scholarly journals Baicalein Inhibits Stx1 and 2 of EHE: Effects of Baicalein on the Cytotoxicity, Production, and Secretion of Shiga Toxins of Enterohaemorrhagic Escherichia coli

Toxins ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 505 ◽  
Author(s):  
Vinh ◽  
Shinohara ◽  
Yamada ◽  
Duc ◽  
Nakayama ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Antibacterial Agent ◽  
Foodborne Pathogen ◽  
Vero Cells ◽  
In Silico Screening ◽  
Shiga Toxins ◽  
Enterohaemorrhagic Escherichia Coli ◽  
Compound Database ◽  
Real Time Qpcr

Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is an important foodborne pathogen. Baicalein (5,6,7-trihydroxylflavone), a flavone isolated from the roots of Scutellaria baicalensis, is considered as a potential antibacterial agent to control foodborne pathogens. Among seven compounds selected by in silico screening of the natural compound database, baicalein inhibited the cytotoxicity of both Shiga toxins 1 and 2 (Stx1 and Stx2) against Vero cells after pretreatment at 0.13 mmol/L. In addition, baicalein reduced the susceptibility of Vero cells to both Stx1 and Stx2. Real-time qPCR showed that baicalein increased transcription of stx1 but not of stx2. However, baicalein had no effects on production or secretion of Stx1 or Stx2. Docking models suggested that baicalein formed a stable structure with StxB pentamer with low intramolecular energy. The results demonstrate that inhibitory activity of baicalein against the cytotoxicity of both Stx1 and Stx2 might be due to of the formation of a binding structure inside the pocket of the Stx1B and Stx2B pentamers.

Rapid and accurate detection of Escherichia coli O157:H7 in beef using microfluidic wax-printed paper-based ELISA

The Analyst ◽  
2020 ◽  
Vol 145 (8) ◽  
pp. 3106-3115 ◽  
Author(s):  
Yanan Zhao ◽  
Dexin Zeng ◽  
Chao Yan ◽  
Wei Chen ◽  
Jianluan Ren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Point Of Care ◽  
Foodborne Pathogen ◽  
Escherichia Coli O157 ◽  
Good Sensitivity ◽  
Point Of Care Testing ◽  
Accurate Detection ◽  
New Ideas ◽  
Sensitivity Specificity

Escherichia coli O157:H7 is a severe foodborne pathogen. Paper-based ELISA can rapidly and accurately detect E.coli O157:H7 in beef. The method has good sensitivity, specificity and repeatability. It is suitable for point-of-care testing and offers new ideas for the detection of other foodborne pathogens.

Effect of Preservatives on Shiga Toxigenic Phages and Shiga Toxin of Escherichia coli O157:H7

2012 ◽  
Vol 75 (5) ◽  
pp. 959-965 ◽  
Author(s):  
TOMÁS SUBILS ◽  
VIRGINIA AQUILI ◽  
GUILLERMO EBNER ◽  
CLAUDIA BALAGUÉ
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Sodium Benzoate ◽  
Vero Cells ◽  
Lytic Activity ◽  
Potassium Sorbate ◽  
Lambda Phage ◽  
Sodium Propionate ◽  
Food Preservatives ◽  
Shiga Toxins

Toxin synthesis by Shiga toxin–producing Escherichia coli (STEC) appears to be coregulated through the induction of the integrated bacteriophages that encode the toxin genes. These phages might be the principal means for the dissemination and release of Shiga toxins. We evaluated the effect of three common food preservatives, potassium sorbate, sodium benzoate, and sodium propionate, on the propagation of the phages and Shiga toxins. We tested each preservative at four concentrations, 1, 1.25, 2.5, and 5 mg/ml, both on free phages and on lysogenic phages in bacteria. We also evaluated the expression of a lambdoid phage, which was exposed to increasing concentrations of preservatives, by measuring β-galactosidase activity from SPC105, a transductant strain. Furthermore, we tested the effect of the preservatives on cytotoxigenic activity of Shiga toxin on Vero cells. We detected an increase of the inhibitory effect of the phage lytic activity, both in lysogenic and free phages, as the preservative concentration increased. However, the inhibition was higher on the lysogenic phages release than on free phages. Sodium benzoate and potassium sorbate were about equal at inhibiting phages; they were more effective than sodium propionate. A significant decrease of lacZ expression, encoded in a lambda phage, was observed. We also found a reduction in Shiga toxin titer caused by exposure of E. coli O157:H7 to 5 mg/ml sodium benzoate or potassium sorbate. These results imply that these three preservatives, used to inhibit microbial spoilage of foods, also act to inhibit lytic activity and dispersion of a phage carrying the gene encoding powerful Shiga cytotoxins. Also notable was the inactivation of Shiga toxin activity, although this effect was detected using concentrations of preservatives greater than those allowed by the Argentine Food Code.

scholarly journals Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model

2015 ◽  
Vol 83 (11) ◽  
pp. 4185-4193 ◽  
Author(s):  
Kakolie Goswami ◽  
Chun Chen ◽  
Lingzi Xiaoli ◽  
Kathryn A. Eaton ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogen ◽  
Toxin Production ◽  
Coli Strain ◽  
Content Type ◽  
Infectious Dose ◽  
Shiga Toxins ◽  
E Coli ◽  
Nonpathogenic Strain ◽  
Uremic Syndrome

ABSTRACTEscherichia coliO157:H7 is a notorious foodborne pathogen due to its low infectious dose and the disease symptoms it causes, which include bloody diarrhea and severe abdominal cramps. In some cases, the disease progresses to hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), due to the expression of one or more Shiga toxins (Stx). Isoforms of Stx, including Stx2a, are encoded within temperate prophages. In the presence of certain antibiotics, phage induction occurs, which also increases the expression of toxin genes. Additionally, increased Stx2 accumulation has been reported when O157:H7 was cocultured with phage-susceptible nonpathogenicE. coli. This study characterized anE. coliO157:H7 strain, designated PA2, that belongs to the hypervirulent clade 8 cluster. Stx2a levels after ciprofloxacin induction were lower for PA2 than for the prototypical outbreak strains Sakai and EDL933. However, during coculture with the nonpathogenic strainE. coliC600, PA2 produced Stx2a levels that were 2- to 12-fold higher than those observed during coculture with EDL933 and Sakai, respectively. Germfree mice cocolonized by PA2 and C600 showed greater kidney damage, increased Stx2a accumulation in feces, and more visible signs of disease than mice given PA2 or C600 alone. These data suggest one mechanism by which microorganisms associated with the colonic microbiota could enhance the virulence ofE. coliO157:H7, particularly a subset of clade 8 strains.

Escherichia coli O157:H7 Populations in Sheep Can Be Reduced by Chlorate Supplementation†

2003 ◽  
Vol 66 (2) ◽  
pp. 194-199 ◽  
Author(s):  
T. R. CALLAWAY ◽  
T. S. EDRINGTON ◽  
R. C. ANDERSON ◽  
K. J. GENOVESE ◽  
T. L. POOLE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Foodborne Pathogens ◽  
Intestinal Tract ◽  
Foodborne Pathogen ◽  
Escherichia Coli O157 ◽  
Foodborne Illnesses ◽  
Fatty Acid Production ◽  
E Coli ◽  
Ruminant Animals

Ruminant animals are a natural reservoir of the foodborne pathogen Escherichia coli O157:H7. Some foodborne pathogens (e.g., E. coli) are equipped with a nitrate reductase that cometabolically reduces chlorate. The intracellular reduction of chlorate to chlorite kills nitrate reductase–positive bacteria; however, species that do not reduce nitrate are not affected by chlorate. Therefore, it has been suggested that ruminants be supplemented with chlorate prior to shipment for slaughter in order to reduce foodborne illnesses in human consumers. Sheep (n = 14) were fed a high-grain ration and were experimentally infected with E. coli O157:H7. These sheep were given an experimental product (XCP) containing the equivalent of either 2.5 mM NaNO3 and 100 mM NaCl (control sheep; n = 7) or 2.5 mM NaNO3 and 100 mM NaClO3 (chlorate [XCP]–treated sheep; n = 7). Control and XCP-treated sheep were treated for 24 h; XCP treatment reduced the population of inoculated E. coli O157:H7 (P < 0.05) from 102, 105, and 105 CFU/g in the rumen, cecum, and rectum, respectively, to <101 CFU/g in all three sections of the gastrointestinal tract. The number of sheep testing positive for E. coli O157:H7 was significantly reduced by XCP treatment. In a similar fashion, total E. coli and coliforms were also reduced (P < 0.05) in all three compartments of the intestinal tract. Intestinal pH, total volatile fatty acid production, and the acetate/propionate ratio were unaffected by XCP treatment. On the basis of these results, it appears that chlorate treatment can be an effective method for the reduction of E. coli O157:H7 populations in ruminant animals immediately prior to slaughter.

Shiga Toxin–Producing Escherichia coli in Beef Heifers Grazing an Irrigated Pasture

2001 ◽  
Vol 64 (10) ◽  
pp. 1613-1616 ◽  
Author(s):  
B. H. THRAN ◽  
H. S. HUSSEIN ◽  
M. R. HALL ◽  
S. F. KHAIBOULLINA
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Shiga Toxin ◽  
Vero Cells ◽  
Control Measures ◽  
Fecal Samples ◽  
E Coli ◽  
Microbiological Testing ◽  
Angus Heifers ◽  
Postharvest Control

Shiga toxin–producing Escherichia coli (STEC) produce toxins that have been associated with several human illnesses. E. coli O157:H7 is the most well-studied STEC and was first associated with consumption of improperly cooked ground beef in 1982. E. coli O157:H7 is not the only foodborne STEC because other STEC serotypes are also associated with human illnesses. The objective of this study was to assess prevalence of STEC in 23 yearling beef (Angus) heifers grazing an irrigated grass pasture in spring (April), summer (July), fall (October), and winter (December) of 1999. A total of 86 fecal samples were rectally collected and were subjected to microbiological testing for the presence of STEC. Nine E. coli isolates from five heifers (one in spring and fall and three in winter) were toxic to Vero cells. Of these isolates, four were E. coli O157:H7, two belonged to the serogroup O6, one O39:NM, one O113:H−, and the final isolate was untypable. The STEC prevalence rate in our herd ranged from 4% (spring) to 15% (winter). Based on detecting both O157:H7 and non-O157:H7 STEC in our heifers, it is clear that screening fecal samples should not be limited to E. coli O157:H7. Identification of STEC-positive cattle prior to slaughter should help in reducing the risk of beef contamination with such foodborne pathogens if pre- and/or postharvest control measures are applied to such animals.

Antibacterial Activities of Sirih Merah (Piper crocatum) Leaf Extracts

2019 ◽  
Vol 5 (3) ◽  
pp. 1-10
Author(s):  
Puspa Julistia Puspita ◽  
Mega Safithri ◽  
Nirmala Peni Sugiharti
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Antibacterial Agent ◽  
Leaf Extract ◽  
Antibacterial Activities ◽  
Leaf Extracts ◽  
Herbal Plants

Piper crocatum is one of medicinal herbal plants with a large number of benefits. Usually herbal plants have activity as antibacterial agent. Therefore, the objectives of this research were to obtain information on antibacterial activities of the leaf extracts of Piper crocatum againts four types of bacteria, in that Staphylococcus, Bacillus substilis, Escherichia coli, and Pseudomonas aeruginosa and then to analyze the phytochemistry of the leaf extracts of Piper crocatum. The leaves of Piper crocatum were extracted by maceration and reflux using ethanol 30%. The assays of the antibacterial activities and phytochemistry on the extracts were carried out using the method of Maria Bintang. Results showed that the yield of the extraction using ethanol by maceration method was 20.8%. Meanwhile, using the reflux method, the yield was obtained about 26.25%. The phytochemistry analysis showed that the leaf extracts of Piper crocatum contained alkaloid, steroid and tanin. According to this study, it was found that the leaf extract of Piper crocatum can be used to inhibit the growth of B. subtilis and P. aeuruginosa, but can not inhibit the growth of E.coli and S. aureus.

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