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Background Cattle have been identified as a major reservoir of E. coli O157:H7 for human infection; the ecology of the organism in sheep and goats is less understood. This study was carried out to determine prevalence, source of infection, antibiotic resistance and molecular characterization of Escherichia coli O157: H7 isolated from sheep and goat. Methods Systematic random sampling was carried out at Modjo export abattoir, Ethiopia, from November 2012 to April 2013 to collect 408 samples from 72 sheep and 32 goats. Samples collected were skin swabs, fecal samples, intestinal mucosal swabs and the inside and outside part of carcasses as well as carcass in contacts such as workers hands, knife, hook and carcass washing water. Then, samples were processed following standard bacteriological procedures. Non-Sorbitol fermenting colonies were tested on latex agglutination test and the positives are subjected to PCR for detection of attaching and effacing genes (eaeA) and shiga toxin producing genes (stx1 and stx2). All E. coli O157:H7 isolates were checked for their susceptibility pattern towards 15 selected antibiotics. Results E. coli O157:H7 were detected in only 20/408 samples (4.9%). Among these 20 positive samples, 70% (14/20), 25% (5/20) and 5% (1/20) were from sheep, goats and knife samples, respectively. No significant associations were found between carcasses and the assumed sources of contaminations. Of all the 20 isolates virulence genes were found in 10 (50%) of them; 3 (15%) with only the eaeA gene and 7(35%) expressing eaeA and stx2 genes. All the isolates were susceptible to Norfloxacin (NOR) (100%). Conclusions The presence of virulence genes shows E. coli O157:H7 is a potential source of human infection in Ethiopia.

One source of water contamination is the release of wastewater that has not undergone efficient treatment. The aim of this study was to evaluate the reduction obtained with sodium hypochlorite (NaClO), UV and peracetic acid disinfection treatment of Salmonella spp., pathogenic Campylobacter, STEC and bacterial indicators in three full-scale municipal wastewater plants. A general reduction in Salmonella was observed after disinfection, but these bacteria were detected in one UV-treated sample (culture method) and in 33%, 50% and 17% of samples collected after NaClO, UV and PAA disinfection treatments, respectively (PCR method). A better reduction was also observed under NaClO disinfection for the microbial indicators. Independent of the disinfection treatment, E. coli O157:H7 was not detected in the disinfected samples, whereas some samples treated with UV and PAA showed the presence of the stx1 gene. No reduction in the presence of stx2 genes was verified for any of the disinfection treatments. Campylobacter was not detected in any of the analysed samples. The overall results highlight a better reduction in microbiological parameters with a NaClO disinfection treatment in a full-scale municipal wastewater plant compared with UV and PAA. However, the results indicate that a complete and specific monitoring program is necessary to prevent a possible risk to public health.

Tahini is a common food product in the Mediterranean area that is used as a main ingredient in variety of ready-to-eat foods. The objective of the current study was to investigate the inhibitory effect of thyme oil (TO) or cinnamon oil (CO) on E. coli O157:H7 viability in tahini and diluted tahini at different storage temperatures. Addition of 2.0% CO to tahini reduced E. coli O157:H7 numbers by 1.38, 1.79 or 2.20 log10 CFU/mL at 10, 25 or 37 °C, respectively, by 28d. In diluted tahini at 10 °C, no viable cells of E. coli O157:H7 by 21d were detected when 1.0% CO was used. However, at 25 and 37 °C, no viable cells were detected by 14d when CO was added at 0.5% level. Addition of 2.0% TO to tahini, resulted in 1.82, 2.01 or 1.65 log10 CFU/mL reduction in E. coli O 157:H7 numbers was noted at 37, 25 or 10 °C, respectively, by 28d. In diluted tahini, TO at 0.5% or 1.0% induced complete reduction in the viability of E. coli O157:H7 by 28d storage at 37 or 25 °C. At 10 °C, a 3.02 log10 CFU/mL reduction was observed by 28d compared to the initial inoculation level in samples treated with 2.0% TO.

This work studies and models microbial inactivation by high hydrostatic pressure applied to insect protein (Acheta domesticus) enriched gels. The target microbial groups and pathogens studied were total aerobic mesophilic (TAM) bacteria, molds and yeasts (M&Y), Salmonella Typhimurium and Escherichia coli O157:H7. Results indicated that high hydrostatic pressure reduced the microbial load of both, the natural contaminating microorganisms (TAM and M&Y) and the intentionally inoculated pathogenic microorganisms. However, inactivation of the initial microbial load was lower than 5-log reductions. Kinetic inactivation parameters were deduced by using the Weibull distribution function which presented high goodness of fit. Kinetic parameters of the model showed that the most resistant microbial group was total aerobic mesophilic bacteria, followed by E. coli O157:H7, mold and yeast and Salmonella with kinetic parameters of 2.21, 1.58, 1.27, and 0.17 (min × mL/CFU) at 350 MPa, respectively. Regarding the pathogenic microorganisms inoculated in insect protein gels, E. coli O157:H7 may be a good candidate Gram negative target microorganism for high hydrostatic pressure process development, because it usually contaminates these products and was the one with the highest baro-resistance. These reasons support that high-pressure treatments for this type of food should be designed considering this microorganism as a target., The authors acknowledge the financial support of the projects AGL2013-48993-C2-2-R and AGL2017-86840-C2-2-R from the Spanish Ministry of Economy, Industry and Competiveness, FEDER funds.

The aim of this study was to characterize the properties of lactoferrin (LF) obtained in a process developed for its isolation from acid whey derived from the production of fresh curd cheese, using a unique technology of ion-exchange chromatography on CIM&reg, monolithic columns. The freeze-dried lactoferrin samples produced on the pilot plant (capacity 1 m3) were examined for the purity, iron-binding capacity, antibacterial activity, and pH- and temperature-stability. Apo-LF inhibited several tested strains (enterobacteria, Staphylococcus, Streptococcus salivarius) except clostridia, lactic acid bacteria, and bifidobacteria. Sample of LF intentionally saturated with Fe3+ lost its antibacterial activity, indicating the involvement of mechanisms based on depriving bacteria of an iron source. All samples, regardless of the iron-saturation level, exhibited stability in pH range 4.0 to 11.0. LF with higher iron content (A-value = 41.9%) showed better thermal stability. Heat treatment up to 72 &deg, C/3 s did not reduce antimicrobial activity against E. coli O157: H7 tox-. Higher purity (above 91%), higher iron-binding capacity and higher inhibitory activity against E. coli O157: H7 tox- compared to some similar products from the market was observed. These results demonstrate a high potential of monolithic ion-exchange chromatography for industrial processing of acid whey as a source of LF that can be used in new products with high-added value. The upscaling of the process is ongoing on a demonstration plant (10&ndash, 30 m3/day capacity).

This factsheet describes E. coli O157:H7 and how it can be transmitted through foods. NP

The E. coli O157: H7 is an enterohemorrhagic bacteria producing Shiga toxin. It can trigger diseases such as hemolytic uremic syndrome (HUS) and hemorrhagic colitis. It has been found associated with outbreaks of foodborne illness. Therefore, it is important to ensure their absence in the production chain of agroindustrial products through the use of sensitive, fast and specific measurement systems such as PCR. There are currently different methods to identify and quantify E. coli O157: H7 in several matrices, but there is no equivalence or comparability between the results of the measurements produced by these methods, due to the absence of traceable reference materials to the international system of units. In order to contribute to the comparability and traceability of the measures carried out by methods based on nucleic acid amplification, a candidate for reference material (MR) of genomic DNA from E. coli O157: H7 was first made in Colombia. After optimizing the culture and DNA extraction conditions of the microorganism, two batches were prepared with concentrations of 172 ± 30 copies / µL and 164864 ± 13096 copies / µL (Uα=0,95; k=2), they proved to be homogeneous and stable for 3 months. In the characterization of the MR candidate a method was used by digital PCR in droplet mode, validated to detect and quantify E. coli O157: H7 DNA in a measurement range of 8 to 8000 copies/μL with measurement uncertainty between 1.5 to 10% depending on the concentration level. The reference material produced could be used for the quality control of the measurements made by real-time PCR, allowing to establish equivalences between the measurement results obtained by the different commercial tests and guarantee traceability to the international system of units. E. coli O157:H7 es una bacteria enterohemorrágica productora de toxinas Shiga capaz de desencadenar enfermedades como el síndrome urémico hemolítico (SUH) y colitis hemorrágica. Se ha encontrado asociada a brotes de enfermedades transmitidas por alimentos, por lo que es importante garantizar su ausencia en toda la cadena productiva de los productos agroindustriales a través del uso de sistemas de medición sensibles, rápidos y específicos como la PCR. Actualmente hay diferentes métodos para identificar y cuantificar E. coli O157:H7 en varias matrices, pero no existe equivalencia o comparabilidad entre los resultados de las mediciones producidas por estas metodologías, debido a la ausencia de materiales de referencia trazables al sistema internacional de unidades. Con el objetivo de contribuir a la comparabilidad y trazabilidad de las medidas realizadas por métodos basados en la amplificación de ácidos nucleicos, se produjo en Colombia por primera vez un candidato a material de referencia (MR) de ADN genómico de E. coli O157:H7. Luego de optimizar las condiciones de cultivo y extracción de ADN del microorganismo se prepararon dos lotes con concentraciones de 172 ± 30 copias/µL y 164864 ± 13096 copias/µL (Uα=0,95; k=2), los que demostraron ser homogéneos y estables durante 3 meses. En la caracterización del candidato a MR se empleó un método por PCR digital en modo gota, previamente validado para detectar y cuantificar ADN de E. coli O157:H7 en un intervalo de medición de 8 a 8000 copias/μL con incertidumbre de medición entre 1.5 a 10% según el nivel de concentración. El material de referencia producido se podría emplear para el control de calidad de las medidas realizadas por PCR tiempo real, permitiendo establecer equivalencias entre los resultados de medición obtenidos por los distintos ensayos comerciales y garantizar la trazabilidad al sistema internacional de unidades. Ministerio de Ciencias Desarrollo de materiales de referencia o biometrológicos para la detección de Escherichia coli y Salmonella spp. en productos agroindustriales del programa de transformación productiva Línea de Investigación: Bioprocesos Maestría

The persister state is an induced dormancy and has previously been shown to provide cells with temporal antibiotic resistance. In the current study, it was found that the persister state was encountered in toxigenic shiga-toxin Escherichia coli O157:H7 and non-O157. Persister cells exhibited significantly greater tolerance to chlorine, ozone, peroxyacetic acid, and quaternary ammonium compounds, in addition to thermal stress. The revival of persister cells from dormancy depended on the duration of the incubation time post-antibiotic addition. Specifically, revival of persister cells 24 h post-ampicillin addition occurred upon enzymic degradation of the antibiotic. Interestingly, residual ampicillin below the Minimum Inhibitory Concentration (MIC) could maintain the persister state. Persisters incubated for extended periods (8 days) following ampicillin addition eventually became non-culturable and could be revived by removing ampicillin. From the results it can be concluded that the persister state is significant to food safety although to what extent remains to be elucidated.

Escherichia coli O157: H7 is a significant pathogen noted for its virulence and survival tactics associated with fresh produce. The thesis examined the contribution of the persister state within E. coli O157: H7 to increase survival as well as study revival methods. Persister populations were selected by challenging exponentially growing cultures of E. coli O157: H7 to ampicillin followed by an extended incubation period of 8 days. Addition of ampicillin induced a multiphasic die-off pattern with culturable persisters emerging in Phase III and non-culturable in Phase IV. Revival of Phase III persisters required removal of antibiotic pressure while Phase IV required acid-shock treatment. The carbon utilization profile of persister cells was restricted compared to non-persister cells. Persisters also exhibited extended survival in soil microcosms and enhanced tolerance to both UV and chlorine. The study contributes to the knowledge of aspects of the persister state and its significance to food safety.

Improved understanding of pathogen survival in the stream environment is needed to enhance existing predictive models of stream pathogen populations. Further, the increasing use of thermal springs for bathing necessitates additional studies focusedon not only typical streams but also thermal spring conditions, where water temperature is relatively higherthan typical streams. This study was conducted to assess the survival of E. coli O157:H7 and Salmonella Typhimurium in stream water under free floating and particle-attached conditions at a range of temperature. A series of microcosm studies were conducted to determine pathogen decay rates. In bench-scale experiments, water circulation and sediment resuspension mimicked natural streamand thermal spring conditions, with continuous air flow providing aeration, constant mixingand turbulent conditions, and improved water circulation. Data on E. coliO157:H7 and Salmonella survival were subsequently used to determine first-order decay equations for calculating the rate constant and decimal reduction timefor the modeled experimental conditions. Results showed that at 40°C, the survival of particle attached E. coliO157:H7 was longer than that of particle attached Salmonella.Under free floating condition, Salmonella survived longer than E. coliO157:H7. At 50°C, survival of particle attached E. coliO157:H7 and Salmonella was longer than that offree floating E. coli and Salmonella. At 60°C, survival of particle attached Salmonella was longer than that offree floating Salmonella. Similarly at 60 °C, the survival of E. coliO157:H7 under particle attached condition was longer than that ofthe free floating condition.The findings of this study suggest that the survival of E. coli O157:H7 differs than the survival of Salmonella in stream water andthermal spring conditions, and the assumption used in previous studies to estimate survival of bacteria in stream environment could result in over/underestimation if the impact of particleattachment on pathogen survival is not accounted for.

RESUMEN Se evaluó la viabilidad de Lactobacillus plantarum microencapsulado, su efecto de inhibición sobre Escherichia coli O157:H7 y su crecimiento en condiciones gastrointestinales simuladas. Se utilizaron L. plantarum ATCC 8014® y E. coli ATCC 43888®. Se realizaron pruebas de inhibición de L. plantarum sobre E. coli y test de susceptibilidad a CTX (30 µg), P (10 IU), GN (10 µg), DCX (1 µg), CIP (5 µg) y KF (30 µg) para ambas cepas. En la bacteria láctica se determinó la cinética de fermentación y la presencia de péptidos y aminoácidos por HPLC en ambas cepas. Se evaluó el crecimiento a 37 y 45°C de L. plantarum y se valoró la viabilidad de su microencapsulación mediante condiciones gastrointestinales (bilis, sales biliares y pH ácido), al igual que la supervivencia y estabilidad de preparado y sus características físicas y morfológicas. Los resultados indicaron que L. plantarum inhibió a E. coli y el microencapsulado, resultados positivos con una viabilidad del 83,3%; eficiencia de 88,4%; humedad de 7,79%; actividad de agua 0,4; humectabilidad de 1 min, 56 s; solubilidad del 96%; morfología esférica y tamaño entre 15,18 a 35,68 pm. Finalmente, se observó un alto potencial de L. plantarum como agente inhibidor para E. coli O157:H7. ABSTRACT The viability of microencapsulated Lactobacillus plantarum, its inhibition effect on Escherichia coli O157: H7 and growth in simulated gastrointestinal conditions was evaluated. L. plantarum ATCC 8014® and E. coli ATCC 43888® were used. Inhibition tests of L. plantarum on E. coli and susceptibility test to CTX (30 µg), P (10 IU), GN (10 µg) DCX (1 µg), CIP (5 µg) and KF (30) were performed µg) for both strains. In the lactic bacterium the fermentation kinetics were determined, and the presence of peptides and amino acids by HPLC in both strains. The growth at 37 ° C and 45 ° C of L. plantarum was evaluated and the viability of its microencapsulation was assessed by gastrointestinal conditions (Bile, Bile salts and acidic pH), as well as the survival and stability of the preparation and its physical characteristics and morphological. The results indicated that L. plantarum inhibited E. coli and the microencapsulated positive results with a viability of 83.3%, efficiency 88.4%, Humidity 7.79%, water activity 0.4, wettability of 1 min, 56 s, 96% solubility, spherical morphology and size between 15.18 to 35.68 pm. Finally, a high potential of L. plantarum was observed as an inhibitory agent for E. coli O157: H7.

Resumen: El síndrome hemolítico urémico (SHU) asociado a infección intestinal por bacterias productoras de Shigatoxina, que afecta principalmente a población infantil, puede causar morbilidad aguda grave, secuelas crónicas en varios órganos, y la muerte prematura en algunos de ellos. Dado su carácter zoonótico, adecuadas medidas de manejo agropecuario y correcta higiene de lo que consumimos es indispensable a la hora de prevenir la infección. Actualmente, una vez gatillado el SHU el manejo es médico y, principalmente, de soporte. En los últimos años diversas estrategias terapéuticas se han ido desarrollando para evitar que esta enfermedad ocurra, o, al menos, que pueda ser atenuada en sus consecuencias de morbi-mortalidad. El presente artículo describe acciones específicas a diferentes niveles de prevención de esta patología.

Resumen: El síndrome hemolítico urémico (SHU) asociado a infección intestinal por bacterias productoras de Shigatoxina, que afecta principalmente a población infantil, puede causar morbilidad aguda grave, secuelas crónicas en varios órganos, y la muerte prematura en algunos de ellos. Dado su carácter zoonótico, adecuadas medidas de manejo agropecuario y correcta higiene de lo que consumimos es indispensable a la hora de prevenir la infección. Actualmente, una vez gatillado el SHU el manejo es médico y, principalmente, de soporte. En los últimos años diversas estrategias terapéuticas se han ido desarrollando para evitar que esta enfermedad ocurra, o, al menos, que pueda ser atenuada en sus consecuencias de morbi-mortalidad. El presente artículo describe acciones específicas a diferentes niveles de prevención de esta patología. Abstract Hemolytic uremic syndrome (HUS) associated with intestinal infection by Shiga toxin-producing bacteria, which mainly affects children, can cause severe acute morbidity, chronic sequelae in seve ral organs, and premature death in some of them. Given its zoonotic nature, adequate measures of agricultural management and proper hygiene of what we consume are essential to prevent infection. Once the HUS is triggered, medical management is currently mainly supportive. In recent years, va rious therapeutic strategies have been developed to prevent this disease from occurring or, at least, to mitigate its morbidity and mortality consequences. This article describes specific actions at different levels of prevention of this pathology.

Lactic acid bacteria (LAB) are widely used as starter cultures in the preparation of fresh cheeses. These products have been described as good matrices for incorporation of probiotic bacteria, because they have pH close to neutral and high moisture content. These same characteristics can favor the contamination of fresh cheeses by pathogens able to survive under refrigeration, such as Escherichia coli O157:H7. The essential oil (EO) from Origanum vulgare L. (Oregano - OVEO) and Rosmarinus officinalis L. (rosemary - ROEO) may act in synergism against food related bacteria, however, information on its effects on starter cultures and probiotics, or against pathogens during the storage are scarce. The present study evaluated the effects of OVEO and ROEO in synergistic combination on the viable cell counts of the pathogen Escherichia coli O157:H7, the probiotic strain Lactobacillus acidophilus LA-5 and Lactococcus spp., and in fresh cheese over 21 days refrigerated storage (7 ± 0.5 °C). The prevalent OVEO and ROEO terpenes and the physicochemical and sensory aspects that characterize the cheese incorporated of these EOs in synergistic concentrations were also determined during storage. The incorporation of OVEO (0.03 or 0.07 μL/g) and ROEO (1.32 or 2.65 μL/g) in combination in cheeses (produced with the starter or probiotic culture) did not reduce the counts of Lactococcus spp. or L. acidophilus LA-5, while caused a reduction of approximately 3.0 log CFU/g in E. coli O157:H7 counts during the earlier 15 days storage. After this storage time, only a bacteriostatic effect was observed against the pathogen in the cheese. The incorporation of OVEO and ROEO in synergistic combination delayed the increase in counts of both starter and probiotic cultures in cheeses during storage but did not affect the ability of the probiotic strain to survive under simulated gastrointestinal conditions throughout the storage time. A total of 15 OVEO and/or ROEO terpenes were detected in cheeses immediately after production or after 24 h of storage and the amount of all terpenes detected decreased over the 21 days of storage. Eucalyptol, camphor and α-pinene were the terpenes detected in highest amounts in cheeses during the storage time studied. The incorporation of OVEO and ROEO in synergistic concentrations in the cheeses did not affect the yield, or the physical-chemical characteristics of the product. The cheese incorporated of OVEO and ROEO in combination produced with the starter culture was characterized by camphor and mint flavor and greater softness. The sensory scores attributed to aroma, taste, overall impression and purchase intention of probiotic cheese (produced with L. acidophilus LA-5) with OVEO and ROEO increased over the storage. The results show that the incorporation of OVEO and ROEO in synergistic concentrations does not compromise the viability of starter or probiotic culture but is effective to control of E. coli O157:H7 in cheese during refrigerated storage. Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq Bactérias ácido láticas (BAL) são amplamente utilizadas como culturas starter na elaboração de queijos frescos. Estes produtos têm sido descritos como boas matrizes para incorporação de bactérias probióticas, pois possuem pH próximo da neutralidade e elevado teor de umidade. Entretanto, estas características podem favorecer a contaminação de queijos frescos por patógenos capazes de sobreviver sob refrigeração, como Escherichia coli O157:H7. O óleo essencial (OE) de Origanum vulgare L. (orégano - OEOV) e de Rosmarinus officinalis L. (alecrim - OERO) podem atuar em sinergismo contra bactérias de origem alimentar, no entanto, são escassas as informações sobre seus efeitos frente culturas starter e probióticas, ou frente patógenos ao longo do armazenamento. O presente estudo avaliou os efeitos dos OEOV e OERO em combinação nas contagens de células viáveis do patógeno Escherichia coli O157:H7, da cepa probiótica Lactobacillus acidophilus LA-5 e de Lactococcus spp., e em queijo fresco ao longo de 21 dias de armazenamento refrigerado (7 ± 0,5 °C). Os terpenos prevalentes do OEOV e OERO, e os aspectos físico-químicos e sensoriais que caracterizaram o queijo incorporado destes OEs em concentrações sinérgicas também foram determinados durante o armazenamento. A incorporação de OEOV (0,03 ou 0,07 μL/g) e OERO (1,32 ou 2,65 μL/g) em combinação nos queijos (produzidos com a cultura starter ou probiótica) não reduziu as contagens de Lactococcus spp. ou L. acidophilus LA-5, enquanto causou redução de aproximadamente 3,0 log UFC/g nas contagens de E. coli O157:H7 durante os primeiros 15 dias armazenamento. Após esse tempo de armazenamento, apenas um efeito bacteriostático foi observado frente o patógeno nos queijos. A incorporação do OEOV e do OERO em combinação retardou o aumento das contagens da cultura probiótica e de Lactococcus spp. nos queijos durante os 15 dias iniciais do armazenamento, porém não afetou a capacidade da cepa probiótica de sobreviver em condições gastrointestinais simuladas ao longo do armazenamento. Um total de 15 terpenos distintos do OEOV e/ou OERO foram detectados nos queijos imediatamente após a produção, ou após 24 h de armazenamento e a quantidade de todos os terpenos detectados diminuiu durante os 21 dias de armazenamento. Eucaliptol, cânfora e α-pineno foram os terpenos detectados em maior quantidade nos queijos durante todo o tempo de armazenamento estudado. A incorporação de OEOV e OERO em concentrações sinérgicas nos queijos não afetou o rendimento, ou as características físicoquímicas do produto. O queijo incorporado de OEOV e OERO em combinação produzido com a co-cultura Lactococcus lactis subsp. lactis e L. lactis subsp. cremoris foi caracterizado pelo sabor de cânfora e menta e maior maciez. Os escores sensoriais atribuídos ao aroma, sabor, impressão global e à intenção de compra do queijo probiótico (produzido com L. acidophilus LA-5) com OEOV e OERO aumentaram ao longo do armazenamento. Os resultados mostram que a incorporação do OEOV e OERO em concentrações sinérgicas não compromete a viabilidade da cultura starter ou probiótica, porém é eficaz no controle de E. coli O157:H7 em queijo durante o armazenamento refrigerado.

Contamination of fresh produce with pathogenic Escherichia coli, including Shigatoxigenic E. coli (STEC), represents a serious risk to human health. Colonisation is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (two leafy vegetables and two sprouted seed species), is predictive for colonisation of living plants as assessed from growth kinetics and biofilm formation in plant extracts. Fitness of STEC was compared to environmental E. coli, at temperatures relevant to plant growth. Growth kinetics in plant extracts varied in a plant-dependent and isolate-dependent manner for all isolates, with spinach leaf lysates supporting the fastest rates of growth. Spinach extracts also supported the highest levels of biofilm formation. Saccharides were identified as the major driver of bacterial growth, although no single metabolite could be correlated with growth kinetics. The highest level of in planta colonisation occurred on alfalfa sprouts, though internalisation was 10-times more prevalent in the leafy vegetables than in sprouted seeds. Marked differences in in planta growth meant that growth potential could only be inferred for STEC for sprouted seeds. In contrast, biofilm formation in extracts related to spinach colonisation. Overall, the capacity of E. coli to colonise, grow and internalise within plants or plant-derived matrices were influenced by the isolate type, plant species, plant tissue type and temperature, complicating any straight-forward relationship between in vitro and in planta behaviours.Importance Fresh produce is an important vehicle for STEC transmission and experimental evidence shows that STEC can colonise plants as secondary hosts, but differences in the capacity to colonise occur between different plant species and tissues. Therefore, an understanding of the impact of these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined whether growth and the ability of STEC to form biofilms in plants extracts could be related to specific plant metabolites or could predict the ability of the bacteria to colonise living plants. Growth rates for sprouted seeds (alfalfa and fenugreek) exhibited a positive relationship between plant extracts and living plants, but not for leafy vegetables (lettuce and spinach). Therefore, the detailed variations at the level of the bacterial isolate, plant species and tissue type all need to be considered in risk assessment.

Considering the health risks of E. coli O157:H7 presence in food and water, an affordable and highly sensitive detection method is crucial. Herein, we report the first use of a single antibody-based fluorescent lateral flow immunoassay (FLFIA) depending on non-radiative energy transfer between graphene oxide and quantum dots for determination of E. coli O157:H7 in beef and river water. FLFIA showed a high sensitivity rate thousand-fold better than the conventional lateral flow (LF). In inoculated minced beef and river water samples, the limits of detection were 178 and 133 CFU g−1 or mL−1, respectively. Besides, it presented a high selectivity in the presence of other possible interfering bacteria. The single antibody approach reduced the assay cost to 60% less than the conventional LF. Alongside, the results could be read by portable LF readers or smartphones. These advantages offer FLFIA as a promising technology for pathogen detection in food and water., A.H.A. Hassan gratefully acknowledges the financial support from the Science and Technology Development Fund (STDF), Egypt (Grant 25347). E. M.-N. acknowledges the financial support from CONACYT (Mexico, Grant 293523) and National System of Researchers, CONACYT (Mexico, Grant 74314). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant Nos. SEV-2017-0706 and MAT2017) and by CERCA Programme/Generalitat de Catalunya.

Escherichia coli O157:H7 is one of the most important food-borne pathogens to threaten public health. Cultural methods are used as a gold standard while they are laborious and time-consuming. Loop-mediated isothermal amplification (LAMP) method is an alternative method that became widely used for the detection of food-borne pathogens. The aim of this study was to evaluate the specificity and sensitivity of LAMP method for detection of E. coli O157:H7, also to compare detection performances with VIDAS UP and ISO (International Organization for Standardization) methods in different food matrices (beef meat, minced lamb meat, milk, cheese, apple puree, and soybean sprouts). E. coli O157:H7 were spiked in three different levels (high 4.58; medium 2.32; low 0.30 log10 CFU/g-ml) to food matrices. Although there were no significant differences in terms of the specificity and sensitivity values among the three methods (p ≥.05), it was determined that the highest specificity and sensitivity values obtained from the LAMP method. Sensitivity and specificity values of LAMP method were found as 0.997 and 0.988, for the ISO method were 0.989 and 0.971, and for the VIDAS UP method were 0.980 and 0.963, respectively. In milk samples, sensitivity and specificity values of the VIDAS UP method were significantly lower than LAMP and ISO methods (p .05). It can be summarized from this study that specificity and sensitivity values of the LAMP method are equal or higher and less time-consuming than ISO and VIDAS UP methods. In conclusion, using a simple, fast, and inexpensive detection method, such as LAMP, especially in endemic regions or in an outbreak to control spreading of pathogens, is very important for public health. © 2019

Thymol, carvacrol, and trans-cinnamaldehyde are essential oil (EO) compounds with broad-spectrum antimicrobial activities against foodborne pathogens, including Escherichia coli O157:H7. However, little is known regarding direct resistance and cross-resistance development in E. coli O157:H7 after adaptation to sublethal levels of these compounds, and information is scarce on microbial adaptive responses at a molecular level. The present study demonstrated that E. coli O157:H7 was able to grow in the presence of sublethal thymol (1/2T), carvacrol (1/2C), or trans-cinnamaldehyde (1/2TC), displaying an extended lag phase duration and a lower maximum growth rate. EO-adapted cells developed direct resistance against lethal EO treatments and cross-resistance against heat (58°C) and oxidative (50 mM H2O2) stresses. However, no induction of acid resistance (simulated gastric fluid, pH 1.5) was observed. RNA sequencing revealed a large number (310 to 338) of differentially expressed (adjusted P value [Padj ]

The survival of Escherichia coli O157: H7 and Staphylococcus aureus, which are foodborne pathogens was investigated during fermentation and storage of kefir. The kefir grains were inoculated with 5% of the whole fat UHT cow milk and the E. coli O157: H7 and S. aureus cultures were added separately to give 105 cfu mL-1 and left to incubate at 22 °C for 24 hours at first stage. During the incubation, the bacteria and yeast counts, pH and titratable acidity amounts were determined. In the second stage, E. coli O157: H7 and S. aureus cultures were separately added to produce 105 cfu mL -1 of kefir and was stocked at 5 °C for 3 days. Every day samples were taken and the same tests were done. During fermentation, in all samples the initial while TA was 0.14%, the fermentation was 1.0% and 1.01% at the end. The kefir samples were pH 4.5 at the end of the 3 day period of storage. S.aureus was significantly inhibited while E.coli was not inhibited during the fermentation process. During storage, E. coli O157: H7 and S. aureus were inhibited within 2 days. The kefir has the quality of being a healthy product during fermentation and storage.

Despite the increasing reports on the incidence of fresh vegetables and fruits as a possible vehicle for human pathogens, there is currently limited knowledge on the growth potential of Escherichia coli O157:H7 on different plant substrates. This study analyzed the selective adhesion and growth of E. coli O157:H7 on chili habanero (Capsicum chinense L.), cucumber (Cucumis sativus), radish (Raphanus sativus), tomato (Lycopersicon esculentum), beet (Beta vulgaris subsp. vulgaris), and onion (Allium cepa L.) under laboratory conditions. The Gompertz parameters were used to determine the growth kinetics. Scanning electron microscopy was used to visualize the adhesion of E. coli O157:H7 on the epicarp of the samples. Predictive models were constructed to compare the growth of E. coli O157:H7 on the samples with different intrinsic factors and to demonstrate the low selectivity of the pathogen. No significant difference was observed in the lag-phase duration (LPD), generation time (GT), and exponential growth rate (EGR) of the pathogen adhered to the samples. The interaction between the microorganism and the substrate was less supportive to the growth of E. coli O157:H7 for onion, whereas for tomato and cucumber, the time for the microorganism to attain the maximum growth rate (M) was significantly longer than that recorded for other samples.

The antimicrobial effect of citrus extract (at 1 mL/kg [C1] and 2 mL/kg [C2]) on naturally occurring microbiota and inoculated pathogens (E. coli O157:H7 and L. monocytogenes at ca. 6 log cfu/g) in the traditional Greek yogurt-based salad Tzatziki stored at 4, 10, or 21 °C, was examined. Lactic acid bacteria (LAB) were high (8.0–8.5 log cfu/g) and varied only minimally for both the control (untreated) and the citrus extract-treated salad samples, whereas the higher citrus extract concentration yielded the lowest yeast populations, irrespective of temperature, during the entire storage period. Populations of inoculated E. coli (6 log cfu/g) declined in both untreated and citrus extract-treated samples from day 0–70, 35, and 15 at 4, 10, and 21 °C, respectively. Citrus extract had a significant effect on the survival of the inoculated E. coli O157:H7, with reductions of 2.8–4.8 log cfu/g in the citrus extract-treated samples at the end of the storage period. Our data show that L. monocytogenes survived in both untreated and citrus extract-treated samples during the entire storage period, irrespective of the storage temperature. The higher concentration of citrus extract had a significant effect on the survival of L. monocytogenes in the treated samples, and reductions of 1.5–3.0 logs were noted on final day 70, 35 and 15 at 4, 10 and 21 °C, respectively. The results of our study demonstrated the potential of citrus extract as a natural compound that can control the growth of food-borne pathogenic bacteria, such as E. coli O157:H7 and L. monocytogenes in Tzatziki, a yogurt-based salad. Deanship of Scientific Research at King Saud University for funding this research through Research Group Project No. RG-1435-016.

[ES] En el presente trabajo se ha llevado a cabo una evaluación de riesgos semicuantitativa de Escherichia coli O157: H7 en hamburguesa y lechuga lista para su consumo con objeto de evaluar las herramientas Risk Ranger y sQMRA para su aplicación en comedores colectivos en Perú. Los resultados obtenidos indican que la lechuga lista para su consumo presenta un mayor riesgo para el consumidor que la hamburguesa. El riesgo relativo en el Risk Ranger es 62% en la hamburguesa y 69% en la lechuga lista para consumo. En el caso de sQMRA el resultado indica que el porcentaje del total de la población que enfermaría se estima en un 0,9% por consumo de hamburguesa y un 19% en el caso de la lechuga lista para su consumo. Esta herramienta también nos dice que, en el caso de la hamburguesa, el factor que más contribuye en la exposición y el número de casos es la contaminación cruzada, mientras que en la lechuga es el hecho que se consume cruda. En relación al resultado comparativo entre ambas herramientas, se puede decir que no hay diferencias importantes en cuanto a la apreciación del riesgo (riesgo relativo) ni en cuanto al número estimado de enfermos resultante del consumo de ambos alimentos, considerando los parámetros de entrada para ambos modelos, que provienen del estudio y análisis de las bases de datos disponibles. En consecuencia, este estudio nos permite concluir que ambas herramientas son simples y que podrían ser muy útiles para priorizar los riesgos en los comedores colectivos en el Perú. Sin embargo, consideramos que la herramienta sQMRA proporciona más información., [EN] In the present work, a semiquantitative risk assessment of Escherichia coli O157: H7 in hamburger and lettuce ready for consumption was carried out to evaluate the Risk Ranger and sQMRA tools for its application in collective dining rooms in Peru. The results obtained indicate that lettuce ready for consumption presents a greater risk to the consumer than hamburger. The relative risk in the Risk Ranger is 62% in the hamburger and 69% in the lettuce ready for consumption. In the case sQMRA the result indicates that the percentage of the total population that would be sick is estimated at 0.9% for hamburger consumption and 19% in the case of lettuce ready for consumption. This tool also tells us that, in the case of the hamburger, the factor that most contributes to the exposure and the number of cases is cross contamination, while in lettuce it is the fact that it is consumed raw. In relation to the comparative result between both tools, it can be said that there are no important differences in terms of risk assessment (relative risk) or in the estimated number of patients resulting from the consumption of both foods, considering the input parameters for both models, which come from the study and analysis of the available databases. Consequently, this study allows us to conclude that both tools are simple and that they could be very useful to prioritize risks in collective dining rooms in Peru. However, we consider that the sQMRA tool provides more information.

Microbial safety of drinking water constitutes a major concern in countries at all levels of economic development. Thus, rapid, sensitive and cost effective methods of pathogenic bacteria detection, like common Escherichia coli O157:H7, which can cause important diseases, are highly required. In this work an impedimetric transducer modified with E. coli specific aptamer is studied. To enhance the sensitivity a three-dimensional interdigitated electrode array (3D-IDEA) impedimetric transducer, in which the electrodes are separated by insulating barriers was used. In this sensor chemical reactions at the surface of the barrier provoke electrical charge redistribution which causes changes in the surface conductivity. A DNA aptamer, which recognizes specifically the outer membrane proteins of the E. coli O157:H7, was selected as the biorecognition moiety. Here we report a novel label-free impedimetric aptasensor for detection and quantification of pathogenic E. coli O157:H7 with a low detection limit, good selectivity and short detection time. The developed sensor shows a linear response (R2 = 0.977), proportional to the logarithm of bacterial concentration present in the sample, with the limit of detection (LOD) of about 102 cfu mL−1. No response of the aptasensor was registered in the presence of other bacterial strains (E. coli k12, Salmonella typhimurium, Staphylococcus aureus), which confirms the selectivity of the suggested detection method. Additionally, the methodology of the aptasensor regeneration was developed, so that the detection may be performed several times with the same sensor. Moreover, suitability of the aptasensor for bacteria detection in real samples was demonstrated with a new approach involving bacteria pre-concentration., The authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (project CTQ2014-54553-C3-1-R, CTQ2015-66254-C2-2-P and S.B.O fellowship of FPI-MICINN program BES-2015-071250) co-funded by the European Regional Development Fund (Feder) and from the Government of Russian Federation (Grant 074-U01). N.U. acknowledges funding from the People Programme (Marie Curie Actions) of the 7th Framework Programme of the European Union (FP7/2007-2013), TECNIOspring program from the Agency for Business Competitiveness of the Government of Catalonia (ACCIÓ).

Cronobacter sakazakii and Escherichia coli O157:H7 are well known food-borne pathogens that can cause severe disease. The identification of new alternatives to heating to control these pathogens in foods, while reducing the impact on organoleptic properties and nutritional value, is highly desirable. In this study, nisin and its bioengineered variants, nisin V and nisin S29A, are used alone, or in combination with plant essential oils (thymol, carvacrol and trans-cinnamaldehyde) or citric acid, with a view to controlling C. sakazakii and E. coli O157:H7 in laboratory-based assays and model food systems. The use of nisin variants (30 μM) with low concentrations of thymol (0.015%), carvacrol (0.03%) and trans-cinnamaldehyde (0.035%) resulted in extended lag phases of growth compared to those for corresponding nisin A-essential oil combinations. Furthermore, nisin variants (60 μM) used in combination with carvacrol (0.03%) significantly reduced viable counts of E. coli O157:H7 (3-log) and C. sakazakii (4-log) compared to nisin A-carvacrol treatment. Importantly, this increased effectiveness translated into food. More specifically, sub-inhibitory concentrations of nisin variants and carvacrol caused complete inactivation of E. coli O157:H7 in apple juice within 3 h at room temperature compared to that of the equivalent nisin A combination. Furthermore, combinations of commercial Nisaplin and the food additive citric acid reduced C. sakazakii numbers markedly in infant formula within the same 3 h period. These results highlight the potential benefits of combining nisin and variants thereof with carvacrol and/or citric acid for the inhibition of Gram negative food-borne pathogens.

Background There is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia. Methods Various samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods. Results At the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested. Conclusions E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7.

Field trials were conducted in July–August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to romaine lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05 × 107 CFU E. coli O157:H7 (C0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation and seasonal climate effects, sets of lettuce heads (n = 28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (Ct) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (∼5-log reduction) to >3.45 × 1012 MPN/head (∼5-log growth). Relative to C0, on day 10 (Ct = 12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum Ct = 8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (Ct = 12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on romaine lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 h post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of romaine lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.

Although minimal food processing strategies aim to eliminate foodborne pathogens and spoilage microorganisms through a combination of mild preservation techniques, little is actually known on the resistance behavior of the small fraction of microorganisms surviving an inimical treatment. In this study, the conduct of severely heat stressed survivors of E. coli O157:H7 ATCC 43888, as an indicator for the low infectious dose foodborne enterohemorrhagic strains, was examined throughout their resuscitation and outgrowth. Despite the fact that these survivors were initially sublethally injured, they were only marginally more sensitive to a subsequent heat treatment and actually much more resistant to a subsequent high hydrostatic pressure (HHP) shock in comparison with unstressed control cells. Throughout further resuscitation, however, their initial HHP resistance rapidly faded out, while their heat resistance increased and surpassed the initial heat resistance of unstressed control cells. Results also indicated that the population eventually emerging from the severely heat stressed survivors heterogeneously consisted of both growing and non-growing cells. Together, these observations provide deeper insights into the particular behavior and heterogeneity of stressed foodborne pathogens in the context of food preservation. This Document is Protected by copyright and was first published by Frontiers. All rights reserved. https://doi.org/10.3389/fmicb.2016.01845 https://creativecommons.org/licenses/by/4.0/legalcode ispartof: Frontiers in Microbiology vol:7 issue:NOV ispartof: location:Switzerland status: published

Fil: Van der Linden, Inge. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: Ávalos Llano, Karina Roxana. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: Ávalos Llano, Karina R. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fil: Eriksson, Markus. Ghent University. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: De Vos, Winnok H. Ghent University. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: De Vos, Winnok H. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: Van Damme, Els J.M. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: Uyttendaele, Mieke. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. Fil: Devlieghere, Frank. Universidad de Gante. Facultad de Ingeniería en Biociencias; Bélgica. The influence of a selection of minimal processing techniques (sanitizing wash prior to packaging, modified atmosphere, storage conditions under light or in the dark) was investigated in relation to the survival of, attachment to and internalization of enteric pathogens in fresh produce. Cut Iceberg lettuce was chosen as a model for fresh produce, Escherichia coli O157:H7 (E. coli O157) and Salmonella enterica were chosen as pathogen models. Care was taken to simulate industrial post-harvest processing. A total of 50 ± 0.1 g of fresh-cut Iceberg lettuce was packed in bags under near ambient atmospheric air with approximately 21% O2 (NAA) conditions or equilibrium modified atmosphere with 3% O2 (EMAP). Two lettuce pieces inoculated with E. coli O157 BRMSID 188 or Salmonella Typhimurium labeled with green fluorescent protein (GFP) were added to each package. The bags with cut lettuce were stored under either dark or light conditions for 2 days at 7 °C. The pathogens' capacity to attach to the lettuce surface and cut edgewas evaluated 2 days after inoculation using conventional plating technique and the internalization of the bacteria was investigated and quantified using confocal microscopy. The effect of a sanitizing wash step (40 mg/L NaClO or 40 mg/L peracetic acid+1143 mg/L lactic acid) of the cut lettuce prior to packaging was evaluated as well. Our results indicate that both pathogens behaved similarly under the investigated conditions. Pathogen growth was not observed, nor was there any substantial influence of the investigated atmospheric conditions or light/dark storage conditions on their attachment/internalization. The pathogens attached to and internalized via cut edges and wounds, from which they were able to penétrate into the parenchyma. Internalization through the stomata into the parenchyma was not observed, although some bacteria were found in the substomatal cavity. Washing the cut edges with sanitizing agents to reduce enteric pathogen numberswas not more effective than a rinse with precooled tapwater prior to packaging. Our results confirm that cut surfaces are the main risk for postharvest attachment and internalization of E. coli O157 and Salmonella during minimal processing and that storage and packaging conditions have no important effect.

The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (10² and 10(6)log10 cfu/ml)and Lactobacillus plantarum (10² and 10(4)log10 cfu/ml)on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P. fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P. fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7.

Eleven essential oils (EOs) were evaluated for their antibacterial properties, against Vancomycin-Resistant Enterococci (VRE) and E. coli O157:H7. EOs were introduced into Brain Heart Infusion agar (BHI) (15ml) at a concentration of 0.25 to 2% (vol/vol) to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each pathogen evaluated. Results showed that the most active essential oils against bacteria tested were thyme oil, with MIC90 and MBC90 for the VRA strains of 0.25% and 0.5%, respectively. Eucalyptus, juniper and clove oils were the least potent agent, with MIC90 and MBC90 of 2%. Furthermore, the inhibitory effect of these EO were evaluated against VRE and E. coli O157:H7, experimentally inoculated (10(3) cfu/g) in Feta soft cheese and minced beef meat, which was mixed with different concentrations (0.1%, 0.5% and 1%) of the EO and stored at 7 °C for 14 days. Out of eucalyptus, juniper, mint, rosemary, sage, clove and thyme oils tested against target bacteria sage and thyme showed the best results. Clove and mint did not show any effect on VRE and E. coli O157:H7 in both kinds of studied foods. The addition of thyme oil at concentrations of 0.5 and 1% caused best significant reduction in the growth rate of VRE and E. coli O157:H7 in cheese and meat at 7 (o)C. It is concluded that selected plant EOs can act as potent inhibitors of both microorganisms in a food product. The results revealed the potential of thyme oil as a natural preservative in feta soft cheese and minced beef meat against VRE and E. coli O157:H7 contamination.

Many uncontrolled studies and a subsequent meta-analysis suggest that hemolytic uremic syndrome (HUS) with a positive history for diarrhea is associated with a significant increase in chronic renal disease. Two recent controlled studies that followed children with this type of HUS after Escherichia coli O157:H7 outbreaks, and where the controls were selected from a group exposed in the outbreak, gave conflicting results. To clarify this apparent difference, we retrospectively compared a cohort of 30 children with sporadic diarrhea-positive HUS with 30 healthy controls who had no history of bloody diarrhea or HUS and who had similar age and gender. Significantly more children with previous HUS than the controls had albuminuria over a median follow-up of 6.2 years. Of these albuminuric patients, one-third had macroalbuminuria compared with none of the controls. Following HUS, children were three times more prone to hypertension and prehypertension, although the difference was not statistically significant. Glomerular filtration rates, estimated by cystatin C, were significantly lower by 30 ml/min/1.73m 2. Thus, children with sporadic HUS with positive history of diarrhea compared with unexposed controls had a higher prevalence of chronic renal disease; results consistent with the meta-analysis. Prospective studies with appropriate controls are needed to completely resolve this issue. © 2010 International Society of Nephrology.

Three hundred rectal faecal samples and 213 raw milk samples obtained from the tanks and containers were examined using standard cultural methods. Escherichia coli O157:H7 was isolated from 11 (3.7 %) of 300 faecal samples and 3 (1.4 %) of 213 raw milk samples. It was determined that 8 (73 %) of E. coli O157:H7 strains isolated from faecal samples originated from water buffaloes younger than 2 years of age and 3 (27 %) from 2-year-old and older water buffaloes. This is the 1st isolation of Escherichia coli O157:H7 from faecal and milk samples of water buffaloes in Turkey.

Escherichia coli O157:H7 is the main causative agent of haemolytic uremic syndrome. Cattle are the main reservoir of these bacteria, and have been shown to develop immune response to colonization. Our aim was to investigate the faecal shedding pattern of E. coli O157:H7 in calves challenged intragastrically with either 108 or 1010 CFU, as well as the ability of specific preexisting antibodies to reduce shedding of the pathogen. Shedding was analysed by direct counting as well as enrichment of rectoanal mucosal swabs. Statistical analysis was performed using a linear model for repeated measures with and without the inclusion of preexisting antibodies against the carboxy-terminal fraction of intimin- (-intimin C280) as a covariable. Results suggest that there is a statistical difference in the area under the shedding curves between both doses for 14 as well as 28 days after challenge (p = 0.0069 and 0.0209, resp.). This difference is increased when the prechallenge antibodies are taken into account (p = 0.0056 and 0.0185). We concluded that the bacterial dose influences shedding on calves experimentally challenged and that preexisting antibodies against E. coli O157:H7 -intimin C280 could partially reduce faecal excretion. Fil: Martorelli, Luisina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Hovde, C. J.. University Of Idaho; Estados Unidos Fil: Vilte, D. A.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; Argentina Fil: Albanese, A.. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas. Laboratorio de Fisiopatogenia; Argentina Fil: Zotta, E.. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas. Laboratorio de Fisiopatogenia; Argentina Fil: Ibarra, Cristina Adriana. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas. Laboratorio de Fisiopatogenia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cantet, Rodolfo Juan Carlos. Universidad de Buenos Aires. Facultad de Agronomia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Mercado, E. C.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; Argentina Fil: Cataldi, Angel Adrian. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Escherichia coli O157:H7 é um agente patogénico emergente, associado com o decorrer de inúmeros surtos de origem alimentar um pouco por todo o mundo. Na origem desses surtos estão associados vários alimentos: leite, legumes crus tais como alfaces e espinafres, no entanto, a carne tem sido reportada como o principal veículo de transmissão desta estirpe. O contato pessoa-pessoa e a ingestão de água contaminada são também outras formas de contágio associadas ao dito microrganismo. A sintomatologia das infeções causadas por E. coli O157:H7 pode variar desde diarreias leves a severas e sanguinolentas, podendo em alguns casos mais graves evoluir para o Síndrome Urémico Hemolítico. A carne é um meio ideal para o crescimento de microrganismos devido à sua composição. Aliado a este facto, a elevada manipulação com baixo padrão higiénico-sanitário pode ter um importante contributo na sua inocuidade facilitando o crescimento e desenvolvimento microbiano. Desta forma, este trabalho teve como principal objetivo a implementação e validação do Método Horizontal de Deteção de Escherichia coli O157:H7, com algumas alterações, em 15 amostras de carne (ISO 16654-2001). No referido método foi utilizado o caldo de triptona de soja modificada com a adição de novobiocina (mTSB+N) como meio de enriquecimento. Posteriormente procedeu-se à inoculação nos meios seletivos CT-SMAC e chrom ID O157:H7 onde foi avaliada a presença de colónias características. Entre as 15 amostras, três foram identificadas com a presença de colónias típicas do microrganismo, pelo que se seguiram testes confirmativos, nomeadamente a produção de indol (positiva) e a aglutinação com anti-soro para E. coli O157:H7 (positivo). Paralelamente a este método foi realizado o método de PCR e VIDAS® UP E. coli O157 (including H7) (ECPT), atualmente em vigor no laboratório da SGS, de forma a averiguar a concordância de resultados entre as três metodologias.

Grape seed extract (GSE) and peanut skin extract (PSE) are waste products in the wine and peanut industries. Both extracts have high concentrations of polyphenols, known to possess antioxidant and antimicrobial properties. A subcategory of polyphenol is procyanidin, which can be divided into two types, type A and type B. Type A (PSE), contains two single bonds connecting the phenolic groups while type B (GSE), contains one single bond connecting the phenolic groups. The minimum inhibitory concentration (MIC) of the two extracts was evaluated for their antimicrobial effect on Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium using the pour plate method. GSE was found to have a significantly lower MIC (p ≤ 0.05) than PSE for L. monocytogenes (GSE=60.60ppm, PSE=not found), S. aureus (GSE=38.63ppm, PSE=51.36ppm), and S. Typhimurium (GSE=45.73ppm, PSE=60.60ppm). There was no significant difference in inhibition of E. coli O157:H7 (GSE=47.44ppm, PSE=51.13ppm). Since GSE, contributed to greater pathogen inhibition, its extract was fractionated into monomer and oligomers components. Growth curves of all four pathogens inoculated in the monomer and oligomer fractions were compared using the BioScreen method. Oligomers inhibited growth of L. monocytogenes, S. aureus, and E. coli O157:H7 while monomers inhibited growth of S. Typhimurium. These results indicate that an extract with type B procyanidins that are high in oligomers may be more effective as antimicrobials. Type B procyanidins have also been shown to prevent bacterial adhesion, as is the case with urinary tract infections, and may aid in the prevention of biofilms. Master of Science in Life Sciences

P. 296-302 Entidades financiadoras: Junta de Castilla y León (Ayuda Grupo de Excelencia GR155 y Proyecto de Investigación LE331A12-2). Proyecto de Investigación AGL2011-26118/ALI. The antimicrobial activity of two packaging films (polypropylene –PP- and polyethylene terephthalate –PET-) coated with different concentrations (0, 4, 6 and 8%) of essential oil from Origanum vulgare (OR) and Ethyl Lauroyl Arginate HCl (LAE) was tested against two E. coli O157:H7 strains using in vitro systems and a raw milk sheep cheese model (Zamorano). The influence of the antimicrobials on the sensory attributes of cheese was also evaluated. For both strains, the MBC (minimum bactericidal concentration) values were identical to their respective MIC (minimum inhibitory concentration) values and lower for LAE (25 mg/l) than for OR (200-400 mg/l). PP and PET films coated with OR were tested by a vapour phase assay and the Japanish Standard method (JIS Z 2801:2000). Both films coated with LAE were tested by an agar diffusion method. Overall, in vitro tests were effective against both strains. The inhibitory activity depended on the active compound concentration, the target strain and the packaging material, PET being more effective than PP. For inoculated cheese slices, OR and LAE PP films did not effectively decrease E. coli O157:H7 counts after 7-days cold storage. PET films incorporating 6 and 8 % of OR and LAE significantly (p< 0.05) decreased the numbers of both strains and also did 4% for the reference and wild strain depending on the antimicrobial. LAE PP, OR PET and LAE PET did not significantly (p> 0.05) affect sensorial characteristics of Zamorano cheese. Packaging with PET films coated with  6% LAE concentrations might be useful in reducing E. coli O157:H7 numbers in sheep cheese

WOS: 000344690200021, In this study, the presence of Escherichia coli (E. coli) O157:H7 was investigated in minced meat samples. E. coli O157:H7 was detected in six (7.5%) of the minced meat samples. Examination of the positive isolates for the presence of virulence genes; stx1 was determined in one isolate, stx2 in three isolates and both stx1 and stx2 were found in one isolate. Also eae genes were observed in all the positive isolates.

Having access to piped water on premises is commonly related to clean and safe drinking water, in both developed and developing countries. Even though relatively few studies have been done on the subject, they show poor drinking water quality have been associated with piped water on premises. In some cases, the water quality from piped water at the point of use is unsafe for consumption than other water sources such as private boreholes and wells used by the people. The main reason for the poor quality of piped water on premises is the contamination of water in the distribution network of the water supply system. Several waterborne disease outbreaks have been associated with the contamination of the water distribution network. The purpose of this study was to compare the water quality and assess the microbial health risk for piped water in slum and non-slum areas. The study was conducted in Kumasi, Ghana. Ten sampling points were selected from each area and a total 166 water samples were collected over a period of five weeks 79 from the slum area and 87 from the non- slum area. The study assessed the levels of Escherichia coli, Escherichia coli O157:H7 and Salmonella in the water samples. This study showed that 25.9% (43/116) of the samples contained Escherichia coli, 19% (15/79) in the slum area and 32% (28/87) in the non- slum area. Escherichia coli O157:H7 was only detected in one sample from the slum area and none from the non-slum area throughout the study period. Salmonella was not detected in any of the samples in both study areas. By applying the extrapolation method, the risk of being infected by the norovirus was set to 4.86 x 10−3 for the slum area and 7.02 x 10−3 for the non- slum area. The risk for being infected by E. coli O157:H7 was 1.24 x 10−8 for the slum area and 2.19 x 10−8for the non-slum area. At last the risk of being infected by salmonella in the slum area was respectively 3.18 x 10−7 and 5.51 x 10−7 in the nonslum. Because of the poor water quality, recommendation for further investigations and studies is suggested, and investment in the old pipe network is necessary due to the poor water quality delivered to consumer trough the distribution system can cause health risk to the population in Kumasi. M-VM

Escherichia coli O157:H7 é um dos patógenos alimentares mais importantes da atualidade, e, recentemente, diversas cepas desse microrganismo foram isoladas no sul do Brasil. O objetivo deste trabalho foi caracterizar duas cepas de E. coli O157:H7, através da avaliação de sua resistência térmica, ácida e comportamento frente a diferentes desinfetantes e procedimentos de higienização de vegetais folhosos. Resultados demonstraram a redução significativa das contagens bacterianas, após 3 minutos a 60ºC, 2 minutos a 65º, 1 minuto a 70, 72º C e 75ºC. Contudo, após adaptação ácida, nenhuma das cepas foi inativada a 60ºC, por até 3 minutos. A 70ºC foi observado aumento significativo da resistência térmica apenas para a CC. Em relação à resistência ácida, ambas as cepas sobreviveram quando expostas ao meio TSBm a diferentes pH entre 2,0 a 9,5 ajustados com ácido clorídrico e ácido propiônico (AP). Apenas, o meio com pH 2,0, ajustado com AP, foi capaz de reduzir significativamente às contagens de ambas as cepas. Na avaliação da resistência aos desinfetantes, álcool etílico (96ºGl e 70%) e quaternário de amônio foram capazes de inativar ambas as cepas, mesmo na presença de matéria orgânica. O ácido orgânico, na concentração recomendada pelo fabricante e o dobro dessa concentração, reduziu cerca de 90% das contagens, após 5 minutos de exposição. O dicloroisocianurato de sódio só apresentou reduções significativas quando foram utilizadas duas vezes a concentração recomendada pelo fabricante. Todos os procedimentos de lavagem e desinfecção de alfaces, artificialmente contaminadas com E. coli O157:H7, reduziram as contagens em 2,97±1,21logUFC/g, apenas o tratamento conduzido a 10ºC, diferiu significativamente dos demais, apresentando maior redução 6,27±0,50logUFC/g. Esses resultados demonstram que as cepas de E. coli O157:H7 foram resistentes a diferentes situações de estresse, sendo portanto importantes do ponto de vista epidemiológico, visto que estão presentes no sul do Brasil e podem se tornar agentes etiológicos de surtos alimentares. Escherichia coli O157:H7 is a major food pathogens today, and recently, several strains of this organism were isolated in southern Brazil. The objective of this study was to characterize two strains of E. coli O157: H7, by evaluating its thermal and acid resistance and behavior among different disinfectants and cleaning procedures on leafy vegetables. The results showed a significant reduction in bacterial counts after 3 minutes at 60 ° C, 2 min at 65 ° and 1 min at 70, 72 º C and 75 º C. However, after acid adaptation, none of the strains was inactivated at 60 ° C among 3 minutes. At 70 ° C significant increase in heat resistance was observed only for CC. Regarding acid resistance, both strains survived when exposed to TSBm medium at different pH adjusted from 2.0 to 9.5 with hydrochloric acid and propionic acid (PA). Only when the medium was adjusted with AP at pH 2.0 it was able to significantly reduce the counts of both strains. Evaluating the resistance to disinfectants, Ethyl Alcohol Free (96ºGl and 70 %) and quaternary ammonium were able to inactivate both strains, even in the presence of organic matter. For the orgnic acid in the concentration recommended by the manufacturer and at the double concentration there was reduced around 90 % of the counts after 5 minutes of exposure. The sodium dichloroisocyanurate only showed significant reductions when used in the double concentration recommended by the manufacturer. All procedures for cleaning and disinfecting the lettuces artificially contaminated with E. coli O157 : H7 counts decreased by 2.97 ± 1.21 log CFU / g , only the treatment conducted at 10 ° C reduced significantly from the others (6 , 27 ± 0.50 log CFU / g). The results demonstrate that the strains of E. coli O157 : H7 were resistant to different stress situations and therefore are important as an epidemiological point of view, as it is present in southern Brazil and can become etiologic agents of food borne outbreaks.

Escherichia coli O157:H7 is a pathogen strain, which causes hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura in humans. The control of bacterial cells in foods is an important factor to reduce foodborne diseases due to E. coli O157:H7. Assays to inactivate E. coli O157:H7 were carried out by using the cinnamon oil obtained by steam distillation for 6 hours. When E. coli O157:H7 cells were incubated at 37 degrees C for 2 hours in the presence of 0.025% of the essential oil from cinnamon, a dramatic decrease was observed in the viable counts (from 10(7) to 3.10(4) CFU/mL-1). In the presence of 0.05% of the oil, most of cells were killed after 30 min, suggesting that the antimicrobial activity of essential oil is bactericidal against E. coli. The minimal inhibitory concentration of the essential oil from cinnamon was around 625 ppm against E. coli O157:H7 and E. coli ATCC 25921, around 1250 ppm against E. coli ATCC25922 and around 2500 ppm against E. coli ATCC11105.

[ES] Investigadores e industriales trabajan en el desarrollo de nuevas formulaciones y procesos que garanticen la calidad y la seguridad de los alimentos. En el ámbito de las nuevas formulaciones, los subproductos de la industria alimentaria representan una potencial fuente de materias primas económicas, y ricas en componentes bioactivos, cuyas propiedades tecnológicas y antimicrobianas se encuentran todavía escasamente estudiadas. En este contexto se plantea el objetivo del presente estudio, evaluar las propiedades antimicrobianas de tres subproductos cítricos; mandarina, naranja y limón, frente a dos patógenos de especial interés para la industria agroalimentaria Salmonella typhimurium y Escherichia coli O157:H7, en medio de referencia, bajo diferentes condiciones de incubación: temperatura [5-22] ºC y concentración de subproducto [0.5-10] % (p/v). De los resultados obtenidos se concluye que todos los subproductos presentan efecto bacteriostático y/o bactericida bajo las condiciones estudiadas, siendo el subproducto de mandarina más efectivo frente a los microorganismos considerados. Los valores máximos de reducción en ambas poblaciones microbianas tras la exposición a un 5 % (p/v) de mandarina, alcanzan niveles de ¿8 ciclos log10 en refrigeración (5ºC) para S. typhimurium y 1.60 ciclos log10 para E.coli O157:H7, a temperatura ambiente (22ºC). De los estudios llevados a cabo en la presente tesina de máster se concluye que los subproductos cítricos presentan capacidad antimicrobiana efectiva, pudiendo actuar como barrera a la proliferación microbiana, adicionados, por ejemplo, a bebidas pasteurizadas, prolongando la vida útil de las mismas en refrigeración, contribuyendo además a cumplir con objetivos de residuo cero marcados por la Unión Europea., [EN] Scientific researchers and food processors are working in the development of new formulations and new technologies to ensure the quality and safety of food products. In the area of the new formulations, by-products from the food industry are a potential source of inexpensive raw materials, and rich in bioactive components whose technological and antimicrobial properties are still scarcely studied. In this context there is focused the objective of the present study, to evaluate the antimicrobial properties of three citrus byproducts, tangerine, orange and lemon, against two pathogens of particular interest to the food industry Salmonella typhimurium and Escherichia coli O157: H7, in reference medium, under different incubation conditions: temperature and by-products concentration. According to obtained results, it can be concluded that all citric by-products showed bacteriostatic and / or bactericidal effect under the studied conditions, being the tangerine byproduct more effective against considered microorganisms. Maximum reduction levels in both microbial populations achieved values of 8 log10 cycles for S. typhimurium at refrigeration temperature (5ºC) and 1.60 log10 cycles for E.coli O157: H7 at room temperature (22ºC). From the studies carried out in this master thesis it can be concluded that citrus by-products have effective antimicrobial activity, and may act as a barrier to microbial growth added to pasteurized beverages, e.g prolonging their shelf-life under refrigeration, and in addition contributing to meet zero waste targets set by the European Union., [CA] Investigadors i industrials treballen en el desenvolupament de noves formulacions i nous processos que garanteixquen la qüalitat i la seguretat dels aliments. En l'àmbit de les noves formulacions, els subproductes de la indústria alimentària representen una potencial font de matèries primes econòmiques, i riques en components bioactius, quines propietats tecnològiques i antimicrobianes es troben encara escassament estudiades.En aquest context es planteja l'objectiu del present estudi, avaluar les propietats antimicrobianes de tres subproductes cítrics; mandarina, taronja i llimona, davant de dos patògens d'especial interès per a la indústria agroalimentària Salmonella typhimurium i Escherichia coli O157: H7, en mig de referència, i sota differents condicions d'incubació: temperatura [5-22] ºC i concentració de subproducte [0.5-10] % (p/v). Dels resultats obtinguts es conclou que tots els subproductes presenten efecte bacteriostàtic i / o bactericida sota les condicions estudiades, sent el subproducte de mandarina més efectiu davant dels microorganismes considerats, Els valors màxims de reducció en ambdues poblacions microbianes arriben a nivells de 8 cicles log10 per S. typhimurium en condiciones de refrigeració (5ºC) i 1.60 cicles log10 per E.coli O157: H7 a temperatura ambient (22ºC). Dels estudis duts a terme en aquesta tesina de màster es conclou que els subproductes cítrics presenten capacitat antimicrobiana efectiva, i poden actuar com a barrera a la proliferació microbiana adicionats, per exemple, a begudes pasteuritzades, perllongant la vida útil de les mateixes en refrigeració, contribuint a més a complir amb objectius de residu zero marcats per la Unió Europea.

The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages. Data presented in this study provided the initial idea for a novel methodology that was developed in the laboratory of the corresponding author with funding support from University of Manchester Intellectual Property (UMIP). Jordi Bella is listed as an inventor on a patent application protecting the technology (which is not discussed here), filed by the University of Manchester (International Patent Application No PCT/GB2011/052217; Bacterial Collagen, date 14 November 2011).

Contaminated wheat flour has been identified as the probable vehicle of a multi-state outbreak of Escherichia coli O157:H7 associated with ready-to-bake cookie dough. Several cookie dough manufacturers are currently using heat-treated flour for ready-to-bake products, although data on thermal inactivation of foodborne pathogens in wheat flour remains scarce. The objective of this research was to first determine appropriate methods and parameters for bacterial inoculation and thermal treatment of wheat flour, and to subsequently determine the population reductions of E. coli O157:H7 and Salmonella Agona in artificially contaminated wheat flour following thermal treatment for 1, 5, 15 or 30 minutes at 55, 60, 65 or 70°C in a shaking water bath. Flour samples (aw = 0.55) in sterile plastic bags were individually inoculated (~109 CFU/g), pulsified to distribute cultures, and pressed to a uniform thickness (1mm) prior to heat treatment. Following treatment, samples were rapidly cooled and diluted with peptone water; then plated onto Tryptic Soy Agar (TSA) and incubated at 37°C for 24 h prior to enumeration. The minimum heat treatments required for a 5-log reduction in microbial populations (~ 109CFU/g to ~ 104CFU/g) were 5 minutes at 70°C and 30 minutes at 70°C for E. coli O157:H7 and S. Agona, respectively. This research supports the hypothesis that the microbiological safety of ready-to-bake products may be improved by the use of heat-treated flour. Master of Science in Life Sciences

Author(s): Atwill, Edward R.; Jay-Russell, Michele; Li, Xunde; Vivas, Eduardo; Kilonzo, Christopher; Mandrell, Robert | Abstract: Outbreaks of foodborne illness associated with the consumption of leafy green produce from California and across the United States have heightened the need to identify vertebrate sources of these microbial hazards. Concern has focused on wildlife species that have direct access to the produce production environment and irrigation water supplies. Recent fecal surveys of California wildlife, feral animals, and livestock and companion animals are allowing regulators to compare the food safety risks of such pathogens as E. coli O157:H7 and Salmonella from these various animal species. In order to make valid food safety risk comparisons between wildlife, livestock, and companion animals, a variety of methodological and epidemiological issues need to be addressed in order to avoid substantial biases. For example, the amount of feces tested per animal can vary up to a 1000-fold, substantially biasing the probability of testing positive for large fecal contributors (e.g., cattle) compared to smaller wildlife (e.g., deer mice). Many wildlife species intrude and forage as a group in fields of produce, which can lead to in-field defecation, substantially, elevating the risk of microbial contamination compared to many larger animal species that do not have direct access to produce fields due to fencing. This paper highlights the technical challenges of making valid quantitative comparisons of microbial food safety risks from wildlife compared to other domestic animals.

Verocytotoxin-producing Escherichia coli (VTEC) is an important group of emerging food-borne pathogens and represents a major public health concern worldwide. The aim of this work was to analyse faecal samples from hunted wild lagomorphs for the presence of E. coli O157:H7 and non-O157 VTEC. During two hunting seasons, faecal samples from 241 animals were collected, including wild rabbit (Oryctolagus cuniculus) and hare (Lepus granatensis) and were examined for VTEC. Overall, VTEC were detected and isolated in four (1. 66%) of the 241 animals sampled. E. coli O157:H7 was isolated only from one of 124 (0. 81%) wild rabbit faecal samples while non-O157 VTEC were isolated from two of 124 (1. 61%) wild rabbit faecal samples and one of 117 (0. 85%) hare faecal samples. VTEC isolates obtained in the present study (four in total) belonged to four different O:H serotypes, including two serotypes (O84:H- and O157:H7) previously associated with human infection and in particular with causing the life-threatening haemolytic-uraemic syndrome. Although these results indicate a low prevalence of VTEC infection in free-ranging wild lagomorphs, they may play an important role as a source of exposure to human beings and livestock and as a vehicle for dispersing these pathogens. These findings have implications for the zoonotic risk to hunters, people consuming meat from wild animals and others in contact with wild animal faeces, and also in the development of programmes for controlling VTEC at the farm level., This study was partially supported by grants from the Junta de Extremadura and FEDER (grants 3PR05A009-III Plan Regional de Investigación and PRI09A022). R. Martínez acknowledges the Junta de Extremadura for his research fellowship (PRE06053). S. Sánchez acknowledges the Consejería de Educación y Ciencia de la Junta de Comunidades de Castilla-La Mancha and Fondo Social Europeo for his research fellowship (09/02-C).

WOS: 000285440800007 PubMed: 21113101 This study was conducted to investigate the presence of Escherichia (E.) coli O157 and E. coli O157:H7 and stx1 and stx2 genes on cattle carcasses and in rectal samples collected from Samsun Province of Turkey. A total of 200 samples collected from cattle carcasses and the rectal contents of 100 slaughtered cattle from two commercial abattoirs were tested using the immunomagnetic separation technique and multiplex PCR methods. E. coli O157 and E. coli O157:H7 were detected in 52 of the 200 samples (26%) tested. Of the positive samples, 49 were E. coli O157 and three were E. coli O157:H7. The E. coli O157 strain was isolated from 24 carcasses and 25 rectal samples, while E. coli O157:H7 was isolated from two carcasses and one rectal sample. Of the 49 samples positive for E. coli O157,32 were from the rectal and carcass samples of the same animal, while two E. coli O157:H7 isolates were obtained from rectal swabs and carcasses of the same animal. The stx1 and stx2 genes were both detected in 35 E. coli O157 isolates and one E. coli O157:H7 isolate, but the stx2 gene was only detected alone in two E. coli O157 isolates. Overall, 16 carcasses tested positive for E. coli O157 and one carcass tested positive for E. coli O157:H7 based on both carcass and rectal samples. Overall, the results of this study indicate that cattle carcasses pose a potential risk to human health due to contamination by E. coli O157 and E. coli O157:H7 in the feces. Ondokuz Mayis University in Samsun, TurkeyOndokuz Mayis University [Vet-049] This study was part of a doctoral thesis, which was supported by Ondokuz Mayis University in Samsun, Turkey under the Scientific Research Project Program (Project No: Vet-049). The authors also thank Gregory T. Sullivan of Oydem, Ondokuz Mayis University in Samsun, Turkey for editing an earlier version of this manuscript.

La infección por Escherichia coli O157:H7 es causa de diarrea con o sin sangre, colitis hemorrágica y síndrome urémico hemolítico (SUH) en humanos. El principal reservorio animal de E. coli O157:H7 son los bovinos y la carne bovina molida es una potencial fuente de infección. El objetivo de este trabajo fue evaluar un sistema comercial de PCR en tiempo real para la detección de E. coli O157:H7. Se determinó límite de detección, selectividad y robustez. Se contaminaron experimentalmente 50 muestras de carne molida bovina con 10 cepas de E. coli O157:H7 (10, 100 y 1000 UFC/25 g) y 20 cepas de bacterias no-E. coli O157:H7 (1000 UFC/25 g). El límite de detección dependió de la cepa analizada, el valor mínimo fue 6,1 UFC/25 g. La robustez fue óptima al modificar diferentes variables. Se obtuvo 100% de inclusividad y 100% de exclusividad. La técnica evaluada es una alternativa apropiada para la detección de E. coli O157:H7 a partir de carne bovina molida., Shiga toxin-producing Escherichia coli (STEC) cause non-bloody or bloody diar- rhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. Cattle are a major animal reservoir for E. coli O157:H7 and the ground beef are a potential source of infection. The aim of the present study was to evaluate a real time PCR commercial system for detection of E. coli O157:H7. Detection limit, selectivity and robustness were established. Fifty samples of ground beef were experimentally contaminated with 10 E. coli O157:H7 strains (10, 100 y 1000 CFU/25 g) and 20 non-E. coli O157:H7 strains (1000 CFU/25 g). The detection limit depended on the strain analyzed, the minimum values was 6,1 cfu/15 g. A good robustness was observed when different variables were introduced. Inclusivity and exclusivity were of 100%. The evaluated technique is an appropriate alternative for detection of E. coli O157:H7 from ground beef., Facultad de Ciencias Veterinarias