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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.
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).
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.
Bacterial diarrheal diseases remain an important leading cause of preventable death, especially among children under five in developing countries. In the American continent, diarrheal disease and other health complications caused by Escherichia coli constitute a major public health problem, and, therefore, several research groups have dedicated their effort to understand this pathogen and provide feasible solutions to prevent, treat and reduce E. coli infections. The Latin American Coalition for Escherichia coli Research (LACER) was created as a multidisciplinary network of international research groups working with E. coli with the ultimate goal of advancing understanding of E. coli, and to prepare the next generation of American E. coli investigators. As such, this book compiles the knowledge of these investigators about E. coli, a commensal bacteria living inside its host, and a pathogen causing disease in animals and humans. Escherichia coli in the Americas contains a series of 15 chapters written by experts, covering basic concepts regarding the different categories of E. coli, including their environmental niche, virulence mechanisms, host reservoir, and disease outcomes, as well as diagnosis, vaccine development and treatment. This book's target audience include trainees and students learning about the basic and clinical aspects of E. coli pathogenesis, as well as experts around the globe who wish to learn more about this pathogen and the public health impact this bacteria has in America.
Food and Feed Safety Systems and Analysis discusses the integration of food safety with recent research developments in food borne pathogens. The book covers food systems, food borne ecology, how to conduct research on food safety and food borne pathogens, and developing educational materials to train incoming professionals in the field. Topics include data analysis and cyber security for food safety systems, control of food borne pathogens and supply chain logistics. The book uniquely covers current food safety perspectives on integrating food systems concepts into pet food manufacturing, as well as data analyses aspects of food systems. Explores cutting edge research about emerging issues associated with food safety Includes new research on understanding foodborne Salmonella, Listeria and E. coli Presents foodborne pathogens and whole genome sequencing applications Provides concepts and issues related to pet and animal feed safety
During the past three decades, Shiga toxin-producing E.coli (STEC) have emerged as an important food safety concern. Although initially E. coli O157 was the main focus, recent outbreaks and resulting investigations have shown that certain non-O157 STEC are as much a threat to food safety as their O157 counterparts. To the beef industry, STEC have been of particular concern due to the frequent association of beef and beef products as vehicles of STEC infection. As a result, along with E. coli O157, six non-O157 STEC serogroups (known as the ‘big six’) are now regulated as adulterants in certain raw beef products in the United States. Compared to STEC O157, relatively little is known about the prevalence and pathogenicity of the non-O157 STEC in beef production systems. Fecal shedding of STEC by cattle is considered the main route of entry of these pathogens to the environment. The main objective of this study was to investigate if differences existed in the fecal bacterial composition of beef cattle based on their level of STEC shedding. In addition, this study also investigated the fecal prevalence of virulent strains of STEC O157 and the ‘big six’ non-O157 STEC (EHEC-7) within a beef cattle population to assess if the fecal microbiota had an influence on the shedding of these virulent STEC strains. A total of 328 cross-bred beef steers from two separate years were fecal sampled and the fecal bacterial composition assessed using high-throughput DNA sequencing. NeoSEEKTM STEC assay was used to determine the prevalence of EHEC-7. No higher order differences were detected that suggests that STEC shedding was associated with changes in fecal bacterial composition. However, some genera and OTUs were associated with a given shedding category. Only 4.08% of the fecal samples yielded a member of the EHEC-7. The low number of samples positive for EHEC-7 prevented an analysis being done to determine the influence of the fecal microbiota on their shedding.