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Sample records for heat-stabile toxin producing

  1. Heat Stability and Species Range of Purified Staphylococcal α-Toxin

    Science.gov (United States)

    Cooper, Louis Z.; Madoff, Morton A.; Weinstein, Louis

    1966-01-01

    Cooper, Louis Z. (New England Medical Center Hospital, Boston, Mass.), Morton A. Madoff, and Louis Weinstein. Heat stability and species range of purified staphylococcal α-toxin. J. Bacteriol. 91:1686–1692. 1966.—Heating of high-titer purified staphylococcal α-toxin at 60 and 80 C resulted in a double-sloped curve of inactivation of the hemolytic effect on rabbit erythrocytes. Early inactivation was less at the lower temperature, but activity persisted for a longer time at 80 C. Toxin inactivated at 60 C showed renewed activity when heated briefly at 80 C. A precipitate which formed during heating of α-toxin at 60 or 80 C yielded hemolytic activity when resuspended and heated at 80 but not at 60 C. Supernatant fluid of heat-precipitated toxin was heat-labile and did not regain activity when heated at 80 C. The results indicate that the “paradoxical effect” of heating of staphylococcal α-toxin is not due to a thermolabile inhibitor, but results from alteration of the toxin molecule to a heat-stable active form. Demonstration of renewed activity by 80 C heating of purified toxin requires potent toxin preparations and brief heating periods. Hemolysis of erythrocytes of several animal species by purified α-toxin was generally similar to that produced by impure toxin. Rabbit cells were most susceptible. Human and horse erythrocytes hemolyzed to less than 0.1% of the extent of rabbit cells. Blood cells of other species were intermediate in their response to the lytic effect of α-toxin. PMID:5937231

  2. Shiga toxin-producing Escherichia coli

    DEFF Research Database (Denmark)

    Pedersen, Rune Micha; Nielsen, Marc Trunjer Kusk; Möller, Sören

    2018-01-01

    OBJECTIVES: Shiga toxin-producing Escherichia coli (STEC) causes diarrhoeal disease, bloody diarrhoea and haemolytic uraemic syndrome. The aim of this study was to describe the incidence of STEC and the clinical features of STEC patients from a well-defined Danish population in which all fecal...

  3. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Science.gov (United States)

    2012-02-21

    ... Food Safety and Inspection Service Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products... manufacturing trimmings for six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45..., non-intact product, that are contaminated with Shiga toxin-producing Escherichia coli (STEC) O26, O45...

  4. Prevalence and antimicrobial sensitivity of Shiga-toxin-producing ...

    African Journals Online (AJOL)

    Background: Escherichia coli is among the most common causes of diarrhoea in children below five years of age in developing countries. Diarrhoeal diseases rank the second most common cause of morbidity and mortality in developing countries. Here we report the magnitude of Shiga toxin-producing Escherichia coli ...

  5. Tenuazonic Acid, a Toxin Produced by Alternaria alternata1

    Science.gov (United States)

    Meronuck, R. A.; Steele, J. A.; Mirocha, C. J.; Christensen, C. M.

    1972-01-01

    Fifty-seven of 87 isolates of Alternaria alternata (Fr) Keissler grown on autoclaved, moist corn-rice substrate and fed to rats were lethal. The major toxin produced was isolated and characterized as tenuazonic acid. Twenty of 23 toxigenic Alternaria isolates examined produced tenuazonic acid. No tenuazonic acid could be detected in either of the field samples of sorghum or blackeyed peas, which were heavily invaded by Alternaria. PMID:5063203

  6. Characterization of cereulide synthetase, a toxin-producing macromolecular machine.

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    Diego A Alonzo

    Full Text Available Cereulide synthetase is a two-protein nonribosomal peptide synthetase system that produces a potent emetic toxin in virulent strains of Bacillus cereus. The toxin cereulide is a depsipeptide, as it consists of alternating aminoacyl and hydroxyacyl residues. The hydroxyacyl residues are derived from keto acid substrates, which cereulide synthetase selects and stereospecifically reduces with imbedded ketoreductase domains before incorporating them into the growing depsipeptide chain. We present an in vitro biochemical characterization of cereulide synthetase. We investigate the kinetics and side chain specificity of α-keto acid selection, evaluate the requirement of an MbtH-like protein for adenylation domain activity, assay the effectiveness of vinylsulfonamide inhibitors on ester-adding modules, perform NADPH turnover experiments and evaluate in vitro depsipeptide biosynthesis. This work also provides biochemical insight into depsipeptide-synthesizing nonribosomal peptide synthetases responsible for other bioactive molecules such as valinomycin, antimycin and kutzneride.

  7. An Emulsion Based Microarray Method to Detect the Toxin Genes of Toxin-Producing Organisms

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    Yunfei Bai

    2011-08-01

    Full Text Available Toxins produced by bacteria and fungi are one of the most important factors which may cause food contamination. The study of detection methods with high sensitivity and throughput is significant for the protection of food safety. In the present study, we coupled microarray with emulsion PCR and developed a high throughput detection method. Thirteen different gene sites which encode the common toxins of several bacteria and fungi were assayed in parallel in positive and maize samples. Conventional PCR assays were carried out for comparison. The results showed that the developed microarray method had high specificity and sensitivity. Two zearalenone-related genes were investigated in one of the ten maize samples obtained with this present method. The results indicated that the emulsion based microarray detection method was developed successfully and suggested its potential application in multiple gene site detection.

  8. Shiga Toxin (Verotoxin)-Producing Escherichia coli in Japan.

    Science.gov (United States)

    Terajima, Jun; Iyoda, Sunao; Ohnishi, Makoto; Watanabe, Haruo

    2014-10-01

    A series of outbreaks of infection with Shiga toxin (verocytotoxin)-producing Escherichia coli or enterohemorrhagic E. coli (EHEC) O157:H7 occurred in Japan in 1996, the largest outbreak occurring in primary schools in Sakai City, Osaka Prefecture, where more than 7,500 cases were reported. Although the reason for the sudden increase in the number of reports of EHEC isolates in 1996 is not known, the number of reports has grown to more than 3,000 cases per year since 1996, from an average of 105 reports each year during the previous 5-year period (1991-1995). Despite control measures instituted since 1996, including designating Shiga toxin-producing E. coli infection as a notifiable disease, and nationwide surveillance effectively monitoring the disease, the number of reports remains high, around 3,800 cases per year. Serogroup O157 predominates over other EHEC serogroups, but isolation frequency of non-O157 EHEC has gone up slightly over the past few years. Non-O157 EHEC has recently caused outbreaks where consumption of a raw beef dish was the source of the infection, and some fatal cases occurred. Laboratory surveillance comprised prefectural and municipal public health institutes, and the National Institute of Infectious Diseases has contributed to finding not only multiprefectural outbreaks but recognizing sporadic cases that could have been missed as an outbreak without the aid of molecular subtyping of EHEC isolates. This short overview presents recent information on the surveillance of EHEC infections in Japan.

  9. Signature Prediction Modeling in Cytolethal Distending Toxin-Producing Strains

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    Maryam Javadi

    2017-06-01

    Full Text Available In this study, cytolethal distending toxin (CDT producer isolates genome were compared with genome of pathogenic and commensal Escherichia coli strains. Conserved genomic signatures among different types of CDT producer E. coli strains were assessed. It was shown that they could be used as biomarkers for research purposes and clinical diagnosis by polymerase chain reaction, or in vaccine development. cdt genes and several other genetic biomarkers were identified as signature sequences in CDT producer strains. The identified signatures include several individual phage proteins (holins, nucleases, and terminases, and transferases and multiple members of different protein families (the lambda family, phage-integrase family, phage-tail tape protein family, putative membrane proteins, regulatory proteins, restriction-modification system proteins, tail fiber-assembly proteins, base plate-assembly proteins, and other prophage tail-related proteins. In this study, a sporadic phylogenic pattern was demonstrated in the CDT-producing strains. In conclusion, conserved signature proteins in a wide range of pathogenic bacterial strains can potentially be used in modern vaccine-design strategies.

  10. Emergence of Escherichia coli encoding Shiga toxin 2f in human Shiga toxin-producing E-coli (STEC) infections in the Netherlands, January 2008 to December 2011

    NARCIS (Netherlands)

    Friesema, I.; van der Zwaluw, K.; Schuurman, T.; Kooistra-Smid, M.; Franz, E.; van Duynhoven, Y.; van Pelt, W.

    2014-01-01

    The Shiga toxins of Shiga toxin-producing Escherichia coli (STEC) can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) with several sub-variants. Variant Stx(2f) is one of the latest described, but has been rarely associated with symptomatic human infections. In the enhanced STEC

  11. A Fluorescence Based Miniaturized Detection Module for Toxin Producing Algae

    Science.gov (United States)

    Zieger, S. E.; Mistlberger, G.; Troi, L.; Lang, A.; Holly, C.; Klimant, I.

    2016-12-01

    Algal blooms are sensitive to external environmental conditions and may pose a serious threat to marine and human life having an adverse effect on the ecosystem. Harmful algal blooms can produce different toxins, which can lead to massive fish kills or to human disorders. Facing these problems, miniaturized and low-cost instrumentation for an early detection and identification of harmful algae classes has become more important over the last years. 1,2Based on the characteristic pigment pattern of different algae classes, we developed a miniaturized detection module, which is able to detect and identify algae classes after analyzing their spectral behavior. Our device combines features of a flow-cytometer and fluorimeter and is build up as a miniaturized and low-cost device of modular design. Similar to a fluorimeter, it excites cells in the capillary with up to 8 different excitation wavelengths recording the emitted fluorescence at 4 different emission channels. Furthermore, the device operates in a flow-through mode similar to a flow-cytometer, however, using only low-cost elements such as LEDs and photodiodes. Due to its miniaturized design, the sensitivity and selectivity increase, whereas background effects are reduced. With a sampling frequency of 140 Hz, we try to detect and count particular cell events even at a concentration of 2 cells / 7.3 µL illuminated volume. Using a self-learning multivariate algorithm, the data are evaluated autonomously on the device enabling an in-situ analysis. The flexibility in choosing excitation and emission wavelengths as well as the high sampling rate enables laboratory applications such as measuring induction kinetics. However, in its first application, the device is part of an open and modular monitoring system enabling the sensing of chemical compounds such as toxic and essential Hg, Cd, Pb, As and Cu trace metal species, nutrients and species related to the carbon cycle, VOCs and potentially toxic algae classes (FP7

  12. Toxin Profile, Biofilm Formation, and Molecular Characterization of Emetic Toxin-Producing Bacillus cereus Group Isolates from Human Stools.

    Science.gov (United States)

    Oh, Su Kyung; Chang, Hyun-Joo; Choi, Sung-Wook; Ok, Gyeongsik; Lee, Nari

    2015-11-01

    Emetic toxin-producing Bacillus cereus group species are an important problem, because the staple food for Korean is grains such as rice. In this study, we determined the prevalence (24 of 129 isolates) of emetic B. cereus in 36,745 stool samples from sporadic food-poisoning cases in Korea between 2007 and 2008. The toxin gene profile, toxin production, and biofilm-forming ability of the emetic B. cereus isolates were investigated. Repetitive element sequence polymorphism polymerase chain reaction fingerprints (rep-PCR) were also used to assess the intraspecific biodiversity of these isolates. Emetic B. cereus was present in 0.07% of the sporadic food-poisoning cases. The 24 emetic isolates identified all carried the nheABC and entFM genes and produced NHE enterotoxin. However, they did not have hemolysin BL toxin or related genes. A relationship between biofilm formation and toxin production was not observed in this study. The rep-PCR fingerprints of the B. cereus isolates were not influenced by the presence of toxin genes, or biofilm-forming ability. The rep-PCR assay discriminated emetic B. cereus isolates from nonemetic isolates, even if this assay did not perfectly discriminate these isolates. Further study on emetic isolates possessing a high degree of diversity may be necessary to evaluate the performance of the subtyping assay to discriminate emetic and nonemetic B. cereus isolates and could provide a more accurate indication of the risk from B. cereus strains.

  13. The Epidemiology of Travelers’ Diarrhea in Incirlik, Turkey: A Region with a Predominance of Heat-Stabile Toxin Producing Enterotoxigenic Escherichia coli

    Science.gov (United States)

    2010-01-01

    Clyptosporidium parvum, Giardia Iamblia, and Entamoeba histolytica, a colorimetric immunoassay was used-Triage (Biosite, San Diego, CA) (Sharp et al...Parasite Panel for detection of Giardia Iamblia, Entamoeba histo~vticaiEuta­ moeba di.fpw-, and Cryptosporidium parvum in patient stool specimens. J

  14. Shiga toxin-producing Escherichia coli hemolytic uremic syndrome

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    Peco-Antić Amira

    2016-01-01

    Full Text Available The hemolytic-uremic syndrome (HUS is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury (AKI. The major cause of HUS in childhood (>90% is infection with verocytotoxin (Shiga-like toxin - “Stx”-producing bacteria, usually enterohemorrhagic Escherichia coli (VTEC/STEC. The infection may be transmitted by the consumption of undercooked meat, pasteurized dairy products, contaminated vegetables, fruits and water, or by contact with STEC diarrhea. After an incubation period of three to eight days, patients commonly develop bloody diarrhea followed in 5-22% by HUS that may be complicated by central nervous system, pancreatic, skeletal, and myocardial involvement. HUS is one of the main causes of AKI in children in Europe. The management of HUS includes the usual treatment of children with AKI. Transfusion with packed red blood cells is needed in case of a severe anemia, while platelet transfusions are limited to the need for a surgical procedure or in active bleeding. Currently, there is no consensus on the use of antibiotic therapy. Treatment with plasma and/or plasma exchange has not been proven beneficial in STEC-HUS. Eculizumab has been used for the treatment of STEC-HUS, but the value of this treatment remains to be determined. The mortality of HUS is reported to be 3-5%. About 12% of patients will progress to end-stage renal failure within four years and about 25% will have long-term complications, including hypertension, proteinuria, renal insufficiency, and insulin-dependent diabetes mellitus. Transplantation can be performed without increased risk for the recurrence of the disease.

  15. An analytical perspective on detection, screening, and confirmation in phycology, with particular reference to toxins and toxin-producing species.

    Science.gov (United States)

    de la Iglesia, Pablo; Fernández-Tejedor, Margarita; Trobajo, Rosa; Diogène, Jorge

    2013-12-01

    Knowledge concerning the ability of microalgae to produce metabolites of interest such as toxins or high-value secondary metabolites requires exhaustive details to be supplied on how the research was conducted. These should include the microalgal species and strain characterization, the culture conditions, the cell density, and physiological state at the time of harvesting, the harvesting method, the sample pre-treatment protocol, and the subsequent instrumental analytical separation/detection system. In this comment, we discuss issues that affect algal research from an analytical chemistry perspective, particularly (i) the need to specify detection capabilities of the entire method (i.e., limits of detection or threshold detection levels), which we illustrate in relation to classification of a species or strain as being "toxin producing" or "non-toxin producing"; and (ii) the requirements that have to be satisfied to confirm a microalgal species (new or not) as a producer of a particular chemical of interest for phycologists, which again we illustrate in relation to toxins. A successful collaboration among phycologists and analytical chemists will only be achieved as a result of a synergistic collaboration between the two disciplines, with a reciprocal understanding at least at a background level. © 2013 Phycological Society of America.

  16. Sensitivity among species of Solanaceae to AAL toxins produced by Alternaria alternata f.sp lycopersici

    NARCIS (Netherlands)

    Mesbah, LA; van der Weerden, GM; Nijkamp, HJJ; Hille, J

    2000-01-01

    The necrotrophic fungus Alternaria alternata f.sp. lycopersici produces AAL toxins that cause necrosis in tomato tissues with high specificity. Resistance or susceptibility of tomato to the fungus and insensitivity or sensitivity to AAL toxins are determined by a single locus, Asc. In order to

  17. Tolevamer, an anionic polymer, neutralizes toxins produced by the BI/027 strains of Clostridium difficile.

    Science.gov (United States)

    Hinkson, Paul L; Dinardo, Carol; DeCiero, Daniel; Klinger, Jeffrey D; Barker, Robert H

    2008-06-01

    Clostridium difficile-associated diarrhea (CDAD) is caused by the toxins the organism produces when it overgrows in the colon as a consequence of antibiotic depletion of normal flora. Conventional antibiotic treatment of CDAD increases the likelihood of recurrent disease by again suppressing normal bacterial flora. Tolevamer, a novel toxin-binding polymer, was developed to ameliorate the disease without adversely affecting normal flora. In the current study, tolevamer was tested for its ability to neutralize clostridial toxins produced by the epidemic BI/027 strains, thereby preventing toxin-mediated tissue culture cell rounding. The titers of toxin-containing C. difficile culture supernatants were determined using confluent cell monolayers, and then the supernatants were used in assays containing dilutions of tolevamer to determine the lowest concentration of tolevamer that prevented > or =90% cytotoxicity. Tolevamer neutralized toxins in the supernatants of all C. difficile strains tested. Specific antibodies against the large clostridial toxins TcdA and TcdB also neutralized the cytopathic effect, suggesting that tolevamer is specifically neutralizing these toxins and that the binary toxin (whose genes are carried by the BI/027 strains) is not a significant source of cytopathology against tissue culture cells in vitro.

  18. Toxins produced in cyanobacterial water blooms ? toxicity and risks

    OpenAIRE

    Bl?ha, Lud?k; Babica, Pavel; Mar??lek, Blahoslav

    2009-01-01

    Cyanobacterial blooms in freshwaters represent a major ecological and human health problem worldwide. This paper briefly summarizes information on major cyanobacterial toxins (hepatotoxins, neurotoxins etc.) with special attention to microcystins-cyclic heptapeptides with high acute and chronic toxicities. Besides discussion of human health risks, microcystin ecotoxicology and consequent ecological risks are also highlighted. Although significant research attention has been paid to microcysti...

  19. Tetrodotoxin-Producing Bacteria: Detection, Distribution and Migration of the Toxin in Aquatic Systems

    Directory of Open Access Journals (Sweden)

    Timur Yu. Magarlamov

    2017-05-01

    Full Text Available This review is devoted to the marine bacterial producers of tetrodotoxin (TTX, a potent non-protein neuroparalytic toxin. In addition to the issues of the ecology and distribution of TTX-producing bacteria, this review examines issues relating to toxin migration from bacteria to TTX-bearing animals. It is shown that the mechanism of TTX extraction from toxin-producing bacteria to the environment occur through cell death, passive/active toxin excretion, or spore germination of spore-forming bacteria. Data on TTX microdistribution in toxic organs of TTX-bearing animals indicate toxin migration from the digestive system to target organs through the transport system of the organism. The role of symbiotic microflora in animal toxicity is also discussed: despite low toxin production by bacterial strains in laboratory conditions, even minimal amounts of TTX produced by intestinal microflora of an animal can contribute to its toxicity. Special attention is paid to methods of TTX detection applicable to bacteria. Due to the complexity of toxin detection in TTX-producing bacteria, it is necessary to use several methods based on different methodological approaches. Issues crucial for further progress in detecting natural sources of TTX investigation are also considered.

  20. Toxins Produced by Valsa mali var. mali and Their Relationship with Pathogenicity

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    Caixia Wang

    2014-03-01

    Full Text Available Valsa mali var. mali (Vmm, the causal agent of apple tree canker disease, produces various toxic compounds, including protocatechuic acid, p-hydroxybenzoic acid, p-hydroxyacetophenone, 3-(p-hydroxyphenylpropanoic acid and phloroglucinol. Here, we examined the relationship between toxin production and the pathogenicity of Vmm strains and determined their bioactivities in several assays, for further elucidating the pathogenesis mechanisms of Vmm and for developing new procedures to control this disease. The toxins were quantified with the high performance liquid chromatography (HPLC method, and the results showed that the strain with attenuated virulence produced low levels of toxins with only three to four kinds of compounds being detectable. In contrast, higher amounts of toxins were produced by the more aggressive strain, and all five compounds were detected. This indicated a significant correlation between the pathogenicity of Vmm strains and their ability to produce toxins. However, this correlation only existed in planta, but not in vitro. During the infection of Vmm, protocatechuic acid was first detected at three days post inoculation (dpi, and the others at seven or 11 dpi. In addition, all compounds produced noticeable symptoms on host plants at concentrations of 2.5 to 40 mmol/L, with protocatechuic acid being the most effective compound, whereas 3-(p-hydroxyphenylpropanoic acid or p-hydroxybenzoic acid were the most active compounds on non-host plants.

  1. Proteolytic processing of the Cyt1Ab1 toxin produced by Bacillus thuringiensis subsp. medellin

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    Elizabeth Escobar

    2000-10-01

    Full Text Available Bacillus thuringiensis produces d-endotoxins that require proteolytic processing to become active. The activation of the B. thuringiensis subsp. medellin 28 kDa (Cyt1Ab1 cytolytic toxin by trypsin, chymotrypsin and gut extract from Culex quinquefasciatus larvae was analyzed. The Cyt1Ab1 toxin of B. thuringiensis subsp. medellin was processed by all proteases tested to fragments between 23 and 25 kDa, while processing of the Cyt1Aa1 toxin produce fragments between 22.5 and 24.5 kDa. The Cyt1Ab1 toxin was preferentially processed at the alkaline pH of 12. The in vitro proteolytic processing of the Cyt1Ab1 toxin by C. quinquefasciatus larvae midgut extract showed a 25 kDa fragment; a similar result was observed when the activation was performed in the in vivo experiments. The solubilized Cyt1Ab1 toxin and the protease resistant cores generated by in vitro processing showed hemolytic activity but not mosquitocidal activity. Amino terminal sequence of the C. quinquefasciatus gut extract resistant fragment indicated that the cutting site was located between Lys31 and Asp32, with a sequence DDPNEKNNHNS; while for the trypsin-resistant fragment the cutting site was determined between Leu29 and Arg30, and for the chymotrypsin-resistant fragment between Arg30 and Lys31.

  2. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Science.gov (United States)

    2011-11-23

    ... AGRICULTURE Food Safety and Inspection Service 9 CFR Parts 416, 417, and 430 [Docket No. FSIS-2010-0023] Shiga... disks or CD-ROMs, and hand- or courier-delivered items: Send to U.S. Department of Agriculture (USDA... Microbiology Laboratory Guidebook (MLG) 5B, ``Detection and Isolation of Non-O157 Shiga-Toxin Producing...

  3. Classification of shiga toxin-producing escherichia coli (STEC) serotypes with hyperspectral microscope imagery

    Science.gov (United States)

    Non-O157:H7 Shiga toxin-producing Escherichia coli (STEC) strains such as O26, O45, O103, O111, O121 and O145 are recognized as serious outbreak to cause human illness due to their toxicity. Since a conventional microbiological method for cell counting is laborious and time-consuming process, optica...

  4. Phylogeny and disease association of Shiga toxin-producing Escherichia coli O91

    NARCIS (Netherlands)

    Mellmann, Alexander; Fruth, Angelika; Friedrich, Alexander W; Wieler, Lothar H; Harmsen, Dag; Werber, Dirk; Middendorf, Barbara; Bielaszewska, Martina; Karch, Helge

    The diversity and relatedness of 100 Shiga toxin-producing Escherichia coli O91 isolates from different patients were examined by multilocus sequence typing. We identified 10 specific sequence types (ST) and 4 distinct clonal groups. ST442 was significantly associated with hemolytic uremic syndrome.

  5. Emetic toxin-producing strains of Bacillus cereus show distinct characteristics within the Bacillus cereus group.

    NARCIS (Netherlands)

    Carlin, Frédéric; Fricker, Martina; Pielaat, Annemarie; Heisterkamp, Simon; Shaheen, Ranad; Salonen, Mirja Salkinoja; Svensson, Birgitta; Nguyen-the, Christophe; Ehling-Schulz, Monika

    2006-01-01

    One hundred representative strains of Bacillus cereus were selected from a total collection of 372 B. cereus strains using two typing methods (RAPD and FT-IR) to investigate if emetic toxin-producing hazardous B. cereus strains possess characteristic growth and heat resistance profiles. The strains

  6. Shiga toxin-producing E. coli and ruminant diets: A match made in heaven?

    Science.gov (United States)

    Shiga-toxin producing E. coli (STEC) are also known as enterohemorrhagic E. coli (EHEC), which are pathogenic bacteria that can cause serious illnesses in humans who consume contaminated foods or water. This pathogen is commonly associated with cattle as it can survive within the intestinal tract a...

  7. Dynamical analysis of a toxin-producing phytoplankton-zooplankton model with refuge.

    Science.gov (United States)

    Li, Juan; Song, Yongzhong; Wan, Hui

    2017-04-01

    To study the impacts of toxin produced by phytoplankton and refuges provided for phytoplankton on phytoplankton-zooplankton interactions in lakes, we establish a simple phytoplankton-zooplankton system with Holling type II response function. The existence and stability of positive equilibria are discussed. Bifurcation analyses are given by using normal form theory which reveals reasonably the mechanisms and nonlinear dynamics of the effects of toxin and refuges, including Hopf bifurcation, Bogdanov-Takens bifurcation of co-dimension 2 and 3. Numerical simulations are carried out to intuitively support our analytical results and help to explain the observed biological behaviors. Our findings finally show that both phytoplankton refuge and toxin have a significant impact on the occurring and terminating of algal blooms in freshwater lakes.

  8. Active Shiga-like toxin produced by some Aeromonas spp., isolated in Mexico City

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    Ingrid Palma-Martínez

    2016-09-01

    Full Text Available Shiga-like toxins (Stx represent a group of bacterial toxins involved in human and animal diseases. Stx is produced by enterohemorrhagic Escherichia coli, Shigella dysenteriae type 1, Citrobacter freundii and Aeromonas spp. Stx is an important cause of bloody diarrhea and hemolytic uremic syndrome (HUS. The aim of this study was to identify the stx1/stx2 genes in clinical strains and in outer membrane vesicles (OMVs of Aeromonas spp., 66 strains were isolated from children who live in Mexico City and Shiga-like toxins effects were evaluated on Vero cell cultures.The capacity to express active, Stx1 and Stx2 toxins was determined on Vero cell cultures and the concentration of Shiga-like toxins was evaluated by lethal dose to 50% (LD50 assays, observing inhibition of damaged cells by specific monoclonal antibodies. The results obtained in this study support the hypothesis that the stx gene is another putative virulence factor of Aeromonas, and since this gene can be transferred horizontally through OMVs this genus should be included as a possible causal agents of gastroenteritis and it should be reported as part of standard health surveillance procedures.Furthermore, these results indicate that Aeromonas genus might be a potential causative agent of HUS.

  9. Biofilm-Forming Abilities of Shiga Toxin-Producing Escherichia coli Isolates Associated with Human Infections

    Science.gov (United States)

    Vogeleer, Philippe; Tremblay, Yannick D. N.; Jubelin, Grégory; Jacques, Mario

    2015-01-01

    Forming biofilms may be a survival strategy of Shiga toxin-producing Escherichia coli to enable it to persist in the environment and the food industry. Here, we evaluate and characterize the biofilm-forming ability of 39 isolates of Shiga toxin-producing Escherichia coli isolates recovered from human infection and belonging to seropathotypes A, B, or C. The presence and/or production of biofilm factors such as curli, cellulose, autotransporter, and fimbriae were investigated. The polymeric matrix of these biofilms was analyzed by confocal microscopy and by enzymatic digestion. Cell viability and matrix integrity were examined after sanitizer treatments. Isolates of the seropathotype A (O157:H7 and O157:NM), which have the highest relative incidence of human infection, had a greater ability to form biofilms than isolates of seropathotype B or C. Seropathotype A isolates were unique in their ability to produce cellulose and poly-N-acetylglucosamine. The integrity of the biofilms was dependent on proteins. Two autotransporter genes, ehaB and espP, and two fimbrial genes, z1538 and lpf2, were identified as potential genetic determinants for biofilm formation. Interestingly, the ability of several isolates from seropathotype A to form biofilms was associated with their ability to agglutinate yeast in a mannose-independent manner. We consider this an unidentified biofilm-associated factor produced by those isolates. Treatment with sanitizers reduced the viability of Shiga toxin-producing Escherichia coli but did not completely remove the biofilm matrix. Overall, our data indicate that biofilm formation could contribute to the persistence of Shiga toxin-producing Escherichia coli and specifically seropathotype A isolates in the environment. PMID:26712549

  10. Shiga Toxin-Producing Escherichia coli O157, England and Wales, 1983-2012.

    Science.gov (United States)

    Adams, Natalie L; Byrne, Lisa; Smith, Geraldine A; Elson, Richard; Harris, John P; Salmon, Roland; Smith, Robert; O'Brien, Sarah J; Adak, Goutam K; Jenkins, Claire

    2016-04-01

    We evaluated clinical Shiga toxin-producing Escherichia coli O157 infections in England and Wales during 1983-2012 to describe changes in microbiological and surveillance methods. A strain replacement event was captured; phage type (PT) 2 decreased to account for just 3% of cases by 2012, whereas PT8 and PT21/28 strains concurrently emerged, constituting almost two thirds of cases by 2012. Despite interventions to control and reduce transmission, incidence remained constant. However, sources of infection changed over time; outbreaks caused by contaminated meat and milk declined, suggesting that interventions aimed at reducing meat cross-contamination were effective. Petting farm and school and nursery outbreaks increased, suggesting the emergence of other modes of transmission and potentially contributing to the sustained incidence over time. Studies assessing interventions and consideration of policies and guidance should be undertaken to reduce Shiga toxin-producing E. coli O157 infections in England and Wales in line with the latest epidemiologic findings.

  11. Coprinus comatus damages nematode cuticles mechanically with spiny balls and produces potent toxins to immobilize nematodes.

    Science.gov (United States)

    Luo, Hong; Liu, Yajun; Fang, Lin; Li, Xuan; Tang, Ninghua; Zhang, Keqin

    2007-06-01

    We reported recently a unique fungal structure, called the spiny ball, on the vegetative hyphae of Coprinus comatus (O. F. Müll.:Fr.) Pers. Although some observations regarding the role of this structure were presented, its function remained largely unknown. In this study, we showed that purified (isolated and washed) spiny balls could immobilize and kill the free-living nematode Panagrellus redivivus Goodey highly efficiently. Scanning electron microscopy studies illustrated that the spiny structure damaged the nematode cuticle, suggesting the presence of a mechanical force during the process of nematode immobilization. Severe injuries on nematode cuticles caused the leakage of inner materials of the nematodes. When these structures were ground in liquid nitrogen, their killing efficacy against nematodes was lost, indicating that the shape and the complete structure of the spiny balls are indispensable for their function. However, extraction with organic solvents never lowered their activity against P. redivivus, and the extracts showed no obvious effect on the nematode. We also investigated whether C. comatus was able to produce toxins which would aid in the immobilization of nematodes. In total, we identified seven toxins from C. comatus that showed activity to immobilize the nematodes P. redivivus and Meloidogyne incognita (Kofoid et White) Chitwood. The chemical structures of these toxins were identified with nuclear magnetic resonance, mass spectrometry, infrared, and UV spectrum analysis. Two compounds were found to be novel. The toxins found in C. comatus are O-containing heterocyclic compounds.

  12. Coprinus comatus Damages Nematode Cuticles Mechanically with Spiny Balls and Produces Potent Toxins To Immobilize Nematodes▿

    Science.gov (United States)

    Luo, Hong; Liu, Yajun; Fang, Lin; Li, Xuan; Tang, Ninghua; Zhang, Keqin

    2007-01-01

    We reported recently a unique fungal structure, called the spiny ball, on the vegetative hyphae of Coprinus comatus (O. F. Müll.:Fr.) Pers. Although some observations regarding the role of this structure were presented, its function remained largely unknown. In this study, we showed that purified (isolated and washed) spiny balls could immobilize and kill the free-living nematode Panagrellus redivivus Goodey highly efficiently. Scanning electron microscopy studies illustrated that the spiny structure damaged the nematode cuticle, suggesting the presence of a mechanical force during the process of nematode immobilization. Severe injuries on nematode cuticles caused the leakage of inner materials of the nematodes. When these structures were ground in liquid nitrogen, their killing efficacy against nematodes was lost, indicating that the shape and the complete structure of the spiny balls are indispensable for their function. However, extraction with organic solvents never lowered their activity against P. redivivus, and the extracts showed no obvious effect on the nematode. We also investigated whether C. comatus was able to produce toxins which would aid in the immobilization of nematodes. In total, we identified seven toxins from C. comatus that showed activity to immobilize the nematodes P. redivivus and Meloidogyne incognita (Kofoid et White) Chitwood. The chemical structures of these toxins were identified with nuclear magnetic resonance, mass spectrometry, infrared, and UV spectrum analysis. Two compounds were found to be novel. The toxins found in C. comatus are O-containing heterocyclic compounds. PMID:17449690

  13. Isolation of Shiga toxin-producing Escherichia coli from raw milk in Kermanshah, Iran.

    Science.gov (United States)

    Mohammadi, Pantea; Abiri, Ramin; Rezaei, Mansour; Salmanzadeh-Ahrabi, Siavosh

    2013-09-01

    Infectious diarrhoeal diseases are great problem throughout the world and are responsible for considerable morbidity and mortality. Shiga toxin-producing Escherichia coli (STEC) is a major cause of gastroenteritis that may be complicated by hemorrhagic colitis (HC) or the hemolytic uremic syndrome (HUS), which is the main cause of acute renal failure in children. Food-borne outbreaks associated with Shiga toxin-producing Escherichia coli have been well documented worldwide. The aim of this study was to investigate the prevalence of Shiga toxin-producing Escherichia coli (STEC) strains in raw milk samples. Raw milk samples collected from various cow farms in Kermanshah, Iran during June - September 2009 were investigated for STEC using PCR targeting stx1 and stx2 and then eaeA. Of 206 samples, 36 (17.47%) were contaminated with STEC. STEC isolates harbored 56.41% and 43.59% stx 2 and stx 1 gene respectively. In antibiotic resistance test, all strains were sensitive to ceftazidime, cefepime, gentamicin, imipenem and ciprofloxacin. 23.08% of isolates were resistat to tetracycline, and 38.5% of them showed intermediate sensitvity to cephalothin. The high presence of STEC in raw milk confirms the important role of raw milk as putative vehicle of infection to human. Moreover, this study suggests that the development of antibiotic resistant STEC must be a major concern in Iran and more studies are needed to identify the prevalence of STEC in other food samples.

  14. Differentiation and distribution of three types of exfoliative toxin produced by Staphylococcus hyicus from pigs with exudative epidermitis

    DEFF Research Database (Denmark)

    Andresen, Lars Ole

    1998-01-01

    were antigenically distinct. The three toxins were designated ExhA, ExhB and ExhC. From 60 diseased pigs, each representing an outbreak of exudative epidermitis, a total of 584 isolates of S. hl icus were phage typed and tested for production of exfoliative toxin. ExhA-, ExhB- and ExhC-producing S...

  15. Characteristics of Shiga Toxin-Producing Escherichia coli O157 in Slaughtered Reindeer from Northern Finland.

    Science.gov (United States)

    Zweifel, Claudio; Fierz, Lisa; Cernela, Nicole; Laaksonen, Sauli; Fredriksson-Ahomaa, Maria; Stephan, Roger

    2017-03-01

    Fecal samples collected from 470 slaughtered reindeer 6 to 7 months of age were screened by real-time PCR (after enrichment) for Shiga toxin genes (stx) and then for Escherichia coli serogroup O157. Shiga toxin genes were found frequently (>30% of samples), and serogroup O157 was detected in 20% of the stx-positive samples. From these samples, a total of 25 E. coli O157:H - isolates (nonmotile but PCR positive for fliC H7 ) were obtained. Twenty-four of these E. coli O157:H - isolates did not ferment sorbitol and originated from one geographic area. These 24 isolates belonged to the multilocus sequence type 11, typical for Shiga toxin-producing E. coli (STEC) O157:H7 and O157:H - , and harbored genes stx 1a , stx 2c , eae, and hlyA; the stx 2c subtype has been associated with high virulence. In contrast, one E. coli O157:H - isolate (multilocus sequence type 11) did ferment sorbitol, lacked Shiga toxin genes, but was positive for eae, hlyA, and sfpA. This isolate closely resembled an STEC that has lost its Shiga toxin genes. Additional examination revealed that reindeer can be colonized by various other STEC isolates; 21 non-O157 STEC isolates belonged to four multilocus sequence types, harbored stx 1a (8 isolates) or stx 2b (13 isolates), and in the stx 2b -positive isolates the recently described new allelic variants (subAB2-2 and subAB2-3) for subtilase cytotoxin were identified. Hence, slaughtered semidomesticated Finnish reindeer might constitute a little known reservoir for STEC O157:H7/H - and other serogroups, and the risk of direct or indirect transmission of these pathogens from reindeer to humans and domestic livestock must not be overlooked.

  16. Control of Resistant Pink Bollworm (Pectinophora gossypiella) by Transgenic Cotton That Produces Bacillus thuringiensis Toxin Cry2Ab

    OpenAIRE

    Tabashnik, Bruce E.; Dennehy, Timothy J.; Sims, Maria A.; Larkin, Karen; Head, Graham P.; Moar, William J.; Carrière, Yves

    2002-01-01

    Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a major cotton pest. To counter potential problems with resistance, second-generation transgenic cotton...

  17. Genotypic characterization and biofilm formation of Shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Picozzi, Claudia; Antoniani, Davide; Vigentini, Ileana; Foschino, Roberto; Kneifel, Wolfgang

    2017-01-01

    Shiga toxin-producing Escherichia coli (STEC) are recognized as one of the most dangerous foodborne pathogens. The production of Shiga toxins together with intimin protein is among the main virulence factors. However, the ability to form biofilm can protect bacteria against environmental factors (i.e. desiccation, exposure to UV rays, predation, etc.) and sanitization procedures (cleaning, rinsing, chlorination), increasing their survival on food products and in manufacturing plants. Forty-five isolates collected from food and fecal samples were genotyped by pulsed field gel electrophoresis analysis with XbaI restriction enzyme and investigated by searching for toxins (stx1, stx2) and intimin (eae) genes and serogroup (O157, O26, O145, O111, O103 and O104). Afterward, the ability to develop biofilm in microtiter assay and the production of adhesive curli fimbriae and cellulose on agar plates were tested. Our study demonstrated that biofilm formation has a great variability among STEC strains and cannot be related to a specific pulsotype nor even to serogroup or presence of virulence genes. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. The effects of the ciliate Paramecium cf. caudatum Ehrenberg on toxin producing Cylindrospermopsis isolated from the Fitzroy River, Australia.

    Science.gov (United States)

    Fabbro, L; Baker, M; Dilvenvoorden, L; Pegg, G; Shiel, R

    2001-01-01

    The large ciliate Paramecium cf. caudatum Ehrenberg was found to be a successful grazer of toxin producing Cylindrospermopsis in the laboratory. The feeding rate increased with increasing cell concentration to 1367 cell animal hr-1 at 4.1 x 10(5) cells mL-1 but declined slightly at cell concentrations greater than this. Preliminary studies on the effects of this grazing on toxin concentrations in cultures of both straight and coiled forms of Cylindrospermopsis resulted in the production of different amounts of the toxin cylindrospermopsin in the different isolates. Differences in toxin production were also found between cultured and field populations from the lower Fitzroy River indicating that toxin production may be influenced by a suite of genetic and environmental factors. The proven ability of this ciliate to graze toxic Cylindrospermopsis provides some insight into interactions that may be able to control some toxic blooms in semiarid Australian conditions.

  19. Occurrence of multidrug resistance shiga-toxin producing Escherichia coli from milk and milk products

    OpenAIRE

    Javeed Ahmad Sheikh; Mohd. Rashid; Majueeb U Rehman; M. A. Bhat

    2013-01-01

    Aim: The aim of this study was to assess the hygienic quality of milk and milk products in respect of shiga toxin producingEscherichia coli (STEC).Materials and Methods: 205 samples of raw milk and milk products were processed for isolation of E. coli. The isolates werescreened by mPCR for detection of virulence gene. 52 E. coli isolates were tested against 15 commonly used antibiotics in thefield.Results: Of the 205 samples of milk and milk products 52 (25.36%) were positive for E. coli. Out...

  20. Expansion of Shiga Toxin-Producing Escherichia coli by Use of Bovine Antibiotic Growth Promoters.

    Science.gov (United States)

    Kim, Jong-Chul; Chui, Linda; Wang, Yang; Shen, Jianzhong; Jeon, Byeonghwa

    2016-05-01

    Antibiotics are routinely used in food-producing animals to promote growth and prevent infectious diseases. We investigated the effects of bovine antibiotic growth promoters (bAGPs) on the propagation and spread of Shiga toxin (Stx)-encoding phages in Escherichia coli. Co-culture of E. coli O157:H7 and other E. coli isolated from cattle in the presence of sublethal concentrations of bAGPs significantly increased the emergence of non-O157, Stx-producing E. coli by triggering the SOS response system in E. coli O157:H7. The most substantial mediation of Stx phage transmission was induced by oxytetracyline and chlortetracycline, which are commonly used in agriculture. bAGPs may therefore contribute to the expansion of pathogenic Stx-producing E. coli.

  1. Detection of Shiga-like toxin producing Escherichia coli from raw milk cheeses produced in Wallonia [Belgium].

    Directory of Open Access Journals (Sweden)

    El-Lioui M.

    1999-01-01

    Full Text Available Shiga-like toxin Escherichia coli (STEC implicated in aqueous diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome, has become a serious health problem in various countries. In Belgium, all cases are sporadic and no outbreak has been detected so far. Cattle are thought to be a reservoir for E. coli O157:H7, and many foodborne diseases have been associated with the consumption of minced beef, beefburgers and raw milk. Recently, foodborne outbreaks were concerned with different unusual foods such as acidic products. Although some data suggest that STEC are not prevalent within dairy products, the aim of this work was to assess the prevalence of E. coli O157 and non-O157 STEC in raw milk cheeses produced in the southern part of Belgium (Wallonia. For this purpose, 153 frozen samples of soft and semi-soft cheeses made with raw cow, ewe and goat milk were analysed for the presence of E. coli O157 and STEC. By using a dynabeads immunomagnetic separation technique (Dynabeads anti-E. coli O157, Dynal followed by streaking onto sorbitol MacConckey agar, no sample was found contaminated by E. coli O157 serotype. By using polymerase chain reaction achieved from a loopful of confluent bacterial material growing onto MacConckey agar, the use of consensus primers detected stx genes in 11.1/ of the samples but Shiga-like toxin producing strains could be isolated only in five of them (3.3/. The isolation rate seems to be optimum for samples with a thermotolerant coliform count arround or below 102 cfu per g. The five Shiga-like toxin isolates were identified as belonging to the species Hafnia alvei or Enterobacter amnigenius without any accessory virulence factors needed to cause illness. Nevertheless, because of the ability of STEC to survive adverse conditions and the possibility for commensal non-pathogenic enteric bacteria to become pathogenic, raw milk cheeses are to be considered at risk for foodborne STEC contamination.

  2. Detection of Shiga toxin-producing Escherichia coli in meat marketed in Casablanca (Morocco).

    Science.gov (United States)

    Badri, S; Fassouane, A; Filliol, I; Hassar, M; Cohen, N

    2011-03-01

    The contamination of meat and meat products with Shiga toxin-producing O157:H7 and non-O157 Escherichia coli (STEC), obtained from markets in Casablanca, Morocco, was investigated. A total of 460 meat and meat products were sampled between March 2004 and July 2006 analysed and 176 strains of E. coli were isolated from these samples. The presence of the stx1, stx2, eae and ehxA genes, recognized as major virulence factors of STEC, was tested in E. coli isolates by polymerase chain reaction (PCR). STEC was detected in 4 (0.9%) samples. The result of serotyping by molecular method showed that two of these STEC isolates corresponded to the serotype O157:H7. The others Shiga toxin-producing E. coli non-O157 corresponded to O6:H21 and O76:H19. The presence of O157:H7 and non-O157 STEC in meat and meat products marketed in Casablanca, Morocco, emphasizes the importance of implementing the Hazard Analysis and Critical Control Point (HACCP) system, as well as the need for implementing, evaluating, and validating antimicrobial interventions to reduce the presence of potential pathogenic microorganisms.

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

    Science.gov (United States)

    Sandhu, K S; Gyles, C L

    2002-04-01

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

  4. Development and characterization of recombinant antibody fragments that recognize and neutralize in vitro Stx2 toxin from Shiga toxin-producing Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Daniela Luz

    Full Text Available Stx toxin is a member of the AB5 family of bacterial toxins: the active A subunit has N-glycosidase activity against 28S rRNA, resulting in inhibition of protein synthesis in eukaryotic cells, and the pentamer ligand B subunits (StxB bind to globotria(tetraosylceramide receptors (Gb3/Gb4 on the cell membrane. Shiga toxin-producing Escherichia coli strains (STEC may produce Stx1 and/or Stx2 and variants. Strains carrying Stx2 are considered more virulent and related to the majority of outbreaks, besides being usually associated with hemolytic uremic syndrome in humans. The development of tools for the detection and/or neutralization of these toxins is a turning point for early diagnosis and therapeutics. Antibodies are an excellent paradigm for the design of high-affinity, protein-based binding reagents used for these purposes.In this work, we developed two recombinant antibodies; scFv fragments from mouse hybridomas and Fab fragments by phage display technology using a human synthetic antibody library. Both fragments showed high binding affinity to Stx2, and they were able to bind specifically to the GKIEFSKYNEDDTF region of the Stx2 B subunit and to neutralize in vitro the cytotoxicity of the toxin up to 80%. Furthermore, the scFv fragments showed 79% sensitivity and 100% specificity in detecting STEC strains by ELISA.In this work, we developed and characterized two recombinant antibodies against Stx2, as promising tools to be used in diagnosis or therapeutic approaches against STEC, and for the first time, we showed a human monovalent molecule, produced in bacteria, able to neutralize the cytotoxicity of Stx2 in vitro.

  5. Heat stability of reconstituted, protein-standardized skim milk powders.

    Science.gov (United States)

    Sikand, V; Tong, P S; Walker, J

    2010-12-01

    We determined the effects of standardization material, protein content, and pH on the heat stability of reconstituted milk made from low-heat (LH) and medium-heat (MH) nonfat dry milk (NDM). Low-heat and MH NDM were standardized downward from 35.5% to 34, 32, and 30% protein by adding either edible lactose powder (ELP) or permeate powder (PP) from skim milk ultrafiltration. These powders were called standardized skim milk powders (SSMP). The LH and MH NDM and SSMP were reconstituted to 9% total solids. Furthermore, subsamples of reconstituted NDM and SSMP samples were set aside to measure heat stability at native (unadjusted) pH, and the rest were adjusted to pH 6.3 to 7.0. Heat stability is defined as heat coagulation time at 140°C of the reconstituted LH or MH NDM and SSMP samples. The entire experiment was replicated 3 times at unadjusted pH values and 2 times at adjusted pH values. At an unadjusted pH, powder type, standardization material, and protein content influenced the heat stability of the samples. Heat stability for reconstituted LH NDM and SSMP was higher than reconstituted MH NDM and SSMP. Generally, decreased heat stability was observed in reconstituted LH or MH SSMP as protein content was decreased by standardization. However, adding ELP to MH SSMP did not significantly change its heat stability. When pH was adjusted to values between 6.3 and 7.0, powder type, standardization material, and pH had a significant effect on heat stability, whereas protein content did not. Maximum heat stability was noted at pH 6.7 for both reconstituted LH NDM and SSMP samples, and at pH 6.6 for both reconstituted MH NDM and SSMP samples. Furthermore, for samples with adjusted pH, higher heat stability was observed for reconstituted LH SSMP containing PP compared with reconstituted milk from LH SSMP containing ELP. However, no statistical difference was observed in the heat stability of reconstituted milk from MH NDM and MH SSMP samples. We conclude that powder type

  6. Proteome response of Tribolium castaneum larvae to Bacillus thuringiensis toxin producing strains.

    Directory of Open Access Journals (Sweden)

    Estefanía Contreras

    Full Text Available Susceptibility of Tribolium castaneum (Tc larvae was determined against spore-crystal mixtures of five coleopteran specific and one lepidopteran specific Bacillus thuringiensis Cry toxin producing strains and those containing the structurally unrelated Cry3Ba and Cry23Aa/Cry37Aa proteins were found toxic (LC(50 values 13.53 and 6.30 µg spore-crystal mixture/µL flour disc, respectively. Using iTRAQ combined with LC-MS/MS allowed the discovery of seven novel differentially expressed proteins in early response of Tc larvae to the two active spore-crystal mixtures. Proteins showing a statistically significant change in treated larvae compared to non-intoxicated larvae fell into two major categories; up-regulated proteins were involved in host defense (odorant binding protein C12, apolipophorin-III and chemosensory protein 18 and down-regulated proteins were linked to metabolic pathways affecting larval metabolism and development (pyruvate dehydrogenase Eα subunit, cuticular protein, ribosomal protein L13a and apolipoprotein LI-II. Among increased proteins, Odorant binding protein C12 showed the highest change, 4-fold increase in both toxin treatments. The protein displayed amino acid sequence and structural homology to Tenebrio molitor 12 kDa hemolymph protein b precursor, a non-olfactory odorant binding protein. Analysis of mRNA expression and mortality assays in Odorant binding protein C12 silenced larvae were consistent with a general immune defense function of non-olfactory odorant binding proteins. Regarding down-regulated proteins, at the transcriptional level, pyruvate dehydrogenase and cuticular genes were decreased in Tc larvae exposed to the Cry3Ba producing strain compared to the Cry23Aa/Cry37Aa producing strain, which may contribute to the developmental arrest that we observed with larvae fed the Cry3Ba producing strain. Results demonstrated a distinct host transcriptional regulation depending upon the Cry toxin treatment. Knowledge

  7. Proteome response of Tribolium castaneum larvae to Bacillus thuringiensis toxin producing strains.

    Science.gov (United States)

    Contreras, Estefanía; Rausell, Carolina; Real, M Dolores

    2013-01-01

    Susceptibility of Tribolium castaneum (Tc) larvae was determined against spore-crystal mixtures of five coleopteran specific and one lepidopteran specific Bacillus thuringiensis Cry toxin producing strains and those containing the structurally unrelated Cry3Ba and Cry23Aa/Cry37Aa proteins were found toxic (LC(50) values 13.53 and 6.30 µg spore-crystal mixture/µL flour disc, respectively). Using iTRAQ combined with LC-MS/MS allowed the discovery of seven novel differentially expressed proteins in early response of Tc larvae to the two active spore-crystal mixtures. Proteins showing a statistically significant change in treated larvae compared to non-intoxicated larvae fell into two major categories; up-regulated proteins were involved in host defense (odorant binding protein C12, apolipophorin-III and chemosensory protein 18) and down-regulated proteins were linked to metabolic pathways affecting larval metabolism and development (pyruvate dehydrogenase Eα subunit, cuticular protein, ribosomal protein L13a and apolipoprotein LI-II). Among increased proteins, Odorant binding protein C12 showed the highest change, 4-fold increase in both toxin treatments. The protein displayed amino acid sequence and structural homology to Tenebrio molitor 12 kDa hemolymph protein b precursor, a non-olfactory odorant binding protein. Analysis of mRNA expression and mortality assays in Odorant binding protein C12 silenced larvae were consistent with a general immune defense function of non-olfactory odorant binding proteins. Regarding down-regulated proteins, at the transcriptional level, pyruvate dehydrogenase and cuticular genes were decreased in Tc larvae exposed to the Cry3Ba producing strain compared to the Cry23Aa/Cry37Aa producing strain, which may contribute to the developmental arrest that we observed with larvae fed the Cry3Ba producing strain. Results demonstrated a distinct host transcriptional regulation depending upon the Cry toxin treatment. Knowledge on how insects

  8. Phylogeography of Cylindrospermopsin and Paralytic Shellfish Toxin-Producing Nostocales Cyanobacteria from Mediterranean Europe (Spain)

    Science.gov (United States)

    Cirés, Samuel; Wörmer, Lars; Ballot, Andreas; Agha, Ramsy; Wiedner, Claudia; Velázquez, David; Casero, María Cristina

    2014-01-01

    Planktonic Nostocales cyanobacteria represent a challenge for microbiological research because of the wide range of cyanotoxins that they synthesize and their invasive behavior, which is presumably enhanced by global warming. To gain insight into the phylogeography of potentially toxic Nostocales from Mediterranean Europe, 31 strains of Anabaena (Anabaena crassa, A. lemmermannii, A. mendotae, and A. planctonica), Aphanizomenon (Aphanizomenon gracile, A. ovalisporum), and Cylindrospermopsis raciborskii were isolated from 14 freshwater bodies in Spain and polyphasically analyzed for their phylogeography, cyanotoxin production, and the presence of cyanotoxin biosynthesis genes. The potent cytotoxin cylindrospermopsin (CYN) was produced by all 6 Aphanizomenon ovalisporum strains at high levels (5.7 to 9.1 μg CYN mg−1 [dry weight]) with low variation between strains (1.5 to 3.9-fold) and a marked extracellular release (19 to 41% dissolved CYN) during exponential growth. Paralytic shellfish poisoning (PSP) neurotoxins (saxitoxin, neosaxitoxin, and decarbamoylsaxitoxin) were detected in 2 Aphanizomenon gracile strains, both containing the sxtA gene. This gene was also amplified in non-PSP toxin-producing Aphanizomenon gracile and Aphanizomenon ovalisporum. Phylogenetic analyses supported the species identification and confirmed the high similarity of Spanish Anabaena and Aphanizomenon strains with other European strains. In contrast, Cylindrospermopsis raciborskii from Spain grouped together with American strains and was clearly separate from the rest of the European strains, raising questions about the current assumptions of the phylogeography and spreading routes of C. raciborskii. The present study confirms that the nostocalean genus Aphanizomenon is a major source of CYN and PSP toxins in Europe and demonstrates the presence of the sxtA gene in CYN-producing Aphanizomenon ovalisporum. PMID:24334673

  9. Comparative Genomic and Phylogenetic Analysis of a Shiga Toxin Producing Shigella sonnei (STSS Strain

    Directory of Open Access Journals (Sweden)

    Domonkos Sváb

    2017-05-01

    Full Text Available Shigella strains are important agents of bacillary dysentery, and in recent years Shigella sonnei has emerged as the leading cause of shigellosis in industrialized and rapidly developing countries. More recently, several S. sonnei and Shigella flexneri strains producing Shiga toxin (Stx have been reported from sporadic cases and from an outbreak in America. In the present study we aimed to shed light on the evolution of a recently identified Shiga toxin producing S. sonnei (STSS isolated in Europe. Here we report the first completely assembled whole genome sequence of a multidrug resistant (MDR Stx-producing S. sonnei (STSS clinical strain and reveal its phylogenetic relations. STSS 75/02 proved to be resistant to ampicillin, streptomycin, tetracycline, chloramphenicol, thrimetoprim, and sulfomethoxazol. The genome of STSS 75/02 contains a 4,891,717 nt chromosome and seven plasmids including the 214 kb invasion plasmid (pInv harboring type III secretion system genes and associated effectors. The chromosome harbors 23 prophage regions including the Stx1 converting prophage. The genome carries all virulence determinants necessary for an enteroinvasive lifestyle, as well as the Stx1 encoding gene cluster within an earlier described inducible converting prophage. In silico SNP genotyping of the assembled genome as well as 438 complete or draft S. sonnei genomes downloaded from NCBI GenBank revealed that S. sonnei 75/02 belongs to the more recently diverged global MDR lineage (IIIc. Targeted screening of 1131 next-generation sequencing projects taken from NCBI Short Read Archive of confirms that only a few S. sonnei isolates are Stx positive. Our results suggest that the acquisition of Stx phages could have occurred in different environments as independent events and that multiple horizontal transfers are responsible for the appearance of Stx phages in S. sonnei strains.

  10. Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

    NARCIS (Netherlands)

    Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J.; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; van Minh, Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E.

  11. Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

    NARCIS (Netherlands)

    Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J.; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Minh, Van Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    Background: Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an

  12. Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

    NARCIS (Netherlands)

    Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Van Minh, Pham; Wagenaar, Jaap A; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    BACKGROUND: Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an

  13. Current trends in detecting non-O157 Shiga toxin-producing Escherichia coli in food.

    Science.gov (United States)

    Wang, Fei; Yang, Qianru; Kase, Julie A; Meng, Jianghong; Clotilde, Laurie M; Lin, Andrew; Ge, Beilei

    2013-08-01

    Non-O157 Shiga toxin-producing Escherichia coli (non-O157 STEC) strains are increasingly recognized as important foodborne pathogens worldwide. Together with E. coli O157:H7, six additional STEC serogroups (O26, O45, O103, O111, O121, and O145) are now regulated as adulterants in certain raw beef products in the United States. However, effective detection and isolation of non-O157 STEC strains from food matrices remain challenging. In the past decade, great attention has been paid to developing rapid and reliable detection methods for STEC in general (targeting common virulence factors) and specific STEC serogroups in particular (targeting serogroup-specific traits). This review summarizes current trends in detecting non-O157 STEC in food, including culture, immunological, and molecular methods, as well as several novel technologies.

  14. Occurrence of multidrug resistance shiga-toxin producing Escherichia coli from milk and milk products

    Directory of Open Access Journals (Sweden)

    Javeed Ahmad Sheikh

    2013-10-01

    Full Text Available Aim: The aim of this study was to assess the hygienic quality of milk and milk products in respect of shiga toxin producingEscherichia coli (STEC.Materials and Methods: 205 samples of raw milk and milk products were processed for isolation of E. coli. The isolates werescreened by mPCR for detection of virulence gene. 52 E. coli isolates were tested against 15 commonly used antibiotics in thefield.Results: Of the 205 samples of milk and milk products 52 (25.36% were positive for E. coli. Out of which 4% samples werepositive for STEC from raw milk and 3.64% from milk products. Also, 25 of 52 (48% of E. coli isolates were multidrugresistance whereas 62.5% of STEC from milk and milk products were multidrug resistance.Conclusions: The milk and milk products production is of poor hygienic quality in and around Jammu region which needsimprovement.

  15. In Silico Signature Prediction Modeling in Cytolethal Distending Toxin-Producing Escherichia coli Strains.

    Science.gov (United States)

    Javadi, Maryam; Oloomi, Mana; Bouzari, Saeid

    2017-06-01

    In this study, cytolethal distending toxin (CDT) producer isolates genome were compared with genome of pathogenic and commensal Escherichia coli strains. Conserved genomic signatures among different types of CDT producer E. coli strains were assessed. It was shown that they could be used as biomarkers for research purposes and clinical diagnosis by polymerase chain reaction, or in vaccine development. cdt genes and several other genetic biomarkers were identified as signature sequences in CDT producer strains. The identified signatures include several individual phage proteins (holins, nucleases, and terminases, and transferases) and multiple members of different protein families (the lambda family, phage-integrase family, phage-tail tape protein family, putative membrane proteins, regulatory proteins, restriction-modification system proteins, tail fiber-assembly proteins, base plate-assembly proteins, and other prophage tail-related proteins). In this study, a sporadic phylogenic pattern was demonstrated in the CDT-producing strains. In conclusion, conserved signature proteins in a wide range of pathogenic bacterial strains can potentially be used in modern vaccine-design strategies.

  16. Virulence gene profiles of Shiga-toxin producing Escherichia coli isolates from retail raw meat in Iran

    OpenAIRE

    M. Panahee; H. Pourtaghi

    2017-01-01

    Shiga toxin-producing Escherichia coli (STEC) is recognised as toxin producing group of E. coli and one of the most significant foodborne pathogens worldwide. The aim of this study was to detect STEC and determine virulence gene profiles of these pathogens in different kinds of meat and prod-ucts in Iran. For this reason a total of 182 samples of minced beef, mutton, chicken meat, chicken feet and mechanically separated chicken meat were collected from retail markets for detection of STEC by ...

  17. Strain-Level Discrimination of Shiga Toxin-Producing Escherichia coli in Spinach Using Metagenomic Sequencing.

    Science.gov (United States)

    Leonard, Susan R; Mammel, Mark K; Lacher, David W; Elkins, Christopher A

    2016-01-01

    Consumption of fresh bagged spinach contaminated with Shiga toxin-producing Escherichia coli (STEC) has led to severe illness and death; however current culture-based methods to detect foodborne STEC are time consuming. Since not all STEC strains are considered pathogenic to humans, it is crucial to incorporate virulence characterization of STEC in the detection method. In this study, we assess the comprehensiveness of utilizing a shotgun metagenomics approach for detection and strain-level identification by spiking spinach with a variety of genomically disparate STEC strains at a low contamination level of 0.1 CFU/g. Molecular serotyping, virulence gene characterization, microbial community analysis, and E. coli core gene single nucleotide polymorphism (SNP) analysis were performed on metagenomic sequence data from enriched samples. It was determined from bacterial community analysis that E. coli, which was classified at the phylogroup level, was a major component of the population in most samples. However, in over half the samples, molecular serotyping revealed the presence of indigenous E. coli which also contributed to the percent abundance of E. coli. Despite the presence of additional E. coli strains, the serotype and virulence genes of the spiked STEC, including correct Shiga toxin subtype, were detected in 94% of the samples with a total number of reads per sample averaging 2.4 million. Variation in STEC abundance and/or detection was observed in replicate spiked samples, indicating an effect from the indigenous microbiota during enrichment. SNP analysis of the metagenomic data correctly placed the spiked STEC in a phylogeny of related strains in cases where the indigenous E. coli did not predominate in the enriched sample. Also, for these samples, our analysis demonstrates that strain-level phylogenetic resolution is possible using shotgun metagenomic data for determining the genomic relatedness of a contaminating STEC strain to other closely related E

  18. Shiga Toxin-Producing Serogroup O91 Escherichia coli Strains Isolated from Food and Environmental Samples.

    Science.gov (United States)

    Feng, Peter C H; Delannoy, Sabine; Lacher, David W; Bosilevac, Joseph M; Fach, Patrick; Beutin, Lothar

    2017-09-15

    Shiga toxin-producing Escherichia coli (STEC) strains of the O91:H21 serotype have caused severe infections, including hemolytic-uremic syndrome. Strains of the O91 serogroup have been isolated from food, animals, and the environment worldwide but are not well characterized. We used a microarray and other molecular assays to examine 49 serogroup O91 strains (environmental, food, and clinical strains) for their virulence potential and phylogenetic relationships. Most of the isolates were identified to be strains of the O91:H21 and O91:H14 serotypes, with a few O91:H10 strains and one O91:H9 strain being identified. None of the strains had the eae gene, which codes for the intimin adherence protein, and many did not have some of the genetic markers that are common in other STEC strains. The genetic profiles of the strains within each serotype were similar but differed greatly between strains of different serotypes. The genetic profiles of the O91:H21 strains that we tested were identical or nearly identical to those of the clinical O91:H21 strains that have caused severe diseases. Multilocus sequence typing and clustered regularly interspaced short palindromic repeat analyses showed that the O91:H21 strains clustered within the STEC 1 clonal group but the other O91 serotype strains were phylogenetically diverse. IMPORTANCE This study showed that food and environmental O91:H21 strains have similar genotypic profiles and Shiga toxin subtypes and are phylogenetically related to the O91:H21 strains that have caused hemolytic-uremic syndrome, suggesting that these strains may also have the potential to cause severe illness. Copyright © 2017 American Society for Microbiology.

  19. Serogroup-specific risk factors for Shiga toxin-producing Escherichia coli infection in Australia.

    Science.gov (United States)

    McPherson, Michelle; Lalor, Karin; Combs, Barry; Raupach, Jane; Stafford, Russell; Kirk, Martyn D

    2009-07-15

    Shiga toxin-producing Escherichia coli (STEC) is an important cause of foodborne illness. In Australia, risk factors for STEC infection have not been examined at a national level. We conducted a case-control study in 6 Australian jurisdictions from 2003 through 2007. A case patient was defined as a person from whom STEC was isolated or toxin production genes were detected in stool. Case patients were recruited from notifiable disease registers, and 3 control subjects frequency matched by age were selected from databases of controls. Using structured questionnaires, interviewers collected data on clinical illness, foods consumed, and exposures to potential environmental sources. We recruited 43 case patients infected with STEC serogroup O157, 71 case patients infected with non-O157 serogroups, and 304 control subjects. One patient infected with serogroup O157 and 7 infected with non-O157 serogroups developed hemolytic uremic syndrome. Compared with control subjects, case patients infected with STEC O157 were more likely to eat hamburgers, visit restaurants, have previously used antibiotics, or have family occupational exposure to red meat. Case patients infected with non-O157 STEC were more likely to eat sliced chicken meat or corned beef from a delicatessen, camp in the bush, eat catered meals, or have family occupational exposure to animals. Negative associations were observed for certain foods, particularly homegrown vegetables, fruits, or herbs. This study of risk factors for STEC infection by serogroup highlights risks associated with eating hamburgers and occupational handling of raw meat. To prevent infection, hamburgers must be cooked thoroughly, and people handling raw meat or who have close contact with animals must ensure adequate hygiene.

  20. Strain-Level Discrimination of Shiga Toxin-Producing Escherichia coli in Spinach Using Metagenomic Sequencing.

    Directory of Open Access Journals (Sweden)

    Susan R Leonard

    Full Text Available Consumption of fresh bagged spinach contaminated with Shiga toxin-producing Escherichia coli (STEC has led to severe illness and death; however current culture-based methods to detect foodborne STEC are time consuming. Since not all STEC strains are considered pathogenic to humans, it is crucial to incorporate virulence characterization of STEC in the detection method. In this study, we assess the comprehensiveness of utilizing a shotgun metagenomics approach for detection and strain-level identification by spiking spinach with a variety of genomically disparate STEC strains at a low contamination level of 0.1 CFU/g. Molecular serotyping, virulence gene characterization, microbial community analysis, and E. coli core gene single nucleotide polymorphism (SNP analysis were performed on metagenomic sequence data from enriched samples. It was determined from bacterial community analysis that E. coli, which was classified at the phylogroup level, was a major component of the population in most samples. However, in over half the samples, molecular serotyping revealed the presence of indigenous E. coli which also contributed to the percent abundance of E. coli. Despite the presence of additional E. coli strains, the serotype and virulence genes of the spiked STEC, including correct Shiga toxin subtype, were detected in 94% of the samples with a total number of reads per sample averaging 2.4 million. Variation in STEC abundance and/or detection was observed in replicate spiked samples, indicating an effect from the indigenous microbiota during enrichment. SNP analysis of the metagenomic data correctly placed the spiked STEC in a phylogeny of related strains in cases where the indigenous E. coli did not predominate in the enriched sample. Also, for these samples, our analysis demonstrates that strain-level phylogenetic resolution is possible using shotgun metagenomic data for determining the genomic relatedness of a contaminating STEC strain to other

  1. Detection of Shiga Toxin-Producing Escherichia coli from Nonhuman Sources and Strain Typing.

    Science.gov (United States)

    Beutin, Lothar; Fach, Patrick

    2014-06-01

    Shiga toxin-producing Escherichia coli (STEC) strains are commonly found in the intestine of ruminant species of wild and domestic animals. Excretion of STEC with animal feces results in a broad contamination of food and the environment. Humans get infected with STEC through ingestion of contaminated food, by contact with the environment, and from STEC-excreting animals and humans. STEC strains can behave as human pathogens, and some of them, called enterohemorrhagic E. coli (EHEC), may cause hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Because of the diversity of STEC types, detection strategies for STEC and EHEC are based on the identification of Shiga toxins or the underlying genes. Cultural enrichment of STEC from test samples is needed for identification, and different protocols were developed for this purpose. Multiplex real-time PCR protocols (ISO/CEN TS13136 and USDA/FSIS MLG5B.01) have been developed to specifically identify EHEC by targeting the LEE (locus of enterocyte effacement)-encoded eae gene and genes for EHEC-associated O groups. The employment of more genetic markers (nle and CRISPR) is a future challenge for better identification of EHEC from any kinds of samples. The isolation of STEC or EHEC from a sample is required for confirmation, and different cultivation protocols and media for this purpose have been developed. Most STEC strains present in food, animals, and the environment are eae negative, but some of these strains can cause HC and HUS in humans as well. Phenotypic assays and molecular tools for typing EHEC and STEC strains are used to detect and characterize human pathogenic strains among members of the STEC group.

  2. The prevalence of Shiga toxin-producing Escherichia coli in domestic animals and food in Serbia.

    Science.gov (United States)

    Cobeljić, M; Dimić, B; Opacić, D; Lepsanović, Z; Stojanović, V; Lazić, S

    2005-04-01

    Faecal samples of 2660 domestic animals from 116 farms and 956 samples of food were examined for the presence of Shiga toxin-producing Escherichia coli (STEC). STEC was recovered from 126 (15.3%) cattle, 135 (11.3%) pigs, 135 (66.8%) sheep, 31 (73.8%) goats, 4 (1%) chicken, and 15 (1.6%) food samples. Of all STEC isolates, 21.5, 25.8 and 15% produced enterohaemolysin, alpha-haemolysin, and aerobactin respectively, 1.6% displayed localized adherence (LA) to HEp-2 cells, 27.6% were sorbitol negative, and 30% were resistant to antibiotics. Only 14 (3.1%) of the STEC isolates belonged to human infection-associated serogroups (O26, O55, O111, O128 and 0157), designated as enterohaemorrhagic E. coil (EHEC). This study revealed that STEC are prevalent in domestic animals, and to a lesser extent in food of animal origin in Serbia, but the absence of a EHEC phenotypic profile (characteristic serogroup, LA, enterohaemolysin production) in most animal STEC strains may explain the low incidence of human STEC infection in this part of the world.

  3. Classification of non-O157 shiga toxin-producing escherichia coli(STEC) serotypes with hyperspectral microscope imaging

    Science.gov (United States)

    Non-O157 Shiga toxin-producing Escherichia coli (STEC) strains such as O26, O45, O103, O111, O121 and O145 are recognized as serious outbreak to cause human illness due to their toxicity. A conventional microbiological method for cell counting is laborious and needs long time for the results. Since ...

  4. Rapid detection of E. coli produced shiga-like toxins by lateral flow immunoassay in multiple food matrices

    Science.gov (United States)

    Shiga toxigenic E. coli (STEC) produce shiga-like toxins (Stx) that can cause human disease and death. The STEC serotype O157:H7 is a well-recognized foodborne contaminant and effective detection methods have been established. However, the emergence of non-O157 STEC strains has necessitated the deve...

  5. Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli

    NARCIS (Netherlands)

    Noguera, P.; Posthuma-Trumpie, G.A.; Tuil, van M.; Wal, van der F.J.; Boer, de A.; Moers, A.P.H.A.; Amerongen, van A.

    2011-01-01

    The use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay,

  6. Biofilm formation of non-O157 Shiga toxin-producing Escherichia coli (STEC) on equipment surfaces

    Science.gov (United States)

    Introduction: Shiga toxin-producing Escherichia coli (STEC) serotype O157:H7 has been the most commonly recognized STEC serotype responsible for foodborne outbreaks in the US. Numerous outbreaks associated with non-O157 serotypes have also been reported due to consumption of contaminated food. The ...

  7. Biotinylation of environmentally isolated Shiga toxin-producing Escherichia coli (STEC) – specific bacteriophages for biosensor and biocontrol applications

    Science.gov (United States)

    Like common bacteriophages, Shiga toxin-producing Escherichia coli (STEC) bacteriophages are viruses that recognize and bind to specific bacterial host (STEC) for propagation. They co-exist with STEC hosts, which cause epidemic food and waterborne illnesses, but may act as host populations limiting ...

  8. Simultaneous direct detection of Shiga-toxin producing Escherichia coli (STEC) strains by gold nanoparticle optical sensing

    Science.gov (United States)

    Shiga-toxin producing Escherichia coli (STEC) strains (“Big Six” – O26, O45, O103, O111, O121, O145, and O157) represent significant groups of pathogens responsible for foodborne diseases. The objective of this study was to develop a colorimetric optical sensing assay that can simultaneously detect ...

  9. Conditional function of autoaggregative protien cah and common cah mutations in Shiga toxin-producing Escherichia coli

    Science.gov (United States)

    Cah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Although cah is widespread in Shiga toxin-producing Escherichia coli (STEC), we detected mutations in cah at a frequency of 31.3% in this pathogen. In STEC O157:H7 super-shedder strain SS17, a large d...

  10. Mathematical modeling of growth of non-O157 Shiga Toxin-producing Escherichia coli in raw ground beef

    Science.gov (United States)

    The objective of this study was to investigate the growth of Shiga toxin-producing Escherichia coli (STEC, including serogroups O45, O103, O111, O121, and O145) in raw ground beef and to develop mathematical models to describe the bacterial growth under different temperature conditions. Three prima...

  11. Prevalence and characteristics of Shiga toxin-producing Escherichia coli in finishing pigs: implications on public health

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens, which can cause serious illnesses, including hemorrhagic colitis and hemolytic uremic syndrome. To examine if pigs are potential animal reservoirs for human STEC infections, we conducted a longitudinal cohort study in ...

  12. Isolation and characterization of bacteriophages as potential agents against Shiga toxinproducing Escherichia coli (STEC) strains

    Science.gov (United States)

    Shiga – toxin producing Escherichia coli (STEC) is a significant group of foodborne pathogens that can cause mild diarrhea to serious human illnesses. The gastrointestinal tracts of cattle and other ruminants are the primary reservoirs of STEC strains and may co-harbor bacteriophages as part of its ...

  13. Outbreak of Non-O157 Shiga Toxin-Producing Escherichia coli Infection from Consumption of Beef Sausage

    DEFF Research Database (Denmark)

    Ethelberg, S.; Smith, B.; Torpdahl, M.

    2009-01-01

    We describe an outbreak of Shiga toxin-producing Escherichia coli O26: H11 infection in 20 patients (median age, 2 years). The source of the infection was an organic fermented beef sausage. The source was discovered by using credit card information to obtain and compare customer transaction records...

  14. Alga-Produced Cholera Toxin-Pfs25 Fusion Proteins as Oral Vaccines

    Science.gov (United States)

    Gregory, James A.; Topol, Aaron B.; Doerner, David Z.

    2013-01-01

    Infectious diseases disproportionately affect indigent regions and are the greatest cause of childhood mortality in developing countries. Practical, low-cost vaccines for use in these countries are paramount to reducing disease burdens and concomitant poverty. Algae are a promising low-cost system for producing vaccines that can be orally delivered, thereby avoiding expensive purification and injectable delivery. We engineered the chloroplast of the eukaryotic alga Chlamydomonas reinhardtii to produce a chimeric protein consisting of the 25-kDa Plasmodium falciparum surface protein (Pfs25) fused to the β subunit of the cholera toxin (CtxB) to investigate an alga-based whole-cell oral vaccine. Pfs25 is a promising malaria transmission-blocking vaccine candidate that has been difficult to produce in traditional recombinant systems due to its structurally complex tandem repeats of epidermal growth factor-like domains. The noncatalytic CtxB domain of the cholera holotoxin assembles into a pentameric structure and acts as a mucosal adjuvant by binding GM1 ganglioside receptors on gut epithelial cells. We demonstrate that CtxB-Pfs25 accumulates as a soluble, properly folded and functional protein within algal chloroplasts, and it is stable in freeze-dried alga cells at ambient temperatures. In mice, oral vaccination using freeze-dried algae that produce CtxB-Pfs25 elicited CtxB-specific serum IgG antibodies and both CtxB- and Pfs25-specific secretory IgA antibodies. These data suggest that algae are a promising system for production and oral delivery of vaccine antigens, but as an orally delivered adjuvant, CtxB is best suited for eliciting secretory IgA antibodies for vaccine antigens against pathogens that invade mucosal surfaces using this strategy. PMID:23603678

  15. Association of toxin-producing Clostridium botulinum with the macroalga Cladophora in the Great Lakes

    Science.gov (United States)

    Chun, Chan Lan; Ochsner, Urs; Byappanahalli, Muruleedhara N.; Whitman, Richard L.; Tepp, William H.; Lin, Guangyun; Johnson, Eric A.; Peller, Julie; Sadowsky, Michael J.

    2013-01-01

    Avian botulism, a paralytic disease of birds, often occurs on a yearly cycle and is increasingly becoming more common in the Great Lakes. Outbreaks are caused by bird ingestion of neurotoxins produced by Clostridium botulinum, a spore-forming, gram-positive, anaerobe. The nuisance, macrophytic, green alga Cladophora (Chlorophyta; mostly Cladophora glomerata L.) is a potential habitat for the growth of C. botulinum. A high incidence of botulism in shoreline birds at Sleeping Bear Dunes National Lakeshore (SLBE) in Lake Michigan coincides with increasingly massive accumulations of Cladophora in nearshore waters. In this study, free-floating algal mats were collected from SLBE and other shorelines of the Great Lakes between June and October 2011. The abundance of C. botulinum in algal mats was quantified and the type of botulism neurotoxin (bont) genes associated with this organism were determined by using most-probable-number PCR (MPN-PCR) and five distinct bont gene-specific primers (A, B, C, E, and F). The MPN-PCR results showed that 16 of 22 (73%) algal mats from the SLBE and 23 of 31(74%) algal mats from other shorelines of the Great Lakes contained the bont type E (bont/E) gene. C. botulinum was present up to 15 000 MPN per gram dried algae based on gene copies of bont/E. In addition, genes for bont/A and bont/B, which are commonly associated with human diseases, were detected in a few algal samples. Moreover, C. botulinum was present as vegetative cells rather than as dormant spores in Cladophora mats. Mouse toxin assays done using supernatants from enrichment of Cladophora containing high densities of C. botulinum (>1000 MPN/g dried algae) showed that Cladophora-borne C. botulinum were toxin-producing species (BoNT/E). Our results indicate that Cladophora provides a habitat for C. botulinum, warranting additional studies to better understand the relationship between this bacterium and the alga, and how this interaction potentially contributes to botulism

  16. A shift in the dominant toxin-producing algal species in central California alters phycotoxins in food webs

    Science.gov (United States)

    Jester, R.; Lefebvre, K.; Langlois, G.; Vigilant, V.; Baugh, K.; Silver, M.W.

    2009-01-01

    In California, the toxic algal species of primary concern are the dinoflagellate Alexandrium catenella and members of the pennate diatom genus Pseudo-nitzschia, both producers of potent neurotoxins that are capable of sickening and killing marine life and humans. During the summer of 2004 in Monterey Bay, we observed a change in the taxonomic structure of the phytoplankton community-the typically diatom-dominated community shifted to a red tide, dinoflagellate-dominated community. Here we use a 6-year time series (2000-2006) to show how the abundance of the dominant harmful algal bloom (HAB) species in the Bay up to that point, Pseudo-nitzschia, significantly declined during the dinoflagellate-dominated interval, while two genera of toxic dinoflagellates, Alexandrium and Dinophysis, became the predominant toxin producers. This change represents a shift from a genus of toxin producers that typically dominates the community during a toxic bloom, to HAB taxa that are generally only minor components of the community in a toxic event. This change in the local HAB species was also reflected in the toxins present in higher trophic levels. Despite the small contribution of A. catenella to the overall phytoplankton community, the increase in the presence of this species in Monterey Bay was associated with an increase in the presence of paralytic shellfish poisoning (PSP) toxins in sentinel shellfish and clupeoid fish. This report provides the first evidence that PSP toxins are present in California's pelagic food web, as PSP toxins were detected in both northern anchovies (Engraulis mordax) and Pacific sardines (Sardinops sagax). Another interesting observation from our data is the co-occurrence of DA and PSP toxins in both planktivorous fish and sentinel shellfish. We also provide evidence, based on the statewide biotoxin monitoring program, that this increase in the frequency and abundance of PSP events related to A. catenella occurred not just in Monterey Bay, but also

  17. Thermal inactivation of Escherichia coli 0157:H7 (ECOH) and non-0157 Shiga toxin-producing E.coli (STEC)in mechanically tenderized veal

    Science.gov (United States)

    We quantified thermal destruction of Shiga toxin-producing Escherichia coli O157:H7 (ECOH) and Shiga toxin-producing non-O157 E. coli (STEC) cells within mechanically tenderized veal cutlets following cooking on an electric skillet. For each of five trials, flattened veal cutlets (ca. 71.6 g; ca. 1/...

  18. Veal Calves Produce Less Antibodies against C. Perfringens Alpha Toxin Compared to Beef Calves

    Directory of Open Access Journals (Sweden)

    Bonnie R. Valgaeren

    2015-07-01

    Full Text Available Enterotoxaemia is a disease with a high associated mortality rate, affecting beef and veal calves worldwide, caused by C. perfringens alpha toxin and perfringolysin. A longitudinal study was conducted to determine the dynamics of antibodies against these toxins in 528 calves on 4 beef and 15 veal farms. The second study aimed to determine the effect of solid feed intake on the production of antibodies against alpha toxin and perfringolysin. The control group only received milk replacer, whereas in the test group solid feed was provided. Maternal antibodies for alpha toxin were present in 45% of the veal calves and 66% of the beef calves. In beef calves a fluent transition from maternal to active immunity was observed for alpha toxin, whereas almost no veal calves developed active immunity. Perfringolysin antibodies significantly declined both in veal and beef calves. In the second study all calves were seropositive for alpha toxin throughout the experiment and solid feed intake did not alter the dynamics of alpha and perfringolysin antibodies. In conclusion, the present study showed that veal calves on a traditional milk replacer diet had significantly lower alpha toxin antibodies compared to beef calves in the risk period for enterotoxaemia, whereas no differences were noticed for perfringolysin.

  19. Recombinant GDNF: Tetanus toxin fragment C fusion protein produced from insect cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianhong; Chian, Ru-Ju; Ay, Ilknur; Celia, Samuel A.; Kashi, Brenda B.; Tamrazian, Eric; Matthews, Jonathan C. [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Remington, Mary P. [Research Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201 (United States); Pepinsky, R. Blake [BiogenIdec, Inc., 14 Cambridge Center, Cambridge, MA 02142 (United States); Fishman, Paul S. [Research Service, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201 (United States); Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Brown, Robert H. [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States); Francis, Jonathan W., E-mail: jwfrancisby@gmail.com [Cecil B. Day Laboratory for Neuromuscular Research, Department of Neurology, Massachusetts General Hospital, Charlestown, MA 02129 (United States)

    2009-07-31

    Glial cell line-derived neurotrophic factor (GDNF) has potent survival-promoting effects on CNS motor neurons in experimental animals. Its therapeutic efficacy in humans, however, may have been limited by poor bioavailability to the brain and spinal cord. With a view toward improving delivery of GDNF to CNS motor neurons in vivo, we generated a recombinant fusion protein comprised of rat GDNF linked to the non-toxic, neuron-binding fragment of tetanus toxin. Recombinant GDNF:TTC produced from insect cells was a soluble homodimer like wild-type GDNF and was bi-functional with respect to GDNF and TTC activity. Like recombinant rat GDNF, the fusion protein increased levels of immunoreactive phosphoAkt in treated NB41A3-hGFR{alpha}-1 neuroblastoma cells. Like TTC, GDNF:TTC bound to immobilized ganglioside GT1b in vitro with high affinity and selectivity. These results support further testing of recombinant GDNF:TTC as a non-viral vector to improve delivery of GDNF to brain and spinal cord in vivo.

  20. Prevention of secondary household transmission during Shiga toxin-producing Escherichia coli outbreaks.

    Science.gov (United States)

    Tokuda, K; Yahata, Y; Sunagawa, T

    2016-10-01

    Prevention of secondary household transmission of Shiga toxin-producing Escherichia coli (STEC) is important in outbreak settings. We examined factors contributing to secondary household transmission during STEC outbreaks in daycare centres in Japan. Suspected STEC outbreaks in daycare centres were identified by the National Epidemiological Surveillance of Infectious Diseases. Questionnaires were sent to local health centres that responded to outbreaks. Secondary household transmission rates were calculated, and factors affecting secondary household transmission rate were analysed by multilevel analysis. The secondary household transmission rates in 16 outbreaks ranged from 0% to 34·4% (median 4·4%). The highest rate (23·0%) was observed in siblings aged 6-9 years, and the infection rate was significantly higher for mothers than for fathers and grandparents (P families of children in daycare centres (at initial response), STEC type and lag time (days) between onset and providing information. Early response and hygiene education by visiting local health centre staff may be effective measures to prevent secondary household transmission in STEC outbreaks. Hygiene education should be emphasized for children aged 6-9 years, as well as for younger children.

  1. Intestinal organoids model human responses to infection by commensal and Shiga toxin producing Escherichia coli.

    Science.gov (United States)

    Karve, Sayali S; Pradhan, Suman; Ward, Doyle V; Weiss, Alison A

    2017-01-01

    Infection with Shiga toxin (Stx) producing Escherichia coli O157:H7 can cause the potentially fatal complication hemolytic uremic syndrome, and currently only supportive therapy is available. Lack of suitable animal models has hindered study of this disease. Induced human intestinal organoids (iHIOs), generated by in vitro differentiation of pluripotent stem cells, represent differentiated human intestinal tissue. We show that iHIOs with addition of human neutrophils can model E. coli intestinal infection and innate cellular responses. Commensal and O157:H7 introduced into the iHIO lumen replicated rapidly achieving high numbers. Commensal E. coli did not cause damage, and were completely contained within the lumen, suggesting defenses, such as mucus production, can constrain non-pathogenic strains. Some O157:H7 initially co-localized with cellular actin. Loss of actin and epithelial integrity was observed after 4 hours. O157:H7 grew as filaments, consistent with activation of the bacterial SOS stress response. SOS is induced by reactive oxygen species (ROS), and O157:H7 infection increased ROS production. Transcriptional profiling (RNAseq) demonstrated that both commensal and O157:H7 upregulated genes associated with gastrointestinal maturation, while infection with O157:H7 upregulated inflammatory responses, including interleukin 8 (IL-8). IL-8 is associated with neutrophil recruitment, and infection with O157:H7 resulted in recruitment of human neutrophils into the iHIO tissue.

  2. Sedimentation Patterns of Toxin-Producing Microcystis Morphospecies in Freshwater Reservoirs

    Directory of Open Access Journals (Sweden)

    Antonio Quesada

    2013-05-01

    Full Text Available Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed remarkable settling fluxes during and after blooms ranging 106–109 cells m−2 d−1, which might represent 0.1%–7.6% of the organic matter settled. A comprehensive analysis of the Valmayor reservoir showed average Microcystis settling rates (0.04 d−1 and velocities (0.7 m d−1 that resembled toxin settling in the same reservoir and were above most reported elsewhere. M. aeruginosa settling rate was significantly higher than that of M. novacekii and M. flos-aquae. Despite the fact that colony sizes did not differ significantly in their average settling rates, we observed extremely high and low rates in large colonies (>5000 cells and a greater influence of a drop in temperature on small colonies (<1000 cells. We found a 4–14 fold decrease in microcystin cell quota in settling Microcystis of the Cogotas and Valmayor reservoirs compared with pelagic populations, and the hypothetical causes of this are discussed. Our study provides novel data on Microcystis settling patterns in Mediterranean Europe and highlights the need for including morphological, chemotypical and physiological criteria to address the sedimentation of complex Microcystis populations.

  3. Sedimentation patterns of toxin-producing Microcystis morphospecies in freshwater reservoirs.

    Science.gov (United States)

    Cirés, Samuel; Wörmer, Lars; Carrasco, David; Quesada, Antonio

    2013-05-03

    Understanding the annual cycle of Microcystis is essential for managing the blooms of this toxic cyanobacterium. The current work investigated the sedimentation of microcystin-producing Microcystis spp. in three reservoirs from Central Spain during the summer and autumn of 2006 and 2007. We confirmed remarkable settling fluxes during and after blooms ranging 10(6)-10(9) cells m(-2) d(-1), which might represent 0.1%-7.6% of the organic matter settled. A comprehensive analysis of the Valmayor reservoir showed average Microcystis settling rates (0.04 d(-1)) and velocities (0.7 m d(-1)) that resembled toxin settling in the same reservoir and were above most reported elsewhere. M. aeruginosa settling rate was significantly higher than that of M. novacekii and M. flos-aquae. Despite the fact that colony sizes did not differ significantly in their average settling rates, we observed extremely high and low rates in large colonies (>5000 cells) and a greater influence of a drop in temperature on small colonies (reservoirs compared with pelagic populations, and the hypothetical causes of this are discussed. Our study provides novel data on Microcystis settling patterns in Mediterranean Europe and highlights the need for including morphological, chemotypical and physiological criteria to address the sedimentation of complex Microcystis populations.

  4. Antibiotic resistance and integrons in Shiga toxin-producing Escherichia coli (STEC

    Directory of Open Access Journals (Sweden)

    Rocío Colello

    2015-03-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC cause hemorrhagic colitis (HC and hemolytic-uremic syndrome in humans (HUS. Cattle are the main reservoir of STEC and transmission to humans occurs through contaminated food and water. Antibiotics are used in pig production systems to combat disease and improve productivity and play a key role in the dissemination of antibiotic resistance genes to the bacteria. Integrons have been identified in resistant bacteria allowing for the acquisition and dissemination of antibiotic resistance genes. STEC strains isolated from humans and animals have developed antibiotic resistance. In our laboratory, 21 non-157 STEC strains isolated from pigs were analyzed to detect class 1 and 2 integrons by PCR. Eight carried integrons, 7 of them harbored intl2. In another study 545 STEC strains were also analyzed for the presence of intl1 and intl2. Strains carrying intl1 belonged to isolates from environment (n = 1, chicken hamburger (n = 2, dairy calves (n = 4 and pigs (n = 8. Two strains isolated from pigs harbored intl2 and only one intl1/intl2, highlighting the presence of intl2 in pigs. The selection for multiresistant strains may contribute to the emergence of antibiotic resistant pathogens and facilitate the spreading of the mobile resistance elements to other bacteria.

  5. Detection of Shiga toxin-producing Escherichia coli by sandwich enzyme-linked immunosorbent assay using chicken egg yolk IgY antibodies

    OpenAIRE

    Parma, Y. R.; Chacana, P. A.; Lucchesi, P. M. A.; Rogé, A.; Granobles Velandia, C. V.; Krüger, A.; Parma, A. E.; Fernández-Miyakawa, M. E.

    2012-01-01

    Enterohemorrhagic Escherichia coli (EHEC), a subset of Shiga toxin producing E. coli (STEC) is associated with a spectrum of diseases that includes diarrhea, hemorrhagic colitis and a life-threatening hemolytic-uremic syndrome (HUS). Regardless of serotype, Shiga toxins (Stx1 and/or Stx2) are uniformly expressed by all EHEC, and so exploitable targets for laboratory diagnosis of these pathogens. In this study, a sandwich ELISA for determination of Shiga toxin (Stx) was developed using anti-St...

  6. Investigation of shiga toxin-producing Escherichia coli in avian species in India.

    Science.gov (United States)

    Wani, S A; Samanta, I; Bhat, M A; Nishikawa, Y

    2004-01-01

    To investigate the presence or absence of shiga toxin-producing Escherichia coli (STEC) in avian species in India. Faecal samples originating from 500 chicken and 25 free flying pigeons were screened for the presence of E. coli. A total of 426 (chicken, 401; pigeons, 25) E. coli strains were isolated. Of 426 E. coli strains, 387 were grouped into 77 serogroups, while 70 and 59 strains were untypable and rough, respectively. All isolates were subjected to multiplex polymerase chain reaction (m-PCR) for the detection of stx(1), stx(2), eaeA, hlyA and saa genes. None of the E. coli strains studied showed the presence of stx(1), stx(2) or their variants and saa genes. Overall 11 (2.74%) and seven (1.74%) strains from chickens possessed eaeA and hlyA genes, respectively, while as only six (1.49%) strains from chickens possessed both eaeA and hlyA genes. O9, O8, O60 and O25 serogroups were most predominant of which there were 24 (5.63%), 23 (5.39%), 23 (5.39%) and 20 (4.69%) strains, respectively. None of the isolates from pigeons showed the presence of any of the virulence genes studied. STEC are absent in chickens and pigeons. However, further studies are required in this direction to confirm or contradict our findings. E. coli strains originating from birds are carrying a low percentage eaeA or hlyA genes. The present study is the first attempt to investigate STEC in chickens and free flying pigeons in India. The chickens and pigeons cannot be considered as important carrier of STEC in India.

  7. Functional and phylogenetic analysis of ureD in Shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Steyert, Susan R; Rasko, David A; Kaper, James B

    2011-02-01

    Enterohemorrhagic Escherichia coli (EHEC) is a food-borne pathogen that can cause severe health complications and utilizes a much lower infectious dose than other E. coli pathotypes. Despite having an intact ure locus, ureDABCEFG, the majority of EHEC strains are phenotypically urease negative under tested conditions. Urease activity potentially assists with survival fitness by enhancing acid tolerance during passage through the stomach or by aiding with colonization in either human or animal reservoirs. Previously, in the EHEC O157:H7 Sakai strain, a point mutation in ureD, encoding a urease chaperone protein, was identified, resulting in a substitution of an amber stop codon for glutamine. This single nucleotide polymorphism (SNP) is observed in the majority of EHEC O157:H7 isolates and correlates with a negative urease phenotype in vitro. We demonstrate that the lack of urease activity in vitro is not solely due to the amber codon in ureD. Our analysis has identified two additional SNPs in ureD affecting amino acid positions 38 and 205, in both cases determining whether the encoded amino acid is leucine or proline. Phylogenetic analysis based on Ure protein sequences from a variety of urease-encoding bacteria demonstrates that the proline at position 38 is highly conserved among Gram-negative bacteria. Experiments reveal that the L38P substitution enhances urease enzyme activity; however, the L205P substitution does not. Multilocus sequence typing analysis for a variety of Shiga toxin-producing E. coli isolates combined with the ureD sequence reveals that except for a subset of the O157:H7 strains, neither the in vitro urease-positive phenotype nor the ureD sequence is phylogenetically restricted.

  8. Characterization of Urinary Tract Infection-Associated Shiga Toxin-Producing Escherichia coli

    Science.gov (United States)

    Toval, Francisco; Schiller, Roswitha; Meisen, Iris; Putze, Johannes; Kouzel, Ivan U.; Zhang, Wenlan; Karch, Helge; Bielaszewska, Martina; Mormann, Michael; Müthing, Johannes

    2014-01-01

    Enterohemorrhagic Escherichia coli (EHEC), a subgroup of Shiga toxin (Stx)-producing E. coli (STEC), is a leading cause of diarrhea and hemolytic-uremic syndrome (HUS) in humans. However, urinary tract infections (UTIs) caused by this microorganism but not associated with diarrhea have occasionally been reported. We geno- and phenotypically characterized three EHEC isolates obtained from the urine of hospitalized patients suffering from UTIs. These isolates carried typical EHEC virulence markers and belonged to HUS-associated E. coli (HUSEC) clones, but they lacked virulence markers typical of uropathogenic E. coli. One isolate exhibited a localized adherence (LA)-like pattern on T24 urinary bladder epithelial cells. Since the glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) are well-known receptors for Stx but also for P fimbriae, a major virulence factor of extraintestinal pathogenic E. coli (ExPEC), the expression of Gb3Cer and Gb4Cer by T24 cells and in murine urinary bladder tissue was examined by thin-layer chromatography and mass spectrometry. We provide data indicating that Stxs released by the EHEC isolates bind to Gb3Cer and Gb4Cer isolated from T24 cells, which were susceptible to Stx. All three EHEC isolates expressed stx genes upon growth in urine. Two strains were able to cause UTI in a murine infection model and could not be outcompeted in urine in vitro by typical uropathogenic E. coli isolates. Our results indicate that despite the lack of ExPEC virulence markers, EHEC variants may exhibit in certain suitable hosts, e.g., in hospital patients, a uropathogenic potential. The contribution of EHEC virulence factors to uropathogenesis remains to be further investigated. PMID:25156739

  9. Factors Associated with Shiga Toxin-Producing Escherichia coli Shedding by Dairy and Beef Cattle

    Science.gov (United States)

    Venegas-Vargas, Cristina; Henderson, Scott; Khare, Akanksha; Mosci, Rebekah E.; Lehnert, Jonathan D.; Singh, Pallavi; Ouellette, Lindsey M.; Norby, Bo; Funk, Julie A.; Rust, Steven; Bartlett, Paul C.; Grooms, Daniel

    2016-01-01

    ABSTRACT Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen that can cause hemorrhagic colitis and hemolytic-uremic syndrome. Cattle are the primary reservoir for STEC, and food or water contaminated with cattle feces is the most common source of infections in humans. Consequently, we conducted a cross-sectional study of 1,096 cattle in six dairy herds (n = 718 animals) and five beef herds (n = 378 animals) in the summers of 2011 and 2012 to identify epidemiological factors associated with shedding. Fecal samples were obtained from each animal and cultured for STEC. Multivariate analyses were performed to identify risk factors associated with STEC positivity. The prevalence of STEC was higher in beef cattle (21%) than dairy cattle (13%) (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.25, 2.47), with considerable variation occurring across herds (range, 6% to 54%). Dairy cattle were significantly more likely to shed STEC when the average temperature was >28.9°C 1 to 5 days prior to sampling (OR, 2.5; 95% CI, 1.25, 4.91), during their first lactation (OR, 1.8; 95% CI, 1.1, 2.8), and when they were Dairy cattle sampled at higher temperatures, in their first lactation, and early in the milk production stage were significantly more likely to shed STEC, which could be due to stress or a negative energy balance. Future studies should focus on the isolation of high-risk animals to decrease herd shedding levels and the potential for contamination of the food supply. PMID:27342555

  10. Methicillin sensitive Staphylococcus aureus producing Panton-Valentine leukocidin toxin in Trinidad & Tobago: a case report

    Directory of Open Access Journals (Sweden)

    Rao AV

    2011-04-01

    Full Text Available Abstract Introduction Certain Staphylococcus aureus strains produce Panton-Valentine leukocidin, a toxin that lyses white blood cells causing extensive tissue necrosis and chronic, recurrent or severe infection. This report documents a confirmed case of methicillin-sensitive Staphylococcus aureus strain harboring Panton-Valentine leukocidin genes from Trinidad and Tobago. To the best of our knowledge, this is the first time that such a case has been identified and reported from this country. Case presentation A 13-year-old Trinidadian boy of African descent presented with upper respiratory symptoms and gastroenteritis-like syptoms. About two weeks later he was re-admitted to our hospital complaining of pain and weakness affecting his left leg, where he had received an intramuscular injection of an anti-emetic drug. He deteriorated and developed septic arthritis, necrotizing fasciitis and septic shock with acute respiratory distress syndrome, leading to death within 48 hours of admission despite intensive care treatment. The infection was caused by S. aureus. Bacterial isolates from specimens recovered from our patient before and after his death were analyzed using microarray DNA analysis and spa typing, and the results revealed that the S. aureus isolates belonged to clonal complex 8, were methicillin-susceptible and positive for Panton-Valentine leukocidin. An autopsy revealed multi-organ failure and histological tissue stains of several organs were also performed and showed involvement of his lungs, liver, kidneys and thymus, which showed Hassal's corpuscles. Conclusion Rapid identification of Panton-Valentine leukocidin in methicillin-sensitive S. aureus isolates causing severe infections is necessary so as not to miss their potentially devastating consequences. Early feedback from the clinical laboratories is crucial.

  11. Evaluation of eight agar media for the isolation of shiga toxin-Producing Escherichia coli.

    Science.gov (United States)

    Gill, Alexander; Huszczynski, George; Gauthier, Martine; Blais, Burton

    2014-01-01

    The growth characteristics of 96 shiga toxin-producing Escherichia coli (STEC) strains representing 36 different O-types (including priority O types O26, O45, O103, O111, O121, O145 and O157) on commercial and in-house agar media were studied. The ability of the strains to grow on agar media with varying selective supplement formulations was evaluated using MacConkey Agar (MAC); Rainbow® Agar O157 (RBA); Rainbow® Agar O157 with manufacturer-recommended selective supplements (RBA-NT); Rainbow® Agar O157 with USDA-recommended selective supplements (RBA-USDA); CHROMagar STEC™ (CH STEC); Tryptone Bile agar containing cefixime and tellurite (TBA-CT); Tryptone Bile agar containing cefixime, tellurite, eosin and methylene blue (TBA-EM); and VTEC agar. All of the strains were able to grow on MAC, RBA and VTEC agar, whereas a number of strains (including some non-O157 priority O types) were unable to grow on the highly selective media CH STEC, RBA-NT, RBA-USDA, TBA-EM and TBA-CT. Only RBA-NT and CH STEC exhibited significant inhibition of background flora from ground beef enrichment. Significant inhibition of background flora from beef trim enrichment was observed with RBA-NT, RBA-USDA, CH STEC, TBA-EM and VTEC agar. With exception of E. coli O157, several different colony morphologies were observed on the differential plating media among strains of the same O type, indicating that this colony morphology is not a reliable means of identifying target STEC. These results suggest that an approach to maximize the recovery of target STEC from beef enrichment cultures is dual plating on lesser (RBA, MAC, VTEC agar) and more highly (RBA-NT, CH STEC) selective agars. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  12. Role of climate in the spread of shiga toxin-producing Escherichia coli infection among children

    Science.gov (United States)

    Acquaotta, Fiorella; Ardissino, Gianluigi; Fratianni, Simona; Perrone, Michela

    2017-09-01

    Haemolytic-uraemic syndrome (HUS) is a rare disease mainly affecting children that develops as a complication of shiga toxin-producing Escherichia coli (STEC) infection. It is characterised by acute kidney injury, platelet consumption and mechanical destruction of red blood cells (haemolysis). In order to test the working hypothesis that the spread of the infection is influenced by specific climatic conditions, we analysed all of the identified cases of infection occurring between June 2010 and December 2013 in four provinces of Lombardy, Italy (Milano, Monza Brianza, Varese and Brescia), in which a STEC surveillance system has been developed as part of a preventive programme. In the selected provinces, we recorded in few days a great number of cases and clusters which are unrelated for spatially distant or for the disease are caused by different STEC serotypes. In order to investigate a common factor that favoured the onset of infection, we have analysed in detail the weather conditions of the areas. The daily series of temperature, rain and relative humidity were studied to show the common climate peculiarities whilst the correlation coefficient and the principal component analysis (PCA) were used to point out the meteorological variable, maximum temperature, as the principal climate element in the onset of the infection. The use of distributed lag non-linear models (DLNM) and the climate indices characterising heat waves (HWs) has allowed to identify the weather conditions associated with STEC infection. The study highlighted a close temporal correlation between STEC infection in children and the number, duration and frequency of heat waves. In particular, if the maximum temperature is greater than 90th percentile, days classified as very hot, for 3 or more consecutive days, the risk of infection is increasing.

  13. Clinical Evaluation and Cost Analysis of Great Basin Shiga Toxin Direct Molecular Assay for Detection of Shiga Toxin-Producing Escherichia coli in Diarrheal Stool Specimens.

    Science.gov (United States)

    Faron, Matthew L; Ledeboer, Nathan A; Connolly, Jessica; Granato, Paul A; Alkins, Brenda R; Dien Bard, Jennifer; Daly, Judy A; Young, Stephen; Buchan, Blake W

    2017-02-01

    The Shiga Toxin Direct molecular assay (ST Direct) relies on nucleic acid amplification and solid array-based amplicon detection to identify Shiga toxin-producing Escherichia coli (STEC) in preserved stool specimens. Genes encoding Shiga toxin (stx 1 and stx 2 ), as well as the E. coli serotype O:157-specific marker rfbE, are simultaneously detected within 2 h. ST Direct was evaluated using 1,084 prospectively collected preserved stool specimens across five clinical centers. An additional 55 retrospectively collected, frozen specimens were included to increase the number of positive specimens evaluated. Results were compared to results from routine culture and an enzyme immunoassay (EIA) specific for the recovery and identification of STEC. ST Direct was found to be 93.2% sensitive and 99.3% specific for detection of stx 1 and stx 2 and 95.7% sensitive and 99.3% specific for detection of E. coli serotype O:157. All specimens with false-positive results were found to contain stx 1 or stx 2 or were found to be positive for serotype O:157 when analyzed using alternative molecular methods. All 4 false-negative stx 1 or stx 2 results were reported for frozen, retrospectively tested specimens. In all cases, the specimens tested positive for stx by an alternative FDA-cleared nucleic acid amplification test (NAAT) but were negative for stx 1 and stx 2 following nucleic acid sequence analysis. Based on these data, culture and EIA-based methods for detection of STEC are only 33% sensitive compared to molecular tests. A retrospective cost analysis demonstrated 59% of the cost of routine stool culture to be attributable to the identification of STEC. Taken together, these data suggest that ST Direct may provide a cost-effective, rapid molecular alternative to routine culture for the identification of STEC in preserved stool specimens. Copyright © 2017 American Society for Microbiology.

  14. Effects of stresses on the growth and Cytotoxicity of Shiga-Toxin producing Escherichia coli in ground beef and spinach

    Science.gov (United States)

    The objectives of this study were to examine the effect of stresses on the growth and cytotoxicity of pathogenic Escherichia coli in beef and spinach. A mixture of three strains of Shiga toxin-producing E. coli (STEC) O157:H7 or four strains of non-O157 STEC O26:H11, O103:H1, O104:H4, and O145:NM wa...

  15. Short communication: Detection of Shiga toxin-producing Escherichia coli (STEC) in healthy cattle and pigs in Lima, Peru.

    Science.gov (United States)

    Rivera, F P; Sotelo, E; Morales, I; Menacho, F; Medina, A M; Evaristo, R; Valencia, R; Carbajal, L; Ruiz, J; Ochoa, T J

    2012-03-01

    The aim of this study was to determine the prevalence of Shiga toxin-producing Escherichia coli (STEC) in cattle and pigs as a possible STEC reservoir in Lima, Peru. One hundred and fourteen cattle and 112 pigs from 10 and 4 farms, respectively, were studied. Five E. coli colonies per culture were studied by a multiplex real-time PCR to identify Shiga toxin-producing (stx1, stx2, eaeA), enterotoxigenic (lt, st), enteropathogenic (eaeA), enteroinvasive (ipaH), enteroaggregative (aggR), and diffusely adherent E. coli (daaD). Shiga toxin-producing E. coli were isolated from 16 cattle (14%) but none from pigs. stx1 was found in all bovine isolates, 11 of which also carried eaeA genes (69%); only 1 sample had both stx1 and stx2. Thirteen stx-positive strains were classified as Shiga-toxigenic (81%) using an enzymatic immunoassay, 2 STEC strains were from serogroup O157 (13%), and 7 were sorbitol negative (44%). Enteropathogenic E. coli were detected more frequently in cattle (18%, 20/114) than in pigs (5%, 6/112). To our knowledge, this is the first study on the prevalence of STEC in farms animals in Peru using molecular methods. Further studies are needed in a large number of farms to determine the relevance of these findings and its consequences for public health. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  16. Implications of free Shiga toxin-converting bacteriophages occurring outside bacteria for the evolution and the detection of Shiga toxin-producing Escherichia coli

    Directory of Open Access Journals (Sweden)

    Alexandre eMartinez-Castillo

    2014-04-01

    Full Text Available In this review we highlight recent work that has increased our understanding of the distribution of Shiga toxin-converting phages that can be detected as free phage particles, independently of Shiga toxin-producing bacteria (STEC. Stx phages are a quite diverse group of temperate phages that can be found in their prophage state inserted within the STEC chromosome, but can also be found as phages released from the cell after activation of their lytic cycle. They have been detected in extraintestinal environments such as water polluted with feces from humans or animals, food samples or even in stool samples of healthy individuals. The high persistence of phages to several inactivation conditions makes them suitable candidates for the successful mobilization of stx genes, possibly resulting in the genes reaching a new bacterial genomic background by means of transduction, where ultimately they may be expressed, leading to Stx production. Besides the obvious fact that Stx phages circulating between bacteria can be, and probably are, involved in the emergence of new STEC strains, we review here other possible ways in which free Stx phages could interfere with the detection of STEC in a given sample by current laboratory methods and how to avoid such interference.

  17. HicA toxin of Escherichia coli derepresses hicAB transcription to selectively produce HicB antitoxin.

    Science.gov (United States)

    Turnbull, Kathryn J; Gerdes, Kenn

    2017-06-01

    Antitoxins encoded by type II toxin - antitoxin (TA) modules neutralize cognate toxins by direct protein - protein contact and in addition, regulate TA operon transcription by binding to operators in the promoter regions. On top of the simple negative feed-back regulation, canonical type II TA operons are regulated by a mechanism called 'Conditional Cooperativity'(CC). In CC, the cellular toxin:antitoxin (T:A) ratio controls the transcription-rate such that low T:A ratios favour repression and high T:A ratios favour de-repression of TA operon transcription. Here a new molecular mechanism that secures selective synthesis of antitoxin in the presence of excess toxin was unravelled. The hicAB locus of E. coli K-12 encodes HicA mRNase and HicB antitoxin. It was shown that hicAB is transcribed by two promoters, an upstream one that is activated by CRP-cAMP and competence factor Sxy and a downstream one that is autorepressed solely by HicB. Excess HicA destabilizes the HicB•operator complex in vitro and consistently, activates hicAB transcription in vivo. Remarkably, the hicAB transcript synthesized from the HicB-controlled promoter produces HicB but not HicA. Thus, the HicA-mediated derepression of hicAB transcription provides a mechanism that conditionally and selectively stimulates synthesis of HicB antitoxin under conditions of excess HicA toxin. © 2017 John Wiley & Sons Ltd.

  18. Inclusion Mechanism and Heat Stability of the Complex of 4 ...

    African Journals Online (AJOL)

    Purpose: To study the inclusion mechanism and heat stability of the complex formed between 4'- hydroxychalcone and hydroxypropyl-β-cyclodextrin Methods: The inclusion mechanism of the complex of 4'-hydroxychalcone and HP-β-CD was investigated by phase solubility method. The physicochemical properties of the ...

  19. Concentrated whey protein particle dispersions: Heat stability and rheological properties

    NARCIS (Netherlands)

    Saglam, D.; Venema, P.; Vries, de R.J.; Shi, J.; Linden, van der E.

    2013-01-01

    In this work heat stability and rheological properties of concentrated whey protein particle dispersions in different dispersing media are studied. Whey protein particles (protein content ~20% w/v) having an average size of a few microns were formed using a combination of two-step emulsification and

  20. Production and regulation of functional amyloid curli fimbriae by Shiga toxin-producing Escherichia coli

    Science.gov (United States)

    Functional amyloid, in the form of adhesive fimbrial proteins termed curli, was first described in Salmonella and Escherichia coli. Curli fibers adhere to various host cells and structural proteins, interact with components of the host immune system, and participate in biofilm formation. Shiga toxin...

  1. Exopolysaccharides produced by Lactobacillus and Bifidobacterium strains abrogate in vitro the cytotoxic effect of bacterial toxins on eukaryotic cells.

    Science.gov (United States)

    Ruas-Madiedo, P; Medrano, M; Salazar, N; De Los Reyes-Gavilán, C G; Pérez, P F; Abraham, A G

    2010-12-01

    To evaluate the capability of the exopolysaccharides (EPS) produced by lactobacilli and bifidobacteria from human and dairy origin to antagonize the cytotoxic effect of bacterial toxins. The cytotoxicity of Bacillus cereus extracellular factors on Caco-2 colonocytes in the presence/absence of the EPS was determined by measuring the integrity of the tissue monolayer and the damage to the cell membrane (extracellular lactate dehydrogenase activity). Additionally, the protective effect of EPS against the haemolytic activity of the streptolysin-O was evaluated on rabbit erythrocytes. The EPS produced by Bifidobacterium animalis ssp. lactis A1 and IPLA-R1, Bifidobacterium longum NB667 and Lactobacillus rhamnosus GG were able to counteract the toxic effect of bacterial toxins on the eukaryotic cells at 1mg ml(-1) EPS concentration. The EPS A1 was the most effective in counteracting the effect of B. cereus toxins on colonocytes, even at lower doses (0·5mg ml(-1) ), whereas EPS NB667 elicited the highest haemolysis reduction on erythrocytes. The production of EPS by lactobacilli and bifidobacteria could antagonize the toxicity of bacterial pathogens, this effect being EPS and biological marker dependent. This work allows gaining insight about the mechanisms that probiotics could exert to improve the host health. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

  2. Differential heat stability of amphenicols characterized by structural degradation, mass spectrometry and antimicrobial activity.

    Science.gov (United States)

    Franje, Catherine A; Chang, Shao-Kuang; Shyu, Ching-Lin; Davis, Jennifer L; Lee, Yan-Wen; Lee, Ren-Jye; Chang, Chao-Chin; Chou, Chi-Chung

    2010-12-01

    Heat stability of amphenicols and the relationship between structural degradation and antimicrobial activity after heating has not been well investigated. Florfenicol (FF), thiamphenicol (TAP), and chloramphenicol (CAP) were heated at 100 degrees C in water, salt water, soybean sauce and chicken meat for up to 2h. Degradation and antimicrobial activity of the compounds was evaluated using capillary electrophoresis (CE) with UV-DAD spectrometry, minimum inhibitory concentration (MIC) assay, and gas chromatography with electron impact ionization mass spectrometry (GC-EI-MS). Heat stability of amphenicols in matrices was ranked as water> or =salt water>soybean sauce>meat, suggesting that heat degradation of amphenicols was accelerated in soybean sauce and was not protected in meat. Heat stability by drug and matrices was ranked as FF>TAP=CAP in water, FF=TAP>CAP in salt water, TAP> or =FF=CAP in soybean sauce, and TAP> or =FF=CAP in meat, indicating differential heat stability of amphenicols among the 3 drugs and in different matrices. In accordance with the less than 20% degradation, the MIC against Escherichia coli and Staphylococcus aureus did not change after 2h heating in water. A 5-min heating of amphenicols in water by microwave oven generated comparable percentage degradation to boiling in water bath for 30 min to 1h. Both CE and GC-MS analysis showed that heating of FF produced TAP but not FF amine as one of its breakdown products. In conclusion, despite close similarity in structure; amphenicols exhibited differential behavior toward heating degradation in solutions and protein matrices. Although higher degradations of amphenicols were observed in soybean sauce and meat, heating treatment may generate product with antimicrobial activity (FF to TAP), therefore, heating of amphenicol residues in food cannot always be assumed safe. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  3. Characterization and zoonotic impact of Shiga toxin producing Escherichia coli in some wild bird species

    Directory of Open Access Journals (Sweden)

    Hanaa Mohamed Fadel

    2017-09-01

    Full Text Available Aim: Wild birds are considered silent vectors of some zoonotic water and food borne pathogens of public health significance. Owing to the importance of Shiga toxin producing Escherichia coli (STEC as the most pathogenic among the emerging diarrheagenic E. coli groups that can infect man; the present study was designed to detect the occurrence of STEC among wild birds in Egypt. Materials and Methods: A total of 177 intestinal content swab samples originating from five wild bird species were investigated for the presence of E. coli and STEC by standard culture methods. Suspect STEC isolates were further characterized by serotyping, random amplified polymorphic DNA polymerase chain reaction (RAPD PCR, antimicrobial resistance pattern and PCR detection of stx1, stx2, and eae genes. Results: A total of 30 suspect STEC isolates from 30 positive birds' samples were detected and identified on STEC CHROMagar (semi-captive pigeons, 15; house crows, 8; cattle egrets, 3; moorhens, 2; and house teals, 2. 25 isolates were grouped into 13 serogroups (O:20, O:25, O:26, O:27, O:63, O:78, O:111, O:114, O:125, O:128, O:142, O:153, and O:158, while five were rough strains. The distribution of STEC virulence genes among wild birds was as follows: 16 birds carried stx1 gene only (nine pigeons [28.1%], six crows [7.1%], and one cattle egret [5.6%]. stx1 and stx2 genes together were detected in four birds (one cattle egret [5.6%], two moorhens [6.1%], and one house teal, [10%]. Only one pigeon (3.1% possessed the three alleles. Disk diffusion test results showed that cefixime was the most effective against STEC serotypes with (93.3% sensitivity, followed by gentamycin (56.7%, and amoxicillin (50%. On the other hand, all the recovered STEC isolates were resistant to cefotaxime, doxycycline, cephalothin, and sulfisoxazole. RAPD fingerprinting using primers OPA-2 and OPA-9 showed that STEC isolates were heterogeneous; they yielded 30 and 27 different clusters

  4. Epidemiology of Shiga toxin producing Escherichia coli in Australia, 2000-2010

    Science.gov (United States)

    2012-01-01

    Background Shiga toxin-producing Escherichia coli (STEC) are an important cause of gastroenteritis in Australia and worldwide and can also result in serious sequelae such as haemolytic uraemic syndrome (HUS). In this paper we describe the epidemiology of STEC in Australia using the latest available data. Methods National and state notifications data, as well as data on serotypes, hospitalizations, mortality and outbreaks were examined. Results For the 11 year period 2000 to 2010, the overall annual Australian rate of all notified STEC illness was 0.4 cases per 100,000 per year. In total, there were 822 STEC infections notified in Australia over this period, with a low of 1 notification in the Australian Capital Territory (corresponding to a rate of 0.03 cases per 100,000/year) and a high of 413 notifications in South Australia (corresponding to a rate of 2.4 cases per 100,000/year), the state with the most comprehensive surveillance for STEC infection in the country. Nationally, 71.2% (504/708) of STEC infections underwent serotype testing between 2001 and 2009, and of these, 58.0% (225/388) were found to be O157 strains, with O111 (13.7%) and O26 (11.1%) strains also commonly associated with STEC infections. The notification rate for STEC O157 infections Australia wide between 2001-2009 was 0.12 cases per 100,000 per year. Over the same 9 year period there were 11 outbreaks caused by STEC, with these outbreaks generally being small in size and caused by a variety of serogroups. The overall annual rate of notified HUS in Australia between 2000 and 2010 was 0.07 cases per 100,000 per year. Both STEC infections and HUS cases showed a similar seasonal distribution, with a larger proportion of reported cases occurring in the summer months of December to February. Conclusions STEC infections in Australia have remained fairly steady over the past 11 years. Overall, the incidence and burden of disease due to STEC and HUS in Australia appears comparable or lower than

  5. Genotypes and phenotypes of Shiga toxin-producing Escherichia coli (STEC in Abeokuta, Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Olowe OA

    2014-10-01

    Full Text Available Olugbenga Adekunle Olowe,1 Bukola W Aboderin,1,2 Olayinka O Idris,3 Victor O Mabayoje,4 Oluyinka O Opaleye,1 O Catherine Adekunle,1 Rita Ayanbolade Olowe,1 Paul Akinniyi Akinduti,5 Olusola Ojurongbe1 1Department of Medical Microbiology and Parasitology, College of Health Sciences, Osogbo, Osun State, Nigeria; 2Medical Microbiology Unit, Pathology Department, Federal Medical Centre, Abeokuta, Nigeria; 3Department of Microbiology, College of Sciences, Afe Babalola University, Ado Ekiti, Nigeria; 4Department of Haematology, College of Health Sciences, Ladoke Akintola University, Osogbo, Osun State, Nigeria; 5Department of Medical Microbiology and Parasitology, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria Purpose: To characterize the prevalence of hemolytic Shiga toxin-producing Escherichia coli (STEC with a multidrug-resistant pattern in different age groups in Abeokuta, Nigeria. Methods: Nonrepetitive E. coli isolates were collected from 202 subjects with or without evidence of diarrhea. Each isolate was biochemically identified and antimicrobial susceptibility testing was performed using the disk diffusion method. A sorbitol fermentation test of all the E. coli isolates was done and the minimum inhibitory concentration of suspected STEC was measured by the standard broth microdilution method to determine antibiotic resistance. The genotypes of stx1, stx2, and hlyA were determined by polymerase chain reaction assay. Results: The majority of subjects were aged ≥40 years (41.6% and were female (61.9%. Of the 202 subjects, 86.1% had STEC isolates (P<0.05. A high rate of STEC isolates resistant to amoxicillin (90.6%, cefotaxime (77.7%, and cefuroxime (75.7% was observed. Resistance to amoxicillin, gentamicin, and cefotaxime was demonstrated with a minimum inhibitory concentration >16 µg/mL in 13.9%, 11.4%, and 10.4% of the isolates, respectively. The prevalence of stx1, stx2, and hlyA was 13.9%, 6.9%, and 2.0%, respectively; 5.5% of

  6. Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

    OpenAIRE

    Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J.; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Van Minh, Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    Background Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in ?backyard? farms in south-east Asia. Results Faecal samples collected...

  7. Shiga toxin-producing Escherichia coli O157:H7 in milk and milk products in Ogun State, Nigeria.

    Science.gov (United States)

    Ivbade, Akhigbe; Ojo, Olufemi Ernest; Dipeolu, Morenike Atinuke

    2014-01-01

    Shiga toxin producing Escherichia coli (STEC) O157 is a major cause of food-borne illnesses in humans. This study investigated the presence of STEC O157 in milk and milk products in Ogun State, Nigeria. Of a total of 202 samples 10 (5%) were positive for STEC O157 including 1 (2%) of 50 raw milk samples, 3 (6%) of 50 samples of fresh local cheese, 1 (2%) of 50 samples of fried local cheese and 5 (9.6%) of 52 fermented milk samples. There was no significant difference (p>0.05) in the prevalence of STEC O157 among the sample types. Of 10 isolates, shiga toxin 1 gene (stx1) was detected only in 2 samples (20%), shiga toxin 2 (stx2) was extracted only in 6 samples (60%), stx1 /stx2 in 2 samples (20.0%), intimin gene (eaeA) in 5 samples (50%), and enterohaemolysin (E-hlyA) gene was isolated in 7 (70%) samples. Rates of resistance of the STEC O157 isolates were: amoxicillin/clavulanic acid 100%, ampicillin 100%, chloramphenicol 60%, nalidixic acid 20%, norfloxacin 10%, streptomycin 30%, sulphamethoxazole/trimethprim 20%, and tetracycline 90%. The isolates were all susceptible to ciprofloxacin and neomycin. The presence of virulent multidrug resistant E. coli O157 strains in milk and milk products as revealed by this study unveils a risk of human exposure to these potentially fatal pathogens following consumption of contaminated products.

  8. Detection of Escherichia coli Shiga toxin-producing in viscera of animals bovine and chicken intended for human consumption

    Directory of Open Access Journals (Sweden)

    Zotta, Claudio Marcelo

    2016-05-01

    Full Text Available Escherichia coli producing-Shiga toxin (STEC is associated with foodborne illness (ETA. It can cause bloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. The aim of the study was to detect the presence of STEC in samples of organs (offal of bovine animals and chicken intended for human consumption. Between 2008-2009, 76 samples bovine entrails and 22 chicken viscera samples, were processed and underwent, as screening technique, the polymerase chain reaction (PCR for detection of multiple genes coding for the factors virulence: Shiga toxin (stx1, stx2 and rfbO157 gene coding for capsular O157 lipopolysaccharide LPS. Samples from bovine offal development showed 84.2% for coliform bacteria. These isolates showed no virulence factor that characterized as STEC or Escherichia coli O157. The chicken offal samples showed 95.5% of development for coliform bacteria, being negative for the presence of genes encoding the Shiga toxins 1 and 2 (stx1, stx2 and rfbO157 gene. While this work does not STEC was detected, the presence of coliform bacteria in the samples studied makes these foods should be considered as potentially hazardous to consume undercooked with the consequent possibility of filing ETA.

  9. Prevalence and characteristics of shiga toxin-producing Escherichia coli in beef cattle slaughtered on Prince Edward Island.

    Science.gov (United States)

    Schurman, R D; Hariharan, H; Heaney, S B; Rahn, K

    2000-11-01

    Fecal swabs obtained from a random sample of 1,000 beef slaughter steers and heifers from 123 Prince Edward Island (P.E.I.) farms were examined for the presence of Shiga toxin-producing Escherichia coli (STEC) using a Vero cell assay (VCA). Multiple isolates from each positive sample were tested similarly. VCA-positive isolates were confirmed as E. coli biochemically, tested for drug resistance, serotyped, and tested by polymerase chain reaction (PCR). Animals were classified as positive when an isolate was positive on VCA and the presence of the gene responsible for toxin production was confirmed by PCR. The prevalence of STEC in beef slaughter steers and heifers on P.E.I. was 4% (40 of 1,000). The total number of isolates was 43, and these comprised 26 serotypes, including 13 isolates belonging to 6 serotypes known to be associated with human illness. The most frequently isolated STEC serotype was E. coli O157 (5 isolates out of 43). Of the five E. coli O157 isolates, four were E. coli O157:H7, a serious human pathogen. The majority of STEC isolates, including all O157:H7, isolates, were susceptible to 16 commonly used antimicrobial drugs. According to PCR, 65% of the STEC isolates had the gene for Stx1. Four of these isolates, including two O157:H7, had genes for Shiga toxin (Stx)1 and Stx2.

  10. Real-Time PCR Assay for Detection and Differentiation of Shiga Toxin-Producing Escherichia coli from Clinical Samples

    Science.gov (United States)

    Klein, Eileen J.; Galanakis, Emmanouil; Thomas, Anita A.; Stapp, Jennifer R.; Rich, Shannon; Buccat, Anne Marie; Tarr, Phillip I.

    2015-01-01

    Timely accurate diagnosis of Shiga toxin-producing Escherichia coli (STEC) infections is important. We evaluated a laboratory-developed real-time PCR (LD-PCR) assay targeting stx1, stx2, and rfbEO157 with 2,386 qualifying stool samples submitted to the microbiology laboratory of a tertiary care pediatric center between July 2011 and December 2013. Broth cultures of PCR-positive samples were tested for Shiga toxins by enzyme immunoassay (EIA) (ImmunoCard STAT! enterohemorrhagic E. coli [EHEC]; Meridian Bioscience) and cultured in attempts to recover both O157 and non-O157 STEC. E. coli O157 and non-O157 STEC were detected in 35 and 18 cases, respectively. Hemolytic uremic syndrome (HUS) occurred in 12 patients (10 infected with STEC O157, one infected with STEC O125ac, and one with PCR evidence of STEC but no resulting isolate). Among the 59 PCR-positive STEC specimens from 53 patients, only 29 (54.7%) of the associated specimens were toxin positive by EIA. LD-PCR differentiated STEC O157 from non-O157 using rfbEO157, and LD-PCR results prompted successful recovery of E. coli O157 (n = 25) and non-O157 STEC (n = 8) isolates, although the primary cultures and toxin assays were frequently negative. A rapid “mega”-multiplex PCR (FilmArray gastrointestinal panel; BioFire Diagnostics) was used retrospectively, and results correlated with LD-PCR findings in 25 (89%) of the 28 sorbitol-MacConkey agar culture-negative STEC cases. These findings demonstrate that PCR is more sensitive than EIA and/or culture and distinguishes between O157 and non-O157 STEC in clinical samples and that E. coli O157:H7 remains the predominant cause of HUS in our institution. PCR is highly recommended for rapid diagnosis of pediatric STEC infections. PMID:25926491

  11. Characteristics of shiga toxin-producing Escherichia coli isolated from Swiss raw milk cheese within a 3-year monitoring program.

    Science.gov (United States)

    Zweifel, C; Giezendanner, N; Corti, S; Krause, G; Beutin, L; Danuser, J; Stephan, R

    2010-01-01

    Food is an important vehicle for transmission of Shiga toxin-producing Escherichia coli (STEC). To assess the potential public health impact of STEC in Swiss raw milk cheese produced from cow's, goat's, and ewe's milk, 1,422 samples from semihard or hard cheese and 80 samples from soft cheese were examined for STEC, and isolated strains were further characterized. By PCR, STEC was detected after enrichment in 5.7% of the 1,502 raw milk cheese samples collected at the producer level. STEC-positive samples comprised 76 semihard, 8 soft, and 1 hard cheese. By colony hybridization, 29 STEC strains were isolated from 24 semihard and 5 soft cheeses. Thirteen of the 24 strains typeable with O antisera belonged to the serogroups O2, O22, and O91. More than half (58.6%) of the 29 strains belonged to O:H serotypes previously isolated from humans, and STEC O22:H8, O91:H10, O91:H21, and O174:H21 have also been identified as agents of hemolytic uremic syndrome. Typing of Shiga toxin genes showed that stx(1) was only found in 2 strains, whereas 27 strains carried genes encoding for the Stx(2) group, mainly stx(2) and stx(2vh-a/b). Production of Stx(2) and Stx(2vh-a/b) subtypes might be an indicator for a severe outcome in patients. Nine strains harbored hlyA (enterohemorrhagic E. coli hemolysin), whereas none tested positive for eae (intimin). Consequently, semihard and hard raw milk cheese may be a potential source of STEC, and a notable proportion of the isolated non-O157 STEC strains belonged to serotypes or harbored Shiga toxin gene variants associated with human infections.

  12. Development of a typing system for epidemiological studies of porcine toxin-producing Pasteurella multocida ssp. multocida in Denmark

    DEFF Research Database (Denmark)

    Fussing, V.; Nielsen, Jens; Bisgaard, M.

    1999-01-01

    The aim of the present study was to evaluate capsular-typing, plasmid-profiling, phage-typing and ribotyping for epidemiological studies of toxin-producing Pasteurella multocida ssp. multocida in Denmark. The evaluation of methods was based on 68 strains from nasal swabs and 14 strains from...... by HindIII ribotyping, as 85% of isolates from all herds were assigned to one ribotype. In conclusion, HindIII ribotyping seems to represent a useful tool for epidemiological studies of toxigenic P. multocida ssp. multocida....

  13. Comparison of heat stability of goat milk subjected to ultra-high temperature and in-container sterilization.

    Science.gov (United States)

    Chen, B Y; Grandison, A S; Lewis, M J

    2012-03-01

    Goat milk with and without stabilizing salt was subjected to in-container and UHT sterilization. Heat stability was assessed by measuring the amount of sediment in the milk. Without stabilizing salts, goat milk usually produced less sediment when subjected to in-container sterilization compared with UHT processing. Addition of stabilizing salts up to 12.8mM resulted in a progressive increase in sediment for in-container sterilization. In contrast, adding stabilizing salts at 6.4mM initially reduced sediment formation in UHT-treated milk but addition of stabilizing salts at 12.8mM increased sediment formation. Adding stabilizing salts to goat milk increased pH, decreased ionic calcium, and increased ethanol stability. Adding up to 2mM calcium chloride increased sediment formation more after UHT treatment than after in-container sterilization. These results suggest that no single mechanism or set of reactions causes milk to produce sediment during heating and that the favored pathway is different for UHT and in-container sterilization processes. Poor heat stability could be induced both by increasing ionic calcium and by decreasing it. Ethanol stability is not a good indicator of heat stability for in-container sterilization, but it may be for UHT sterilization, if milk does not enter the region of poor heat stability found at low concentrations of ionic calcium. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. Sorbitol-fermenting Shiga toxin-producing Escherichia coli O157 in Austria.

    Science.gov (United States)

    Orth, Dorothea; Grif, Katharina; Zimmerhackl, Lothar Bernd; Würzner, Reinhard

    2009-01-01

    Infections with enterohemorrhagic Escherichia coli (EHEC) are the major cause of hemolytic uremic syndrome (HUS), the most common cause of acute renal failure in childhood. Shiga toxins are considered to be the most important virulence factor of EHEC strains. Non-sorbitol-fermenting EHEC O157:H7 is still the most prevalent serotype isolated worldwide; however, sorbitol-fermenting (SF) EHEC O157:H- (H- indicates nonmotility) strains are increasingly reported. Thirteen SF EHEC O157:H- strains (11 of human origin, two from animals) were detected in Austria between 2002 and 2008. Among the 11 human cases, seven suffered from HUS, two from diarrhea and the remaining two were asymptomatic. Seven of the cases were identified in patients living in or visiting (in one case) the province Salzburg, four were in patients from the province Vorarlberg. Three outbreaks with no more than three persons involved were detected, the other four cases occurred sporadically. The pulsed-field gel-electrophoresis banding patterns of the 13 SF EHEC O157:H- isolates were grouped into three distinct clusters (groups 1, 2 and 3). Strains of the three outbreaks were identical (except for one outbreak strain with one band difference) within each outbreak. In comparison, the Bavarian epidemic strain showed a pattern different from all SF O157:H- strains isolated in Austria. For effective detection of SF EHEC O157:H-, screening for Shiga toxins by ELISA and/or Shiga toxin genes by PCR is absolutely necessary; screening on the basis of phenotypic characteristics such as sorbitol-non-fermentation is not sufficient. Typing methods relying solely on investigation of O157 will detect these strains but should nevertheless also be avoided, so that the prevalent non-O157 strains causing HUS are not missed.

  15. The cultivation of Bt corn producing Cry1Ac toxins does not adversely affect non-target arthropods.

    Directory of Open Access Journals (Sweden)

    Yanyan Guo

    Full Text Available Transgenic corn producing Cry1Ac toxins from Bacillus thuringiensis (Bt provides effective control of Asian corn borer, Ostrinia furnacalis (Guenée, and thus reduces insecticide applications. However, whether Bt corn exerts undesirable effects on non-target arthropods (NTAs is still controversial. We conducted a 2-yr study in Shangzhuang Agricultural Experiment Station to assess the potential impact of Bt corn on field population density, biodiversity, community composition and structure of NTAs. On each sampling date, the total abundance, Shannon's diversity index, Pielou's evenness index and Simpson's diversity index were not significantly affected by Bt corn as compared to non-Bt corn. The "sampling dates" had a significant effect on these indices, but no clear tendencies related to "Bt corn" or "sampling dates X corn variety" interaction were recorded. Principal response curve analysis of variance indicated that Bt corn did not alter the distribution of NTAs communities. Bray-Curtis dissimilarity and distance analysis showed that Cry1Ac toxin exposure did not increase community dissimilarities between Bt and non-Bt corn plots and that the evolution of non-target arthropod community was similar on the two corn varieties. The cultivation of Bt corn failed to show any detrimental evidence on the density of non-target herbivores, predators and parasitoids. The composition of herbivores, predators and parasitoids was identical in Bt and non-Bt corn plots. Taken together, results from the present work support that Bt corn producing Cry1Ac toxins does not adversely affect NTAs.

  16. Depletion of alveolar macrophages in CD11c diphtheria toxin receptor mice produces an inflammatory response

    Science.gov (United States)

    Roberts, Lydia M; Ledvina, Hannah E; Tuladhar, Shraddha; Rana, Deepa; Steele, Shaun P; Sempowski, Gregory D; Frelinger, Jeffrey A

    2015-01-01

    Alveolar macrophages play a critical role in initiating the immune response to inhaled pathogens and have been shown to be the first cell type infected following intranasal inoculation with several pathogens, including Francisella tularensis. In an attempt to further dissect the role of alveolar macrophages in the immune response to Francisella, we selectively depleted alveolar macrophages using CD11c.DOG mice. CD11c.DOG mice express the diphtheria toxin receptor (DTR) under control of the full CD11c promoter. Because mice do not express DTR, tissue restricted expression of the primate DTR followed by treatment with diphtheria toxin (DT) has been widely used as a tool in immunology to examine the effect of acute depletion of a specific immune subset following normal development. We successfully depleted alveolar macrophages via intranasal administration of DT. However, alveolar macrophage depletion was accompanied by many other changes to the cellular composition and cytokine/chemokine milieu in the lung that potentially impact innate and adaptive immune responses. Importantly, we observed a transient influx of neutrophils in the lung and spleen. Our experience serves as a cautionary note to other researchers using DTR mice given the complex changes that occur following DT treatment that must be taken into account when analyzing data. PMID:26029367

  17. Whole genome sequencing of diverse Shiga toxin-producing and non-producing Escherichia coli strains reveals a variety of virulence and novel antibiotic resistance plasmids.

    Science.gov (United States)

    Losada, Liliana; DebRoy, Chitrita; Radune, Diana; Kim, Maria; Sanka, Ravi; Brinkac, Lauren; Kariyawasam, Subhashinie; Shelton, Daniel; Fratamico, Pina M; Kapur, Vivek; Feng, Peter C H

    2016-01-01

    The genomes of a diverse set of Escherichia coli, including many Shiga toxin-producing strains of various serotypes were determined. A total of 39 plasmids were identified among these strains, and many carried virulence or putative virulence genes of Shiga toxin-producing E. coli strains, virulence genes for other pathogenic E. coli groups, and some had combinations of these genes. Among the novel plasmids identified were eight that carried resistance genes to aminoglycosides, carbapenems, penicillins, cephalosporins, chloramphenicol, dihydrofolate reductase inhibitors, sulfonamides, tetracyclines and resistance to heavy metals. Two of the plasmids carried six of these resistance genes and two novel IncHI2 plasmids were also identified. The results of this study showed that plasmids carrying diverse resistance and virulence genes of various pathogenic E. coli groups can be found in E. coli strains and serotypes regardless of the isolate's source and therefore, is consistent with the premise that these mobile elements carrying these traits may be broadly disseminated among E. coli. Published by Elsevier Inc.

  18. Virulence gene profiles of Shiga-toxin producing Escherichia coli isolates from retail raw meat in Iran

    Directory of Open Access Journals (Sweden)

    M. Panahee

    2017-03-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC is recognised as toxin producing group of E. coli and one of the most significant foodborne pathogens worldwide. The aim of this study was to detect STEC and determine virulence gene profiles of these pathogens in different kinds of meat and prod-ucts in Iran. For this reason a total of 182 samples of minced beef, mutton, chicken meat, chicken feet and mechanically separated chicken meat were collected from retail markets for detection of STEC by PCR method. Of the 72 E. coli isolated from examined samples, 29 of them were STEC. The highest presence of STEC was detected in minced beef (23.5% followed by chicken feet (15%, mutton (13.3%, mechanically separated chicken meat (12.5% and chicken meat (5.5% respectively. In addition the results of PCR assay indicated that 21 (72.4% and 4 (13.7% of isolates carried stx2 and eaeA genes respectively. However, according to the results stx2 was the most prevalent gene detected in all kinds of examined samples. Our findings showed that evaluation of the prevalence and viru-lence factors of this pathogen seems necessary considering the increasing importance of STEC as one of the most significant foodborne pathogens.

  19. Survey on the occurrence of shiga toxin producing strains of Escherichia coli (STEC) in drinking water from central Hessia

    Energy Technology Data Exchange (ETDEWEB)

    Stelz, A.; Zschoeck, M. [Untersuchungsamt Hessen, Giessen (Germany); Fels, K.; Alter, E. [Fachhochschule Giessen-Friedberg, Giessen (Germany)

    2001-07-01

    Consumption of unheated bovine food is said to be the main cause of outbreaks of enterohemorrhagic colitis (EC) and hemolytic syndrome (HUS) by E. coli O157 in man. Some cases were attributed to the ingestion of contaminated drinking water. Certain types of resources for drinking water supply are at risk of contamination with cattle faeces or sewage. In routine drinking water control E. coli is an index organism and must not be found in a sample of 100 ml. We investigated a total of 1700 drinking water samples from central Hessia (Germany) for shiga toxin producing strains of E. coli (STEC). A developed sensitive investigation scheme made it possible to detect up to 10 STEC per 100 ml water sample at least. ELISA was used for detection of shiga toxins 1 and 2, m-PCR for the genes encoding stx1, stx2, EHEC-hlyA and eaeA, plating on Enterohemolysin agar for detection of the enterohemolysin phenotype and slide agglutination technique for confirming E. coli O157. In 108 out of 1700 drinking water samples E. coli was detected, but none of the isolates belonged to serotype O157. ST1 and ST2 were not produced by the isolates. Thus, under normal circumstances drinking water in central Hessia seems to be no vehicle for STEC. (orig.)

  20. Screening for the presence of mcr-1/mcr-2 genes in Shiga toxin-producing Escherichia coli recovered from a major produce-production region in California

    Science.gov (United States)

    Mavrici, Daniela; Yambao, Jaszemyn C.; Lee, Bertram G.; Quiñones, Beatriz; He, Xiaohua

    2017-01-01

    The rapid spreading of polymyxin E (colistin) resistance among bacterial strains through the horizontally transmissible mcr-1 and mcr-2 plasmids has become a serious concern. The emergence of these genes in Shiga toxin-producing Escherichia coli (STEC), a group of human pathogenic bacteria was even more worrisome, urging us to investigate the prevalence of mcr genes among STEC isolates. A total of 1000 STEC isolates, recovered from livestock, wildlife, produce and other environmental sources in a major production region for leafy vegetables in California during 2006–2014, were screened by PCR for the presence of plasmid-borne mcr-1 and mcr-2. All isolates tested yielded negative results, indicating if any, the occurrence rate of mcr-1/mcr-2 among STEC was very low in this agricultural region. This study provides valuable information such as sample size needed and methodologies for future surveillance programs of antimicrobial resistance. PMID:29117270

  1. Molecular characterization and phylogeny of Shiga toxin-producing E. coli (STEC) from imported beef meat in Malaysia.

    Science.gov (United States)

    Abuelhassan, Nawal Nouridaim; Mutalib, Sahilah Abdul; Gimba, Fufa Ido; Yusoff, Wan Mohtar

    2016-09-01

    This study aimed at determining the presence and characterization of Escherichia coli and Shiga toxin-producing E. coli (STEC) from imported frozen beef meats. Seventy-four (74) frozen imported beef meat samples from two countries, India (42 samples) and Australia (32 samples), were collected and tested for E. coli. These samples were purchased from the frozen meat sections of five different supermarkets in different locations in Selangor, Malaysia, from April 2012 to October 2014. A total of 222 E. coli strains were isolated from the meat samples; 126 strains were isolated from country A (India), and 96 E. coli strains were from country of origin B (Australia), respectively. A total of 70 E. coli strains were identified and characterized. All E. coli strains were isolated into Fluorocult medium and identified using API 20E kit. All selected E. coli strains were characterized for Shiga toxin genes (stx1 and stx2). All biochemically identified E. coli in this study were further subjected to molecular detection through polymerase chain reaction (PCR) amplification and characterization using 16S ribosomal RNA (rRNA) gene of Shiga toxin-producing E. coli. Of the 70 E. coli strains, 11 strains were positive for both Shiga toxin genes (stx1 and stx2) and 11 (11/70) strains were positive for stx1 gene, while 25 (25/70) strains were positive for stx2 gene. The analysis of 16S rRNA gene of all the E. coli isolates in this study was successfully sequenced and analyzed, and based on sequence data obtained, a phylogenetic tree of the 16S rRNA gene was performed using Clustal W programme in MEGA 6.06 software. Phylogenetic tree showed that the E. coli isolates in our study cluster with the strain of E. coli isolated in other countries, which further confirm that the isolates of E. coli in this study are similar to those obtained in other studies. As a result, all the strains obtained in this study proved to be a strain of pathogenic E. coli, which may cause a serious outbreak

  2. N-chlorotaurine, a long-lived oxidant produced by human leukocytes, inactivates Shiga toxin of enterohemorrhagic Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Christian Eitzinger

    Full Text Available N-chlorotaurine (NCT, the main representative of long-lived oxidants produced by granulocytes and monocytes, is known to exert broad-spectrum microbicidal activity. Here we show that NCT directly inactivates Shiga toxin 2 (Stx2, used as a model toxin secreted by enterohemorrhagic Escherichia coli (EHEC. Bacterial growth and Stx2 production were both inhibited by 2 mM NCT. The cytotoxic effect of Stx2 on Vero cells was removed by ≥5.5 mM NCT. Confocal microscopy and FACS analyses showed that the binding of Stx2 to human kidney glomerular endothelial cells was inhibited, and no NCT-treated Stx2 entered the cytosol. Mass spectrometry displayed oxidation of thio groups and aromatic amino acids of Stx2 by NCT. Therefore, long-lived oxidants may act as powerful tools of innate immunity against soluble virulence factors of pathogens. Moreover, inactivation of virulence factors may contribute to therapeutic success of NCT and novel analogs, which are in development as topical antiinfectives.

  3. Hybrid microarray based on double biomolecular markers of DNA and carbohydrate for simultaneous genotypic and phenotypic detection of cholera toxin-producing Vibrio cholerae.

    Science.gov (United States)

    Shin, Hwa Hui; Seo, Jeong Hyun; Kim, Chang Sup; Hwang, Byeong Hee; Cha, Hyung Joon

    2016-05-15

    Life-threatening diarrheal cholera is usually caused by water or food contaminated with cholera toxin-producing Vibrio cholerae. For the prevention and surveillance of cholera, it is crucial to rapidly and precisely detect and identify the etiological causes, such as V. cholerae and/or its toxin. In the present work, we propose the use of a hybrid double biomolecular marker (DBM) microarray containing 16S rRNA-based DNA capture probe to genotypically identify V. cholerae and GM1 pentasaccharide capture probe to phenotypically detect cholera toxin. We employed a simple sample preparation method to directly obtain genomic DNA and secreted cholera toxin as target materials from bacterial cells. By utilizing the constructed DBM microarray and prepared samples, V. cholerae and cholera toxin were detected successfully, selectively, and simultaneously; the DBM microarray was able to analyze the pathogenicity of the identified V. cholerae regardless of whether the bacteria produces toxin. Therefore, our proposed DBM microarray is a new effective platform for identifying bacteria and analyzing bacterial pathogenicity simultaneously. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Antibiotic Susceptibility, Genetic Diversity, and the Presence of Toxin Producing Genes in Campylobacter Isolates from Poultry

    Directory of Open Access Journals (Sweden)

    Jeeyeon Lee

    2017-11-01

    Full Text Available This study examined antibiotic susceptibility, genetic diversity, and characteristics of virulence genes in Campylobacter isolates from poultry. Chicken (n = 152 and duck (n = 154 samples were collected from 18 wet markets in Korea. Campylobacter spp. isolated from the carcasses were identified by PCR. The isolated colonies were analyzed for antibiotic susceptibility to chloramphenicol, amikacin, erythromycin, tetracycline, ciprofloxacin, nalidixic acid, and enrofloxacin. The isolates were also used to analyze genetic diversity using the DiversiLabTM system and were tested for the presence of cytolethal distending toxin (cdt genes. Campylobacter spp. were isolated from 45 poultry samples out of 306 poultry samples (14.7% and the average levels of Campylobacter contamination were 22.0 CFU/g and 366.1 CFU/g in chicken and duck samples, respectively. Moreover, more than 90% of the isolates showed resistance to nalidixic acid and ciprofloxacin. Genetic correlation analysis showed greater than 95% similarity between 84.4% of the isolates, and three cdt genes (cdtA, cdtB, and cdtC were present in 71.1% of Campylobacter isolates. These results indicate that Campylobacter contamination should be decreased to prevent and treat Campylobacter foodborne illness.

  5. Effect of carvacrol on O157 and non-O157 Shiga toxin producing Escherichia coli

    Directory of Open Access Journals (Sweden)

    Alexandros Stratakos

    2017-06-01

    Full Text Available Shiga toxin Escherichia coli (STEC strains are important foodborne bacteria linked to diarrhea, enteritis, hemolytic-uremic syndrome and in some cases death. E. coli O157:H7 is the most common strain amongst STECs however non-O157 STECs have been connected with several outbreaks on an international level.  The use of natural plant extracts to reduce the risk from foodborne pathogens is gaining increasing importance. Therefore in this study, we tested the antibacterial effect of carvacrol, a major component of oregano essential oil, on E. coli serogroups O157, O26, O45, O103, O111, O121, O145 as well as serogroup O104 responsible for the massive outbreak in Germany in 2011. Carvacrol showed antibacterial effect on all strains tested. The relative electric conductivity was assessed in order to investigate the changes in membrane permeability and thus to investigate the antimicrobial mechanism of carvacrol. Results showed that the relative conductivity increased with increasing concentrations of carvacrol which showed that there was an increasing leakage of electrolytes due to disruption of the cell membrane. The data presented here revealed that carvacrol has the potential to be used as a natural antimicrobial against STECs.

  6. Prevalence and Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Slaughtered Qurban Animal in Jakarta Province

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    Siti Gusti Ningrum

    2016-08-01

    Full Text Available This study was conducted to investigate the presence of shiga toxin producing Escherichia coli (STEC and the possibility of carrying rfbE gene and H7 flagellar on meat, liver, and stool samples collected from Jakarta Province of Indonesia. A total of 51 samples collected from meat, liver, and stool of slaughtered cattle from qurban festival were tested using conventional culture and multiplex PCR methods. STEC non O157 were detected in meat (5.3% and stool (8.3% with one isolate from stool carried H7 flagellar. However, all isolates were lacking of rfbE gene. In antimicrobial susceptibility tests, the STEC isolates showed antibiotic resistance to erythromycin and oxacillin. Overall, the result shows that meat and liver of this origin activity represents a potential risk to human health.

  7. Isolation and Characterization of a Double Stranded DNA Megavirus Infecting the Toxin-Producing Haptophyte Prymnesium parvum

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    Ben A. Wagstaff

    2017-03-01

    Full Text Available Prymnesium parvum is a toxin-producing haptophyte that causes harmful algal blooms globally, leading to large-scale fish kills that have severe ecological and economic implications. For the model haptophyte, Emiliania huxleyi, it has been shown that large dsDNA viruses play an important role in regulating blooms and therefore biogeochemical cycling, but much less work has been done looking at viruses that infect P. parvum, or the role that these viruses may play in regulating harmful algal blooms. In this study, we report the isolation and characterization of a lytic nucleo-cytoplasmic large DNA virus (NCLDV collected from the site of a harmful P. parvum bloom. In subsequent experiments, this virus was shown to infect cultures of Prymnesium sp. and showed phylogenetic similarity to the extended Megaviridae family of algal viruses.

  8. Assessment of Shiga Toxin-Producing Escherichia coli O157 Illnesses Prevented by Recalls of Beef Products.

    Science.gov (United States)

    Seys, Scott A; Sampedro, Fernando; Hedberg, Craig W

    2015-09-01

    Beef product recall data from 2005 through 2012 associated with Shiga toxin-producing Escherichia coli (STEC) O157 contamination were used to develop quantitative models to estimate the number of illnesses prevented by recalls. The number of illnesses prevented was based on the number of illnesses that occurred relative to the number of pounds consumed, then extrapolated to the number of pounds of recalled product recovered. A simulation using a Program Evaluation and Review Technique (PERT) probability distribution with illness-related recalls estimated 204 (95% credible interval, 117-333) prevented STEC O157 illnesses from 2005 through 2012. Recalls not associated with illnesses had more recalled product recovered and prevented an estimated 83 additional STEC O157 illnesses. Accounting for underdiagnosis resulted in an estimated total of 7500 STEC O157 illnesses prevented over 8 years. This study demonstrates that recalls, although reactive in nature, are an important tool for averting further exposure and illnesses.

  9. Leukotriene C4 increases the susceptibility of adult mice to Shiga toxin-producing Escherichia coli infection.

    Science.gov (United States)

    Cabrera, Gabriel; Fernández-Brando, Romina J; Mejías, María Pilar; Ramos, María Victoria; Abrey-Recalde, María Jimena; Vanzulli, Silvia; Vermeulen, Mónica; Palermo, Marina S

    2015-12-01

    Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen that causes hemorrhagic colitis. Under some circumstances, Shiga toxin (Stx) produced within the intestinal tract enters the bloodstream, leading to systemic complications that may cause the potentially fatal hemolytic-uremic syndrome (HUS). Despite STEC human infection is characterized by acute inflammation of the colonic mucosa, little is known regarding the role of proinflammatory mediators like cysteine leukotrienes (cysLTs) in this pathology. Thus, the aim of this work was to analyze whether leukotriene C4 (LTC4) influences STEC pathogenesis in mice. We report that exogenous LTC4 pretreatment severely affected the outcome of STEC gastrointestinal infection. LTC4-pretreated (LTC4+) and STEC-infected (STEC+) mice showed an increased intestinal damage by histological studies, and a decreased survival compared to LTC4-non-pretreated (LTC4-) and STEC+ mice. LTC4+/STEC+ mice that died after the infection displayed neutrophilia and high urea levels, indicating that the cause of death was related to Stx2-toxicity. Despite the differences observed in the survival between LTC4+ and LTC4- mice after STEC infection, both groups showed the same survival after Stx2-intravenous inoculation. In addition, LTC4 pretreatment increased the permeability of mucosal intestinal barrier, as assessed by FITC-dextran absorption experiments. Altogether these results suggest that LTC4 detrimental effect on STEC infection is related to the increased passage of pathogenic factors to the bloodstream. Finally, we showed that STEC infection per se increases the endogenous LTC4 levels in the gut, suggesting that this inflammatory mediator plays a role in the pathogenicity of STEC infection in mice, mainly by disrupting the mucosal epithelial barrier. Copyright © 2015 Elsevier GmbH. All rights reserved.

  10. Characteristics of Shiga toxin-producing Escherichia coli from meat and milk products of different origins and association with food producing animals as main contamination sources.

    Science.gov (United States)

    Martin, Annett; Beutin, Lothar

    2011-03-15

    Shiga toxin-producing strains of Escherichia coli (STEC) cause diarrhoea and haemorrhagic colitis in humans. Most human infections are attributed to consumption of STEC contaminated foodstuff. Food producing animals constitute important reservoirs of STEC and serve as source of food contamination. In this study, we have analyzed 593 foodborne STEC strains for their serotypes and for nine virulence genes (stx1, stx1c, stx1d, stx2, stx2b, stx2e, stx2g, E-hly and eae). The 593 STEC strains grouped into 215 serotypes, and 123 serotypes (57.2%) were represented each by only one STEC isolate. Fifteen serotypes (7.0%) were attributed to 198 (33.3%) of the 593 STEC strains. The foodborne STEC were grouped into different categories in relation to the species of the food producing animal (cattle, pigs, sheep, goats, red deer, wild-boar and hare). Univariate and multivariate statistical analyses revealed significant similarities between the animal origin of the food and the virulence markers of foodborne STEC. Significant associations (pfood producing animals. Virulence profiles and serotypes of STEC from food showed remarkable similarities to those of faecal STEC that were from the same animal species. The findings from our study clearly indicate that the food producing animals represent the most important source for the entry of STEC in the food chain. Sound hygiene measures implemented at critical stages of food production (milking, slaughtering, and evisceration) should be most effective in reducing the frequency of STEC contamination of food derived from domestic and wildlife animals. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Incidence of Shiga toxin-producing Escherichia coli strains in beef, pork, chicken, deer, boar, bison, and rabbit retail meat.

    Science.gov (United States)

    Magwedere, Kudakwashe; Dang, Huu Anh; Mills, Edward W; Cutter, Catherine N; Roberts, Elisabeth L; DeBroy, Chitrita

    2013-03-01

    The objective of the current study was to determine the incidence of contamination by the top 7 Shiga toxin-producing Escherichia coli (STEC) O-groups, responsible for the majority of E. coli infections in human beings, in retail meat from different animal species. Samples from ground beef (n = 51), ground pork (n = 16), ground chicken (n = 16), and game meat (deer, wild boar, bison, and rabbit; n = 55) were collected from retail vendors for the detection of 7 STEC O-groups (O26, O45, O103, O111, O121, O145, and O157). Meat samples were tested by using a multiplex polymerase chain reaction assay targeting the wzx gene of O antigen gene clusters of the 7 STEC O-groups. The positive samples were further tested for Shiga toxin genes (stx1 and stx2). Out of a total of 83 ground beef, pork, and chicken samples, 17 (20%) carried O121, 9 (10%) carried O45, 8 (9%) carried O157, 3 (3%) carried O103, and 1 (1%) carried O145. None of the samples were positive for O26, O111, or the stx gene. All 3 white-tailed deer samples (100%) were positive for O45, O103, or both, 2 (10%) out of 20 red deer samples exhibited the presence of O103, and all 3 bison samples were contaminated with either O121, O145, or O157. One sample from ground deer, contaminated with E. coli O45, carried the stx1 gene. This preliminary investigation illustrates the importance of microbiological testing of pathogens in meat products, as well as the recognized need for increased surveillance and research on foodborne pathogens.

  12. Proteomic View of Interactions of Shiga Toxin-Producing Escherichia coli with the Intestinal Environment in Gnotobiotic Piglets.

    Science.gov (United States)

    Pieper, Rembert; Zhang, Quanshun; Clark, David J; Parmar, Prashanth P; Alami, Hamid; Suh, Moo-Jin; Kuntumalla, Srilatha; Braisted, John C; Huang, Shih-Ting; Tzipori, Saul

    2013-01-01

    Shiga toxin (Stx)-producing Escherichia coli cause severe intestinal infections involving colonization of epithelial Peyer's patches and formation of attachment/effacement (A/E) lesions. These lesions trigger leukocyte infiltration followed by inflammation and intestinal hemorrhage. Systems biology, which explores the crosstalk of Stx-producing Escherichia coli with the in vivo host environment, may elucidate novel molecular pathogenesis aspects. Enterohemorrhagic E. coli strain 86-24 produces Shiga toxin-2 and belongs to the serotype O157:H7. Bacterial cells were scrapped from stationary phase cultures (the in vitro condition) and used to infect gnotobiotic piglets via intestinal lavage. Bacterial cells isolated from the piglets' guts constituted the in vivo condition. Cell lysates were subjected to quantitative 2D gel and shotgun proteomic analyses, revealing metabolic shifts towards anaerobic energy generation, changes in carbon utilization, phosphate and ammonia starvation, and high activity of a glutamate decarboxylase acid resistance system in vivo. Increased abundance of pyridine nucleotide transhydrogenase (PntA and PntB) suggested in vivo shortage of intracellular NADPH. Abundance changes of proteins implicated in lipopolysaccharide biosynthesis (LpxC, ArnA, the predicted acyltransferase L7029) and outer membrane (OM) assembly (LptD, MlaA, MlaC) suggested bacterial cell surface modulation in response to activated host defenses. Indeed, there was evidence for interactions of innate immunity-associated proteins secreted into the intestines (GP340, REG3-γ, resistin, lithostathine, and trefoil factor 3) with the bacterial cell envelope. Proteomic analysis afforded insights into system-wide adaptations of strain 86-24 to a hostile intestinal milieu, including responses to limited nutrients and cofactor supplies, intracellular acidification, and reactive nitrogen and oxygen species-mediated stress. Protein and lipopolysaccharide compositions of the OM were

  13. Proteomic View of Interactions of Shiga Toxin-Producing Escherichia coli with the Intestinal Environment in Gnotobiotic Piglets.

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    Rembert Pieper

    Full Text Available Shiga toxin (Stx-producing Escherichia coli cause severe intestinal infections involving colonization of epithelial Peyer's patches and formation of attachment/effacement (A/E lesions. These lesions trigger leukocyte infiltration followed by inflammation and intestinal hemorrhage. Systems biology, which explores the crosstalk of Stx-producing Escherichia coli with the in vivo host environment, may elucidate novel molecular pathogenesis aspects.Enterohemorrhagic E. coli strain 86-24 produces Shiga toxin-2 and belongs to the serotype O157:H7. Bacterial cells were scrapped from stationary phase cultures (the in vitro condition and used to infect gnotobiotic piglets via intestinal lavage. Bacterial cells isolated from the piglets' guts constituted the in vivo condition. Cell lysates were subjected to quantitative 2D gel and shotgun proteomic analyses, revealing metabolic shifts towards anaerobic energy generation, changes in carbon utilization, phosphate and ammonia starvation, and high activity of a glutamate decarboxylase acid resistance system in vivo. Increased abundance of pyridine nucleotide transhydrogenase (PntA and PntB suggested in vivo shortage of intracellular NADPH. Abundance changes of proteins implicated in lipopolysaccharide biosynthesis (LpxC, ArnA, the predicted acyltransferase L7029 and outer membrane (OM assembly (LptD, MlaA, MlaC suggested bacterial cell surface modulation in response to activated host defenses. Indeed, there was evidence for interactions of innate immunity-associated proteins secreted into the intestines (GP340, REG3-γ, resistin, lithostathine, and trefoil factor 3 with the bacterial cell envelope.Proteomic analysis afforded insights into system-wide adaptations of strain 86-24 to a hostile intestinal milieu, including responses to limited nutrients and cofactor supplies, intracellular acidification, and reactive nitrogen and oxygen species-mediated stress. Protein and lipopolysaccharide compositions of the OM

  14. Molecular identification of Aspergillus and Eurotium species isolated from rice and their toxin-producing ability.

    Science.gov (United States)

    Yazdani, D; Zainal Abidin, M A; Tan, Y H; Kamaruzaman, S

    2011-01-01

    Thirty milled rice samples were collected from retailers in 4 provinces of Malaysia. These samples were evaluated for Aspergillus spp. infection by direct plating on malt extract salt agar (MESA). All Aspergillus holomorphs were isolated and identified using nucleotide sequences of ITS 1 and ITS 2 of rDNA. Five anamorphs (Aspergillus flavus, A. oryzae, A. tamarii, A. fumigatus and A. niger) and 5 teleomorphs (Eurotium rubrum, E. amstelodami, E. chevalieri, E. cristatum and E. tonophilum) were identified. The PCR-sequencing based technique for sequences of ITS 1 and ITS 2 is a fast technique for identification of Aspergillus and Eurotium species, although it doesn't work flawlessly for differentiation of Eurotium species. All Aspergillus and Eurotium isolates were screened for their ability to produce aflatoxin and ochratoxin A (OTA) by HPLC and TLC techniques. Only A. flavus isolate UPM 89 was able to produce aflatoxins B1 and B2.

  15. Prevalence of Shiga Toxin-Producing and Enteropathogenic Escherichia coli in Wild and Pet Birds in Iran

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    A Koochakzadeh

    2015-12-01

    Full Text Available ABSTRACT The aim of this study was to investigate the prevalence of Shiga toxin-producing Escherichia coli (STEC and enteropathogenic E. coli (EPEC strains and to identify the stx gene types in wild captive and companion birds. In total,657 E. coli isolates from 219 birds belonging to 38 different species were investigated for the presence of STEC and EPEC strains. It was shown that five birds (2.28% carried strains positive for one or more of the virulence factors investigated. The results indicated that 1.8% (n=4 and 0.45% (n=1 of the birds carried STEC and EPEC strains, respectively. All STEC strains harbored the stx2f and eae genes and this finding reveals the role of other birds, in addition to pigeons, as reservoirs of STEC. The only EPEC strain in this study was isolated from a Myna. Based on our knowledge, this is the first report of Stx2f-producing STEC in Geese, Duck and Lesser kestrel. In conclusion, the results indicate a low frequency of STEC carriage in wild and companion birds, and point out the need of additionally screening for the presence of stx2f in all the eae-harboring strains from birds.

  16. Real-time genomic investigation underlying the public health response to a Shiga toxin-producing Escherichia coli O26:H11 outbreak in a nursery

    NARCIS (Netherlands)

    Moran-Gilad, J; Rokney, A; Danino, D; Ferdous, M; Alsana, F; Baum, M; Dukhan, L; Agmon, V; Anuka, E; Valinsky, L; Yishay, R; Grotto, I; Rossen, J W A; Gdalevich, M

    2017-01-01

    Shiga toxin-producing Escherichia coli (STEC) is a significant cause of gastrointestinal infection and the haemolytic-uremic syndrome (HUS). STEC outbreaks are commonly associated with food but animal contact is increasingly being implicated in its transmission. We report an outbreak of STEC

  17. Fusarium dactylidis sp. nov., a novel nivalenol toxin-producing species sister to F. pseudograminearum isolated from orchard grass (Dactylis glomerata) in Oregon and New Zealand

    Science.gov (United States)

    The B trichothecene toxin-producing clade (B clade) of Fusarium includes the etiological agents of Fusarium head blight, crown rot of wheat and barley and stem and ear rot of maize. B clade isolates also have been recovered from several wild and cultivated grasses, including Dactylis glomerata (orch...

  18. Estimating true incidence of O157 and non-O157 Shiga toxin-producing Escherichia coli illness in Germany based on notification data of haemolytic uraemic syndrome

    NARCIS (Netherlands)

    Kuehne, A; Bouwknegt, M; Havelaar, A|info:eu-repo/dai/nl/072306122; Gilsdorf, A; Hoyer, P; Stark, K; Werber, D

    2016-01-01

    Shiga toxin-producing Escherichia coli (STEC) is an important cause of gastroenteritis (GE) and haemolytic uraemic syndrome (HUS). Incidence of STEC illness is largely underestimated in notification data, particularly of serogroups other than O157 ('non-O157'). Using HUS national notification data

  19. Rathayibacter toxicus: how a bacterium hitches a ride on a nematode to invade grass seeds and produce a toxin harmful to livestock

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    Rathayibacter toxicus is a forage grass associated Gram-positive bacterium of major concern to food safety and agriculture. This species is listed by USDA-APHIS as a plant pathogen select agent because it produces a tunicamycin-like toxin that is lethal to livestock and may be vectored by nematode s...

  20. Mathematical modeling and numerical analysis of the growth of Non-O157 shiga toxin-producing Escherichia coli in spinach leaves

    Science.gov (United States)

    This study was conducted to investigate the growth of non-O157 Shiga toxin-producing Escherichia coli (STEC) in spinach leaves and to develop kinetic models to describe the bacterial growth. Six serogroups of non-O157 STEC, including O26, O45, O103, O111, O121, and O145, were used in the growth stu...

  1. Isolation of Shiga toxin-producing Escherichia coli (STEC serotype 091:H21 from a child with diarrhea in Porto Alegre city, RS, Brazil

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    Cantarelli Vlademir

    2000-01-01

    Full Text Available We describe the isolation of one strain of Shiga toxin-producing Escherichia coli O91:H21 from a child with diarrhea in the city of Porto Alegre, RS, Brazil. Considering the pathogenic potential of STEC, these organisms should be looked for more carefully among our population.

  2. A heteromeric Texas coral snake toxin targets acid-sensing ion channels to produce pain.

    Science.gov (United States)

    Bohlen, Christopher J; Chesler, Alexander T; Sharif-Naeini, Reza; Medzihradszky, Katalin F; Zhou, Sharleen; King, David; Sánchez, Elda E; Burlingame, Alma L; Basbaum, Allan I; Julius, David

    2011-11-16

    Natural products that elicit discomfort or pain represent invaluable tools for probing molecular mechanisms underlying pain sensation. Plant-derived irritants have predominated in this regard, but animal venoms have also evolved to avert predators by targeting neurons and receptors whose activation produces noxious sensations. As such, venoms provide a rich and varied source of small molecule and protein pharmacophores that can be exploited to characterize and manipulate key components of the pain-signalling pathway. With this in mind, here we perform an unbiased in vitro screen to identify snake venoms capable of activating somatosensory neurons. Venom from the Texas coral snake (Micrurus tener tener), whose bite produces intense and unremitting pain, excites a large cohort of sensory neurons. The purified active species (MitTx) consists of a heteromeric complex between Kunitz- and phospholipase-A2-like proteins that together function as a potent, persistent and selective agonist for acid-sensing ion channels (ASICs), showing equal or greater efficacy compared with acidic pH. MitTx is highly selective for the ASIC1 subtype at neutral pH; under more acidic conditions (pH 100-fold) proton-evoked activation of ASIC2a channels. These observations raise the possibility that ASIC channels function as coincidence detectors for extracellular protons and other, as yet unidentified, endogenous factors. Purified MitTx elicits robust pain-related behaviour in mice by activation of ASIC1 channels on capsaicin-sensitive nerve fibres. These findings reveal a mechanism whereby snake venoms produce pain, and highlight an unexpected contribution of ASIC1 channels to nociception. © 2011 Macmillan Publishers Limited. All rights reserved

  3. Life on the outside: role of biofilms in environmental persistence of Shiga-toxin producing Escherichia coli

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    Philippe eVogeleer

    2014-07-01

    Full Text Available Escherichia coli is a heterogeneous species that can be part of the normal flora of humans but also include strains of medical importance. Among pathogenic members, Shiga-toxin producing E. coli (STEC are some of the more prominent pathogenic E. coli within the public sphere. STEC disease outbreaks are typically associated with contaminated beef, contaminated drinking water, and contaminated fresh produce. These water- and food-borne pathogens usually colonize cattle asymptomatically; cows will shed STEC in their feces and the subsequent fecal contamination of the environment and processing plants is a major concern for food and public safety. This is especially important because STEC can survive for prolonged periods of time outside its host in environments such as water, produce, and farm soil. Biofilms are hypothesized to be important for survival in the environment especially on produce, in rivers, and in processing plants. Several factors involved in biofilm formation such as curli, cellulose, poly-N-acetyl glucosamine, and colanic acid are involved in plant colonization and adherence to different surfaces often found in meat processing plants. In food processing plants, contamination of beef carcasses occurs at different stages of processing and this is often caused by the formation of STEC biofilms on the surface of several pieces of equipment associated with slaughtering and processing. Biofilms protect bacteria against several challenges, including biocides used in industrial processes. STEC biofilms are less sensitive than planktonic cells to several chemical sanitizers such as quaternary ammonium compounds, peroxyacetic acid, and chlorine compounds. Increased resistance to sanitizers by STEC growing in a biofilm is likely to be a source of contamination in the processing plant. This review focuses on the role of biofilm formation by STEC as a means of persistence outside their animal host and factors associated with biofilm formation.

  4. Co-infection in children with bloody diarrhea caused by Shiga toxin-producing Escherichia coli: data of the North Italian HUS Network.

    Science.gov (United States)

    Ardissino, Gianluigi; Possenti, Ilaria; Salardi, Stefania; Tel, Francesca; Colombo, Elisa; Testa, Sara; Daprai, Laura; Picicco, Damiano; Colombo, Rosaria Maria; Torresani, Erminio

    2014-08-01

    Hemolytic-uremic syndrome (HUS) is an important cause of acute kidney injury in children often caused by Shiga toxin-producing Escherichia coli (STEC) enterocolitis. In a screening program for STEC infection in children with bloody diarrhea in northern Italy for early diagnosis of HUS, co-infection with Salmonella or Campylobacter was documented in as many as 35.6% of Shiga toxin-positive patients. It is speculated that infection by Salmonella or Campylobacter may increase the risk of STEC enterocolitis and therefore of HUS. The isolation of microorganisms (other then STEC) in HUS should not be necessarily regarded as the etiological agent for the thrombotic microangiopathy.

  5. Nitrogen-gas bubbling during the cultivation of Clostridium tetani produces a higher yield of tetanus toxin for the preparation of its toxoid.

    Science.gov (United States)

    De Luca, M M; Abeiro, H D; Bernagozzi, J A; Basualdo, J A

    1997-01-01

    We investigated the effect of exposing cultures of Clostridium tetani to nitrogen (N2) gas on the recovery of tetanus toxin to be processed for the preparation of its toxoid. N2 was bubbled through nine 10-liter cultures during the growth of the bacteria, while nine parallel control incubations were maintained without bubbling. We found that treatment of the C. tetani anaerobes with an inert gas in this manner during cultivation produced a highly significant increase in the yield of tetanus toxin from them in comparison with the standard procedure.

  6. Shiga toxin-producing Escherichia coli isolated from chicken meat in Iran: serogroups, virulence factors, and antimicrobial resistance properties.

    Science.gov (United States)

    Momtaz, Hassan; Jamshidi, Alireza

    2013-05-01

    The aim of the current study was to determine the virulence factors, serogroups, and antibiotic resistance properties of Shiga toxin-producing Escherichia coli isolated from chicken meat samples. A total of 422 chicken meat samples were collected from 5 townships of Iran. Specimens were immediately transferred to the laboratory in a cooler with an ice pack. Samples were cultured, and the positive culture samples were analyzed by PCR assays. Finally, the antimicrobial susceptibility test was performed using the disk diffusion method in Mueller-Hinton agar. According to the results, out of 422 samples, 146 (34.59%) were confirmed to be E. coli positive and among E. coli-positive samples, 51 (34.93%) and 31 (21.23%) were from attaching and effacing E. coli (AEEC) and enterohemorrhagic E. coli (EHEC) subgroups, respectively. All of the EHEC-positive samples had all stx1, eaeA, and ehly virulence genes, whereas only 5 (9.80%) of AEEC subgroup had all stx1, stx2, and eaeA genes. As the data revealed, O157 was the most prevalent and O111 was the least prevalent strains in the Shiga toxin-producing E. coli (STEC) population. Among STEC strains, sulI and blaSHV had the highest and lowest incidence rate, respectively. There was a high resistance to tetracycline (76.82%), followed by chloramphenicol (73.17%) and nitrofurantoin (63.41%), but there was low resistance to cephalotine (7.31%) antibiotics in isolated strains. Results shows that the PCR technique has a high performance for detection of serogroups, virulence genes, and antibiotic resistance genes in STEC strains. This study is the first prevalence report of detection of virulence genes, serogroups, and antibiotic resistance properties of STEC strains isolated from chicken meat samples in Iran. Based on the results, chicken meat is one of the main sources of STEC strains and its virulence factors in Iran, so an accurate meat inspection would reduce disease outbreaks.

  7. The Accessory Genome of Shiga Toxin-Producing Escherichia coli Defines a Persistent Colonization Type in Cattle.

    Science.gov (United States)

    Barth, Stefanie A; Menge, Christian; Eichhorn, Inga; Semmler, Torsten; Wieler, Lothar H; Pickard, Derek; Belka, Ariane; Berens, Christian; Geue, Lutz

    2016-09-01

    Shiga toxin-producing Escherichia coli (STEC) strains can colonize cattle for several months and may, thus, serve as gene reservoirs for the genesis of highly virulent zoonotic enterohemorrhagic E. coli (EHEC). Attempts to reduce the human risk for acquiring EHEC infections should include strategies to control such STEC strains persisting in cattle. We therefore aimed to identify genetic patterns associated with the STEC colonization type in the bovine host. We included 88 persistent colonizing STEC (STEC(per)) (shedding for ≥4 months) and 74 sporadically colonizing STEC (STEC(spo)) (shedding for ≤2 months) isolates from cattle and 16 bovine STEC isolates with unknown colonization types. Genoserotypes and multilocus sequence types (MLSTs) were determined, and the isolates were probed with a DNA microarray for virulence-associated genes (VAGs). All STEC(per) isolates belonged to only four genoserotypes (O26:H11, O156:H25, O165:H25, O182:H25), which formed three genetic clusters (ST21/396/1705, ST300/688, ST119). In contrast, STEC(spo) isolates were scattered among 28 genoserotypes and 30 MLSTs, with O157:H7 (ST11) and O6:H49 (ST1079) being the most prevalent. The microarray analysis identified 139 unique gene patterns that clustered with the genoserotypes and MLSTs of the strains. While the STEC(per) isolates possessed heterogeneous phylogenetic backgrounds, the accessory genome clustered these isolates together, separating them from the STEC(spo) isolates. Given the vast genetic heterogeneity of bovine STEC strains, defining the genetic patterns distinguishing STEC(per) from STEC(spo) isolates will facilitate the targeted design of new intervention strategies to counteract these zoonotic pathogens at the farm level. Ruminants, especially cattle, are sources of food-borne infections by Shiga toxin-producing Escherichia coli (STEC) in humans. Some STEC strains persist in cattle for longer periods of time, while others are detected only sporadically. Persisting

  8. A new mouse model for renal lesions produced by intravenous injection of diphtheria toxin A-chain expression plasmid

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    Nakamura Shingo

    2004-04-01

    Full Text Available Abstract Background Various animal models of renal failure have been produced and used to investigate mechanisms underlying renal disease and develop therapeutic drugs. Most methods available to produce such models appear to involve subtotal nephrectomy or intravenous administration of antibodies raised against basement membrane of glomeruli. In this study, we developed a novel method to produce mouse models of renal failure by intravenous injection of a plasmid carrying a toxic gene such as diphtheria toxin A-chain (DT-A gene. DT-A is known to kill cells by inhibiting protein synthesis. Methods An expression plasmid carrying the cytomegalovirus enhancer/chicken β-actin promoter linked to a DT-A gene was mixed with lipid (FuGENE™6 and the resulting complexes were intravenously injected into adult male B6C3F1 mice every day for up to 6 days. After final injection, the kidneys of these mice were sampled on day 4 and weeks 3 and 5. Results H-E staining of the kidney specimens sampled on day 4 revealed remarkable alterations in glomerular compartments, as exemplified by mesangial cell proliferation and formation of extensive deposits in glomerular basement membrane. At weeks 3 and 5, gradual recovery of these tissues was observed. These mice exhibited proteinuria and disease resembling sub-acute glomerulonephritis. Conclusions Repeated intravenous injections of DT-A expression plasmid DNA/lipid complex caused temporary abnormalities mainly in glomeruli of mouse kidney. The disease in these mice resembles sub-acute glomerulonephritis. These DT-A gene-incorporated mice will be useful as animal models in the fields of nephrology and regenerative medicine.

  9. Effect of high pressure treatment on the survival of Shiga toxin-producing Escherichia coli in strawberry puree.

    Science.gov (United States)

    Hsu, HsinYun; Sheen, Shiowshuh; Sites, Joseph; Huang, Lihan; Wu, James Swi-Bea

    2014-06-01

    Most fresh produce, such as strawberries, receives minimal processing and is often eaten raw. Contamination of produce with pathogenic bacteria may occur during growth, harvest, processing, transportation, and storage (abuse temperature) and presents a serious public health risk. Strawberries have been implicated in an outbreak of Escherichia coli O157:H7 infection that sickened 15 people, including one death. Strawberries may also be contaminated by other serogroups of non-O157 Shiga toxin-producing E. coli (STEC), including O26, O45, O103, O111, O121 and O145, which have become known as the "Big Six" or "Top Six" non-O157 STECs. The objective of this research was to explore the potential application of high pressure processing (HPP) treatment to reduce or eliminate STECs in fresh strawberry puree (FSP). FSP, inoculated with a six-strain cocktail of the "Big Six" non-O157 STEC strains or a five-strain cocktail of E. coli O157:H7 in vacuum-sealed packages, were pressure-treated at 150, 250, 350, 450, 550, and 650 MPa (1 MPa = 10(6) N/m(2)) for 5, 15, and 30 min. HPP treatment, at 350 MPa for ≥5 min, significantly reduced STECs in FSP by about 6-log CFU/g from the initial cell population of ca. 8-log CFU/g. Cell rupture, observed by scanning electron microscopy (SEM), demonstrated that the HPP treatments can be potentially used to control both non-O157 and O157:H7 STECs in heat sensitive products. Published by Elsevier Ltd.

  10. Proteomic evidences for rex regulation of metabolism in toxin-producing Bacillus cereus ATCC 14579.

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    Sabrina Laouami

    Full Text Available The facultative anaerobe, Bacillus cereus, causes diarrheal diseases in humans. Its ability to deal with oxygen availability is recognized to be critical for pathogenesis. The B. cereus genome comprises a gene encoding a protein with high similarities to the redox regulator, Rex, which is a central regulator of anaerobic metabolism in Bacillus subtilis and other Gram-positive bacteria. Here, we showed that B. cereus rex is monocistronic and down-regulated in the absence of oxygen. The protein encoded by rex is an authentic Rex transcriptional factor since its DNA binding activity depends on the NADH/NAD+ ratio. Rex deletion compromised the ability of B. cereus to cope with external oxidative stress under anaerobiosis while increasing B. cereus resistance against such stress under aerobiosis. The deletion of rex affects anaerobic fermentative and aerobic respiratory metabolism of B. cereus by decreasing and increasing, respectively, the carbon flux through the NADH-recycling lactate pathway. We compared both the cellular proteome and exoproteome of the wild-type and Δrex cells using a high throughput shotgun label-free quantitation approach and identified proteins that are under control of Rex-mediated regulation. Proteomics data have been deposited to the ProteomeXchange with identifier PXD000886. The data suggest that Rex regulates both the cross-talk between metabolic pathways that produce NADH and NADPH and toxinogenesis, especially in oxic conditions.

  11. Spread and change in stress resistance of Shiga toxin-producing Escherichia coli O157 on fungal colonies.

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    Lee, Ken-Ichi; Kobayashi, Naoki; Watanabe, Maiko; Sugita-Konishi, Yoshiko; Tsubone, Hirokazu; Kumagai, Susumu; Hara-Kudo, Yukiko

    2014-11-01

    To elucidate the effect of fungal hyphae on the behaviour of Shiga toxin-producing Escherichia coli (STEC) O157, the spread and change in stress resistance of the bacterium were evaluated after coculture with 11 species of food-related fungi including fermentation starters. Spread distances of STEC O157 varied depending on the co-cultured fungal species, and the motile bacterial strain spread for longer distances than the non-motile strain. The population of STEC O157 increased when co-cultured on colonies of nine fungal species but decreased on colonies of Emericella nidulans and Aspergillus ochraceus. Confocal scanning microscopy visualization of green fluorescent protein-tagged STEC O157 on fungal hyphae revealed that the bacterium colonized in the water film that existed on and between hyphae. To investigate the physiological changes in STEC O157 caused by co-culturing with fungi, the bacterium was harvested after 7 days of co-culturing and tested for acid resistance. After co-culture with eight fungal species, STEC O157 showed greater acid resistance compared to those cultured without fungi. Our results indicate that fungal hyphae can spread the contamination of STEC O157 and can also enhance the stress resistance of the bacteria. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  12. Risk of haemolytic uraemic syndrome caused by shiga-toxin-producing Escherichia coli infection in adult women in Japan.

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    Fujii, J; Mizoue, T; Kita, T; Kishimoto, H; Joh, K; Nakada, Y; Ugajin, S; Naya, Y; Nakamura, T; Tada, Y; Okabe, N; Maruyama, Y; Saitoh, K; Kurozawa, Y

    2016-04-01

    Shiga-toxin-producing Escherichia coli (STEC) infections usually cause haemolytic uraemic syndrome (HUS) equally in male and female children. This study investigated the localization of globotriaosylceramide (Gb3) in human brain and kidney tissues removed from forensic autopsy cases in Japan. A fatal case was used as a positive control in an outbreak of diarrhoeal disease caused by STEC O157:H7 in a kindergarten in Urawa in 1990. Positive immunodetection of Gb3 was significantly more frequent in female than in male distal and collecting renal tubules. To correlate this finding with a clinical outcome, a retrospective analysis of the predictors of renal failure in the 162 patients of two outbreaks in Japan was performed: one in Tochigi in 2002 and the other in Kagawa Prefecture in 2005. This study concludes renal failure, including HUS, was significantly associated with female sex, and the odds ratio was 4·06 compared to male patients in the two outbreaks. From 2006 to 2009 in Japan, the risk factor of HUS associated with STEC infection was analysed. The number of males and females and the proportion of females who developed HUS were calculated by age and year from 2006 to 2009. In 2006, 2007 and 2009 in adults aged >20 years, adult women were significantly more at risk of developing HUS in Japan.

  13. Identification and molecular characterization of antimicrobial-resistant shiga toxin-producing Escherichia coli isolated from retail meat products.

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    Li, Ming-Cheng; Wang, Fang; Li, Fan

    2011-04-01

    Ten (2.7%) Shiga toxin-producing Escherichia coli (STEC) were isolated from 370 samples of raw minced beef, mutton, pork, and chicken from the Jilin region of China; and additional 10 E. coli O157:H7 isolates were previously isolated from different Jilin regions. Seventeen of the isolates were multiresistant, exhibiting resistance to ampicillin, ciprofloxacin, tetracycline, sulfamethoxazole-trimethoprim, gentamycin, and streptomycin. Class 1 integrons were detected in nine (45.0%) of the STEC isolates and consisted of serogroups O157, O62, O113, O149, and O70. Integrons containing amplicons of a 0.5-1.5 or 1.0 kb gene cassette were found in seven (77.8%) of the integron-containing isolates. Sequencing analysis revealed that these gene cassettes encode genes conferring resistance to trimethoprim (dfrA1) and streptomycin (aadA1). The 0.5 kb cassette described here was found to encode a putative transporter peptide in the STEC. Seventeen isolates contained plasmids with different bands, and transfer by conjugation between strains of E. coli demonstrated that class 1 integrons located on mobile plasmids could contribute to the emergence and dissemination of antimicrobial resistance to ampicillin, gentamycin, streptomycin, and sulfamethoxazole-trimethoprim amongst STEC. These data revealed the high prevalence of antimicrobial-resistant STEC isolates in Jilin's surrounding regions, providing important and useful surveillance information reflecting antimicrobial selection pressure. © Mary Ann Liebert, Inc.

  14. Exposure to the Paralytic Shellfish Toxin Producer Alexandrium catenella Increases the Susceptibility of the Oyster Crassostrea gigas to Pathogenic Vibrios

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    Celina Abi-Khalil

    2016-01-01

    Full Text Available The multifactorial etiology of massive Crassostrea gigas summer mortalities results from complex interactions between oysters, opportunistic pathogens and environmental factors. In a field survey conducted in 2014 in the Mediterranean Thau Lagoon (France, we evidenced that the development of the toxic dinoflagellate Alexandrium catenella, which produces paralytic shellfish toxins (PSTs, was concomitant with the accumulation of PSTs in oyster flesh and the occurrence of C. gigas mortalities. In order to investigate the possible role of toxic algae in this complex disease, we experimentally infected C. gigas oyster juveniles with Vibrio tasmaniensis strain LGP32, a strain associated with oyster summer mortalities, after oysters were exposed to Alexandrium catenella. Exposure of oysters to A. catenella significantly increased the susceptibility of oysters to V. tasmaniensis LGP32. On the contrary, exposure to the non-toxic dinoflagellate Alexandrium tamarense or to the haptophyte Tisochrysis lutea used as a foraging alga did not increase susceptibility to V. tasmaniensis LGP32. This study shows for the first time that A. catenella increases the susceptibility of Crassostrea gigas to pathogenic vibrios. Therefore, in addition to complex environmental factors explaining the mass mortalities of bivalve mollusks, feeding on neurotoxic dinoflagellates should now be considered as an environmental factor that potentially increases the severity of oyster mortality events.

  15. Enteroaggregative Shiga toxin-producing Escherichia coli of serotype O104:H4 in Belgium and Luxembourg

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    K. De Rauw

    2014-09-01

    Full Text Available In 2011, a large outbreak of infections caused by Shiga toxin-producing Escherichia coli (STEC O104:H4 occurred in Germany. This exceptionally virulent strain combined virulence factors of enteroaggregative E. coli (EAggEC and STEC. After the outbreak only a few sporadic cases of infection with this rare serotype were reported, most of which were related to travel to the Middle East or North Africa. Here we describe two cases of enteroaggregative STEC (Agg-STEC O104:H4 infection that occurred in Belgium in 2012 and 2013 respectively. In both cases travel in a Mediterranean country preceded the infection. The first strain was isolated from the stool of a 42-year-old woman presenting bloody diarrhoea, who had travelled to Tunisia the week before. The second case involves a 14-year-old girl who, upon her return from Turkey to Belgium, suffered from an episode of bloody diarrhoea and haemolytic uraemic syndrome. Extended typing of the isolates with pulsed field gel electrophoresis revealed that the strains were closely related, though not exactly the same as the 2011 outbreak strain. This report supports the previously made hypothesis that Agg-STEC has a human reservoir and might be imported by travellers coming from an area where the pathogen is endemic. Furthermore, it emphasizes the concern that these bacteria may cause future outbreaks as evenly virulent O104:H4 isolates seem to be widespread.

  16. Brachyspira (Serpulina) pilosicoli of human origin interfere with the growth of Clostridium perfringens alpha-toxin producer.

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    Calderaro, A; Dettori, G; Ragni, P; Guégan, R; Arcangeletti, M C; Medici, M C; Chezzi, C

    2002-04-01

    Brachyspira (Serpulina) pilosicoli of human origin interfere with the growth of Clostridium perfringens alpha-toxin producer reducing the clostridial growth area and colonies number when bacteria were cultivated together in sheep blood agar plates. The growth inhibition of C. perfringens was only observed when B. (S.) pilosicoli grew 72-96 hours sooner than C. perfringens and after the inoculum of this latter the plates were anaerobically incubated for additional 48 hours. The phenomenon was observed at concentrations of B. (S.) pilosicoli ranging from 10(7) to 10(4) CFU/ml and at concentrations of C. perfringens ranging from 10(7) to 10(1) CFU/ml when the bacteria were 0-10 mm away from each other. When B. (S.) pilosicoli and C. perfringens were inoculated at the same time and when B. (S.) pilosicoli grew 24-48 hours sooner than C. perfringens, the clostridial growth inhibition was not appreciated and only a cooperative haemolysis was observed between the bacteria.

  17. Exposure to the Paralytic Shellfish Toxin Producer Alexandrium catenella Increases the Susceptibility of the Oyster Crassostrea gigas to Pathogenic Vibrios.

    Science.gov (United States)

    Abi-Khalil, Celina; Lopez-Joven, Carmen; Abadie, Eric; Savar, Veronique; Amzil, Zouher; Laabir, Mohamed; Rolland, Jean-Luc

    2016-01-15

    The multifactorial etiology of massive Crassostrea gigas summer mortalities results from complex interactions between oysters, opportunistic pathogens and environmental factors. In a field survey conducted in 2014 in the Mediterranean Thau Lagoon (France), we evidenced that the development of the toxic dinoflagellate Alexandrium catenella, which produces paralytic shellfish toxins (PSTs), was concomitant with the accumulation of PSTs in oyster flesh and the occurrence of C. gigas mortalities. In order to investigate the possible role of toxic algae in this complex disease, we experimentally infected C. gigas oyster juveniles with Vibrio tasmaniensis strain LGP32, a strain associated with oyster summer mortalities, after oysters were exposed to Alexandrium catenella. Exposure of oysters to A. catenella significantly increased the susceptibility of oysters to V. tasmaniensis LGP32. On the contrary, exposure to the non-toxic dinoflagellate Alexandrium tamarense or to the haptophyte Tisochrysis lutea used as a foraging alga did not increase susceptibility to V. tasmaniensis LGP32. This study shows for the first time that A. catenella increases the susceptibility of Crassostrea gigas to pathogenic vibrios. Therefore, in addition to complex environmental factors explaining the mass mortalities of bivalve mollusks, feeding on neurotoxic dinoflagellates should now be considered as an environmental factor that potentially increases the severity of oyster mortality events.

  18. Persistence of Shiga toxin-producing Escherichia coli O26 in various manure-amended soil types.

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    Fremaux, B; Prigent-Combaret, C; Delignette-Muller, M L; Mallen, B; Dothal, M; Gleizal, A; Vernozy-Rozand, C

    2008-01-01

    To evaluate the behaviour of Shiga toxin-producing Escherichia coli (STEC) O26 strains inoculated in manure-amended soils under in vitro conditions. Four green fluorescent protein (GFP)-labelled STEC O26 strains were inoculated in duplicate (at 10(6) CFU g(-1)) in three different manure-amended soil types, including two loam soils (A and B) and one clay loam soil (C), and two incubation temperatures (4 and 20 degrees C) were tested. STEC counts and soil physical parameters were periodically monitored. STEC O26 cells were able to persist during extended periods in soil even in the presence of low moisture levels, i.e. less than 0 x 08 g H2O g(-1) dry soil. At 4 and 20 degrees C, STEC could be detected in soil A for 288 and 196 days, respectively, and in soils B and C for at least 365 days postinoculation at both temperatures. The ambient temperature (i.e. 20 degrees C) was significantly associated with the highest STEC count decline in all soils tested. The temperature and soil properties appear to be contributory factors affecting the long-term survival of STEC O26 in manure-amended soils. This study provides useful information regarding the ecology of STEC O26 in manure-amended soils and may have implications for land and waste management.

  19. Prevalence and molecular characterisation of Shiga toxin-producing Escherichia coli in raw milk cheeses from Lazio region, Italy

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    Selene Marozzi

    2016-02-01

    Full Text Available In recent years, the incidence of foodborne diseases caused by Shiga toxin-producing Escherichia coli (STEC has increased globally. For this reason, within the specific regional control plan for the detection of STEC in food products in Italy, the presence of STEC in unpasteurised milk cheeses was investigated. In total, 203 samples obtained from March 2011 to December 2013 were analysed, with two standard methods (ISO 16654:2001 and ISO 13136:2012. Two strains of E. coli O157 were isolated (2/161, 1.2% but did not carry any virulence-associated genes and 22 stx-positive samples (22/146, 15.1% were detected in enrichment cultures, mostly from ovine cheeses. Only two strains isolated from different ovine cheeses carried stx gene and none of these was eae-positive. This study confirms the presence of stx-positive E. coli and suggests that this type of food cannot be excluded as a potential vehicle of STEC.

  20. The capability of fungi isolated from moldy dwellings to produce toxins

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    Karolina Jeżak

    2016-10-01

    Full Text Available Objectives: The main objective was analysis and assessment of toxinogenic capabilities of fungi isolated from moldy surfaces in residential rooms in an urban agglomeration situated far from flooded areas in moderate climate zone. Material and Methods: The assessment of environmental exposure to mycotoxins was carried out in samples collected from moldy surfaces in form of scrapings and airborne dust from 22 moldy dwellings in winter season. In each sample 2 mycotoxins were analyzed: sterigmatocystin and roquefortine C produced by Aspergillus versicolor and Penicillium chrysogenum, respectively. Mycotoxins were analyzed by high-performance liquid chromatography (HPLC in: scrapings from moldy surfaces, mixture of all species of fungi cultured from scrapings on microbiological medium (malt extract agar, pure cultures of Aspergillus versicolor and Penicillium chrysogenum cultured from scrapings on microbiological medium; mycotoxins in the indoor air dust were also analyzed. Results: The production of sterigmatocystin by individual strains of Aspergillus versicolor cultured on medium was confirmed for 8 of 13 isolated strains ranging 2.1–235.9 μg/g and production of roquefortine C by Penicillium chrysogenum for 4 of 10 strains ranging 12.9–27.6 μg/g. In 11 of 13 samples of the mixture of fungi cultured from scrapings, in which Aspergillus versicolor was found, sterigmatocystin production was at the level of 3.1–1683.2 μg/g, whereas in 3 of 10 samples in which Penicillium chrysogenum occurred, the production of roquefortine C was 0.9–618.9 μg/g. The analysis did not show in any of the tested air dust and scrapings samples the presence of analyzed mycotoxins in the amount exceeding the determination limit. Conclusions: The capability of synthesis of sterigmatocystin by Aspergillus versicolor and roquefortine C by Penicillium chrysogenum growing in mixtures of fungi from scrapings and pure cultures in laboratory conditions was confirmed. The

  1. Prevalence and characterization of Shiga Toxin-producing and enteropathogenic Escherichia coli in shellfish-harvesting areas and their watersheds

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    Balière eCharlotte

    2015-12-01

    Full Text Available During a two-year study, the presence of Shiga-toxin producing E. coli (STEC and enteropathogenic E. coli (EPEC was investigated in shellfish (n=238, seawater (n=12 and surface sediment (n=39 collected from three French coastal shellfish-harvesting areas and freshwaters (n=216 in their watersheds. PCR detection of Shiga toxin- (stx1/stx2 and intimin- (eae genes following enrichment from these samples revealed the presence of least one of the stx genes in 30.3% of shellfish batches, 85.9% of freshwater, 41.7% of seawater, and 28.2% of sediment samples, while the eae gene was observed in 74.8%, 100%, 100%, and 43.6% of shellfish batches, freshwater, seawater, and sediment samples, respectively. Twenty-eight STEC and 89 EPEC strains were isolated and analyzed in order to determine their serotype, phylogroup, and genetic relatedness and to evaluate the presence of the saa and ehxA genes encoding the STEC autoagglutinating adhesin and the enterohemolysin A, respectively. Finally, the ability to form biofilms and antimicrobial susceptibility were investigated for a selection of strains. Eighteen serotypes were identified among the STEC isolates and 57 among the EPEC isolates. A high diversity was observed within these strains, as 79 different PFGE patterns and 48 distinguishable sequence types were identified. Strains were found to belong mainly to phylogroups B1 and B2 and virulence was observed to be low as more than 85% of the strains possessed only stx1, stx2 or eae genes. One STEC and several EPEC strains belonged to three of the five highly pathogenic serogroups (i.e., O26, O103, and O145. The subset of strains tested for their capacity to form biofilms was mainly strongly to moderately adherent and more strains formed a strong biofilm at 18°C than at 30°C. Finally, more than 85% of analyzed strains were found to be sensitive to the 16 tested antibiotics. These data suggest the low risk of human infection by STEC if shellfish from these

  2. The Polymorphic Aggregative Phenotype of Shiga Toxin-Producing Escherichia coli O111 Depends on RpoS and Curli.

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    Diodati, M E; Bates, A H; Miller, W G; Carter, M Q; Zhou, Y; Brandl, M T

    2015-12-28

    Escherichia coli O111 is an emerging non-O157:H7 serotype of Shiga toxin-producing E. coli (STEC). We previously reported that outbreak and environmental, but not sporadic-case, strains of STEC O111 share a distinct aggregation phenotype (M. E. Diodati, A. H. Bates, M. B. Cooley, S. Walker, R. E. Mandrell, and M. T. Brandl, Foodborne Pathog Dis 12:235-243, 2015, http://dx.doi.org/10.1089/fpd.2014.1887). We show here the natural occurrence of nonaggregative variants in single STEC O111 strains. These variants do not produce curli fimbriae and lack RpoS function but synthesize cellulose. The deletion of csgBAC or rpoS in an aggregative outbreak strain abolished aggregate formation, which was rescued when curli biogenesis or RpoS function, respectively, was restored. Complementation of a nonaggregative variant with RpoS also conferred curli production and aggregation. These observations were supported by Western blotting with an anti-CsgA antibody. Immunomicroscopy revealed that curli were undetectable on the cells of the nonaggregative variant and the RpoS mutant but were present in large quantities in the intercellular matrix of the assemblages formed by aggregative strains. Sequence analysis of rpoS in the aggregative strain and its variant showed a single substitution of threonine for asparagine at amino acid 124. Our results indicate that the multicellular behavior of STEC O111 is RpoS dependent via positive regulation of curli production. Aggregation may confer a fitness advantage in O111 outbreak strains under stressful conditions in hydrodynamic environments along the food production chain and in the host, while the occurrence of nonaggregative variants may allow the cell population to adapt to conditions benefiting a planktonic lifestyle. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  3. Detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) in bovine dairy herds in Northern Italy.

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    Trevisani, M; Mancusi, R; Delle Donne, G; Bacci, C; Bassi, L; Bonardi, S

    2014-08-01

    The aim of this study was to monitor the presence of Shiga toxin (Stx)-producing Escherichia coli in dairy farms authorized to sell raw milk and other farms, located in the same area, which sell milk to industry or use it to produce Parmesan or Grana cheese. Our research was focused on the serogroups O157 and O26, which are the most common in human cases in Italy and genetic markers that characterize the strains that can cause hemorrhagic colitis and hemolytic uremic syndrome (EHEC) in humans. Overall, 255 bulk-milk and 225 milk filter samples were screened for the presence of Shiga toxin genes (stx1 and stx2), O157 and O26 serogroups by using PCR. The samples were collected in 193 bovine dairy farms located in Northern Italy, including 32 farms selling raw milk to consumers. According to the preliminary PCR screening test, 32 out of 255 (12.5%; CI95%, 8.7% to 17.3%) bulk milk samples and 68 out of 225 (30.2%; CI95%, 24.3% to 36.7%) milk filters were positive for stx genes. Of the 32 milk samples that were stx-positive, 4 (1.6%, CI95%, 0.4% to 4%) were also positive by PCR for the rfbEO157 gene and 6 (2.4%, CI95%, 0.9% to 5.1%) were positive for the wzxO26 gene. The culture detection method, which was based on the immunomagnetic separation, achieved isolation rates of E. coli serogroups O157 and O26 in 25-67% of the milk samples that tested positive by PCR for these serogroups. STEC O26 was detected in one milk filter (1.6%) from a farm that sells raw milk to consumers directly and one sample (1.4%) of bulk milk intended for pasteurization. The presence of STEC O157 was also detected in 2 milk filters (1.7%) from farms that use milk to produce Grana cheese. All the STEC stains O157 and O26 isolated carried the genes eae and espK and genes belonging to the pathogenicity island OI-122 (efa1/2, sen, pagC), which are markers suitable for screening the human virulent EHEC strains. These virulence markers were also detected in the three strains of stx-negative E. coli O

  4. BOTULINUM TOXIN

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    Nigam, P K; Nigam, Anjana

    2010-01-01

    Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C1, C2, D, E, F and G). All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice. PMID:20418969

  5. Botulinum toxin

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    Nigam P

    2010-01-01

    Full Text Available Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C 1 , C 2 , D, E, F and G. All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice.

  6. Prevalence of Shiga toxin-producing Shigella species isolated from French travellers returning from the Caribbean: an emerging pathogen with international implications.

    Science.gov (United States)

    Gray, M D; Lacher, D W; Leonard, S R; Abbott, J; Zhao, S; Lampel, K A; Prothery, E; Gouali, M; Weill, F-X; Maurelli, A T

    2015-08-01

    Shiga toxins (Stxs) are potent cytotoxins that inhibit host cell protein synthesis, leading to cell death. Classically, these toxins are associated with intestinal infections due to Stx-producing Escherichia coli or Shigella dysenteriae serotype 1, and infections with these strains can lead to haemolytic-uraemic syndrome. Over the past decade, there has been increasing recognition that Stx is produced by additional Shigella species. We recently reported the presence and expression of stx genes in Shigella flexneri 2a clinical isolates. The toxin genes were carried by a new stx-encoding bacteriophage, and infection with these strains correlated with recent travel to Haiti or the Dominican Republic. In this study, we further explored the epidemiological link to this region by utilizing the French National Reference Centre for Escherichia coli, Shigella and Salmonella collection to survey the frequency of Stx-producing Shigella species isolated from French travellers returning from the Caribbean. Approximately 21% of the isolates tested were found to encode and produce Stx. These isolates included strains of S. flexneri 2a, S. flexneri Y, and S. dysenteriae 4. All of the travellers who were infected with Stx-producing Shigella had recently travelled to Haiti, the Dominican Republic, or French Guiana. Furthermore, whole genome sequencing showed that the toxin genes were encoded by a prophage that was highly identical to the phage that we identified in our previous study. These findings demonstrate that this new stx-encoding prophage is circulating within that geographical area, has spread to other continents, and is capable of spreading to multiple Shigella serogroups. Published by Elsevier Ltd.

  7. Conditional Function of Autoaggregative Protein Cah and Common cah Mutations in Shiga Toxin-Producing Escherichia coli.

    Science.gov (United States)

    Carter, Michelle Qiu; Brandl, Maria T; Kudva, Indira T; Katani, Robab; Moreau, Matthew R; Kapur, Vivek

    2017-10-20

    Cah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Although cah is widespread in Shiga toxin-producing Escherichia coli (STEC), we detected mutations in cah at a frequency of 31.3% in this pathogen. In STEC O157:H7 super-shedder strain SS17, a large deletion results in a smaller coding sequence, lacking the C-terminal 71 amino acids compared with Cah in STEC O157:H7 strain EDL933. We examined the function of Cah in biofilm formation and host colonization to better understand selective pressures for cah mutations. EDL933-Cah played a conditional role in biofilm formation in vitro: it enhanced E. coli DH5α biofilm formation on glass surfaces under agitated culture conditions that prevented autoaggregation, but inhibited biofilm formation under hydrostatic conditions that facilitated autoaggregation. This function appeared to be strain-dependent since Cah-mediated biofilm formation was diminished when an EDL933-cah was expressed in SS17. Deletion of cah in EDL933 enhanced bacterial attachment to spinach leaves and altered the adherence pattern of EDL933 to bovine recto-anal junction squamous epithelial (RSE) cells. In contrast, in trans-expression of EDL933-cah in SS17 increased its attachment to leaf surfaces, and in DH5α, enhanced its adherence to RSE cells. Hence the ecological function of Cah appears to be modulated by environmental conditions and other bacterial strain-specific properties. Considering the prevalence of cah in STEC and its role in attachment and biofilm formation, cah mutations might be selected in ecological niches where inactivation of Cah would result in an increased fitness in STEC during colonization of plants or animal hosts.ImportanceShiga toxin-producing Escherichia coli (STEC) harbors genes encoding diverse adhesins and many of these are known to play an important role in bacterial attachment and host colonization. We demonstrated here that the autotransporter protein Cah confers E. coli

  8. Behavior of Different Shiga Toxin-Producing Escherichia coli Serotypes in Various Experimentally Contaminated Raw-Milk Cheeses

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    Miszczycha, Stéphane D.; Perrin, Frédérique; Ganet, Sarah; Jamet, Emmanuel; Tenenhaus-Aziza, Fanny; Montel, Marie-Christine

    2013-01-01

    Shiga toxin-producing Escherichia coli (STEC) is an important cause of food-borne illness. The public health implication of the presence of STEC in dairy products remains unclear. Knowledge of STEC behavior in cheeses would help to evaluate the human health risk. The aim of our study was to observe the growth and survival of experimentally inoculated STEC strains in raw-milk cheeses manufactured and ripened according to five technological schemes: blue-type cheese, uncooked pressed cheese with long ripening and with short ripening steps, cooked cheese, and lactic cheese. Cheeses were contaminated with different STEC serotypes (O157:H7, O26:H11, O103:H2, and O145:H28) at the milk preparation stage. STEC growth and survival were monitored on selective media during the entire manufacturing process. STEC grew (2 to 3 log10 CFU · g−1) in blue-type cheese and the two uncooked pressed cheeses during the first 24 h of cheese making. Then, STEC levels progressively decreased in cheeses that were ripened for more than 6 months. In cooked cheese and in lactic cheese with a long acidic coagulation step (pH cheese and after the coagulation step in the lactic cheese, but STEC was still detectable at the end of ripening and storage. A serotype effect was found: in all cheeses studied, serotype O157:H7 grew less strongly and was less persistent than the others serotypes. This study improves knowledge of the behavior of different STEC serotypes in various raw-milk cheeses. PMID:23087038

  9. Psychiatric symptoms in patients with Shiga toxin-producing E. coli O104:H4 induced haemolytic-uraemic syndrome.

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    Alexandra Kleimann

    Full Text Available In May 2011 an outbreak of Shiga toxin-producing enterohaemorrhagic E. coli (STEC O104:H4 in Northern Germany led to a high number of in-patients, suffering from post-enteritis haemolytic-uraemic syndrome (HUS and often severe affection of the central nervous system. To our knowledge so far only neurological manifestations have been described systematically in literature.To examine psychiatric symptoms over time and search for specific symptom clusters in affected patients.31 in-patients suffering from E. coli O104:H4 associated HUS, were examined and followed up a week during the acute hospital stay. Psychopathology was assessed by clinical interview based on the AMDP Scale, the Brief Symptom Inventory and the Clinical Global Impressions Scale.At baseline mental disorder due to known physiological condition (ICD-10 F06.8 was present in 58% of the examined patients. Patients suffered from various manifestations of cognitive impairment (n = 27 and hallucinations (n = 4. Disturbances of affect (n = 28 included severe panic attacks (n = 9. Psychiatric disorder was significantly associated with higher age (p<0.0001, higher levels of C-reactive protein (p<0.05, and positive family history of heart disease (p<0.05. Even within the acute hospital stay with a median follow up of 7 days, symptoms improved markedly over time (p <0.0001.Aside from severe neurological symptoms the pathology in E.coli O104:H4 associated HUS frequently includes particular psychiatric disturbances. Long term follow up has to clarify whether or not these symptoms subside.

  10. Influence of chlorine substitution on the hydrolytic stability of biaryl ether nucleoside adducts produced by phenolic toxins.

    Science.gov (United States)

    Kuska, Michael S; Majdi Yazdi, Mohadeseh; Witham, Aaron A; Dahlmann, Heidi A; Sturla, Shana J; Wetmore, Stacey D; Manderville, Richard A

    2013-07-19

    A kinetic study is reported for the acid-catalyzed hydrolysis of oxygen (O)-linked biaryl ether 8-2'-deoxyguanosine (dG) adducts produced by phenolic toxins following metabolism into phenoxyl radical intermediates. Strikingly, the reaction rate of hydrolysis at pH 1 decreases as electron-withdrawing chlorine (Cl) substituents are added to the phenoxyl ring. The Hammett plot for hydrolysis at pH 1 shows a linear negative slope with ρX = -0.65, implying that increased Cl-substitution diminishes the rate of hydrolysis by lowering N(7) basicity. Spectrophotometric titration provided an N(7)H(+) pKa value of 1.1 for the unsubstituted adduct 8-phenoxy-dG (Ph-O-dG). Model pyridine compounds suggest N(7)H(+) pKa values of 0.92 and 0.37 for 4-Cl-Ph-O-dG and 2,6-dichloro-Ph-O-dG (DCP-O-dG), respectively. Density functional theory (DFT) calculations also highlight the ability of the 8-phenoxy substituent to lower N(7) basicity and predict a preference for N(3)-protonation for highly chlorinated O-linked 8-dG adducts in water. The calculations also provide a rationale for the hydrolytic reactivity of O-linked 8-dG adducts in the gas-phase, as determined using electrospray mass spectrometry (ESI-MS). The inclusion of our data now establishes that the order of hydrolytic reactivity at neutral pH for bulky 8-dG adducts is N-linked > C-linked > O-linked, which correlates with their relative ease of N(7)-protonation.

  11. Prevalence of Shiga toxin-producing Escherichia coli in food products of animal origin as determined by molecular methods.

    Science.gov (United States)

    Rantsiou, Kalliopi; Alessandria, Valentina; Cocolin, Luca

    2012-03-01

    In this study we report on the prevalence and distribution of Shiga toxin-producing Escherichia coli (STEC) in food products of animal origin, collected in the Piedmont region of Italy, as determined by a combination of quantitative PCR (qPCR) protocols, applied directly to the samples, and of culture-dependent isolation and subsequent molecular identification and characterization of isolates. The qPCR protocols were developed and optimized in this study and targeted the rpoB gene (as a marker for total E. coli) and the stx₁, stx₂ and eaeA genes (as markers for potentially virulent E.coli). They were then used to test for STEC in 101 food samples, before and after enrichment. A STEC prevalence of 42% (21/50) for dairy products and 70% (36/51) for meat products was obtained. A total of 54 STEC isolates were recovered from dairy and meat samples, resulting in a prevalence of 36% and 27% in dairy and meat products, respectively, by the culture method. A large number of strains carried the stx₂ gene (39 out of the 54 STEC strains) compared to strains that carried stx₁ (30 out of 54); only 11 out of 54 strains contained the eaeA gene, while 14 strains contained both stx₁ and stx₂. Eight of the 54 isolates belonged to the O157 serogroup, and none belonged to serogroups O26, O145, O111 or O103. Strains isolated from meat products were diverse, as determined by Enterobacterial repetitive intergenic consensus-PCR (ERIC), while those isolated from dairy products were more similar and grouped together by cluster analysis. The results of the qPCR approach showed a high prevalence of STEC in dairy and meat based products, mainly fermented, indicating a possible safety risk for these types of food commodities. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Characterization of enteropathogenic and Shiga toxin-producing Escherichia coli in cattle and deer in a shared agroecosystem

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    Pallavi eSingh

    2015-04-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC is an important foodborne pathogen. Cattle are suggested to be an important reservoir for STEC; however, these pathogens have also been isolated from other livestock and wildlife. In this study we sought to investigate transmission of STEC, enterohemorrhagic E. coli (EHEC and enteropathogenic E. coli (EPEC between cattle and white-tailed deer in a shared agroecosystem. Cattle feces were collected from 100 animals in a Michigan dairy farm in July 2012, while 163 deer fecal samples were collected during two sampling periods (March and June. The locations of deer fecal pellets were recorded via geographic information system mapping and microsatellite multi-locus genotyping was used to link the fecal samples to individual deer at both time points. Following subculture to sorbitol MacConkey agar and STEC CHROMagar, the pathogens were characterized by serotyping, stx profiling, and PCR-based fingerprinting; multilocus sequence typing (MLST was performed on a subset. STEC and EHEC were cultured from 12% and 16% of cattle, respectively, and EPEC was found in 36%. Deer were significantly less likely to have a pathogen in March versus June where the frequency of STEC, EHEC, and EPEC was 1%, 6% and 22%, respectively. PCR fingerprinting and MLST clustered the cattle- and deer-derived strains together in a phylogenetic tree. Two STEC strains recovered from both animal species shared MLST and fingerprinting profiles, thereby providing evidence of interspecies transmission and highlighting the importance of wildlife species in pathogen shedding dynamics and persistence in the environment and cattle herds.

  13. Influence of selective media on successful detection of Shiga toxin-producing Escherichia coli in food, fecal, and environmental samples.

    Science.gov (United States)

    Hussein, Hussein S; Bollinger, Laurie M

    2008-06-01

    Shiga toxin-producing Escherichia coli (STEC) strains have caused a large number of human illness outbreaks worldwide. In most cases, the infection was traced to consumption of meats or vegetables contaminated with cattle feces. To combat this public health problem, pre- and post-harvest control strategies are continuously implemented to assure food safety. Thus, rapid, reliable, and sensitive methods for STEC detection must be available to provide confidence not only in the meats or vegetables entering the food chain but also in testing humans with illnesses. As a result, enrichment for STEC has been a critical step in any successful protocol for their detection. The base media commonly used for STEC enrichment include sorbitol MacConkey agar, tryptic soy broth (TSB), E. coli broth, enterohemorrhagic E. coli broth, buffered peptone water (BPW), and brain heart infusion broth. In addition to bile salts, antibiotics (e.g., tellurite, cefixime, novobiocin, vancomycin, cefsulodin, and acriflavin) are used at different concentrations to enrich for STEC. In most published reports, however, the reasons for choosing the selective medium were not provided. Thus, this review was intended to evaluate the base media and antibiotics commonly used for STEC detection. The efficacy of a detection method will certainly depend on the choice of the base medium, selective agents, and their concentrations. The interactions among these factors are also expected to affect sensitivity of the detection method, especially when the test sample contains a small number of STEC cells. Because sensitivity of detection is expected to decline when testing for stressed or injured STEC cells, as is the case in environmental samples, a pre-enrichment step in TSB or BPW without antibiotics may be necessary. Future research should focus on identifying possible antibiotic combinations that effectively inhibit most background bacteria without affecting pathogenic STEC strains in the test sample.

  14. Shiga Toxin-Producing Escherichia coli in Plateau Pika (Ochotona curzoniae on the Qinghai-Tibetan Plateau, China

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    Xiangning eBAI

    2016-03-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC are an emerging group of zoonotic pathogens. Ruminants are the natural reservoir of STEC. In this study we determined the prevalence and characteristics of the STEC in plateau pika (Ochotona curzoniae on the Qinghai-Tibetan Plateau, China. A total of 1116 pika samples, including 294 intestinal contents samples, 317 fecal samples, and 505 intestinal contents samples, were collected from May to August in the years 2012, 2013 and 2015, respectively. Twenty-one samples (1.88% yielded at least one STEC isolate; in total, 22 STEC isolates were recovered. Thirteen different O serogroups and 14 serotypes were identified. One stx1 subtype (stx1a and three stx2 subtypes (stx2a, stx2b and stx2d were present in the STEC isolates. Fifteen, fourteen and three STEC isolates harbored the virulence genes ehxA, subA, and astA, respectively. Adherence-associated genes iha and saa were respectively present in 72.73% and 68.18% of the STEC isolates. Twenty antibiotics were active against all the STEC isolates; all strains were resistant to penicillin G, and some to cephalothin or streptomycin. The 22 STEC isolates were divided into 16 PFGE patterns and 12 sequence types. Plateau pikas may play a role in the ongoing circulation of STEC in the Qinghai-Tibetan plateau. This study provides the first report on STEC in plateau pikas and new information about STEC reservoirs in wildlife. Based on the serotypes, virulence gene profiles and MLST analysis, the majority of these pika STECs may pose a low public health risk.

  15. Colonization of Beef Cattle by Shiga Toxin-Producing Escherichia coli during the First Year of Life: A Cohort Study.

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    Raies A Mir

    Full Text Available Each year Shiga toxin-producing Escherichia coli (STEC are responsible for 2.8 million acute illnesses around the world and > 250,000 cases in the US. Lowering the prevalence of this pathogen in animal reservoirs has the potential to reduce STEC outbreaks in humans by controlling its entrance into the food chain. However, factors that modulate the colonization and persistence of STEC in beef cattle remain largely unidentified. This study evaluated if animal physiological factors such as age, breed, sex, and weight gain influenced the shedding of STEC in beef cattle. A cohort of beef calves (n = 260 from a multi-breed beef calf population was sampled every three months after birth to measure prevalence and concentration of STEC during the first year of life. Metagenomic analysis was also used to understand the association between the STEC colonization and the composition of gut microflora. This study identified that beef calves were more likely to shed STEC during the first 6 months and that STEC shedding decreased as the animal matured. Animal breed group, sex of the calf, and average weight gain were not significantly associated with STEC colonization. The metagenomic analysis revealed for the first time that STEC colonization was correlated with a lower diversity of gut microflora, which increases as the cattle matured. Given these findings, intervention strategies that segregate younger animals, more likely to be colonized by STEC from older animals that are ready to be harvested, could be investigated as a method to reduce zoonotic transmission of STEC from cattle to humans.

  16. Characterization of enteropathogenic and Shiga toxin-producing Escherichia coli in cattle and deer in a shared agroecosystem.

    Science.gov (United States)

    Singh, Pallavi; Sha, Qiong; Lacher, David W; Del Valle, Jacquelyn; Mosci, Rebekah E; Moore, Jennifer A; Scribner, Kim T; Manning, Shannon D

    2015-01-01

    Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen. Cattle are suggested to be an important reservoir for STEC; however, these pathogens have also been isolated from other livestock and wildlife. In this study we sought to investigate transmission of STEC, enterohemorrhagic E. coli (EHEC) and enteropathogenic E. coli (EPEC) between cattle and white-tailed deer in a shared agroecosystem. Cattle feces were collected from 100 animals in a Michigan dairy farm in July 2012, while 163 deer fecal samples were collected during two sampling periods (March and June). The locations of deer fecal pellets were recorded via geographic information system mapping and microsatellite multi-locus genotyping was used to link the fecal samples to individual deer at both time points. Following subculture to sorbitol MacConkey agar and STEC CHROMagar, the pathogens were characterized by serotyping, stx profiling, and PCR-based fingerprinting; multilocus sequence typing (MLST) was performed on a subset. STEC and EHEC were cultured from 12 to 16% of cattle, respectively, and EPEC was found in 36%. Deer were significantly less likely to have a pathogen in March vs. June where the frequency of STEC, EHEC, and EPEC was 1, 6, and 22%, respectively. PCR fingerprinting and MLST clustered the cattle- and deer-derived strains together in a phylogenetic tree. Two STEC strains recovered from both animal species shared MLST and fingerprinting profiles, thereby providing evidence of interspecies transmission and highlighting the importance of wildlife species in pathogen shedding dynamics and persistence in the environment and cattle herds.

  17. Isolation of Shiga toxin 2f-producing Escherichia coli (O115:HNM) from an adult symptomatic patient in Fukuoka Prefecture, Japan.

    Science.gov (United States)

    Etoh, Yoshiki; Murakami, Koichi; Ichihara, Sachiko; Sera, Nobuyuki; Hamasaki, Mitsuhiro; Takenaka, Shigeyuki; Horikawa, Kazumi; Kawano, Kimiko; Takeishi, Tomoko; Kuwana, Yuka; Inoue, Asao; Nagatsu, Youko; Hira, Yasuko; Takahashi, Masanobu; Ito, Kenitiro

    2009-07-01

    Shiga toxin 2f-producing Escherichia coli (O115:HNM) with eae was isolated from a symptomatic patient in Fukuoka Prefecture, Japan. The patient was a 23-year-old male and his symptoms were diarrhea, abdominal pain, headaches and a fever (37.7 degrees C). He had eaten raw chicken meat, raw chicken eggs, cooked chicken meat and raw vegetables about 13 h prior to the onset of the symptoms. The patient's specimen was examined, and no diarrheagenic agents were detected except for Shiga toxin 2f-producing E. coli (STEC(2f)) with eae. This is the first report of the serotype O115:HNM possessing stx(2f). We discuss the necessity of routinely using stx(2f)-detecting PCR primers for detection of this enteric pathogen.

  18. Prevalence and pathogenicity of binary toxin–positive Clostridium difficile strains that do not produce toxins A and B

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    C. Eckert

    2015-01-01

    Full Text Available Clostridium difficile causes antibiotic-associated diarrhoea and pseudomembranous colitis. The main virulence factors of C. difficile are the toxins A (TcdA and B (TcdB. A third toxin, called binary toxin (CDT, can be detected in 17% to 23% of strains, but its role in human disease has not been clearly defined. We report six independent cases of patients with diarrhoea suspected of having C. difficile infection due to strains from toxinotype XI/PCR ribotype 033 or 033-like, an unusual toxinotype/PCR ribotype positive for CDT but negative for TcdA and TcdB. Four patients were considered truly infected by clinicians and were specifically treated with oral metronidazole. One of the cases was identified during a prevalence study of A−B−CDT+ strains. In this study, we screened a French collection of 220 nontoxigenic strains and found only one (0.5% toxinotype XI/PCR ribotype 033 or 033-like strain. The description of such strains raises the question of the role of binary toxin as a virulence factor and could have implications for laboratory diagnostics that currently rarely include testing for binary toxin.

  19. Faecal carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae and Shiga toxin-producing Escherichia coli in asymptomatic nursery children in Lower Saxony (Germany), 2014.

    Science.gov (United States)

    Harries, M; Dreesman, J; Rettenbacher-Riefler, S; Mertens, E

    2016-09-09

    Children may be at higher risk for carriage of antimicrobial-resistant bacteria because of higher usage of antimicrobials. They also have higher rates of Shiga toxin-producing Escherichia coli (STEC) infections than other population groups. Some infections, particularly in children, are asymptomatic, but still lead to the excretion of large numbers of bacteria and viruses that may cause clinical disease in other individuals. That is one reason why, in Lower Saxony as in other German federal states - asymptomatic carriers of STEC are excluded from nurseries and schools until three consecutive stool samples test negative in order to prevent secondary cases. The prevalence of children who are asymptomatic STEC carriers is unknown. But if it is high, this measure would have substantial socioeconomic effects on families. Infections with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) are an increasing problem for public health, especially for hospitals. However, there are no reliable estimates of the prevalence of asymptomatic ESBL-E carriers in Lower Saxony, as there is no mandatory requirement to report these carriers. In order to discuss the exclusion policies for children attending nurseries and ascertain a baseline of ESBL-E carriers, we conducted a cross-sectional study. The aim was to determine the prevalence of ESBL-E and STEC and identify risk factors for carriage in nursery children without diarrhoea (asymptomatic) aged 0-6 years in four selected districts in Northern Germany. During April-September 2014, we collected stool specimens with the support of voluntarily participating nurseries. We tested for STEC by PCR and for ESBL-E on chromogenic agar. Questionnaires answered by parents contained data on eating and drinking habits, outdoor activities, prior antibiotic treatment and animal contact for each participating child. We compared the epidemiological characteristics of ESBL-E carriers vs. non-carriers by using univariable analysis (P

  20. Characterization of an organism that produces type E botulinal toxin but which resembles Clostridium butyricum from the feces of an infant with type E botulism.

    Science.gov (United States)

    McCroskey, L M; Hatheway, C L; Fenicia, L; Pasolini, B; Aureli, P

    1986-01-01

    The apparent causative organism from the only reported case of type E infant botulism was isolated and characterized. Except for its ability to produce type E botulinal toxin, this organism (strain 5262) would be unquestionably identified as Clostridium butyricum. This is the second time an organism resembling a defined Clostridium species other than a member of the C. botulinum group has been implicated in infant botulism.

  1. Detection and isolation of the "Top 7" Shiga toxin-producing Escherichia coli in ground beef: comparison of the Rapidfinder kits to the USDA microbiology laboratory guidebook method

    Science.gov (United States)

    Shiga toxin-producing E. coli (STEC) O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 are often referred to as the “top 7” STEC, and these have been declared as adulterants in beef by the USDA Food Safety and Inspection Service (FSIS). The aim of this work was to compare the methods des...

  2. Presence of Potential Toxin-Producing Cyanobacteria in an Oligo-Mesotrophic Lake in Baltic Lake District, Germany: An Ecological, Genetic and Toxicological Survey

    OpenAIRE

    Dadheech, Pawan K.; Selmeczy, Géza B.; Vasas, Gábor; Padisák, Judit; Arp, Wolfgang; Tapolczai, Kálmán; Casper, Peter; Krienitz, Lothar

    2014-01-01

    Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichosper...

  3. Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam.

    Science.gov (United States)

    Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Van Minh, Pham; Wagenaar, Jaap A; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-09-09

    Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3(rd)-generation cephalosporins. These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.

  4. Detection of shiga-toxin producing E. coli (STEC) in leafy greens sold at local retail markets in Alexandria, Egypt.

    Science.gov (United States)

    Khalil, Rowaida K S; Gomaa, Mohamed A E; Khalil, Mahmoud I M

    2015-03-16

    Leafy green vegetables, a popular and an indispensable ingredient of the daily menus of Egyptians' diets, currently presents a great concern in terms of microbiological hazards. To the best of our knowledge, this is the first report that provides scientific evidence for prevalence of shiga-toxigenic Escherichia coli (STEC) in leafy greens sold at open air local retail markets and superstores in the Egyptian environment. A total of 486 conventional and organic leafy green samples that are eaten raw were collected from different areas in Alexandria, evaluated for total E. coli counts (ECCs), and screened for E. coli O157:H7 using conventional and molecular methods. Recovery of E. coli (≥10(2)CFU/g) from all studied types of leafy greens was indicative of fecal contamination. Total ECCs in conventional samples ranged from 5.47 to 2.56 log CFU/g. Based on their inability to ferment sorbitol on CT-SMAC media, 26 presumptive E. coli O157 isolates were detected in 71.4% (270/378) of the studied conventional samples. From all studied organic samples, only 2 types (organic cabbage and parsley, 16.7%) were contaminated with presumptive E. coli O157. All 28 isolates were further serotyped as E. coli O157 by latex agglutination test, and biochemically confirmed as E. coli. Multiplex PCR assays confirmed the ability of 21.4% (6/28) of the E. coli O157 strains to produce shiga-toxins (Stxs), and their virulence markers were as follows: stx1, 66.6% (4/6); stx2, 50% (3/6); stx1/stx2, 16.7% (1/6); eaeA, 83.3% (5/6); and hlyA, 16.7% (1/6). Only 2 strains recovered from conventional and organic parsley could possibly be classified as E. coli O157:H7 based on the presence of stx-genes (either stx1 or stx2 or both). Results of the present research highlight that high E. coli loads, together with recovery of STEC O157 isolates could pose serious health risks to the produce consumers. This emphasizes the urgent need for health authorities to value and utilize the existing knowledge to

  5. Detection of Shiga toxin-producing Escherichia coli by sandwich enzyme-linked immunosorbent assay using chicken egg yolk IgY antibodies.

    Science.gov (United States)

    Parma, Y R; Chacana, P A; Lucchesi, P M A; Rogé, A; Granobles Velandia, C V; Krüger, A; Parma, A E; Fernández-Miyakawa, M E

    2012-01-01

    Enterohemorrhagic Escherichia coli (EHEC), a subset of Shiga toxin producing E. coli (STEC) is associated with a spectrum of diseases that includes diarrhea, hemorrhagic colitis and a life-threatening hemolytic-uremic syndrome (HUS). Regardless of serotype, Shiga toxins (Stx1 and/or Stx2) are uniformly expressed by all EHEC, and so exploitable targets for laboratory diagnosis of these pathogens. In this study, a sandwich ELISA for determination of Shiga toxin (Stx) was developed using anti-Stx2B subunit antibodies and its performance was compared with that of the Vero cell assay and a commercial immunoassay kit. Chicken IgY was used as capture antibody and a HRP-conjugated rabbit IgG as the detection antibody. The anti-Stx2B IgY was harvested from eggs laid by hens immunized with a recombinant protein fragment. Several parameters were tested in order to optimize the sandwich ELISA assay, including concentration of antibodies, type and concentration of blocking agent, and incubation temperatures. Supernatants from 42 STEC strains of different serotypes and stx variants, including stx(2EDL933), stx(2vha), stx(2vhb), stx(2g), stx(1EDL933), and stx(1d) were tested. All Stx variants were detected by the sandwich ELISA, with a detection limit of 115 ng/ml Stx2. Twenty three strains negative for stx genes, including different bacteria species, showed no activity in Vero cell assay and produced negative results in ELISA, except for two strains. Our results show that anti-Stx2B IgY sandwich ELISA could be used in routine diagnosis as a rapid, specific and economic method for detection of Shiga toxin-producing E. coli.

  6. Detection of Shiga toxin-producing Escherichia coli by sandwich enzyme-linked immunosorbent assay using chicken egg yolk IgY antibodies

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    Yanil R Parma

    2012-06-01

    Full Text Available Enterohemorrhagic Escherichia coli (EHEC, a subset of Shiga toxin producing E. coli (STEC is associated with a spectrum of diseases that includes diarrhea, hemorrhagic colitis and a life-threatening hemolytic uremic syndrome (HUS. Regardless of serotype, Shiga toxins (Stx1 and/or Stx2 are uniformly expressed by all EHEC, and so exploitable targets for laboratory diagnosis of these pathogens. In this study, a sandwich ELISA for determination of Shiga toxin (Stx was developed using anti-Stx2 B subunit antibodies and its performance was compared with that of the Vero cell assay and a commercial immunoassay kit. Chicken IgY was used as capture antibody and a HRP-conjugated rabbit IgG as the detection antibody. The anti-Stx2B IgY was harvested from eggs laid by hens immunized with a recombinant protein fragment. Several parameters were tested in order to optimize the sandwich ELISA assay, including concentration of antibodies, type and concentration of blocking agent, and incubation temperatures. Supernatants from 42 STEC strains of different serotypes and stx variants, including stx2EDL933, stx2vha, stx2vhb, stx2g, stx1EDL933 and stx1d were tested. All Stx variants were detected by the sandwich ELISA, with a detection limit of 400 ng /ml Stx2. Twenty three strains negative for stx genes, including different bacteria species, showed no activity in Vero cell assay and produced negative results in ELISA, except for 2 strains. Our results show that anti-Stx2B IgY sandwich ELISA could be used in routine diagnosis as a rapid, specific and economic method for detection of Shiga toxin-producing E. coli.

  7. Shiga toxin-producing Escherichia coli in yaks (Bos grunniens from the Qinghai-Tibetan Plateau, China.

    Directory of Open Access Journals (Sweden)

    Xiangning Bai

    Full Text Available Shiga toxin (Stx-producing Escherichia coli (STEC are recognized as important human pathogens of public health concern. Many animals are the sources of STEC. In this study we determined the occurrence and characteristics of the STEC in yaks (Bos grunniens from the Qinghai-Tibetan plateau, China. A total of 728 yak fecal samples was collected from June to August, 2012 and was screened for the presence of the stx 1 and stx 2 genes by TaqMan real-time PCR after the sample was enriched in modified Tryptone Soya Broth. Of the 138 (18.96% stx 1 and/or stx 2-positive samples, 85 (61.59% were confirmed to have at least 1 STEC isolate present by culture isolation, from which 128 STEC isolates were recovered. All STEC isolates were serotyped, genotyped by pulsed-field gel electrophoresis (PFGE and characterized for the presence of 16 known virulence factors. Fifteen different O serogroups and 36 different O:H serotypes were identified in the 128 STEC isolates with 21 and 4 untypable for the O and H antigens respectively. One stx 1 subtype (stx 1a and 5 stx 2 subtypes (stx 2a, stx 2b, stx 2c, stx 2d and stx 2g were present in these STEC isolates. Apart from lpfA O157/OI-141, lpfA O157/OI-154, lpfA O113, katP and toxB which were all absent, other virulence factors screened (eaeA, iha, efa1, saa, paa, cnf1, cnf2, astA, subA, exhA and espP were variably present in the 128 STEC isolates. PFGE were successful for all except 5 isolates and separated them into 67 different PFGE patterns. For the 18 serotypes with 2 or more isolates, isolates of the same serotypes had the same or closely related PFGE patterns, demonstrating clonality of these serotypes. This study was the first report on occurrence and characteristics of STEC isolated from yaks (Bos grunniens from the Qinghai-Tibetan plateau, China, and extended the genetic diversity and reservoir host range of STEC.

  8. Molecular and Phylogenetic Characterization of Non-O157 Shiga Toxin-Producing Escherichia coli Strains in China.

    Science.gov (United States)

    Bai, Xiangning; Hu, Bin; Xu, Yanmei; Sun, Hui; Zhao, Ailan; Ba, Pengbin; Fu, Shanshan; Fan, Ruyue; Jin, Yujuan; Wang, Hong; Guo, Qiusheng; Xu, Xuebin; Lu, Shan; Xiong, Yanwen

    2016-01-01

    Shiga toxin-producing Escherichia coli (STEC) causes diarrhea and hemorrhagic colitis with life-threatening complications, such as hemolytic uremic syndrome. The aim of this study was to assess the molecular epidemiologic features of non-O157 STEC strains from different resources in China and illustrate the role of animal reservoirs or animal-derived foodstuffs in human STEC infections. A collection of 301 non-O157 STEC isolates from domestic and wild animals (i.e., cattle, goat, pig, yak, pika, and antelope), raw meats (i.e., beef, pork, mutton, chicken, and duck), diarrheal patients, and healthy carriers in different regions of China were selected in this study. Of the 301 analyzed STEC isolates, 67 serogroups, and 118 serotypes were identified; this included some predominant serogroups associated with human disease, such as O26, O45, O103, O111, and O121. Eighteen different combinations of stx subtypes were found. Eleven isolates carried the intimin gene eae, 93 isolates contained ehxA, and 73 isolates carried astA. The prevalence of other putative adhesion genes saa, paa, efa1, and toxB was 28.90% (87), 6.98% (21), 2.31% (7), and 1% (3), respectively. The phylogenetic distribution of isolates was analyzed by multilocus sequence typing (MLST). Ninety-four sequence types were assigned across the 301 isolates. A subset of isolates recovered from yak and pika residing in the similar wild environments, Qinghai-Tibetan plateau, showed similar genetic profiles and more tendencies to cluster together. Isolates from goat and mutton exhibited close genetic relatedness with those from human-derived isolates, providing evidence that transmission may have occurred locally within intraspecies or interspecies, and importantly, from animal reservoirs, or raw meats to humans. Comparing isolates in this study with highly virulent strains by MLST, along with serotyping and virulence profiles, it is conceivable that some of isolates from goat, yak, or raw meats may have potential

  9. Molecular and Phylogenetic Characterization of Non-O157 Shiga Toxin-Producing Escherichia coli Strains in China

    Directory of Open Access Journals (Sweden)

    Xiangning Bai

    2016-11-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC causes diarrhea and hemorrhagic colitis with life-threatening complications, such as hemolytic uremic syndrome. The aim of this study was to assess the molecular epidemiologic features of non-O157 STEC strains from different resources in China and illustrate the role of animal reservoirs or animal-derived foodstuffs in human STEC infections. A collection of 301 non-O157 STEC isolates from domestic and wild animals (i.e., cattle, goat, pig, yak, pika, and antelope, raw meats (i.e., beef, pork, mutton, chicken, and duck, diarrheal patients, and healthy carriers in different regions of China were selected in this study. Of the 301 analyzed STEC isolates, 67 serogroups and 118 serotypes were identified; this included some predominant serogroups associated with human disease, such as O26, O45, O103, O111 and O121. Eighteen different combinations of stx subtypes were found. Eleven isolates carried the intimin gene eae, 93 isolates contained ehxA, and 73 isolates carried astA. The prevalence of other putative adhesion genes saa, paa, efa1 and toxB was 28.90% (87, 6.98% (21, 2.31% (7, and 1% (3, respectively. The phylogenetic distribution of isolates was analyzed by multilocus sequence typing (MLST. Ninety-four sequence types were assigned across the 301 isolates. A subset of isolates recovered from yak and pika residing in the similar wild environments, Qinghai-Tibetan plateau, showed similar genetic profiles and more tendencies to cluster together. Isolates from goat and mutton exhibited close genetic relatedness with those from human-derived isolates, providing evidence that transmission may have occurred locally within intraspecies or interspecies, and importantly, from animal reservoirs or raw meats to humans. Comparing isolates in this study with highly virulent strains by MLST, along with serotyping and virulence profiles, it is conceivable that some of isolates from goat, yak, or raw meats may have

  10. Genotypes and virulence characteristics of Shiga toxin-producing Escherichia coli O104 strains from different origins and sources.

    Science.gov (United States)

    Miko, Angelika; Delannoy, Sabine; Fach, Patrick; Strockbine, Nancy A; Lindstedt, Björn Arne; Mariani-Kurkdjian, Patricia; Reetz, Jochen; Beutin, Lothar

    2013-12-01

    Sixty-two Escherichia coli strains carrying the wzxO104-gene from different sources, origins and time periods were analyzed for their serotypes, virulence genes and compared for genomic similarity by pulsed-field gel-electrophoresis (PFGE). The O104 antigen was present in 55 strains and the structurally and genetically related capsular antigen K9 in five strains. The presence of 49 genes associated with enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC) and enterohemorrhagic E. coli (EHEC) was investigated. Fifty-four strains of serotypes O104:H2 (n=1), O104:H4 (n=37), O104:H7 (n=5) and O104:H21 (n=11) produced Shiga-toxins (Stx). Among STEC O104, a close association between serotype, virulence gene profile and genomic similarity was found. EAEC virulence genes were only present in STEC O104:H4 strains. EHEC-O157 plasmid-encoded genes were only found in STEC O104:H2, O104:H7 and O104:H21 strains. None of the 62 O104 or K9 strains carried an eae-gene involved in the attaching and effacing phenotype. The 38 O104:H4 strains formed a single PFGE-cluster (>83.7% similarity). Thirty-one of these strains were from the European O104:H4 outbreak in 2011. The outbreak strains and older O104:H4 strains from Germany (2001), Georgia and France (2009) clustered together at>86.2% similarity. O104:H4 strains isolated between 2001 and 2009 differed for some plasmid-encoded virulence genes compared to the outbreak strains from 2011. STEC O104:H21 and STEC O104:H7 strains isolated in the U.S. and in Europe showed characteristic differences in their Stx-types, virulence gene and PFGE profiles indicating that these have evolved separately. E. coli K9 strains were not associated with virulence and were heterogeneous for their serotypes and PFGE profiles. Copyright © 2013 Elsevier GmbH. All rights reserved.

  11. Characterization of Shiga toxin producing E. coli and O157 serotype E. coli isolated in France from healthy domestic cattle.

    Science.gov (United States)

    Rogerie, F; Marecat, A; Gambade, S; Dupond, F; Beaubois, P; Lange, M

    2001-02-15

    A study was carried out in France in collaboration with the meat industry to investigate the occurrence and characteristics of Shiga toxin-producing E. coli (STEC) and O157 E. coli in a population of healthy bovines representative of French livestock. A total of 851 animals belonging to three bovine classes (106 young bulls, 374 dairy cows and 371 meat cows) were included in the study. Samples of feces and of the corresponding carcasses were collected from March 97 to August 97 in seven abattoirs spread throughout the national territory. STEC cultures from the 1702 samples were screened using PCR for the presence of stx genes. Positive samples were further subjected to colony blot hybridization and to O157-specific immunomagnetic separation. Probe-positive colonies and O157 colonies were then analyzed for the presence of virulence genes and phenotypic characters (serotype, Stx production). In 154 (18.1%) feces and 91 (10.7%) carcass samples stx genes were detected. Two hundred and twenty-two STEC colonies were isolated from 67 (7.9%) feces and 16 (1.9%) carcass samples, with 183 STEC isolated from feces and 39 from carcasses. Only eight O157 isolates were collected from feces samples. None of these O157 E. coli isolates presented stx genes and thus could not be considered as pathogenic regarding hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). In 3.2% of STEC isolated from feces and in 10.2% of STEC from carcasses eae genes were detected. In 17% of STEC from feces and in 30.7% from carcasses ehx genes were detected. Using these data, the 222 STEC colonies could be classified in 11 different 'virulence patterns' (presence/absence of stx1, stx2, eae and ehx genes), showing that more than 77% of isolates presented only one virulence factor. Only three STEC on 222 colonies (1.3%) presented the three virulence factors stx, eae and ehx in association, none of them reacting with antisera specific for enterohemorrhagic E. coli. (EHEC). These data, together

  12. Comparison of Agar Media for Detection and Quantification of Shiga Toxin-Producing Escherichia coli in Cattle Feces.

    Science.gov (United States)

    Stromberg, Zachary R; Lewis, Gentry L; Moxley, Rodney A

    2016-06-01

    The isolation and quantification of non-O157 Shiga toxin-producing Escherichia coli (STEC) from cattle feces are challenging. The primary objective of this study was to evaluate the performance of selected agar media in an attempt to identify an optimal medium for the detection and quantification of non-O157 STEC in cattle feces. Comparison studies were performed using CHROMagar STEC, Possé differential agar (Possé), Possé modified by the reduction or addition of antimicrobials, STEC heart infusion washed blood agar with mitomycin C (SHIBAM), and SHIBAM modified by the addition of antimicrobials. Fourteen STEC strains, two each belonging to serogroups O26, O45, O103, O111, O121, O145, and O157, were used to test detection in inoculated fecal suspensions at concentrations of 10(2) or 10(3) CFU/g. One STEC strain from each of these seven serogroups was used to estimate the concentration of recovered STEC in feces inoculated at 10(3), 10(4), or 10(5) CFU/g. Significantly more suspensions (P < 0.05) were positive for STEC when plated on Possé containing reduced concentrations of novobiocin and potassium tellurite compared with SHIBAM, but not SHIBAM modified by containing these same antimicrobials at the same concentrations. Numerically, more suspensions were positive for STEC by using this same form of modified Possé compared with Possé, but this difference was not statistically significant. More suspensions were positive for STEC cultured on CHROMagar STEC compared with those on Possé (P < 0.05) and on modified Possé (P = 0.05). Most inoculated fecal suspensions below 10(4) CFU/g of feces were underestimated or not quantifiable for the concentration of STEC by using CHROMagar STEC or modified Possé. These results suggest that CHROMagar STEC performs better than Possé or SHIBAM for detection of STEC in bovine feces, but adjustments in the concentrations of novobiocin and potassium tellurite in the latter two media result in significant improvements in their

  13. Taxonomic identity of type E botulinum toxin-producing Clostridium butyricum strains by sequencing of a short 16S rDNA region.

    Science.gov (United States)

    Pourshaban, Manoocheher; Franciosa, Giovanna; Fenicia, Lucia; Aureli, Paolo

    2002-08-27

    Several micro-organisms capable of producing botulinum neurotoxin type E, though phenotypically similar to Clostridium butyricum (a normally non-neurotoxigenic organism), have recently been isolated in Italy and China. Some of these micro-organisms had been implicated in food-borne botulism, a serious neuroparalytic disease. The taxonomic identity of the type E botulinum toxin-producing strains is confirmed here, through sequencing of a genus- and species-specific segment of the 16S rRNA gene. Confirmation leads to the conclusion that neurotoxigenic C. butyricum must be regarded as an emergent food-borne pathogen.

  14. Antibiotic Resistance and Virulence Potentials of Shiga Toxin-Producing Escherichia coli Isolates from Raw Meats of Slaughterhouses and Retail Markets in Korea.

    Science.gov (United States)

    Park, Hyun-Jung; Yoon, Jang Won; Heo, Eun-Jeong; Ko, Eun-Kyoung; Kim, Ki-Yeon; Kim, Young-Jo; Yoon, Hyang-Jin; Wee, Sung-Hwan; Park, Yong Ho; Moon, Jin San

    2015-09-01

    In this study, the prevalence of Shiga toxin-producing Escherichia coli (STEC) was investigated among raw meat or meat products from slaughterhouses and retail markets in South Korea, and their potential for antibiotic resistance and virulence was further analyzed. A total of 912 raw meats, including beef, pork, and chicken, were collected from 2008 to 2009. E. coli strains were frequently isolated in chicken meats (176/233, 75.9%), beef (102/217, 42.3%), and pork (109/235, 39.2%). Putative STEC isolates were further categorized, based on the presence or absence of the Shiga toxin (stx) genes, followed by standard O-serotyping. Polymerase chain reaction assays were used to detect the previously defined virulence genes in STEC, including Shiga toxins 1 and Shiga toxin 2 (stx1 and 2), enterohemolysin (ehxA), intimin (eaeA), STEC autoagglutination adhesion (saa), and subtilase cytotoxin (subAB). All carried both stx1 and eae genes, but none of them had the stx2, saa, or subAB genes. Six (50.0%) STEC isolates possessed the ehxA gene, which is known to be encoded by the 60-megadalton virulence plasmid. Our antibiogram profiling demonstrated that some STEC strains, particularly pork and chicken isolates, displayed a multiple drug-resistance phenotype. RPLA analysis revealed that all the stx1-positive STEC isolates produced Stx1 only at the undetectable level. Altogether, these results imply that the locus of enterocyte and effacement (LEE)-positive strains STEC are predominant among raw meats or meat products from slaughterhouses or retail markets in Korea.

  15. Botulinum Toxin

    Science.gov (United States)

    2009-01-01

    intercostal muscle (Hilmas, unpublished data). All serotypes showed a similar ability to produce complete muscular paralysis in ex vivo human intercostal...routes of exposure include, in order of descending frequency: dysphagia, xerostomia, diplopia, dysarthria, fatigue , ptosis of the eyelids...Medical and Public Health Manage- ment. JAMA 285: 1059-70. Bakry, N., Kamata, Y., Simpson, L. (1997). Expression of botu- linum toxin binding sites in

  16. The Regulation of Expression of the Stx2d Toxins in Shiga Toxin-producing Escherichia coli O91:H21 Strain B2F1

    Science.gov (United States)

    2002-01-01

    Canada, E.coli O157:H7 was isolated during an outbreak of hemorrhagic colitis (HC) in a nursing home. Bacteria from that outbreak produced Shiga...the same investigators showed evidence of current or recent infection with Verotoxin-producing bacteria in 75% of the children with HUS (Karmali et...thrombocytopenic purpura (TTP) (Griffin et al., 1988). 3 The O157:H7 serotype of STEC is the most common one in the United States and Canada, but many non

  17. Oral Multiple Sclerosis Drugs Inhibit the In vitro Growth of Epsilon Toxin Producing Gut Bacterium, Clostridium perfringens

    OpenAIRE

    Rumah, Kareem R.; Vartanian, Timothy K.; Fischetti, Vincent A.

    2017-01-01

    There are currently three oral medications approved for the treatment of multiple sclerosis (MS). Two of these medications, Fingolimod, and Teriflunomide, are considered to be anti-inflammatory agents, while dimethyl fumarate (DMF) is thought to trigger a robust antioxidant response, protecting vulnerable cells during an MS attack. We previously proposed that epsilon toxin from the gut bacterium, Clostridium perfringens, may initiate newly forming MS lesions due to its tropism for blood-brain...

  18. Ts8 scorpion toxin inhibits the Kv4.2 channel and produces nociception in vivo.

    Science.gov (United States)

    Pucca, Manuela Berto; Cerni, Felipe Augusto; Cordeiro, Francielle Almeida; Peigneur, Steve; Cunha, Thiago Mattar; Tytgat, Jan; Arantes, Eliane Candiani

    2016-09-01

    The venom from the scorpion Tityus serrulatus (Ts) has been extensively studied mainly because of its rich cocktail of neurotoxins. Neurotoxins are the major and the most known components based on their modulation of voltage-gated ion channels. Until now, electrophysiological studies demonstrated that the Ts venom comprises toxins that affect Nav and Kv channels. However, although many studies have been conducted in this field, many peptides from Ts venom await further studies, including Ts8 toxin. Here we report the isolation and electrophysiological study of Ts8. The toxin Ts19 Frag-II was used as negative control. Ts8 demonstrates, among 20 tested channels, to be a selective modulator of Kv4.2 channels. Based on studies investigating the involvement of Kv4.2 on controlling nociception, we further investigated the modulation of pain by Ts8. Using intraplantar injections, Ts8 induced overt nociception (licking and lifting behaviors) and decreased the mechanical nociceptive threshold (hyperalgesia). Furthermore, the hyperalgesia was prolonged when intrathecal injections were performed. Independent of the severity, most of the victims stung by Ts scorpions report an intense and persistent pain as the major manifestation. The new role of Ts8 on nociception could explain, at least partially, this phenomenon. Additionally, our study also stresses the involvement of toxins specific to Nav channels and inflammatory mediators on the Ts painful sting. This work provides useful insights for a better understanding of the prolonged and intense pain associated with Ts envenoming for the development of specific therapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. [Comparative evaluation of stx-PCR, Vero cell assay and Verotoxin enzyme imminoassay for detection of Shiga toxin-producing Escherichia coli].

    Science.gov (United States)

    Bai, Li; Hu, Yujie; Wang, Jiahui; Wu, Qing; He, Yingying; Wang, Wei; Gan, Xin; Han, Chunhui; Li, Fengqin; Xu, Jin

    2014-09-01

    To evaluate the suitability of stx-PCR, Vero cell assay and commercial enzyme immunoassay for detection of Shiga toxin Escherichia coli and to compare sensitivity and specificity of three different methods for detection of Shiga toxin-producing Escherichia coli. Using stx-PCR, Vero cell assay and commercial enzyme immunoassay to detect 35 Escherichia coli reference strains and 45 strains isolated from food. The three methods all had good specificity. 31 strains gave positive reaction in the Vero cell assay and in the stx-PCR. The consistency between the Vero cell assay and stx-PCR was 100%. Only 38 strains can be detected by commercial enzyme immunoassay. stx-PCR method can serve as a routine rapid detection method in the laboratory. Vero cell assay is recommended to be the gold standard to determine whether the bacteria had the functionally active toxin. Commercial kit was suitable for preliminary rapid detection during clinical testing and outbreaks of food-borne disease.

  20. Enterotoxigenic profiling of emetic toxin- and enterotoxin-producing Bacillus cereus, Isolated from food, environmental, and clinical samples by multiplex PCR.

    Science.gov (United States)

    Forghani, Fereidoun; Kim, Jung-Beom; Oh, Deog-Hwan

    2014-11-01

    Bacillus cereus comprises the largest group of endospore-forming bacteria and can cause emetic and diarrheal food poisoning. A total of 496 B. cereus strains isolated from various sources (food, environmental, clinical) were assessed by a multiplex PCR for the presence of enterotoxin genes. The detection rate of nheA, entFM, hblC, and cytK enterotoxin genes among all B. cereus strains was 92.33%, 77.21%, 59.47%, and 47.58%, respectively. Enterotoxigenic profiles were determined in emetic toxin- (8 patterns) and enterotoxin-producing strains (12 patterns). The results provide important information on toxin prevalence and toxigenic profiles of B. cereus from various sources. Our findings revealed that B. cereus must be considered a serious health hazard and Bacillus thuringiensis should be considered of a greater potential concern to food safety among all B. cereus group members. Also, there is need for intensive and continuous monitoring of products embracing both emetic toxin and enterotoxin genes. © 2014 Institute of Food Technologists®

  1. Phenotypic and Genotypic Characteristics of Shiga Toxin-Producing Escherichia coli Isolated from Surface Waters and Sediments in a Canadian Urban-Agricultural Landscape.

    Science.gov (United States)

    Nadya, Stephanie; Delaquis, Pascal; Chen, Jessica; Allen, Kevin; Johnson, Roger P; Ziebell, Kim; Laing, Chad; Gannon, Victor; Bach, Susan; Topp, Edward

    2016-01-01

    A hydrophobic grid membrane filtration-Shiga toxin immunoblot method was used to examine the prevalence of Shiga toxin-producing Escherichia coli (STEC) in four watersheds located in the Lower Mainland of British Columbia, Canada, a region characterized by rapid urbanization and intensive agricultural activity. STEC were recovered from 21.6, 23.2, 19.5, and 9.2% of surface water samples collected monthly from five sites in each watershed over a period of 1 year. Overall prevalence was subject to seasonal variation however, ranging between 13.3% during fall months and 34.3% during winter months. STEC were also recovered from 23.8% of sediment samples collected in one randomly selected site. One hundred distinct STEC isolates distributed among 29 definitive and 4 ambiguous or indeterminate serotypes were recovered from water and sediments, including isolates from Canadian "priority" serogroups O157 (3), O26 (4), O103 (5), and O111 (7). Forty seven isolates were further characterized by analysis of whole genome sequences to detect Shiga toxin gene (stx 1 and stx 2), intimin gene (eaeA) allelic variants and acquired virulence factors. These analyses collectively showed that surface waters from the region support highly diverse STEC populations that include strains with virulence factors commonly associated with human pathotypes. The present work served to characterize the microbiological hazard implied by STEC to support future assessments of risks to public health arising from non-agricultural and agricultural uses of surface water resources in the region.

  2. Top-Down Proteomic Identification of Shiga Toxin 2 Subtypes from Shiga Toxin-Producing Escherichia coli by Matrix-Assisted Laser Desorption Ionization–Tandem Time of Flight Mass Spectrometry

    Science.gov (United States)

    Zaragoza, William J.; Sultan, Omar; Woo, Nathan; Quiñones, Beatriz; Cooley, Michael B.; Mandrell, Robert E.

    2014-01-01

    We have analyzed 26 Shiga toxin-producing Escherichia coli (STEC) strains for Shiga toxin 2 (Stx2) production using matrix-assisted laser desorption ionization (MALDI)–tandem time of flight (TOF-TOF) tandem mass spectrometry (MS/MS) and top-down proteomic analysis. STEC strains were induced to overexpress Stx2 by overnight culturing on solid agar supplemented with either ciprofloxacin or mitomycin C. Harvested cells were lysed by bead beating, and unfractionated bacterial cell lysates were ionized by MALDI. The A2 fragment of the A subunit and the mature B subunit of Stx2 were analyzed by MS/MS. Sequence-specific fragment ions were used to identify amino acid subtypes of Stx2 using top-down proteomic analysis using software developed in-house at the U.S. Department of Agriculture (USDA). Stx2 subtypes (a, c, d, f, and g) were identified on the basis of the mass of the A2 fragment and the B subunit as well as from their sequence-specific fragment ions by MS/MS (postsource decay). Top-down proteomic identification was in agreement with DNA sequencing of the full Stx2 operon (stx2) for all strains. Top-down results were also compared to a bioassay using a Vero-d2EGFP cell line. Our results suggest that top-down proteomic identification is a rapid, highly specific technique for distinguishing Stx2 subtypes. PMID:24584253

  3. Top-down proteomic identification of Shiga toxin 2 subtypes from Shiga toxin-producing Escherichia coli by matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry.

    Science.gov (United States)

    Fagerquist, Clifton K; Zaragoza, William J; Sultan, Omar; Woo, Nathan; Quiñones, Beatriz; Cooley, Michael B; Mandrell, Robert E

    2014-05-01

    We have analyzed 26 Shiga toxin-producing Escherichia coli (STEC) strains for Shiga toxin 2 (Stx2) production using matrix-assisted laser desorption ionization (MALDI)-tandem time of flight (TOF-TOF) tandem mass spectrometry (MS/MS) and top-down proteomic analysis. STEC strains were induced to overexpress Stx2 by overnight culturing on solid agar supplemented with either ciprofloxacin or mitomycin C. Harvested cells were lysed by bead beating, and unfractionated bacterial cell lysates were ionized by MALDI. The A2 fragment of the A subunit and the mature B subunit of Stx2 were analyzed by MS/MS. Sequence-specific fragment ions were used to identify amino acid subtypes of Stx2 using top-down proteomic analysis using software developed in-house at the U.S. Department of Agriculture (USDA). Stx2 subtypes (a, c, d, f, and g) were identified on the basis of the mass of the A2 fragment and the B subunit as well as from their sequence-specific fragment ions by MS/MS (postsource decay). Top-down proteomic identification was in agreement with DNA sequencing of the full Stx2 operon (stx2) for all strains. Top-down results were also compared to a bioassay using a Vero-d2EGFP cell line. Our results suggest that top-down proteomic identification is a rapid, highly specific technique for distinguishing Stx2 subtypes.

  4. O-antigen and virulence profiling of Shiga toxin-producing Escherichia coli by a rapid and cost-effective DNA microarray colorimetric method

    OpenAIRE

    Beatriz eQuiñones; Swimley, Michelle S.; Koh-Eun eNarm; Patel, Ronak N.; Cooley, Michael B.; Mandrell, Robert E.

    2012-01-01

    Shiga toxin-producing Escherichia coli (STEC) is a leading cause of foodborne illness worldwide. The present study developed the use of DNA microarrays with the ampliPHOX colorimetric method to rapidly detect and genotype STEC strains. A low-density 30-mer oligonucleotide DNA microarray was designed to target O-antigen gene clusters of eleven E. coli serogroups (O26, O45, O91, O103, O104, O111, O113, O121, O128, O145 and O157) that have been associated with the majority of STEC infections. ...

  5. Molecular investigation of tRNA genes integrity and its relation to pathogenicity islands in Shiga toxin-producing Escherichia coli (STEC) strains

    OpenAIRE

    Novais,Rogério Carlos; Chaves,Marcela Cassin; Gonzalez,Alice Gonçalves Martins; Andrade,João Ramos Costa

    2004-01-01

    tRNA genes are known target sites for the integration of pathogenicity islands (PAI) and other genetic elements, such as bacteriophages, into bacterial genome. In most STEC (Shiga toxin-producing Escherichia coli), the PAI called LEE (locus of enterocyte effacement) is related to bacterial virulence and is mostly associated to the tRNA genes selC and pheU. In this work, we first investigated the relationship of LEE with tRNA genes selC and pheU in 43 STEC strains. We found that 28 strains (65...

  6. Growth of Escherichia coli O157:H7, Non-O157 Shiga Toxin-Producing Escherichia coli , and Salmonella in Water and Hydroponic Fertilizer Solutions.

    Science.gov (United States)

    Shaw, Angela; Helterbran, Kara; Evans, Michael R; Currey, Christopher

    2016-12-01

    The desire for local, fresh produce year round is driving the growth of hydroponic growing systems in the United States. Many food crops, such as leafy greens and culinary herbs, grown within hydroponics systems have their root systems submerged in recirculating nutrient-dense fertilizer solutions from planting through harvest. If a foodborne pathogen were introduced into this water system, the risk of contamination to the entire crop would be high. Hence, this study was designed to determine whether Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli , and Salmonella were able to survive and reproduce in two common hydroponic fertilizer solutions and in water or whether the bacteria would be killed or suppressed by the fertilizer solutions. All the pathogens grew by 1 to 6 log CFU/ml over a 24-h period, depending on the solution. E. coli O157:H7 reached higher levels in the fertilizer solution with plants (3.12 log CFU/ml), whereas non-O157 Shiga toxin-producing E. coli and Salmonella reached higher levels in the fertilizer solution without plants (1.36 to 3.77 log CFU/ml). The foodborne pathogens evaluated here survived for 24 h in the fertilizer solution, and populations grew more rapidly in these solutions than in plain water. Therefore, human pathogens entering the fertilizer solution tanks in hydroponic systems would be expected to rapidly propagate and spread throughout the system and potentially contaminate the entire crop.

  7. Comparison of Alternaria spp. collected in Italy from apple with A. mali and other AM-toxin producing strains.

    Science.gov (United States)

    Rotondo, F; Collina, M; Brunelli, A; Pryor, B M

    2012-12-01

    Since 1999, a disease of apple caused by an Alternaria sp. has been affecting orchards in northern Italy resulting in necrotic spots on leaves and on fruit. Forty-four single-spored isolates were obtained from diseased plant materials to investigate the diversity of this fungus in Italy and to compare these isolates to isolates of Alternaria associated with apple disease in previous studies, including A. mali, causal agent of apple blotch. All isolates, including the reference strains, were tested for pathogenicity utilizing in vitro bioassays on detached leaf or on fruit ('Golden Delicious'). In addition, morphological characterizations were conducted describing both the three-dimensional sporulation pattern and the colony morphology of each isolate. In order to assess the genetic diversity within the Italian Alternaria population, sequence characterization of specific loci and anonymous regions (endoPG, OPA1-3, OPA2-1, and OPA10-2) and genetic fingerprinting based on amplified fragment length polymorphism and inter simple sequence repeat markers were performed. The single spore isolates exhibited differential pathogenicity, which did not correlate with the morphological groupings or to groupings defined by molecular approaches. Moreover, 10 pathogenic isolates out of the 44 single-spored tested were positive for the host-specific AM-toxin gene based upon polymerase chain reaction amplification using specific primers for the AM-toxin gene. This suggests that the production of the AM-toxin may be involved in pathogenesis by some of the Italian isolates of A. alternata from apple. However, this research also suggests that a number of different Alternaria genotypes and morphotypes may be responsible for the apple disease in Italy and that a single taxon cannot be defined as the sole causal agent.

  8. Evaluation of the simultaneous effects of a heat stabilized starter ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    2016-09-28

    Sep 28, 2016 ... the interval of 100 to 120 g/L. The use of the dried starter granules revealed to be an efficient alternative to produce sorghum beer with ... Tchoukoutou, the Benin opaque sorghum beer, is produced from guinea corn ... pH, titratable acidity, ethanol, glucose, raffinose, fructose, maltose, yeast, LAB and total ...

  9. Oral Multiple Sclerosis Drugs Inhibit theIn vitroGrowth of Epsilon Toxin Producing Gut Bacterium,Clostridium perfringens.

    Science.gov (United States)

    Rumah, Kareem R; Vartanian, Timothy K; Fischetti, Vincent A

    2017-01-01

    There are currently three oral medications approved for the treatment of multiple sclerosis (MS). Two of these medications, Fingolimod, and Teriflunomide, are considered to be anti-inflammatory agents, while dimethyl fumarate (DMF) is thought to trigger a robust antioxidant response, protecting vulnerable cells during an MS attack. We previously proposed that epsilon toxin from the gut bacterium, Clostridium perfringens , may initiate newly forming MS lesions due to its tropism for blood-brain barrier (BBB) vasculature and central nervous system myelin. Because gut microbiota will be exposed to these oral therapies prior to systemic absorption, we sought to determine if these compounds affect C. perfringens growth in vitro . Here we show that Fingolimod, Teriflunomide, and DMF indeed inhibit C. perfringens growth. Furthermore, several compounds similar to DMF in chemical structure, namely α, β unsaturated carbonyls, also known as Michael acceptors, inhibit C. perfringens . Sphingosine, a Fingolimod homolog with known antibacterial properties, proved to be a potent C. perfringens inhibitor with a Minimal Inhibitory Concentration similar to that of Fingolimod. These findings suggest that currently approved oral MS therapies and structurally related compounds possess antibacterial properties that may alter the gut microbiota. Moreover, inhibition of C. perfringens growth and resulting blockade of epsilon toxin production may contribute to the clinical efficacy of these disease-modifying drugs.

  10. Oral Multiple Sclerosis Drugs Inhibit the In vitro Growth of Epsilon Toxin Producing Gut Bacterium, Clostridium perfringens

    Science.gov (United States)

    Rumah, Kareem R.; Vartanian, Timothy K.; Fischetti, Vincent A.

    2017-01-01

    There are currently three oral medications approved for the treatment of multiple sclerosis (MS). Two of these medications, Fingolimod, and Teriflunomide, are considered to be anti-inflammatory agents, while dimethyl fumarate (DMF) is thought to trigger a robust antioxidant response, protecting vulnerable cells during an MS attack. We previously proposed that epsilon toxin from the gut bacterium, Clostridium perfringens, may initiate newly forming MS lesions due to its tropism for blood-brain barrier (BBB) vasculature and central nervous system myelin. Because gut microbiota will be exposed to these oral therapies prior to systemic absorption, we sought to determine if these compounds affect C. perfringens growth in vitro. Here we show that Fingolimod, Teriflunomide, and DMF indeed inhibit C. perfringens growth. Furthermore, several compounds similar to DMF in chemical structure, namely α, β unsaturated carbonyls, also known as Michael acceptors, inhibit C. perfringens. Sphingosine, a Fingolimod homolog with known antibacterial properties, proved to be a potent C. perfringens inhibitor with a Minimal Inhibitory Concentration similar to that of Fingolimod. These findings suggest that currently approved oral MS therapies and structurally related compounds possess antibacterial properties that may alter the gut microbiota. Moreover, inhibition of C. perfringens growth and resulting blockade of epsilon toxin production may contribute to the clinical efficacy of these disease-modifying drugs. PMID:28180112

  11. Organic Heat Stabilizers for Polyvinyl Chloride (PVC): A Synergistic Behavior of Eugenol and Uracil Derivative

    Science.gov (United States)

    Asawakosinchai, Aran; Jubsilp, Chanchira; Mora, Phattarin; Rimdusit, Sarawut

    2017-09-01

    Recycling ability, mechanical, and thermal properties of PVC stabilized with organic heat stabilizers, i.e., uracil (DAU) and eugenol were investigated to substitute PVCs stabilized with commercial lead, Ca/Zn, and organic-based stabilizer for PVC pipe production. PVC stabilized with the DAU and the eugenol can be processable at 30 °C lower than that of the PVC stabilized with commercial heat stabilizers. The most remarkable short-term thermal stability belonged to the PVC stabilized with the DAU, and its original color can be maintained at least up to 3 processing cycles. Synergistic behavior in thermal stability of the PVC mixed with DAU and eugenol at mass ratios of 1.5:1.5 was observed. Mechanical properties of DAU- and eugenol-stabilized PVC were higher than the samples with other heat stabilizers. Glass transition temperature of the PVC stabilized with all heat stabilizers was determined to be 99 °C with the exception of the value of 89 °C for eugenol-stabilized PVC. Therefore, the DAU and the eugenol showed high potential to be used as an organic heat stabilizer for PVC because of their non-toxic and good heat resistance properties.

  12. Organic Heat Stabilizers for Polyvinyl Chloride (PVC): A Synergistic Behavior of Eugenol and Uracil Derivative

    Science.gov (United States)

    Asawakosinchai, Aran; Jubsilp, Chanchira; Mora, Phattarin; Rimdusit, Sarawut

    2017-10-01

    Recycling ability, mechanical, and thermal properties of PVC stabilized with organic heat stabilizers, i.e., uracil (DAU) and eugenol were investigated to substitute PVCs stabilized with commercial lead, Ca/Zn, and organic-based stabilizer for PVC pipe production. PVC stabilized with the DAU and the eugenol can be processable at 30 °C lower than that of the PVC stabilized with commercial heat stabilizers. The most remarkable short-term thermal stability belonged to the PVC stabilized with the DAU, and its original color can be maintained at least up to 3 processing cycles. Synergistic behavior in thermal stability of the PVC mixed with DAU and eugenol at mass ratios of 1.5:1.5 was observed. Mechanical properties of DAU- and eugenol-stabilized PVC were higher than the samples with other heat stabilizers. Glass transition temperature of the PVC stabilized with all heat stabilizers was determined to be 99 °C with the exception of the value of 89 °C for eugenol-stabilized PVC. Therefore, the DAU and the eugenol showed high potential to be used as an organic heat stabilizer for PVC because of their non-toxic and good heat resistance properties.

  13. Heterogeneity in Induction Level, Infection Ability, and Morphology of Shiga Toxin-Encoding Phages (Stx Phages) from Dairy and Human Shiga Toxin-Producing Escherichia coli O26:H11 Isolates

    Science.gov (United States)

    Bonanno, Ludivine; Petit, Marie-Agnès; Loukiadis, Estelle; Michel, Valérie

    2016-01-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) bacteria are foodborne pathogens responsible for diarrhea and hemolytic-uremic syndrome (HUS). Shiga toxin, the main STEC virulence factor, is encoded by the stx gene located in the genome of a bacteriophage inserted into the bacterial chromosome. The O26:H11 serotype is considered to be the second-most-significant HUS-causing serotype worldwide after O157:H7. STEC O26:H11 bacteria and their stx-negative counterparts have been detected in dairy products. They may convert from the one form to the other by loss or acquisition of Stx phages, potentially confounding food microbiological diagnostic methods based on stx gene detection. Here we investigated the diversity and mobility of Stx phages from human and dairy STEC O26:H11 strains. Evaluation of their rate of in vitro induction, occurring either spontaneously or in the presence of mitomycin C, showed that the Stx2 phages were more inducible overall than Stx1 phages. However, no correlation was found between the Stx phage levels produced and the origin of the strains tested or the phage insertion sites. Morphological analysis by electron microscopy showed that Stx phages from STEC O26:H11 displayed various shapes that were unrelated to Stx1 or Stx2 types. Finally, the levels of sensitivity of stx-negative E. coli O26:H11 to six Stx phages differed among the 17 strains tested and our attempts to convert them into STEC were unsuccessful, indicating that their lysogenization was a rare event. PMID:26826235

  14. Prevalence and characterization of Listeria monocytogenes, Salmonella and Shiga toxin-producing Escherichia coli isolated from small Mexican retail markets of queso fresco.

    Science.gov (United States)

    Soto Beltran, Marcela; Gerba, Charles P; Porto Fett, Anna; Luchansky, John B; Chaidez, Cristobal

    2015-01-01

    Queso fresco (QF) is a handmade cheese consumed and produced in Latin America. In Mexico, QF production is associated with a microbiological risk. The aim of the study was to determine the incidence and characterization of Listeria monocytogenes, Salmonella spp., and Shiga toxin-producing Escherichia coli (STEC) in QF from retail markets of the north-western State of Sinaloa, Mexico, and to assess the effect of physicochemical parameters on Listeria presence. A total of 75 QF samples were obtained. L. monocytogenes, E. coli, and coliforms were detected in 9.3, 94, and 100%, respectively. Salmonella was not detected. STEC isolates showed virulence genes. Microbial loads were above the maximum values recommended by the Official Mexican Standards. Physicochemical parameters such as water activity (aw), moisture content, pH, and salinity played a role in Listeria prevalence in QF. Rigorous control in QF made in Culiacan, Mexico is needed to reduce the risk of foodborne pathogens.

  15. Stool C difficile toxin

    Science.gov (United States)

    Antibiotic associated colitis - toxin; Colitis - toxin; Pseudomembranous - toxin; Necrotizing colitis - toxin; C difficile - toxin ... not recently taken antibiotics. This condition is called pseudomembranous colitis .

  16. Comparative genomic analysis of two novel sporadic Shiga toxin-producing Escherichia coli O104:H4 strains isolated 2011 in Germany.

    Directory of Open Access Journals (Sweden)

    Erhard Tietze

    Full Text Available A large outbreak of gastrointestinal disease occurred in 2011 in Germany which resulted in almost 4000 patients with acute gastroenteritis or hemorrhagic colitis, 855 cases of a hemolytic uremic syndrome and 53 deaths. The pathogen was an uncommon, multiresistant Escherichia coli strain of serotype O104:H4 which expressed a Shiga toxin characteristic of enterohemorrhagic E. coli and in addition virulence factors common to enteroaggregative E. coli. During post-epidemic surveillance of Shiga toxin-producing E. coli (STEC all but two of O104:H4 isolates were indistinguishable from the epidemic strain. Here we describe two novel STEC O104:H4 strains isolated in close spatiotemporal proximity to the outbreak which show a virulence gene panel, a Shiga toxin-mediated cytotoxicity towards Vero cells and aggregative adherence to Hep-2 cells comparable to the outbreak strain. They differ however both from the epidemic strain and from each other, by their antibiotic resistance phenotypes and some other features as determined by routine epidemiological subtyping methods. Whole genome sequencing of these two strains, of ten outbreak strain isolates originating from different time points of the outbreak and of one historical sporadic EHEC O104:H4 isolate was performed. Sequence analysis revealed a clear phylogenetic distance between the two variant strains and the outbreak strain finally identifying them as epidemiologically unrelated isolates from sporadic cases. These findings add to the knowledge about this emerging pathogen, illustrating a certain diversity within the bacterial core genome as well as loss and gain of accessory elements. Our results do also support the view that distinct new variants of STEC O104:H4 repeatedly might originate from yet unknown reservoirs, rather than that there would be a continuous diversification of a single epidemic strain established and circulating in Germany after the large outbreak in 2011.

  17. Comparative genomic analysis of two novel sporadic Shiga toxin-producing Escherichia coli O104:H4 strains isolated 2011 in Germany.

    Science.gov (United States)

    Tietze, Erhard; Dabrowski, Piotr Wojciech; Prager, Rita; Radonic, Aleksandar; Fruth, Angelika; Auraß, Philipp; Nitsche, Andreas; Mielke, Martin; Flieger, Antje

    2015-01-01

    A large outbreak of gastrointestinal disease occurred in 2011 in Germany which resulted in almost 4000 patients with acute gastroenteritis or hemorrhagic colitis, 855 cases of a hemolytic uremic syndrome and 53 deaths. The pathogen was an uncommon, multiresistant Escherichia coli strain of serotype O104:H4 which expressed a Shiga toxin characteristic of enterohemorrhagic E. coli and in addition virulence factors common to enteroaggregative E. coli. During post-epidemic surveillance of Shiga toxin-producing E. coli (STEC) all but two of O104:H4 isolates were indistinguishable from the epidemic strain. Here we describe two novel STEC O104:H4 strains isolated in close spatiotemporal proximity to the outbreak which show a virulence gene panel, a Shiga toxin-mediated cytotoxicity towards Vero cells and aggregative adherence to Hep-2 cells comparable to the outbreak strain. They differ however both from the epidemic strain and from each other, by their antibiotic resistance phenotypes and some other features as determined by routine epidemiological subtyping methods. Whole genome sequencing of these two strains, of ten outbreak strain isolates originating from different time points of the outbreak and of one historical sporadic EHEC O104:H4 isolate was performed. Sequence analysis revealed a clear phylogenetic distance between the two variant strains and the outbreak strain finally identifying them as epidemiologically unrelated isolates from sporadic cases. These findings add to the knowledge about this emerging pathogen, illustrating a certain diversity within the bacterial core genome as well as loss and gain of accessory elements. Our results do also support the view that distinct new variants of STEC O104:H4 repeatedly might originate from yet unknown reservoirs, rather than that there would be a continuous diversification of a single epidemic strain established and circulating in Germany after the large outbreak in 2011.

  18. Phenotypic and genotypic characteristics of Shiga toxin-producing Escherichia coli isolated from surface waters and sediments in a Canadian urban-agricultural landscape

    Directory of Open Access Journals (Sweden)

    Stephanie eNadya

    2016-04-01

    Full Text Available A hydrophobic grid membrane filtration – Shiga toxin immunoblot method was used to examine the prevalence of Shiga toxin-producing Escherichia coli (STEC in four watersheds located in the Lower Mainland of British Columbia, Canada, a region characterized by rapid urbanization and intensive agricultural activity. STEC were recovered from 21.6, 23.2, 19.5 and 9.2 % of surface water samples collected monthly from five sites in each watershed over a period of one year. Overall prevalence was subject to seasonal variation however, ranging between 13.3 % during fall months and 34.3 % during winter months. STEC were also recovered from 23.8 % of sediment samples collected in one randomly selected site. One hundred distinct STEC isolates distributed among 29 definitive and 4 ambiguous or indeterminate serotypes were recovered from water and sediments, including isolates from Canadian priority serogroups O157 (3, O26 (4, O103 (5 and O111 (7. Forty seven isolates were further characterized by analysis of whole genome sequences to detect Shiga toxin gene (stx 1 and stx 2, intimin gene (eaeA allelic variants and acquired virulence factors. These analyses collectively showed that surface waters from the region support highly diverse STEC populations that include strains with virulence factors commonly associated with human pathotypes. The present work served to characterize the microbiological hazard implied by STEC to support future assessments of risks to public health arising from non-agricultural and agricultural uses of surface water resources in the region.

  19. Prevalence of shiga toxin producing Escherichia coli, Salmonella enterica, and Listeria monocytogenes at public access watershed sites in a California Central Coast agricultural region

    Science.gov (United States)

    Cooley, Michael B.; Quiñones, Beatriz; Oryang, David; Mandrell, Robert E.; Gorski, Lisa

    2014-01-01

    Produce contaminated with enteric pathogens is a major source of foodborne illness in the United States. Lakes, streams, rivers, and ponds were sampled with Moore swabs bi-monthly for over 2 years at 30 locations in the vicinity of a leafy green growing region on the Central California Coast and screened for Shiga toxin producing Escherichia coli (STEC), Salmonella enterica, and Listeria monocytogenes to evaluate the prevalence and persistence of pathogen subtypes. The prevalence of STEC from 1386 samples was 11%; 110 samples (8%) contained E. coli O157:H7 with the highest prevalence occurring close to cattle operations. Non-O157 STEC isolates represented major clinical O-types and 57% contained both shiga toxin types 1 and 2 and intimin. Multiple Locus Variable Number Tandem Repeat Analysis of STEC isolates indicated prevalent strains during the period of study. Notably, Salmonella was present at high levels throughout the sampling region with 65% prevalence in 1405 samples resulting in 996 isolates with slightly lower prevalence in late autumn. There were 2, 8, and 14 sites that were Salmonella-positive over 90, 80, and 70% of the time, respectively. The serotypes identified most often were 6,8:d:-, Typhimurium, and Give. Interestingly, analysis by Pulsed Field Gel Electrophoresis indicated persistence and transport of pulsotypes in the region over several years. In this original study of L. monocytogenes in the region prevalence was 43% of 1405 samples resulting in 635 individual isolates. Over 85% of the isolates belonged to serotype 4b with serotypes 1/2a, 1/2b, 3a, 4d with 4e representing the rest, and there were 12 and 2 sites that were positive over 50 and 80% of the time, respectively. Although surface water is not directly used for irrigation in this region, transport to the produce can occur by other means. This environmental survey assesses initial contamination levels toward an understanding of transport leading to produce recalls or outbreaks. PMID

  20. Identification and epidemiological description of enterohemorrhagic Escherichia coli O157 strains producing low amounts of Shiga toxin 2 in Aichi Prefecture, Japan.

    Science.gov (United States)

    Matsumoto, Masakado; Suzuki, Masahiro; Takahashi, Masao; Hirose, Kaoru; Minagawa, Hiroko; Ohta, Michio

    2008-11-01

    Out of 68 Escherichia coli O157 field isolates tested in vitro for Shiga toxin (Stx) 2 production, 12 (17.6%) produced no or a limited amount of Stx2 (Stx 2 non- or low-producing strain; TNLP) even though all 68 possessed the stx(2) gene. The remaining 56 were Stx2 high-producing strains. The 12 TNLPs carried the q21 gene allele, which encodes a transcription antiterminator Q protein and is highly homologous to that of phi21 phage. They also carried nucleotide substitutions and insertions in the promoter region of the stx(2) gene compared with that of O157 EDL933, producing a considerable amount of Stx2. In contrast, the Stx2 high-producing strains carried the q933 gene allele, which was first reported on an stx(2) phage (933W), but not the q21 gene allele, and did not have mutations in the promoter region of the stx(2) gene. These 2 genetic characteristics, i.e., replacement of the q gene and mutation in the promoter region of the stx(2) gene, seemed to determine the amount of Stx2 produced by each strain. The TNLPs were more frequently isolated from healthy carriers than from patients (P<0.05), suggesting that TNLPs are less virulent than those with normal Stx2 production.

  1. Brachyspira (Serpulina) pilosicoli of human origin interfere with the haemolytic activity and the growth of Staphylococcus aureus beta-toxin producer.

    Science.gov (United States)

    Calderaro, A; Dettori, G; Ragni, P; Guegan, R; Arcangeletti, M C; Medici, M C; Chezzi, C

    2002-04-01

    Brachyspira (Serpulina) pilosicoli related to intestinal spirochaetosis were found to interfere in vitro with the haemolytic activity and the growth of Staphylococcus aureus beta-toxin producer. This interference was clearly appreciated because a reduction of the zone of the staphylococcal beta-toxin activity, the reduction and/or absence of cooperative haemolysis between bacteria, and the growth reduction of S. aureus were observed when B. (S.) pilosicoli were grown 72-96 hours sooner than S. aureus and after the inoculum of the latter the plates were anaerobically incubated for additional 48-72 hours. The phenomenon was more clearly observed when B. (S.) pilosicoli had a concentration of 8x10(6)-8x10(7) CFU/ml and S. aureus at a concentration ranging from 10(7) to 10(1) CFU/ml was inoculated at a distance from the streaks of B. (S.) pilosicoli ranging from 0-10 mm. When B. (S.) pilosicoli and S. aureus were inoculated at the same time and when B. (S.) pilosicoli grew 24-48 hours sooner than S. aureus only a cooperative haemolysis was observed.

  2. Heat stability of cured urea-formaldehyde resins by measuring formaldehyde emission

    Science.gov (United States)

    Shin-ichiro Tohmura; Chung-Yun Hse; Mitsuo Higuchi

    1999-01-01

    A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high tempera­tures was developed and used to assess the influence of the reaction pH at synthesis on the formaldehyde emission during cure and heat stability of the cured resins without water. Additionally, 13C-CP/MAS solid-state nuclear magnetic resonance (NMR)...

  3. Gene and antigen markers of Shiga-toxin producing E. coli from Michigan and Indiana river water: Occurrence and relation to recreational water quality criteria

    Science.gov (United States)

    Duris, J.W.; Haack, S.K.; Fogarty, L.R.

    2009-01-01

    The relation of bacterial pathogen occurrence to fecal indicator bacteria (FIB) concentrations used for recreational water quality criteria (RWQC) is poorly understood. This study determined the occurrence of Shiga-toxin producing Escherichia coli (STEC) markers and their relation to FIB concentrations in Michigan and Indiana river water. Using 67 fecal coliform (FC) bacteria cultures from 41 river sites in multiple watersheds, we evaluated the occurrence of five STEC markers: the Escherichia coli (EC) O157 antigen and gene, and the STEC virulence genes eaeA, stx1, and stx2. Simple isolations from selected FC cultures yielded viable EC O157. By both antigen and gene assays, EC O157 was detected in a greater proportion of samples exceeding rather than meeting FC RWQC (P decision-making. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  4. Presence of Potential Toxin-Producing Cyanobacteria in an Oligo-Mesotrophic Lake in Baltic Lake District, Germany: An Ecological, Genetic and Toxicological Survey

    Directory of Open Access Journals (Sweden)

    Pawan K. Dadheech

    2014-09-01

    Full Text Available Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens. The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool.

  5. Presence of potential toxin-producing cyanobacteria in an oligo-mesotrophic lake in Baltic Lake District, Germany: an ecological, genetic and toxicological survey.

    Science.gov (United States)

    Dadheech, Pawan K; Selmeczy, Géza B; Vasas, Gábor; Padisák, Judit; Arp, Wolfgang; Tapolczai, Kálmán; Casper, Peter; Krienitz, Lothar

    2014-09-29

    Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae) but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens). The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool.

  6. Effect of chitosan on the heat stability of whey protein solution as a function of pH.

    Science.gov (United States)

    Zhao, Zhengtao; Xiao, Qian

    2017-03-01

    Chitosan was reported to interact with proteins through electrostatic interactions. Their interaction was influenced by pH, which was not fully characterized. Further research on the interactions between protein and chitosan at different pH and their influence on the thermal denaturation of proteins is necessary. In this research, the effect of chitosan on the heat stability of whey protein solution at pH 4.0-6.0 was studied. At pH 4.0, a small amount chitosan was able to prevent the heat-induced denaturation and aggregation of whey protein molecules. At higher pH values (5.5 and 6.0), whey proteins complexed with chitosan through electrostatic attraction. The formation of chitosan-whey protein complexes at pH 5.5 improved the heat stability of dispersions and no precipitation could be detected up to 20 days. The dispersion with a medium amount of chitosan (chitosan:whey protein 1:5) produced the most stable particles, which had an average radius of 135 ± 14 nm and a zeta potential value of 36 ± 1 mV. In contrast, at pH 6.0 only the dispersion with a high amount of chitosan (chitosan:whey protein 1:2) showed good shelf stability up to 20 days. It was possible to produce heat-stable whey protein beverages by regulating the interaction between chitosan and whey protein molecules. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  7. Prevalence of toxin-producing Clostridium botulinum associated with the macroalga Cladophora in three Great Lakes: growth and management

    Science.gov (United States)

    Chun, Chan Lan; Kahn, Chase I.; Borchert, Andrew J.; Byappanahalli, Muruleedhara N.; Whitman, Richard L.; Peller, Julie R.; Pier, Christina; Lin, Guangyun; Johnson, Eric A.; Sadowsky, Michael J.

    2015-01-01

    The reemergence of avian botulism caused by Clostridium botulinum type E has been observed across the Great Lakes in recent years. Evidence suggests an association between the nuisance algae, Cladophoraspp., and C. botulinum in nearshore areas of the Great Lakes. However, the nature of the association between Cladophora and C. botulinum is not fully understood due, in part, to the complex food web interactions in this disease etiology. In this study, we extensively evaluated their association by quantitatively examining population size and serotypes of C. botulinum in algal mats collected from wide geographic areas in lakes Michigan, Ontario, and Erie in 2011–2012 and comparing them with frequencies in other matrices such as sand and water. A high prevalence (96%) of C. botulinum type E was observed inCladophora mats collected from shorelines of the Great Lakes in 2012. Among the algae samples containing detectable C. botulinum, the population size of C. Botulinum type E was 100–104 MPN/g dried algae, which was much greater (up to 103 fold) than that found in sand or the water column, indicating thatCladophora mats are sources of this pathogen. Mouse toxinantitoxin bioassays confirmed that the putativeC. botulinum belonged to the type E serotype. Steam treatment was effective in reducing or eliminating C. botulinum type E viable cells in Cladophora mats, thereby breaking the potential transmission route of toxin up to the food chain. Consequently, our data suggest that steam treatment incorporated with a beach cleaning machine may be an effective treatment of Cladophora-borne C. botulinum and may reduce bird mortality and human health risks.

  8. Fast detection of both O157 and non-O157 shiga-toxin producing Escherichia coli by real-time optical immunoassay.

    Science.gov (United States)

    Mondani, L; Delannoy, S; Mathey, R; Piat, F; Mercey, T; Slimani, S; Fach, P; Livache, T; Roupioz, Y

    2016-01-01

    Among bacterial pathogens involved in food-illnesses, seven serogroups (O26, O45, O103, O111, O121, O145 and O157) of Shiga-toxin producing Escherichia coli (STEC), are frequently identified. During such outbreak, and due to the perishable property of most foodstuff, the time laps for the identification of contaminated products and pathogens is thus critical to better circumvent their spread. Traditional detection methods using PCR or culture plating are time consuming and may present some limitations. In this study, we present a multiplexed immunoassay for the optical detection of most commonly enterohemorrhagic E. coli serogroups: O26, O45, O103, O111, O121, O145 and O157:H7 in a single device. The use of Surface Plasmon Resonance imaging not only enabled the label-free analysis of the samples but gave results in a real-time manner. A dedicated protocol was set up for the detection of both low contaminating bacterial concentrations of food samples (5 CFU per 25 g) and postenrichment aliquots. By combining one single device for the detection of O157 and non-O157 STEC in a label-free manner, this rapid approach may have an important economic and societal impact. This article presents a simple-to-operate immunoassay for the specific detection of Shiga-toxin producing Escherichia coli (STEC). This approach consists in the on-chip assay detection of viable cells on a specifically designed antibody microarray. By skipping any enrichment step and avoiding the use of labelling agent, this approach based on the Surface Plasmon Resonance imaging of the microarrays turns out to be much faster and more cost effective by comparison with standardized methods. © 2015 The Society for Applied Microbiology.

  9. Non-O157:H7 Shiga Toxin Producing Diarrhoeagenic Escherichia coli (STEC) in Southern India: A Tinderbox for Starting Epidemic.

    Science.gov (United States)

    Purwar, Shashank; Roy, Subrana; Metgud, Sharada

    2016-10-01

    Outbreaks due to non-O157:H7 Shiga toxin producing Escherichia coli (STEC) resulting in Haemolytic Uraemic Syndrome (HUS) have garnered much attention because of associated mortality transcending across continents and also because diarrhoea due to E.coli itself is rare in developed countries. The actual incidence of non-O157:H7 STEC in sporadic acute diarrhoea is not fully elucidated, both in developing as well as in developed countries. Due to larger extent of faecal-oral transmission in developing countries it is prudent to look for non-O157: H7 STEC in such epidemiological settings because of very high potential to spread across larger geographical regions and cause life threatening illness. To determine the extent of acute diarrhoea caused by Shiga toxin producing E. coli and measure their genotypic diversity. The study was designed as a cross-sectional study and conducted between 2009-2011 in department of Microbiology at JN Medical College Belgaum (Karnataka) and Regional Medical Research Center, Belgaum (RMRC-ICMR). Stool samples from 300 sporadic cases of acute diarrhoea were processed by microscopy, culture, for the identification of diarrhoeagenic pathogens viz. Vibrio cholera, Shigella spp., Salmonella spp. and protozoan parasites. PCR was performed for the detection of eae and stx genes in E. coli isolates. Their relatedness was determined by Random Amplification of Polymorphic DNA (RAPD). PCR detected stx along with eae in 23.2% culture isolates of E.coli isolated from diarrhoea samples. Only three isolates were identified as STEC by serology as O59, O60 and O69 serotypes. Eleven clones were detected by RAPD fingerprinting in the 46 STEC isolates. Non-O157:H7 STEC are prevalent in this region and laboratories shall look beyond O157:H7 serotype of E.coli. These isolates have potential of causing outbreaks transcending borders. Hence they shall be reported and efforts be made to identify their sources and prevent spread.

  10. Influence of calcium chelators on concentrated micellar casein solutions : from micellar structure to viscosity and heat stability

    NARCIS (Netherlands)

    Kort, de E.J.P.

    2012-01-01

    In practice it is challenging to prepare a concentrated medical product with high heat stability
    and low viscosity. Calcium chelators are often added to dairy products to improve heat stability,
    but this may increase viscosity through interactions with the casein proteins. The aim of

  11. Indolo[3,2-b]quinoline Derivatives Suppressed the Hemolytic Activity of Beta-Pore Forming Toxins, Aerolysin-Like Hemolysin Produced by Aeromonas sobria and Alpha-Hemolysin Produced by Staphylococcus aureus.

    Science.gov (United States)

    Takahashi, Eizo; Fujinami, Chiaki; Kuroda, Teruo; Takeuchi, Yasuo; Miyoshi, Shin-Ichi; Arimoto, Sakae; Negishi, Tomoe; Okamoto, Keinosuke

    2016-01-01

    In an attempt to discover inhibitory compounds against pore-forming toxins, some of the major toxins produced by bacteria, we herein examined the effects of four kinds of indolo[3,2-b]quinoline derivatives on hemolysis induced by the aerolysin-like hemolysin (ALH) of Aeromonas sobria and also by the alpha-hemolysin of Staphylococcus aureus. The results showed that hemolysis induced by ALH was significantly reduced by every derivative, while that induced by alpha-hemolysis was significantly reduced by three out of the four derivatives. However, the degrees of reduction induced by these derivatives were not uniform. Each derivative exhibited its own activity to inhibit the respective hemolysin. Compounds 1 and 2, which possessed the amino group bonding the naphthalene moiety at the C-11 position of indolo[3,2-b]quinoline, had strong inhibitory effects on the activity of ALH. Compound 4 which consisted of benzofuran and quinoline had strong inhibitory effects on the activity of alpha-hemolysin. These results indicated that the amino group bonding the naphthalene moiety of compounds 1 and 2 assisted in their ability to inhibit ALH activity, while the oxygen atom at the 10 position of compound 4 strengthened its interaction with alpha-hemolysin. These compounds also suppressed the hemolytic activity of the supernatant of A. sobria or A. hydrophila, suggesting that these compounds were effective at the site of infection of these bacteria.

  12. Fusarium dactylidis sp. nov., a novel nivalenol toxin-producing species sister to F. pseudograminearum isolated from orchard grass (Dactylis glomerata) in Oregon and New Zealand.

    Science.gov (United States)

    Aoki, Takayuki; Vaughan, Martha M; McCormick, Susan P; Busman, Mark; Ward, Todd J; Kelly, Amy; O'Donnell, Kerry; Johnston, Peter R; Geiser, David M

    2015-01-01

    The B trichothecene toxin-producing clade (B clade) of Fusarium includes the etiological agents of Fusarium head blight, crown rot of wheat and barley and stem and ear rot of maize. B clade isolates also have been recovered from several wild and cultivated grasses, including Dactylis glomerata (orchard grass or cock's foot), one of the world's most important forage grasses. Two isolates from the latter host are formally described here as F. dactylidis. Phenotypically F. dactylidis most closely resembles F. ussurianum from the Russian Far East. Both species produce symmetrical sporodochial conidia that are similar in size and curved toward both ends. However, conidia of F. ussurianum typically end in a narrow apical beak while the apical cell of F. dactylidis is acute. Fusarium dactylidis produced nivalenol mycotoxin in planta as well as low but detectable amounts of the estrogenic mycotoxin zearalenone in vitro. Results of a pathogenicity test revealed that F. dactylidis induced mild head blight on wheat. © 2015 by The Mycological Society of America.

  13. Emerging Public Health Challenges of Shiga Toxin-Producing Escherichia coli Related to Changes in the Pathogen, the Population, and the Environment.

    Science.gov (United States)

    Karmali, Mohamed A

    2017-02-01

    Emerging public health challenges of Shiga toxin (stx)-producing Escherichia coli (STEC) include the occurrence of more frequent or severe disease and risk factors shifts associated with changes, often interconnected, in the pathogen, the population, and the environment. In 3 outbreaks with heightened severity attributed to enhanced pathogen virulence, including the acquisition of an stx2 phage in 1 outbreak, population and environmental factors likely contributed significantly to disease outcomes. Evolving population risk factors that are associated with more severe disease include consumption of fresh produce, contact with STEC-contaminated environments, demographics, socioeconomic status, and immunity. Risks of increasing STEC environmental pollution are related to continued intensification of agriculture and super-shedder cattle. Mitigation strategies include surveillance and research on emerging STEC, development of effective communications and public education strategies, and improved policies and interventions to mitigate risks, including those related to the contamination of produce and the environment, using a "One Health" approach. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  14. Characterization of Shiga toxin-producing Escherichia coli isolated from ground beef collected in different socioeconomic strata markets in Buenos Aires, Argentina.

    Science.gov (United States)

    Llorente, Patricia; Barnech, Laura; Irino, Kinue; Rumi, María Valeria; Bentancor, Adriana

    2014-01-01

    Consumption of raw/undercooked ground beef is the most common route of transmission of Shiga toxin-producing E. coli (STEC). The aim of the study was to determine the STEC contamination level of the ground beef samples collected in 36 markets of different socioeconomic strata in Buenos Aires, Argentina, and the characterization of the isolated strains. Ninety-one out of 252 (36.1%) samples were stx+. Fifty-seven STEC strains were recovered. Eleven STEC strains belonged to O157 serogroup, and 46 to non-O157 serogroups. Virulence markers of the 57 STEC were stx1, 5.3% (3/57); stx2, 86.0% (49/57); stx1/stx2, 8.8% (5/57); ehxA, 61.4% (35/57); eae, 26.3% (15/57); saa, 24.6% (14/57). Shiga toxin subtypes were stx2, 31.5% (17/54); stx2c-vhb, 24.1% (13/54); stx2c-vha, 20.4% (11/54); stx2/stx2c-vha, 14.8% (8/54); stx2/stx2c-vhb, 5.6% (3/54); stx2c-vha/vhb, 3.7% (2/54). Serotypes O178:H19 and O157:H7 were prevalent. Contamination rate of STEC in all strata was high, and the highest O157 contamination was observed at low strata at several sampling rounds. Persistence of STEC was not detected. Sixteen strains (28.1%) were resistant to ampicillin, streptomycin, amikacin, or tetracycline. The STEC contamination level of ground beef could vary according to the sociocultural characteristics of the population.

  15. Genetic makeup of Shiga toxin-producing Escherichia coli in relation to clinical symptoms and duration of shedding: a microarray analysis of isolates from Swedish children.

    Science.gov (United States)

    Matussek, A; Jernberg, C; Einemo, I-M; Monecke, S; Ehricht, R; Engelmann, I; Löfgren, S; Mernelius, S

    2017-08-01

    Shiga toxin (Stx)-producing Escherichia coli (STECs) cause non-bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome, and are the primary cause of acute renal failure in children worldwide. This study investigated the correlation of genetic makeup of STEC strains as revealed by DNA microarray to clinical symptoms and the duration of STEC shedding. All STEC isolated (n = 96) from patients <10 years of age in Jönköping County, Sweden from 2003 to 2015 were included. Isolates were characterized by DNA microarray, including almost 280 genes. Clinical data were collected through a questionnaire and by reviewing medical records. Of the 96 virulence genes (including stx) in the microarray, 62 genes were present in at least one isolate. Statistically significant differences in prevalence were observed for 21 genes when comparing patients with bloody diarrhea (BD) and with non-bloody stool (18 of 21 associated with BD). Most genes encode toxins (e.g., stx2 alleles, astA, toxB), adhesion factors (i.e. espB_O157, tir, eae), or secretion factors (e.g., espA, espF, espJ, etpD, nleA, nleB, nleC, tccP). Seven genes were associated with prolonged stx shedding; the presence of three genes (lpfA, senB, and stx1) and the absence of four genes (espB_O157, espF, astA, and intI1). We found STEC genes that might predict severe disease outcome already at diagnosis. This can be used to develop diagnostic tools for risk assessment of disease outcome. Furthermore, genes associated with the duration of stx shedding were detected, enabling a possible better prediction of length of STEC carriage after infection.

  16. Variation in the Distribution of Putative Virulence and Colonization Factors in Shiga Toxin-Producing Escherichia coli Isolated from Different Categories of Cattle

    Directory of Open Access Journals (Sweden)

    Analía I. Etcheverría

    2017-04-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC are pathogens of significant public health concern. Several studies have confirmed that cattle are the main reservoir of STEC in Argentina and other countries. Although Shiga toxins represent the primary virulence factors of STEC, the adherence and colonization of the gut are also important in the pathogenesis of the bacteria. The aim of this study was to analyze and to compare the presence of putative virulence factors codified in plasmid -katP, espP, subA, stcE- and adhesins involved in colonization of cattle -efa1, iha- in 255 native STEC strains isolated from different categories of cattle from different production systems. The most prevalent gene in all strains was espP, and the less prevalent was stcE. katP was highly detected in strains isolated from young and rearing calves (33.3%, while subA was predominant in those isolated from adults (71.21%. Strains from young calves showed the highest percentage of efa1 (72.46%, while iha showed a high distribution in strains from rearing calves and adults (87.04 and 98.48% respectively. It was observed that espP and iha were widely distributed throughout all strains, whereas katP, stcE, and efa1 were more associated with the presence of eae and subA with the eae-negative strains. A great proportion of eae-negative strains were isolated from adults -dairy and grazing farms- and from rearing calves -dairy and feedlot-, while mostly of the eae-positive strains were isolated from dairy young calves. Data exposed indicate a correlation between the category of the animal and the production systems with the presence or absence of several genes implicated in adherence and virulence of STEC.

  17. Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Ground Beef Collected in Different Socioeconomic Strata Markets in Buenos Aires, Argentina

    Directory of Open Access Journals (Sweden)

    Patricia Llorente

    2014-01-01

    Full Text Available Consumption of raw/undercooked ground beef is the most common route of transmission of Shiga toxin-producing E. coli (STEC. The aim of the study was to determine the STEC contamination level of the ground beef samples collected in 36 markets of different socioeconomic strata in Buenos Aires, Argentina, and the characterization of the isolated strains. Ninety-one out of 252 (36.1% samples were stx+. Fifty-seven STEC strains were recovered. Eleven STEC strains belonged to O157 serogroup, and 46 to non-O157 serogroups. Virulence markers of the 57 STEC were stx1, 5.3% (3/57; stx2, 86.0% (49/57; stx1/stx2, 8.8% (5/57; ehxA, 61.4% (35/57; eae, 26.3% (15/57; saa, 24.6% (14/57. Shiga toxin subtypes were stx2, 31.5% (17/54; stx2c-vhb, 24.1% (13/54; stx2c-vha, 20.4% (11/54; stx2/stx2c-vha, 14.8% (8/54; stx2/stx2c-vhb, 5.6% (3/54; stx2c-vha/vhb, 3.7% (2/54. Serotypes O178:H19 and O157:H7 were prevalent. Contamination rate of STEC in all strata was high, and the highest O157 contamination was observed at low strata at several sampling rounds. Persistence of STEC was not detected. Sixteen strains (28.1% were resistant to ampicillin, streptomycin, amikacin, or tetracycline. The STEC contamination level of ground beef could vary according to the sociocultural characteristics of the population.

  18. Diversity of Shiga Toxin-Producing Escherichia coli (STEC) O26:H11 Strains Examined via stx Subtypes and Insertion Sites of Stx and EspK Bacteriophages

    Science.gov (United States)

    Bonanno, Ludivine; Loukiadis, Estelle; Mariani-Kurkdjian, Patricia; Oswald, Eric; Garnier, Lucille; Michel, Valérie

    2015-01-01

    Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen that may be responsible for severe human infections. Only a limited number of serotypes, including O26:H11, are involved in the majority of serious cases and outbreaks. The main virulence factors, Shiga toxins (Stx), are encoded by bacteriophages. Seventy-four STEC O26:H11 strains of various origins (including human, dairy, and cattle) were characterized for their stx subtypes and Stx phage chromosomal insertion sites. The majority of food and cattle strains possessed the stx1a subtype, while human strains carried mainly stx1a or stx2a. The wrbA and yehV genes were the main Stx phage insertion sites in STEC O26:H11, followed distantly by yecE and sbcB. Interestingly, the occurrence of Stx phages inserted in the yecE gene was low in dairy strains. In most of the 29 stx-negative E. coli O26:H11 strains also studied here, these bacterial insertion sites were vacant. Multilocus sequence typing of 20 stx-positive or stx-negative E. coli O26:H11 strains showed that they were distributed into two phylogenetic groups defined by sequence type 21 (ST21) and ST29. Finally, an EspK-carrying phage was found inserted in the ssrA gene in the majority of the STEC O26:H11 strains but in only a minority of the stx-negative E. coli O26:H11 strains. The differences in the stx subtypes and Stx phage insertion sites observed in STEC O26:H11 according to their origin might reflect that strains circulating in cattle and foods are clonally distinct from those isolated from human patients. PMID:25819955

  19. Escherichia coli O104:H4 Pathogenesis: an Enteroaggregative E. coli/Shiga Toxin-Producing E. coli Explosive Cocktail of High Virulence.

    Science.gov (United States)

    Navarro-Garcia, Fernando

    2014-12-01

    A major outbreak caused by Escherichia coli of serotype O104:H4 spread throughout Europe in 2011. This large outbreak was caused by an unusual strain that is most similar to enteroaggregative E. coli (EAEC) of serotype O104:H4. A significant difference, however, is the presence of a prophage encoding the Shiga toxin, which is characteristic of enterohemorrhagic E. coli (EHEC) strains. This combination of genomic features, associating characteristics from both EAEC and EHEC, represents a new pathotype. The 2011 E. coli O104:H4 outbreak of hemorrhagic diarrhea in Germany is an example of the explosive cocktail of high virulence and resistance that can emerge in this species. A total of 46 deaths, 782 cases of hemolytic-uremic syndrome, and 3,128 cases of acute gastroenteritis were attributed to this new clone of EAEC/EHEC. In addition, recent identification in France of similar O104:H4 clones exhibiting the same virulence factors suggests that the EHEC O104:H4 pathogen has become endemically established in Europe after the end of the outbreak. EAEC strains of serotype O104:H4 contain a large set of virulence-associated genes regulated by the AggR transcription factor. They include, among other factors, the pAA plasmid genes encoding the aggregative adherence fimbriae, which anchor the bacterium to the intestinal mucosa (stacked-brick adherence pattern on epithelial cells). Furthermore, sequencing studies showed that horizontal genetic exchange allowed for the emergence of the highly virulent Shiga toxin-producing EAEC O104:H4 strain that caused the German outbreak. This article discusses the role these virulence factors could have in EAEC/EHEC O104:H4 pathogenesis.

  20. Development of a multiplex PCR assay for detection of Shiga toxin-producing Escherichia coli, enterohemorrhagic E. coli, and enteropathogenic E. coli strains.

    Science.gov (United States)

    Botkin, Douglas J; Galli, Lucía; Sankarapani, Vinoth; Soler, Michael; Rivas, Marta; Torres, Alfredo G

    2012-01-01

    Escherichia coli O157:H7 and other pathogenic E. coli strains are enteric pathogens associated with food safety threats and which remain a significant cause of morbidity and mortality worldwide. In the current study, we investigated whether enterohemorrhagic E. coli (EHEC), Shiga toxin-producing E. coli (STEC), and enteropathogenic E. coli (EPEC) strains can be rapidly and specifically differentiated with multiplex PCR (mPCR) utilizing selected biomarkers associated with each strain's respective virulence genotype. Primers were designed to amplify multiple intimin (eae) and long polar fimbriae (lpfA) variants, the bundle-forming pilus gene bfpA, and the Shiga toxin-encoding genes stx1 and stx2. We demonstrated consistent amplification of genes specific to the prototype EHEC O157:H7 EDL933 (lpfA1-3, lpfA2-2, stx1, stx2, and eae-γ) and EPEC O127:H6 E2348/69 (eae-α, lpfA1-1, and bfpA) strains using the optimized mPCR protocol with purified genomic DNA (gDNA). A screen of gDNA from isolates in a diarrheagenic E. coli collection revealed that the mPCR assay was successful in predicting the correct pathotype of EPEC and EHEC clones grouped in the distinctive phylogenetic disease clusters EPEC1 and EHEC1, and was able to differentiate EHEC1 from EHEC2 clusters. The assay detection threshold was 2 × 10(4) CFU per PCR reaction for EHEC and EPEC. mPCR was also used to screen Argentinean clinical samples from hemolytic uremic syndrome and diarrheal patients, resulting in 91% sensitivity and 84% specificity when compared to established molecular diagnostic procedures. In conclusion, our mPCR methodology permitted differentiation of EPEC, STEC and EHEC strains from other pathogenic E. coli; therefore, the assay becomes an additional tool for rapid diagnosis of these organisms.

  1. Development of 11-Plex MOL-PCR Assay for the Rapid Screening of Samples for Shiga Toxin-Producing Escherichia coli

    Directory of Open Access Journals (Sweden)

    Travis A Woods

    2016-08-01

    Full Text Available Strains of Shiga toxin-producing Escherichia coli (STEC are a serious threat to the public health, with approximately half of the STEC related food-borne illnesses attributable to contaminated beef. We developed an assay that was able to screen samples for several important STEC associated serogroups (O26, O45, O103, O104, O111, O121, O145, O157 and three major virulence factors (eae, stx1, stx2 in a rapid and multiplexed format using the Multiplex oligonucleotide ligation-PCR (MOL-PCR assay chemistry. This assay detected unique STEC DNA signatures and was meant to be used on samples from various sources related to beef production, providing a multiplex and high-throughput complement to the multiplex PCR assays currently in use. Multiplex oligonucleotide ligation-PCR (MOL-PCR is a nucleic acid-based assay chemistry that relies on flow cytometry/image cytometry and multiplex microsphere arrays for the detection of nucleic acid-based signatures present in target agents. The STEC MOL-PCR assay provided greater than 90% analytical specificity across all sequence markers designed when tested against panels of DNA samples that represent different STEC serogroups and toxin gene profiles. This paper describes the development of the 11-plex assay and the results of its validation. This highly multiplexed, but more importantly dynamic and adaptable screening assay allows inclusion of additional signatures as they are identified in relation to public health. As the impact of STEC associated illness on public health is explored additional information on classification will be needed on single samples; thus, this assay can serve as the backbone for a complex screening system.

  2. The ecological stoichiometry of toxins produced by harmful cyanobacteria: an experimental test of the carbon-nutrient balance hypothesis

    NARCIS (Netherlands)

    Van de Waal, D.B.; Verspagen, J.M.H.; Lürling, M.; Van Donk, E.; Visser, P.M.; Huisman, J.

    2009-01-01

    The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of

  3. The ecological stoichiometry of toxins produced by harmful cyanobacteria: An experimental test of the carbon-nutrient balance hypothesis

    NARCIS (Netherlands)

    van de Waal, D.B.; Verspagen, J.M.H.; Lürling, M.; van Donk, E.; Visser, P.M.; Huisman, J.

    2009-01-01

    The elemental composition of primary producers reflects the availability of light, carbon and nutrients in their environment. According to the carbon-nutrient balance hypothesis, this has implications for the production of secondary metabolites. To test this hypothesis, we investigated a family of

  4. Control of the Biofilms Formed by Curli- and Cellulose-Expressing Shiga Toxin-Producing Escherichia coli Using Treatments with Organic Acids and Commercial Sanitizers.

    Science.gov (United States)

    Park, Yoen Ju; Chen, Jinru

    2015-05-01

    Biofilms are a mixture of bacteria and extracellular products secreted by bacterial cells and are of great concern to the food industry because they offer physical, mechanical, and biological protection to bacterial cells. This study was conducted to quantify biofilms formed by different Shiga toxin-producing Escherichia coli (STEC) strains on polystyrene and stainless steel surfaces and to determine the effectiveness of sanitizing treatments in control of these biofilms. STEC producing various amounts of cellulose (n = 6) or curli (n = 6) were allowed to develop biofilms on polystyrene and stainless steel surfaces at 28°C for 7 days. The biofilms were treated with 2% acetic or lactic acid and manufacturer-recommended concentrations of acidic or alkaline sanitizers, and residual biofilms were quantified. Treatments with the acidic and alkaline sanitizers were more effective than those with the organic acids for removing the biofilms. Compared with their counterparts, cells expressing a greater amount of cellulose or curli formed more biofilm mass and had greater residual mass after sanitizing treatments on polystyrene than on stainless steel. Research suggests that the organic acids and sanitizers used in the present study differed in their ability to control biofilms. Bacterial surface components and cell contact surfaces can influence both biofilm formation and the efficacy of sanitizing treatments. These results provide additional information on control of biofilms formed by STEC.

  5. Risk Factors for Salmonella, Shiga Toxin-Producing Escherichia coli and Campylobacter Occurrence in Primary Production of Leafy Greens and Strawberries

    Directory of Open Access Journals (Sweden)

    Siele Ceuppens

    2015-08-01

    Full Text Available The microbiological sanitary quality and safety of leafy greens and strawberries were assessed in the primary production in Belgium, Brazil, Egypt, Norway and Spain by enumeration of Escherichia coli and detection of Salmonella, Shiga toxin-producing E. coli (STEC and Campylobacter. Water samples were more prone to containing pathogens (54 positives out of 950 analyses than soil (16/1186 and produce on the field (18/977 for leafy greens and 5/402 for strawberries. The prevalence of pathogens also varied markedly according to the sampling region. Flooding of fields increased the risk considerably, with odds ratio (OR 10.9 for Salmonella and 7.0 for STEC. A significant association between elevated numbers of generic E. coli and detection of pathogens (OR of 2.3 for STEC and 2.7 for Salmonella was established. Generic E. coli was found to be a suitable index organism for Salmonella and STEC, but to a lesser extent for Campylobacter. Guidelines on frequency of sampling and threshold values for E. coli in irrigation water may differ from region to region.

  6. Risk Factors for Salmonella, Shiga Toxin-Producing Escherichia coli and Campylobacter Occurrence in Primary Production of Leafy Greens and Strawberries

    Science.gov (United States)

    Ceuppens, Siele; Johannessen, Gro S.; Allende, Ana; Tondo, Eduardo César; El-Tahan, Fouad; Sampers, Imca; Jacxsens, Liesbeth; Uyttendaele, Mieke

    2015-01-01

    The microbiological sanitary quality and safety of leafy greens and strawberries were assessed in the primary production in Belgium, Brazil, Egypt, Norway and Spain by enumeration of Escherichia coli and detection of Salmonella, Shiga toxin-producing E. coli (STEC) and Campylobacter. Water samples were more prone to containing pathogens (54 positives out of 950 analyses) than soil (16/1186) and produce on the field (18/977 for leafy greens and 5/402 for strawberries). The prevalence of pathogens also varied markedly according to the sampling region. Flooding of fields increased the risk considerably, with odds ratio (OR) 10.9 for Salmonella and 7.0 for STEC. A significant association between elevated numbers of generic E. coli and detection of pathogens (OR of 2.3 for STEC and 2.7 for Salmonella) was established. Generic E. coli was found to be a suitable index organism for Salmonella and STEC, but to a lesser extent for Campylobacter. Guidelines on frequency of sampling and threshold values for E. coli in irrigation water may differ from region to region. PMID:26295251

  7. Distinct Expression of Immunoglobulin-Binding Proteins in Shiga Toxin-Producing Escherichia coli Implicates High Protein Stability and a Characteristic Phenotype

    Science.gov (United States)

    Rubin, Dennis; Zhang, Wenlan; Karch, Helge; Kuczius, Thorsten

    2017-01-01

    Several immunoglobulin-binding proteins of Escherichia coli (Eib) have been isolated from both non-pathogenic and pathogenic E. coli strains. Shiga toxin (Stx)-producing E. coli (STEC) contain eibG either as a single gene or in combination with eibC, while other E. coli strains harbour single or multiple eib genes. The Eib proteins bind human immunoglobulins in a non-immune manner and contribute to bacterial chain-like adherence to human epithelial cells. In this study, the EibG expression in several STEC strains was analysed under different environmental conditions. STEC produced high levels of EibG in complex media and lower levels in low-grade and minimal media under static growth conditions. This characteristic was independent on the Eib subtypes. Microscopically, EibG-expressing STEC exhibited chain formation and aggregation in all employed media, while aggregates were only visible after growth in complex medium. Once expressed, EibG proteins demonstrate high stability during prolonged incubation. Our findings indicate that the regulation of the expression of Eib proteins is highly complex, although the protein levels vary among STEC strains. However, positive upregulation conditions generally result in distinct phenotypes of the isolates. PMID:28468281

  8. Evaluation of the performance of the IQ-check kits and the USDA microbiology laboratory guidebook methods for detection of Shiga Toxin-Producing E. coli (STEC) and STEC and Salmonella simultaneously in ground beef

    Science.gov (United States)

    Aims: To evaluate the performance of the IQ-Check kits and the USDA Microbiology Laboratory Guidebook (MLG) methods for detection of the top 7 Shiga toxin-producing E. coli (STEC) (O157:H7, O26, O45, O103, O111, O121, and O145) in ground beef and both STEC and Salmonella in co-inoculated samples. M...

  9. Evaluation of a novel antimicrobial solution and its potential for control E. coli O157:H7, non-O157:H7 shiga toxin-producing E. coli, Salmononella spp., and Listeria monocytogenes on beef

    Science.gov (United States)

    The goal of this study was to evaluate the efficacy of a novel antimicrobial solution made with chitosan, lauric arginate ester, and organic acids on Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and non-O157 shiga toxin-producing E. coli cocktails and to test its potential to b...

  10. The effect of regions of interest and spectral pre-processing on the detection of non-O157 shiga-toxin producing escherichia coli serogroups on agar media by hyperspectral imaging

    Science.gov (United States)

    Food borne infection caused by Shiga toxin-producing Escherichia coli (STEC) is a major worldwide health concern. The best known STEC serotype is E. coli O157:H7, which can be easily identified when cultured on sorbitol-MacConkey (SMAC) agar. Recently, six non-O157 STEC serotypes have been found t...

  11. Detection of Shiga toxin-producing Escherichia coli (STEC) O157:H7, O26, O45, O103, O111, O121, and O145, and Salmonella in retail raw ground beef using the DuPont BAX system

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) and Salmonella are food-borne pathogens commonly associated with beef, and reliable methods are needed to determine their prevalence in beef and to ensure food safety. Retail ground beef was tested for the presence of E. coli O157:H7, STEC serogroups O2...

  12. Latex agglutination assays for detection and of non-O157 Shiga toxin-producing E. coli serogroups O26, O45, O103, O111, O121 and O145

    Science.gov (United States)

    Latex agglutination assays were developed for the top six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups utilizing polyclonal antibodies. Rabbit antisera were affinity purified through Protein A/G columns and the isolated immunoglobulins (IgG) were covalently immobilized onto pol...

  13. Role of Cellulose and Colanic Acid in Attachment of Shiga Toxin-Producing Escherichia coli to Lettuce and Spinach in Different Water Hardness Environments.

    Science.gov (United States)

    Lee, Chi-Ching; Chen, Jinru; Frank, Joseph F

    2015-08-01

    This study investigated the role of extracellular cellulose production by Shiga toxin-producing Escherichia coli (STEC) on attachment to lettuce and spinach in different water hardness environments. Two cellulose-producing wild-type STEC strains, 19 (O5:H-) and 49 (O103:H2), and their cellulose-deficient derivatives were used. Strain 49 also produced colanic acid as a constituent of its extracellular polymeric substances. Attached cells were determined by plate counts on the surface and cut edge of the leaves after an attachment period of 2 h at 4°C. Hydrophobicity and surface charge of the cells were determined. Strain 49 attached at levels 0.3 and 0.6 log greater to the surface and 0.9 and 0.4 log greater to the cut edges of spinach compared to strain 19 for both wild-type and cellulose-deficient cells (P > 0.05). Cellulose-producing cells attached more to the surface of lettuce but not of spinach than did cellulose-deficient cells. However, more cellulose-deficient cells attached (at levels 0.66 and 0.3 log greater) to the cut edge of lettuce (representing damaged tissue) than did cellulose-proficient cells (P > 0.05). Colanic acid production was associated with cell surfaces of low hydrophobicity. There was a decreasing level of attachment for the colanic acid-producing strain when water hardness increased from 200 to 1,000 pm on lettuce and spinach leaf surfaces, but no effects were seen for other cells. This decreased attachment was associated with a more negative surface charge. Cells that produced colanic acid were less hydrophobic and exhibited greater attachment to the surface and cut edge of spinach when compared to cells that did not produce colanic acid. Attachment of colanic acid-producing cells to leafy green surfaces was enhanced in higher water hardness environments. These data indicate that attachment of E. coli O157:H7 to leafy greens involves multiple mechanisms that are influenced by the type of leafy green, damage to the leaf, and the water

  14. Microalgal toxin(s): characteristics and importance

    African Journals Online (AJOL)

    Prokaryotic and eukaryotic microalgae produce a wide array of compounds with biological activities. These include antibiotics, algicides, toxins, pharmaceutically active compounds and plant growth regulators. Toxic microalgae, in this sense, are common only among the cyanobacteria and dinoflagellates. The microalgal ...

  15. From farm to table: follow-up of Shiga toxin-producing Escherichia coli throughout the pork production chain in Argentina

    Directory of Open Access Journals (Sweden)

    Rocío eColello

    2016-02-01

    Full Text Available Pigs are important reservoirs of Shiga toxin-producing Escherichia coli (STEC. The entrance of these strains into the food chain implies a risk to consumers because of the severity of hemolytic uremic syndrome. This study reports the prevalence and characterization of Shiga toxin-producing Escherichia coli (STEC throughout the pork production chain. From 764 samples, 31 (4.05% were stx positive by PCR screening. At farms, 2.86% of samples were stx positive; at slaughter, 4.08% of carcasses were stx positive and at boning rooms, 6% of samples were stx positive. These percentages decreased in pork meat ready for sale at sales markets (4.59%. From positive samples, 50 isolates could be characterized. At farms 37.5% of the isolates carried stx1/stx2 genes, 37.5% possessed stx2e and 25%, carried only stx2. At slaughter we detected 50% of isolates positive for stx2, 33% for stx2e and 16% for stx1/stx2. At boning rooms 59% of the isolates carried stx1/stx2, 14% stx2e and 5% stx1/stx2/stx2e. At retail markets 66% of isolates were positive for stx2, 17% stx2e and 17% stx1/stx2. For the other virulence factors, ehxA and saa were not detected and eae gene was detected in 12% of the isolates. Concerning putative adhesins, agn43 was detected in 72%, ehaA in 26%, aida in 8% and iha in 6% of isolates. The strains were typed into 14 E. coli O groups (O1, O2, O8, O15, O20, O35, O69, O78, O91, O121, O138, O142, O157, O180 and ten H groups (H9, H10, H16, H21, H26, H29, H30, H32, H45, H46. This study reports the prevalence and characterization of STEC strains through the chain pork suggesting the vertical transmission. STEC contamination originates in the farms and is transferred from pigs to carcasses in the slaughter process and increase in meat pork at boning rooms and sales markets. These results highlight the need to implement an integrated STEC control system based on good management practices on the farm and critical control point systems in the food chain.

  16. Characterization of Shiga toxin-producing Escherichia coli O130:H11 and O178:H19 isolated from dairy cows

    Science.gov (United States)

    Fernández, Daniel; Krüger, Alejandra; Polifroni, Rosana; Bustamante, Ana V.; Sanso, A. Mariel; Etcheverría, Analía I.; Lucchesi, Paula M. A.; Parma, Alberto E.; Padola, Nora L.

    2013-01-01

    Shiga toxin-producing E. coli (STEC) are isolated from human patients with bloody diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS). In the last years, the infections with non-O157 serotypes are increasing their frequency of association with human disease. STEC produce Shiga toxin (Stx) and other virulence factors that could contribute to human pathogenesis. Cattle are the main reservoir and the transmission to humans is through the consumption of undercooked meat, non-pasteurized dairy products, and vegetables or water contaminated with feces. We have previously determined that O130:H11 and O178:H19 serotypes were the most prevalent in dairy cows from Argentina. In the present study, 37 and 25 STEC isolates from dairy cows belonging to O130:H11 and O178:H19 serotypes, respectively, were characterized regarding to their cytotoxicity on Vero cells, stx subtypes, presence of sab and typing by multiple-locus variable-number tandem repeat analysis (MLVA). All strains demonstrated a cytotoxic effect, and in O130:H11 isolates, stx2EDL933 was the predominant subtype. In O178:H19 isolates the main stx2 subtype was stx2vha. The sab gene was detected in 65 and 24% of the isolates belonging to O130:H11 and O178:H19, respectively. Only one MLVA profile was identified among the O130:H11 isolates meanwhile 10 MLVA profiles were detected among the O178:H19 isolates which were grouped in two main clusters. In conclusion, our data show that O130:H11 and O178:H19 STEC isolates encode virulence factors associated with severe human disease and both serotypes should be considered for routinely testing. Our subtyping experiments showed that isolates could be distinguished based on the stx2 subtype and the presence/absence of sab gene, and for isolates belonging to O178:H19, also when the MLVA type was considered. However, MLVA subtyping of O130:H11 isolates will require the development of more specific markers. PMID:23483233

  17. Identification of Shiga toxin-producing (STEC) and enteropathogenic (EPEC) Escherichia coli in diarrhoeic calves and comparative genomics of O5 bovine and human STEC.

    Science.gov (United States)

    Fakih, I; Thiry, D; Duprez, J-N; Saulmont, M; Iguchi, A; Piérard, D; Jouant, L; Daube, G; Ogura, Y; Hayashi, T; Taminiau, B; Mainil, J G

    2017-04-01

    Escherichia coli producing Shiga toxins (Stx) and the attaching-effacing (AE) lesion (AE-STEC) are responsible for (bloody) diarrhoea in humans and calves while the enteropathogenic E. coli (EPEC) producing the AE lesion only cause non-bloody diarrhoea in all mammals. The purpose of this study was (i) to identify the pathotypes of enterohaemolysin-producing E. coli isolated between 2009 and 2013 on EHLY agar from less than 2 month-old diarrhoeic calves with a triplex PCR targeting the stx1, stx2, eae virulence genes; (ii) to serotype the positive isolates with PCR targeting the genes coding for ten most frequent and pathogenic human and calf STEC O serogroups; and (iii) to compare the MLSTypes and virulotypes of calf and human O5 AE-STEC after Whole Genome Sequencing using two server databases (www.genomicepidemiology.org). Of 233 isolates, 206 were triplex PCR-positive: 119 AE-STEC (58%), 78 EPEC (38%) and 9 STEC (4%); and the stx1+eae+ AE-STEC (49.5%) were the most frequent. Of them, 120 isolates (84% of AE-STEC, 23% of EPEC, 22% of STEC) tested positive with one O serogroup PCR: 57 for O26 (47.5%), 36 for O111 (30%), 10 for O103 (8%) and 8 for O5 (7%) serogroups. The analysis of the draft sequences of 15 O5 AE-STEC could not identify any difference correlated to the host. As a conclusion, (i) the AE-STEC associated with diarrhoea in young calves still belong to the same serogroups as previously (O5, O26, O111) but the O103 serogroup may be emerging, (ii) the O5 AE-STEC from calves and humans are genetically similar. Copyright © 2016. Published by Elsevier B.V.

  18. Staphylococcus aureus toxins.

    Science.gov (United States)

    Otto, Michael

    2014-02-01

    Staphylococcus aureus is a dangerous pathogen that causes a variety of severe diseases. The virulence of S. aureus is defined by a large repertoire of virulence factors, among which secreted toxins play a preeminent role. Many S. aureus toxins damage biological membranes, leading to cell death. In particular, S. aureus produces potent hemolysins and leukotoxins. Among the latter, some were recently identified to lyse neutrophils after ingestion, representing an especially powerful weapon against bacterial elimination by innate host defense. Furthermore, S. aureus secretes many factors that inhibit the complement cascade or prevent recognition by host defenses. Several further toxins add to this multi-faceted program of S. aureus to evade elimination in the host. This review will give an overview over S. aureus toxins focusing on recent advances in our understanding of how leukotoxins work in receptor-mediated or receptor-independent fashions. Published by Elsevier Ltd.

  19. [Hygienic-sanitary quality in abattoirs from Tucuman province, Argentina. Detection, isolation and characterization of Shiga toxin-producing Escherichia coli].

    Science.gov (United States)

    Pérez Terrazzino, Gabriela B; Condorí, Marina S; López Campo, Alejandro; Vega, Silvia; Carbonari, Carolina; Chinen, Isabel; Rivas, Marta; de Castillo, Marta C; Jure, María A

    Cattle are the main reservoir of Shiga toxin-producing Escherichia coli (STEC), and the strategies to prevent the transmission of these microorganisms are concentrated in the slaughtering plant. The aim of this study was to evaluate the hygienic-sanitary quality and the frequency of detection of STEC in beef carcasses in abattoirs from Tucuman province. Two hundred and seventy four beef carcass sponges were processed; the count of generic E. coli was marginal in 9 (3,3%) of them. Escherichia coli O157 was isolated in 4 (1,4%) samples; 2 of which were characterized as stx2c(vh-a)/eae/ehxA whereas the other 2 were non-toxigenic strains. Non-O157 E. coli ONT:H49, stx2a/ehxA/saa was isolated from 1 sample (0,4%). In this work the quality of the analyzed product indicates that the good practices of manufacture are fulfilled in slaughtering facilities in Tucumán province. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. Surveillance of Virulence Markers and Antibiotic Resistance of Shiga toxin Producing E.coli O157:H7 Strains from Meats Purchase in Shiraz

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    Mohammad Kargar

    2011-09-01

    Full Text Available Background: Shiga toxin Producing Escherichia coli O157:H7 is a common pathogen in cattle, which occasional causes some human disease. This bacterium can potentially contaminate meat and clinical cases of E.coli O157:H7 infections are often associated with consumption of undercooked ground beef. Methods: In this cross-sectional study 122 samples of ground meat were collected and after enrichment in specific culture media and evaluation sorbitol fermentation and their β-glucoronidase activity, the isolation of E.coli O157:H7 strains have been confirmed with specific antisera. Then virulence genes verotoxin, intimin and hemolysin with multiplex PCR and antibiotic resistance strains with disk diffusion method have been tested. Results: Out of specimens that have been supplied, 119 sorbitol negative colonies isolated which 3 strains O157:H7 (2.45% with specific antisera confirmed. Out of considered virulence genes, in two cases of these samples (1.64% the stx1 and eaeA genes were seen and also 2 isolated bacteria had resistance to erythromycin, tetracycline, ampicillin, penicillin, clindamicin, cefixime, novobiocin, and gentamicin antibiotics. Conclusion: As this organism lives in intestines of healthy cattle, preventive measures on cattle farms and during meat processing are necessary.

  1. Transmission of shiga toxin-producing Escherichia coli O104:H4 at a family party possibly due to contamination by a food handler, Germany 2011.

    Science.gov (United States)

    Diercke, M; Kirchner, M; Claussen, K; Mayr, E; Strotmann, I; Frangenberg, J; Schiffmann, A; Bettge-Weller, G; Arvand, M; Uphoff, H

    2014-01-01

    We investigated a cluster of shiga toxin-producing Escherichia coli (STEC) O104:H4 infections after a family party during a large STEC O104:H4 outbreak in Germany. To identify the vehicle we conducted a retrospective cohort study. Stool samples of party guests, and food and environmental samples from the catering company were tested for STEC. We defined cases as party guests with gastrointestinal symptoms and laboratory-confirmed STEC infection. We found 23 cases among 71 guests. By multivariable analysis consumption of salmon [odds ratio (OR) 15, 95% confidence interval (CI) 2.3-97], herb cream (OR 6.5, 95% CI 1.3-33) and bean salad (OR 6.1, 95% CI 1.4-26) were associated with STEC infection. STEC O104:H4 was detected in samples of bell pepper and salmon. The food handler developed STEC infection. Our results point towards transmission via several food items contaminated by a food handler. We recommend regular education of food handlers emphasizing their role in transmitting infectious diseases.

  2. Seasonal prevalence of potentially positive non-O157 Shiga toxin-producing Escherichia coli (STEC) bovine hides and carcasses in Costa Rica.

    Science.gov (United States)

    Chaves, Byron D; Echeverry, Alejandro; García, Lyda G; Brashears, M Todd; Miller, Markus F; Brashears, Mindy M

    2015-12-01

    The prevalence of potentially positive Shiga toxin-producing Escherichia coli (STEC) bovine hides and carcasses in three abattoirs in Costa Rica was estimated. Two export facilities (A and B) and one non-export establishment (C) were visited during the dry and rainy seasons of 2013. Swabs of hides pre-eviscerated and treated (180-220 peroxyacetic acid spray) carcasses were tested for the potential presence of STEC serogroups O26, O45, O103, O111, O121, and O145. The prevalence on hides during the rainy season was 86.7, 96.7 and 96.7% for facilities A, B, and C, respectively. During the dry season, the prevalence on hides was significantly lower in plants A and B (40% and 26.7%, respectively), but was marginally associated with the season in plant C (76.7%, P=0.0523). The prevalence of non-O157 STEC markers on treated carcasses was low (0 to 3.3%), suggesting that all plants were effective in minimizing the target non-O157 STEC in beef destined for export and for domestic consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Molecular investigation of tRNA genes integrity and its relation to pathogenicity islands in Shiga toxin-producing Escherichia coli (STEC strains

    Directory of Open Access Journals (Sweden)

    Rogério Carlos Novais

    2004-01-01

    Full Text Available tRNA genes are known target sites for the integration of pathogenicity islands (PAI and other genetic elements, such as bacteriophages, into bacterial genome. In most STEC (Shiga toxin-producing Escherichia coli, the PAI called LEE (locus of enterocyte effacement is related to bacterial virulence and is mostly associated to the tRNA genes selC and pheU. In this work, we first investigated the relationship of LEE with tRNA genes selC and pheU in 43 STEC strains. We found that 28 strains (65% had a disrupted selC and/or pheU. Three of these strains (637/1, 650/5 and 654/3 were chosen to be submitted to a RAPD-PCR technique modified by the introduction of specific primers (corresponding to the 5'end of genes selC and pheU into the reaction, which we called "anchored RAPD-PCR". The PCR fragments obtained were transferred onto membranes, and those fragments which hybridized to selC and pheU probes were isolated. One of these fragments from strain 637/1 was partially sequenced. An 85-nucleotide sequence was found to be similar to the cfxA2 gene that encodes a beta-lactamase and is part of transposon Tn4555, a pathogenicity island originally integrated into the Bacteroides genome.

  4. Detection of Shiga Toxin-Producing Strains of Escherichia coli (O157:H7 isolated from specimens of urinary and stool by Multiplex-PCR method

    Directory of Open Access Journals (Sweden)

    seyed mohammad nayeb Nayeb Aghaee

    2006-06-01

    Full Text Available Background: Infection of shiga toxin-producing Strains of Escherichia coli has some other dangerous and deadly effects such as hemolytic uremic syndrome (HUS in addition to diarrhea. Its diagnosis is difficult and there is no information on It's incidence in Iran. The goal of this study is to evaluate and detect shiga toxinproducing strains of E. coli isolated from urinary and stool specimens by multiplex- PCR method. Materials and Methods: One hundred samples out of 500 collected samples were screened. The selected samples have more chance of heaving different kinds of O157. After DNA extraction from the isolated strains, the multiplex PCR reaction for both stx1 and stx2 genes performed and consequently amplicons were examined by agarose gel electrophoresis. Samples were analyzed after painting by ethidium bromide. Findings: Only 3 cases (3% of the studied sample were positive for the presence of STEC. All three cases were related to stx2. Two of them were related from feces samples and one of them was isolated from the urine samples. Conclusion: Although it seems that the incidence and prevalence of gastrointestinal infections by STEC are low in Iran, But because of the serious complications of the STEC infection such as HUS and HC and failure of detection of these strains by routine methods it is necessary to use molecular and serological diagnostic methods, especially in childhood clinics for recognizing doubtful cases.

  5. [Isolation of Shiga-toxin-producing Escherichia coli strains during a gastrointestinal outbreak at a day care center in Mar del Plata City].

    Science.gov (United States)

    Gomez, D; Miliwebsky, E; Silva, A; Deza, N; Zotta, C; Cotella, O; Martínez Espinosa, E; Chinen, I; Fernández Pascua, C; Rivas, M

    2005-01-01

    From October 15 to November 8, 2003, a gastrointestinal outbreak occurred at a day care center in a Hospital in Mar del Plata City. Fourteen out of 80 (17.5%) children, mean age 23.6 +/- 13.9 months, and the mother of one of them had diarrhea. One case developed hemolytic uremic syndrome. No conclusive evidence of the origin of the outbreak was found, but the epidemic curve suggested person-to-person spread. The usual practices at the place where infant milk formula was prepared at the day care center, together with the inadequate infrastructure conditions and hygiene practices at the kitchen of the hospital, were considered risk factors. One case had Shiga toxin-producing Escherichia coli (STEC) O103:H2 infection and other STEC O26:H11. The duration of shedding for the child with O26:H11 infection was 37 days. In the other symptomatic children, the pathogen was not recovered from fecal samples collected 6 or more days after the onset of the illness. This emphasizes that the collection of early samples is necessary to recover STEC strains. In order to prevent and control enteric diseases in day care facilities the following measures are necessary: optimal hygiene standards, early case reporting, and exclusion of those who remain culture-positive.

  6. Growth and Survival of Acid-Resistant and Non-Acid-Resistant Shiga-Toxin-Producing Escherichia coli Strains during the Manufacture and Ripening of Camembert Cheese

    Directory of Open Access Journals (Sweden)

    M. P. Montet

    2009-01-01

    Full Text Available Growth and survival of acid-resistant (AR and non-acid-resistant (NAR Shiga-toxin-producing Escherichia coli (STEC strains were investigated during the manufacture and ripening of microfiltered milk Camembert cheeses. The induction of acid resistance of the STEC strains in cheeses was also studied. Six different mixtures of AR and/or NAR STEC strains were inoculated separately into microfiltered milk at a level of 103 CFU mL−1. The STEC counts (AR and NAR initially increased by 1 to 2 log⁡10 CFU g−1 during cheese-making. Thereafter, the populations stabilized during salting/drying and then decreased during the early stages of ripening. Exposing the STEC strains in artificially inoculated cheeses to simulated gastric fluid (SGF - pH: 2.0 reduced the number of NAR strains to undetectable levels within 40 minutes, versus 120 minutes for the AR STEC strains. AR and NAR STEC were able to survive during the manufacture and ripening of Camembert cheese prepared from microfiltered milk with no evidence of induced acid tolerance in NAR STEC strains.

  7. Growth and Survival of Acid-Resistant and Non-Acid-Resistant Shiga-Toxin-Producing Escherichia coli Strains during the Manufacture and Ripening of Camembert Cheese

    Science.gov (United States)

    Montet, M. P.; Jamet, E.; Ganet, S.; Dizin, M.; Miszczycha, S.; Dunière, L.; Thevenot, D.; Vernozy-Rozand, C.

    2009-01-01

    Growth and survival of acid-resistant (AR) and non-acid-resistant (NAR) Shiga-toxin-producing Escherichia coli (STEC) strains were investigated during the manufacture and ripening of microfiltered milk Camembert cheeses. The induction of acid resistance of the STEC strains in cheeses was also studied. Six different mixtures of AR and/or NAR STEC strains were inoculated separately into microfiltered milk at a level of 103 CFU mL−1. The STEC counts (AR and NAR) initially increased by 1 to 2 log10 CFU g−1 during cheese-making. Thereafter, the populations stabilized during salting/drying and then decreased during the early stages of ripening. Exposing the STEC strains in artificially inoculated cheeses to simulated gastric fluid (SGF - pH: 2.0) reduced the number of NAR strains to undetectable levels within 40 minutes, versus 120 minutes for the AR STEC strains. AR and NAR STEC were able to survive during the manufacture and ripening of Camembert cheese prepared from microfiltered milk with no evidence of induced acid tolerance in NAR STEC strains. PMID:20016668

  8. Impact of antibiotics on the intestinal microbiota and on the treatment of Shiga-toxin-producing Escherichia coli and Salmonella infections.

    Science.gov (United States)

    Szych, Jolanta; Wołkowicz, Tomasz; La Ragione, Roberto; Madajczak, Grzegorz

    2014-01-01

    This review evaluates the current literature based on the impact of antibiotics on the intestinal microbiota and the critical role of intestinal bacteria in controlling infection and subsequent clinical disease caused by STEC and Salmonella, and the transmissibility of these important pathogens.A number of studies have indicated that antibiotic therapy could result in unexpected changes in the clinical picture of disease. This is observed, for example, in the case of infections associated with Shiga-toxin-producing Escherichia coli (STEC), when antibiotics used in treatment of the disease may increase the risk of hemolytic uremic syndrome (HUS) and thus fatal outcomes. In the case of such infections, treatment with antibiotics is usually discouraged. The use of antibiotics could cause also undesirable changes in the intestinal microbial flora and prolonged pathogen shedding, which is observed in the case of Salmonella infections. Inappropriate antibiotic therapy can result in Salmonella remaining in the host's cells (intracellular) and thus resulting in further asymptomatic carriage and a further complication is the development of resistance.

  9. Characterization of a chromosomally integrated luxCDABE marker for investigation of shiga toxin-producing Escherichia coli O91:H21 shedding in cattle

    Science.gov (United States)

    Hong, Yingying; Mathew, Alan G.

    2011-06-01

    Shiga toxin-producing Escherichia coli (STEC) O91:H21 has been recognized as a potential life-threatening foodborne pathogen and is commonly involved in human infections in European countries. Fecal shedding of the organism by cattle is considered to be the ultimate source for contaminations. Studies examining STEC shedding patterns often include inoculation of strains carrying antibiotic resistance makers for identifiable recovery. However, indigenous intestinal microflora exhibiting similar antibiotic resistance patterns can confound such studies. Such was the case in a study by our group when attempting to characterize shedding patterns of O91:H21 in calves. A chromosomally integrated bioluminescence marker using a luxCDABE cassette from Photorhabdus luminescens was developed in O91:H21 to overcome such shortcomings of antibiotic resistance markers during animal challenge experiment. The marker was validated in various aspects and was shown to have no impact on metabolic reactions, isotype virulence gene patterns, cost to growth, and additionally demonstrated high in vitro stability. Together, the results indicated that a chromosomally integrated luxCDABE based marker may be a superior system for the study of STEC colonization and shedding in cattle.

  10. Public health approach to detection of non-O157 Shiga toxin-producing Escherichia coli: summary of two outbreaks and laboratory procedures.

    Science.gov (United States)

    Schaffzin, J K; Coronado, F; Dumas, N B; Root, T P; Halse, T A; Schoonmaker-Bopp, D J; Lurie, M M; Nicholas, D; Gerzonich, B; Johnson, G S; Wallace, B J; Musser, K A

    2012-02-01

    Routine laboratory testing may not detect non-O157 Shiga toxin-producing Escherichia coli (STEC) reliably. Active clinical, epidemiological, environmental health, and laboratory collaboration probably influence successful detection and study of non-O157 STEC infection. We summarized two outbreak investigations in which such coordinated efforts identified non-O157 STEC disease and led to effective control measures. Outbreak 1 involved illness associated with consuming unpasteurized apple cider from a local orchard. Public health personnel were notified by a local hospital; stool specimens from ill persons contained O111 STEC. Outbreak 2 involved bloody diarrhoea at a correctional facility. Public health personnel were notified by the facility infection control officer; O45 STEC was the implicated agent. These reports highlight the ability of non-O157 STEC to cause outbreaks and demonstrate that a coordinated effort by clinicians, infection-control practitioners, clinical diagnostic laboratorians, and public health personnel can lead to effective identification, investigation, and prevention of non-O157 STEC disease.

  11. Assessment of Consumer Exposure to Salmonella spp., Campylobacter spp., and Shiga Toxin-Producing Escherichia coli in Meat Products at Retail in the City of Sao Paulo, Brazil.

    Science.gov (United States)

    Ristori, Christiane Asturiano; Rowlands, Ruth Estela Gravato; Martins, Cecília Geraldes; Barbosa, Maria Luisa; Dos Santos, Luis Fernando; Jakabi, Miyoko; de Melo Franco, Bernadette Dora Gombossy

    2017-08-01

    Meat products may be vehicles of bacterial pathogens to humans, and Salmonella spp., Campylobacter spp., and Shiga toxin-producing Escherichia coli (STEC) are the most relevant. The aim of this study was to generate data on prevalence of these three pathogens in 552 samples of meat products (hot dogs, pork sausages, raw ground beef, and raw chicken legs) sold at retail in the city of Sao Paulo, Brazil. Salmonella spp. was detected in 5.8% (32/552) of samples, comprising pork sausages 62.5% (20/32) and chicken legs 37.5% (12/32). The counts of Salmonella spp. were low, ranging from < 0.3 to 9.3 × 10 most probable number per gram and the most frequent serovars were Salmonella Typhimurium (28.1%), Salmonella I 4,[5],12:i:- (15.6%), Salmonella Enteritidis (12.5%), Salmonella Derby, and Salmonella Brandenburg (9.4%). Campylobacter spp. was detected in 33 samples (6.0%), comprising chicken legs (82%) and ground beef (18%). All samples were negative for STEC. These results suggest that meat products when subjected to inadequate cooking and/or cross-contamination with other products ready for consumption can lead to occurrence of outbreaks, highlighting the risks associated with them.

  12. Phenotypic characteristics, virulence profile and genetic relatedness of O157 Shiga toxin-producing Escherichia coli isolated in Brazil and other Latin American countries.

    Science.gov (United States)

    Bastos, Flávia C; Vaz, Tânia Mara I; Irino, Kinue; Guth, Beatriz Ernestina C

    2006-12-01

    Thirty-eight Shiga toxin-producing Escherichia coli (STEC) O157:H7/H(-) strains isolated from human infections, cattle and foods in Brazil and in some other Latin American countries were compared with regard to several phenotypic and genotypic characteristics. The genetic relatedness of the strains was also determined by pulsed-field gel electrophoresis (PFGE). Similar biochemical behaviour was identified, regardless of the origin and country of the strains. Most (89.5%) strains were sensitive to the antimicrobial agents tested, but resistance to at least one drug was observed among bovine strains. Although a diversity of stx genotypes was identified, most (77.8%) of the human strains harboured stx(2) or stx(2)stx(2c(2vha)), whereas stx(2c(2vha)) prevailed (64.2%) among strains isolated from cattle. stx(1) and stx(1)stx(2c(2vha)) were the genotypes identified less frequently, and occurred exclusively among strains isolated from food and cattle, respectively. Despite differences in the stx genotypes, all strains carried eae-gamma, efa1, ehx, iha, lpf(O157) and toxB sequences. Many closely related subgroups (more than 80% of similarity) were identified by PFGE, and the presence of a particular O157:H7 STEC clone more related to human infections in Brazil, as well as a common origin for some strains isolated from different sources and countries in Latin America can be suggested.

  13. Association of clustered regularly interspaced short palindromic repeat (CRISPR) elements with specific serotypes and virulence potential of shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Toro, Magaly; Cao, Guojie; Ju, Wenting; Allard, Marc; Barrangou, Rodolphe; Zhao, Shaohua; Brown, Eric; Meng, Jianghong

    2014-02-01

    Shiga toxin-producing Escherichia coli (STEC) strains (n = 194) representing 43 serotypes and E. coli K-12 were examined for clustered regularly interspaced short palindromic repeat (CRISPR) arrays to study genetic relatedness among STEC serotypes. A subset of the strains (n = 81) was further analyzed for subtype I-E cas and virulence genes to determine a possible association of CRISPR elements with potential virulence. Four types of CRISPR arrays were identified. CRISPR1 and CRISPR2 were present in all strains tested; 1 strain also had both CRISPR3 and CRISPR4, whereas 193 strains displayed a short, combined array, CRISPR3-4. A total of 3,353 spacers were identified, representing 528 distinct spacers. The average length of a spacer was 32 bp. Approximately one-half of the spacers (54%) were unique and found mostly in strains of less common serotypes. Overall, CRISPR spacer contents correlated well with STEC serotypes, and identical arrays were shared between strains with the same H type (O26:H11, O103:H11, and O111:H11). There was no association identified between the presence of subtype I-E cas and virulence genes, but the total number of spacers had a negative correlation with potential pathogenicity (P CRISPR-cas system and potential virulence needs to be determined on a broader scale, and the biological link will need to be established.

  14. Real-time genomic investigation underlying the public health response to a Shiga toxin-producing Escherichia coli O26:H11 outbreak in a nursery.

    Science.gov (United States)

    Moran-Gilad, J; Rokney, A; Danino, D; Ferdous, M; Alsana, F; Baum, M; Dukhan, L; Agmon, V; Anuka, E; Valinsky, L; Yishay, R; Grotto, I; Rossen, J W A; Gdalevich, M

    2017-10-01

    Shiga toxin-producing Escherichia coli (STEC) is a significant cause of gastrointestinal infection and the haemolytic-uremic syndrome (HUS). STEC outbreaks are commonly associated with food but animal contact is increasingly being implicated in its transmission. We report an outbreak of STEC affecting young infants at a nursery in a rural community (three HUS cases, one definite case, one probable case, three possible cases and five carriers, based on the combination of clinical, epidemiological and laboratory data) identified using culture-based and molecular techniques. The investigation identified repeated animal contact (animal farming and petting) as a likely source of STEC introduction followed by horizontal transmission. Whole genome sequencing (WGS) was used for real-time investigation of the incident and revealed a unique strain of STEC O26:H11 carrying stx2a and intimin. Following a public health intervention, no additional cases have occurred. This is the first STEC outbreak reported from Israel. WGS proved as a useful tool for rapid laboratory characterization and typing of the outbreak strain and informed the public health response at an early stage of this unusual outbreak.

  15. Outbreak of Shiga toxin-producing Escherichia coli O111:H8 infections among attendees of a high school cheerleading camp.

    Science.gov (United States)

    Brooks, John T; Bergmire-Sweat, David; Kennedy, Malinda; Hendricks, Kate; Garcia, Marianne; Marengo, Lisa; Wells, Joy; Ying, Michelle; Bibb, William; Griffin, Patricia M; Hoekstra, Robert M; Friedman, Cindy R

    2004-01-15

    Few US clinical laboratories screen stool specimens for Shiga toxin-producing Escherichia coli (STEC) other than E. coli O157. An outbreak of STEC O111:H8 infections indistinguishable from E. coli O157:H7 at a youth camp highlights the need to improve non-O157 STEC surveillance. Interviews of 521 (80%) of 650 attendees revealed 55 (11%) were ill; 2 developed hemolytic-uremic syndrome. Illness was associated with consuming salad during the camp's first lunch meal (hazard ratio [HR], 4.68; P<.01), consuming ice provided in barrels on the camp's final day (HR, 3.41; P<.01), eating cob corn (HR, 3.22; P<.01), and eating a dinner roll (HR, 2.82; P<.01). Cultures of 2 of 11 stools yielded E. coli O111:H8. Results of serologic testing and additional stool cultures demonstrated no evidence of infection with other bacterial pathogens, including E. coli O157, and supported infection with E. coli O111. Clinical laboratories should routinely screen suspect specimens for non-O157 STEC and should serotype and report Shiga-positive isolates.

  16. Detection of Shiga toxin-producing and other diarrheagenic Escherichia coli by the BioFire FilmArray® Gastrointestinal Panel in human fecal samples.

    Science.gov (United States)

    De Rauw, K; Detemmerman, L; Breynaert, J; Piérard, D

    2016-09-01

    The purpose of this investigation was the evaluation of the performance of the BioFire FilmArray® Gastrointestinal (FA-GI) Panel, a multiplexed molecular stool screening assay, for the detection of diarrheagenic Escherichia coli (DEC), with emphasis on Shiga toxin-producing E. coli (STEC). A dilution series of 12 STEC reference strains was tested with the FA-GI Panel to assess the analytical sensitivity. A total of 389 patient samples were analyzed with the FA-GI Panel and confirmation of the detected DEC was attempted with an in-house culture-based polymerase chain reaction (PCR) method. All Shiga toxin genes, except the one encoding Stx2f, were detected in bacterial dilutions ranging from 10(4) to 10(2) colony-forming units (CFU)/ml. eae + stx2f + STEC was misclassified as enteropathogenic E. coli (EPEC). Different sensitivities for various gene targets present in one isolate led to differing identifications depending on the concentration. Using the in-house method as a reference, the FA-GI Panel had a sensitivity of 90.6 % [confidence interval (CI) 75.0 %-98.0 %] and a specificity of 97.2 % (CI 94.9 %-98.6 %) for STEC detection in feces. At least one DEC was reported in 35.5 % (171/389) of the patient specimens, with EPEC being the most prevalent (n = 71). Only 59.7 % of the detected DEC could be confirmed, presumably because the comparator method was not applied directly on feces. The FA-GI Panel could not detect the stx2f subtype, misclassified certain pathogens, and the high detection rate of EPEC needs further investigation. Nevertheless, we believe that this sensitive and convenient system will prove to be an invaluable tool for the rapid diagnosis of most DEC infections, but culturing of the detected microorganisms should always be attempted.

  17. Emerging types of Shiga toxin-producing E. coli (STEC) O178 present in cattle, deer, and humans from Argentina and Germany

    Science.gov (United States)

    Miko, Angelika; Rivas, Marta; Bentancor, Adriana; Delannoy, Sabine; Fach, Patrick; Beutin, Lothar

    2014-01-01

    More than 400 serotypes of Shiga toxin-producing Escherichia coli (STEC) have been implicated in outbreaks and sporadic human diseases. In recent years STEC strains belonging to serogroup O178 have been commonly isolated from cattle and food of bovine origin in South America and Europe. In order to explore the significance of these STEC strains as potential human pathogens, 74 German and Argentinean E. coli O178 strains from animals, food and humans were characterized phenotypically and investigated for their serotypes, stx-genotypes and 43 virulence-associated markers by a real-time PCR-microarray. The majority (n = 66) of the O178 strains belonged to serotype O178:H19. The remaining strains divided into O178:H7 (n = 6), O178:H10 (n = 1), and O178:H16 (n = 1). STEC O178:H19 strains were mainly isolated from cattle and food of bovine origin, but one strain was from a patient with hemolytic uremic syndrome (HUS). Genotyping of the STEC O178:H19 strains by pulsed-field gel electrophoresis revealed two major clusters of genetically highly related strains which differ in their stx-genotypes and non-Stx putative virulence traits, including adhesins, toxins, and serine-proteases. Cluster A-strains including the HUS-strain (n = 35) carried genes associated with severe disease in humans (stx2a, stx2d, ehxA, saa, subAB1, lpfAO113, terE combined with stx1a, espP, iha). Cluster B-strains (n = 26) showed a limited repertoire of virulence genes (stx2c, pagC, lpfAO113, espP, iha). Among O178:H7 strains isolated from deer meat and patients with uncomplicated disease a new STEC variant was detected that is associated with the genotype stx1c/stx2b/ehxA/subAB2/espI/[terE]/espP/iha. None of the STEC O178 strains was positive for locus of enterocyte effacement (LEE)- and nle-genes. Results indicate that STEC O178:H19 strains belong to the growing group of LEE-negative STEC that should be considered with respect to their potential to cause diseases in humans. PMID:24987616

  18. Multiplex real-time PCR assays for detection of eight Shiga toxin-producing Escherichia coli in food samples by melting curve analysis.

    Science.gov (United States)

    Singh, Prashant; Mustapha, Azlin

    2015-12-23

    Shiga toxin-producing Escherichia coli (STEC) are pathogenic strains of E. coli that can cause bloody diarrhea and kidney failure. Seven STEC serogroups, O157, O26, O45, O103, O111, O121 and O145 are responsible for more than 71% of the total infections caused by this group of pathogens. All seven serogroups are currently considered as adulterants in non-intact beef products in the U.S. In this study, two multiplex melt curve real-time PCR assays with internal amplification controls (IACs) were standardized for the detection of eight STEC serogroups. The first multiplex assay targeted E. coli serogroups O145, O121, O104, and O157; while the second set detected E. coli serogroups O26, O45, O103 and O111. The applicability of the assays was tested using 11 different meat and produce samples. For food samples spiked with a cocktail of four STEC serogroups with a combined count of 10 CFU/25 g food, all targets of the multiplex assays were detected after an enrichment period of 6h. The assays also worked efficiently when 325 g of food samples were spiked with 10 CFU of STECs. The assays are not dependent on fluorescent-labeled probes or immunomagnetic beads, and can be used for the detection of eight STEC serogroups in less than 11h. Routine preliminary screening of STECs in food samples is performed by testing for the presence of STEC virulence genes. The assays developed in this study can be useful as a first- or second-tier test for the identification of the eight O serogroup-specific genes in suspected food samples. Copyright © 2015. Published by Elsevier B.V.

  19. Genomics study of the exposure effect of Gymnodinium catenatum, a paralyzing toxin producer, on Crassostrea gigas' defense system and detoxification genes.

    Directory of Open Access Journals (Sweden)

    Norma García-Lagunas

    Full Text Available BACKGROUND: Crassostrea gigas accumulates paralytic shellfish toxins (PST associated with red tide species as Gymnodinium catenatum. Previous studies demonstrated bivalves show variable feeding responses to toxic algae at physiological level; recently, only one study has reported biochemical changes in the transcript level of the genes involved in C. gigas stress response. PRINCIPAL FINDINGS: We found that 24 h feeding on toxic dinoflagellate cells (acute exposure induced a significant decrease in clearance rate and expression level changes of the genes involved in antioxidant defense (copper/zinc superoxide dismutase, Cu/Zn-SOD, cell detoxification (glutathione S-transferase, GST and cytochrome P450, CPY450, intermediate immune response activation (lipopolysaccharide and beta glucan binding protein, LGBP, and stress responses (glutamine synthetase, GS in Pacific oysters compared to the effects with the non-toxic microalga Isochrysis galbana. A sub-chronic exposure feeding on toxic dinoflagellate cells for seven and fourteen days (30×10³ cells mL⁻¹ showed higher gene expression levels. A significant increase was observed in Cu/Zn-SOD, GST, and LGBP at day 7 and a major increase in GS and CPY450 at day 14. We also observed that oysters fed only with G. catenatum (3×10³ cells mL⁻¹ produced a significant increase on the transcription level than in a mixed diet (3×10³ cells mL⁻¹ of G. catenatum+0.75×10⁶ cells mL⁻¹ I. galbana in all the analyzed genes. CONCLUSIONS: Our results provide gene expression data of PST producer dinoflagellate G. catenatum toxic effects on C. gigas, a commercially important bivalve. Over expressed genes indicate the activation of a potent protective mechanism, whose response depends on both cell concentration and exposure time against these toxic microalgae. Given the importance of dinoflagellate blooms in coastal environments, these results provide a more comprehensive overview of how oysters respond to

  20. Mexican unpasteurised fresh cheeses are contaminated with Salmonella spp., non-O157 Shiga toxin producing Escherichia coli and potential uropathogenic E. coli strains: A public health risk.

    Science.gov (United States)

    Guzman-Hernandez, Rosa; Contreras-Rodriguez, Araceli; Hernandez-Velez, Rosa; Perez-Martinez, Iza; Lopez-Merino, Ahide; Zaidi, Mussaret B; Estrada-Garcia, Teresa

    2016-11-21

    Fresh cheeses are a main garnish of Mexican food. Consumption of artisanal fresh cheeses is very common and most of them are made from unpasteurised cow milk. A total of 52 fresh unpasteurised cheeses of five different types were purchased from a variety of suppliers from Tabasco, Mexico. Using the most probable number method, 67% and 63% of samples were positive for faecal coliforms and E. coli, respectively; revealing their low microbiological quality. General hygienic conditions and practices of traditional cheese manufacturers were poor; most establishments had unclean cement floors, all lacked windows and doors screens, and none of the food-handlers wore aprons, surgical masks or bouffant caps. After analysing all E. coli isolates (121 strains) for the presence of 26 virulence genes, results showed that 9 (17%) samples were contaminated with diarrheagenic E. coli strains, 8 harboured non-O157 Shiga toxin producing E. coli (STEC), and one sample contained both STEC and diffusely adherent E. coli strains. All STEC strains carried the stx1 gene. Potential uropathogenic E. coli (UPEC) strains were isolated from 15 (29%) samples; the most frequent gene combination was fimA-agn43. Two samples were contaminated with Salmonella. The results demonstrated that unpasteurised fresh cheeses produced in Tabasco are of poor microbiological quality and may frequently harbour foodborne pathogens. Food safety authorities in Mexico need to conduct more rigorous surveillance of fresh cheeses. Furthermore, simple and inexpensive measures as establishing programs emphasizing good hand milking practices and hygienic manufacturing procedures may have a major effect on improving the microbiological quality of these food items. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Pertussis toxin

    Energy Technology Data Exchange (ETDEWEB)

    Sekura, R.D.; Moss, J.; Vaughan, M.

    1985-01-01

    This book contains 13 selections. Some of the titles are: Genetic and Functional Studies of Pertussis Toxin Substrates; Effect of Pertussis Toxin on the Hormonal Responsiveness of Different Tissues; Extracellular Adenylate Cyclase of Bordetella pertussis; and GTP-Regulatory Proteins are Introcellular Messagers: A Model for Hormone Action.

  2. Polyamine toxins

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Jensen, Lars S; Vogensen, Stine B

    2005-01-01

    Polyamine toxins, isolated from spiders and wasps, have been used as pharmacological tools for the study of ionotropic receptors, but their use have so far been hampered by their lack of selectivity. In this mini-review, we describe how careful synthetic modification of native polyamine toxins have...

  3. Botulinum toxin.

    Science.gov (United States)

    The National Institutes of Health Consensus Development Conference on Clinical Use of Botulinum Toxin brought together neurologists, ophthalmologists, otolaryngologists, speech pathologists, and other health care professionals as well as the public to address: the mechanisms of action of botulinum toxin, the indications and contraindications for botulinum toxin treatment, the general principles of technique of injection and handling for its safe and effective use, and the short-term and long-term side effects and complications of therapy. Following 2 days of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared their consensus statement. Among their findings, the panel recommended that (1) botulinum toxin therapy is safe and effective for treating strabismus, blepharospasm, hemifacial spasm, adductor spasmodic dysphonia, jaw-closing oromandibular dystonia, and cervical dystonia; (2) botulinum toxin is not curative in chronic neurological disorders; (3) the safety of botulinum toxin therapy during pregnancy, breast feeding, and chronic use during childhood is unknown; (4) the long-term effects of chronic treatment with botulinum toxin remain unknown; and (5) botulinum toxin should be administered by committed interdisciplinary teams of physicians and related health care professionals with appropriate instrumentation. The full text of the consensus panel's statement follows.

  4. Toxin Plasmids of Clostridium perfringens

    Science.gov (United States)

    Li, Jihong; Adams, Vicki; Bannam, Trudi L.; Miyamoto, Kazuaki; Garcia, Jorge P.; Uzal, Francisco A.; Rood, Julian I.

    2013-01-01

    SUMMARY In both humans and animals, Clostridium perfringens is an important cause of histotoxic infections and diseases originating in the intestines, such as enteritis and enterotoxemia. The virulence of this Gram-positive, anaerobic bacterium is heavily dependent upon its prolific toxin-producing ability. Many of the ∼16 toxins produced by C. perfringens are encoded by large plasmids that range in size from ∼45 kb to ∼140 kb. These plasmid-encoded toxins are often closely associated with mobile elements. A C. perfringens strain can carry up to three different toxin plasmids, with a single plasmid carrying up to three distinct toxin genes. Molecular Koch's postulate analyses have established the importance of several plasmid-encoded toxins when C. perfringens disease strains cause enteritis or enterotoxemias. Many toxin plasmids are closely related, suggesting a common evolutionary origin. In particular, most toxin plasmids and some antibiotic resistance plasmids of C. perfringens share an ∼35-kb region containing a Tn916-related conjugation locus named tcp (transfer of clostridial plasmids). This tcp locus can mediate highly efficient conjugative transfer of these toxin or resistance plasmids. For example, conjugative transfer of a toxin plasmid from an infecting strain to C. perfringens normal intestinal flora strains may help to amplify and prolong an infection. Therefore, the presence of toxin genes on conjugative plasmids, particularly in association with insertion sequences that may mobilize these toxin genes, likely provides C. perfringens with considerable virulence plasticity and adaptability when it causes diseases originating in the gastrointestinal tract. PMID:23699255

  5. Simultaneous direct detection of Shiga-toxin producing Escherichia coli (STEC) strains by optical biosensing with oligonucleotide-functionalized gold nanoparticles

    Science.gov (United States)

    Quintela, Irwin A.; de Los Reyes, Benildo G.; Lin, Chih-Sheng; Wu, Vivian C. H.

    2015-01-01

    A simultaneous direct detection of Shiga-toxin producing strains of E. coli (STEC; ``Big Six'' - O26, O45, O103, O111, O121, and O145) as well as O157 strains by optical biosensing with oligonucleotide-functionalized gold nanoparticles (AuNPs) was developed. Initially, conserved regions of stx genes were amplified by asymmetric polymerase chain reaction (asPCR). Pairs of single stranded thiol-modified oligonucleotides (30-mer) were immobilized onto AuNPs and used as probes to capture regions of stx1 (119-bp) and/or stx2 (104-bp) genes from STEC strains. DNA samples from pure cultures and food samples were sandwich hybridized with AuNP-oligo probes at optimal conditions (50 °C, 30 min). A complex was formed from the hybridization of AuNP-probes and target DNA fragments that retained the initial red color of the reaction solutions. For non-target DNA, a color change from red to purplish-blue was observed following an increase in salt concentration, thus providing the basis of simultaneous direct colorimetric detection of target DNA in the samples. Enrichment and pooling systems were incorporated to efficiently process a large number of food samples (ground beef and blueberries) and detection of live targets. The detection limit was properties of AuNPs as a low-cost and simple approach yet with high specificity for simultaneous detection of STEC strains.A simultaneous direct detection of Shiga-toxin producing strains of E. coli (STEC; ``Big Six'' - O26, O45, O103, O111, O121, and O145) as well as O157 strains by optical biosensing with oligonucleotide-functionalized gold nanoparticles (AuNPs) was developed. Initially, conserved regions of stx genes were amplified by asymmetric polymerase chain reaction (asPCR). Pairs of single stranded thiol-modified oligonucleotides (30-mer) were immobilized onto AuNPs and used as probes to capture regions of stx1 (119-bp) and/or stx2 (104-bp) genes from STEC strains. DNA samples from pure cultures and food samples were sandwich

  6. Ability of Shiga toxin-producing Escherichia coli and Salmonella spp. to survive in a desiccation model system and in dry foods.

    Science.gov (United States)

    Hiramatsu, Reiji; Matsumoto, Masakado; Sakae, Kenji; Miyazaki, Yutaka

    2005-11-01

    In order to determine desiccation tolerances of bacterial strains, the survival of 58 diarrheagenic strains (18 salmonellae, 35 Shiga toxin-producing Escherichia coli [STEC], and 5 shigellae) and of 15 nonpathogenic E. coli strains was determined after drying at 35 degrees C for 24 h in paper disks. At an inoculum level of 10(7) CFU/disk, most of the salmonellae (14/18) and the STEC strains (31/35) survived with a population of 10(3) to 10(4) CFU/disk, whereas all of the shigellae (5/5) and the majority of the nonpathogenic E. coli strains (9/15) did not survive (the population was decreased to less than the detection limit of 10(2) CFU/disk). After 22 to 24 months of subsequent storage at 4 degrees C, all of the selected salmonellae (4/4) and most of the selected STEC strains (12/15) survived, keeping the original populations (10(3) to 10(4) CFU/disk). In contrast to the case for storage at 4 degrees C, all of 15 selected strains (5 strains each of Salmonella spp., STEC O157, and STEC O26) died after 35 to 70 days of storage at 25 degrees C and 35 degrees C. The survival rates of all of these 15 strains in paper disks after the 24 h of drying were substantially increased (10 to 79 times) by the presence of sucrose (12% to 36%). All of these 15 desiccated strains in paper disks survived after exposure to 70 degrees C for 5 h. The populations of these 15 strains inoculated in dried foods containing sucrose and/or fat (e.g., chocolate) were 100 times higher than those in the dried paper disks after drying for 24 h at 25 degrees C.

  7. Multiplex real-time PCR and culture methods for detection of Shiga toxin-producing Escherichia coli and Salmonella Thompson in strawberries, a lettuce mix and basil.

    Science.gov (United States)

    Delbeke, S; Ceuppens, S; Holvoet, K; Samuels, E; Sampers, I; Uyttendaele, M

    2015-01-16

    An appropriate approach of high throughput multi-screening was verified for Shiga toxin-producing Escherichia coli (STEC) and Salmonella spp. in strawberries, lettuce and basil. Sample replicates were inoculated with STEC O157 or O26 and Salmonella Thompson (ca. 10-70, 100-700 and 1000-7000 cfu/25 g) and analysed after 1 and 5 days of storage (strawberries and lettuce at 7 °C and basil at 10 °C). After 18-24 h of enrichment at 37 °C in buffered peptone water, detection was performed using the GeneDisc multiplex PCR (stx1, stx2, eae and iroB genes) and selective culture media for isolation of STEC (with immunomagnetic separation (IMS)) and Salmonella spp. in parallel. After 1 day, the pathogenic strains were recovered from all samples for all inoculum levels, whereas reduced detection rates of STEC O157 and S. Thompson were observed after 5 days of storage in case of strawberries, in particular for the lowest inoculums level, suggesting superior survival potential for STEC O26. Overall, this study indicates the ability of PCR based screening methods for reproducible multi-detection of low numbers (10-70 cfu/25 g) of STEC and Salmonella in this type of foods. However, for the basil samples, PCR needed twofold dilution of the DNA extract to overcome inhibition. It was noted that on several occasions growth of competitive microbiota obstructed finding presumptive colonies on the selective agar media, whereas the use of an additional agar medium such as CHROMagar STEC (without IMS) improved recovery rate of STEC. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Tellurite resistance profiles and performance of different chromogenic agars for detection of non-O157 Shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Fan, Ruyue; Bai, Xiangning; Fu, Shanshan; Xu, Yanmei; Sun, Hui; Wang, Hong; Xiong, Yanwen

    2018-02-02

    Shiga toxin-producing Escherichia coli (STEC) are globally important food-borne pathogens. The isolation of non-O157 STEC is a significant public health challenge due to the dramatic diversity of their phenotypes and genotypes. In the present study, 476 non-O157 STEC strains representing 95 different O-serogroups were used to evaluate tellurite resistance and the performance of 12 different chromogenic agars. Of 476 strains, only 108 (22.7%) strains showed the minimal inhibitory concentration (MIC) values for potassium tellurite being higher than 4μg/ml, and 96 (20.2%) strains harbored intact ter genes cluster. The presence of ter genes was significantly correlated with tellurite resistance. Six commercial chromogenic agars (TBX, MAC, SMAC, Rainbow® Agar O157, CHROMagar™ ECC, and Fluorocult O157) supported the growth of all strains. However, CT-SMAC, CHROMagar™ O157, and CHROMagar™ STEC agars exhibited 12.2%, 31.1%, and 38.0% of growth inhibition, respectively. Furthermore, 4.6%, 33.2%, and 45.0% of strains were inhibited on RBA-USDA, RBA-NT, and BCM O157 agar media. Variations in tellurite resistance and colony appearance might result in discrepant performance of non-O157 STEC recovery from different chromogenic agars. Using inclusive agars or less selective agar in combination with highly selective agar should be suggested to recover most non-O157 STEC strains, which would increase the probability of recovering STECs from complex background microflora. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. O-antigen and virulence profiling of Shiga toxin-producing Escherichia coli by a rapid and cost-effective DNA microarray colorimetric method

    Directory of Open Access Journals (Sweden)

    Beatriz eQuiñones

    2012-05-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC is a leading cause of foodborne illness worldwide. The present study developed the use of DNA microarrays with the ampliPHOX colorimetric method to rapidly detect and genotype STEC strains. A low-density 30-mer oligonucleotide DNA microarray was designed to target O-antigen gene clusters of eleven E. coli serogroups (O26, O45, O91, O103, O104, O111, O113, O121, O128, O145 and O157 that have been associated with the majority of STEC infections. In addition, the DNA microarray targeted eleven virulence genes, encoding adhesins, cytotoxins, proteases, and receptor proteins, which have been implicated in conferring increased ability to cause disease for STEC. Results from the validation experiments demonstrated that this microarray-based colorimetric method allowed for a rapid and accurate genotyping of STEC reference strains from environmental and clinical sources and from distinct geographical locations. Positive hybridization signals were detected only for probes targeting serotype and virulence genes known to be present in the STEC reference strains. Quantification analysis indicated that the mean pixel intensities of the signal for probes targeting O-antigen or virulence genes were at least three times higher when compared to the background. Furthermore, this microarray-based colorimetric method was then employed to genotype a group of E. coli isolates from watershed sediment and animal fecal samples that were collected from an important region for leafy-vegetable production in the central coast of California. The results indicated an accurate identification of O-type and virulence genes in the tested isolates and confirmed that the ampliPHOX colorimetric method with low density DNA microarrays enabled a fast assessment of the virulence potential of STEC using low-cost reagents and instrumentation.

  10. Characterization of novel bacteriophage phiC119 capable of lysing multidrug-resistant Shiga toxin-producing Escherichia coli O157:H7

    Directory of Open Access Journals (Sweden)

    Luis Amarillas

    2016-09-01

    Full Text Available Background Shiga toxin-producing Escherichia coli (STEC is one of the most common and widely distributed foodborne pathogens that has been frequently implicated in gastrointestinal and urinary tract infections. Moreover, high rates of multiple antibiotic-resistant E. coli strains have been reported worldwide. Due to the emergence of antibiotic-resistant strains, bacteriophages are considered an attractive alternative to biocontrol pathogenic bacteria. Characterization is a preliminary step towards designing a phage for biocontrol. Methods In this study, we describe the characterization of a bacteriophage designated phiC119, which can infect and lyse several multidrug-resistant STEC strains and some Salmonella strains. The phage genome was screened to detect the stx-genes using PCR, morphological analysis, host range was determined, and genome sequencing were carried out, as well as an analysis of the cohesive ends and identification of the type of genetic material through enzymatic digestion of the genome. Results Analysis of the bacteriophage particles by transmission electron microscopy showed that it had an icosahedral head and a long tail, characteristic of the family Siphoviridae. The phage exhibits broad host range against multidrug-resistant and highly virulent E. coli isolates. One-step growth experiments revealed that the phiC119 phage presented a large burst size (210 PFU/cell and a latent period of 20 min. Based on genomic analysis, the phage contains a linear double-stranded DNA genome with a size of 47,319 bp. The phage encodes 75 putative proteins, but lysogeny and virulence genes were not found in the phiC119 genome. Conclusion These results suggest that phage phiC119 may be a good biological control agent. However, further studies are required to ensure its control of STEC and to confirm the safety of phage use.

  11. Isolation of atypical enteropathogenic Escherichia coli and Shiga toxin 1 and 2f-producing Escherichia coli from avian species in India.

    Science.gov (United States)

    Farooq, S; Hussain, I; Mir, M A; Bhat, M A; Wani, S A

    2009-06-01

    To study the prevalence and characterize atypical enteropathogenic Escherichia coli (EPEC) and Shiga toxin producing E. coli (STEC) in avian species in India. Two hundred and twelve faecal samples collected from 62 chickens, 50 ducks and 100 pigeons were investigated for the presence of stx(1), stx(2), eae and ehxA virulence genes by multiplex PCR. In all, 42 E. coli isolates (25 chicken, 2 duck and 15 pigeon) possessed at least one virulence gene. Out of these, nine (4.24%) isolates were STEC and 33 (15.56%) were EPEC. All isolates from duck and chicken were EPEC while among 15 pigeon isolates nine (60%) were STEC and six (40%) were EPEC. Among the STEC isolates four each carried stx(1) or stx(2) and one possessed both stx(1) and stx(2). Subtype analysis of stx revealed the presence of stx(2f) in four STEC isolates. None of the STEC isolates carried stx(1c), stx(2c), stx(2d) or stx(2e). Isolates carrying stx(2f) demonstrated vero cell toxicity. One each belonged to serogroup O17 and O78, while one was rough and the other untypeable. All EPEC isolates were atypical as they lacked bfpA. This appears to be the first report of detection of stx(2f) from India. The study established the presence of stx(1) and stx(2f) containing E. coli in pigeons and atypical EPEC in poultry in India. Pigeons might serve as vectors for transmission of STEC to environment and humans. Taking into account the close contact between fanciers and pigeons, these findings warrant a more critical appraisal of these zoonotic pathogens in pigeons and humans.

  12. Isolation and selection of coliphages as potential biocontrol agents of enterohemorrhagic and Shiga toxin-producing E. coli (EHEC and STEC) in cattle.

    Science.gov (United States)

    Dini, C; De Urraza, P J

    2010-09-01

    To isolate, characterize and select phages as potential biocontrol agents of enterohemorrhagic and Shiga toxin-producing Escherichia coli (EHEC and STEC) in cattle. Sixteen STEC and EHEC coliphages were isolated from bovine minced meat and stool samples and characterized with respect to their host range against STEC, EHEC and other Gram-negative pathogens; their morphology by electron microscopy; the presence of the stx1, stx2 and cI genes by means of PCR; RAPD and rep-PCR profiles; plaque formation; and acid resistance. Six isolates belonged to the Myoviridae and 10 to the Podoviridae families. The phages negative for stx and cI that formed large, well-defined plaques were all isolated using EHEC O157:H7 as host. Among them, only CA911 was a myophage and, together with CA933P, had the broadest host range for STEC and EHEC; the latter phage also infected Shigella and Pseudomonas. Isolates CA911, MFA933P and MFA45D differed in particle morphology and amplification patterns by RAPD and rep-PCR and showed the highest acidity tolerance. Myophage CA911 and podophages CA933P, MFA933P and MFA45D were chosen as the best candidates for biocontrol of STEC and EHEC in cattle. This work employs steps for a rational selection and characterization of bacteriophages as therapeutic agents. This report constitutes the first documentation of STEC and EHEC phages isolated in Argentina and proposes for the first time the use of rep-PCR as a complement of RAPD on DNA fingerprinting of phages. © 2010 The Authors. Journal compilation © 2010 The Society for Applied Microbiology.

  13. Serotypes, virulence genes, and intimin types of shiga toxin-producing Escherichia coli and enteropathogenic Escherichia coli isolated from mastitic milk relevant to human health in Egypt.

    Science.gov (United States)

    Osman, Kamelia M; Mustafa, Ashgan M; Aly, Magdy A K; AbdElhamed, Ghada S

    2012-04-01

    Some foodborne pathogens can cause mastitis, in which the organism is directly excreted into milk. Therefore, we undertook the steps to determine the prevalence and molecular characteristics of Shiga toxin-producing Escherichia coli (STEC) isolates from bovine mastitic milk in Egypt. Forty milk samples from dairy cattle showing mastitis were collected and examined for the presence of E. coli. Following enrichment and plating on selective agar, confirmation of the isolates was based on biochemical tests and the isolates were determined at the species level using cytochrome oxidase, triple sugar iron agar, urea, and indole tests as putatively E. coli. About 77.4% of the isolates belonged to four different O serogroups (O26, O86, O111, and O127). The multiplex polymerase chain reaction (PCR) found that the seven isolates revealed positive amplification of the Eagg gene from the extracted DNA of the E. coli isolates in an incidence of 100%. Also, the selected isolates were subjected to a simple PCR for the detection of 12 of the most important E. coli genes associated with virulence. Those genes detected were stx1, stx2, hylA, Flic(h7), stb, F41, K99, sta, F17, LT-I, LT-II, and eaeA. A total of seven E. coli isolates that were non-O157 isolates were investigated. Among the seven isolates, none was stx positive, and all seven lacked F41, K99, LT-I, LT-II, and Flic(h7). Of these seven isolates, three (42.85%) were enterohemorrhagic E. coli hlyA positive and two (28.57%) were eaeA positive. STEC isolates were not found in bovine mastitic milk in Egypt. Isolates from mastitic milk were potentially pathogenic for human in that they belonged to serogroups associated with diarrhea and hemolytic-uremic syndrome, and some of them were hylA, stb, sta, F17, and eaeA positive.

  14. Modeling uncertainty of estimated illnesses attributed to non-O157:H7 Shiga toxin-producing escherichia coli and its impact on illness cost.

    Science.gov (United States)

    Marks, Harry M; Tohamy, Soumaya M; Tsui, Flora

    2013-06-01

    Because of numerous reported foodborne illness cases due to non-O157:H7 Shiga toxin-producing Escherichia coli (STEC) bacteria in the United States and elsewhere, interest in requiring better control of these pathogens in the food supply has increased. Successfully putting forth regulations depends upon cost-benefit analyses. Policy decisions often depend upon an evaluation of the uncertainty of the estimates used in such an analysis. This article presents an approach for estimating the uncertainties of estimated expected cost per illness and total annual costs of non-O157 STEC-related illnesses due to uncertainties associated with (i) recent FoodNet data and (ii) methodology proposed by Scallan et al. in 2011. The FoodNet data categorize illnesses regarding hospitalization and death. We obtained the illness-category costs from the foodborne illness cost calculator of the U.S. Department of Agriculture, Economic Research Service. Our approach for estimating attendant uncertainties differs from that of Scallan et al. because we used a classical bootstrap procedure for estimating uncertainty of an estimated parameter value (e.g., mean value), reflecting the design of the FoodNet database, whereas the other approach results in an uncertainty distribution that includes an extraneous contribution due to the underlying variability of the distribution of illnesses among different sites. For data covering 2005 through 2010, we estimate that the average cost per illness was about $450, with a 98% credible interval of $230 to $1,000. This estimate and range are based on estimations of about one death and 100 hospitalizations per 34,000 illnesses. Our estimate of the total annual cost is about $51 million, with a 98% credible interval of $19 million to $122 million. The uncertainty distribution for total annual cost is approximated well by a lognormal distribution, with mean and standard deviations for the log-transformed costs of 10.765 and 0.390, respectively.

  15. Detection of non-O157 Shiga toxin-producing Escherichia coli in 375 grams of beef trim enrichments across multiple commercial PCR detection platforms.

    Science.gov (United States)

    Wheeler, Sarita Raengpradub; Heard, Preciaus; Dufour, Christophe; Thevenot-Sergentet, Delphine; Loukiadis, Estelle; Flowers, Russell S; McMahon, Wendy

    2015-01-01

    Although serotype O157:H7 remains the pathogenic Shiga toxin-producing Escherichia coli (STEC) of primary concern worldwide, some focus in the United States has shifted to six particular non-O157 STEC serogroups (O26, O45, O103, O111, O121, and O145). Some of these serogroups have also emerged as concerns elsewhere around the world, including Europe. The objective of this work was to compare commercial detection methods with the U.S. Department of Agriculture (USDA) reference method for detection of non-O157 STEC in 375 g of beef trim using a limit of detection study design. Overall, the commercial platforms performed well, showing similar levels of sensitivity for detection of presumptive positives for O45, O26, O103, and O121 (PCR screen results only). For O111, one method that utilizes an integrated immunomagnetic separation and PCR approach was more sensitive than a PCR-only screen approach. Additionally, one commercial method showed more presumptive and confirmed positives overall. Use of an immunomagnetic separation tool, such as antibody-coated beads, aided considerably with the confirmation procedures and is an important step when confirming suspect samples. A secondary goal of this study was to evaluate isolation and International Organization for Standardization confirmation protocols used in Europe compared with strategies provided by the USDA Microbiology Laboratory Guidebook (MLG). Generally, results from the USDA confirmation plates (modified Rainbow agar) were better than the European Union confirmation plates (MacConkey agar with or without rhamnose). In summary, detection of non-O157 STEC in 375 g of beef trim can be performed by any of the three methods on the market evaluated in the study.

  16. Molecular characterisation of human Shiga toxin-producingEscherichia coliO26 strains: results of an outbreak investigation, Romania, February to August 2016.

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    Usein, Codruţa-Romaniţa; Ciontea, Adriana Simona; Militaru, Cornelia Mãdãlina; Condei, Maria; Dinu, Sorin; Oprea, Mihaela; Cristea, Daniela; Michelacci, Valeria; Scavia, Gaia; Zota, Lavinia Cipriana; Zaharia, Alina; Morabito, Stefano

    2017-11-01

    IntroductionAt the beginning of 2016, an increase in paediatric haemolytic uremic syndrome (HUS) cases was observed in Romania. The microbiological investigations allowed isolation of Shiga toxin-producing Escherichia coli (STEC) O26 as the causative agent from most cases. Methods: An enhanced national surveillance of HUS and severe diarrhoea was established across the country following the identification of the first cases and was carried out until August 2016. A total of 15 strains were isolated from 10 HUS and five diarrhoea cases. Strains were characterised by virulence markers (i.e. stx type/subtype, eae , ehxA genes), phylogroup, genetic relatedness and clonality using PCR-based assays, PFGE and multilocus sequence typing (MLST). The first six strains were further characterised by whole genome sequencing (WGS). Results: Five PCR-defined genotypes were distinguished. All strains from HUS cases harboured stx2a and eae , with or without stx1a , while strains from diarrhoea cases carried exclusively stx1a and eae genes. PFGE resolved strains into multiple pulsotypes, compatible with a certain geographic segregation of the cases, and strains were assigned to phylogroup B1 and sequence type (ST) 21. WGS confirmed the results of conventional molecular methods, brought evidence of O26:H11 serotype, and complemented the virulence profiles. Discussion/conclusion: This first description of STEC O26 strains from cases in Romania showed that the isolates belonged to a diverse population. The virulence content of most strains highlighted a high risk for severe outcome in infected patients. Improving the national surveillance strategy for STEC infections in Romania needs to be further considered.

  17. Implementation of Whole Genome Sequencing (WGS) for Identification and Characterization of Shiga Toxin-Producing Escherichia coli (STEC) in the United States.

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    Lindsey, Rebecca L; Pouseele, Hannes; Chen, Jessica C; Strockbine, Nancy A; Carleton, Heather A

    2016-01-01

    Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen capable of causing severe disease in humans. Rapid and accurate identification and characterization techniques are essential during outbreak investigations. Current methods for characterization of STEC are expensive and time-consuming. With the advent of rapid and cheap whole genome sequencing (WGS) benchtop sequencers, the potential exists to replace traditional workflows with WGS. The aim of this study was to validate tools to do reference identification and characterization from WGS for STEC in a single workflow within an easy to use commercially available software platform. Publically available serotype, virulence, and antimicrobial resistance databases were downloaded from the Center for Genomic Epidemiology (CGE) (www.genomicepidemiology.org) and integrated into a genotyping plug-in with in silico PCR tools to confirm some of the virulence genes detected from WGS data. Additionally, down sampling experiments on the WGS sequence data were performed to determine a threshold for sequence coverage needed to accurately predict serotype and virulence genes using the established workflow. The serotype database was tested on a total of 228 genomes and correctly predicted from WGS for 96.1% of O serogroups and 96.5% of H serogroups identified by conventional testing techniques. A total of 59 genomes were evaluated to determine the threshold of coverage to detect the different WGS targets, 40 were evaluated for serotype and virulence gene detection and 19 for the stx gene subtypes. For serotype, 95% of the O and 100% of the H serogroups were detected at > 40x and ≥ 30x coverage, respectively. For virulence targets and stx gene subtypes, nearly all genes were detected at > 40x, though some targets were 100% detectable from genomes with coverage ≥20x. The resistance detection tool was 97% concordant with phenotypic testing results. With isolates sequenced to > 40x coverage, the different

  18. Shiga toxin-producing Escherichia coli (STEC) O22:H8 isolated from cattle reduces E. coli O157:H7 adherence in vitro and in vivo.

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    Martorelli, L; Albanese, A; Vilte, D; Cantet, R; Bentancor, A; Zolezzi, G; Chinen, I; Ibarra, C; Rivas, M; Mercado, E C; Cataldi, A

    2017-09-01

    Shiga toxin-producing Escherichia coli (STEC) are a group of bacteria responsible for food-associated diseases. Clinical features include a wide range of symptoms such as diarrhea, hemorrhagic colitis and the hemolytic uremic syndrome (HUS), a life-threatening condition. Our group has observed that animals naturally colonized with STEC strains of unknown serotype were not efficiently colonized with E. coli O157:H7 after experimental infection. In order to assess the basis of the interference, three STEC strains were isolated from STEC persistently-colonized healthy cattle from a dairy farm in Buenos Aires, Argentina. The three isolated strains are E. coli O22:H8 and carry the stx1 and stx2d genes. The activatable activity of Stx2d was demonstrated in vitro. The three strains carry the adhesins iha, ehaA and lpf O113 . E. coli O22:H8 formed stronger biofilms in abiotic surface than E. coli O157:H7 (eae+, stx2+) and displayed a more adherent phenotype in vitro towards HeLa cells. Furthermore, when both serotypes were cultured together O22:H8 could reduce O157:H7 adherence in vitro. When calves were intragastrically pre-challenged with 10 8 CFU of a mixture of the three STEC strains and two days later challenged with the same dose of the strain E. coli O157:H7 438/99, the shedding of the pathogen was significantly reduced. These results suggest that E. coli O22:H8, a serotype rarely associated with human illness, might compete with O157:H7 at the bovine recto-anal junction, making non-O157 carrying-calves less susceptible to O157:H7 colonization and shedding of the bacteria to the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Prevalence and behavior of multidrug-resistant shiga toxin-producing Escherichia coli, enteropathogenic E. coli and enterotoxigenic E. coli on coriander.

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    Gómez-Aldapa, Carlos A; Segovia-Cruz, Jesús A; Cerna-Cortes, Jorge F; Rangel-Vargas, Esmeralda; Salas-Rangel, Laura P; Gutiérrez-Alcántara, Eduardo J; Castro-Rosas, Javier

    2016-10-01

    The prevalence and behavior of multidrug-resistant diarrheagenic Escherichia coli pathotypes on coriander was determined. One hundred coriander samples were collected from markets. Generic E. coli were determined using the most probable number procedure. Diarrheagenic E. coli pathotypes (DEPs) were identified using two multiplex polymerase chain reaction procedures. Susceptibility to sixteen antibiotics was tested for the isolated DEPs strains by standard test. The behavior of multidrug-resistant DEPs isolated from coriander was determined on coriander leaves and chopped coriander at 25°± 2 °C and 3°± 2 °C. Generic E. coli and DEPs were identified, respectively, in 43 and 7% of samples. Nine DEPs strains were isolated from positive coriander samples. The identified DEPs included Shiga toxin-producing E. coli (STEC, 4%) enterotoxigenic E. coli (ETEC, 2%) and enteropathogenic E. coli (EPEC, 1%). All isolated DEPs strains exhibited multi-resistance to antibiotics. On inoculated coriander leaves stored at 25°± 2 °C or 3°± 2 °C, no growth was observed for multidrug-resistant DEPs strains. However, multidrug-resistant DEPs strains grew in chopped coriander: after 24 h at 25° ± 2 °C, DEPs strains had grown to approximately 3 log CFU/g. However, at 3°± 2 °C the bacterial growth was inhibited. To the best of our knowledge, this is the first report of the presence and behavior of multidrug-resistant STEC, ETEC and EPEC on coriander and chopped coriander. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Structure and function relationship of the autotransport and proteolytic activity of EspP from Shiga toxin-producing Escherichia coli.

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    Jens Brockmeyer

    Full Text Available BACKGROUND: The serine protease autotransporter EspP is a proposed virulence factor of Shiga toxin-producing Escherichia coli (STEC. We recently distinguished four EspP subtypes (EspPalpha, EspPbeta, EspPgamma, and EspPdelta, which display large differences in transport and proteolytic activities and differ widely concerning their distribution within the STEC population. The mechanisms underlying these functional variations in EspP subtypes are, however, unknown. METHODOLOGY/PRINCIPAL FINDINGS: The structural basis of proteolytic and autotransport activity was investigated using transposon-based linker scanning mutagenesis, site-directed mutagenesis and structure-function analysis derived from homology modelling of the EspP passenger domain. Transposon mutagenesis of the passenger domain inactivated autotransport when pentapeptide linker insertions occurred in regions essential for overall correct folding or in a loop protruding from the beta-helical core. Loss of proteolytic function was limited to mutations in Domain 1 in the N-terminal third of the EspP passenger. Site-directed mutagenesis demonstrated that His(127, Asp(156 and Ser(263 in Domain 1 form the catalytic triad of EspP. CONCLUSIONS/SIGNIFICANCE: Our data indicate that in EspP i the correct formation of the tertiary structure of the passenger domain is essential for efficient autotransport, and ii an elastase-like serine protease domain in the N-terminal Domain 1 is responsible for the proteolytic phenotype. Lack of stabilizing interactions of Domain 1 with the core structure of the passenger domain ablates proteolytic activity in subtypes EspPbeta and EspPdelta.

  1. Circulating microRNAs in patients with Shiga-Toxin-producing E. coli O104:H4 induced hemolytic uremic syndrome.

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    Johan M Lorenzen

    Full Text Available BACKGROUND: In early May 2011, an outbreak of hemorrhagic colitis associated with hemolytic-uremic syndrome (HUS first developed in Northern Germany and spread to 15 other countries in Europe. The outbreak-strain O104:H4, which combined virulence factors of typical enteroaggregative and Shiga-Toxin-producing E. coli was associated with an unusual high rate of hemolytic uremic syndrome. Also an unexpected high rate of coma and seizures leading to mechanical ventilation and ICU treatment was observed. MicroRNAs are small ribonucleotides orchestrating gene expression. We tested whether circulating microRNAs in serum of HUS patients during the 2011 epidemics are altered in this patient cohort and related to clinical manifestations. METHODOLOGY/PRINCIPAL FINDINGS: We profiled microRNAs using RNA isolated from serum of patients and healthy age-matched controls. The results were validated in 38 patients at baseline, 29 patients during follow-up and 21 age-matched healthy controls by miRNA-specific quantitative RT-PCR. Circulating levels of miR-24, miR-126 were increased in HUS patients versus controls. There was no association between these microRNAs and renal function or the need for renal replacement therapy. In contrast, levels of miR-126 were associated with neurological symptoms at baseline and during follow-up. In addition, miR-126 (on admission and miR-24 (on admission and during follow-up were associated with platelet count. CONCLUSIONS/SIGNIFICANCE: Circulating microRNAs are strongly altered in this patient cohort and associated with neurological symptoms as well as platelet count.

  2. Prevalence of Shiga toxin-producing Escherichia coli, Salmonella spp. and Campylobacter spp. in large game animals intended for consumption: relationship with management practices and livestock influence.

    Science.gov (United States)

    Díaz-Sánchez, S; Sánchez, S; Herrera-León, S; Porrero, C; Blanco, J; Dahbi, G; Blanco, J E; Mora, A; Mateo, R; Hanning, I; Vidal, D

    2013-05-03

    Although wild ruminants have been identified as reservoirs of Shiga-toxin producing Escherichia coli (STEC), little information is available concerning the role of Salmonella spp. and Campylobacter spp. in large game species. We evaluated the presence of these pathogens in faeces (N=574) and carcasses (N=585) sampled from red deer (N=295), wild boar (N=333) and other ungulates (fallow deer, mouflon) (N=9). Animal sampling was done in situ from 33 hunting estates during two hunting seasons. Salmonella spp. and Campylobacter spp. strains associated with human campylobacteriosis were infrequently detected indicating that both pathogens had a limited zoonotic risk in our study area. The overall STEC prevalence in animals was 21% (134/637), being significantly higher in faeces from red deer (90 out of 264). A total of 58 isolates were serotyped. Serotypes O146:H- and O27:H30 were the most frequent in red deer and the majority of isolates from red deer and wild boar were from serotypes previously found in STEC strains associated with human infection, including the serotype O157:H7. The STEC prevalence in red deer faeces was significantly higher with the presence of livestock (p<0, 01) where high densities of red deer (p<0.001) were present. To the best of our knowledge, this is the first study reporting the occurrence of Salmonella spp. and STEC in carcasses of large game animals. Furthermore, this study confirmed by pulsed-field gel electrophoresis (PFGE) that cross contamination of STEC during carcass dressing occurred, implying the likelihood of these pathogens entering into the food chain. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Antimicrobial resistance profiles of Shiga toxin-producing Escherichia coli O157 and Non-O157 recovered from domestic farm animals in rural communities in Northwestern Mexico

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    Bianca A. Amézquita-López

    2016-01-01

    Full Text Available Abstract Background Antimicrobial resistance in Shiga toxin-producing Escherichia coli (STEC O157 and non-O157 is a matter of increasing concern. The aim of the present study was to investigate the antimicrobial resistance profiles of STEC O157 and non-O157 recovered from feces of domestic farm animals in the agricultural Culiacan Valley in Northwestern Mexico. Findings All of the examined STEC strains showed susceptibility to five antimicrobials, ceftazidime, ceftriaxone, ciprofloxacin, nalidixic acid, and trimethoprim-sulfamethoxazole. However, resistance to the four antimicrobials, ampicillin, cephalothin, chloramphenicol, and kanamycin was commonly observed. Interestingly, non-susceptibility to cephalothin was predominant among the examined STEC strains, corresponding to 85 % (22/26 of the O157:H7 from cattle, sheep and chicken and 73 % (24/33 of the non-O157 strains from cattle and sheep. Statistical analyses revealed that resistance to ampicillin was significantly correlated to 38 % (10/26 of STEC O157:H7 strains from multiple animal sources. Another significant correlation was found between serotype, source, and antimicrobial resistance; all of the O20:H4 strains, recovered from sheep, were highly resistant to tetracycline. Multidrug resistance profiles were identified in 42 % (22/53 of the non-susceptible STEC strains with clinically-relevant serotypes O8:H9, O75:H8, O146:H21, and O157:H7. Conclusions STEC O157 and non-O157 strains, recovered from domestic farm animals in the Culiacan Valley, exhibited resistance to classes of antimicrobials commonly used in Mexico, such as aminoglycosides, tetracyclines, cephalosporins and penicillin but were susceptible to fluoroquinolones, quinolones, and sulfonamides. These findings provide fundamental information that would aid in the surveillance of antimicrobial resistance in an important agricultural region in Northwestern Mexico.

  4. The evolutionary divergence of Shiga toxin-producing Escherichia coli is reflected in clustered regularly interspaced short palindromic repeat (CRISPR) spacer composition.

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    Yin, Shuang; Jensen, Mark A; Bai, Jiawei; Debroy, Chitrita; Barrangou, Rodolphe; Dudley, Edward G

    2013-09-01

    The Shiga toxin-producing Escherichia coli (STEC) strains, including those of O157:H7 and the "big six" serogroups (i.e., serogroups O26, O45, O103, O111, O121, and O145), are a group of pathogens designated food adulterants in the United States. The relatively conserved nature of clustered regularly interspaced short palindromic repeats (CRISPRs) in phylogenetically related E. coli strains makes them potential subtyping markers for STEC detection, and a quantitative PCR (qPCR)-based assay was previously developed for O26:H11, O45:H2, O103:H2, O111:H8, O121:H19, O145:H28, and O157:H7 isolates. To better evaluate the sensitivity and specificity of this qPCR method, the CRISPR loci of 252 O157 and big-six STEC isolates were sequenced and analyzed along with 563 CRISPR1 and 624 CRISPR2 sequences available in GenBank. General conservation of spacer content and order was observed within each O157 and big-six serogroup, validating the qPCR method. Meanwhile, it was found that spacer deletion, the presence of an insertion sequence, and distinct alleles within a serogroup are sources of false-negative reactions. Conservation of CRISPR arrays among isolates expressing the same flagellar antigen, specifically, H7, H2, and H11, suggested that these isolates share an ancestor and provided an explanation for the false positives previously observed in the qPCR results. An analysis of spacer distribution across E. coli strains provided limited evidence for temporal spacer acquisition. Conversely, comparison of CRISPR sequences between strains along the stepwise evolution of O157:H7 from its O55:H7 ancestor revealed that, over this ∼7,000-year span, spacer deletion was the primary force generating CRISPR diversity.

  5. Comparative Genomics of Recent Shiga Toxin-Producing Escherichia coli O104:H4: Short-Term Evolution of an Emerging Pathogen

    Science.gov (United States)

    Grad, Yonatan H.; Godfrey, Paul; Cerquiera, Gustavo C.; Mariani-Kurkdjian, Patricia; Gouali, Malika; Bingen, Edouard; Shea, Terrence P.; Haas, Brian J.; Griggs, Allison; Young, Sarah; Zeng, Qiandong; Lipsitch, Marc; Waldor, Matthew K.; Weill, François-Xavier; Wortman, Jennifer R.; Hanage, William P.

    2013-01-01

    ABSTRACT The large outbreak of diarrhea and hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli O104:H4 in Europe from May to July 2011 highlighted the potential of a rarely identified E. coli serogroup to cause severe disease. Prior to the outbreak, there were very few reports of disease caused by this pathogen and thus little known of its diversity and evolution. The identification of cases of HUS caused by E. coli O104:H4 in France and Turkey after the outbreak and with no clear epidemiological links raises questions about whether these sporadic cases are derived from the outbreak. Here, we report genome sequences of five independent isolates from these cases and results of a comparative analysis with historical and 2011 outbreak isolates. These analyses revealed that the five isolates are not derived from the outbreak strain; however, they are more closely related to the outbreak strain and each other than to isolates identified prior to the 2011 outbreak. Over the short time scale represented by these closely related organisms, the majority of genome variation is found within their mobile genetic elements: none of the nine O104:H4 isolates compared here contain the same set of plasmids, and their prophages and genomic islands also differ. Moreover, the presence of closely related HUS-associated E. coli O104:H4 isolates supports the contention that fully virulent O104:H4 isolates are widespread and emphasizes the possibility of future food-borne E. coli O104:H4 outbreaks. PMID:23341549

  6. Detection and Characterization of Shiga Toxin Producing Escherichia coli, Salmonella spp., and Yersinia Strains from Human, Animal, and Food Samples in San Luis, Argentina

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    Gabriela Isabel Favier

    2014-01-01

    Full Text Available Shiga toxin producing Escherichia coli (STEC, Salmonella spp., and Yersinia species was investigated in humans, animals, and foods in San Luis, Argentina. A total of 453 samples were analyzed by culture and PCR. The antimicrobial susceptibility of all the strains was studied, the genomic relationships among isolates of the same species were determined by PFGE, and the potencial virulence of Y. enterocolitica strains was analyzed. Yersinia species showed higher prevalence (9/453, 2.0%, 95% CI, 0.7–3.3% than STEC (4/453, 0.9%, 95% CI, 0–1.8% and Salmonella spp. (3/453, 0.7%, 95% CI, 0–1.5%. Y. enterocolitica and Y. intermedia were isolated from chicken carcasses (6/80, 7.5%, 95% CI, 1.5–13.5% and porcine skin and bones (3/10, 30%, 95% CI, 0–65%. One STEC strain was recovered from human feces (1/70, 1.4%, 95% CI, 0–4.2% and STEC stx1/stx2 genes were detected in bovine stools (3/129, 2.3%, 95% CI, 0–5.0%. S. Typhimurium was isolated from human feces (1/70, 1.4%, 95% CI, 0–4.2% while one S. Newport and two S. Gaminara strains were recovered from one wild boar (1/3, 33%, 95% CI, 0–99%. The knowledge of prevalence and characteristics of these enteropathogens in our region would allow public health services to take adequate preventive measures.

  7. Distribution Pattern of EcoR Phylogenetic Groups Among Shiga Toxin-Producing and Enteropathogenic Escherichia coli Isolated From Healthy Goats

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    Maziar Jajarmi

    2015-08-01

    Full Text Available Background: Escherichia coli can be categorized into four major phylogenetic groups (A, B1, B2, and D based on presence or absence of three markers including two genes (chuA and yjaA and an anonymous DNA fragment designated TSPE4.C2. Also, these groups are divided into seven phylogenetic subgroups A0, A1, B1, B22, B23, D1, and D2. Objectives: This study aimed to determine the distribution pattern of phylogenetic groups in Shiga Toxin-Producing Escherichia coli (STEC and Enteropathogenic Escherichia coli (EPEC isolated from asymptomatic goats in Kerman city, Iran. Materials and Methods: Two hundred and fifty fecal samples were obtained from healthy goats. All isolates were subjected to detection of phylogenetic markers chuA, yjaA and DNA fragment TspE4.C2 and virulence genes stx1, stx2 and eae. Results: In summary, among all isolates phylo-group B1 was the most prevalent (57.6% and other phylo-groups were A1 (20.4%, A0 (18.4%, D1 (2.8%, and B22 (0.8%. There was no isolate in B23 and D2 subgroups. Fifty samples (20% possessed at least one of the tested virulencegenes : stx1 (12%, stx1/stx2 (4%, eae (2.8%, stx1/eae (0.8%, and stx2 (0.4%. Thus, 41 (16.4% STEC, 7 (2.8% EPEC, and 2 (0.8% Enterohemorrhagic Escherichia coli (EHEC strains were isolated and allocated into four phylogenetic subgroups A0 (16%, A1 (12%, B1 (68%, and D1 (4%. Conclusions: Based on 250 fecal samples obtained from goats in industrial slaughterhouse of Kerman City, goats may be a potential reservoir of STEC in Kerman and B1 followed by A are the most prevalent phylogenetic groups among STEC and non-STEC isolates in this study.

  8. Genetic characterization of Shiga toxin-producing Escherichia coli (STEC) and atypical enteropathogenic Escherichia coli (EPEC) isolates from goat's milk and goat farm environment.

    Science.gov (United States)

    Álvarez-Suárez, María-Elena; Otero, Andrés; García-López, María-Luisa; Dahbi, Ghizlane; Blanco, Miguel; Mora, Azucena; Blanco, Jorge; Santos, Jesús A

    2016-11-07

    The aim of this study was to characterize a collection of 44 Shiga toxin-producing (STEC) and enteropathogenic Escherichia coli (EPEC) isolated from goat milk and goat farm environment. Of the 19 STEC isolates, five (26.3%) carried the stx1 gene, four (21.1%) the stx2 gene and 10 (52.6%) presented both stx genes. Six (31.6%) STEC strains were eae-positive and belonged to serotypes related to severe human disease (O157:H7 and O5:HNM). Another seven STEC strains were of serotype O146:H21 and three of serotype O166:H28, also linked to human disease. The STEC strains isolated from goat milk were of serotypes potentially pathogenic for humans. All the 25 EPEC isolates were considered atypical (aEPEC) and one aEPEC strain was of serotype O26:H11, a serotype frequently isolated in children with diarrhea. Multilocus sequence typing (MLST) was carried out with seven housekeeping genes and 23 sequence types (ST) were detected, 14 of them newly described. Twelve STs grouped STEC isolates and 11 STs grouped EPEC isolates. Genetic typing by pulsed field gel electrophoresis (PFGE) resulted in 38 patterns which grouped in 10 clusters. Well-defined groups were also observed for strains of pathogenic serotypes. In conclusion, strains of STEC and aEPEC belonging to serotypes related to severe human disease have been detected in goat milk and the goat farm environment. Ruminants are an important reservoir of STEC strains and the role of these animals as carriers of other pathogenic types of E. coli seems to be an emerging concern. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Genetic Relatedness Among Shiga Toxin-Producing Escherichia coli Isolated Along the Animal Food Supply Chain and in Gastroenteritis Cases in Qatar Using Multilocus Sequence Typing.

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    Palanisamy, Srikanth; Chang, YuChen; Scaria, Joy; Penha Filho, Rafael Antonio Casarin; Peters, Kenlyn E; Doiphode, Sanjay H; Sultan, Ali; Mohammed, Hussni O

    2017-06-01

    Pathogenic Escherichia coli has been listed among the most important bacteria associated with foodborne illnesses around the world. We investigated the genetic relatedness among Shiga toxin-producing E. coli (STEC) isolated along the animal food supply chain and from humans diagnosed with gastroenteritis in Qatar. Samples were collected from different sources along the food supply chain and from patients admitted to the hospital with complaints of gastroenteritis. All samples were screened for the presence of E. coli O157:H7 and non-O157 STEC using a combination of bacterial enrichment and molecular detection techniques. A proportional sampling approach was used to select positive samples from each source for further multilocus sequence typing (MLST) analysis. Seven housekeeping genes described for STEC were amplified by polymerase chain reaction, sequenced, and analyzed by MLST. Isolates were characterized by allele composition, sequence type (ST) and assessed for epidemiologic relationship within and among different sources. Nei's genetic distance was calculated at the allele level between sample pools in each site downstream. E. coli O157:H7 occurred at a higher rate in slaughterhouse and retail samples than at the farm or in humans in our sampling. The ST171, an ST common to enterotoxigenic E. coli and atypical enteropathogenic E. coli, was the most common ST (15%) in the food supply chain. None of the genetic distances among the different sources was statistically significant. Enterohemorrhagic E. coli pathogenic strains are present along the supply chain at different levels and with varying relatedness. Clinical isolates were the most diverse, as expected, considering the polyclonal diversity in the human microbiota. The high occurrence of these food adulterants among the farm products suggests that implementation of sanitary measures at that level might reduce the risk of human exposure.

  10. Shiga-toxin producing 0157:H7 and non-0157:H7 Escherichia coli cells within refrigerated, frozen, or frozen then thawed ground beef patties cooked on commercial open-flame gas or clam-shell electric grills

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    We evaluated the possible effect of both fat and grill type on the fate of serotype O157:H7 strains of Escherichia coli (ECOH) and non-O157:H7 Shiga toxin producing strains of E. coli (STEC) in cooked ground beef patties. Both high fat and low fat ground beef (percent lean:fat = ca. 70:30 and 93:7, ...

  11. Distribution of Heat Stabilizers in Plasticized PVC-Based Biomedical Devices: Temperature and Time Effects

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    Lidia Maria Bodecchi

    2011-01-01

    Full Text Available Thermoplastic polymers can be viewed as a dynamic framework in which additives allocation is strongly dependent on the system' chemistry. Considering the complexity of the distribution phenomena that may occur in plastics obtained by blending polymeric resins with different additives, this work constitutes an attempt to the description of the behavior of PVC heat stabilizers (calcium and zinc carboxylates, as regard temperature and time. Thanks to the Fourier Transform Infrared Spectroscopy, it is possible to observe a first decreasing trend of the additives related IR-bands as a function of the increasing temperature and the higher the temperature the faster the decrease of the heat stabilizers intensities bands is, with respect to time. Additives distribution in not sterilized, sterilized, aged not sterilized and aged sterilized materials have been investigated to determine their behavior with respect to temperature, from 30 to 120°C, and time. A simulated supplementary aging process equivalent to 9 months aging was carried out on aged not sterilized and aged sterilized materials to gain more data on the transport/reaction phenomena these additives in the plastic material. Experimental evidences allow hypothesizing that reaction and redistribution phenomena probably concur to determine the additives allocation in PVC as a function of temperature and time.

  12. Implications of screening and childcare exclusion policies for children with Shiga-toxin producing Escherichia coli infections: lessons learned from an outbreak in a daycare centre, Norway, 2012.

    Science.gov (United States)

    MacDonald, Emily; Dalane, Per Kjetil; Aavitsland, Preben; Brandal, Lin Thorstensen; Wester, Astrid Louise; Vold, Line

    2014-12-18

    In Norway, it is recommended that children with Shiga-Toxin producing Escherichia coli (STEC) infections are excluded from daycare centers until up to five consecutive negative stool cultures are obtained. Children with gastrointestinal illness of unknown etiology are asked to remain home for 48 hours after symptoms subside. On 16 October 2012, two cases of STEC infection were reported from a daycare center, where other children were also symptomatic. Local health authorities temporarily closed the daycare center and all children and staff were screened for pathogenic E. coli. We present the results of the outbreak investigation in order to discuss the implications of screening and the exclusion policies for children attending daycare in Norway. Stool specimens for all children (n = 91) and employees at the daycare center (n = 40) were tested for pathogenic E. coli. Information on demographics, symptoms and potential exposures was collected from parents through trawling interviews and a web-based questionnaire. Cases were monitored to determine the duration of shedding and the resulting exclusion period from daycare. We identified five children with stx1- and eae-positive STEC O103:H2 infections, and one staff member and one child with STEC O91:H- infections. Three additional children who tested positive for stx1 and eae genes were considered probable STEC cases. Three cases were asymptomatic. Median length of time of exclusion from daycare for STEC cases was 53 days (range 9 days-108 days). Survey responses for 75 children revealed mild gastrointestinal symptoms among both children with STEC infections and children with negative microbiological results. There was no evidence of common exposures; person-to-person transmission was likely. The results of screening indicate that E. coli infections can spread in daycare centres, reflected in the proportion of children with STEC and EPEC infections. While screening can identify asymptomatic cases, the

  13. Isolation and characterization of non-O157 Shiga toxin-producing Escherichia coli from beef carcasses, cuts and trimmings of abattoirs in Argentina

    Science.gov (United States)

    Brusa, Victoria; Restovich, Viviana; Galli, Lucía; Teitelbaum, David; Signorini, Marcelo; Brasesco, Hebe; Londero, Alejandra; García, Diego; Padola, Nora Lía; Superno, Valeria; Sanz, Marcelo; Petroli, Sandra; Costa, Magdalena; Bruzzone, Mariana; Sucari, Adriana; Ferreghini, Marcela; Linares, Luciano; Suberbie, Germán; Rodríguez, Ricardo

    2017-01-01

    Several foods contaminated with Shiga toxin-producing Escherichia coli (STEC) are associated with human diseases. Some countries have established microbiological criteria for non-O157 STEC, thus, the absence of serogroups O26, O45, O103, O104, O111, O121, and O145 in sprouts from the European Union or ground beef and beef trimmings from the United States is mandatory. While in Argentina screening for O26, O103, O111, O145 and O121 in ground beef, ready-to-eat food, sausages and vegetables is mandatory, other countries have zero-tolerance for all STEC in chilled beef. The aim of this study was to provide data on the prevalence of non-O157 STEC isolated from beef processed in eight Argentinean cattle slaughterhouses producing beef for export and local markets, and to know the non-O157 STEC profiles through strain characterization and genotypic analysis. Samples (n = 15,965) from 3,205 beef carcasses, 9,570 cuts and 3,190 trimmings collected between March and September 2014 were processed in pools of five samples each. Pools of samples (n = 3,193) from 641 carcasses, 1,914 cuts and 638 trimming were analyzed for non-O157 STEC isolation according to ISO/CEN 13136:2012. Of these, 37 pools of carcasses (5.8%), 111 pools of cuts (5.8%) and 45 pools of trimmings (7.0%) were positive for non-O157 STEC. STEC strains (n = 200) were isolated from 193 pools of samples. The most prevalent serotypes were O174:H21, O185:H7, O8:H19, O178:H19 and O130:H11, and the most prevalent genotypes were stx2c(vh-b) and stx2a/saa/ehxA. O103:H21 strain was eae-positive and one O178:H19 strain was aggR/aaiC-positive. The prevalence of non-O157 STEC in beef carcasses reported here was low. None of the non-O157 STEC strains isolated corresponded to the non-O157 STEC serotypes and virulence profiles isolated from human cases in Argentina in the same study period. The application of microbiological criteria for each foodstuff should be determined by risk analysis in order to have a stringent

  14. Isolation and characterization of non-O157 Shiga toxin-producing Escherichia coli from beef carcasses, cuts and trimmings of abattoirs in Argentina.

    Science.gov (United States)

    Brusa, Victoria; Restovich, Viviana; Galli, Lucía; Teitelbaum, David; Signorini, Marcelo; Brasesco, Hebe; Londero, Alejandra; García, Diego; Padola, Nora Lía; Superno, Valeria; Sanz, Marcelo; Petroli, Sandra; Costa, Magdalena; Bruzzone, Mariana; Sucari, Adriana; Ferreghini, Marcela; Linares, Luciano; Suberbie, Germán; Rodríguez, Ricardo; Leotta, Gerardo A

    2017-01-01

    Several foods contaminated with Shiga toxin-producing Escherichia coli (STEC) are associated with human diseases. Some countries have established microbiological criteria for non-O157 STEC, thus, the absence of serogroups O26, O45, O103, O104, O111, O121, and O145 in sprouts from the European Union or ground beef and beef trimmings from the United States is mandatory. While in Argentina screening for O26, O103, O111, O145 and O121 in ground beef, ready-to-eat food, sausages and vegetables is mandatory, other countries have zero-tolerance for all STEC in chilled beef. The aim of this study was to provide data on the prevalence of non-O157 STEC isolated from beef processed in eight Argentinean cattle slaughterhouses producing beef for export and local markets, and to know the non-O157 STEC profiles through strain characterization and genotypic analysis. Samples (n = 15,965) from 3,205 beef carcasses, 9,570 cuts and 3,190 trimmings collected between March and September 2014 were processed in pools of five samples each. Pools of samples (n = 3,193) from 641 carcasses, 1,914 cuts and 638 trimming were analyzed for non-O157 STEC isolation according to ISO/CEN 13136:2012. Of these, 37 pools of carcasses (5.8%), 111 pools of cuts (5.8%) and 45 pools of trimmings (7.0%) were positive for non-O157 STEC. STEC strains (n = 200) were isolated from 193 pools of samples. The most prevalent serotypes were O174:H21, O185:H7, O8:H19, O178:H19 and O130:H11, and the most prevalent genotypes were stx2c(vh-b) and stx2a/saa/ehxA. O103:H21 strain was eae-positive and one O178:H19 strain was aggR/aaiC-positive. The prevalence of non-O157 STEC in beef carcasses reported here was low. None of the non-O157 STEC strains isolated corresponded to the non-O157 STEC serotypes and virulence profiles isolated from human cases in Argentina in the same study period. The application of microbiological criteria for each foodstuff should be determined by risk analysis in order to have a stringent

  15. Multiplex real-time PCR assay for detection of Escherichia coli O157:H7 and screening for non-O157 Shiga toxin-producing E. coli.

    Science.gov (United States)

    Li, Baoguang; Liu, Huanli; Wang, Weimin

    2017-11-09

    Shiga toxin-producing Escherichia coli (STEC), including E. coli O157:H7, are responsible for numerous foodborne outbreaks annually worldwide. E. coli O157:H7, as well as pathogenic non-O157:H7 STECs, can cause life-threating complications, such as bloody diarrhea (hemolytic colitis) and hemolytic-uremic syndrome (HUS). Previously, we developed a real-time PCR assay to detect E. coli O157:H7 in foods by targeting a unique putative fimbriae protein Z3276. To extend the detection spectrum of the assay, we report a multiplex real-time PCR assay to specifically detect E. coli O157:H7 and screen for non-O157 STEC by targeting Z3276 and Shiga toxin genes (stx1 and stx2). Also, an internal amplification control (IAC) was incorporated into the assay to monitor the amplification efficiency. The multiplex real-time PCR assay was developed using the Life Technology ABI 7500 System platform and the standard chemistry. The optimal amplification mixture of the assay contains 12.5 μl of 2 × Universal Master Mix (Life Technology), 200 nM forward and reverse primers, appropriate concentrations of four probes [(Z3276 (80 nM), stx1 (80 nM), stx2 (20 nM), and IAC (40 nM)], 2 μl of template DNA, and water (to make up to 25 μl in total volume). The amplification conditions of the assay were set as follows: activation of TaqMan at 95 °C for 10 min, then 40 cycles of denaturation at 95 °C for 10 s and annealing/extension at 60 °C for 60 s. The multiplex assay was optimized for amplification conditions. The limit of detection (LOD) for the multiplex assay was determined to be 200 fg of bacterial DNA, which is equivalent to 40 CFU per reaction which is similar to the LOD generated in single targeted PCRs. Inclusivity and exclusivity determinants were performed with 196 bacterial strains. All E. coli O157:H7 (n = 135) were detected as positive and all STEC strains (n = 33) were positive for stx1, or stx2, or stx1 and stx2 (Table 1). No cross reactivity was detected with Salmonella

  16. Longitudinal study of two Irish dairy herds: Low numbers of of Shiga toxin-producing Escherichia coli O157 and O26 super-shedders identified

    Directory of Open Access Journals (Sweden)

    Brenda Patricia Murphy

    2016-11-01

    Full Text Available A 12-month longitudinal study was undertaken on two dairy herds to ascertain the Shiga-toxin producing Escherichia coli (STEC O157 and O26 shedding status of the animals and its impact (if any on raw milk. Cattle are a recognised reservoir for these organisms with associated public health and environmental implications. Animals shedding E. coli O157 at >10,000 CFU/g of faeces have been deemed super-shedders. There is a gap in the knowledge regarding super-shedding of other STEC serogroups. A cohort of 40 lactating cows from herds previously identified as positive for VTEC in a national surveillance project were sampled every second month between August, 2013 and July, 2014. Metadata on any potential super-shedders was documented including e.g. age of the animal, number of lactations and days in lactation, nutritional condition, somatic cell count and content of protein in milk to assess if any were associated with risk factors for super-shedding. Recto-anal mucosal swabs, raw milk, milk filters and water samples were procured for each herd. The swabs were examined for E. coli O157 and O26 using a quantitative real time PCR method. Counts (CFU swab-1 were obtained from a standard calibration curve that related real-time PCR cycle threshold (Ct values against the initial concentration of O157 or O26 in the samples. Results from Farm A: 305 animals were analysed; 15 E. coli O157 (5% were recovered, 13 were denoted STEC encoding either stx1 and/or stx2 virulence genes and 5 (2% STEC O26 were recovered. One super-shedder was identified shedding STEC O26 (stx1&2. Farm B: 224 animals were analysed; eight E. coli O157 (3.5% were recovered (seven were STEC and 9 (4% STEC O26 were recovered. Three super-shedders were identified, one was shedding STEC O157 (stx2 and two STEC O26 (stx2. Three encoded the adhering and effacement gene (eae and one isolate additionally encoded the haemolysin gene (hlyA. The results of this study show, low numbers of super

  17. Genotypic analyses of shiga toxin-producing Escherichia coli O157 and non-O157 recovered from feces of domestic animals on rural farms in Mexico.

    Directory of Open Access Journals (Sweden)

    Bianca A Amézquita-López

    Full Text Available Shiga toxin-producing Escherichia coli (STEC are zoonotic enteric pathogens associated with human gastroenteritis worldwide. Cattle and small ruminants are important animal reservoirs of STEC. The present study investigated animal reservoirs for STEC in small rural farms in the Culiacan Valley, an important agricultural region located in Northwest Mexico. A total of 240 fecal samples from domestic animals were collected from five sampling sites in the Culiacan Valley and were subjected to an enrichment protocol followed by either direct plating or immunomagnetic separation before plating on selective media. Serotype O157:H7 isolates with the virulence genes stx2, eae, and ehxA were identified in 40% (26/65 of the recovered isolates from cattle, sheep and chicken feces. Pulse-field gel electrophoresis (PFGE analysis grouped most O157:H7 isolates into two clusters with 98.6% homology. The use of multiple-locus variable-number tandem repeat analysis (MLVA differentiated isolates that were indistinguishable by PFGE. Analysis of the allelic diversity of MLVA loci suggested that the O157:H7 isolates from this region were highly related. In contrast to O157:H7 isolates, a greater genotypic diversity was observed in the non-O157 isolates, resulting in 23 PFGE types and 14 MLVA types. The relevant non-O157 serotypes O8:H19, O75:H8, O111:H8 and O146:H21 represented 35.4% (23/65 of the recovered isolates. In particular, 18.5% (12/65 of all the isolates were serotype O75:H8, which was the most variable serotype by both PFGE and MLVA. The non-O157 isolates were predominantly recovered from sheep and were identified to harbor either one or two stx genes. Most non-O157 isolates were ehxA-positive (86.5%, 32/37 but only 10.8% (4/37 harbored eae. These findings indicate that zoonotic STEC with genotypes associated with human illness are present in animals on small farms within rural communities in the Culiacan Valley and emphasize the need for the development of

  18. Genotypic Analyses of Shiga Toxin-Producing Escherichia coli O157 and Non-O157 Recovered from Feces of Domestic Animals on Rural Farms in Mexico

    Science.gov (United States)

    Amézquita-López, Bianca A.; Quiñones, Beatriz; Cooley, Michael B.; León-Félix, Josefina; Castro-del Campo, Nohelia; Mandrell, Robert E.; Jiménez, Maribel; Chaidez, Cristóbal

    2012-01-01

    Shiga toxin-producing Escherichia coli (STEC) are zoonotic enteric pathogens associated with human gastroenteritis worldwide. Cattle and small ruminants are important animal reservoirs of STEC. The present study investigated animal reservoirs for STEC in small rural farms in the Culiacan Valley, an important agricultural region located in Northwest Mexico. A total of 240 fecal samples from domestic animals were collected from five sampling sites in the Culiacan Valley and were subjected to an enrichment protocol followed by either direct plating or immunomagnetic separation before plating on selective media. Serotype O157:H7 isolates with the virulence genes stx2, eae, and ehxA were identified in 40% (26/65) of the recovered isolates from cattle, sheep and chicken feces. Pulse-field gel electrophoresis (PFGE) analysis grouped most O157:H7 isolates into two clusters with 98.6% homology. The use of multiple-locus variable-number tandem repeat analysis (MLVA) differentiated isolates that were indistinguishable by PFGE. Analysis of the allelic diversity of MLVA loci suggested that the O157:H7 isolates from this region were highly related. In contrast to O157:H7 isolates, a greater genotypic diversity was observed in the non-O157 isolates, resulting in 23 PFGE types and 14 MLVA types. The relevant non-O157 serotypes O8:H19, O75:H8, O111:H8 and O146:H21 represented 35.4% (23/65) of the recovered isolates. In particular, 18.5% (12/65) of all the isolates were serotype O75:H8, which was the most variable serotype by both PFGE and MLVA. The non-O157 isolates were predominantly recovered from sheep and were identified to harbor either one or two stx genes. Most non-O157 isolates were ehxA-positive (86.5%, 32/37) but only 10.8% (4/37) harbored eae. These findings indicate that zoonotic STEC with genotypes associated with human illness are present in animals on small farms within rural communities in the Culiacan Valley and emphasize the need for the development of control

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

    Science.gov (United States)

    Mughini-Gras, L; van Pelt, W; van der Voort, M; Heck, M; Friesema, I; Franz, E

    2018-02-01

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

  20. Molecular characterization of O157:H7, O26:H11 and O103:H2 Shiga toxin-producing Escherichia coli isolated from dairy products.

    Science.gov (United States)

    Douëllou, T; Delannoy, S; Ganet, S; Fach, P; Loukiadis, E; Montel, M-C; Sergentet-Thevenot, D

    2017-07-17

    Pathogenic Shiga toxin-producing E. coli (STEC) are recognized worldwide as environment and foodborne pathogens which can be transmitted by ingestion of ready-to-eat food such as raw milk-derived products. STEC show a prevalence rate in dairy products of 0.9%, yet comparably few outbreaks have been related to dairy products consumption. In this study, we used rt-qPCR to identify the virulence potential of O157, O26 and O103 STEC strains isolated from raw-milk dairy products by analyzing virulence-related gene frequencies and associations with O-island (OI) 44, OI-48, OI-50, OI-57, OI-71 and OI-122. Results showed that 100% of STEC strains investigated harbored genes associated with EHEC-related virulence profile patterns (eae and stx, with either espK, espV, ureD and/or Z2098). We also found similarities in virulence-related gene content between O157:H7 and O103:H2 dairy and non-dairy STEC strains, especially isolates from human cases. The O26:H11-serotype STEC strains investigated harbor the arcA-allele 2 gene associated with specific genetic markers. These profiles are associated with high-virulence seropathotype-A STEC. However, the low frequency of stx2 gene associated with absence of other virulence genes in dairy isolates of O26:H11 remains a promising avenue of investigation to estimate their real pathogenicity. All O26:H11 attaching-effacing E. coli (AEEC) strains carried CRISPRO26:H11SP_O26_E but not genetic markers espK, espV, ureD and/or Z2098 associated with the emerging potentially high-virulence "new French clone". These strains are potentially as "EHEC-like" strains because they may acquire (or have lost) stx gene. In this study, O157:H7, O103:H2 and O26:H11 STEC strains isolated from dairy products were assigned as potential pathogens. However, research now needs to investigate the impact of dairy product environment and dairy processing on the expression of their pathogenicity. Copyright © 2017. Published by Elsevier B.V.

  1. Microbiological analysis of pre-packed sweet basil (Ocimum basilicum) and coriander (Coriandrum sativum) leaves for the presence of Salmonella spp. and Shiga toxin-producing E. coli.

    Science.gov (United States)

    Delbeke, Stefanie; Ceuppens, Siele; Jacxsens, Liesbeth; Uyttendaele, Mieke

    2015-09-02

    Enteric pathogens, such as Salmonella spp. and pathogenic Escherichia coli, have been detected and associated with food borne outbreaks from (imported) fresh leafy herbs. Screening on imported herbs from South East Asian countries has been described. However, limited information on prevalence of these pathogens is available from other sourcing regions. Therefore, fresh pre-packed basil and coriander leaves from a Belgian trading company were investigated for the presence of Salmonella spp., Shiga toxin-producing E. coli (STEC), generic E. coli and coliforms. In total 592 samples were collected originating from Belgium, Israel and Cyprus during 2013-2014. Multiplex PCR followed by further culture confirmation was used for the detection of Salmonella spp. and STEC, whereas the Petrifilm Select E. coli and VRBL-agar were used, respectively, for the enumeration of E. coli and coliforms. Salmonella was detected in 10 out of 592 samples (25g) (1.7%; 5 from basil and 5 from coriander), of which two samples were sourced from Israel and eight from Cyprus. The presence of STEC was suspected in 11 out of 592 samples (25g) (1.9%; 3 basil and 8 coriander), due to the detection of stx and eae genes, of which one sample originated from Belgium, four from Israel and six from Cyprus. No STEC was isolated by culture techniques, but in three samples a serotype (O26, O103 or O111) with its most likely associated eae-variant (β or θ) was detected by PCR. Generic E. coli was enumerated in 108 out of 592 samples, whereby 55, 32 and 13 samples respectively between 10-100, 100-1000 and 1000-10,000cfu/g and 8 samples exceeding 10,000cfu/g. Coliforms were enumerated in all herb samples at variable levels ranging from 1.6 to 7.5logcfu/g. Further statistics indicate that the E. coli class (categorized by level) was significantly correlated with the presence of Salmonella (p<0.001) or STEC (p=0.019), while coliform counts were significant correlated with Salmonella (p<0.001), but not with

  2. Neutralization of toxicological activities of medically-relevant Bothrops snake venoms and relevant toxins by two polyvalent bothropic antivenoms produced in Peru and Brazil.

    Science.gov (United States)

    Estevao-Costa, Maria I; Gontijo, Silea S; Correia, Barbara L; Yarleque, Armando; Vivas-Ruiz, Dan; Rodrigues, Edith; Chávez-Olortegui, Carlos; Oliveira, Luciana S; Sanchez, Eladio F

    2016-11-01

    Snakebite envenoming is a neglected public pathology, affecting especially rural communities or isolated areas of tropical and subtropical Latin American countries. The parenteral administration of antivenom is the mainstay and the only validated treatment of snake bite envenoming. Here, we assess the efficacy of polyspecific anti-Bothrops serum (α-BS) produced in the Instituto Nacional de Salud (INS, Peru) and at the Fundação Ezequiel Dias (FUNED, Brazil), to neutralize the main toxic activities induced by five medically-relevant venoms of: Bothrops atrox, B. barnetti, and B. pictus from Peru, and the Brazilian B. jararaca and B. leucurus, all of them inhabiting different geographical locations. Protein electrophoretic patterns of these venoms showed significant differences in composition, number and intensity of bands. Another goal was to evaluate the efficacy and safety of lyophilized α-BS developed at INS to neutralize the detrimental effects of these venoms using in vivo and in vitro assays. The availability of lyophilized α-BS has relevant significance in its distribution to distant rural communities where the access to antivenom in health facilities is more difficult. Despite the fact that different antigen mixtures were used for immunization during antivenom production, our data showed high toxin-neutralizing activity of α-BS raised against Bothrops venoms. Moreover, the antivenom cross-reacted even against venoms not included in the immunization mixture. Furthermore, we have evaluated the efficacy of both α-BS to neutralize key toxic compounds belonging to the predominant protein families of Bothrops snakes. Most significantly, both α-BS cross-specifically neutralized the main toxicological activities e.g. lethality and hemorrhage induced by these venoms. Thus, our data indicate that both α-BS are equally effective to treat snake bite victims inflicted by Bothrops snakes particularly B. atrox, responsible for the largest numbers of human

  3. Implementation of Whole Genome Sequencing (WGS for Identification and Characterization of Shiga Toxin-Producing Escherichia coli (STEC in the United States

    Directory of Open Access Journals (Sweden)

    Rebecca L Lindsey

    2016-05-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC is an important foodborne pathogen capable of causing severe disease in humans. Rapid and accurate identification and characterization techniques are essential during outbreak investigations. Current methods for characterization of STEC are expensive and time-consuming. With the advent of rapid and cheap whole genome sequencing (WGS benchtop sequencers, the potential exists to replace traditional workflows with WGS. The aim of this study was to validate tools to do reference identification and characterization from WGS for STEC in a single workflow within an easy to use commercially available software platform. Publically available serotype, virulence, and antimicrobial resistance databases were downloaded from the Center for Genomic Epidemiology (CGE (www.genomicepidemiology.org and integrated into a genotyping plug-in with in silico PCR tools to confirm some of the virulence genes detected from WGS data. Additionally, down sampling experiments on the WGS sequence data were performed to determine a threshold for sequence coverage needed to accurately predict serotype and virulence genes using the established workflow. The serotype database was tested on a total of 228 genomes and correctly predicted from WGS for 96.1% of O serogroups and 96.5% of H serogroups identified by conventional testing techniques. A total of 59 genomes were evaluated to determine the threshold of coverage to detect the different WGS targets, 40 were evaluated for serotype and virulence gene detection and 19 for the stx gene subtypes. For serotype, 95% of the O and 100% of the H serogroups were detected at > 40x and ≥ 30x coverage, respectively. For virulence targets and stx gene subtypes, nearly all genes were detected at > 40x, though some targets were 100% detectable from genomes with coverage ≥20x. The resistance detection tool was 97% concordant with phenotypic testing results. With isolates sequenced to > 40x

  4. Survival and expression of acid resistance genes in Shiga toxin-producing Escherichia coli acid adapted in pineapple juice and exposed to synthetic gastric fluid.

    Science.gov (United States)

    Kim, G-H; Fratamico, P; Breidt, F; Oh, D-H

    2016-11-01

    The aim of this research was to determine the ability of non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups to survive with exposure to synthetic gastric fluid (SGF) after adaptation to pineapple juice (PJ) at room and refrigerated temperatures compared to E. coli O157:H7 and to examine the relative transcriptional expression of acid resistance (AR) genes, rpoS, gadA and adiA. Resistant and sensitive strains belonging to five different STEC serogroups (O26, O103, O104, O111 and O157; n = 10) were used in this study. All strains were adapted in PJ (pH 3·8) stored at 4 and 20°C for 24 h, and then the relative transcription levels of genes in all strains were quantified using a real-time quantitative-PCR assay. After adaptation in PJ, the STEC strains were exposed to SGF (pH 1·5 and 2·0) at 37°C for 2 h. Generally, the STEC adapted in PJ at 4°C displayed enhanced survival compared to acid adaptation in PJ at 20°C and nonadapted controls with exposure to SGF (P < 0·05). Moreover, resistant strains exhibited higher survival rates compared to sensitive strains (P < 0·05). Overall, adaptation at 4°C resulted in significantly (P < 0·05) enhanced gene expression levels in PJ, and transcript levels of gadA were higher than those of the rpoS and adiA genes. The up-regulation of AR genes due to adaptation in PJ at low temperature may increase STEC survival in acidic environments such as the gastrointestinal tract. Some non-O157 STEC strains, including serotypes O103:H2 and O111:H8, showed relatively high AR levels similar to those of STEC O157:H7. Induction of AR genes in acidic fruit juice, and potentially in other acidic foods may increase the risk of foodborne illness by non-O157 STEC serogroups. © 2016 The Society for Applied Microbiology.

  5. [Shiga toxin and tetanus toxin as a potential biologic weapon].

    Science.gov (United States)

    Toczyska, Izabela; Płusa, Tadeusz

    2015-09-01

    Toxins produced by the bacteria are of particular interest as potential cargo combat possible for use in a terrorist attack or war. Shiga toxin is usually produced by shiga toxigenic strains of Escherichia coli (STEC - shigatoxigenic Escherichia coli). To infection occurs mostly after eating contaminated beef. Clinical syndromes associated with Shiga toxin diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS - hemolytic uremic syndrome) or thrombotic thrombocytopenic purpura. Treatment is symptomatic. In HUS, in which mortality during an epidemic reaches 20%, extending the kidney injury dialysis may be necessary. Exposure to tetanus toxin produced by Clostridium tetani, resulting in the most generalized tetanus, characterized by increased muscle tension and painful contractions of individual muscle groups. In the treatment beyond symptomatic behavior (among others spasticity medications, anticonvulsants, muscle relaxants) is used tetanus antitoxin and antibiotics (metronidazole choice). A common complication is acute respiratory failure - then it is necessary to implement mechanical ventilation. © 2015 MEDPRESS.

  6. Development and evaluation of an indirect ELISA for detection of exfoliative toxin ExhA, ExhB or ExhC produced by Staphylococcus hyicus

    DEFF Research Database (Denmark)

    Andresen, Lars Ole

    1999-01-01

    , one from each of the 69 pig herds with outbreak of exudative epidermitis. Toxigenic S. hyicus were detected in 74% of the cases by ELISA. From each of the five cases, in which initially no toxigenic S. hyicus were found, a further 40 S. hyicus-like colonies were tested in ELISA. Testing of this number......Immunoblot analysis and enzyme-linked immunosorbent assay (ELISA) confirmed previous reports that the Staphylococcus hyicus exfoliative toxins ExhA and ExhB are metalloproteins, and further indicated that ExhC is also a metalloprotein. An indirect ELISA. was developed for the detection of toxigenic...... strains as an alternative method to the use of phage typing for selection of S. hyicus isolates to be used in autogenous vaccine against exudative epidermitis in pigs. The indirect ELISA was evaluated by investigating the presence of toxin among a total of 655 S. hyicus isolates from 69 pig skin samples...

  7. Marine and freshwater toxins.

    Science.gov (United States)

    Hungerford, James M

    2006-01-01

    In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods

  8. [Phalloidian toxins].

    Science.gov (United States)

    Larcan, A; Lamarche, M; Lambert, H

    1979-01-01

    The phalloidian toxins are very complex. The classification proposed by Wieland distinguishes between the various amatoxins and phallotoxins. The authors study successively: Methods of isolation, the general structure and chemical composition, their localization and concentration in mushrooms. This is an analytical study of the phallotoxins and amadoxins. Various experimental intoxication protocols using total extracts of the toxins purified with different doses and different animals have revealed the main signs of experimental intoxication with phallotoxins. This is characterized especially by hepatic and renal lesions. The phallotoxins have a more specific action on the cell membrane and metabolism. The amatoxins have a more specific action on the cell nucleus and protein synthesis. The action on DNA dependent RNA polymerases is particularly characteristic.

  9. Neuronal sensitivity to tetanus toxin requires gangliosides.

    Science.gov (United States)

    Williamson, L C; Bateman, K E; Clifford, J C; Neale, E A

    1999-08-27

    Tetanus toxin produces spastic paralysis in situ by blocking inhibitory neurotransmitter release in the spinal cord. Although di- and trisialogangliosides bind tetanus toxin, their role as productive toxin receptors remains unclear. We examined toxin binding and action in spinal cord cell cultures grown in the presence of fumonisin B(1), an inhibitor of ganglioside synthesis. Mouse spinal cord neurons grown for 3 weeks in culture in 20 microM fumonisin B(1) develop dendrites, axons, and synaptic terminals similar to untreated neurons, even though thin layer chromatography shows a greater than 90% inhibition of ganglioside synthesis. Absence of tetanus and cholera toxin binding by toxin-horseradish peroxidase conjugates or immunofluorescence further indicates loss of mono- and polysialogangliosides. In contrast to control cultures, tetanus toxin added to fumonisin B(1)-treated cultures does not block potassium-stimulated glycine release, inhibit activity-dependent uptake of FM1-43, or abolish immunoreactivity for vesicle-associated membrane protein, the toxin substrate. Supplementing fumonisin B(1)-treated cultures with mixed brain gangliosides completely restores the ability of tetanus toxin to bind to the neuronal surface and to block neurotransmitter release. These data demonstrate that fumonisin B(1) protects against toxin-induced synaptic blockade and that gangliosides are a necessary component of the receptor mechanism for tetanus toxin.

  10. Systematic comparison of single-chain Fv antibody-fusion toxin constructs containing Pseudomonas Exotoxin A or saporin produced in different microbial expression systems.

    Science.gov (United States)

    Della Cristina, Pietro; Castagna, Monica; Lombardi, Alessio; Barison, Erika; Tagliabue, Giovanni; Ceriotti, Aldo; Koutris, Ilias; Di Leandro, Luana; Giansanti, Francesco; Vago, Riccardo; Ippoliti, Rodolfo; Flavell, Sopsamorn U; Flavell, David J; Colombatti, Marco; Fabbrini, Maria Serena

    2015-02-13

    Antibodies raised against selected antigens over-expressed at the cell surface of malignant cells have been chemically conjugated to protein toxin domains to obtain immunotoxins (ITs) able to selectively kill cancer cells. Since latest generation immunotoxins are composed of a toxic domain genetically fused to antibody fragment(s) which confer on the IT target selective specificity, we rescued from the hydridoma 4KB128, a recombinant single-chain variable fragment (scFv) targeting CD22, a marker antigen expressed by B-lineage leukaemias and lymphomas. We constructed several ITs using two enzymatic toxins both able to block protein translation, one of bacterial origin (a truncated version of Pseudomonas exotoxin A, PE40) endowed with EF-2 ADP-ribosylation activity, the other being the plant ribosome-inactivating protein saporin, able to specifically depurinate 23/26/28S ribosomal RNA. PE40 was selected because it has been widely used for the construction of recombinant ITs that have already undergone evaluation in clinical trials. Saporin has also been evaluated clinically and has recently been expressed successfully at high levels in a Pichia pastoris expression system. The aim of the present study was to evaluate optimal microbial expression of various IT formats. An anti-CD22 scFv termed 4KB was obtained which showed the expected binding activity which was also internalized by CD22+ target cells and was also competed for by the parental monoclonal CD22 antibody. Several fusion constructs were designed and expressed either in E. coli or in Pichia pastoris and the resulting fusion proteins affinity-purified. Protein synthesis inhibition assays were performed on CD22+ human Daudi cells and showed that the selected ITs were active, having IC50 values (concentration inhibiting protein synthesis by 50% relative to controls) in the nanomolar range. We undertook a systematic comparison between the performance of the different fusion constructs, with respect to yields in

  11. A Sensitive Multiplex, Real-Time PCR Assay for Prospective Detection of Shiga Toxin-Producing Escherichia coli from Stool Samples Reveals Similar Incidences but Variable Severities of Non-O157 and O157 Infections in Northern California

    Science.gov (United States)

    Lefterova, Martina I.; Slater, Kathleen A.; Budvytiene, Indre; Dadone, Patricia A.

    2013-01-01

    Rapid and accurate detection of Shiga toxin-producing Escherichia coli (STEC) of all serotypes from patients with diarrhea is critical for medical management and for the prevention of ongoing transmission. In this prospective study, we assessed the performance of a multiplex, real-time PCR assay targeting stx1 and stx2 for the detection of O157 and non-O157 STEC in diarrheal stool samples enriched in Gram-negative broth. We show that the assay is 100% sensitive (95% confidence interval [CI], 89.1% to 100%) and 98.5% specific (95% CI, 90.6% to 99.9%) based on a panel of 40 known STEC-positive specimens and 65 known negative specimens. During a 2-year postvalidation period, the assay detected more positive samples from patients in northern California than did culture and PCR testing performed at a public health reference laboratory, with a positive predictive value of 95.6% (95% CI, 87.6% to 99.1%). Serotyping data showed an incidence rate of 51.2% for non-O157 STEC strains, with 5.8% of patients (1/17) with non-O157 strains and 42.9% (6/14) with O157 strains (P = 0.03) developing hemolytic-uremic syndrome. The findings from this study underscore the recommendations of the CDC for laboratories to test all diarrheal stool samples from patients with acute community-acquired diarrhea for non-O157 STEC in addition to the O157 serotype by using a sensitive assay. Additionally, a survey of 17 clinical laboratories in northern California demonstrated that nearly 50% did not screen all stool specimens for the presence of Shiga toxins, indicating that many clinical microbiology laboratories still do not routinely screen all stool specimens for the presence of Shiga toxins as recommended in the 2009 CDC guidelines. PMID:23843484

  12. Effect of supplementary glycerin on milk composition and heat stability in dairy goats.

    Science.gov (United States)

    Thoh, Deela; Pakdeechanuan, Patcharin; Chanjula, Pin

    2017-12-01

    This experiment was studied the effects of various levels of crude glycerin (CG) in dairy goat diet on daily intake, milk yield, milk composition, some physical properties and some quality changes of goat milk after sterilization. Twelve 75% Saanen dairy goats (body weight = 49±3 kg; days in milk = 60±12 d) were randomly assigned in a completely randomized design to evaluate the effects of three experimental diets consisting of 0%, 5%, and 10% CG (dry matter basis) which were formulated to meet or exceed the nutrient requirements of goats. Experimental dairy goats were evaluated for feed and milk yield. Milk samples were analyzed for their composition, including fatty acids, casein profile, fat globule size, and color, and were sterilized to evaluate milk heat stability. There were no significant differences between 0% and 5% CG treatments infeed. Increasing CG supplementation from 0% to 5% increased milk yield from 2.38±0.12 to 2.64±0.23 kg/goat/d. In addition, milk samples from 5% CG treatment had the highest total solids, fat content and lactose content, and largest fat globule size. Increasing CG to 10% resulted in a decrease in milk fat. After sterilizing at 116°C, F 0 = 3 min, goat milk samples from 5% CG treatment had slightly higher sediment content and comparatively higher degree of browning. Considering milk yield, milk fat content and quality of sterilized milk, 5% CG supplementation in a total mixed ration has a potential for implementation in dairy goats.

  13. Effect of supplementary glycerin on milk composition and heat stability in dairy goats

    Directory of Open Access Journals (Sweden)

    Deela Thoh

    2017-12-01

    Full Text Available Objective This experiment was studied the effects of various levels of crude glycerin (CG in dairy goat diet on daily intake, milk yield, milk composition, some physical properties and some quality changes of goat milk after sterilization. Methods Twelve 75% Saanen dairy goats (body weight = 49±3 kg; days in milk = 60±12 d were randomly assigned in a completely randomized design to evaluate the effects of three experimental diets consisting of 0%, 5%, and 10% CG (dry matter basis which were formulated to meet or exceed the nutrient requirements of goats. Experimental dairy goats were evaluated for feed and milk yield. Milk samples were analyzed for their composition, including fatty acids, casein profile, fat globule size, and color, and were sterilized to evaluate milk heat stability. Results There were no significant differences between 0% and 5% CG treatments infeed. Increasing CG supplementation from 0% to 5% increased milk yield from 2.38±0.12 to 2.64±0.23 kg/goat/d. In addition, milk samples from 5% CG treatment had the highest total solids, fat content and lactose content, and largest fat globule size. Increasing CG to 10% resulted in a decrease in milk fat. After sterilizing at 116°C, F0 = 3 min, goat milk samples from 5% CG treatment had slightly higher sediment content and comparatively higher degree of browning. Conclusion Considering milk yield, milk fat content and quality of sterilized milk, 5% CG supplementation in a total mixed ration has a potential for implementation in dairy goats.

  14. A qPCR Assay to Detect and Quantify Shiga Toxin-Producing E. coli (STEC in Cattle and on Farms: A Potential Predictive Tool for STEC Culture-Positive Farms

    Directory of Open Access Journals (Sweden)

    Karen Verstraete

    2014-03-01

    Full Text Available Shiga toxin-producing E. coli (STEC, of various serogroups harboring the intimin gene, form a serious threat to human health. They are asymptomatically carried by cattle. In this study, a quantitative real-time PCR (qPCR method was developed as a molecular method to detect and quantify Shiga toxin genes stx1 and stx2 and the intimin gene eae. Subsequently, 59 fecal samples from six farms were tested using qPCR and a culture method as a reference. Three farms had contaminated animals as demonstrated by the culture method. Culture-positive farms showed moderate significantly higher stx prevalences than culture-negative farms (p = 0.05. This is the first study which showed preliminary results that qPCR can predict STEC farm contamination, with a specificity of 77% and a sensitivity of 83%, as compared with the culture method. Furthermore, the presence or quantity of stx genes in feces was not correlated to the isolation of STEC from the individual animal. Quantitative data thus did not add value to the results. Finally, the detection of both stx and eae genes within the same fecal sample or farm using qPCR was not correlated with the isolation of an eae-harboring STEC strain from the respective sample or farm using the culture method.

  15. A qPCR assay to detect and quantify Shiga toxin-producing E. coli (STEC) in cattle and on farms: a potential predictive tool for STEC culture-positive farms.

    Science.gov (United States)

    Verstraete, Karen; Van Coillie, Els; Werbrouck, Hadewig; Van Weyenberg, Stephanie; Herman, Lieve; Del-Favero, Jurgen; De Rijk, Peter; De Zutter, Lieven; Joris, Maria-Adelheid; Heyndrickx, Marc; De Reu, Koen

    2014-03-27

    Shiga toxin-producing E. coli (STEC), of various serogroups harboring the intimin gene, form a serious threat to human health. They are asymptomatically carried by cattle. In this study, a quantitative real-time PCR (qPCR) method was developed as a molecular method to detect and quantify Shiga toxin genes stx1 and stx2 and the intimin gene eae. Subsequently, 59 fecal samples from six farms were tested using qPCR and a culture method as a reference. Three farms had contaminated animals as demonstrated by the culture method. Culture-positive farms showed moderate significantly higher stx prevalences than culture-negative farms (p = 0.05). This is the first study which showed preliminary results that qPCR can predict STEC farm contamination, with a specificity of 77% and a sensitivity of 83%, as compared with the culture method. Furthermore, the presence or quantity of stx genes in feces was not correlated to the isolation of STEC from the individual animal. Quantitative data thus did not add value to the results. Finally, the detection of both stx and eae genes within the same fecal sample or farm using qPCR was not correlated with the isolation of an eae-harboring STEC strain from the respective sample or farm using the culture method.

  16. Evaluating the efficacy of beef slaughter line interventions by quantifying the six major non-O157 Shiga toxin producing Escherichia coli serogroups using real-time multiplex PCR.

    Science.gov (United States)

    Kanankege, Kaushi S T; Anklam, Kelly S; Fick, Catherine M; Kulow, Megan J; Kaspar, Charles W; Ingham, Barbara H; Milkowski, Andrew; Döpfer, Dörte

    2017-05-01

    Six major Shiga toxin producing Escherichia coli (STEC) serogroups: O26, O103, O145, O111, O121, and O45 have been declared as adulterants in federally inspected raw beef in the USA effective June 4th, 2012 in addition to the routinely tested STEC O157: H7. This study tests a real-time multiplex PCR assay and pooling of the samples to optimize the detection and quantification (prevalence and contamination) of six major non-O157 STEC, regardless of possessing Shiga toxins. To demonstrate the practicality, one large-scale slaughter plant (Plant LS) and one small-scale slaughter plant (Plant SS) located in the Mid-Western USA were sampled, in 2011, before the establishment of 2013 USDA laboratory protocols. Carcasses were sampled at consecutive intervention stations and beef trimmings were collected at the end of the fabrication process. Plant SS had marginally more contaminated samples than Plant LS (p-value 0.08). The post-hide removal wash, steam pasteurization, and lactic acid (≤5%) spray used in Plant LS seemed to reduce the six serogroups effectively, compared to the hot-water wash and 7-day chilling at Plant SS. Compared to the culture isolation methods, quantification of the non-O157 STEC using real-time PCR may be an efficient way to monitor the efficacy of slaughter line interventions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Effect of CO2 on growth and toxicity of Alexandrium tamarense from the East China Sea, a major producer of paralytic shellfish toxins.

    Science.gov (United States)

    Pang, Min; Xu, Jintao; Qu, Pei; Mao, Xuewei; Wu, Zhenxing; Xin, Ming; Sun, Ping; Wang, Zongxing; Zhang, Xuelei; Chen, Hongju

    2017-09-01

    In recent decades, the frequency and intensity of harmful algal blooms (HABs), as well as a profusion of toxic phytoplankton species, have significantly increased in coastal regions of China. Researchers attribute this to environmental changes such as rising atmospheric CO2 levels. Such addition of carbon into the ocean ecosystem can lead to increased growth, enhanced metabolism, and altered toxicity of toxic phytoplankton communities resulting in serious human health concerns. In this study, the effects of elevated partial pressure of CO2 (pCO2) on the growth and toxicity of a strain of Alexandrium tamarense (ATDH) widespread in the East and South China Seas were investigated. Results of these studies showed a higher specific growth rate (0.31±0.05day-1) when exposed to 1000μatm CO2, (experimental), with a corresponding density of (2.02±0.19)×107cellsL-1, that was significantly larger than cells under 395μatm CO2(control). These data also revealed that elevated pCO2 primarily affected the photosynthetic properties of cells in the exponential growth phase. Interestingly, measurement of the total toxin content per cell was reduced by half under elevated CO2 conditions. The following individual toxins were measured in this study: C1, C2, GTX1, GTX2, GTX3, GTX4, GTX5, STX, dcGTX2, dcGTX3, and dcSTX. Cells grown in 1000μatm CO2 showed an overall decrease in the cellular concentrations of C1, C2, GTX2, GTX3, GTX5, STX, dcGTX2, dcGTX3, and dcSTX, but an increase in GTX1 and GTX4. Total cellular toxicity per cell was measured revealing an increase of nearly 60% toxicity in the presence of elevated CO2 compared to controls. This unusual result was attributed to a significant increase in the cellular concentrations of the more toxic derivatives, GTX1 and GTX4.Taken together; these findings indicate that the A. tamarense strain ATDH isolated from the East China Sea significantly increased in growth and cellular toxicity under elevated pCO2 levels. These data may

  18. DAB389IL-2 recombinant fusion toxin effect on lymphocyte- and macrophage-producing cytokine subpopulation cells in experimentally induced demyelinating disease in mice.

    Science.gov (United States)

    Bhopale, Mahendra K; Hilliard, Brendan; Constantinescu, Cris S; Phillips, S Michael; Rostami, Abdolmohamad

    2017-09-20

    We have reported previously that DAB389IL-2 recombinant fusion toxin targets IL-2R bearing CD4(+) cells, and suppresses demyelinating disease in acute (A) - and chronic (C) - experimental autoimmune encephalomyelitis (EAE) animal models of multiple sclerosis. The present study was undertaken to investigate the effect of DAB389IL-2 treatment on various cytokine-secreting cell populations in A-EAE and C-EAE mice. The effects of DAB389IL-2 at doses of 200-, 800-, or 1600 kU administered i.v. on days 11-13 and 15 on the clinical score and cytokine-secreting cell populations were examined using flow cytometry. C-EAE mice treated with 1600kU DAB389IL-2, but not A-EAE mice treated with 800 kU had significantly reduced disease. The CD3+CD25+ sub-population in spleens and spinal cords of A-EAE mice treated with 800 kU DAB389IL-2 a was increased, whereas in C-EAE mice treated with 1600 kU this population was increased. DAB389IL-2 treatment reduced CD3(+)CD4(+), CD3(+)CD8(+), CD4(+)CD8(+), CD3(+)IL-2(+), CD3(+)IFN-γ(+) and CD3(+)TNF-α(+) T cell subpopulations in the spinal cord in A-EAE, and C-EAE mice on day 16. CD11b+ macrophages that were IL-2-, IFN-γ-, and TNF-α- positive were reduced in A-EAE mice. DAB389IL-2 treatment reduced CD19(+) B-cells positive for IL-2 or CD11b(+) in the spinal cord in acute and chronic disease. DAB389IL-2 treatment also reduced lymph node CD3(+)CD8(+), CD4(+)CD8(+), CD3(+)CD25(+) populations on day 16, and lymph node CD3(+)IL-10(+) and peripheral blood CD3(+)CD25(+) populations on day 24. Our study demonstrates that DAB389IL-2 fusion toxin suppresses EAE in a dose-dependent manner, and alters inflammatory cell sub-populations during disease development.

  19. Identification of the cellular receptor of Clostridium spiroforme toxin.

    Science.gov (United States)

    Papatheodorou, Panagiotis; Wilczek, Claudia; Nölke, Thilo; Guttenberg, Gregor; Hornuss, Daniel; Schwan, Carsten; Aktories, Klaus

    2012-04-01

    Clostridium spiroforme produces the binary actin-ADP-ribosylating toxin CST (C. spiroforme toxin), which has been proposed to be responsible for diarrhea, enterocolitis, and eventually death, especially in rabbits. Here we report on the recombinant production of the enzyme component (CSTa) and the binding component (CSTb) of C. spiroforme toxin in Bacillus megaterium. By using the recombinant toxin components, we show that CST enters target cells via the lipolysis-stimulated lipoprotein receptor (LSR), which has been recently identified as the host cell receptor of the binary toxins Clostridium difficile transferase (CDT) and Clostridium perfringens iota toxin. Microscopic studies revealed that CST, but not the related Clostridium botulinum C2 toxin, colocalized with LSR during toxin uptake and traffic to endosomal compartments. Our findings indicate that CST shares LSR with C. difficile CDT and C. perfringens iota toxin as a host cell surface receptor.

  20. Towards an understanding of the role of Clostridium perfringens toxins in human and animal disease

    Science.gov (United States)

    Uzal, Francisco A; Freedman, John C; Shrestha, Archana; Theoret, James R; Garcia, Jorge; Awad, Milena M; Adams, Vicki; Moore, Robert J; Rood, Julian I; McClane, Bruce A

    2014-01-01

    Clostridium perfringens uses its arsenal of >16 toxins to cause histotoxic and intestinal infections in humans and animals. It has been unclear why this bacterium produces so many different toxins, especially since many target the plasma membrane of host cells. However, it is now established that C. perfringens uses chromosomally encoded alpha toxin (a phospholipase C) and perfringolysin O (a pore-forming toxin) during histotoxic infections. In contrast, this bacterium causes intestinal disease by employing toxins encoded by mobile genetic elements, including C. perfringens enterotoxin, necrotic enteritis toxin B-like, epsilon toxin and beta toxin. Like perfringolysin O, the toxins with established roles in intestinal disease form membrane pores. However, the intestinal disease-associated toxins vary in their target specificity, when they are produced (sporulation vs vegetative growth), and in their sensitivity to intestinal proteases. Producing many toxins with diverse characteristics likely imparts virulence flexibility to C. perfringens so it can cause an array of diseases. PMID:24762309

  1. Toxins of Amanita phalloides.

    Science.gov (United States)

    Vetter, J

    1998-01-01

    The most poisonous mushroom toxins are produced by Amanita phalloides (death cap). The occurrence and chemistry of three groups of toxins (amatoxins, phallotoxins and virotoxins) are summarized. The concentration and distribution of toxins in certain species are variable, with the young fruit body containing lower, and the well-developed fungus higher concentrations, but there is a high variability among specimens collected in the same region. Regarding phallotoxins, the volva (the ring) is the most poisonous. The most important biochemical effect of amatoxins is the inhibition of RNA polymerases (especially polymerase II). This interaction leads to a tight complex and the inhibition is of a non-competitive type. Non-mammalian polymerases show little sensitivity to amanitins. The amatoxins cause necrosis of the liver, also partly in the kidney, with the cellular changes causing the fragmentation and segregation of all nuclear components. Various groups of somatic cells of emanation resistance have been isolated, including from a mutant of Drosophila melanogaster. The phallotoxins stimulate the polymerization of G-actin and stabilize the F-actin filaments. The interaction of phallotoxins occurs via the small, 15-membered ring, on the left side of the spatial formula. The symptoms of human poisoning and the changes in toxin concentrations in different organs are summarized. Conventional therapy includes: (1) stabilization of patient's condition with the correction of hypoglycaemia and electrolytes; (2) decontamination; and (3) chemotherapy with different compounds. Finally, certain antagonists and protective compounds are reviewed, bearing in mind that today these have more of a theoretical than a practical role.

  2. Shigella Sonnei and Shiga Toxin

    Centers for Disease Control (CDC) Podcasts

    2016-07-28

    Katherine Lamba, an infectious disease epidemiologist with the California Department of Public Health, discusses Shiga Toxin producing Shigella sonnei.  Created: 7/28/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 7/28/2016.

  3. Prevalence of Shiga toxin Producing Escherichia coli, Salmonella enterica and Listeria monocytogenes at Public Access Watershed Sites in a California Central Coast Agricultural Region

    Directory of Open Access Journals (Sweden)

    Michael B Cooley

    2014-03-01

    Full Text Available Produce contaminated with enteric pathogens is a major source of foodborne illness in the United States. Lakes, streams, rivers, and ponds were sampled with Moore swabs bi-monthly for over two years at 30 locations in the vicinity of a leafy green growing region on the Central California Coast and screened for Shiga toxin producing Escherichia coli (STEC, Salmonella enterica, and Listeria monocytogenes to evaluate the prevalence and persistence of pathogen subtypes. The prevalence of STEC from 1,386 samples was 11%; 110 samples (8% contained E. coli O157:H7 with the highest prevalence occurring close to cattle operations. Non-O157 STEC isolates represented major clinical O-types and 57% contained both shiga toxin types 1 and 2 and intimin. Multiple Locus Variable Number Tandem Repeat Analysis of STEC isolates indicated prevalent strains during the period of study. Notably, Salmonella was present at high levels throughout the sampling region with 65% prevalence in 1,405 samples resulting in 996 isolates with slightly lower prevalence in late autumn. There were 2, 8 and 14 sites that were Salmonella-positive over 90%, 80% and 70% of the time, respectively. The serotypes identified most often were 6,8:d:-, Typhimurium, and Give. Interestingly, analysis by Pulsed Field Gel Electrophoresis indicated persistence and transport of pulsotypes in the region over several years. In this original study of L. monocytogenes in the region prevalence was 43% of 1,405 samples resulting in 635 individual isolates. Over 85% of the isolates belonged to serotype 4b with serotypes 1/2a, 1/2b, 3a, 4d with 4e representing the rest, and there were 12 and 2 sites that were positive over 50% and 80% of the time, respectively. Although surface water is not directly used for irrigation in this region, transport to the produce can occur by other means. This environmental survey assesses initial contamination levels towards an understanding of transport leading to produce

  4. Neutralising Antibodies against Ricin Toxin

    OpenAIRE

    Julie Prigent; Laetitia Panigai; Patricia Lamourette; Didier Sauvaire; Karine Devilliers; Marc Plaisance; Hervé Volland; Christophe Créminon; Stéphanie Simon

    2011-01-01

    The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this pur...

  5. Botulinum toxin for treatment of blepharospasm and hemifacial spasm

    Directory of Open Access Journals (Sweden)

    Soltanzadeh A

    1997-04-01

    Full Text Available Botulinum toxin produced by Clostridium butolinum in one of the most fatal toxins known. Botulism is the name given to condition produced by this toxin. In recent years the diluted form of this toxin has been produced in injection form and used for treatment of hemifacial spasm and blepharospasm. This toxin blocks neuromuscular junction and inhibits acetylcholine release. In this article we reported 36 patients suffering from hemifacial & blepharospasm treated by injections of botulinum A toxin. 85 to 90 percent of patients responded well. The common complications of this drug were ptosis, hemifacial paresis, burning of the mouth and discoloration of the injection site. Generally speaking the patients preferred this toxin to taking oral medications which were less effective.

  6. INVESTIGATOIN OF CYANOBACTERIA TOXINS IN WATER

    Science.gov (United States)

    Introduction:Approximately 80 alkaloid and cyclic peptide toxins produced by various freshwater and marine cyanobacteria (blue-green algae) have been identified and their structures determined. The U. S. Environmental Protection Agency has identified two neurotoxin alkalo...

  7. Non-Toxin-Producing Bacillus cereus Strains Belonging to the B. anthracis Clade Isolated from the International Space Station.

    Science.gov (United States)

    Venkateswaran, Kasthuri; Singh, Nitin K; Checinska Sielaff, Aleksandra; Pope, Robert K; Bergman, Nicholas H; van Tongeren, Sandra P; Patel, Nisha B; Lawson, Paul A; Satomi, Masataka; Williamson, Charles H D; Sahl, Jason W; Keim, Paul; Pierson, Duane; Perry, Jay

    2017-01-01

    In an ongoing Microbial Observatory investigation of the International Space Station (ISS), 11 Bacillus strains (2 from the Kibo Japanese experimental module, 4 from the U.S. segment, and 5 from the Russian module) were isolated and their whole genomes were sequenced. A comparative analysis of the 16S rRNA gene sequences of these isolates showed the highest similarity (>99%) to the Bacillus anthracis-B. cereus-B. thuringiensis group. The fatty acid composition, polar lipid profile, peptidoglycan type, and matrix-assisted laser desorption ionization-time of flight profiles were consistent with the B. cereus sensu lato group. The phenotypic traits such as motile rods, enterotoxin production, lack of capsule, and resistance to gamma phage/penicillin observed in ISS isolates were not characteristics of B. anthracis. Whole-genome sequence characterizations showed that ISS strains had the plcR non-B. anthracis ancestral "C" allele and lacked anthrax toxin-encoding plasmids pXO1 and pXO2, excluding their identification as B. anthracis. The genetic identities of all 11 ISS isolates characterized via gyrB analyses arbitrarily identified them as members of the B. cereus group, but traditional DNA-DNA hybridization (DDH) showed that the ISS isolates are similar to B. anthracis (88% to 90%) but distant from the B. cereus (42%) and B. thuringiensis (48%) type strains. The DDH results were supported by average nucleotide identity (>98.5%) and digital DDH (>86%) analyses. However, the collective phenotypic traits and genomic evidence were the reasons to exclude the ISS isolates from B. anthracis. Nevertheless, multilocus sequence typing and whole-genome single nucleotide polymorphism analyses placed these isolates in a clade that is distinct from previously described members of the B. cereus sensu lato group but closely related to B. anthracis. IMPORTANCE The International Space Station Microbial Observatory (Microbial Tracking-1) study is generating a microbial

  8. Retrograde trafficking of AB₅ toxins: mechanisms to therapeutics.

    Science.gov (United States)

    Mukhopadhyay, Somshuvra; Linstedt, Adam D

    2013-10-01

    Bacterial AB5 toxins are a clinically relevant class of exotoxins that include several well-known members such as Shiga, cholera, and pertussis toxins. Infections with toxin-producing bacteria cause devastating human diseases that affect millions of individuals each year and have no definitive medical treatment. The molecular targets of AB5 toxins reside in the cytosol of infected cells, and the toxins reach the cytosol by trafficking through the retrograde membrane transport pathway that avoids degradative late endosomes and lysosomes. Focusing on Shiga toxin as the archetype member, we review recent advances in understanding the molecular mechanisms involved in the retrograde trafficking of AB5 toxins and highlight how these basic science advances are leading to the development of a promising new therapeutic approach based on inhibiting toxin transport.

  9. Rapid and simple method by combining FTA™ card DNA extraction with two set multiplex PCR for simultaneous detection of non-O157 Shiga toxin-producing Escherichia coli strains and virulence genes in food samples.

    Science.gov (United States)

    Kim, S A; Park, S H; Lee, S I; Ricke, S C

    2017-12-01

    The aim of this research was to optimize two multiplex polymerase chain reaction (PCR) assays that could simultaneously detect six non-O157 Shiga toxin-producing Escherichia coli (STEC) as well as the three virulence genes. We also investigated the potential of combining the FTA™ card-based DNA extraction with the multiplex PCR assays. Two multiplex PCR assays were optimized using six primer pairs for each non-O157 STEC serogroup and three primer pairs for virulence genes respectively. Each STEC strain specific primer pair only amplified 155, 238, 321, 438, 587 and 750 bp product for O26, O45, O103, O111, O121 and O145 respectively. Three virulence genes were successfully multiplexed: 375 bp for eae, 655 bp for stx1 and 477 bp for stx2. When two multiplex PCR assays were validated with ground beef samples, distinctive bands were also successfully produced. Since the two multiplex PCR examined here can be conducted under the same PCR conditions, the six non-O157 STEC and their virulence genes could be concurrently detected with one run on the thermocycler. In addition, all bands clearly appeared to be amplified by FTA card DNA extraction in the multiplex PCR assay from the ground beef sample, suggesting that an FTA card could be a viable sampling approach for rapid and simple DNA extraction to reduce time and labour and therefore may have practical use for the food industry. Two multiplex polymerase chain reaction (PCR) assays were optimized for discrimination of six non-O157 Shiga toxin-producing Escherichia coli (STEC) and identification of their major virulence genes within a single reaction, simultaneously. This study also determined the successful ability of the FTA™ card as an alternative to commercial DNA extraction method for conducting multiplex STEC PCR assays. The FTA™ card combined with multiplex PCR holds promise for the food industry by offering a simple and rapid DNA sample method for reducing time, cost and labour for detection of STEC in

  10. Comparison of eight different agars for the recovery of clinically relevant non-O157 Shiga toxin-producing Escherichia coli from baby spinach, cilantro, alfalfa sprouts and raw milk.

    Science.gov (United States)

    Kase, Julie A; Maounounen-Laasri, Anna; Son, Insook; Lin, Andrew; Hammack, Thomas S

    2015-04-01

    The FDA Bacteriological Analytical Manual (BAM) Chapter 4a recommends several agars for isolating non-O157 Shiga toxin-producing Escherichia coli (STEC); not all have been thoroughly tested for recovering STECs from food. Using E. coli strains representing ten clinically relevant O serogroups (O26, O45, O91, O103, O104, O111, O113, O121, O128, O145) in artificially-contaminated fresh produce--bagged baby spinach, alfalfa sprouts, cilantro, and raw milk--we evaluated the performance of 8 different agars. Performance was highly dependent upon strain used and the presence of inhibitors, but not necessarily dependent on food matrix. Tellurite resistant-negative strains, O91:-, O103:H6, O104:H21, O113:H21, and O128, grew poorly on CHROMagar STEC, Rainbow agar O157, and a modified Rainbow O157 (mRB) agar. Although adding washed sheep's blood to CHROMagar STEC and mRB agars improved overall performance; however, this also reversed the inhibition of non-target bacteria provided by original formulations. Variable colony coloration made selecting colonies from Rainbow agar O157 and mRB agars difficult. Study results support a strategy using inclusive agars (e.g. L-EMB, SHIBAM) in combination with selective agars (R & F E. coli O157:H7, CHROMagar STEC) to allow for recovery of the most STECs while increasing the probability of recovering STEC in high bacterial count matrices. Published by Elsevier Ltd.

  11. Bordetella Adenylate Cyclase-Hemolysin Toxins

    Science.gov (United States)

    Guiso, Nicole

    2017-01-01

    Adenylate cyclase-hemolysin toxin is secreted and produced by three classical species of the genus Bordetella: Bordetella pertussis, B. parapertussis and B. bronchiseptica. This toxin has several properties such as: (i) adenylate cyclase activity, enhanced after interaction with the eukaryotic protein, calmodulin; (ii) a pore-forming activity; (iii) an invasive activity. It plays an important role in the pathogenesis of these Bordetella species responsible for whooping cough in humans or persistent respiratory infections in mammals, by modulating host immune responses. In contrast with other Bordetella toxins or adhesins, lack of (or very low polymorphism) is observed in the structural gene encoding this toxin, supporting its importance as well as a potential role as a vaccine antigen against whooping cough. In this article, an overview of the investigations undertaken on this toxin is presented. PMID:28892012

  12. Prevalence of shiga toxin-producing Escherichia coli stx1, stx2, eaeA, and rfbE genes and survival of E. coli O157:H7 in manure from organic and low-input conventional dairy farms

    NARCIS (Netherlands)

    Franz, E.; Klerks, M.M.; Vos, de O.J.; Termorshuizen, A.J.; Bruggen, van A.H.C.

    2007-01-01

    Manure samples were collected from 16 organic (ORG) and 9 low-input conventional (LIC) Dutch dairy farms during August and September 2004 to determine the prevalence of the STEC virulence genes stx(1) (encoding Shiga toxin 1), stx(2) (encoding Shiga toxin 2), and eaeA (encoding intimin), as well as

  13. Risk Assessment of Shellfish Toxins

    Directory of Open Access Journals (Sweden)

    Rex Munday

    2013-11-01

    Full Text Available Complex secondary metabolites, some of which are highly toxic to mammals, are produced by many marine organisms. Some of these organisms are important food sources for marine animals and, when ingested, the toxins that they produce may be absorbed and stored in the tissues of the predators, which then become toxic to animals higher up the food chain. This is a particular problem with shellfish, and many cases of poisoning are reported in shellfish consumers each year. At present, there is no practicable means of preventing uptake of the toxins by shellfish or of removing them after harvesting. Assessment of the risk posed by such toxins is therefore required in order to determine levels that are unlikely to cause adverse effects in humans and to permit the establishment of regulatory limits in shellfish for human consumption. In the present review, the basic principles of risk assessment are described, and the progress made toward robust risk assessment of seafood toxins is discussed. While good progress has been made, it is clear that further toxicological studies are required before this goal is fully achieved.

  14. General Aspects and Recent Advances on Bacterial Protein Toxins

    Science.gov (United States)

    Lemichez, Emmanuel; Barbieri, Joseph T.

    2013-01-01

    Bacterial pathogens produce protein toxins to influence host–pathogen interactions and tip the outcome of these encounters toward the benefit of the pathogen. Protein toxins modify host-specific targets through posttranslational modifications (PTMs) or noncovalent interactions that may inhibit or activate host cell physiology to benefit the pathogen. Recent advances have identified new PTMs and host targets for toxin action. Understanding the mechanisms of toxin action provides a basis to develop vaccines and therapies to combat bacterial pathogens and to develop new strategies to use toxin derivatives for the treatment of human disease. PMID:23378599

  15. Effect of seasonal variation on some physical properties and heat stability of milk subjected to ultra-high temperature and in-container sterilisation.

    Science.gov (United States)

    Chen, Biye; Grandison, Alistair S; Lewis, Michael J

    2015-08-15

    Heat stability was evaluated in bulk raw milk, collected throughout the year and subjected to ultra-high temperature (UHT) or in-container sterilisation, with and without added calcium chloride (2mM), disodium hydrogen phosphate (DSHP, 10mM) and trisodium citrate (TSC, 10mM). More sediment was observed following in-container sterilisation (0.24%) compared with UHT (0.19%). Adding CaCl2 made the milk more unstable to UHT than to in-container sterilisation, while adding DSHP and TSC made the milk more unstable during in-container sterilisation than to UHT processing, although TSC addition increased the sediment formed by UHT processing. Better heat stability was observed in autumn and winter than in spring and summer following UHT. However, following in-container sterilisation, samples with added stabilising salts showed significantly improved heat stability in autumn, whereas with added CaCl2, the best heat stability was observed in spring. No correlation was found between urea and heat stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Toxin production in Dinophysis and the fate of these toxins in marine mussels

    DEFF Research Database (Denmark)

    Nielsen, Lasse Tor

    Diarrhetic shellfish poisoning (DSP) poses a considerable threat to food safety and to the economy of shellfish fishers and farmers in many parts of the world. Thousands of DSP intoxications have been reported, and bivalve harvesting can sometimes be closed down several months in a row. The toxins...... are primarily produced by the marine mixotrophic dinoflagellates Dinophysis spp., known to occur in most parts of the world. Dinophysis can, along with other planktonic organisms, be consumed by filter-feeding bivalves, and thus the toxins can accumulate. Dinophysis can produce the three toxin groups, okadaic...... acid (OA), dinophysistoxins (DTX) and pectenotoxins (PTX) – the latter two in a few different isomers. Toxin profiles, as well as cellular toxin quotas, vary tremendously between Dinophysis populations in situ, both within and between species, and the toxicity of a Dinophysis population is obviously...

  17. Comparison of the fate of the top six non-O157 shiga-toxin producing Escherichia coli (STEC) and E. coli O157:H7 during the manufacture of dry fermented sausages.

    Science.gov (United States)

    Balamurugan, S; Ahmed, Rafath; Gao, Anli; Strange, Phil

    2017-10-16

    The study examined the relative fate of the top six non-O157 shiga-toxin producing Escherichia coli (STEC) and E. coli O157:H7 during the manufacture of dry fermented sausages (DFS). Three separate batches of sausages containing a five-strain cocktail for each serogroup and uninoculated control were manufactured and subjected to identical fermentation, maturation and dry curing conditions. Changes in physicochemical properties and inoculated STEC numbers were enumerated during the DFS production stages and log reduction and log reduction rates were calculated. Inoculation of very high concentrations (8logCFUg-1) of STEC in the sausage batter did not significantly (P>0.05) affect the changes in the pH, aw, moisture, protein, fat content compared to the uninoculated DFS. There was a significant (P0.05) from each other. These results indicate that the lethality of DFS production processes observed against E. coli O157:H7 would result in a similar inactivation of the top six non-O157 STEC. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  18. Development of a High Resolution Virulence Allelic Profiling (HReVAP Approach Based on the Accessory Genome of Escherichia coli to Characterize Shiga-toxin Producing E. coli (STEC

    Directory of Open Access Journals (Sweden)

    Valeria eMichelacci

    2016-02-01

    Full Text Available Shiga-toxin producing Escherichia coli (STEC strains possess a large accessory genome composed of virulence genes existing in multiple allelic variants, which sometimes segregate with specific STEC subpopulations. We analyzed the allelic variability of 91 virulence genes of STEC by Real Time PCR followed by melting curves analysis in 713 E. coli strains including 358 STEC. The 91 genes investigated were located on the LEE, OI-57 and OI-122 pathogenicity islands and displayed a total of 476 alleles in the study population. The combinations of the 91 alleles of each strain were termed allelic signatures and used to perform cluster analyses. We termed such an approach High Resolution Virulence Allelic Profiling (HReVAP and used it to investigate the phylogeny of STEC of multiple serogroups. The dendrograms obtained identified groups of STEC segregating approximately with the serogroups and allowed the identification of subpopulations within the single groups. The study of the allelic signatures provided further evidence of the coevolution of the LEE and OI-122, reflecting the occurrence of their acquisition through a single event. The HReVAP analysis represents a sensitive tool for studying the evolution of LEE-positive STEC.

  19. Development of a High Resolution Virulence Allelic Profiling (HReVAP) Approach Based on the Accessory Genome of Escherichia coli to Characterize Shiga-Toxin Producing E. coli (STEC)

    Science.gov (United States)

    Michelacci, Valeria; Orsini, Massimiliano; Knijn, Arnold; Delannoy, Sabine; Fach, Patrick; Caprioli, Alfredo; Morabito, Stefano

    2016-01-01

    Shiga-toxin producing Escherichia coli (STEC) strains possess a large accessory genome composed of virulence genes existing in multiple allelic variants, which sometimes segregate with specific STEC subpopulations. We analyzed the allelic variability of 91 virulence genes of STEC by Real Time PCR followed by melting curves analysis in 713 E. coli strains including 358 STEC. The 91 genes investigated were located on the locus of enterocyte effacement (LEE), OI-57, and OI-122 pathogenicity islands and displayed a total of 476 alleles in the study population. The combinations of the 91 alleles of each strain were termed allelic signatures and used to perform cluster analyses. We termed such an approach High Resolution Virulence Allelic Profiling (HReVAP) and used it to investigate the phylogeny of STEC of multiple serogroups. The dendrograms obtained identified groups of STEC segregating approximately with the serogroups and allowed the identification of subpopulations within the single groups. The study of the allelic signatures provided further evidence of the coevolution of the LEE and OI-122, reflecting the occurrence of their acquisition through a single event. The HReVAP analysis represents a sensitive tool for studying the evolution of LEE-positive STEC. PMID:26941726

  20. Biodegradation of the Polyketide Toxin Cercosporin

    OpenAIRE

    Mitchell, Thomas K.; Chilton, William Scott; Daub, Margaret E.

    2002-01-01

    Cercosporin is a non-host-specific polyketide toxin produced by many species of plant pathogens belonging to the genus Cercospora. This red-pigmented, light-activated toxin is an important pathogenicity determinant for Cercospora species. In this study, we screened 244 bacterial isolates representing 12 different genera for the ability to degrade cercosporin. Cercosporin degradation was determined by screening for the presence of cleared zones surrounding colonies on cercosporin-containing cu...

  1. Updates on tetanus toxin: a fundamental approach

    Directory of Open Access Journals (Sweden)

    Md. Ahaduzzaman

    2015-03-01

    Full Text Available Clostridium tetani is an anaerobic bacterium that produces second most poisonous protein toxins than any other bacteria. Tetanus in animals is sporadic in nature but difficult to combat even by using antibiotics and antiserum. It is crucial to understand the fundamental mechanisms and signals that control toxin production for advance research and medicinal uses. This review was intended for better understanding the basic patho-physiology of tetanus and neurotoxins (TeNT among the audience of related field.

  2. Regulations for marine microalgal toxins: Towards harmonization of ...

    African Journals Online (AJOL)

    Toxins produced by marine microalgae are harmful to humans and a serious threat to aquaculture and fisheries. Most seafood-producing countries have established monitoring programmes and regulations to protect public health from the risk of toxin exposure. However, there are disparities in current regulations regarding ...

  3. Detection of shiga toxins by lateral flow assay

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli (STEC) produce Shiga toxins (Stxs) that can cause human disease and death. The contamination of food products with STEC represents a food safety problem that necessitates rapid and effective detection strategies to mitigate risk. In this manuscript we report ...

  4. Climate change and genetically modified insecticidal plants. Plant-herbivore interactions and secondary chemistry of Bt Cry1Ac-toxin producing oilseed rape (Brassica napus L.) under elevated CO{sub 2} or O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Himanen, S.

    2008-07-01

    Transgenic insect-resistant plants producing Bacillus thuringiensis (Bt) crystalline endotoxins are the first commercial applications of genetically modified crops and their use has steadily expanded over the last ten years. Together with the expanding agricultural use of transgenic crops, climate change is predicted to be among the major factors affecting agriculture in the coming years. Plants, herbivores and insects of higher trophic levels are all predicted to be affected by the current atmospheric climate change. However, only very few studies to date have addressed the sustained use and herbivore interactions of Bt-producing plants under the influence of these abiotic factors. The main objective of this study was to comparatively assess the performance of a Bt Cry1Ac toxin-producing oilseed rape line and its non-transgenic parent line in terms of vegetative growth and allocation to secondary defence compounds (glucosinolates and volatile terpenoids), and the performance of Bt-target and nontarget insect herbivores as well as tritrophic interaction functioning on these lines. For this, several growth chamber experiments with vegetative stage non-Bt and Bt plants facing exposures to doubled atmospheric CO{sub 2} level alone or together with increased temperature and different regimes of elevated O{sub 3} were conducted. The main hypothesis of this work was that Bt-transgenic plants have reduced performance or allocation to secondary compounds due to the cost of producing Bt toxin under changed abiotic environments. The Bt-transgenic oilseed rape line exhibited slightly delayed vegetative growth and had increased nitrogen and reduced carbon content compared to the non-transgenic parent line, but the physiological responses (i.e. biomass gain and photosynthesis) of the plant lines to CO{sub 2} and O{sub 3} enhancements were equal. Two aphid species, non-susceptible to Bt Cry1Ac, showed equal performance and reproduction on both plant lines under elevated CO{sub 2

  5. Clostridium perfringens delta toxin is sequence related to beta toxin, NetB, and Staphylococcus pore-forming toxins, but shows functional differences.

    Directory of Open Access Journals (Sweden)

    Maria Manich

    Full Text Available Clostridium perfringens produces numerous toxins, which are responsible for severe diseases in man and animals. Delta toxin is one of the three hemolysins released by a number of C. perfringens type C and possibly type B strains. Delta toxin was characterized to be cytotoxic for cells expressing the ganglioside G(M2 in their membrane. Here we report the genetic characterization of Delta toxin and its pore forming activity in lipid bilayers. Delta toxin consists of 318 amino acids, its 28 N-terminal amino acids corresponding to a signal peptide. The secreted Delta toxin (290 amino acids; 32619 Da is a basic protein (pI 9.1 which shows a significant homology with C. perfringens Beta toxin (43% identity, with C. perfringens NetB (40% identity and, to a lesser extent, with Staphylococcus aureus alpha toxin and leukotoxins. Recombinant Delta toxin showed a preference for binding to G(M2, in contrast to Beta toxin, which did not bind to gangliosides. It is hemolytic for sheep red blood cells and cytotoxic for HeLa cells. In artificial diphytanoyl phosphatidylcholine membranes, Delta and Beta toxin formed channels. Conductance of the channels formed by Delta toxin, with a value of about 100 pS to more than 1 nS in 1 M KCl and a membrane potential of 20 mV, was higher than those formed by Beta toxin and their distribution was broader. The results of zero-current membrane potential measurements and single channel experiments suggest that Delta toxin forms slightly anion-selective channels, whereas the Beta toxin channels showed a preference for cations under the same conditions. C. perfringens Delta toxin shows a significant sequence homolgy with C. perfringens Beta and NetB toxins, as well as with S. aureus alpha hemolysin and leukotoxins, but exhibits different channel properties in lipid bilayers. In contrast to Beta toxin, Delta toxin recognizes G(M2 as receptor and forms anion-selective channels.

  6. [Hemolysis of Scolopendra toxins].

    Science.gov (United States)

    Deng, F; Fang, H; Wang, K

    1997-01-01

    The hemolysis of toxins from alive Scolopendra subspinipes mutilans, medicinal material of Scolopendra subspimipes mutilans and S. multidens have been compared. The result shows that all the toxins have hemolytic activity. The hemolytic activity of the toxin from the medicinal materials of S. subspinipes mutilans is obviously lower than that from alive ones, and that from fresh medicinal materials are twice as high that from old ones, and that from S. multidens is higher than that from S. subspinipes multilans.

  7. Prevalence of carriage of Shiga toxin-producing Escherichia coli serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 among slaughtered adult cattle in France.

    Science.gov (United States)

    Bibbal, Delphine; Loukiadis, Estelle; Kérourédan, Monique; Ferré, Franck; Dilasser, Françoise; Peytavin de Garam, Carine; Cartier, Philippe; Oswald, Eric; Gay, Emilie; Auvray, Frédéric; Brugère, Hubert

    2015-02-01

    The main pathogenic enterohemorrhagic Escherichia coli (EHEC) strains are defined as Shiga toxin (Stx)-producing E. coli (STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (eae). The objective of this study was to evaluate the prevalence of bovine carriers of these “top five” STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows, and 394 beef cows. A total of 96 E. coli isolates, including 33 top five STEC and 63 atypical enteropathogenic E. coli (aEPEC) isolates, with the same genetic characteristics as the top five STEC strains except that they lacked an stx gene, were recovered from these samples.O157:H7 was the most frequently isolated STEC serotype. The prevalence of top five STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows, and 1.0% in beef cows. It was significantly higher in young dairy bulls (P<0.05) than in the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover,simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France.

  8. Efficacy of a Blend of Sulfuric Acid and Sodium Sulfate against Shiga Toxin-Producing Escherichia coli, Salmonella, and Nonpathogenic Escherichia coli Biotype I on Inoculated Prerigor Beef Surface Tissue.

    Science.gov (United States)

    Scott-Bullard, Britteny R; Geornaras, Ifigenia; Delmore, Robert J; Woerner, Dale R; Reagan, James O; Morgan, J Bred; Belk, Keith E

    2017-12-01

    A study was conducted to investigate the efficacy of a sulfuric acid-sodium sulfate blend (SSS) against Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli (STEC), Salmonella, and nonpathogenic E. coli biotype I on prerigor beef surface tissue. The suitability of using the nonpathogenic E. coli as a surrogate for in-plant validation studies was also determined by comparing the data obtained for the nonpathogenic inoculum with those for the pathogenic inocula. Prerigor beef tissue samples (10 by 10 cm) were inoculated (ca. 6 log CFU/cm 2 ) on the adipose side in a laboratory-scale spray cabinet with multistrain mixtures of E. coli O157:H7 (5 strains), non-O157 STEC (12 strains), Salmonella (6 strains), or E. coli biotype I (5 strains). Treatment parameters evaluated were two SSS pH values (1.5 and 1.0) and two spray application pressures (13 and 22 lb/in 2 ). Untreated inoculated beef tissue samples served as controls for initial bacterial populations. Overall, the SSS treatments lowered inoculated (6.1 to 6.4 log CFU/cm 2 ) bacterial populations by 0.6 to 1.5 log CFU/cm 2 (P coli inocula; however, solution pH did have a significant effect (P coli inoculum to the SSS treatments was similar (P ≥ 0.05) to that of the pathogenic inocula tested, making the E. coli biotype I strains viable surrogate organisms for in-plant validation of SSS efficacy on beef. The application of SSS at the tested parameters to prerigor beef surface tissue may be an effective intervention for controlling pathogens in a commercial beef harvest process.

  9. Presence of Multidrug-Resistant Shiga Toxin-Producing Escherichia coli, Enteropathogenic E. coli and Enterotoxigenic E. coli, on Raw Nopalitos (Opuntia ficus-indica L.) and in Nopalitos Salads from Local Retail Markets in Mexico.

    Science.gov (United States)

    Gómez-Aldapa, Carlos A; Cerna-Cortes, Jorge F; Rangel-Vargas, Esmeralda; Torres-Vitela, Mdel Refugio; Villarruel-López, Angelica; Gutiérrez-Alcántara, Eduardo J; Castro-Rosas, Javier

    2016-05-01

    The presence of multidrug-resistant pathogenic bacteria in food is a significant public health concern. Diarrheagenic Escherichia coli pathotypes (DEPs) are foodborne bacteria. In Mexico, DEPs have been associated with diarrheal illness. There is no information about the presence of multidrug-resistant DEPs on fresh vegetables and in cooked vegetable salads in Mexico. "Nopalitos" (Opuntia ficus-indica L.) is a Cactacea extensively used as a fresh green vegetable throughout Mexico. The presence of generic E. coli and multidrug-resistant DEPs on raw whole and cut nopalitos and in nopalitos salad samples was determined. One hundred raw whole nopalitos (without prickles) samples, 100 raw nopalitos cut into small square samples, and 100 cooked nopalitos salad samples were collected from markets. Generic E. coli was determined using the most probable number procedures. DEPs were identified using two multiplex polymerase chain reaction procedures. Susceptibility to 16 antibiotics was tested for the isolated DEP strains by standard test. Of the 100 whole nopalitos samples, 100 cut nopalitos samples, and 100 nopalitos salad samples, generic E. coli and DEPs were identified, respectively, in 80% and 10%, 74% and 10%, and 64% and 8%. Eighty-two DEP strains were isolated from positive nopalitos samples. The identified DEPs included Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). All isolated strains exhibited resistance to at least six antibiotics. To the best of our knowledge, this is the first report of the presence of multidrug-resistant and antibiotic resistance profiles of STEC, ETEC, and EPEC on raw nopalitos and in nopalitos salads in Mexico.

  10. Comparison of decontamination efficacy of antimicrobial treatments for beef trimmings against Escherichia coli O157:H7 and 6 non-O157 Shiga toxin-producing E. coli serogroups.

    Science.gov (United States)

    Geornaras, Ifigenia; Yang, Hua; Manios, Stavros; Andritsos, Nikolaos; Belk, Keith E; Nightingale, Kendra K; Woerner, Dale R; Smith, Gary C; Sofos, John N

    2012-09-01

    The decontamination efficacy of 6 chemical treatments for beef trimmings were evaluated against Escherichia coli O157:H7 and 6 non-O157 Shiga toxin-producing E. coli (nSTEC) serogroups. Rifampicin-resistant 4-strain mixtures of E. coli O157:H7 and nSTEC serogroups O26, O45, O103, O111, O121, and O145 were separately inoculated (3 to 4 log CFU/cm(2)) onto trimmings (10 × 5 × 1 cm; approximately 100 g) fabricated from beef chuck rolls, and were immersed for 30 s in solutions of acidified sodium chlorite (0.1%, pH 2.5), peroxyacetic acid (0.02%, pH 3.8), sodium metasilicate (4%, pH 12.5), Bromitize(®) Plus (0.0225% active bromine, pH 6.6), or AFTEC 3000 (pH 1.2), or for 5 s in SYNTRx 3300 (pH 1.0). Each antimicrobial was tested independently together with an untreated control. Results showed that all tested decontamination treatments were similarly effective against the 6 nSTEC serogroups as they were against E. coli O157:H7. Irrespective of pathogen inoculum, treatment of beef trimmings with acidified sodium chlorite, peroxyacetic acid, or sodium metasilicate effectively (P antimicrobial treatments to control pathogen contamination on fresh beef products; and (ii) regulatory agencies as they consider approaches for better control of the studied pathogens. © 2012 Institute of Food Technologists®

  11. Immune-stimulating properties of 80% methanolic extract of Ludwigia octovalvis against Shiga toxin-producing E. coli O157:H7 in Balb/c mice following experimental infection.

    Science.gov (United States)

    Kadum Yakob, Haidar; Manaf Uyub, Abd; Fariza Sulaiman, Shaida

    2015-08-22

    Ludwigia octovalvis is an aquatic plant widely distributed throughout the tropical and sub-tropical regions. It is commonly consumed as a health drink and traditionally used for treating various ailments such as dysentery, diarrhea, diabetes, nephritisn and headache. No information is available on its in vivo antibacterial activity against an important foodborne pathogen, Shiga toxin producing Escherichia coli O157:H7. Male Balb/c mice were orally administered with the extract at doses of 200 or 400mg/kg body weight for one week before the infection with E. coli O157:H7 and continued for 14 consecutive days after infection. Serum antibody (IgA, IgG and IgM) levels were quantified at days 7 and 14 post-challenge by an ADVIA(®) 2400 Clinical Chemistry Auto Analyzer. Nitroblue tetrazolium (NBT) and Ceruloplasmin, as nonspecific immune parameters, were determined enzymatically. A significant increase (p400mg/kg of the extract in comparison with other groups. Total IgA serum levels on day 7 post-challenge in groups of PBS negative control, E. coli O157:H7 positive control, E. coli O157:H7+200mg/kg extract group and E. coli O157:H7+400mg/kg extract group were 709.4 ± 149.6, 1655.8 ± 139.7, 1728.6 ± 64.3 and 1971.4 ± 135.6 µg/ml, respectively. Serum IgG and IgM did not significantly change among different groups. The extract administered orally to infected Balb/c mice did not affect the NBT as well as ceruloplasmin levels. The extract of L. octovalvis contains biologically active principles which increased systemic immune response to E. coli O157:H7 via potentiating the synthesis of IgA antibodies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. The Genetia, Harbored by the Subtilase-Encoding Pathogenicity Island, Is Involved in the Ability of Locus of Enterocyte Effacement-Negative Shiga Toxin-Producing Escherichia coli Strains To Invade Monolayers of Epithelial Cells.

    Science.gov (United States)

    Bondì, Roslen; Chiani, Paola; Michelacci, Valeria; Minelli, Fabio; Caprioli, Alfredo; Morabito, Stefano

    2017-12-01

    Locus of enterocyte effacement (LEE)-negative Shiga toxin (Stx)-producing Escherichia coli (STEC) strains are human pathogens that lack the LEE locus, a pathogenicity island (PAI) involved in the intimate adhesion of LEE-positive strains to the host gut epithelium. The mechanism used by LEE-negative STEC strains to colonize the host intestinal mucosa is still not clear. The cell invasion determinant tia , previously described in enterotoxigenic E. coli strains, has been identified in LEE-negative STEC strains that possess the subtilase-encoding pathogenicity island (SE-PAI). We evaluated the role of the gene tia , present in these LEE-negative STEC strains, in the invasion of monolayers of cultured cells. We observed that these strains were able to invade Caco-2 and HEp-2 cell monolayers and compared their invasion ability with that of a mutant strain in which the gene tia had been inactivated. Mutation of the gene tia resulted in a strong reduction of the invasive phenotype, and complementation of the tia mutation with a functional copy of the gene restored the invasion activity. Moreover, we show that the gene tia is overexpressed in bacteria actively invading cell monolayers, demonstrating that tia is involved in the ability to invade cultured monolayers of epithelial cells shown by SE-PAI-positive E. coli , including STEC, strains. However, the expression of the tia gene in the E. coli K-12 strain JM109 was not sufficient, in its own right, to confer to this strain the ability to invade cell monolayers, suggesting that at least another factor must be involved in the invasion ability displayed by the SE-PAI-positive strains. Copyright © 2017 American Society for Microbiology.

  13. Isolation, Characterization and Antibiotic Resistance of Shiga Toxin-Producing Escherichia coli in Hamburger and Evolution of Virulence Genes stx1, stx2, eaeA and hly by Multiplex PCR

    Directory of Open Access Journals (Sweden)

    Mohammad Kargar

    2013-09-01

    Full Text Available Background & Objectives: Shiga toxin-producing Escherichia coli (STEC O157:H7 have emerged as pathogens that can cause food-borne infections and severe and potentially fatal illnesses in humans. E.coli O157:H7 colonizes the digestive tract of cattle and is transmitted to humans by food and water. The objectives of this study were to characterize the prevalence of E.coli O157:H7 isolates in hamburger in Shiraz and to test their antimicrobial sensitivity. Material & Methods: In this research, 428 samples of hamburger were collected from 7 main factories of meat products and enriched in TSB with novobiocin medium at 37ºC. Fermentation of sorbitol and lactose and activities of β- glucuronidase of separated bacteria were examined by using the SMAC and VRBA media and CHROMagar medium. Then isolation of E.coli O157:H7 was confirmed with the use of specific antisera; and with the multiplex PCR method, the presence of E.coli O157:H7 virulence genes – including stx1, stx2, eaeA, and hly – was analyzed. Finally, antibiotic resistance strains were tested with disk diffusion methods. Results: Out of all the examined samples, 264 (61.68% sorbitol-negative bacteria were separated in the CT-SMAC medium. After evaluation with specific antisera, the rate of the recognition of E.coli O157:H7 was 5 (1.17%. The stx1 and eaeA genes were diagnosed in 2 (0.47% cases of these samples. All the isolated bacteria were resistant to penicillin, clindamycin, and erythromycin antibiotics.Conclusion: The presence of STEC in animal products suggests that they may be a potential hazard for human health. A regular monitoring of STEC O157, mainly in hamburger, should be performed to prevent a possible consumer health threat.

  14. Prevalence of Carriage of Shiga Toxin-Producing Escherichia coli Serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 among Slaughtered Adult Cattle in France

    Science.gov (United States)

    Loukiadis, Estelle; Kérourédan, Monique; Ferré, Franck; Dilasser, Françoise; Peytavin de Garam, Carine; Cartier, Philippe; Oswald, Eric; Gay, Emilie; Auvray, Frédéric; Brugère, Hubert

    2014-01-01

    The main pathogenic enterohemorrhagic Escherichia coli (EHEC) strains are defined as Shiga toxin (Stx)-producing E. coli (STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (eae). The objective of this study was to evaluate the prevalence of bovine carriers of these “top five” STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows, and 394 beef cows. A total of 96 E. coli isolates, including 33 top five STEC and 63 atypical enteropathogenic E. coli (aEPEC) isolates, with the same genetic characteristics as the top five STEC strains except that they lacked an stx gene, were recovered from these samples. O157:H7 was the most frequently isolated STEC serotype. The prevalence of top five STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows, and 1.0% in beef cows. It was significantly higher in young dairy bulls (P < 0.05) than in the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover, simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France. PMID:25527532

  15. The effect of magnesium hydroxide, hydromagnesite and layered double hydroxide on the heat stability and fire performance of plasticized poly(vinyl chloride)

    CSIR Research Space (South Africa)

    Molefe, DM

    2015-09-01

    Full Text Available Emulsion grade PVC was plasticised with 100 phr diisononyl phthalate and filled with 30 phr of different hydrated filler-type flame retardant additives. Static heat stabilities were determined at 200 oC by following the time dependance of hydrogen...

  16. Neutralising Antibodies against Ricin Toxin

    Science.gov (United States)

    Prigent, Julie; Panigai, Laetitia; Lamourette, Patricia; Sauvaire, Didier; Devilliers, Karine; Plaisance, Marc; Volland, Hervé; Créminon, Christophe; Simon, Stéphanie

    2011-01-01

    The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC50 of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg) protected mice from intranasal challenges with ricin (5 LD50). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention. PMID:21633505

  17. Neutralising antibodies against ricin toxin.

    Directory of Open Access Journals (Sweden)

    Julie Prigent

    Full Text Available The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs were produced against the two chains of ricin toxin (RTA and RTB. Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37 and one anti-RTA (RA36, when used in combination improved neutralising capacity in vitro with an IC(50 of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg protected mice from intranasal challenges with ricin (5 LD(50. Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention.

  18. Supercritical CO2 interpolymer complex encapsulation improves heat stability of probiotic bifidobacteria.

    Science.gov (United States)

    Thantsha, M S; Labuschagne, P W; Mamvura, C I

    2014-02-01

    The probiotic industry faces the challenge of retention of probiotic culture viability as numbers of these cells within their products inevitably decrease over time. In order to retain probiotic viability levels above the therapeutic minimum over the duration of the product's shelf life, various methods have been employed, among which encapsulation has received much interest. In line with exploitation of encapsulation for protection of probiotics against adverse conditions, we have previously encapsulated bifidobacteria in poly-(vinylpyrrolidone)-poly-(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex microparticles under supercritical conditions. The microparticles produced had suitable characteristics for food applications and also protected the bacteria in simulated gastrointestinal fluids. The current study reports on accelerated shelf life studies of PVP:PVAc-CA encapsulated Bifidobacterium lactis Bb12 and Bifidobacterium longum Bb46. Samples were stored as free powders in glass vials at 30 °C for 12 weeks and then analysed for viable counts and water activity levels weekly or fortnightly. Water activities of the samples were within the range of 0.25-0.43, with an average a(w) = 0.34, throughout the storage period. PVP:PVAc-CA interpolymer complex encapsulation retained viable levels above the recommended minimum for 10 and 12 weeks, for B. longum Bb46 and B. lactis Bb12, respectively, thereby extending their shelf lives under high storage temperature by between 4 and 7 weeks. These results reveal the possibility for manufacture of encapsulated probiotic powders with increased stability at ambient temperatures. This would potentially allow the supply of a stable probiotic formulation to impoverished communities without proper storage facilities recommended for most of the currently available commercial probiotic products.

  19. Evaluation of a multiplex real-time PCR method for detecting shiga toxin-producing Escherichia coli in beef and comparison to the U.S. Department of Agriculture Food Safety and Inspection Service Microbiology laboratory guidebook method.

    Science.gov (United States)

    Fratamico, Pina M; Wasilenko, Jamie L; Garman, Bradley; Demarco, Daniel R; Varkey, Stephen; Jensen, Mark; Rhoden, Kyle; Tice, George

    2014-02-01

    The "top-six" non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) most frequently associated with outbreaks and cases of foodborne illnesses have been declared as adulterants in beef by the U.S. Department of Agriculture Food Safety and Inspection Service (FSIS). Regulatory testing in beef began in June 2012. The purpose of this study was to evaluate the DuPont BAX System method for detecting these top six STEC strains and strains of E. coli O157:H7. For STEC, the BAX System real-time STEC suite was evaluated, including a screening assay for the stx and eae virulence genes and two panel assays to identify the target serogroups: panel 1 detects O26, O111, and O121, and panel 2 detects O45, O103, O145. For E. coli O157:H7, the BAX System real-time PCR assay for this specific serotype was used. Sensitivity of each assay for the PCR targets was ≥1.23 × 10(3) CFU/ml in pure culture. Each assay was 100% inclusive for the strains tested (20 to 50 per assay), and no cross-reactivity with closely related strains was observed in any of the assays. The performance of the BAX System methods was compared with that of the FSIS Microbiology Laboratory Guidebook (MLG) methods for detection of the top six STEC and E. coli O157:H7 strains in ground beef and beef trim. Generally, results of the BAX System method were similar to those of the MLG methods for detecting non-O157 STEC and E. coli O157:H7. Reducing or eliminating novobiocin in modified tryptic soy broth (mTSB) may improve the detection of STEC O111 strains; one beef trim sample inoculated with STEC O111 produced a negative result when enriched in mTSB with 8 mg/liter novobiocin but was positive when enriched in mTSB without novobiocin. The results of this study indicate the feasibility of deploying a panel of real-time PCR assay configurations for the detection and monitoring of the top six STEC and E. coli O157:H7 strains in beef. The approach could easily be adapted

  20. Phage Types and Genotypes of Shiga Toxin-Producing Escherichia coli O157:H7 Isolates from Humans and Animals in Spain: Identification and Characterization of Two Predominating Phage Types (PT2 and PT8)

    Science.gov (United States)

    Mora, Azucena; Blanco, Miguel; Blanco, Jesús E.; Alonso, M. Pilar; Dhabi, Ghizlane; Thomson-Carter, Fiona; Usera, Miguel A.; Bartolomé, Rosa; Prats, Guillermo; Blanco, Jorge

    2004-01-01

    Phage typing and DNA macrorestriction fragment analysis by pulsed-field electrophoresis (PFGE) were used for the epidemiological subtyping of a collection of Shiga toxin-producing Escherichia coli (STEC) O157:H7 strains isolated in Spain between 1980 and 1999. Phage typing distinguished a total of 18 phage types among 171 strains isolated from different sources (67 humans, 82 bovines, 12 ovines, and 10 beef products). However, five phage types, phage type 2 (PT2; 42 strains), PT8 (33 strains), PT14 (14 strains), PT21/28 (11 strains), and PT54 (16 strains), accounted for 68% of the study isolates. PT2 and PT8 were the most frequently found among strains from both humans (51%) and bovines (46%). Interestingly, we detected a significant association between PT2 and PT14 and the presence of acute pathologies. A group of 108 of the 171 strains were analyzed by PFGE, and 53 distinct XbaI macrorestriction patterns were identified, with 38 strains exhibiting unique PFGE patterns. In contrast, phage typing identified 15 different phage types. A total of 66 phage type-PFGE subtype combinations were identified among the 108 strains. PFGE subtyping differentiated between unrelated strains that exhibited the same phage type. The most common phage type-PFGE pattern combinations were PT2-PFGE type 1 (1 human and 11 bovine strains), PT8-PFGE type 8 (2 human, 6 bovine, and 1 beef product strains), PT2-PFGE subtype 4A (1 human, 3 bovine, and 1 beef product strains). Nine (29%) of 31 human strains showed phage type-PFGE pattern combinations that were detected among the bovine strains included in this study, and 26 (38%) of 68 bovine strains produced phage type-PFGE pattern combinations observed among human strains included in this study, confirming that cattle are a major reservoir of strains pathogenic for humans. PT2 and PT8 strains formed two groups which differed from each other in their motilities, stx genotypes, PFGE patterns, and the severity of the illnesses that they caused

  1. Pilot Dietary Intervention with Heat-Stabilized Rice Bran Modulates Stool Microbiota and Metabolites in Healthy Adults

    Directory of Open Access Journals (Sweden)

    Amy M. Sheflin

    2015-02-01

    Full Text Available Heat-stabilized rice bran (SRB has been shown to regulate blood lipids and glucose, modulate gut mucosal immunity and inhibit colorectal cancer in animal and human studies. However, SRB’s effects on gut microbial composition and metabolism and the resulting implications for health remain largely unknown. A pilot, randomized-controlled trial was developed to investigate the effects of eating 30 g/day SRB on the stool microbiome and metabolome. Seven healthy participants consumed a study meal and snack daily for 28 days. The microbiome and metabolome were characterized using 454 pyrosequencing and gas chromatography-mass spectrometry (GC-MS at baseline, two and four weeks post-intervention. Increases in eight operational taxonomic units (OTUs, including three from Bifidobacterium and Ruminococcus genera, were observed after two and four weeks of SRB consumption (p < 0.01. Branched chain fatty acids, secondary bile acids and eleven other putative microbial metabolites were significantly elevated in the SRB group after four weeks. The largest metabolite change was a rice bran component, indole-2-carboxylic acid, which showed a mean 12% increase with SRB consumption. These data support the feasibility of dietary SRB intervention in adults and support that SRB consumption can affect gut microbial metabolism. These findings warrant future investigations of larger cohorts evaluating SRB’s effects on intestinal health.

  2. Protection against Shiga Toxins

    Directory of Open Access Journals (Sweden)

    Simona Kavaliauskiene

    2017-02-01

    Full Text Available Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3 on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to the endoplasmic reticulum. The enzymatically active part of the A-moiety is then translocated to the cytosol, where it inhibits protein synthesis and in some cell types induces apoptosis. Protection of cells can be provided either by inhibiting binding of the toxin to cells or by interfering with any of the subsequent steps required for its toxic effect. In this article we provide a brief overview of the interaction of Shiga toxins with cells, describe some compounds and conditions found to protect cells against Shiga toxins, and discuss whether they might also provide protection in animals and humans.

  3. Cytoskeleton as an Emerging Target of Anthrax Toxins

    Science.gov (United States)

    Trescos, Yannick; Tournier, Jean-Nicolas

    2012-01-01

    Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT) and edema toxin (ET). So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity. PMID:22474568

  4. Cytoskeleton as an Emerging Target of Anthrax Toxins

    Directory of Open Access Journals (Sweden)

    Jean-Nicolas Tournier

    2012-02-01

    Full Text Available Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT and edema toxin (ET. So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity.

  5. [Toxins of Clostridium perfringens as a natural and bioterroristic threats].

    Science.gov (United States)

    Omernik, Andrzej; Płusa, Tadeusz

    2015-09-01

    Clostridium perfringens is absolutely anaerobic rod-shaped, sporeforming bacterium. The morbidity is connected with producing toxins. Depending on the type of toxin produced Clostridium perfringens can be divided into five serotypes:A-E. Under natural conditions, this bacterium is responsible for local outbreaks of food poisoning associated with eating contaminated food which which was improperly heat treated. Some countries with lower economic level are endemic foci of necrotizing enteritis caused by Clostridium perfringens. The bacterium is also a major cause of gas gangrene. It is a disease, associated with wound infection, with potentially fatal prognosis in the case of treatment's delays. In the absence of early radical surgery, antibiotic therapy and (if available) hyperbaric treatment leads to the spread of toxins in the body causing shock, coma and death. Due to the force of produced toxins is a pathogen that poses a substrate for the production of biological weapons. It could potentially be used to induce outbreaks of food poisoning and by missiles contamination by spore lead to increased morbidity of gas gangrene in injured soldiers. C. perfringens types B and D produce epsilon toxin considered to be the third most powerful bacterial toxin. Because of the ability to disperse the toxin as an aerosol and a lack of methods of treatment and prevention of poisoning possible factors it is a potential tool for bioterrorism It is advisable to continue research into vaccines and treatments for poisoning toxins of C. perfringens. © 2015 MEDPRESS.

  6. 42 CFR 73.3 - HHS select agents and toxins.

    Science.gov (United States)

    2010-10-01

    ..., and Recombinant Organisms: (1) Nucleic acids that can produce infectious forms of any of the select... naturally occurring environment provided the select agent or toxin has not been intentionally introduced... against theft, loss, or release, and reports any theft, loss, or release of such agent or toxin, and (3...

  7. Toxicological Perspective on Climate Change: Aquatic Toxins.

    Science.gov (United States)

    Botana, Luis M

    2016-04-18

    In recent years, our group and several others have been describing the presence of new, not previously reported, toxins of high toxicity in vectors that may reach the human food chain. These include tetrodotoxin in gastropods in the South of Europe, ciguatoxin in fish in the South of Spain, palytoxin in mussels in the Mediterranean Sea, pinnatoxin all over Europe, and okadaic acid in the south of the U.S. There seem to be new marine toxins appearing in areas that are heavy producers of seafood, and this is a cause of concern as most of these new toxins are not included in current legislation and monitoring programs. Along with the new toxins, new chemical analogues are being reported. The same phenomenom is being recorded in freshwater toxins, such as the wide appearance of cylindrospermopsin and the large worldwide increase of microcystin. The problem that this phenomenon, which may be linked to climate warming, poses for toxicologists is very important not only because there is a lack of chronic studies and an incomplete comprehension of the mechanism driving the production of these toxins but also because the lack of a legal framework for them allows many of these toxins to reach the market. In some cases, it is very difficult to control these toxins because there are not enough standards available, they are not always certified, and there is an insufficient understanding of the toxic equivalency factors of the different analogues in each group. All of these factors have been revealed and grouped through the massive increase in the use of LC-MS as a monitoring tool, legally demanded, creating more toxicological problems.

  8. Detection and Isolation of the "Top Seven" Shiga Toxin-Producing Escherichia coli in Ground Beef: Comparison of RapidFinder Kits to the U.S. Department of Agriculture Microbiology Laboratory Guidebook Method.

    Science.gov (United States)

    Fratamico, Pina M; Bagi, Lori K; Abdul-Wakeel, Aisha

    2017-04-12

    Shiga toxin-producing Escherichia coli (STEC) O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 are often referred to as the "top seven" STEC, and these have been declared to be adulterants in beef by the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS). The aim of this work was to compare the methods described in the USDA FSIS Microbiology Laboratory Guidebook (MLG) to a two-stage Applied Biosystems RapidFinder STEC real-time PCR method to test for the top seven STEC in raw ground beef. The specificity of the RapidFinder workflow that targets non-O157 STEC O-antigen genes, stx 1 , stx 2 , and eae, and E. coli O157-specific targets was determined with 132 top seven STEC strains and 283 exclusion strains. All inclusion strains were positive, and all exclusion strains gave negative results with the RapidFinder assay. Strains carrying all of the known variants of stx 1 and stx 2 , including stx 2f and stx 2g , were also detected. For RapidFinder analysis, 375-g ground beef samples spiked with ≥4 CFU of representative STEC strains were enriched in 1 L of tryptic soy broth (TSB) for 10 h at 42 ± 1°C, and for the MLG method, 325-g samples were similarly spiked and enriched in 975 mL of modified TSB for 15 h at 42 ± 1°C. Following DNA extraction, real-time PCR was performed using RapidFinder Express software, and for the MLG method, the BAX Real-Time PCR STEC Suite and the BAX Real-Time E. coli O157:H7 assay were used with the BAX System Q7 software. Following immunomagnetic separation, presumptive colonies from modified Rainbow agar O157 plates were confirmed by the real-time PCR assays. Results of the RapidFinder and BAX assays were similar; all samples were positive after 10 and 15 h of enrichment, respectively. Isolation and confirmation of isolates was possible on all samples, except that two O111:NM strains could not be isolated from a portion of the inoculated samples. Thus, the RapidFinder system can be used for

  9. An interlaboratory study on efficient detection of Shiga toxin-producing Escherichia coli O26, O103, O111, O121, O145, and O157 in food using real-time PCR assay and chromogenic agar.

    Science.gov (United States)

    Hara-Kudo, Yukiko; Konishi, Noriko; Ohtsuka, Kayoko; Iwabuchi, Kaori; Kikuchi, Rie; Isobe, Junko; Yamazaki, Takumiko; Suzuki, Fumie; Nagai, Yuhki; Yamada, Hiroko; Tanouchi, Atsuko; Mori, Tetsuya; Nakagawa, Hiroshi; Ueda, Yasufumi; Terajima, Jun

    2016-08-02

    To establish an efficient detection method for Shiga toxin (Stx)-producing Escherichia coli (STEC) O26, O103, O111, O121, O145, and O157 in food, an interlaboratory study using all the serogroups of detection targets was firstly conducted. We employed a series of tests including enrichment, real-time PCR assays, and concentration by immunomagnetic separation, followed by plating onto selective agar media (IMS-plating methods). This study was particularly focused on the efficiencies of real-time PCR assays in detecting stx and O-antigen genes of the six serogroups and of IMS-plating methods onto selective agar media including chromogenic agar. Ground beef and radish sprouts samples were inoculated with the six STEC serogroups either at 4-6CFU/25g (low levels) or at 22-29CFU/25g (high levels). The sensitivity of stx detection in ground beef at both levels of inoculation with all six STEC serogroups was 100%. The sensitivity of stx detection was also 100% in radish sprouts at high levels of inoculation with all six STEC serogroups, and 66.7%-91.7% at low levels of inoculation. The sensitivity of detection of O-antigen genes was 100% in both ground beef and radish sprouts at high inoculation levels, while at low inoculation levels, it was 95.8%-100% in ground beef and 66.7%-91.7% in radish sprouts. The sensitivity of detection with IMS-plating was either the same or lower than those of the real-time PCR assays targeting stx and O-antigen genes. The relationship between the results of IMS-plating methods and Ct values of real-time PCR assays were firstly analyzed in detail. Ct values in most samples that tested negative in the IMS-plating method were higher than the maximum Ct values in samples that tested positive in the IMS-plating method. This study indicates that all six STEC serogroups in food contaminated with more than 29CFU/25g were detected by real-time PCR assays targeting stx and O-antigen genes and IMS-plating onto selective agar media. Therefore, screening

  10. VIABILIDADE DE Escherichia coli PRODUTORA DE TOXINA SHIGA (STEC NÃO-O157 EM QUEIJO TIPO MINAS FRESCAL. VIABILITY OF NON-O157 SHIGA TOXIN-PRODUCING Escherichia coli (STEC IN MINAS FRESCAL CHEESE

    Directory of Open Access Journals (Sweden)

    Tammy Priscila Chioda

    2009-07-01

    Full Text Available Escherichia coli, produtora de toxina Shiga (STEC, um patógeno emergente capaz de causar diarreia, colite hemorrágica e síndrome hemolítica urêmica em humanos, representa um grave problema de saúde pública em todo o mundo. O principal reservatório de STEC são os bovinos. STEC são transmitidas aos humanos, principalmente através de alimentos contaminados, destacando-se aqueles de origem bovina como carne, leite e seus derivados. O objetivo deste trabalho foi avaliar a viabilidade de STEC não-O157 em queijo minas frescal preparado com leite artificialmente contaminado com diferentes cepas dessas bactérias. Os queijos foram mantidos a 4°C e analisados no 1º, 2º, 4º, 6º e 10º dias de estocagem. As cepas de STEC mantiveram-se viáveis em 100% (32/32 dos queijos mantidos sob refrigeração por até dez dias. Os resultados mostram que o queijo minas pode ser veículo de transmissão de STEC. Recomenda-se a adoção de métodos higiênicos e sanitários desde a ordenha até o processo de produção do queijo para reduzir a possibilidade de contaminação com STEC.

    PALAVRAS-CHAVES: PCR, queijo minas, segurança alimentar, STEC.

    Shiga toxin-producing Escherichia coli (STEC an emergent foodborne pathogen that cause diarrhea, hemorrhagic colitis and haemolytic uremic syndrome in humans, represents a public health problem all over the world. Cattle are the main source of STEC. STEC are transmitted to humans by contaminated food, mainly those of bovine origin as meat and dairy products. This study aimed evaluates the non-O157 STEC viability of artificially inoculated in the milk used for the Minas Frescal cheese’s production. The cheese was kept at 4°C and analyzed at 1st, 2nd, 4th, 6th and 10th days after its production. 100% (32/32 of the cheese storad under refrigeration during 10 days had been the STEC strains viable. These results show that minas frescal cheese can transmit STEC. The adoption of good

  11. A hemolytic-uremic syndrome-associated strain O113:H21 Shiga toxin-producing Escherichia coli specifically expresses a transcriptional module containing dicA and is related to gene network dysregulation in Caco-2 cells.

    Science.gov (United States)

    Bando, Silvia Yumi; Iamashita, Priscila; Guth, Beatriz E; Dos Santos, Luis F; Fujita, André; Abe, Cecilia M; Ferreira, Leandro R; Moreira-Filho, Carlos Alberto

    2017-01-01

    Shiga toxin-producing (Stx) Escherichia coli (STEC) O113:H21 strains are associated with human diarrhea and some of these strains may cause hemolytic uremic syndrome (HUS). The molecular mechanism underlying this capacity and the differential host cell response to HUS-causing strains are not yet completely understood. In Brazil O113:H21 strains are commonly found in cattle but, so far, were not isolated from HUS patients. Here we conducted comparative gene co-expression network (GCN) analyses of two O113:H21 STEC strains: EH41, reference strain, isolated from HUS patient in Australia, and Ec472/01, isolated from cattle feces in Brazil. These strains were cultured in fresh or in Caco-2 cell conditioned media. GCN analyses were also accomplished for cultured Caco-2 cells exposed to EH41 or Ec472/01. Differential transcriptome profiles for EH41 and Ec472/01 were not significantly changed by exposure to fresh or Caco-2 conditioned media. Conversely, global gene expression comparison of both strains cultured in conditioned medium revealed a gene set exclusively expressed in EH41, which includes the dicA putative virulence factor regulator. Network analysis showed that this set of genes constitutes an EH41 specific transcriptional module. PCR analysis in Ec472/01 and in other 10 Brazilian cattle-isolated STEC strains revealed absence of dicA in all these strains. The GCNs of Caco-2 cells exposed to EH41 or to Ec472/01 presented a major transcriptional module containing many hubs related to inflammatory response that was not found in the GCN of control cells. Moreover, EH41 seems to cause gene network dysregulation in Caco-2 as evidenced by the large number of genes with high positive and negative covariance interactions. EH41 grows slowly than Ec472/01 when cultured in Caco-2 conditioned medium and fitness-related genes are hypoexpressed in that strain. Therefore, EH41 virulence may be derived from its capacity for dysregulating enterocyte genome functioning and its

  12. Toxins of molds from decaying tomato fruit.

    Science.gov (United States)

    Harwig, J; Scott, P M; Stoltz, D R; Blanchfield, B J

    1979-01-01

    Among 27 mold isolates from decaying tomatoes, culture filtrates or ethyl acetate extracts of 8 isolates grown in yeast extract-sucrose medium were markedly toxic (mortality, greater than 50%) to brine shrimp larvae. The toxicity of six of these isolates could be attributed to the presence of citrinin, tenuazonic acid, or T-2 toxin. Ethyl acetate extracts of five Alternaria isolates and one Fusarium isolate were mutagenic for Salmonella typhimurium strains. In ripe tomatoes inoculated with toxin-producing isolates and incubated at 25 degrees C, one Alternaria alternata isolate produced tenuazonic acid in seven of seven tomatoes at levels of up to 106 micrograms/g and alternariol methyl ether in one of the seven tomatoes at 0.8 microgram/g. Another A. alternata isolate produced tenuazonic acid or alternariol methyl ether at much lower levels in only three of seven tomatoes. Patulin and citrinin were produced by a Penicillium expansum isolate at levels of up to 8.4 and 0.76 microgram/g, respectively. In tomatoes incubated at 15 degrees C, a Fusarium sulphureum isolate produced T-2 toxin, HT-2 toxin, and neosolaniol at levels of up to 37.5, 37.8 and 5.6 micrograms/g, respectively. If these mycotoxins are thermostable, they may occur at detectable levels in tomato products whenever partially moldy tomatoes are used as raw material. PMID:391152

  13. Botulinum Toxin Therapy

    Science.gov (United States)

    ... AADA Health System Reform Principles Drug pricing and availability CVS dermatologic formulary restrictions Access to compounded medications ... Botulinum toxin therapy: Overview Also called botulinum rejuvenation Brand names: Botox® Cosmetic, Dysport®, MYOBLOC®, and XEOMIN® When ...

  14. Wallpaper May Breed Toxins

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_166850.html Wallpaper May Breed Toxins: Study Fungus on the walls might ... 2017 FRIDAY, June 23, 2017 (HealthDay News) -- Wallpaper may contribute to "sick building syndrome," a new study ...

  15. The ether lipid precursor hexadecylglycerol protects against Shiga toxins.

    Science.gov (United States)

    Bergan, Jonas; Skotland, Tore; Lingelem, Anne Berit Dyve; Simm, Roger; Spilsberg, Bjørn; Lindbäck, Toril; Sylvänne, Tuulia; Simolin, Helena; Ekroos, Kim; Sandvig, Kirsten

    2014-11-01

    Shiga toxin-producing Escherichia coli bacteria cause hemorrhagic colitis and hemolytic uremic syndrome in humans. Currently, only supportive treatment is available for diagnosed patients. We show here that 24-h pretreatment with an ether lipid precursor, the alkylglycerol sn-1-O-hexadecylglycerol (HG), protects HEp-2 cells against Shiga toxin and Shiga toxin 2. Also the endothelial cell lines HMEC-1 and HBMEC are protected against Shiga toxins after HG pretreatment. In contrast, the corresponding acylglycerol, DL-α-palmitin, has no effect on Shiga toxicity. Although HG treatment provides a strong protection (~30 times higher IC₅₀) against Shiga toxin, only a moderate reduction in toxin binding was observed, suggesting that retrograde transport of the toxin from the plasma membrane to the cytosol is perturbed. Furthermore, endocytosis of Shiga toxin and retrograde sorting from endosomes to the Golgi apparatus remain intact, but transport from the Golgi to the endoplasmic reticulum is inhibited by HG treatment. As previously described, HG reduces the total level of all quantified glycosphingolipids to 50-70% of control, including the Shiga toxin receptor globotriaosylceramide (Gb3), in HEp-2 cells. In accordance with this, we find that interfering with Gb3 biosynthesis by siRNA-mediated knockdown of Gb3 synthase for 24 h causes a similar cytotoxic protection and only a moderate reduction in toxin binding (to 70% of control cells). Alkylglycerols, including HG, have been administered to humans for investigation of therapeutic roles in disorders where ether lipid biosynthesis is deficient, as well as in cancer therapy. Further studies may reveal if HG can also have a therapeutic potential in Shiga toxin-producing E. coli infections.

  16. Regulation of Toxin Production in Clostridium perfringens.

    Science.gov (United States)

    Ohtani, Kaori; Shimizu, Tohru

    2016-07-05

    The Gram-positive anaerobic bacterium Clostridium perfringens is widely distributed in nature, especially in soil and the gastrointestinal tracts of humans and animals. C. perfringens causes gas gangrene and food poisoning, and it produces extracellular enzymes and toxins that are thought to act synergistically and contribute to its pathogenesis. A complicated regulatory network of toxin genes has been reported that includes a two-component system for regulatory RNA and cell-cell communication. It is necessary to clarify the global regulatory system of these genes in order to understand and treat the virulence of C. perfringens. We summarize the existing knowledge about the regulatory mechanisms here.

  17. Regulation of Toxin Production in Clostridium perfringens

    Directory of Open Access Journals (Sweden)

    Kaori Ohtani

    2016-07-01

    Full Text Available The Gram-positive anaerobic bacterium Clostridium perfringens is widely distributed in nature, especially in soil and the gastrointestinal tracts of humans and animals. C. perfringens causes gas gangrene and food poisoning, and it produces extracellular enzymes and toxins that are thought to act synergistically and contribute to its pathogenesis. A complicated regulatory network of toxin genes has been reported that includes a two-component system for regulatory RNA and cell-cell communication. It is necessary to clarify the global regulatory system of these genes in order to understand and treat the virulence of C. perfringens. We summarize the existing knowledge about the regulatory mechanisms here.

  18. Streptococcal toxins: role in pathogenesis and disease.

    Science.gov (United States)

    Barnett, Timothy C; Cole, Jason N; Rivera-Hernandez, Tania; Henningham, Anna; Paton, James C; Nizet, Victor; Walker, Mark J

    2015-12-01

    Group A Streptococcus (Streptococcus pyogenes), group B Streptococcus (Streptococcus agalactiae) and Streptococcus pneumoniae (pneumococcus) are host-adapted bacterial pathogens among the leading infectious causes of human morbidity and mortality. These microbes and related members of the genus Streptococcus produce an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire includes haemolysins, proteases, superantigens and other agents that ultimately enhance colonization and survival within the host and promote dissemination of the pathogen. © 2015 John Wiley & Sons Ltd.

  19. Regulation of Toxin Production in Clostridium perfringens

    Science.gov (United States)

    Ohtani, Kaori; Shimizu, Tohru

    2016-01-01

    The Gram-positive anaerobic bacterium Clostridium perfringens is widely distributed in nature, especially in soil and the gastrointestinal tracts of humans and animals. C. perfringens causes gas gangrene and food poisoning, and it produces extracellular enzymes and toxins that are thought to act synergistically and contribute to its pathogenesis. A complicated regulatory network of toxin genes has been reported that includes a two-component system for regulatory RNA and cell-cell communication. It is necessary to clarify the global regulatory system of these genes in order to understand and treat the virulence of C. perfringens. We summarize the existing knowledge about the regulatory mechanisms here. PMID:27399773

  20. A longevity assurance gene homolog of tomato mediates resistance to Alternaria alternata f. sp. lycopersici toxins and fumonisin B1

    NARCIS (Netherlands)

    Brandwagt, Bas F.; Mesbah, Laurent A.; Takken, Frank L.W.; Laurent, Pascal L.; Kneppers, Tarcies J.A.; Hille, Jacques; Nijkamp, H. John J.

    2000-01-01

    The phytopathogenic fungus Alternaria alternata f. sp. lycopersici (AAL) produces toxins that are essential for pathogenicity of the fungus on tomato (Lycopersicon esculentum). AAL toxins and fumonisins of the unrelated fungus Fusarium moniliforme are sphinganine-analog mycotoxins (SAMs), which

  1. Detection of Shiga Toxins by Lateral Flow Assay

    OpenAIRE

    Ching, Kathryn H.; He, Xiaohua; Stanker, Larry H.; Lin, Alice V.; McGarvey, Jeffery A.; Hnasko, Robert

    2015-01-01

    Shiga toxin-producing Escherichia coli (STEC) produce shiga toxins (Stxs) that can cause human disease and death. The contamination of food products with STEC represents a food safety problem that necessitates rapid and effective detection strategies to mitigate risk. In this manuscript, we report the development of a colorimetric lateral flow assay (LFA) for the rapid detection of Stxs in <10 min using a pair of monoclonal antibodies that bind epitopes common to Stx1 and six Stx2 variants...

  2. Occurrence of a unique protein toxin from the Indian King Cobra (Ophiophagus hannah) venom.

    Science.gov (United States)

    Gomes, A; De, P; Dasgupta, S C

    2001-01-01

    A unique (lethal-cardiotoxic-hemorrhagic) protein toxin (Toxin CM55) was isolated and purified from Indian King Cobra (Ophiophagus hannah) venom by CM-sephadex ion exchange chromatography and reverse phase HPLC. The purified toxin had an SDS-molecular weight of 22 +/- 0.5 kD. UV absorption spectra of Toxin CM55 showed a peak at 280 nm, whereas when excited at 280 nm fluorescence, Toxin CM55 showed an E(max) at 333.4 nm. Toxin CM55 had an LD(50) of 28.28 microg/20 g (i. v.) in albino mice. The cardiotoxic action of the toxin was established on isolated guinea pig/rabbit heart and guinea pig auricle. In rats, Toxin CM55 caused ECG abnormalities including widened QRS complex and monomorphic ventricular tachycardia suggesting that the possible site of action of Toxin CM55 was the ventricle. Toxin CM55 produced significant vasoconstriction on peripheral blood vessels. It produced significant contraction of isolated guinea pig ileum, rat fundus and rat uterus, which was completely antagonised by methysergide. The toxin was found to release a significant amount of serotonin from rabbit platelets. Toxin CM55 produced cutaneous hemorrhage in albino mice, which was also produced in reserpine and p-chloro phenylalanine pretreated animals. Rabbit antiserum was raised against Toxin CM55, which gave prominent bands in immunogel diffusion and immunoelectrophoresis. The antiserum provided 2 LD(50) protection against Toxin CM55-induced lethality in mice and also neutralised 3 MHD hemorrhagic dose of the toxin.

  3. Translational errors in expression of Shiga toxin from pathogenic Escherichia coli as measured by MALDI-TOF-TOF and Orbitrap mass spectrometry

    Science.gov (United States)

    Introduction: Shiga toxin (Stx) is an AB5 toxin expressed by Shiga toxin-producing E. coli (STEC) and Shigella dysenteriae. The Stx holotoxin attaches to surface receptors of eukaryotic cells. After cellular envelopment, the toxin disrupts ribosomal protein synthesis causing cell death. Variations i...

  4. Effects and mechanisms of Bacillus thuringiensis crystal toxins for mosquito larvae.

    Science.gov (United States)

    Zhang, Qi; Hua, Gang; Adang, Michael J

    2017-10-01

    Bacillus thuringiensis is a Gram-positive aerobic bacterium that produces insecticidal crystalline inclusions during sporulation phases of the mother cell. The virulence factor, known as parasporal crystals, is composed of Cry and Cyt toxins. Most Cry toxins display a common 3-domain topology. Cry toxins exert intoxication through toxin activation, receptor binding and pore formation in a suitable larval gut environment. The mosquitocidal toxins of Bt subsp. israelensis (Bti) were found to be highly active against mosquito larvae and are widely used for vector control. Bt subsp. jegathesan is another strain which possesses high potency against broad range of mosquito larvae. The present review summarizes characterized receptors for Cry toxins in mosquito larvae, and will also discuss the diversity and effects of 3-D mosquitocidal Cry toxin and the ongoing research for Cry toxin mechanisms generated from investigations of lepidopteran and dipteran larvae. © 2016 Institute of Zoology, Chinese Academy of Sciences.

  5. Botulinum Toxin (Botox) for Facial Wrinkles

    Science.gov (United States)

    ... Eye Health / Eye Health A-Z Botulinum Toxin (Botox) for Facial Wrinkles Sections Botulinum Toxin (Botox) for ... How Does Botulinum Toxin (Botox) Work? Botulinum Toxin (Botox) for Facial Wrinkles Leer en Español: La toxina ...

  6. Novel Structure and Function of Typhoid Toxin

    Science.gov (United States)

    ... Matters NIH Research Matters July 29, 2013 Novel Structure and Function of Typhoid Toxin Structure of typhoid toxin, showing the 2 A subunits ( ... to cultured cells. The scientists next determined the structure of the typhoid toxin. The toxin was already ...

  7. Milling technological experiments to reduce Fusarium toxin contamination in wheat

    Directory of Open Access Journals (Sweden)

    Véha A.

    2015-01-01

    Full Text Available We examine 4 different DON-toxin-containing (0.74 - 1.15 - 1.19 - 2.14 mg/kg winter wheat samples: they were debranned and undebranned, and we investigated the flour’s and the by-products’ (coarse, fine bran toxin content changes. SATAKE lab-debranner was used for debranning and BRABENDER lab-mill for the milling process. Without debranning, two sample flours were above the DON toxin limit (0.75 mg/kg, which are waste. By minimum debranning (and minimum debranning mass loss; 6-8%, our experience with whole flour is that the multi-stage debranning measurement significantly reduces the content of the flour’s DON toxin, while the milling by-products, only after careful consideration and DON toxin measurements, may be produced for public consumption and for feeding.

  8. Reactions with Antisera and Pathological Effects of Staphylococcus aureus Gamma-Toxin in the Cornea.

    Science.gov (United States)

    Bierdeman, Michael A; Torres, Angela M; Caballero, Armando R; Tang, Aihua; O'Callaghan, Richard J

    2017-08-01

    This study analyzed the toxicity of purified gamma-toxin from Staphylococcus aureus and the protectiveness of antisera to gamma-toxin in the rabbit cornea. Gamma-toxin was purified from cultures of alpha-toxin deficient S. aureus strain Newman Δhla. Antisera to native gamma-toxin (Hlg) were produced in rabbits. These antisera and a commercial polyclonal antibody to recombinant HlgB (rHlgB) were analyzed for specificity and toxin neutralization. Heat-inactivated gamma-toxin, active gamma-toxin either alone or with antisera or with commercial antibody to rHlgB, was injected into the rabbit cornea to observe the pathological effects using slit lamp examination scoring (SLE) and histological analyses. Eyes with intrastromal injection of gamma-toxin developed SLE scores that were significantly higher than eyes injected with heat-inactivated gamma-toxin (p ≤ 0.003). Slit lamp and histological examination of eyes revealed that gamma-toxin injected into the cornea mediated conjunctival injection and chemosis, iritis, fibrin accumulation in the anterior chamber, and polymorphonuclear neutrophil infiltration of the cornea and iris. Also, eyes injected with gamma-toxin plus antisera to native whole gamma-toxin or HlgB, but not with commercial antibody to rHlgB, yielded significantly lower SLE scores than eyes injected with gamma-toxin alone (p ≤ 0.003). This study illustrates that S. aureus gamma-toxin is capable of causing significant corneal pathology. Furthermore, the use of polyclonal antisera specific for native gamma-toxin was found to inhibit the damaging effects of the toxin in the rabbit cornea.

  9. Marine Toxins: An Overview

    Science.gov (United States)

    Fusetani, Nobuhiro

    Oceans provide enormous and diverse space for marine life. Invertebrates are conspicuous inhabitants in certain zones such as the intertidal; many are soft-bodied, relatively immobile and lack obvious physical defenses. These animals frequently have evolved chemical defenses against predators and overgrowth by fouling organisms. Marine animals may accumulate and use a variety of toxins from prey organisms and from symbiotic microorganisms for their own purposes. Thus, toxic animals are particularly abundant in the oceans. The toxins vary from small molecules to high molecular weight proteins and display unique chemical and biological features of scientific interest. Many of these substances can serve as useful research tools or molecular models for the design of new drugs and pesticides. This chapter provides an initial survey of these toxins and their salient properties.

  10. Clostridium Perfringens Toxins Involved in Mammalian Veterinary Diseases

    Science.gov (United States)

    Uzal, F. A.; Vidal, J. E.; McClane, B. A.; Gurjar, A. A.

    2013-01-01

    Clostridium perfringens is a gram-positive anaerobic rod that is classified into 5 toxinotypes (A, B, C, D, and E) according to the production of 4 major toxins, namely alpha (CPA), beta (CPB), epsilon (ETX) and iota (ITX). However, this microorganism can produce up to 16 toxins in various combinations, including lethal toxins such as perfringolysin O (PFO), enterotoxin (CPE), and beta2 toxin (CPB2). Most diseases caused by this microorganism are mediated by one or more of these toxins. The role of CPA in intestinal disease of mammals is controversial and poorly documented, but there is no doubt that this toxin is essential in the production of gas gangrene of humans and several animal species. CPB produced by C. perfringens types B and C is responsible for necrotizing enteritis and enterotoxemia mainly in neonatal individuals of several animal species. ETX produced by C. perfringens type D is responsible for clinical signs and lesions of enterotoxemia, a predominantly neurological disease of sheep and goats. The role of ITX in disease of animals is poorly understood, although it is usually assumed that the pathogenesis of intestinal diseases produced by C. perfringens type E is mediated by this toxin. CPB2, a necrotizing and lethal toxin that can be produced by all types of C. perfringens, has been blamed for disease in many animal species, but little information is currently available to sustain or rule out this claim. CPE is an important virulence factor for C. perfringens type A gastrointestinal disease in humans and dogs; however, the data implicating CPE in other animal diseases remains ambiguous. PFO does not seem to play a direct role as the main virulence factor for animal diseases, but it may have a synergistic role with CPA-mediated gangrene and ETX-mediated enterotoxemia. The recent improvement of animal models for C. perfringens infection and the use of toxin gene knock-out mutants have demonstrated the specific pathogenic role of several toxins of C

  11. Haemolysis induced by α-toxin from Staphylococcus aureus requires P2X receptor activation

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Leipziger, Jens Georg; Prætorius, Helle

    2011-01-01

    -forming bacterial toxins. In this context, it is essential to know whether this is specific to HlyA-induced cell damage or if other bacterial pore-forming toxins involve purinergic signals to orchestrate haemolysis. Here, we investigate if the haemolysis produced by α-toxin from Staphylococcus aureus involves P2...... receptor activation. We observed that α-toxin-induced haemolysis is completely blocked by the unselective P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Moreover, several selective blockers of P2X1 and P2X7 ionotropic receptors abolished haemolysis in murine and equine...... erythrocytes. Inhibitors of pannexin channels partially reduced the α-toxin induced lysis. Thus, we conclude that α-toxin, similar to HlyA from E. coli produces cell damage by specific activation of a purinergic signalling cascade. These data indicate that pore-forming toxins in general require purinergic...

  12. [Toxins as a biological weapon].

    Science.gov (United States)

    Płusa, Tadeusz

    2015-09-01

    The criteria for recognizing a chemical compound for the toxin are vague and gave it the possibility of inclusion in this group a number of biological agents. Toxins list is extensive, but the interest is focused on bacterial toxins, poisons derived from snake venoms, algae and plant proteins, and small molecules. Particular attention is focused on the so-called "sea" toxins, which include tetrodotoxin, brevetoxin and saxitoxin. This indicates the search for a new hitherto unknown potential bioterrorist threats. © 2015 MEDPRESS.

  13. Structural interactions of a voltage sensor toxin with lipid membranes.

    Science.gov (United States)

    Mihailescu, Mihaela; Krepkiy, Dmitriy; Milescu, Mirela; Gawrisch, Klaus; Swartz, Kenton J; White, Stephen

    2014-12-16

    Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligand-activated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor.

  14. Characterization of Hemagglutinin Negative Botulinum Progenitor Toxins

    Directory of Open Access Journals (Sweden)

    Suzanne R. Kalb

    2017-06-01

    Full Text Available Botulism is a disease involving intoxication with botulinum neurotoxins (BoNTs, toxic proteins produced by Clostridium botulinum and other clostridia. The 150 kDa neurotoxin is produced in conjunction with other proteins to form the botulinum progenitor toxin complex (PTC, alternating in size from 300 kDa to 500 kDa. These progenitor complexes can be classified into hemagglutinin positive or hemagglutinin negative, depending on the ability of some of the neurotoxin-associated proteins (NAPs to cause hemagglutination. The hemagglutinin positive progenitor toxin complex consists of BoNT, nontoxic non-hemagglutinin (NTNH, and three hemagglutinin proteins; HA-70, HA-33, and HA-17. Hemagglutinin negative progenitor toxin complexes contain BoNT and NTNH as the minimally functional PTC (M-PTC, but not the three hemagglutinin proteins. Interestingly, the genome of hemagglutinin negative progenitor toxin complexes comprises open reading frames (orfs which encode for three proteins, but the existence of these proteins has not yet been extensively demonstrated. In this work, we demonstrate that these three proteins exist and form part of the PTC for hemagglutinin negative complexes. Several hemagglutinin negative strains producing BoNT/A, /E, and /F were found to contain the three open reading frame proteins. Additionally, several BoNT/A-containing bivalent strains were examined, and NAPs from both genes, including the open reading frame proteins, were associated with BoNT/A. The open reading frame encoded proteins are more easily removed from the botulinum complex than the hemagglutinin proteins, but are present in several BoNT/A and /F toxin preparations. These are not easily removed from the BoNT/E complex, however, and are present even in commercially-available purified BoNT/E complex.

  15. Heat stability and effect of pH on enzyme activity of polyphenol oxidase in buriti (Mauritia flexuosa Linnaeus f.) fruit extract.

    Science.gov (United States)

    de Oliveira Carvalho, Jhonatam; Orlanda, José Fábio França

    2017-10-15

    Polyphenol oxidase (PPO) was extracted and characterized from ripe fruit of Mauritia flexuosa. Buriti PPO showed optimum activity at pH 7.0 and 35°C, with complete inactivation in between 2.0≤pH>10, using catechol as substrate. The enzyme had optimum temperaturet 35°C and was relatively stable at 77°C, with 59.93% loss of activity. These results demonstrate that the enzyme has heat stability at higher temperatures and the possibility of being used to construct biosensors and other analytical methods in various fields of science. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The most important marine bacterial toxins; a review

    Directory of Open Access Journals (Sweden)

    Akram Najafi

    2016-07-01

    Full Text Available Background: Bacterial toxins are toxic compounds which are produced in order to present microbial pathogenicity or to combat with the host immune system response. There is a cumulating evidence indicating bacterial origin for marine toxins such as tetrodotoxin, palytoxin, neosurugatoxin, etc. The most important marine toxins produced by different marine bacteria, their origin, structure and mechanisms of action were evaluated in a systematic review. Materials & Methods: Marine bacteria, marine bacterial toxins, and their mechanisms of action and structure were keywords for a comprehensive search in online databases including Pubmed, Science Direct, Google Scholar and Scirus. A total of 120 papers were evaluated, however, by omitting similar reports, 103 papers were included in the study. Results: The most of marine bacterial toxins are classified in one of the following groups: neurotoxins, hepatotoxins and cytotoxins. These toxins have distinct mechanisms of action including blocking of sodium channels in nerve cells, functioning as agonists of acetylcholine receptors, inhibiting of membrane pumps, the inhibition of protein phosphatases 1 and 2A types' enzyme activities and inhibiting of protein synthesis. Conclusion: The clarification of the marine bacterial toxins structures and their mechanisms of action may be helpful for novel drug design, therapeutic measures and to overcome against bacterial pathogenicity.

  17. Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

    Directory of Open Access Journals (Sweden)

    Beatriz Reguera

    2014-01-01

    Full Text Available Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP, even at low cell densities (<103 cells·L−1. They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins, and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated.

  18. Toxins Best Paper Award 2015

    Directory of Open Access Journals (Sweden)

    Vernon L. Tesh

    2015-03-01

    Full Text Available In order to recognize outstanding papers related to biotoxins and toxinology that have been published in Toxins, the Editorial Board established an annual “Toxins Best Paper Award”. We are pleased to announce the first “Toxins Best Paper Award” for 2015. Nominations were selected by the Editorial Board members, with all papers published in 2011 eligible for consideration. Reviews and original research articles were evaluated separately. Following review and voting by the Toxins Best Paper Award Committee, the following three papers have won Toxins Best Paper Awards for 2015:[...

  19. [Protein toxins of Staphylococcus aureus].

    Science.gov (United States)

    Shamsutdinov, A F; Tiurin, Iu A

    2014-01-01

    Main scientific-research studies regarding protein bacterial toxins of the most widespread bacteria that belong to Staphylococcus spp. genus and in particular the most pathogenic species for humans--Staphylococcus aureus, are analyzed. Structural and biological properties of protein toxins that have received the name of staphylococcus pyrogenic toxins (PTSAg) are presented. Data regarding genetic regulation of secretion and synthesis of these toxins and 3 main regulatory genetic systems (agr--accessory gene regulator, xpr--extracellular protein regulator, sar--staphylococcal accessory regulator) that coordinate synthesis of the most important protein toxins and enzymes for virulence of S. aureus, are presented.

  20. Secondary metabolite toxins and nutrition of plant pathogenic fungi.

    Science.gov (United States)

    Howlett, Barbara J

    2006-08-01

    Fungal pathogens derive nutrition from the plants they invade. Some fungi can subvert plant defence responses such as programmed cell death to provide nutrition for their growth and colonisation. Secondary metabolite toxins produced by fungi often play a role in triggering these responses. Knowledge of the biosynthesis of these toxins, and the availability of fungal genome sequences and gene disruption techniques, allows the development of tools for experiments aimed at discovering the role of such toxins in triggering plant cell death and plant disease.

  1. Health Risk Assessment for Cyanobacterial Toxins in Seafood

    Directory of Open Access Journals (Sweden)

    Andrew Humpage

    2012-03-01

    Full Text Available Cyanobacteria (blue-green algae are abundant in fresh, brackish and marine waters worldwide. When toxins produced by cyanobacteria are present in the aquatic environment, seafood harvested from these waters may present a health hazard to consumers. Toxicity hazards from seafood have been internationally recognised when the source is from marine algae (dinoflagellates and diatoms, but to date few risk assessments for cyanobacterial toxins in seafood have been presented. This paper estimates risk from seafood contaminated by cyanobacterial toxins, and provides guidelines for safe human consumption.

  2. Autoproteolytic Activation of Bacterial Toxins

    Directory of Open Access Journals (Sweden)

    Aimee Shen

    2010-05-01

    Full Text Available Protease domains within toxins typically act as the primary effector domain within target cells. By contrast, the primary function of the cysteine protease domain (CPD in Multifunctional Autoprocessing RTX-like (MARTX and Clostridium sp. glucosylating toxin families is to proteolytically cleave the toxin and release its cognate effector domains. The CPD becomes activated upon binding to the eukaryotic-specific small molecule, inositol hexakisphosphate (InsP6, which is found abundantly in the eukaryotic cytosol. This property allows the CPD to spatially and temporally regulate toxin activation, making it a prime candidate for developing anti-toxin therapeutics. In this review, we summarize recent findings related to defining the regulation of toxin function by the CPD and the development of inhibitors to prevent CPD-mediated activation of bacterial toxins.

  3. A Vero Cell Based Fluorescence Assay to Assess Relative Toxicities of Shiga Toxin 2 Subtypes from Escherichia coli

    Science.gov (United States)

    Shiga toxin-producing Escherichia coli is a leading cause worldwide of human gastroenteritis from food and waterborne sources. Shiga toxins 1 and 2 are important virulence factors linked to severe human illness. In particular, Shiga toxin 2 is composed of a diverse and heterogeneous group of subty...

  4. Cloning and sequence analysis of genes encoding Staphylococcus hyicus exfoliative toxin types A, B, C, and D

    DEFF Research Database (Denmark)

    Ahrens, Peter; Andresen, Lars Ole

    2004-01-01

    Exfoliative toxins produced by certain strains of Staphylococcus hyicus mediate exudative epidermitis in pigs. In this study the genes coding for four different exfoliative toxin from S. hyicus (ExhA, ExhB, ExhC, and ExhD) were cloned and sequenced. The coding sequence of the four toxin genes ran...

  5. Structural Insights into Clostridium perfringens Delta Toxin Pore Formation.

    Directory of Open Access Journals (Sweden)

    Jessica Huyet

    Full Text Available Clostridium perfringens Delta toxin is one of the three hemolysin-like proteins produced by C. perfringens type C and possibly type B strains. One of the others, NetB, has been shown to be the major cause of Avian Nectrotic Enteritis, which following the reduction in use of antibiotics as growth promoters, has become an emerging disease of industrial poultry. Delta toxin itself is cytotoxic to the wide range of human and animal macrophages and platelets that present GM2 ganglioside on their membranes. It has sequence similarity with Staphylococcus aureus β-pore forming toxins and is expected to heptamerize and form pores in the lipid bilayer of host cell membranes. Nevertheless, its exact mode of action remains undetermined. Here we report the 2.4 Å crystal structure of monomeric Delta toxin. The superposition of this structure with the structure of the phospholipid-bound F component of S. aureus leucocidin (LukF revealed that the glycerol molecules bound to Delta toxin and the phospholipids in LukF are accommodated in the same hydrophobic clefts, corresponding to where the toxin is expected to latch onto the membrane, though the binding sites show significant differences. From structure-based sequence alignment with the known structure of staphylococcal α-hemolysin, a model of the Delta toxin pore form has been built. Using electron microscopy, we have validated our model and characterized the Delta toxin pore on liposomes. These results highlight both similarities and differences in the mechanism of Delta toxin (and by extension NetB cytotoxicity from that of the staphylococcal pore-forming toxins.

  6. Application of Botulinum toxin Type A: An arsenal in dentistry

    OpenAIRE

    Lakshmana B Rao; Rajashekar Sangur; S Pradeep

    2011-01-01

    An extremely effective way of preventing damage to and enhancing treatment of dental hard tissues and restorations would be to ′′de-programme′′ the muscles responsible for excessive destructive forces and other gnathological-related diseases. The new paradigm is the intramuscular injection of Botulinum toxin type A (BOTOX) into the affected muscles. It is a natural protein produced by anaerobic bacterium, Clostridium botulinum. The toxin inhibits the release of acetylcholine (ACH), a neurotra...

  7. Toxin production in Dinophysis and the fate of these toxins in marine mussels

    DEFF Research Database (Denmark)

    Nielsen, Lasse Tor

    decisive for its potential to cause toxin accumulation in bivalves. One major aim of this thesis was to unravel the factors that determine the toxicity of Dinophysis populations, and for that purpose, I studied the biology, ecology and toxicology of the two widespread Dinophysis species, D. acuminata and D....... The ecological roles of OA/DTX and PTX are currently unknown, but our results accentuate the potential for extracellular functions. I also took advantage of the recent insights into Dinophysis culturing to produce the first study on accumulation of DSP toxins from Dinophysis in a bivalve species. Our results...... showed that the bivalve (Mytilus edulis) retained the toxins very efficiently, and exceeded the regulatory limit for OA equivalents within only a few hours of feeding. Accumulation continued linearly with time for the entire one-week study period, eventually causing mussels to be highly toxic...

  8. Review of the inhibition of biological activities of food-related selected toxins by natural compounds.

    Science.gov (United States)

    Friedman, Mendel; Rasooly, Reuven

    2013-04-23

    There is a need to develop food-compatible conditions to alter the structures of fungal, bacterial, and plant toxins, thus transforming toxins to nontoxic molecules. The term 'chemical genetics' has been used to describe this approach. This overview attempts to survey and consolidate the widely scattered literature on the inhibition by natural compounds and plant extracts of the biological (toxicological) activity of the following food-related toxins: aflatoxin B1, fumonisins, and ochratoxin A produced by fungi; cholera toxin produced by Vibrio cholerae bacteria; Shiga toxins produced by E. coli bacteria; staphylococcal enterotoxins produced by Staphylococcus aureus bacteria; ricin produced by seeds of the castor plant Ricinus communis; and the glycoalkaloid α-chaconine synthesized in potato tubers and leaves. The reduction of biological activity has been achieved by one or more of the following approaches: inhibition of the release of the toxin into the environment, especially food; an alteration of the structural integrity of the toxin molecules; changes in the optimum microenvironment, especially pH, for toxin activity; and protection against adverse effects of the toxins in cells, animals, and humans (chemoprevention). The results show that food-compatible and safe compounds with anti-toxin properties can be used to reduce the toxic potential of these toxins. Practical applications and research needs are suggested that may further facilitate reducing the toxic burden of the diet. Researchers are challenged to (a) apply the available methods without adversely affecting the nutritional quality, safety, and sensory attributes of animal feed and human food and (b) educate food producers and processors and the public about available approaches to mitigating the undesirable effects of natural toxins that may present in the diet.

  9. Enterohemorrhagic Escherichia coli infection stimulates Shiga toxin 1 macropinocytosis and transcytosis across intestinal epithelial cells.

    Science.gov (United States)

    Lukyanenko, Valeriy; Malyukova, Irina; Hubbard, Ann; Delannoy, Michael; Boedeker, Edgar; Zhu, Chengru; Cebotaru, Liudmila; Kovbasnjuk, Olga

    2011-11-01

    Gastrointestinal infection with Shiga toxins producing enterohemorrhagic Escherichia coli causes the spectrum of gastrointestinal and systemic complications, including hemorrhagic colitis and hemolytic uremic syndrome, which is fatal in ∼10% of patients. However, the molecular mechanisms of Stx endocytosis by enterocytes and the toxins cross the intestinal epithelium are largely uncharacterized. We have studied Shiga toxin 1 entry into enterohemorrhagic E. coli-infected intestinal epithelial cells and found that bacteria stimulate Shiga toxin 1 macropinocytosis through actin remodeling. This enterohemorrhagic E. coli-caused macropinocytosis occurs through a nonmuscle myosin II and cell division control 42 (Cdc42)-dependent mechanism. Macropinocytosis of Shiga toxin 1 is followed by its transcytosis to the basolateral environment, a step that is necessary for its systemic spread. Inhibition of Shiga toxin 1 macropinocytosis significantly decreases toxin uptake by intestinal epithelial cells and in this way provides an attractive, antibiotic-independent strategy for prevention of the harmful consequences of enterohemorrhagic E. coli infection.

  10. Evaluation of antidiphtheria toxin nanobodies

    Directory of Open Access Journals (Sweden)

    Ghada H Shaker

    2010-06-01

    Full Text Available Ghada H ShakerDepartment of Microbiology and Immunology, Faculty of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi ArabiaAbstract: Nanobodies are the smallest fragments of naturally occurring single-domain antibodies that have evolved to be fully functional in the absence of a light chain. Conventional antibodies are glycoproteins comprising two heavy and two light chains. Surprisingly, all members of the Camelidae family possess a fraction of antibodies devoid of both light chains and the first constant domain. These types of antibodies are known as heavy-chain antibody (HcAb nanobodies. There are three subclasses of IgG in dromedaries, namely IgG1, IgG2, and IgG3 of which IgG2 and IgG3 are of the HcAb type. These heavy chain antibodies constitute approximately 50% of the IgG in llama serum and as much as 75% of the IgG in camel serum. In the present work, the different IgG subclasses from an immunized camel (Camelus dromedarius with divalent diphtheria-tetanus vaccine were purified using their different affinity for protein A and protein G and their absorbance measured at 280 nm. Purity control and characterization by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis of IgG subclasses was done under reducing conditions. Protein bands were visualized after staining with Coomassie Blue, showing two bands at 50 kDa and 30 kDa for IgG1, while IgG2 and IgG3 produced only one band at 46 kDa and 43 kDa, respectively. An enzyme-linked immunosorbent assay test using diphtheria toxin and purified IgG subclasses from the immunized camel were performed to evaluate their efficiency. Compared with conventional IgG1, heavy chain antibodies (nanobodies were shown to be more efficient in binding to diphtheria toxin antigen. This study revealed the possibility of using IgG2 and IgG3 nanobodies as an effective antitoxin for the treatment of diphtheria in humans.Keywords: camel, heavy chain antibody, HcAb, nanobodies, immunoglobulin, Ig

  11. Shellfish Toxins Targeting Voltage-Gated Sodium Channels

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2013-11-01

    Full Text Available Voltage-gated sodium channels (VGSCs play a central role in the generation and propagation of action potentials in excitable neurons and other cells and are targeted by commonly used local anesthetics, antiarrhythmics, and anticonvulsants. They are also common targets of neurotoxins including shellfish toxins. Shellfish toxins are a variety of toxic secondary metabolites produced by prokaryotic cyanobacteria and eukaryotic dinoflagellates in both marine and fresh water systems, which can accumulate in marine animals via the food chain. Consumption of shellfish toxin-contaminated seafood may result in potentially fatal human shellfish poisoning. This article provides an overview of the structure, bioactivity, and pharmacology of shellfish toxins that act on VGSCs, along with a brief discussion on their pharmaceutical potential for pain management.

  12. Mosquitocidal bacterial toxins: diversity, mode of action and resistance phenomena

    Directory of Open Access Journals (Sweden)

    Charles Jean-François

    2000-01-01

    Full Text Available Bacteria active against dipteran larvae (mosquitoes and black flies include a wide variety of Bacillus thuringiensis and B. sphaericus strains, as well as isolates of Brevibacillus laterosporus and Clostridium bifermentans. All display different spectra and levels of activity correlated with the nature of the toxins, mainly produced during the sporulation process. This paper describes the structure and mode of action of the main mosquitocidal toxins, in relationship with their potential use in mosquito and/or black fly larvae control. Investigations with laboratory and field colonies of mosquitoes that have become highly resistant to the B. sphaericus Bin toxin have shown that several mechanisms of resistance are involved, some affecting the toxin/receptor binding step, others unknown.

  13. Evaluation of Cholera Toxin Expression in Different Populations of Vibrio cholera

    OpenAIRE

    Sedigheh Ebrahimi Kasgari; Mahnaz Nourani; Yousef Yahyapour; Seyed Ehsanollah Mousavi; Enayatollah Kalantar; Hami Kaboosi; Seyed Mahmoud Amin Marashi

    2015-01-01

    Background: Cholera is one of the most diseases of human. Cholera toxin is the most important pathogenic factor in humans that causes diarrhea. The cholera toxin is produced by V. cholerae and CTXфPhage. Objectives: In this study, we have investigated the production cholera toxin with different density of Vibrio cholerae. Materials and Methods: With this propose we inoculated classical strain O1 of Vibrio cholerae ATCC 14035 and Vibrio cholerae O1biovar El Tor N16961 into th...

  14. Cyanobacterial toxins: removal during drinking water treatment, and human risk assessment.

    OpenAIRE

    Hitzfeld, B C; Höger, S J; Dietrich, D R

    2000-01-01

    Cyanobacteria (blue-green algae) produce toxins that may present a hazard for drinking water safety. These toxins (microcystins, nodularins, saxitoxins, anatoxin-a, anatoxin-a(s), cylindrospermopsin) are structurally diverse and their effects range from liver damage, including liver cancer, to neurotoxicity. The occurrence of cyanobacteria and their toxins in water bodies used for the production of drinking water poses a technical challenge for water utility managers. With respect to their re...

  15. Molecular cloning of Clostridium septicum vaccine strain alpha toxin gene in E. coli

    OpenAIRE

    Bozorgkhoo; Pilehchian Langroudi; Khaki; Jabbari; Moradi Bidhendi; Moosawi Shoshtari

    2014-01-01

    Clostridium septicum a Gram positive anaerobic bacterium produces several toxins including alpha, beta, gamma and delta. C. septicum alpha toxin is lethal and is responsible for a serious disease known as gas gangrene. The aim of the present study was to molecular cloning and sequencing of C. septicum vaccine strain alpha toxin gene. Genomic DNA was extracted using standard phenol and chloroform extraction method, and the target gene was amplified through PCR by specific primers. Quality and ...

  16. A Structure-Function Analysis of Shiga-Like Toxin Type 2 of Enterohemorrhagic Escherichia Coli

    Science.gov (United States)

    1990-05-07

    implicated in bloody diarrhea and hemorrhagic colitis are classified as enterohemorrhagic E. coli ( EHEC ). Currently, the EHEC group consists of 3... EHEC with hemorrhagic colitis and the hemolytic uremic syndrome. Furthermore, recent reports have indicated that SLT- producing E. coli may play a...the Shiga toxin of Shigella dysenteriae I and the Shiga-like toxins of EHEC and in the identification of the toxin receptors, the biophysical

  17. Alternaria Toxins: Potential Virulence Factors and Genes Related to Pathogenesis

    Science.gov (United States)

    Meena, Mukesh; Gupta, Sanjay K.; Swapnil, Prashant; Zehra, Andleeb; Dubey, Manish K.; Upadhyay, Ram S.

    2017-01-01

    Alternaria is an important fungus to study due to their different life style from saprophytes to endophytes and a very successful fungal pathogen that causes diseases to a number of economically important crops. Alternaria species have been well-characterized for the production of different host-specific toxins (HSTs) and non-host specific toxins (nHSTs) which depend upon their physiological and morphological stages. The pathogenicity of Alternaria species depends on host susceptibility or resistance as well as quantitative production of HSTs and nHSTs. These toxins are chemically low molecular weight secondary metabolites (SMs). The effects of toxins are mainly on different parts of cells like mitochondria, chloroplast, plasma membrane, Golgi complex, nucleus, etc. Alternaria species produce several nHSTs such as brefeldin A, tenuazonic acid, tentoxin, and zinniol. HSTs that act in very low concentrations affect only certain plant varieties or genotype and play a role in determining the host range of specificity of plant pathogens. The commonly known HSTs are AAL-, AK-, AM-, AF-, ACR-, and ACT-toxins which are named by their host specificity and these toxins are classified into different family groups. The HSTs are differentiated on the basis of bio-statistical and other molecular analyses. All these toxins have different mode of action, biochemical reactions and signaling mechanisms to cause diseases. Different species of Alternaria produced toxins which reveal its biochemical and genetic effects on itself as well as on its host cells tissues. The genes responsible for the production of HSTs are found on the conditionally dispensable chromosomes (CDCs) which have been well characterized. Different bio-statistical methods like basic local alignment search tool (BLAST) data analysis used for the annotation of gene prediction, pathogenicity-related genes may provide surprising knowledge in present and future. PMID:28848500

  18. Alternaria Toxins: Potential Virulence Factors and Genes Related to Pathogenesis

    Directory of Open Access Journals (Sweden)

    Mukesh Meena

    2017-08-01

    Full Text Available Alternaria is an important fungus to study due to their different life style from saprophytes to endophytes and a very successful fungal pathogen that causes diseases to a number of economically important crops. Alternaria species have been well-characterized for the production of different host-specific toxins (HSTs and non-host specific toxins (nHSTs which depend upon their physiological and morphological stages. The pathogenicity of Alternaria species depends on host susceptibility or resistance as well as quantitative production of HSTs and nHSTs. These toxins are chemically low molecular weight secondary metabolites (SMs. The effects of toxins are mainly on different parts of cells like mitochondria, chloroplast, plasma membrane, Golgi complex, nucleus, etc. Alternaria species produce several nHSTs such as brefeldin A, tenuazonic acid, tentoxin, and zinniol. HSTs that act in very low concentrations affect only certain plant varieties or genotype and play a role in determining the host range of specificity of plant pathogens. The commonly known HSTs are AAL-, AK-, AM-, AF-, ACR-, and ACT-toxins which are named by their host specificity and these toxins are classified into different family groups. The HSTs are differentiated on the basis of bio-statistical and other molecular analyses. All these toxins have different mode of action, biochemical reactions and signaling mechanisms to cause diseases. Different species of Alternaria produced toxins which reveal its biochemical and genetic effects on itself as well as on its host cells tissues. The genes responsible for the production of HSTs are found on the conditionally dispensable chromosomes (CDCs which have been well characterized. Different bio-statistical methods like basic local alignment search tool (BLAST data analysis used for the annotation of gene prediction, pathogenicity-related genes may provide surprising knowledge in present and future.

  19. Comments on "Screening and identification of novel ochratoxin A-producing fungi from grapes. Toxins 2016,8,833" - in reporting ochratoxin A production from strains of Aspergillus, Penicillium and talaromcyes

    DEFF Research Database (Denmark)

    Perrone, Giancarlo; Logrieco, Antonio F.; Frisvad, Jens Christian

    2017-01-01

    Recently a species in the genus Talaromyces, a uniseriate species of Aspergillus section Nigri and an isolate each of two widespread species, Penicillium rubens and P. commune, were reported to produce ochratoxin A. This claim was based on insufficient biological and chemical data. We propose a l...

  20. [Molecular mechanism of action of tetanus toxin and botulinum neurotoxins].

    Science.gov (United States)

    Poulain, B

    1994-02-01

    Tetanus toxin and botulinum neurotoxins are di-chain proteins of 150 kD molecular weight. They are produced by bacteria of the Clostridium genus. These toxins act on the nervous system by inhibiting neurotransmitter release (glycine and GABA in the case of tetanus toxin; acetylcholine in the case of botulinum neurotoxins) thus inducing the spastic or flaccid paralysis that characterizes tetanus and botulism, respectively. Their cellular mechanism of action involves three main steps, namely binding to the neurone membrane, internalization and intracellular blockade of the release mechanism for neurotransmitters. Membrane acceptors for these toxins are not yet fully identified; they would consist of membrane gangliosides and proteins. The internalization step would be achieved by endocytosis. Recent findings show that both binding and internalization are mediated only by the heavy chain of the toxins whereas the intracellular blockade of neurotransmitter release involves their light chain alone. The light chain has been identified as a zinc metalloprotease and its substrates would be proteins involved in the neurotransmitter release mechanism. The target of tetanus toxin and of botulinum neurotoxin type B is VAMP/synaptobrevin, a membrane protein of the synaptic vesicles of nerve cell terminals.

  1. The structure and mode of action of the dinoflagellate toxins

    Directory of Open Access Journals (Sweden)

    Akram Najafi

    2016-07-01

    Full Text Available Background: Dinoflagellates are the major causative agents of harmful algal blooms. In different studies, it has been shown that many dinoflagellate species produce various natural toxins. Saxitoxin, brevetoxin, yessotoxin, etc can be considered as the most important neurotoxins. The most important dinoflagellate toxins structures, their origin, structure and mechanisms of action were evaluated in a systematic review. Materials & Methods: Marine dinoflagellates, marine toxins, and their mechanisms of action and structure were keywords for a comprehensive search in online databases including Pubmed, Science Direct, Google Scholar and Scirus. A total of 95 papers were evaluated, however, by omitting similar reports, 68 papers were included in the study. Results: Dinoflagellates toxins are usually polycyclic ether and polyketaide compounds that have distinct mechanisms of action including alteration in different ion channels and/or pumps at cell membrane, effect on the normal functioning of neuronal and other excitable tissues, inhibition of serine/threonine phosphoprotein phosphatases, disrupting major mechanisms of controlling cellular functions, and alteration in cellular cytoskeleton. However, the precise mechanisms of action of few toxins are not determined yet. Conclusion: The clarification of the dinoflagellate toxins structures and their mechanisms of action may be helpful for novel drug design, therapeutic measures and to overcome against marine toxicity. 

  2. Evaluation of Cholera Toxin Expression in Different Populations of Vibrio cholera

    Directory of Open Access Journals (Sweden)

    Sedigheh Ebrahimi Kasgari

    2015-02-01

    Full Text Available Background: Cholera is one of the most diseases of human. Cholera toxin is the most important pathogenic factor in humans that causes diarrhea. The cholera toxin is produced by V. cholerae and CTXфPhage. Objectives: In this study, we have investigated the production cholera toxin with different density of Vibrio cholerae. Materials and Methods: With this propose we inoculated classical strain O1 of Vibrio cholerae ATCC 14035 and Vibrio cholerae O1biovar El Tor N16961 into the AKI medium. Then, the total mRNA was determined by standard procedure which was converted into total cDNA. Results: Cholra toxin production was determined by qPCR and maximum production of cholera toxin was at 1010 cfu/mL. Conclusions: In conclusion, production of cholera toxin was minimized almost up to zero at 1010.5 cfu/mL; which could be due to presence of high level concentration of autoinducer.

  3. Poison as cure: a clinical review of botulinum toxin as an invaluable drug

    Directory of Open Access Journals (Sweden)

    J. Bali

    2005-12-01

    Full Text Available Botulinum toxin is the most potent toxin known. It is readily absorbed from mucosal surfaces. If dispersed as an aerosol or mixed in the food or water it can lead to a large outbreak of botulism. The disease presents as a symmetric descending paralysis in an afebrile patient. Cranial nerve involvement with diplopia, dysarthria, dysphonia, dysphagia and respiratory paralysis is seen after a variable incubation period. The treatment is mainly supportive. The source of the toxin is Clostridium botulinum, an anaerobic gram-positive spore-forming organism. Some other species of Clostridium like C. butyricum and C. baratii also produce the toxin. The toxin is heat labile and can be inactivated by heating at 100°C for 10 minutes. The toxin acts at the peripheral cholinergic nerve terminals at the neuromuscular junctions, postganglionic parasympathetic ganglia, etc, and affects neurotransmitter release by inhibiting exocytosis. Clinical uses in various medical fields were found for it.

  4. Expression of Tetanus Toxin Subfragments In Vitro and Characterization of Epitopes

    NARCIS (Netherlands)

    Andersen-Beckh, Bettina; Binz, Thomas; Kurazono, Hisao; Mayer, Thomas; Eisel, Ulrich; Niemann, Heiner

    1989-01-01

    To define epitopes of tetanus toxin, we compared four different in vitro systems in terms of their ability to produce tetanus toxin-specific subfragments from cloned DNA. A transcription-translation system developed from a nontoxigenic strain of Clostridium tetani was found to yield predominantly

  5. Imaging surface plasmon resonance detection for T-2 toxin in wheat

    Science.gov (United States)

    T-2 toxin is a trichothecene (Type A) mycotoxin harmful to humans and animals. It is produced by mainly Fusarium species, particularly F. sporotrichoides. Fusarium species often contaminate grains such as corn, wheat, barley, oats, rice and rye. T-2 toxin contamination in grains has been observed mo...

  6. Cyanobacteria, Toxins and Indicators: Full-Scale Monitoring & Bench-Scale Treatment Studies

    Science.gov (United States)

    Summary of: 1) Lake Erie 2014 bloom season full-scale treatment plant monitoring data for cyanobacteria and cyanobacteria toxins; 2) Follow-up work to examine the impact of pre-oxidation on suspensions of intact toxin-producing cyanobacterial cells.

  7. Distribution of diarrhetic shellfish poisoning toxins in consignments of blue mussel

    DEFF Research Database (Denmark)

    Jørgensen, Kevin; Jensen, Lene Bai

    2004-01-01

    Data describing the distribution of diarrhetic shellfish poisoning toxins in 13 consignments of Danish-produced blue mussels are reported. The content of diarrhetic shellfish poisoning toxins was measured by a liquid chromatography coupled with tandem mass spectrometry detection method, and mean...

  8. 9 CFR 114.16 - Producing subsidiaries.

    Science.gov (United States)

    2010-01-01

    ... AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS PRODUCTION REQUIREMENTS FOR BIOLOGICAL PRODUCTS § 114.16 Producing subsidiaries. A serial or subserial of a biological product may be...

  9. OBTAINING OF MONOCLONAL ANTIBODIES AGAINST CHOLERA TOXIN AND HEAT LABILE ENTEROTOXIN OF E. coli FOR DEVELOPMENT OF THE TOXINS DIPLEX ANALYSIS IN ENVIRONMENTAL SPECIMENS

    Directory of Open Access Journals (Sweden)

    Eu. V. Grishin

    2013-08-01

    Full Text Available The present study focuses on development of monoclonal antibodies (MAbs which specifically interact with cholera toxin or heat labile enterotoxin of E. coli. Such monoclonal antibodies MAbs are possessed of ability to identify cholera toxin or heat labile enterotoxin in different immunochemical assays. We obtained hybridoma clones which produced monoclonal antibodies of IgG isotypes to cholera toxin and heat labile enterotoxin. On application of the method of serial dilutions we selected the clones which produced monoclonal antibodies with specific activity against only one of the toxins. We found the 16 pairs of monoclonal antibodies to cholera toxin and 28 ones to heat labile enterotoxin. By means of these monoclonal antibodies it was possible to realize the quantitative analysis of theses toxins in sandwich immunoassay ELISA and diplex sandwich xMAP-assay. The limits of detection of cholera toxin and heat labile enterotoxin in ELISA in control buffer were 0.2 and 0.4 ng/ml, respectively, and in xMAP assay — 0.01 and 0.08 ng/ml, respectively. In probes of cow milk, meat soup, pond water and nasopharyngeal washes cholera toxin was detected in the both assays with the same limits of detections, but heat labile enterotoxin limits of detections were above the ones in control buffers.

  10. The Biology of the Cytolethal Distending Toxins

    Directory of Open Access Journals (Sweden)

    Teresa Frisan

    2011-03-01

    Full Text Available The cytolethal distending toxins (CDTs, produced by a variety of Gram-negative pathogenic bacteria, are the first bacterial genotoxins described, since they cause DNA damage in the target cells. CDT is an A-B2 toxin, where the CdtA and CdtC subunits are required to mediate the binding on the surface of the target cells, allowing internalization of the active CdtB subunit, which is functionally homologous to the mammalian deoxyribonuclease I. The nature of the surface receptor is still poorly characterized, however binding of CDT requires intact lipid rafts, and its internalization occurs via dynamin-dependent endocytosis. The toxin is retrograde transported through the Golgi complex and the endoplasmic reticulum, and subsequently translocated into the nuclear compartment, where it exerts the toxic activity. Cellular intoxication induces DNA damage and activation of the DNA damage responses, which results in arrest of the target cells in the G1 and/or G2 phases of the cell cycle and activation of DNA repair mechanisms. Cells that fail to repair the damage will senesce or undergo apoptosis. This review will focus on the well-characterized aspects of the CDT biology and discuss the questions that still remain unanswered.

  11. Isolation of moulds capable of producing mycotoxins from blue mouldy Tulum cheeses produced in Turkey.

    Science.gov (United States)

    Erdogan, A; Gurses, M; Sert, S

    2003-08-15

    A total of 16 moulds was isolated and identified from 12 blue mouldy Tulum cheeses collected from retailers in Erzurum, Turkey; 12 were Penicillium roqueforti and 4 were Geotrichum candidum. The P. roqueforti isolates were grown in yeast sucrose broth at 5, 12 and 25 degrees C for 10 days, then extracted with chloroform and acetone and the extracts were examined for the presence of patulin, penicillic acid, roquefortine and PR toxin using thin layer chromatography. All of the P. roqueforti strains had toxin-producing ability at 5, 12 and 25 degrees C, eight produced only at 5 and 12 degrees C and six could not produce toxin at 5 degrees C.

  12. Food toxin detection with atomic force microscope

    Science.gov (United States)

    Externally introduced toxins or internal spoilage correlated pathogens and their metabolites are all potential sources of food toxins. To prevent and protect unsafe food, many food toxin detection techniques have been developed to detect various toxins for quality control. Although several routine m...

  13. Beta2 toxin is not involved in in vitro cell cytotoxicity caused by human and porcine cpb2-harbouring Clostridium perfringens

    NARCIS (Netherlands)

    Allaart, J.G.|info:eu-repo/dai/nl/357077776; van Asten, A.J.A.M.; Vernooij, J.C.M.|info:eu-repo/dai/nl/340304596; Gröne, A.|info:eu-repo/dai/nl/304836141

    2014-01-01

    Clostridium perfringens is a common cause of intestinal disease in animals and humans. Its pathogenicity is attributed to the toxins it can produce, including the beta2 toxin. The presence of cpb2, the gene encoding the beta2 toxin, has been associated with diarrhoea in neonatal piglets and humans.

  14. New high-affinity monoclonal antibodies against Shiga toxin 1 facilitate the detection of hybrid Stx1/Stx2 in vivo

    Science.gov (United States)

    Background: Shiga-like toxins (Stxs) are important virulence factors in gastrointestinal infections caused by Shiga toxin-producing Eschericia coli (STEC). Stx1 is almost identical to the Shiga toxin (STx) from Shigella dysenteriae, a very prevalent disease-causing microorganism in the developing wo...

  15. Shiga Toxins as Multi-Functional Proteins: Induction of Host Cellular Stress Responses, Role in Pathogenesis and Therapeutic Applications

    Directory of Open Access Journals (Sweden)

    Moo-Seung Lee

    2016-03-01

    Full Text Available Shiga toxins (Stxs produced by Shiga toxin-producing bacteria Shigella dysenteriae serotype 1 and select serotypes of Escherichia coli are primary virulence factors in the pathogenesis of hemorrhagic colitis progressing to potentially fatal systemic complications, such as hemolytic uremic syndrome and central nervous system abnormalities. Current therapeutic options to treat patients infected with toxin-producing bacteria are limited. The structures of Stxs, toxin-receptor binding, intracellular transport and the mode of action of the toxins have been well defined. However, in the last decade, numerous studies have demonstrated that in addition to being potent protein synthesis inhibitors, Stxs are also multifunctional proteins capable of activating multiple cell stress signaling pathways, which may result in apoptosis, autophagy or activation of the innate immune response. Here, we briefly present the current understanding of Stx-activated signaling pathways and provide a concise review of therapeutic applications to target tumors by engineering the toxins.

  16. Comparative evaluation of bivalent malaria rapid diagnostic tests versus traditional methods in field with special reference to heat stability testing in Central India.

    Directory of Open Access Journals (Sweden)

    Neeru Singh

    Full Text Available BACKGROUND: Malaria presents a diagnostic challenge in areas where both Plasmodium falciparum and P.vivax are co-endemic. Bivalent Rapid Diagnostic tests (RDTs showed promise as diagnostic tools for P.falciparum and P.vivax. To assist national malaria control programme in the selection of RDTs, commercially available seven malaria RDTs were evaluated in terms of their performance with special reference to heat stability. METHODOLOGY/PRINCIPAL FINDINGS: This study was undertaken in four forested districts of central India (July, 2011- March, 2012. All RDTs were tested simultaneously in field along with microscopy as gold standard. These RDTs were stored in their original packing at 25°C before transport to the field or they were stored at 35°C and 45°C upto 100 days for testing the performance of RDTs at high temperature. In all 2841 patients with fever were screened for malaria of which 26% were positive for P.falciparum, and 17% for P.vivax. The highest sensitivity of any RDT for P.falciparum was 98% (95% CI; 95.9-98.8 and lowest sensitivity was 76% (95% CI; 71.7-79.6. For P.vivax highest and lowest sensitivity for any RDT was 80% (95% CI; 94.9 - 83.9 and 20% (95% CI; 15.6-24.5 respectively. Heat stability experiments showed that most RDTs for P.falciparum showed high sensitivity at 45°C upto 90 days. While for P.vivax only two RDTs maintained good sensitivity upto day 90 when compared with RDTs kept at room temperature. Agreement between observers was excellent for positive and negative readings for both P.falciparum and P.vivax (Kappa >0.6-0.9. CONCLUSION: This is first field evaluation of RDTs regarding their temperature stability. Although RDTs are useful as diagnostic tool for P.falciparum and P.vivax even at high temperature, the quality of RDTs should be regulated and monitored more closely.

  17. Degradation and inactivation of Shiga toxins by nitrogen gas plasma.

    Science.gov (United States)

    Sakudo, Akikazu; Imanishi, Yuichiro

    2017-12-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) leads to food poisoning by causing hemorrhagic colitis and hemolytic uremic syndrome. Some STEC produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2), a relatively stable protein toxin, necessitating the development of an efficient inactivation method. Here we applied a nitrogen gas plasma apparatus to the inactivation of Stx. Samples of Stx1 and Stx2 were treated with a nitrogen gas plasma generated by a plasma device using a short high-voltage pulse applied by a static induction thyristor power supply at 1.5 kpps (kilo pulse per second). The recovered Stx samples were then analyzed for immunological and biological activities. Immunochromatography demonstrated that Stx1 and Stx2 were degraded by the gas plasma. Quantification by enzyme-linked immunosorbent assay (ELISA) showed that both toxins were efficiently degraded to less than 1/10th of their original concentration within 5 min of treatment. Western blotting further showed the gas plasma treatment degraded the A subunit, which mediates the toxicity of Stx. Moreover, an assay using HEp-2 cells as an index of cytotoxicity showed that gas plasma treatment reduced the toxic activity of Stx. Therefore, nitrogen gas plasma might be an efficient method for the inactivation of Stx.

  18. Diversity and impact of prokaryotic toxins on aquatic environments: a review.

    Science.gov (United States)

    Valério, Elisabete; Chaves, Sandra; Tenreiro, Rogério

    2010-10-01

    Microorganisms are ubiquitous in all habitats and are recognized by their metabolic versatility and ability to produce many bioactive compounds, including toxins. Some of the most common toxins present in water are produced by several cyanobacterial species. As a result, their blooms create major threats to animal and human health, tourism, recreation and aquaculture. Quite a few cyanobacterial toxins have been described, including hepatotoxins, neurotoxins, cytotoxins and dermatotoxins. These toxins are secondary metabolites, presenting a vast diversity of structures and variants. Most of cyanobacterial secondary metabolites are peptides or have peptidic substructures and are assumed to be synthesized by non-ribosomal peptide synthesis (NRPS), involving peptide synthetases, or NRPS/PKS, involving peptide synthetases and polyketide synthases hybrid pathways. Besides cyanobacteria, other bacteria associated with aquatic environments are recognized as significant toxin producers, representing important issues in food safety, public health, and human and animal well being. Vibrio species are one of the most representative groups of aquatic toxin producers, commonly associated with seafood-born infections. Some enterotoxins and hemolysins have been identified as fundamental for V. cholerae and V. vulnificus pathogenesis, but there is evidence for the existence of other potential toxins. Campylobacter spp. and Escherichia coli are also water contaminants and are able to produce important toxins after infecting their hosts. Other bacteria associated with aquatic environments are emerging as toxin producers, namely Legionella pneumophila and Aeromonas hydrophila, described as responsible for the synthesis of several exotoxins, enterotoxins and cytotoxins. Furthermore, several Clostridium species can produce potent neurotoxins. Although not considered aquatic microorganisms, they are ubiquitous in the environment and can easily contaminate drinking and irrigation water

  19. Diversity and Impact of Prokaryotic Toxins on Aquatic Environments: A Review

    Directory of Open Access Journals (Sweden)

    Rogério Tenreiro

    2010-10-01

    Full Text Available Microorganisms are ubiquitous in all habitats and are recognized by their metabolic versatility and ability to produce many bioactive compounds, including toxins. Some of the most common toxins present in water are produced by several cyanobacterial species. As a result, their blooms create major threats to animal and human health, tourism, recreation and aquaculture. Quite a few cyanobacterial toxins have been described, including hepatotoxins, neurotoxins, cytotoxins and dermatotoxins. These toxins are secondary metabolites, presenting a vast diversity of structures and variants. Most of cyanobacterial secondary metabolites are peptides or have peptidic substructures and are assumed to be synthesized by non-ribosomal peptide synthesis (NRPS, involving peptide synthetases, or NRPS/PKS, involving peptide synthetases and polyketide synthases hybrid pathways. Besides cyanobacteria, other bacteria associated with aquatic environments are recognized as significant toxin producers, representing important issues in food safety, public health, and human and animal well being. Vibrio species are one of the most representative groups of aquatic toxin producers, commonly associated with seafood-born infections. Some enterotoxins and hemolysins have been identified as fundamental for V. cholerae and V. vulnificus pathogenesis, but there is evidence for the existence of other potential toxins. Campylobacter spp. and Escherichia coli are also water contaminants and are able to produce important toxins after infecting their hosts. Other bacteria associated with aquatic environments are emerging as toxin producers, namely Legionella pneumophila and Aeromonas hydrophila, described as responsible for the synthesis of several exotoxins, enterotoxins and cytotoxins. Furthermore, several Clostridium species can produce potent neurotoxins. Although not considered aquatic microorganisms, they are ubiquitous in the environment and can easily contaminate drinking

  20. Geraniol synthase whose mRNA is induced by host-selective ACT-toxin in the ACT-toxin-insensitive rough lemon (Citrus jambhiri).

    Science.gov (United States)

    Shishido, Hodaka; Miyamoto, Yoko; Ozawa, Rika; Taniguchi, Shiduku; Takabayashi, Junji; Akimitsu, Kazuya; Gomi, Kenji

    2012-09-15

    Host-selective toxins (HSTs) produced by some strains of Alternaria alternata are selectively toxic to certain cultivars of plants. However, the role of HSTs in toxin-insensitive plants is currently unknown. Here, we studied the role of ACT-toxin using an ACT-toxin producing A. alternata strain SH20 and the ACT-toxin-insensitive plant rough lemon. Induction of some defense related genes in response to SH20 were faster or stronger than in response to the ACT-toxin deficient SH20 mutant. By sequencing subtractive PCR clones obtained from mRNA of rough lemon leaves inoculated with SH20 after subtraction with that of the ACT-toxin deficient SH20 mutant, we isolated the SH20-responsive genes in rough lemon. Among the SH20-responsive genes analyzed in this study, we isolated a terpene synthase (TPS) gene, RlemTPS3. We also determined that RlemTPS3 localizes to the chloroplast and produces the monoterpene geraniol. Copyright © 2012 Elsevier GmbH. All rights reserved.

  1. Dynamics of plc gene transcription and alpha-toxin production during growth of Clostridium perfringens strains with contrasting alpha-toxin production.

    Science.gov (United States)

    Abildgaard, Lone; Schramm, Andreas; Rudi, Knut; Højberg, Ole

    2009-10-20

    The aim of the present study was to investigate transcription dynamics of the alpha-toxin-encoding plc gene relative to two housekeeping genes (gyrA and rplL) in batch cultures of three Clostridium perfringens strains with low, intermediate, and high levels of alpha-toxin production, respectively. The plc transcript level was always low in the low alpha-toxin producing strain. For the two other strains, plc transcription showed an inducible pattern and reached a maximum level in the late exponential growth phase. The transcription levels were however inversely correlated to alpha-toxin production for the two strains. We propose that this discrepancy is due to differences in plc translation rates between the strains and that strain-specific translational rates therefore must be determined before alpha-toxin production can be extrapolated from transcript levels in C. perfringens.

  2. Dynamics of plc gene transcription and α-toxin production during growth of Clostridium perfringens strains with contrasting α-toxin production

    DEFF Research Database (Denmark)

    Abildgaard, Lone; Schramm, Andreas; Rudi, Knut

    2009-01-01

    The aim of the present study was to investigate transcription dynamics of the α-toxin-encoding plc gene relative to two housekeeping genes (gyrA and rplL) in batch cultures of three Clostridium perfringens strains with low, intermediate, and high levels of α-toxin production, respectively. The plc....... We propose that this discrepancy is due to differences in plc translation rates between the strains and that strain-specific translational rates therefore must be determined before α-toxin production can be extrapolated from transcript levels in C. perfringens....... transcript level was always low in the low α-toxin producing strain. For the two other strains, plc transcription showed an inducible pattern and reached a maximum level in the late exponential growth phase. The transcription levels were however inversely correlated to α-toxin production for the two strains...

  3. Clostridium perfringens Epsilon Toxin: A Malevolent Molecule for Animals and Man?

    Science.gov (United States)

    Stiles, Bradley G.; Barth, Gillian; Barth, Holger; Popoff, Michel R.

    2013-01-01

    Clostridium perfringens is a prolific, toxin-producing anaerobe causing multiple diseases in humans and animals. One of these toxins is epsilon, a 33 kDa protein produced by Clostridium perfringens (types B and D) that induces fatal enteric disease of goats, sheep and cattle. Epsilon toxin (Etx) belongs to the aerolysin-like toxin family. It contains three distinct domains, is proteolytically-activated and forms oligomeric pores on cell surfaces via a lipid raft-associated protein(s). Vaccination controls Etx-induced disease in the field. However, therapeutic measures are currently lacking. This review initially introduces C. perfringens toxins, subsequently focusing upon the Etx and its biochemistry, disease characteristics in various animals that include laboratory models (in vitro and in vivo), and finally control mechanisms (vaccines and therapeutics). PMID:24284826

  4. Tetanus toxin: convulsant action on mouse spinal cord neurons in culture.

    Science.gov (United States)

    Bergey, G K; MacDonald, R L; Habig, W H; Hardegree, M C; Nelson, P G

    1983-11-01

    The effects of direct application of tetanus toxin on fetal mouse spinal cord neurons in culture are described. Tetanus toxin produces increased excitation characterized by paroxysmal depolarizing events (PDE). In contrast to the abrupt onset of convulsant action produced by postsynaptic glycine antagonist strychnine, the convulsant action of tetanus occurs after a dose-dependent latent period. The onset of the convulsant action of tetanus toxin is paralleled by a reduction in observed spontaneous inhibitory synaptic potentials. Excitatory synaptic events can be identified as components of some tetanus-PDE. The toxin does not alter postsynaptic responses to the inhibitory amino acids glycine and gamma-aminobutyric acid. The latency and convulsant action of tetanus toxin are consistent with an irreversible presynaptic membrane interaction that reduces inhibitory transmission, a mechanism of action distinct from those of convulsants that antagonize inhibitory transmitters at the postsynaptic membrane.

  5. Catalytic properties and heat stabilities of novel recombinant human N-acetyltransferase 2 allozymes support existence of genetic heterogeneity within the slow acetylator phenotype.

    Science.gov (United States)

    Hein, David W; Doll, Mark A

    2017-08-01

    Human N-acetyltransferase 2 (NAT2) catalyzes the N-acetylation of numerous aromatic amine drugs such as sulfamethazine (SMZ) and hydrazine drugs such as isoniazid (INH). NAT2 also catalyzes the N-acetylation of aromatic amine carcinogens such as 2-aminofluorene and the O- and N,O-acetylation of aromatic amine and heterocyclic amine metabolites. Genetic polymorphism in NAT2 modifies drug efficacy and toxicity as well as cancer risk. Acetyltransferase catalytic activities and heat stability associated with six novel NAT2 haplotypes (NAT2*6C, NAT2*14C, NAT2*14D, NAT2*14E, NAT2*17, and NAT2*18) were compared with that of the reference NAT2*4 haplotype following recombinant expression in Escherichia coli. N-acetyltransferase activities towards SMZ and INH were significantly (p  0.05) from recombinant NAT2 4. The apparent V max catalyzed by NAT2 14C and NAT2 14D were significantly lower (p < 0.05) than the apparent V max catalyzed by NAT2 6C and NAT2 14E towards AF, ABP, and DMABP. Heat inactivation rate constants for recombinant human NAT2 14C, 14D, 14E, and 18 were significantly (p < 0.05) higher than NAT2 4. These results provide further evidence of genetic heterogeneity within the NAT2 slow acetylator phenotype.

  6. Cyanobacterial toxins: A short review on phytotoxic effect in an ...

    African Journals Online (AJOL)

    Cyanobacteria are photosynthetic prokaryotes which frequently form blooms in eutrophic water bodies. Some species of cyanobacteria are able to produce toxins (cyanotoxins) that can cause aquatic environment and diverse organisms living there to be at a serious risk. One of the more serious impacts of eutrophication on ...

  7. Effects of Clostridium perfringens iota toxin in the small intestine of mice.

    Science.gov (United States)

    Redondo, Leandro M; Redondo, Enzo A; Dailoff, Gabriela C; Leiva, Carlos L; Díaz-Carrasco, Juan M; Bruzzone, Octavio A; Cangelosi, Adriana; Geoghegan, Patricia; Fernandez-Miyakawa, Mariano E

    2017-12-01

    Iota toxin is a binary toxin solely produced by Clostridium perfringens type E strains, and is structurally related to CDT from C. difficile and CST from C. spiroforme. As type E causes hemorrhagic enteritis in cattle, it is usually assumed that associated diseases are mediated by iota toxin, although evidence in this regard has not been provided. In the present report, iota toxin intestinal effects were evaluated in vivo using a mouse model. Histological damage was observed in ileal loops treated with purified iota toxin after 4 h of incubation. Luminal iota toxin induced fluid accumulation in the small intestine in a dose dependent manner, as determined by the enteropooling and the intestinal loop assays. None of these changes were observed in the large intestine. These results suggest that C. perfringens iota toxin alters intestinal permeability, predominantly by inducing necrosis and degenerative changes in the mucosal epithelium of the small intestine, as well as changes in intestinal motility. The obtained results suggest a central role for iota toxin in the pathogenesis of C. perfringens type E hemorrhagic enteritis, and contribute to remark the importance of clostridial binary toxins in digestive diseases. Published by Elsevier Ltd.

  8. Effects of Clostridium perfringens alpha and epsilon toxins in the bovine gut.

    Science.gov (United States)

    Morris, Winston E; Dunleavy, Mariana V; Diodati, Julián; Berra, Guillermo; Fernandez-Miyakawa, Mariano E

    2012-02-01

    Clostridium perfringens alpha and epsilon toxins produce enterotoxaemia in sheep and goats. However, the information regarding the pathophysiology of alpha and epsilon toxins in the bovine intestine is still scanty. In this study, intestinal loops were performed in the ileum and colon of three one-week-old Holstein and two four-week-old crossbreed calves. Laparotomy was performed in all calves under anaesthesia and four loops -three cm long- were performed in the small and large intestines. For both intestines, loops were inoculated with alpha or epsilon toxins. Tissue samples from all loops were obtained and processed for routine histology and for transmission electron microscopy. Congestion was observed in toxin treated loops. Fluid accumulation in the gut lumen was prominent in all treated loops, but in epsilon treated ones the mucous was also haemorrhagic. The histology revealed large amount of exfoliated epithelial cells in the lumen of alpha toxin treated loops and severe haemorrhage was observed in the lamina propria of epsilon toxin treated colonic loops. Despite some necrotic exfoliated enterocytes, no ultraestructural changes were observed in alpha toxin treated loops, though with epsilon toxin the loops exhibited dilation of the intercellular space in the mucosa of both, small and large intestines. These observations indicate that both, alpha and epsilon toxins can alter the intestinal barrier, in calves and are pathogenic for this species. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. CD44 Promotes intoxication by the clostridial iota-family toxins.

    Directory of Open Access Journals (Sweden)

    Darran J Wigelsworth

    Full Text Available Various pathogenic clostridia produce binary protein toxins associated with enteric diseases of humans and animals. Separate binding/translocation (B components bind to a protein receptor on the cell surface, assemble with enzymatic (A component(s, and mediate endocytosis of the toxin complex. Ultimately there is translocation of A component(s from acidified endosomes into the cytosol, leading to destruction of the actin cytoskeleton. Our results revealed that CD44, a multifunctional surface protein of mammalian cells, facilitates intoxication by the iota family of clostridial binary toxins. Specific antibody against CD44 inhibited cytotoxicity of the prototypical Clostridium perfringens iota toxin. Versus CD44(+ melanoma cells, those lacking CD44 bound less toxin and were dose-dependently resistant to C. perfringens iota, as well as Clostridium difficile and Clostridium spiroforme iota-like, toxins. Purified CD44 specifically interacted in vitro with iota and iota-like, but not related Clostridium botulinum C2, toxins. Furthermore, CD44 knockout mice were resistant to iota toxin lethality. Collective data reveal an important role for CD44 during intoxication by a family of clostridial binary toxins.

  10. Tetanus toxin in dissociated spinal cord cultures: long-term characterization of form and action.

    Science.gov (United States)

    Habig, W H; Bigalke, H; Bergey, G K; Neale, E A; Hardegree, M C; Nelson, P G

    1986-09-01

    The clinical course of tetanus is notable, in addition to its often dramatic clinical presentation, by the long duration of the neuromuscular symptoms. Survivors may have tetanic manifestations for several weeks after the onset of the disease. In this article we correlate the duration of specific electrophysiologic effects produced by tetanus toxin with the degradation of cell-associated toxin in primary cultures of mouse spinal cord neurons. From these studies we can conclude that the toxin has a half-life of 5-6 days. Both the heavy and the light chains of tetanus toxin degrade at similar rates. Labeled toxin, visualized by radioautography, is associated with neuronal cell bodies and neurites, and its distribution is not altered during a 1-week period following toxin exposure. Blockade of synaptic activity persists for weeks at the concentration of radiolabeled toxin used in these studies. This blockade of transmission is reversed as the toxin is degraded, suggesting that degradation of toxin may be a sufficient mechanism for recovery from tetanus.

  11. The role of transglutaminase in the mechanism of action of tetanus toxin.

    Science.gov (United States)

    Coffield, J A; Considine, R V; Jeyapaul, J; Maksymowych, A B; Zhang, R D; Simpson, L L

    1994-09-30

    Tetanus toxin is a zinc-dependent metalloendoprotease that cleaves synaptobrevin, a polypeptide found in the membranes of synaptic vesicles. This action is thought to account for toxin-induced blockade of transmitter release. However, Facchiano and Luini (Fachiano, F., and Luini, A. (1992) J. Biol Chem. 267, 13267-13271) have proposed that tetanus toxin can stimulate transglutaminase, and Facchiano et al. (Facchiano, F., Benfenati, F., Valtorta, F., and Luini, A. (1993) J. Biol Chem. 268, 4588-4591) have further proposed that the stimulated enzyme produces cross-linking of synapsin. These actions might also account for toxin-induced blockade of exocytosis. Therefore, a series of experiments were performed to evaluate the possibility that tetanus toxin exerts its effects via transglutaminase. The results indicated that clostridial neurotoxins were poor substrates for the cross-linking effects of transglutaminase, and transglutaminase was a poor substrate for the proteolytic actions of tetanus toxin. In addition, at concentrations relevant to blockade of exocytosis, clostridial neurotoxins did not act on intact cells to stimulate transglutaminase, nor did they act on the isolated enzyme to stimulate cross-linking of putrescine and dimethylcasein. When used as competitive inhibitors of endogenous transglutaminase substrates, glycine methyl ester and monodansylcadaverine did not block toxin action. Furthermore, concentrations of calcium that were too low to support transglutaminase activity did not prevent toxin action. The data suggest that stimulation of transglutaminase is not the principal mechanism by which tetanus toxin blocks exocytosis in nerve cells.

  12. Climate change impacts on natural toxins in food production systems, exemplified by deoxynivalenol in wheat and diarrhetic shellfish toxins

    DEFF Research Database (Denmark)

    van der Fels-Klerx, H J; Olesen, Jørgen E; Naustvoll, L-J

    2012-01-01

    on food safety hazards, rather than median or average values only. Furthermore, it is recommended to closely monitor levels of mycotoxins and marine biotoxins in the future, in particular related to risky situations associated with favourable climatic conditions for toxin producing organisms...

  13. Comparative analysis of antimicrobial activities of valinomycin and cereulide, the Bacillus cereus emetic toxin

    NARCIS (Netherlands)

    Tempelaars, M.H.; Rodrigues, S.; Abee, T.

    2011-01-01

    Cereulide and valinomycin are highly similar cyclic dodecadepsipeptides with potassium ionophoric properties. Cereulide, produced by members of the Bacillus cereus group, is known mostly as emetic toxin, and no ecological function has been assigned. A comparative analysis of the antimicrobial

  14. Insights into the genetics and molecular mechanisms of pink bollworm resistance to Cry toxins

    Science.gov (United States)

    Transgenic crops producing Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) toxins target key insect pests in cotton and corn cropping systems. The pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), is currently the target of an area-wide eradication progra...

  15. Bothrops jararaca venom gland secretory cells in culture: Effects of noradrenaline on toxin production and secretion.

    Science.gov (United States)

    Viana, Luciana Godoy; Valente, Richard Hemmi; Heluany, Cíntia Scucuglia; Souza-Imberg, Andreia; Luna, Milene Schmidt; Perales, Jonas; Yamanouye, Norma

    2017-07-01

    Primary culture of snake venom gland secretory cells could be a good model to study the mechanism(s) of toxin(s) production. These cells can produce and secrete venom to the medium with a hemorrhagic activity comparable to that induced by venom collected from snakes. Production of new venom is triggered by the sympathetic outflow, through the release of noradrenaline, but the importance of this neurotransmitter on toxin synthesis has not been addressed. This work led to the identification and comparison of the toxin panel produced by cultured secretory cells, during a 12-day time-course analysis, as well as to the effects of noradrenaline on the process. The results showed that in our culture model the synthesis of new toxins is asynchronous, mimicking data previously published from proteomic analyses of venom glands harvested from animal experimentation. Furthermore, noradrenaline did regulate the synthesis and/or secretion of venom toxins over the analyzed period. Finally, we demonstrated that snake venom metalloproteinases present in these cultured cells secretome were mostly in their zymogen forms; consequently, processing occurs after secretion to the gland lumen. Overall, the data support the use of venom gland secretory cells as a reliable model to investigate the mechanism(s) of toxin(s) synthesis and secretion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Influence of yogurt fermentation and refrigerated storage on the stability of protein toxin contaminants.

    Science.gov (United States)

    Jackson, Lauren S; Triplett, Odbert A; Tolleson, William H

    2015-06-01

    Dairy products sold in a ready-to-eat form present the risk that adulterants persisting through manufacturing, storage, and distribution would reach consumers. Pathogenic microbes, including shigatoxigenic strains of Escherichia coli and the toxins they produce, are common food safety hazards associated with dairy products. Ricin and abrin are plant-derived ribosome-inactivating protein toxins related to the shiga-like toxins produced by E. coli. Limited information exists on the effects of manufacturing processes on the stabilities of these heat-resistant ribosome-inactivating proteins in the presence of foods. The goal of this study was to determine how typical yogurt manufacturing and storage processes influence ribosome-inactivating protein toxins. Ricin and abrin were added to skim or whole milk and batch pasteurized. Complete inactivation of both toxins was observed after 30 minutes at 85 °C. If the toxins were added after pasteurization, the levels of ricin and abrin in yogurt and their cytotoxic activities did not change significantly during fermentation or refrigerated storage for 4 weeks. The activities of ricin and abrin were inhibited by skim milk, nonfat yogurt, whole milk, and whole milk yogurt. The results showed minimal effects of the toxins on yogurt pH and %titratable acidity but inhibitory effects of yogurt on toxin activity. Published by Elsevier Ltd.

  17. Targeted toxins in brain tumor therapy.

    Science.gov (United States)

    Li, Yan Michael; Hall, Walter A

    2010-11-01

    Targeted toxins, also known as immunotoxins or cytotoxins, are recombinant molecules that specifically bind to cell surface receptors that are overexpressed in cancer and the toxin component kills the cell. These recombinant proteins consist of a specific antibody or ligand coupled to a protein toxin. The targeted toxins bind to a surface antigen or receptor overexpressed in tumors, such as the epidermal growth factor receptor or interleukin-13 receptor. The toxin part of the molecule in all clinically used toxins is modified from bacterial or plant toxins, fused to an antibody or carrier ligand. Targeted toxins are very effective against cancer cells resistant to radiation and chemotherapy. They are far more potent than any known chemotherapy drug. Targeted toxins have shown an acceptable profile of toxicity and safety in early clinical studies and have demonstrated evidence of a tumor response. Currently, clinical trials with some targeted toxins are complete and the final results are pending. This review summarizes the characteristics of targeted toxins and the key findings of the important clinical studies with targeted toxins in malignant brain tumor patients. Obstacles to successful treatment of malignant brain tumors include poor penetration into tumor masses, the immune response to the toxin component and cancer heterogeneity. Strategies to overcome these limitations are being pursued in the current generation of targeted toxins.

  18. Inositol hexakisphosphate-dependent processing of Clostridium sordellii lethal toxin and Clostridium novyi alpha-toxin.

    Science.gov (United States)

    Guttenberg, Gregor; Papatheodorou, Panagiotis; Genisyuerek, Selda; Lü, Wei; Jank, Thomas; Einsle, Oliver; Aktories, Klaus

    2011-04-29

    Clostridium sordellii lethal toxin and Clostridium novyi α-toxin, which are virulence factors involved in the toxic shock and gas gangrene syndromes, are members of the family of clostridial glucosylating toxins. The toxins inactivate Rho/Ras proteins by glucosylation or attachment of GlcNAc (α-toxin). Here, we studied the activation of the autoproteolytic processing of the toxins by inositol hexakisphosphate (InsP(6)) and compared it with the processing of Clostridium difficile toxin B. In the presence of low concentrations of InsP(6) (<1 μM), toxin fragments consisting of the N-terminal glucosyltransferase (or GlcNAc-transferase) domains and the cysteine protease domains (CPDs) of C. sordellii lethal toxin, C. novyi α-toxin, and C. difficile toxin B were autocatalytically processed. The cleavage sites of lethal toxin (Leu-543) and α-toxin (Leu-548) and the catalytic cysteine residues (Cys-698 of lethal toxin and Cys-707 of α-toxin) were identified. Affinity of the CPDs for binding InsP(6) was determined by isothermal titration calorimetry. In contrast to full-length toxin B and α-toxin, autocatalytic cleavage and InsP(6) binding of full-length lethal toxin depended on low pH (pH 5) conditions. The data indicate that C. sordellii lethal toxin and C. novyi α-toxin are InsP(6)-dependently processed. However, full-length lethal toxin, but not its short toxin fragments consisting of the glucosyltransferase domain and the CPD, requires a pH-sensitive conformational change to allow binding of InsP(6) and subsequent processing of the toxin.

  19. Inositol Hexakisphosphate-dependent Processing of Clostridium sordellii Lethal Toxin and Clostridium novyi α-Toxin*

    Science.gov (United States)

    Guttenberg, Gregor; Papatheodorou, Panagiotis; Genisyuerek, Selda; Lü, Wei; Jank, Thomas; Einsle, Oliver; Aktories, Klaus

    2011-01-01

    Clostridium sordellii lethal toxin and Clostridium novyi α-toxin, which are virulence factors involved in the toxic shock and gas gangrene syndromes, are members of the family of clostridial glucosylating toxins. The toxins inactivate Rho/Ras proteins by glucosylation or attachment of GlcNAc (α-toxin). Here, we studied the activation of the autoproteolytic processing of the toxins by inositol hexakisphosphate (InsP6) and compared it with the processing of Clostridium difficile toxin B. In the presence of low concentrations of InsP6 (<1 μm), toxin fragments consisting of the N-terminal glucosyltransferase (or GlcNAc-transferase) domains and the cysteine protease domains (CPDs) of C. sordellii lethal toxin, C. novyi α-toxin, and C. difficile toxin B were autocatalytically processed. The cleavage sites of lethal toxin (Leu-543) and α-toxin (Leu-548) and the catalytic cysteine residues (Cys-698 of lethal toxin and Cys-707 of α-toxin) were identified. Affinity of the CPDs for binding InsP6 was determined by isothermal titration calorimetry. In contrast to full-length toxin B and α-toxin, autocatalytic cleavage and InsP6 binding of full-length lethal toxin depended on low pH (pH 5) conditions. The data indicate that C. sordellii lethal toxin and C. novyi α-toxin are InsP6-dependently processed. However, full-length lethal toxin, but not its short toxin fragments consisting of the glucosyltransferase domain and the CPD, requires a pH-sensitive conformational change to allow binding of InsP6 and subsequent processing of the toxin. PMID:21385871

  20. Application of Botulinum toxin Type A: An arsenal in dentistry

    Directory of Open Access Journals (Sweden)

    Lakshmana B Rao

    2011-01-01

    Full Text Available An extremely effective way of preventing damage to and enhancing treatment of dental hard tissues and restorations would be to ′′de-programme′′ the muscles responsible for excessive destructive forces and other gnathological-related diseases. The new paradigm is the intramuscular injection of Botulinum toxin type A (BOTOX into the affected muscles. It is a natural protein produced by anaerobic bacterium, Clostridium botulinum. The toxin inhibits the release of acetylcholine (ACH, a neurotransmitter responsible for the activation of muscle contraction and glandular secretion, and its administration results in reduction of tone in the injected muscle. There are seven distinct serotypes of Botulinum toxin, viz., A, B, C, D, E, F, and G, which differ in their potency, duration of action, and cellular target sites. This paper describes the different applications of BOTOX in dentistry.

  1. Application of Botulinum toxin type A: an arsenal in dentistry.

    Science.gov (United States)

    Rao, Lakshmana B; Sangur, Rajashekar; Pradeep, S

    2011-01-01

    An extremely effective way of preventing damage to and enhancing treatment of dental hard tissues and restorations would be to ''de-programme'' the muscles responsible for excessive destructive forces and other gnathological-related diseases. The new paradigm is the intramuscular injection of Botulinum toxin type A (BOTOX) into the affected muscles. It is a natural protein produced by anaerobic bacterium, Clostridium botulinum. The toxin inhibits the release of acetylcholine (ACH), a neurotransmitter responsible for the activation of muscle contraction and glandular secretion, and its administration results in reduction of tone in the injected muscle. There are seven distinct serotypes of Botulinum toxin, viz., A, B, C, D, E, F, and G, which differ in their potency, duration of action, and cellular target sites. This paper describes the different applications of BOTOX in dentistry.

  2. Rho-modifying bacterial protein toxins from Photorhabdus species.

    Science.gov (United States)

    Jank, Thomas; Lang, Alexander E; Aktories, Klaus

    2016-06-15

    Photorhabdus bacteria live in symbiosis with entomopathogenic nematodes. The nematodes invade insect larvae, where they release the bacteria, which then produce toxins to kill the insects. Recently, the molecular mechanisms of some toxins from Photorhabdus luminescens and asymbiotica have been elucidated, showing that GTP-binding proteins of the Rho family are targets. The tripartite Tc toxin PTC5 from P. luminescens activates Rho proteins by ADP-ribosylation of a glutamine residue, which is involved in GTP hydrolysis, while PaTox from Photorhabdus asymbiotica inhibits the activity of GTPases by N-acetyl-glucosaminylation at tyrosine residues and activates Rho proteins indirectly by deamidation of heterotrimeric G proteins. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Hijacking mitochondria: bacterial toxins that modulate mitochondrial function.

    Science.gov (United States)

    Jiang, Jhih-Hang; Tong, Janette; Gabriel, Kipros

    2012-05-01

    Bacterial infection has enormous global social and economic impacts stemming from effects on human health and agriculture. Although there are still many unanswered questions, decades of research has uncovered many of the pathogenic mechanisms at play. It is now clear that bacterial pathogens produce a plethora of proteins known as "toxins" and "effectors" that target a variety of physiological host processes during the course of infection. One of the targets of host targeted bacterial toxins and effectors are the mitochondria. The mitochondrial organelles are major players in many biological functions, including energy conversion to ATP and cell death pathways, which inherently makes them targets for bacterial proteins. We present a summary of the toxins targeted to mitochondria and for those that have been studied in finer detail, we also summarize what we know about the mechanisms of targeting and finally their action at the organelle. Copyright © 2012 Wiley Periodicals, Inc.

  4. Toxin-Induced Experimental Models of Learning and Memory Impairment.

    Science.gov (United States)

    More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

    2016-09-01

    Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson's disease dementia and Alzheimer's disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.

  5. Toxin-Induced Experimental Models of Learning and Memory Impairment

    Directory of Open Access Journals (Sweden)

    Sandeep Vasant More

    2016-09-01

    Full Text Available Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson’s disease dementia and Alzheimer’s disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.

  6. Removal of Cholera Toxin from Aqueous Solution by Probiotic Bacteria

    Directory of Open Access Journals (Sweden)

    Jussi A. O. Meriluoto

    2012-06-01

    Full Text Available Cholera remains a serious health problem, especially in developing countries where basic hygiene standards are not met. The symptoms of cholera are caused by cholera toxin, an enterotoxin, which is produced by the bacterium Vibrio cholerae. We have recently shown that human probiotic bacteria are capable of removing cyanobacterial toxins from aqueous solutions. In the present study we investigate the ability of the human probiotic bacteria, Lactobacillus rhamnosus strain GG (ATCC 53103 and Bifidobacterium longum 46 (DSM 14583, to remove cholera toxin from solution in vitro. Lactobacillus rhamnosus strain GG and Bifidobacterium longum 46 were able to remove 68% and 59% of cholera toxin from aqueous solutions during 18 h of incubation at 37 °C, respectively. The effect was dependent on bacterial concentration and L. rhamnosus GG was more effective at lower bacterial concentrations. No significant effect on cholera toxin concentration was observed when nonviable bacteria or bacterial supernatant was used.

  7. Alpha-Toxin Promotes Mucosal Biofilm Formation by Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Michele J Anderson

    2012-05-01

    Full Text Available Staphylococcus aureus causes numerous diseases in humans ranging from the mild skin infections to serious, life-threatening, superantigen-mediated Toxic Shock Syndrome (TSS. S. aureus may also be asymptomatically carried in the anterior nares, vagina or on the skin, which serve as reservoirs for infection. Pulsed-field gel electrophoresis clonal type USA200 is the most widely disseminated colonizer and a major cause of TSS. Our prior studies indicated that α-toxin was a major epithelial proinflammatory exotoxin produced by TSS S. aureus USA200 isolates. It also facilitated the penetration of TSS Toxin-1 (TSST-1 across vaginal mucosa. However, the majority of menstrual TSS isolates produce low α-toxin due to a nonsense point mutation at codon 113, designated hly, suggesting mucosal adaptation. The aim of this study was to characterize the differences between TSS USA200 strains [high (hla+ and low (hly+ α-toxin producers] in their abilities to infect and disrupt vaginal mucosal tissue. A mucosal model was developed using ex vivo porcine vaginal mucosa, LIVE/DEAD® staining and confocal microscropy to characterize biofilm formation and tissue viability of TSS USA 200 isolates CDC587 and MN8, which contain the α-toxin pseudogene (hly, MNPE (hla+ and MNPE isogenic hla knockout (hlaKO. All TSS strains grew to similar bacterial densities (1-5 x 108 CFU on the mucosa and were proinflammatory over 3 days. However, MNPE formed biofilms with significant reductions in the mucosal viability whereas neither CDC587, MN8 (hly+, or MNPE hlaKO, formed biofilms and were less cytotoxic. The addition of exogenous, purified α-toxin to MNPE hlaKO restored the biofilm phenotype. Our studies suggest α-toxin affects S. aureus phenotypic growth on vaginal mucosa, by promoting tissue disruption and biofilm formation; and α–toxin mutants (hly are not benign colonizers, but rather form a different type of infection, which we have termed high density pathogenic

  8. A new Cry toxin with a unique two-component dependency from Bacillus sphaericus.

    Science.gov (United States)

    Jones, Gareth W; Nielsen-Leroux, Christina; Yang, Yankun; Yuan, Zhiming; Dumas, Vinícius Fiúza; Monnerat, Rose Gomes; Berry, Colin

    2007-12-01

    Highly pathogenic strains of Bacillus sphaericus produce the mosquitocidal Bin proteins, but resistance to this toxin can be produced under laboratory and field conditions. Analysis of strains able to overcome this resistance revealed the presence of a previously undescribed type of two-component toxin. One subunit, Cry48Aa1, is related to the 3-domain crystal toxins of Bacillus thuringiensis. Uniquely for this type of protein, insect toxicity is only achieved in the presence of a second, accessory protein, Cry49Aa1. This protein is itself related to both the binary toxin of B. sphaericus and to Cry35 and Cry36 of B. thuringiensis, none of which require interaction with Cry48Aa1-like proteins for their activity. The necessity for both Cry48Aa1 and Cry49Aa1 components for pathogenicity, therefore, indicates an unprecedented interaction to generate toxicity. Despite high potency for purified Cry48Aa1/Cry49Aa1 proteins (LC50 for third instar Culex quinquefasciatus larvae: 15.9 ng/ml and 6.3 ng/ml respectively), bacteria producing them show suboptimal mosquitocidal activity due to low-level Cry48Aa1 production. This new toxin combination may indicate a fortuitous combination of members of the gene families that encode 3-domain Cry toxins and Binary-like toxins, permitting the "mix-and-match" evolution of a new component in the mosquitocidal armoury.

  9. Development and Evaluation of Monoclonal Antibodies for the Glucoside of T-2 Toxin (T2-Glc

    Directory of Open Access Journals (Sweden)

    Susan McCormick

    2013-07-01

    Full Text Available The interactions between fungi and plants can yield metabolites that are toxic in animal systems. Certain fungi are known to produce sesquiterpenoid trichothecenes, such as T-2 toxin, that are biotransformed by several mechanisms including glucosylation. The glucosylated forms have been found in grain and are of interest as potential reservoirs of T-2 toxin that are not detected by many analytical methods. Hence the glucosides of trichothecenes are often termed “masked” mycotoxins. The glucoside of T-2 toxin (T2-Glc was linked to keyhole limpet hemocyanin and used to produce antibodies in mice. Ten monoclonal antibody (Mab-producing hybridoma cell lines were developed. The Mabs were used in immunoassays to detect T2-Glc and T-2 toxin, with midpoints of inhibition curves (IC50s in the low ng/mL range. Most of the Mabs demonstrated good cross-reactivity to T-2 toxin, with lower recognition of HT-2 toxin. One of the clones (2-13 was further characterized with in-depth cross-reactivity and solvent tolerance studies. Results suggest Mab 2-13 will be useful for the simultaneous detection of T-2 toxin and T2-Glc.

  10. The Typhoid Toxin Promotes Host Survival and the Establishment of a Persistent Asymptomatic Infection

    DEFF Research Database (Denmark)

    Del Bel Belluz, Lisa; Guidi, Riccardo; Pateras, Ioannis S.

    2016-01-01

    analysis confirmed the toxin-mediated suppression of the intestinal inflammatory response. The presence of a functional typhoid toxin further induced an increased frequency of asymptomatic carriers. Our data indicate that the typhoid toxin DNA damaging activity increases host survival and favours long......Bacterial genotoxins, produced by several Gram-negative bacteria, induce DNA damage in the target cells. While the responses induced in the host cells have been extensively studied in vitro, the role of these effectors during the course of infection remains poorly characterized. To address...... this issue, we assessed the effects of the Salmonella enterica genotoxin, known as typhoid toxin, in in vivo models of murine infection. Immunocompetent mice were infected with isogenic S. enterica, serovar Typhimurium (S. Typhimurium) strains, encoding either a functional or an inactive typhoid toxin...

  11. Quantitative Mass Spectrometric Analysis and Post-Extraction Stability Assessment of the Euglenoid Toxin Euglenophycin

    Directory of Open Access Journals (Sweden)

    Paul V. Zimba

    2013-09-01

    Full Text Available Euglenophycin is a recently discovered toxin produced by at least one species of euglenoid algae. The toxin has been responsible for several fish mortality events. To facilitate the identification and monitoring of euglenophycin in freshwater ponds, we have developed a specific mass spectrometric method for the identification and quantitation of euglenophycin. The post-extraction stability of the toxin was assessed under various conditions. Euglenophycin was most stable at room temperature. At 8 °C there was a small, but statistically significant, loss in toxin after one day. These methods and knowledge of the toxin’s stability will facilitate identification of the toxin as a causative agent in fish kills and determination of the toxin’s distribution in the organs of exposed fish.

  12. Shiga Toxins: Intracellular Trafficking to the ER Leading to Activation of Host Cell Stress Responses

    Directory of Open Access Journals (Sweden)

    Moo-Seung Lee

    2010-06-01

    Full Text Available Despite efforts to improve hygenic conditions and regulate food and dr