negative and had varied stx profiles. This study demonstrates that, while the overall shedding rates are relatively low in cattle at slaughter, among positive animals there is a high level of SS, which may pose a higher risk of cross‐contamination during slaughter.     

Stochastic Simulation Model Comparing Distributions of STEC O157 Faecal Shedding Prevalence Between Cattle Vaccinated With Type III Secreted Protein Vaccines and Non‐Vaccinated Cattle

Pens of cattle with high Escherichia coli O157:H7 (STEC O157) prevalence at harvest may present a greater risk to food safety than pens of lower prevalence. Vaccination of live cattle against STEC O157 has been proposed as an approach to reduce STEC O157 prevalence in live cattle. Our objective was to create a stochastic simulation model to evaluate the effectiveness of pre‐harvest interventions. We used the model to compare STEC O157 prevalence distributions for summer‐ and winter‐fed cattle to summer‐fed cattle immunized with a type III secreted protein (TTSP) vaccine. Model inputs were an estimate of vaccine efficacy, observed frequency distributions for number of animals within a pen, and pen‐level faecal shedding prevalence for summer and winter. Uncertainty about vaccine efficacy was simulated using a log‐normal distribution (mean = 58%, SE = 0.14). Model outputs were distributions of STEC O157 faecal pen prevalence of summer‐fed cattle unvaccinated and vaccinated, and winter‐fed cattle unvaccinated. The simulation was performed 5000 times. Summer faecal prevalence ranged from 0% to 80% (average = 30%). Thirty‐six per cent of summer‐fed pens had STEC O157 prevalence >40%. Winter faecal prevalence ranged from 0% to 60% (average = 10%). Seven per cent of winter‐fed pens had STEC O157 prevalence >40%. Faecal prevalence for summer‐fed pens vaccinated with a 58% efficacious vaccine product ranged from 0% to 52% (average = 13%). Less than one per cent of vaccinated pens had STEC O157 prevalence >40%. In this simulation, vaccination mitigated the risk of STEC O157 faecal shedding to levels comparable to winter, with the major effects being reduced average shedding prevalence, reduced variability in prevalence distribution, and a reduction in the occurrence of the highest prevalence pens. Food safety decision‐makers may find this modelling approach useful for evaluating the value of pre‐harvest interventions.     

Desperately seeking diarrhoea: outbreak of haemolytic uraemic syndrome caused by emerging sorbitol-fermenting shiga toxin-producing Escherichia coli O157:H-, Germany, 2009

Infection with sorbitol-fermenting Shiga toxin-producing Escherichia coli O157:H- (sf STEC O157:H-) is rare, but emerging in Europe. The pathogen is typically isolated from paediatric patients with life-threatening haemolytic uraemic syndrome (HUS). It is unclear whether this observation primarily reflects the pathogen's virulence or its complex laboratory diagnosis, not routinely conducted in diarrhoeal patients. In summer 2009, four boys living in the same suburb in Germany developed diarrhoea-associated HUS: three were infected by sf STEC O157:H- and one died. We conducted two analytical epidemiological studies, an extensive search for diarrhoeal cases in potentially exposed groups, and an environmental investigation. Outbreak cases were residents of the suburb diagnosed with HUS, sf STEC O157:H- infection, or both between 24 July 2009 and 25 August 2009. Overall, we ascertained eight cases with a median age of 4 years (range: from 8 months to 9 years). Stool screening of 220 persons led to the identification of only four additional cases: two asymptomatic carriers and two diarrhoeal cases. HUS was strongly associated with visiting a local playground in July, particularly on 16th July (odds ratio = 42.7, P = 0.002). No other commonality, including food, was identified, and all environmental samples (n = 24) were negative. In this localized non-foodborne outbreak, the place of likely infection was a local playground. Sf STEC O157:H- infection apparently limits itself rarely to diarrhoeal illness and progresses frequently to HUS. Therefore, detection of and response to this hypervirulent pathogen primarily relies on HUS surveillance.     

An outbreak of Shiga toxin‐producing Escherichia coli O157:H7 linked to a mud‐based obstacle course,England, August 2018

In August 2018, Public Health England (PHE) was made aware of five probable cases of Shiga toxin‐producing Escherichia coli (STEC) O157:H7 among individuals reporting participation in a mud‐based obstacle race. An additional four cases, identified via routine whole‐genome sequencing, were subsequently linked to the same event. Two of the nine cases were due to secondary household transmission. Despite an agreement between the event organizers and the local authority, to ensure that all livestock were removed from the site 28 days before the event, sheep were observed grazing on some of the routes taken by the runners 2 days prior to the race taking place. A retrospective review of incidents reported to PHE between 2015 and 2018 identified 41 cases of gastroenteritis associated with muddy assault course events. Of these, 25 cases were due to infection with STEC O157:H7, of which all but one were associated with outbreaks. Due to the environment in which such events take place, it is impossible to entirely remove the risk of exposure to potentially pathogenic zoonoses. However, race organizers should ensure that livestock are removed from the course 28 days before the event. They should also ensure that participants are made aware of the risk of contracting gastrointestinal disease from the environment, and to stress the importance of hand hygiene post‐event and the risk of secondary transmission, particularly to children who are at risk of developing haemolytic uraemic syndrome.     

A National Surveillance of Shiga Toxin‐Producing Escherichia coli in Food‐Producing Animals in Japan

To assess the public health risk, the prevalence and anti‐microbial resistance of Shiga toxin‐producing Escherichia coli (STEC) among food‐producing animals were studied throughout Japan. Faecal samples were collected from healthy animals of 272 cattle, 179 pigs, and 158 broilers on 596 farms in all 47 Japanese prefectures. STEC were isolated from 62 (23%) cattle and 32 (14%) pig samples but from no chicken samples. Of the bovine isolates, 19 belonged to serotypes frequently implicated in human disease (O157:H7/non‐motile (NM)/H not typeable, O26:NM/H11/H21/H not typeable, O113:H21, and O145:NM). The eae genes were observed in 37% of bovine isolates; among them one O145:NM and all four O157 isolates possessed eae‐γ1, and one O145:NM, one O103:H11, and all five O26 isolates possessed eae‐β1 gene. Among the swine isolates, stx2e were dominant, and serotypes frequently implicated in human diseases or eae‐positive isolates were not observed. Bovine isolates showed less anti‐microbial resistance, but six isolates of 26:NM/H11 and O145:NM were multi‐resistant and may need careful monitoring. Swine isolates showed various resistance patterns; chloramphenicol resistance patterns were more common than in bovine isolates. This first national study of STEC in the Japanese veterinary field should aid our understanding of Japan's STEC status.     

Development of a PCR‐Based Method for Specific Identification of Genotypic Markers of Shiga Toxin‐Producing Escherichia coli Strains

A simple, rapid and specific PCR‐based method for identification of shiga toxin‐producing Escherichia coli (STEC) was developed. The procedure involves amplification of the E. coli‐specific universal stress protein A (uspA) gene (uspa‐PCR), with the primer pair described by other authors, which allows differentiation of E. coli (STEC and non‐STEC) from other gram‐negative bacteria followed by identification of the main genetic virulence traits of the uspA‐positive isolates. For this purpose, two multiplex PCR assays, based on previously published primer sequences, were established. Assay 1 (mPCR‐1) uses three primer pairs and detects the genes encoding O157 (rfb), enterohemolysin (ehly) and shiga toxin (stx), generating amplification products of 420, 534 and 230 bp, respectively. Assay 2 (mPCR‐2) uses four primer pairs specific for rfb (E. coli O157), eaeA (intimin), stx1 and stx2 (shiga toxin 1 and 2, respectively), generating PCR amplicons of 420, 840, 348 and 584 bp, respectively. These two assays were validated by testing several E. coli reference strains and 202 previously characterized E. coli isolates originating from calves and from children, and 100% agreement with previous results was obtained. The method developed can be used for specific identification of STEC bacteria including those of the O157 serogroup.     

Best Practices for Planning Events Encouraging Human–Animal Interactions

Educational events encouraging human–animal interaction include the risk of zoonotic disease transmission. It is estimated that 14% of all disease in the USA caused by Campylobacter spp., Cryptosporidium spp., Shiga toxin‐producing Escherichia coli (STEC) O157, non‐O157 STECs, Listeria monocytogenes, non‐typhoidal Salmonella enterica and Yersinia enterocolitica were attributable to animal contact. This article reviews best practices for organizing events where human–animal interactions are encouraged, with the objective of lowering the risk of zoonotic disease transmission.     

Application of a real-time PCR-based system for monitoring of O26, O103, O111, O145 and O157 Shiga toxin-producing Escherichia coli in cattle at slaughter

Faecal samples were collected from 573 slaughtered cattle aged between three and 24 months in seven abattoirs. After enrichment (mTSB with novobiocin), samples were screened by real‐time PCR first for stx and if positive, tested for the top‐five Shiga toxin‐producing Escherichia coli (STEC) serogroups using PCR assays targeting genes specific for serogroups O26, O103, O111, O145 and O157. Of 563 samples with available results, 74.1% tested positive for stx genes. Amongst them, the serogroups O145, O103, O26, O157 and O111 were detected in 41.9%, 25.9%, 23.9%, 7.8% and 0.8%, respectively. From 95 O26, 166 O145 and 30 O157 PCR‐positive samples, 17 O26, 28 O145 and 12 O157 strains were isolated by colony hybridization after immunomagnetic separation. The 17 O26 strains were eae‐positive, but only nine strains harboured stx (eight possessing stx1 and one stx2). Of the 28 O145 strains, ten were eae‐positive including four harbouring stx1 or stx2, whereas 18 were negative for stx and eae. Five of the 12 O157 strains harboured stx2 and eae, did not ferment sorbitol, and were identified as STEC O157:H7/H^?. The other seven O157 strains were negative for stx and eae or positive only for eae. Shiga toxin genes and the top‐five STEC serogroups were frequently found in young Swiss cattle at slaughter, but success rates for strain isolation were low and only few strains showed a virulence pattern of human pathogenic STEC.     

Severe Outbreak of Sorbitol‐Fermenting Escherichia coli O157 via Unpasteurized Milk and Farm Visits,Finland 2012

Shiga toxin‐producing, sorbitol‐fermenting Escherichia coli O157 (SF O157) has emerged as a cause of severe human illness. Despite frequent human findings, its transmission routes and reservoirs remain largely unknown. Foodborne transmission and reservoir in cattle have been suspected, but with limited supporting evidence. This study describes the outbreak of SF O157 that occurred in Finland in 2012. The outbreak originated from a recreational farm selling unpasteurized milk, as revealed by epidemiologic and microbiological investigations, and involved six hospitalized children and two asymptomatic adults with culture‐confirmed infection. An identical strain of SF O157 was isolated from patients, cattle and the farm environment, and epidemiologic analysis suggested unpasteurized milk as the vehicle of transmission. This study reports the first milkborne outbreak of SF O157, provides supporting evidence of cattle as a reservoir and highlights the health risks related to the consumption of unpasteurized milk.     

Escherichia coli O157:H7 – Discerning Facts from Fiction: An Integrated Research and Extension Project for Multiple Audiences

The O157:H7 (EcO157) epidemiology of Shiga‐toxin‐producing Escherichia coli (STEC) in cattle is complex, and myths about pre‐harvest control are perpetuated. The objectives of this project were to identify perpetuated misinformation and inform four audiences about evidence‐based risks and pre‐harvest control of EcO157 by addressing: (i) EcO157 epidemiology and pre‐harvest control; (ii) how food safety policy is created; and (iii) how to present accurate information about EcO157. An environmental scan using a daily Internet search helped identify themes for education. A literature review of pre‐harvest control measures contributed to the development of educational materials (fact sheets, website, web presentations and conferences). Conference 1 was a webinar with 315 registrants, 10 countries including 41 US states and four Canadian provinces. Most participants felt confident in using their new knowledge, more than half felt confident enough to answer EcO157 questions from the public and many would recommend the recorded version of the webinar to colleagues. Conference 2 was live in the Washington, DC, area with most participants employed by the US government. All agreed that they better understood pre‐harvest control, how food safety policy was made, and were confident they could create an effective message about STEC pre‐harvest control. Videos were posted and received 348 Internet visitors within 2 months. Conference 3 was a webinar with a live audience and Twitter feeds, targeting people who give nutrition advice. Almost all ranked the programme good to excellent and relevant to their work. About 25% indicated that they would share: ‘grass‐fed beef is not safer than grain‐fed’, 25% would share information on effectiveness of cattle vaccines, and 14% would share information on message mapping. Across all conferences, major changes in knowledge included the following: there is no additional risk of EcO157 shedding from grain‐fed versus grass‐fed cattle, pre‐harvest vaccination is efficacious, and production systems (pasture versus confinement) do not affect EcO157 shedding rates.     

Escherichia coli O157:H7 and other Shiga toxin-producing E. coli in white veal calves

The aims of the study were to determine the prevalence of enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) and other Shiga toxin-producing E. coli (STEC) in feces of white veal calves in an operation in Ontario, to evaluate exposure of the calves to EHEC O157, and to investigate the milk replacer diet and antimicrobial resistance as factors that might influence the prevalence of EHEC O157. Feces from three cohorts of 20-21 calves were collected weekly for 20 weeks and processed for isolation of EHEC O157:H7 and detection of STEC by an ELISA. Exposure to EHEC O157 was also investigated by measuring IgG and IgM antibodies to the O157 lipopolysaccharide (O157 Ab) in sera by ELISA. The prevalences of EHEC O157 were 0.17% of 1151 fecal samples and 3.2% of 62 calves, and for STEC were 68% of 1005 fecal samples and 100% of 62 calves. Seroconversion to active IgG and IgM O157 Ab responses in some calves was not associated with isolation of EHEC O157. The milk replacer contained low levels of antibodies to EHEC antigens and without antimicrobial drugs, it did not inhibit the growth of EHEC O157 in vitro. Two E. coli O157:H7 that were isolated were totally drug sensitive whereas 60 commensal E. coli isolates that were examined were highly resistant. Antibodies in milk replacer that might be protective in vivo, and susceptibility to antimicrobial agents in the milk replacer may contribute to the low prevalence of EHEC O157 in white veal calves.     

Occurrence of non-sorbitol fermenting, verocytotoxin-lacking Escherichia coli O157 on cattle farms

Escherichia coli O157 is often associated with hemorrhagic colitis and the hemolytic uremic syndrome (HUS). The verocytotoxins are considered to be the major virulence determinants. However, vt-negative E. coli O157 were recently isolated from patients with HUS. Several transmission routes to humans are described, but cattle feces are the primary source from which both the food supply and the environment become contaminated with E. coli O157.In a prevalence study performed on dairy, beef, mixed dairy/beef and veal farms in the summer of 2007, vt-negative isolates were detected on 11.8% (8/68) of the positive farms. From these eight farms, a total of 43 sorbitol-negative E. coli O157:H7 were collected. On five farms, only strains negative for the vt genes were present whereas both vt-negative and vt-positive strains could be detected on three other farms. Further characterization revealed that all isolates carried the eaeA and hlyA genes. Pulsed-field gel electrophoresis (PFGE) of all isolates resulted in nine different PFGE types and within the vt-negative strains, four different genotypes were identified, indicating that certain genetic clones are widespread over the cattle population.     

Antibiotic‐resistant Shiga toxin‐producing Escherichia coli: An overview of prevalence and intervention strategies

Shiga toxin‐producing Escherichia coli (STEC) are foodborne pathogens that can cause severe diseases, including bloody diarrhoea and kidney failure, in humans, while remaining harmless to its primary reservoir hosts, cattle. Antibiotics such as azithromycin, fosfomycin and meropenem are being used and recommended in the treatment of early‐stage STEC (mainly E. coli O157:H7) infections, as these are reportedly effective in preventing Shiga toxin release and kidney failure while eliminating the pathogen. However, antibiotic resistance among STEC isolates could negatively impact these and other similar treatment options while contributing towards the spread of antibiotic resistance genes especially if encoded on mobile genetic elements like plasmids. Antibiotic resistance among STEC isolates recovered from animals and patients is being reported globally. A comprehensive understanding of the prevalence of antibiotic‐resistant STEC (AR‐STEC) and the mechanisms promoting this resistance among these bacteria could help direct therapies and develop strategies to effectively reduce/eliminate these pathogens. Here, we have reviewed literature from the past three decades to gain insights on this prevalence and its impact on human infections. In addition, we have reviewed various strategies proposed by researchers to control STEC that in turn would be applicable to AR‐STEC as well.     

Detection of Shiga Toxin‐Producing Escherichia coli and Enteropathogenic Escherichia coli in Faecal Samples of Healthy Mithun (Bos frontalis) by Multiplex Polymerase Chain Reaction

Faecal samples obtained from 190 healthy mithuns were examined for the presence of Escherichia coli. Total one‐hundred and five E. coli isolates were obtained from these samples, which belonged to 55 different serogroups. These isolates were subjected to multiplex polymerase chain reaction (m‐PCR) for detection of stx1, stx2, eaeA and hlyA genes. Twenty‐three (21.90%) E. coli isolates belonging to 14 serogroups revealed the presence of at least one virulence gene when examined by m‐PCR. Nineteen percent and 2.85% of the mithuns were found to carry Shiga toxin‐producing E. coli (STEC) and enteropathogenic E. coli, respectively. stx1 and stx2 genes were found to be prevalent in 7 (6.67%) and 18 (17.14%) of the isolates respectively, whereas eaeA and hlyA genes were found to be carried by three (2.85% each) isolates. Interestingly, none of the STEC isolates belonged to serogroup O157.     

In vitro reactivity and growth inhibition of EPEC serotype O111 and STEC serotypes O111 and O157 by homologous and heterologous chicken egg yolk antibody

IgY is a chicken egg yolk antibody which has been used for treatment and prophylaxis of gastrointestinal infections. Our aim was to verify if IgY obtained from chickens immunized with EPEC O111, STEC O111 and STEC O157 is able to show in vitro reactivity and biological activity towards the three bacteria. IgY was obtained from eggs laid before and after immunization with each bacterium. The preparations of IgY anti-EPEC O111 and anti-STEC O111 shared high reactivity detected by ELISA and growth inhibition ability towards both bacteria EPEC O111 and STEC O111. Nevertheless, the preparation of IgY anti-STEC O157 showed high reactivity and growth inhibitory effect only towards the homologous strain. Our results showing in vitro biological activity of IgY reinforce its use as an alternative for the treatment or prophylaxis of E. coli infections and encourage the development of in vivo studies for a possible future human therapeutic use.     

Shiga toxin-producing Escherichia coli O157:H7 from extensive cattle of the fighting bulls breed

Shiga toxin-producing Escherichia coli (STEC) O157:H7 represents a major public health concern worldwide, with cattle recognized as their main natural reservoir. The aim of this work was to determine the prevalence and the pheno-genotypic characteristics of STEC O157:H7 in a herd with 268 cattle of the fighting bulls breed (De Lidia breed) managed under extensive conditions in the South-West of Spain. Rectal-anal swabs of all animals were collected and examined for STEC O157:H7 by performing an immunomagnetic concentration and separation procedure combined with PCR, and the resulting isolates were characterized by both phenotypic and genotypic methods. Overall, STEC O157:H7 was isolated from seven animals (2.6%) in the herd. The PCR procedure indicated that all seven isolates displayed stx₂, eae-γ1, ehxA, O157 rfbE, and fliCh7 genes. They belonged to phage types 4 (one isolate) and 42 (two isolates), and four isolates reacted with typing phages but did not conform to a recognized pattern. Among the seven isolates there were five indistinguishable PFGE patterns and other two which differed only in ?2 restriction fragments, supporting the existence of horizontal transmission among animals in the herd. The present study demonstrates that cattle managed under extensive conditions in Spain can excrete STEC O157:H7 with their faeces. To our knowledge this is the first isolation of this pathogen from De Lidia cattle.     

A Multi‐Level Approach for Investigating Socio‐Economic and Agricultural Risk Factors Associated with Rates of Reported Cases of Escherichia coli O157 in Humans in Alberta,Canada

Using negative binomial and multi‐level Poisson models, the authors determined the statistical significance of agricultural and socio‐economic risk factors for rates of reported disease associated with Escherichia coli O157 in census subdivisions (CSDs) in Alberta, Canada, 2000–2002. Variables relating to population stability, aboriginal composition of the CSDs, and the economic relationship between CSDs and urban centres were significant risk factors. The percentage of individuals living in low‐income households was not a statistically significant risk factor for rates of disease. The statistical significance of cattle density, recorded at a higher geographical level, depended on the method used to correct for overdispersion, the number of levels included in the multi‐level models, and the choice of using all reported cases or only sporadic cases. Our results highlight the importance of local socio‐economic risk factors in determining rates of disease associated with E. coli O157, but their relationship with individual risk factors requires further evaluation.