Literatura académica sobre el tema "Non-STEC Escherichia coli"
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Artículos de revistas sobre el tema "Non-STEC Escherichia coli"
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MATHUSA, EMILY C., YUHUAN CHEN, ELENA ENACHE y LLOYD HONTZ. "Non-O157 Shiga Toxin–Producing Escherichia coli in Foods". Journal of Food Protection 73, n.º 9 (1 de septiembre de 2010): 1721–36. http://dx.doi.org/10.4315/0362-028x-73.9.1721.
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Non-O157 Shiga toxin–producing Escherichia coli (STEC) strains have been linked to outbreaks and sporadic cases of illness worldwide. Illnesses linked to STEC serotypes other than O157:H7 appear to be on the rise in the United States and worldwide, indicating that some of these organisms may be emerging pathogens. As more laboratories are testing for these organisms in clinical samples, more cases are uncovered. Some cases of non-O157 STEC illness appear to be as severe as cases associated with O157, although in general cases attributed to non-O157 are less severe. There is much variation in virulence potential within STEC serotypes, and many may not be pathogenic. Of more than 400 serotypes isolated, fewer than 10 serotypes cause the majority of STEC-related human illnesses. Various virulence factors are involved in non-O157 STEC pathogenicity; the combined presence of both eae and stx genes has been associated with enhanced virulence. A scientific definition of a pathogenic STEC has not yet been accepted. Several laboratories have attempted to develop detection and identification methods, and although substantial progress has been made, a practical method of STEC detection has yet to be validated. Worldwide, foods associated with non-O157 STEC illness include sausage, ice cream, milk, and lettuce, among others. Results from several studies suggest that control measures for O157 may be effective for non-O157 STEC. More research is needed to uncover unique characteristics and resistances of non-O157 STEC strains if they exist. The public health significance of non-O157 STEC and the implications for industry practices and regulatory actions are discussed.
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Paquette, Sarah-Jo, Rahat Zaheer, Kim Stanford, James Thomas y Tim Reuter. "Competition among Escherichia coli Strains for Space and Resources". Veterinary Sciences 5, n.º 4 (2 de noviembre de 2018): 93. http://dx.doi.org/10.3390/vetsci5040093.
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Shiga toxin-producing Escherichia coli (STEC) are a subgroup of E. coli causing human diseases. Methods to control STEC in livestock and humans are limited. These and other emerging pathogens are a global concern and novel mitigation strategies are required. Habitats populated by bacteria are subjected to competition pressures due to limited space and resources but they use various strategies to compete in natural environments. Our objective was to evaluate non-pathogenic E. coli strains isolated from cattle feces for their ability to out-compete STEC. Competitive fitness of non-pathogenic E. coli against STEC were assessed in competitions using liquid, agar, and nutrient limiting assays. Winners were determined by enumeration using O-serogroup specific quantitative PCR or a semi-quantitative grading. Initial liquid competitions identified two strong non-pathogenic competitors (O103F and O26E) capable of eliminating various STEC including O157 and O111. The strain O103F was dominant across permeable physical barriers for all tested E. coli and STEC strains indicating the diffusion of antimicrobial molecules. In direct contact and even with temporal disadvantages, O103F out-competed STEC O157E. The results suggest that O103F or the diffusible molecule(s) it produces have a potential to be used as an alternative STEC mitigation strategy, either in medicine or the food industry.
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SMITH, JAMES L. y PINA M. FRATAMICO. "Effect of Stress on Non-O157 Shiga Toxin–Producing Escherichia coli†". Journal of Food Protection 75, n.º 12 (1 de diciembre de 2012): 2241–50. http://dx.doi.org/10.4315/0362-028x.jfp-12-255.
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Non-O157 Shiga toxin–producing Escherichia coli (non-O157 STEC) strains have emerged as important foodborne pathogens worldwide. Non-O157 STEC serogroups O26, O45, O103, O111, O121, and O145 have been declared as adulterants in beef by the U.S. Department of Agriculture Food Safety and Inspection Service. While documentation is limited, treatments including heat and acid that have been shown to inactivate E. coli O157:H7 will likely also destroy non-O157 STEC; however, non-O157 STEC strains show variability in their responses to stress. It has been shown that non-O157 STEC may survive in fermented sausages and cheeses, and treatments such as high pressure may be necessary to eliminate non-O157 STEC from these products. The mechanisms used by non-O157 STEC to resist acid environments are similar to those used by O157:H7 strains and include the acid tolerance response, the oxidative system, and the glutamate and arginine decarboxylase systems. However, one study demonstrated that some non-O157 STEC strains utilize a chaperone-based acid stress response (HdeA and HdeB) to combat acidic conditions, which is lacking in E. coli O157:H7. Genomic studies suggest that while non-O157 STEC can cause diseases similar to those caused by E. coli O157:H7, O157 and non-O157 STECs have different evolutionary histories. Non-O157 STECs are a heterogeneous group of organisms, and there is currently a limited amount of information on their virulence, fitness, and stress responses, rendering it difficult to draw firm conclusions on their behavior when exposed to stress in the environment, in food, and during processing.
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HUSSEIN, HUSSEIN S. y LAURIE M. BOLLINGER. "Prevalence of Shiga Toxin–Producing Escherichia coli in Beef Cattle". Journal of Food Protection 68, n.º 10 (1 de octubre de 2005): 2224–41. http://dx.doi.org/10.4315/0362-028x-68.10.2224.
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A large number of Shiga toxin–producing Escherichia coli (STEC) strains have caused major outbreaks and sporadic cases of human illnesses, including mild diarrhea, bloody diarrhea, hemorrhagic colitis, and the life-threatening hemolytic uremic syndrome. These illnesses have been traced to both O157 and non-O157 STEC. In a large number of STEC-associated outbreaks, the infections were attributed to consumption of ground beef or other beef products contaminated with cattle feces. Thus, beef cattle are considered reservoirs of STEC and can pose significant health risks to humans. The global nature of the human food supply suggests that safety concerns with beef will continue and the challenges facing the beef industry will increase at the production and processing levels. To be prepared to address these concerns and challenges, it is critical to assess the role of beef cattle in human STEC infections. In this review, published reports on STEC in beef cattle were evaluated to achieve the following specific objectives: (i) assess the prevalence of STEC in beef cattle, and (ii) determine the potential health risks of STEC strains from beef cattle. The latter objective is critically important because many beef STEC isolates are highly virulent. Global testing of beef cattle feces revealed wide ranges of prevalence rates for O157 STEC (i.e., 0.2 to 27.8%) and non-O157 STEC (i.e., 2.1 to 70.1%). Of the 261 STEC serotypes found in beef cattle, 44 cause hemolytic uremic syndrome and 37 cause other illnesses.
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KARCH, HELGE, HANS-IKO HUPPERTZ, JOCHEN BOCKEMÜHL, HERBERT SCHMIDT, ANDREAS SCHWARZKOPF y REINHARD LISSNER. "Shiga Toxin-Producing Escherichia coli Infections in Germany†". Journal of Food Protection 60, n.º 11 (1 de noviembre de 1997): 1454–57. http://dx.doi.org/10.4315/0362-028x-60.11.1454.
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A prospective study was carried out in collaboration with two children's hospitals in Würzburg, Germany to assess the incidence and clinical manifestations of infections due to Shiga toxin-producing Escherichia coli (STEC) in children. Between 1991 and 1995, stool samples from 2788 children with enteritis were investigated for the occurrence of STEC. STEC cultures from stools were screened using PCR with primers complementary to Shiga toxin 1(Stx1) and Shiga toxin 2 (Stx2) genes. PCR-positive samples were further subjected to colony blot hybridization and probe positive colonies were serotyped and analyzed for the presence of virulence genes. There was an increase in the incidence of STEC infections from 0.4% in 1991 to 2.8% in 1994. In 1995 the number of infections remained nearly unchanged (2.5%). Infection with STEC was associated with painful nonbloody diarrhea in most patients. Among the 35 patients in this study with stools containing STEC, only 9 (25.7%) had O157 colonies of which 3 (8.6%) were O157:H7 and 6 (17.1%) were sorbitol-fermenting O157:H−. In an additional study in 1994/l995, STEC etiology in 88 patients with HUS from Germany was confirmed in our laboratories by culture of STEC from stools, and in 20 additional HUS cases by serological analysis. Of the strains from stools of HUS patients, 78% belonged to serogroup O157. The most frequently isolated non-O157 serogroups were O26 and O111. These results demonstrate that when analyzing stools of patients with bloody diarrhea, HUS, or painful nonbloody diarrhea, the occurrence of non-O157:H7 strains should be considered when classical microbiological analysis fails to yield a standard enteric pathogen, such as Campylobacter. E. coli O157:H7, Salmonella. Shigella, or Yersinia.
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CERNICCHIARO, N., D. G. RENTER, C. A. CULL, Z. D. PADDOCK, X. SHI y T. G. NAGARAJA. "Fecal Shedding of Non-O157 Serogroups of Shiga Toxin–Producing Escherichia coli in Feedlot Cattle Vaccinated with an Escherichia coli O157:H7 SRP Vaccine or Fed a Lactobacillus-Based Direct-Fed Microbial†". Journal of Food Protection 77, n.º 5 (1 de mayo de 2014): 732–37. http://dx.doi.org/10.4315/0362-028x.jfp-13-358.
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The objectives of this study were to determine whether fecal shedding of non-O157 Shiga toxin–producing Escherichia coli (STEC) in feedlot cattle was affected by the use of an E. coli O157:H7 vaccine or a direct-fed microbial (DFM) and whether the shedding of a particular non-O157 STEC serogroup within feces was associated with shedding of O157 or other non-O157 STEC serogroups. A total of 17,148 cattle in 40 pens were randomized to receive one, both, or neither (control) of the two interventions: a vaccine based on the siderophore receptor and porin proteins (E. coli SRP vaccine, two doses) and a DFM product (low-dose Bovamine). Fresh fecal samples (30 samples per pen) were collected weekly from pen floors for four consecutive weeks beginning approximately 56 days after study allocation. DNA extracted from enriched samples was tested for STEC O157 and non-O157 serogroups O26, O45, O103, O111, O121, and O145 and for four major virulence genes (stx1, stx2, eae, and ehxA) using an 11-gene multiplex PCR assay. Generalized linear mixed models were used to analyze the effects of treatments and make within-sample comparisons of the presence of O-serogroup–specific genes. Results of cumulative prevalence measures indicated that O157 (14.6%), O26 (10.5%), and O103 (10.3%) were the most prevalent STEC O serogroups. However, the vaccine, DFM, or both had no significant effect (P > 0.05) on fecal prevalence of the six non-O157 STEC serogroups in feedlot cattle. Within-sample comparisons of the presence of STEC serogroup–specific genes indicated that fecal shedding of E. coli O157 in cattle was associated with an increased probability (P < 0.05) of fecal shedding of STEC O26, O45, O103, and O121. Our study revealed that neither the E. coli O157:H7 vaccine, which reduced STEC O157 fecal shedding, nor the DFM significantly affected fecal shedding of non-O157 STEC serogroups, despite the fact that the most prevalent non-O157 STEC serogroups tended to occur concurrently with O157 STEC strains within fecal samples.
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ACHESON, DAVID W. K. "How Does Escherichia coli O157:H7 Testing in Meat Compare with What We Are Seeing Clinically?" Journal of Food Protection 63, n.º 6 (1 de junio de 2000): 819–21. http://dx.doi.org/10.4315/0362-028x-63.6.819.
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Escherichia coli O157:H7 is but one of a group of Shiga toxin-producing E. coli (STEC) that cause both intestinal disease such as bloody and nonbloody diarrhea and serious complications like hemolytic uremic syndrome (HUS). While E. coli O157: H7 is the most renowned STEC, over 200 different types of STEC have been documented in meat and animals, at least 60 of which have been linked with human disease. A number of studies have suggested that non-O157 STEC are associated with clinical disease, and non-O157 STEC are present in the food supply. Non-O157 STEC, such as O111 have caused large outbreaks and HUS in the United States and other countries. The current policy in the United States is to examine ground beef for O157:H7 only, but restricting the focus to O157 will miss other important human STEC pathogens.
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TERAO, YOSHITAKA, KANA TAKESHITA, YASUTAKA NISHIYAMA, NAOKI MORISHITA, TAKASHI MATSUMOTO y FUMIKI MORIMATSU. "Promising Nucleic Acid Lateral Flow Assay Plus PCR for Shiga Toxin–Producing Escherichia coli". Journal of Food Protection 78, n.º 8 (1 de agosto de 2015): 1560–68. http://dx.doi.org/10.4315/0362-028x.jfp-14-495.
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Shiga toxin (Stx)–producing Escherichia coli (STEC) is a frequent cause of foodborne infections, and methods for rapid and reliable detection of STEC are needed. A nucleic acid lateral flow assay (NALFA) plus PCR was evaluated for detecting STEC after enrichment. When cell suspensions of 45 STEC strains, 14 non-STEC strains, and 13 non–E. coli strains were tested with the NALFA plus PCR, all of the STEC strains yielded positive results, and all of the non-STEC and non–E. coli strains yielded negative results. The lower detection limit for the STEC strains ranged from 0.1 to 1 pg of genomic DNA (about 20 to 200 CFU) per test, and the NALFA plus PCR was able to detect Stx1- and Stx2-producing E. coli strains with similar sensitivities. The ability of the NALFA plus PCR to detect STEC in enrichment cultures of radish sprouts, tomato, raw ground beef, and beef liver inoculated with 10-fold serially diluted STEC cultures was comparable to that of a real-time PCR assay (at a level of 100 to 100,000 CFU/ml in enrichment culture). The bacterial inoculation test in raw ground beef revealed that the lower detection limit of the NALFA plus PCR was also comparable to that obtained with a real-time PCR assay that followed the U.S. Department of Agriculture guidelines. Although further evaluation is required, these results suggest that the NALFA plus PCR is a specific and sensitive method for detecting STEC in a food manufacturing plant.
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ENACHE, ELENA, EMILY C. MATHUSA, PHILIP H. ELLIOTT, D. GLENN BLACK, YUHUAN CHEN, VIRGINIA N. SCOTT y DONALD W. SCHAFFNER. "Thermal Resistance Parameters for Shiga Toxin–Producing Escherichia coli in Apple Juice". Journal of Food Protection 74, n.º 8 (1 de agosto de 2011): 1231–37. http://dx.doi.org/10.4315/0362-028x.jfp-10-488.
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The purpose of the present study was to determine the heat resistance of six non-O157 Shiga toxin–producing Escherichia coli (STEC) serotypes in comparison to E. coli O157:H7 in single-strength apple juice without pulp. The thermal parameters for stationary-phase and acid-adapted cells of E. coli strains from serogroups O26, O45, O103, O111, O121, O145, and O157:H7 were determined by using an immersed coil apparatus. The most heat-sensitive serotype in the present study was O26. Stationary-phase cells for serotypes O145, O121, and O45 had the highest D56°C-value among the six non-O157 serotypes studied, although all were significantly lower (P < 0.05) than that of E. coli O157:H7. At 60°C E. coli O157:H7 and O103 demonstrated the highest D-values (1.37 ± 0.23 and 1.07 ± 0.03 min, respectively). The D62°C for the most heat-resistant strain belonging to the serotype O145 was similar (P > 0.05) to that for the most resistant O157:H7 strain (0.61 ± 0.17 and 0.60 ± 0.09 min, respectively). The heat resistance for stationary-phase cells was generally equal to or higher than that of acid-adapted counterparts. Although E. coli O157:H7 revealed D-values similar to or higher than the individual six non-O157 STEC serotypes in apple juice, the z-values for most non-O157 STEC tested strains were greater than those of E. coli O157:H7. When data were used to calculate heat resistance parameters at a temperature recommended in U.S. Food and Drug Administration guidance to industry, the D71.1°C for E. coli O157:H7 and non-O157 STEC serotypes were not significantly different (P > 0.05).
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THRAN, B. H., H. S. HUSSEIN, M. R. HALL y S. F. KHAIBOULLINA. "Shiga Toxin–Producing Escherichia coli in Beef Heifers Grazing an Irrigated Pasture". Journal of Food Protection 64, n.º 10 (1 de octubre de 2001): 1613–16. http://dx.doi.org/10.4315/0362-028x-64.10.1613.
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Shiga toxin–producing Escherichia coli (STEC) produce toxins that have been associated with several human illnesses. E. coli O157:H7 is the most well-studied STEC and was first associated with consumption of improperly cooked ground beef in 1982. E. coli O157:H7 is not the only foodborne STEC because other STEC serotypes are also associated with human illnesses. The objective of this study was to assess prevalence of STEC in 23 yearling beef (Angus) heifers grazing an irrigated grass pasture in spring (April), summer (July), fall (October), and winter (December) of 1999. A total of 86 fecal samples were rectally collected and were subjected to microbiological testing for the presence of STEC. Nine E. coli isolates from five heifers (one in spring and fall and three in winter) were toxic to Vero cells. Of these isolates, four were E. coli O157:H7, two belonged to the serogroup O6, one O39:NM, one O113:H−, and the final isolate was untypable. The STEC prevalence rate in our herd ranged from 4% (spring) to 15% (winter). Based on detecting both O157:H7 and non-O157:H7 STEC in our heifers, it is clear that screening fecal samples should not be limited to E. coli O157:H7. Identification of STEC-positive cattle prior to slaughter should help in reducing the risk of beef contamination with such foodborne pathogens if pre- and/or postharvest control measures are applied to such animals.
Tesis sobre el tema "Non-STEC Escherichia coli"
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Paddock, Zachary Dean. "Shiga toxin producing Escherichia coli (STEC) in cattle: factors affecting fecal shedding of E. coli O157:H7 and detection methods of non-O157 STEC". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/15732.
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Doctor of PhilosophyDepartment of Diagnostic Medicine/Pathobiology
T. G. Nagaraja
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.
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Monaghan, Áine Marie. "Investigations on the serotypes and virulence profiles of non-O157 Shiga-toxin producing Escherichia coli (STEC) and Enteropathogenic Escherichia coli (EPEC) isolated from bovine farms and abattoirs". Thesis, Ulster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695311.
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This study focuses on emerging E. coil serotypes and has developed methods for the isolation and identification of non-0157 STEC and EPEC. A basal medium for the isolation of these pathogens was developed as well as a serogroup specific PCR assay for the detection of the 02 serogroup. These culture and molecular based techniques have proven to be valuable in the detection, identification, and epidemiological investigation of these groups of emerging pathogens. These methods were applied to 1) a farm study, whereby samples (faecal and soil) and 2) an abattoir study, whereby samples (hide and carcass) were analysed for the presence of non-0157 STEC and EPEC. Isolates were subsequently characterised in terms of serotype/serogroup and virulence markers. The data generated by this work has illustrated the extent of non-0157 STEC and EPEC contamination in the farm and abattoir environments, thus providing scientific background upon which control strategies may be based.
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Maurer, Claire Irène. "Contribution à l’étude de l’expression du gène stx2 chez des souches STEC d’origine bovine soumises ou non à des conditions d’induction par l’enrofloxacine". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10201/document.
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Le travail de thèse a eu pour but de contribuer à une meilleure connaissance de la dangerosité pour l’homme des souches STEC d’origine bovine, en explorant la corrélation pouvant exister entre la présence du gène stx chez de telles souches et la réalité de son expression. La quantification de l’expression du gène stx2 présent chez 46 souches STEC bovines a été réalisée à l’aide d’un test ELISA commercial détectant spécifiquement les shiga toxines, le test ProSpecT® Shiga toxin (OXOID). L’ensemble des résultats de validation préalable obtenus pour ce test a permis de considérer qu’il pouvait être valablement appliqué à l’étude du panel de souches d’E. coli O157 :H7 bovines collectées au laboratoire, tout en déterminant les limites méthodologiques, et donc d’interprétation. Utilisé comme outil de quantification de la production de Stx2 par les souches du panel choisi, et dans deux conditions expérimentales différentes (présence ou absence d’induction par l’enrofloxacine), ce test a permis de mettre en évidence que seulement 15,2% des souches d’E.coli O157:H7/H- étudiés produisent des quantités significatives de Stx2 détectables sans induction, et ce à des niveaux variables. En revanche, la majorité de ces isolats, bien que n'exprimant pas la protéine Stx2 de manière constitutive, produit des quantités significatives de Stx2 en présence de concentrations subinhibitrices d'enrofloxacine, antibiotique de la famille des fluoroquinolones et utilisé en médecine vétérinaire. Enfin, des mutants résistants à l'enrofloxacine sélectionnés à partir de certaines souches d’E. coli O157:H7, produisent, après induction par l'enrofloxacine, 3 fois plus de toxine Stx2 que les souches sauvages. Les mutants sont également inductibles en utilisant des doses d'enrofloxacine 100 fois supérieures à celles utilisables pour les souches sauvages. L’ensemble de ces résultats montre (i) la corrélation, ou non, qui peut exister entre la présence du gène stx2 et son expression, (ii) que la proportion inductible des souches STEC bovines est potentiellement importante, (iii) que l’enrofloxacine induit fortement l’expression du gène stx2 chez les souches STEC bovines et que (iv) l’induction par l’enrofloxacine conduit à des taux d’expression du gène stx2 supérieurs chez des souches résistantes aux fluoroquinolones que chez les souches sensibles. Au final, cette étude contribue à documenter la variabilité des niveaux d’expression des gènes stx et illustre le risque que des STEC issus de bovins puissent devenir plus fréquemment pathogènes pour l'homme suite à l'usage croissant des fluoroquinolones vétérinairesThe present study contributed to a better knowledge of the pathogenicity of STEC for humans by quantifying the expression of the stx2 gene from a panel of 46 cattle STEC isolates by ELISA. Succesful validation experiments of the ProSpecT® Shiga toxin ELISA (OXOID) first concluded to its capability to be used for a valuable quantification of the Stx2 protein. Stx2 expression was tested in presence and absence of subtherapeutic concentrations of enrofloxacin, an antibiotic of the fluoroquinolones family used in veterinary medicine. Whereas only 15.2% of the strains displayed significant amounts of detectable Stx2 in absence of induction, most of them were shown to be inducible, and at various levels, in presence of subtherapeutic concentrations of enrofloxacin. Also, enrofloxacin-resistant mutants of Stx2-producing E. coli O157:H7 were selected and produced 3-fold higher Stx2 levels than native strains after induction with enrofloxacin. Mutants were also inducible using hundred-fold higher enrofloxacin concentrations than the useful ones for native strains. At the end, these results show (i) the inconstant and variable expression of the stx2 gene from cattle STEC isolates in native conditions, (ii) the potentially high number of inducible STEC isolates in cattle, (iii) that enrofloxacin is a strong inducer of the stx2 expression in cattle STEC isolates and (iv) that the stx2 gene is stronger induced in isolates resistant to fluoroquinolones compared to susceptible ones. Finally, this all study documents the variable expression of the stx2 gene and also suggests that E. coli O157:H7 from cattle may become more frequently pathogenic to humans as a side-effect of the increasing use of veterinary fluoroquinolones
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Maurer, Claire Irène. "Contribution à l'étude de l'expression du gène stx2 chez des souches STEC d'origine bovine soumises ou non à des conditions d'induction par l'enrofloxacine". Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00652343.
Texto completoResumen
Le travail de thèse a eu pour but de contribuer à une meilleure connaissance de la dangerosité pour l'homme des souches STEC d'origine bovine, en explorant la corrélation pouvant exister entre la présence du gène stx chez de telles souches et la réalité de son expression. La quantification de l'expression du gène stx2 présent chez 46 souches STEC bovines a été réalisée à l'aide d'un test ELISA commercial détectant spécifiquement les shiga toxines, le test ProSpecT® Shiga toxin (OXOID). L'ensemble des résultats de validation préalable obtenus pour ce test a permis de considérer qu'il pouvait être valablement appliqué à l'étude du panel de souches d'E. coli O157 :H7 bovines collectées au laboratoire, tout en déterminant les limites méthodologiques, et donc d'interprétation. Utilisé comme outil de quantification de la production de Stx2 par les souches du panel choisi, et dans deux conditions expérimentales différentes (présence ou absence d'induction par l'enrofloxacine), ce test a permis de mettre en évidence que seulement 15,2% des souches d'E.coli O157:H7/H- étudiés produisent des quantités significatives de Stx2 détectables sans induction, et ce à des niveaux variables. En revanche, la majorité de ces isolats, bien que n'exprimant pas la protéine Stx2 de manière constitutive, produit des quantités significatives de Stx2 en présence de concentrations subinhibitrices d'enrofloxacine, antibiotique de la famille des fluoroquinolones et utilisé en médecine vétérinaire. Enfin, des mutants résistants à l'enrofloxacine sélectionnés à partir de certaines souches d'E. coli O157:H7, produisent, après induction par l'enrofloxacine, 3 fois plus de toxine Stx2 que les souches sauvages. Les mutants sont également inductibles en utilisant des doses d'enrofloxacine 100 fois supérieures à celles utilisables pour les souches sauvages. L'ensemble de ces résultats montre (i) la corrélation, ou non, qui peut exister entre la présence du gène stx2 et son expression, (ii) que la proportion inductible des souches STEC bovines est potentiellement importante, (iii) que l'enrofloxacine induit fortement l'expression du gène stx2 chez les souches STEC bovines et que (iv) l'induction par l'enrofloxacine conduit à des taux d'expression du gène stx2 supérieurs chez des souches résistantes aux fluoroquinolones que chez les souches sensibles. Au final, cette étude contribue à documenter la variabilité des niveaux d'expression des gènes stx et illustre le risque que des STEC issus de bovins puissent devenir plus fréquemment pathogènes pour l'homme suite à l'usage croissant des fluoroquinolones vétérinaires.
Capítulos de libros sobre el tema "Non-STEC Escherichia coli"
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Jaros, Patricia, Muriel Dufour, Brent Gilpin, Molly M. Freeman y Efrain M. Ribot. "PFGE for Shiga Toxin-Producing Escherichia coli O157:H7 (STEC O157) and Non-O157 STEC". En Methods in Molecular Biology, 171–89. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2599-5_15.
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"AOAC Official Method 2017.05 Escherichia coli O157:H7 and E. coli non-O157 Shiga Toxin-Producing E. coli (STEC) in Select Foods". En Official Methods of Analysis of AOAC INTERNATIONAL. 22a ed. New York: Oxford University Press, 2023. http://dx.doi.org/10.1093/9780197610145.003.2216.
Texto completoActas de conferencias sobre el tema "Non-STEC Escherichia coli"
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Kaufmann, Martin, Claudio Zweifel, Jorge Blanco y Roger Stephan. "Prevalence and characteristics of non-O157 shiga toxin-producing Escherichia coli (STEC) and Escherichia coli O157 in fattening pigs at slaughter in Switzerland". En Sixth International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork. Iowa State University, Digital Press, 2005. http://dx.doi.org/10.31274/safepork-180809-775.
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Yoon, Seung Chul, William R. Windham, Scott Ladely, Gerald W. Heitschmidt, Kurt C. Lawrence, Bosoon Park, Neelam Narang y William C. Cray. "Hyperspectral imaging for detection of non-O157 Shiga-toxin producing <i>Escherichia coli</i> (STEC) serogroups on spread plates of mixed cultures". En SPIE Defense, Security, and Sensing. SPIE, 2012. http://dx.doi.org/10.1117/12.919631.
Texto completoInformes sobre el tema "Non-STEC Escherichia coli"
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Rosser, Katy, Iulia Gherman, Erica Kintz, Paul Cook y Anthony WIlson. Assessment of the risk to consumers as a result of disruption to the cold chain during direct supply of Qurbani meat and offal. Food Standards Agency, junio de 2022. http://dx.doi.org/10.46756/sci.fsa.nuc910.
Texto completoResumen
Qurbani is a religious practice that takes place during Eid al-Adha. Consumers practicing Qurbani typically wish to collect meat and red offal within a short time after slaughter, which means these products cannot complete normal chilling processes before leaving the slaughterhouse. This could permit greater growth of pathogens and has the potential to increase the risk of consumer illness. The FSA is working with industry and stakeholder groups to ensure that the risk to consumers under these conditions remains at an acceptable level. To help inform these discussions, the FSA commissioned this assessment to understand the difference in risk from allowing meat and offal to be provided to consumers without the normal chilling process. The microbiological team at the FSA have analysed scientific literature, expert opinion and business and consumer survey data to assess the effect of disrupting the cold chain on pathogens in Qurbani meat. The pathogens that were chosen for inclusion in this assessment are non-typhoidal Salmonella enterica, Shiga toxin-producing Escherichia coli, and Clostridium perfringens. Their growth characteristics and prevalence in beef, lamb and goat meat and offal are discussed. The assessment concluded that given the reported variation in the process, there were two important scenarios with distinct outcomes. In the typical scenario, which is the most likely outcome based on the collected data, there is no significant difference in risk to consumer health compared to normal chilling processes, and the risk level was established as Very Low (“very rare but cannot be excluded”). In a reasonably foreseeable worst-case scenario, Salmonella spp. and STEC levels may increase, presenting an increased risk to the consumer. This risk level was established as Low (“rare but does occur”). We also identified several areas where more evidence would be helpful, and as a result identified a High level of uncertainty in our conclusion.