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Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen associated with both outbreaks and sporadic cases of human disease, ranging from uncomplicated diarrhoea to haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS). STEC affects children, elderly and immuno-compromised patients. STEC is capable of producing Shiga toxin type 1 (Stx1), type 2 (Stx2) or both, encoded by stx1 and stx2 genes, respectively. These strains are likely to produce putative accessory virulence factors such as intimin (encoded by eae), an enterohaemolysin (EhxA) and an autoagglutinating protein commonly associated with eae-negative strains (Saa), both encoded by an enterohaemorrhagic plasmid. Several studies have confirmed that cattle are the principal reservoir of STEC (O157 and non-O157:H7 serotypes) and many of these serotypes have been involved in HUS and HC outbreaks in other countries. Transmission of STEC to humans occurs through the consumption of undercooked meat, vegetables and water contaminated by faeces of carriers and by person-to-person contact. Diagnostic methods have evolved to avoid selective diagnostics, currently using molecular techniques for typing and subtyping of strains. Control is still a challenge, although there are animal vaccines directed against the serotype O157:H7.
Enterohemorrhagic Escherichia coli (EHEC) belong to a group of emerging foodborne pathogens that are a significant public health threat throughout the world. Much is unknown about these organisms: their prevalence, their burden on public health and how they cause disease. The acquisition of virulence factors is responsible for transforming commensal E. coli into pathogens, as virulence factors allow for intimate adherence to and subsequent colonization of the gastrointestinal tract, evasion of the immune system and/or the ability to induce disease. Identifying virulence factors to serve as definitive markers of pathogenicity across EHEC seropathotypes, for molecular detection assays, is a focus of current research.
Shiga toxin-producing Escherichia coli (STEC) infections are a substantial health issue worldwide. Circa 2010, foodborne STEC caused > 1 million human illnesses, 128 deaths, and ~ 13,000 Disability Adjusted Life Years (DALYs). Targeting interventions appropriately relies on identifying those strains of greatest risk to human health and determining the types of foods that cause STEC infections. There are hundreds of STEC serotypes; however, based on the evidence gathered during the review, the Expert Group concluded that the serotype of the STEC strain should not be considered a virulence criterion. All STEC strains with the same serotype should not be assumed to carry the same virulence genes and to pose the same risk, as many STEC virulence genes are mobile and can be lost or transferred to other bacteria. this report proposes a set of criteria for categorizing the potential risk of severity of illness associated with a STEC in food is recommended based on evidence of virulence gene profiles and associations with clinical severity. The criteria could be applied by risk managers in a risk-based management approach to control STEC in food. While ruminants and, other land animals are considered the main reservoirs for STEC, various largescale outbreaks have been linked to other foods. Thus, the report also addresses source attribution of foodborne STEC infections globally in order to inform the development of international standards by the Codex Alimentarius on the control of STEC, and in particular identify the foods which should be the focus of those standards. Finally it provides a review of monitoring programmes and methodology for STEC which can serve as a reference for countries planning to develop such programmes.
Escherichia coli O157:H7 and over 380 non-O157 serotypes of Shiga toxin producing E. coli (STEC) are human food-borne pathogens that inhabit the hindgut of ruminants and are shed in the feces, which subsequently contaminate food products. Recent epidemiological data have shown that six non-O157 STEC (O26, O103, O111, O121, O45 and O145) account for majority of human STEC infections. Fecal shedding of STEC is influenced by a number of factors, including diets, supplements, and feed additives, because of their potential to alter hindgut ecosystem. Not much is known about the fecal shedding of non-O157 STEC in cattle because of lack of standardized detection methods. Fecal shedding of E. coli O157:H7 was studied to determine the effects of supplemental urea, monensin, an ionophore, and ractopamine, a beta-agonist. Cattle fed monensin at 44 mg/kg of feed had lower (P = 0.05) fecal O157:H7 prevalence than cattle fed 33 mg/kg. Supplemental urea (0.35 or 0.70% of the diet) and inclusion of ractopamine at 200 mg/animal/day had no effect on fecal shedding of E. coli O157:H7. In an experimental inoculation study, inclusion of corn starch to a distiller's grains (DG)-supplemented diet had no effect on fecal shedding of E. coli O157 suggesting that either the decreased starch content in the DG-supplemented diet is not a factor in the increased shedding of E. coli O157:H7 or inclusion of pure starch in the diet may not have achieved our intended goal to have starch flow into the hindgut similar to that of corn grain. A multiplex PCR to detect O26, O45, O103, O111, O121, O145, and O157 was designed and applicability to detect the seven serogroups in cattle feces was evaluated. A multiplex PCR, designed to detect E. coli O104, feces showed presence of O104 in cattle feces (20.6%), but the isolated strains did not carry genes characteristic of the virulent strain responsible for the 2011 food-borne outbreak in Germany. Two preharvest interventions, a siderophore receptor and porin proteins-based vaccine and a Lactobacillus acidophilus-based direct-fed microbial, intended to control E. coli O157, had no effect on fecal shedding of O26 assessed by culture-based or PCR-based method.
Although Shiga toxin-producing Escherichia coli (STEC) have been isolated from a variety of food production animals, they are most commonly associated with ruminants from which we derive meat and milk. Because of the widespread and diverse nature of ruminant-derived food production, coupled with the near ubiquity of STEC worldwide, there is no single definitive solution for controlling STEC that will work alone or in all situations. Instead, the introduction of multiple interventions applied in sequence, as a “multiple-hurdle scheme” at several points throughout the food chain (including processing, transport and handling) will be most effective. This report summarises the review and evaluation of interventions applied for the control of STEC in cattle, raw beef and raw milk and raw milk cheese manufactured from cows’ milk, and also evaluated available evidence for other small ruminants, swine and other animals. The information is presented from primary production, to the end of processing, providing the reader with information on the currently available interventions based on the latest scientific evidence. This work was undertaken to support the development of guidelines for the control of STEC in beef, raw milk and cheese produced from raw milk by the Codex Committee on Food Hygiene (CCFH).
Shiga toxin-producing Escherichia coli (STEC) infections are a substantial public health issue worldwide, causing more than 1 million illnesses, 128 deaths and nearly 13 000 Disability-Adjusted Life Years (DALYs) annually. To appropriately target interventions to prevent STEC infections transmitted through food, it is important to determine the specific types of foods leading to these illnesses. An analysis of data from STEC foodborne outbreak investigations reported globally, and a systematic review and meta-analysis of case-control studies of sporadic STEC infections published for all dates and locations, were conducted. A total of 957 STEC outbreaks from 27 different countries were included in the analysis. Overall, outbreak data identified that 16% (95% UI, 2-17%) of outbreaks were attributed to beef, 15% (95% UI, 2-15%) to produce and 6% (95% UI, 1-6%) to dairy products. The food sources involved in 57% of all outbreaks could not be identified. The attribution proportions were calculated by WHO region and the attribution of specific food commodities varied between geographic regions. In the European and American sub-regions of the WHO, the primary sources of outbreaks were beef and produce. In contrast, produce and dairy were identified as the primary sources of STEC outbreaks in the WHO Western Pacific sub-region. The systematic search of the literature identified useable data from 21 publications of case-control studies of sporadic STEC infections. The results of the meta-analysis identified, overall, beef and meat-unspecified as significant risk factors for STEC infection. Geographic region and age of the study population contributed to significant sources of
Enterohemorrhagic E. coli (EHEC) are responsible for important diseases such as hemorrhagic colitis,hemolytic and uremic syndrome or thrombotic thrombocytopenic purpura. Human infections occurprincipally by consumption of contaminated food particularly beef meat, milk or vegetables. The mainnaturally reservoir of EHEC is the gastro-intestinal tract of cattle. Cattle feces are therefore responsiblefor contamination of various types of food but also environment dissemination of the pathogenicbacteria. Related to this problematic, the two objectives of this project were (i) to develop a newimmuno-capture method to improve the isolation of the main serogroups of EHEC involved in humaninfections in food; and (ii) to develop a new direct fed microbial usable in cattle to decrease prevalenceof EHEC in animals. This thesis allowed the development of an immuno-capture method based on theuse of 96-well microplates coated with specific antibody directed against E. coli O157 and otherserogroups. This method, called immuno-microplate capture (IMC) was efficient and user-friendly forthe isolation of E. coli O157; O26; O103 and O111 in foods. This could be an alternative to the use ofimmuno-magnetic beads which are currently used for the detection of EHEC in foods, but are timeconsumingand labor intensive when large number of samples is analyzed simultaneously. The secondpart of this thesis allowed the selection of 5 lactic acid bacteria strains which presented highantagonistic activity against E. coli O157 and other serogroups in vitro. Resistance of these strains togastro-intestinal conditions (acidic conditions, presence of bile salts and rumen fluid) was evaluated invitro. The safety of the 5 strains was checked in Balb-C mice by administration of each strain mixed infeed at 109 cfu/g. Finally, freeze-drying did not affect the antagonistic activity of the 5 strains, suggesteda possible large scale use of these strains. According to the various results obtained in vitro, the 5 strainscould potentially be used as DFM in cattle to decrease colonization of their gastro-intestinal tract byEHEC and consequently decrease the risk of food and environment contaminations.
Strains of pathogenic Escherichia coli that are characterized by their ability to produce Shiga toxins are referred to as Shiga toxin-producing E. coli (STEC). STEC are an important cause of foodborne disease and infections have been associated with a wide range of human clinical illnesses ranging from mild non-bloody diarrhoea to bloody diarrhoea (BD) and haemolytic uraemic syndrome (HUS) which often includes kidney failure. A high proportion of patients are hospitalized, some develop end-stage renal disease (ESRD) and some die. The information requested by CCFH is divided into three main areas: the global burden of disease and source attribution; hazard identification and characterization; and monitoring, including the status of the currently available analytical methods. This report provides an overview of the work undertaken in response to the request from the CCFH and provides the conclusions and advice of the Expert Group based on the currently available information.