scholarly journals Characterization of virulence factors in Escherichia coli isolated from diarrheic and healthy calves in Austria shedding various enteropathogenic agents

2009 ◽  
Vol 54 (No. 1) ◽  
pp. 1-11 ◽  
Author(s):  
C. Herrera-Luna ◽  
D. Klein ◽  
G. Lapan ◽  
S. Revilla-Fernandez ◽  
B. Haschek ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Clostridium Perfringens ◽  
Shiga Toxin ◽  
Systemic Disease ◽  
Toxin Gene ◽  
Detection Rates ◽  
E Coli ◽  
Faecal Samples ◽  
Control And Prevention

Faecal samples from 230 diarrhoeic and healthy calves aged 0–6 weeks, from 100 farms in Austria, were examined between October 2004 and February 2005 for the presence of bacteria, especially Shiga toxin-producing <I>Escherichia coli </I> (STEC), viruses and parasites. <I>Escherichia coli</I> was detected in 17% of all the faecal samples and was more prevalent in healthy calves. However, <I>E. coli</I> F5 was identified only in one calf without diarrhoea. Overall, 35 out of the 230 (15.2%) samples analyzed carried the Shiga toxin gene: <I>stx1, stx2</I> or both <I>stx1</I> and<I> stx2</I> in their faeces, STEC. Nevertheless, out of 39 pathogenic <I>E. coli</I> positive samples observed, only two carried the Shiga toxin genes: <I>stx1</I>, in a diarrhoeic calf and both <I>stx1</I> and <I>stx2</I> in a healthy calf. <I>eaeA</I> and <I>Ehly</I> genes were detected more frequently in the strains from diarrhoeic calves 57.1% and 50.0%, respectively. <I>Clostridium perfringens</I> was detected in twenty-one samples, the most prevalent toxin type of <I>Clostridium perfringens</I> was found to be type A (76.2%). Other bacteria such as <I>Klebsiella</I> spp. and <I>Proteus</I> spp. were present in 1.3% and 0.4% of all samples. <I>Salmonella</I> spp. was not detected. The detection rates of other enteropathogens were 25.7% bovine coronavirus, 11.7% <I>Cryptosporidium</I> spp., 10.4% <I>Eimeria</I> spp., 9.1% group A rotavirus and <I>Giardia</I> spp. 6.1%. We demonstrated the presence of the STEC virulence genes in healthy and diarrhoeic Austrian calves but the importance of the virulence factors of STEC (<I>stx1, stx2, eae</I> and <I>Ehly</I>) in calf diarrhoea and systemic disease is not well defined. Therefore, further studies are necessary to identify reservoirs or potential sources of virulent STEC strains in order to establish control and prevention strategies for STEC associated diseases in animals and humans.

scholarly journals Comparison between human and animal isolates of Shiga toxin-producing Escherichia coli O157 from Australia

2002 ◽  
Vol 128 (3) ◽  
pp. 357-362 ◽  
Author(s):  
N. FEGAN ◽  
P. DESMARCHELIER
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Human Infection ◽  
Pulsed Field Gel Electrophoresis ◽  
Toxin Gene ◽  
Escherichia Coli O157 ◽  
Animal Population ◽  
E Coli ◽  
Virulence Markers ◽  
Animal Isolates

There is very little human disease associated with enterohaemorrhagic Escherichia coli O157 in Australia even though these organisms are present in the animal population. A group of Australian isolates of E. coli O157:H7 and O157:H- from human and animal sources were tested for the presence of virulence markers and compared by XbaI DNA macrorestriction analysis using pulsed-field gel electrophoresis (PFGE). Each of 102 isolates tested contained the gene eae which encodes the E. coli attaching and effacing factor and all but one carried the enterohaemolysin gene, ehxA, found on the EHEC plasmid. The most common Shiga toxin gene carried was stx2c, either alone (16%) or in combination with stx1 (74%) or stx2 (3%). PFGE grouped the isolates based on H serotype and some clusters were source specific. Australian E. coli O157:H7 and H- isolates from human, animal and meat sources carry all the virulence markers associated with EHEC disease in humans therefore other factors must be responsible for the low rates of human infection in Australia.

scholarly journals Molecular analysis of Escherichia coli O157 strains isolated from cattle and pigs by the use of PCR and pulsed-field gel electrophoresis methods

2012 ◽  
Vol 47 (No. 6) ◽  
pp. 149-158 ◽  
Author(s):  
J. Osek ◽  
P. Gallien
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Genetic Relatedness ◽  
Rflp Analysis ◽  
Toxin Gene ◽  
Escherichia Coli O157 ◽  
Chromosomal Dna ◽  
E Coli ◽  
Shiga Toxin Genes ◽  
Porcine Origin

Fourteen Escherichia coli O157 strains isolated from cattle and pigs in Poland and in Germany were investigated, using PCR, for the genetic markers associated with Shiga toxin-producing E. coli (STEC). Only two strains, both of cattle origin, were positive for the fliC (H7) gene and could be classified as O157 : H7. Nine isolates had stx shiga toxin genes, either stx1 (1 strain), stx2 (4 isolates) or both (4 strains). The stx2-carrying samples were further subtyped by PCR for the stx2c, stx2d, and stx2e toxin variants. It was shown that all but one stx2-positive bacteria possessed the stx2c Shiga toxin gene type and one stx2 STEC isolate had the stx2d virulence factor sub-type. The eaeA (intimin) gene was found in 9 strains (8 isolates from cattle and one strain from pigs); all of them harboured the genetic marker characteristic of the gamma intimin variant. The translocated intimin receptor (tir) gene was detected in 7 isolates tested and among them only one tir-positive strain was recovered from pigs. The ehly E. coli enterohemolysin gene was amplified in all but one strains obtained from cattle and only in one isolate of porcine origin. The genetic relatedness of the analysed E. coli O157 strains was examined by restriction fragment length polymorphism (RFLP) of chromosomal DNA digested with XbaI. Two distinct but related RFLP pattern clusters were observed: one with 9 strains (8 isolates of bovine origin and one strain obtained from pigs) and the other one comprises the remaining 5 E. coli isolates (4 of porcine origin and one strain recovered from cattle). The results suggest that pigs, besides cattle, may be a reservoir of E. coli O157 strains potentially pathogenic to humans. Moreover, epidemiologically unrelated isolates of the O157 serogroup, recovered from different animal species, showed a clonal relationship as demonstrated by the RFLP analysis.

Detection of cytolethal distending toxin and other virulent factors in Escherichia coli samples from animal livestock, retail foods and gastroenteritis human cases in Qatar

2020 ◽  
Author(s):  
Adriana Morales Gómez ◽  
Nilda N. Valenzuela ◽  
Kenlyn E. Peters ◽  
Ahmed Salem ◽  
Ali Sultan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Food Products ◽  
Cross Sectional Study ◽  
Toxin Gene ◽  
Cytolethal Distending Toxin ◽  
Cross Sectional ◽  
E Coli ◽  
Polymerase Chain ◽  
Retail Food

Cytolethal distending toxin (CDT) is a heterotrimeric AB-type genotoxin produced by several clinically important bacterial pathogens. To better understand the risk of CDT within the food supply and human gastroenteritis patients in Qatar, we investigated the frequency of the CDT gene (cdtB) among Escherichia coli (E. coli) strains recovered from food products, animal livestock, and human gastroenteritis patients. In this cross-sectional study, E. coli isolates were screened for cdtB using polymerase chain reaction (PCR). cdtB positive strains were further examined for E. coli cdtB gene types (cdt I, cdt II, cdt III, cdt IV and cdtV), serotypes O157: H7, and non-O157 Shiga toxin-producing E. coli O26, O45, O103, O111, O121, and O145. Screening for other virulent factors, stx (Shiga toxin gene) and eae (gene that encodes intimin) genes were also performed. The cdtB gene was detected in E. coli isolates sourced from all three groups; animal livestock (17%), retail foods (8%), and human gastroenteritis patients (3%). Although the incidence of cdtB gene harboring E. coli is relatively low among gastroenteritis patients, there is still a risk of infection from animal reservoirs as well as retail food products. Among the three groups, E. coli isolates from humans had the lowest occurrence of cdtB, stx, eae, and O157: H7. Furthermore, we advise implementing monitoring at the food production and preparation level.

scholarly journals Shiga Toxin Gene Loss and Transfer In Vitro and In Vivo during Enterohemorrhagic Escherichia coli O26 Infection in Humans

2007 ◽  
Vol 73 (10) ◽  
pp. 3144-3150 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Robin Köck ◽  
Alexander Mellmann ◽  
Wenlan Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gene Loss ◽  
Pulsed Field Gel Electrophoresis ◽  
Enterohemorrhagic Escherichia Coli ◽  
Toxin Gene ◽  
Shiga Toxins ◽  
E Coli

ABSTRACT Escherichia coli serogroup O26 consists of enterohemorrhagic E. coli (EHEC) and atypical enteropathogenic E. coli (aEPEC). The former produces Shiga toxins (Stx), major determinants of EHEC pathogenicity, encoded by bacteriophages; the latter is Stx negative. We have isolated EHEC O26 from patient stools early in illness and aEPEC O26 from stools later in illness, and vice versa. Intrapatient EHEC and aEPEC isolates had quite similar pulsed-field gel electrophoresis (PFGE) patterns, suggesting that they might have arisen by conversion between the EHEC and aEPEC pathotypes during infection. To test this hypothesis, we asked whether EHEC O26 can lose stx genes and whether aEPEC O26 can be lysogenized with Stx-encoding phages from EHEC O26 in vitro. The stx 2 loss associated with the loss of Stx2-encoding phages occurred in 10% to 14% of colonies tested. Conversely, Stx2- and, to a lesser extent, Stx1-encoding bacteriophages from EHEC O26 lysogenized aEPEC O26 isolates, converting them to EHEC strains. In the lysogens and EHEC O26 donors, Stx2-converting bacteriophages integrated in yecE or wrbA. The loss and gain of Stx-converting bacteriophages diversifies PFGE patterns; this parallels findings of similar but not identical PFGE patterns in the intrapatient EHEC and aEPEC O26 isolates. EHEC O26 and aEPEC O26 thus exist as a dynamic system whose members undergo ephemeral interconversions via loss and gain of Stx-encoding phages to yield different pathotypes. The suggested occurrence of this process in the human intestine has diagnostic, clinical, epidemiological, and evolutionary implications.

scholarly journals Molecular Characterization of Shiga Toxin-Producing Escherichia coli Strains Isolated in Poland

2016 ◽  
Vol 65 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Aleksandra Januszkiewicz ◽  
Waldemar Rastawicki
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Virulence Gene ◽  
Virulence Determinants ◽  
E Coli ◽  
Heat Stable ◽  
Food Borne ◽  
Wide Range ◽  
Uremic Syndrome

Shiga toxin-producing Escherichia coli (STEC) strains also called verotoxin-producing E. coli (VTEC) represent one of the most important groups of food-borne pathogens that can cause several human diseases such as hemorrhagic colitis (HC) and hemolytic – uremic syndrome (HUS) worldwide. The ability of STEC strains to cause disease is associated with the presence of wide range of identified and putative virulence factors including those encoding Shiga toxin. In this study, we examined the distribution of various virulence determinants among STEC strains isolated in Poland from different sources. A total of 71 Shiga toxin-producing E. coli strains isolated from human, cattle and food over the years 1996 – 2010 were characterized by microarray and PCR detection of virulence genes. As stx1a subtype was present in all of the tested Shiga toxin 1 producing E. coli strains, a greater diversity of subtypes was found in the gene stx2, which occurred in five subtypes: stx2a, stx2b, stx2c, stx2d, stx2g. Among STEC O157 strains we observed conserved core set of 14 virulence factors, stable in bacteria genome at long intervals of time. There was one cattle STEC isolate which possessed verotoxin gene as well as sta1 gene encoded heat-stable enterotoxin STIa characteristic for enterotoxigenic E. coli. To the best of our knowledge, this is the first comprehensive analysis of virulence gene profiles identified in STEC strains isolated from human, cattle and food in Poland. The results obtained using microarrays technology confirmed high effectiveness of this method in determining STEC virulotypes which provides data suitable for molecular risk assessment of the potential virulence of this bacteria.

scholarly journals The prevalence and genomic context of Shiga toxin 2a genes in E. coli found in cattle

2020 ◽  
Author(s):  
Tomas Jinnerot ◽  
Angeles Tatiana Ponton Tomaselli ◽  
Gro S Johannessen ◽  
Robert Söderlund ◽  
Anne Margrete Urdahl ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Severe Disease ◽  
Amplicon Sequencing ◽  
Toxin Gene ◽  
Genomic Context ◽  
E Coli ◽  
Faecal Samples ◽  
Cattle Herds ◽  
Shiga Toxin Genes

AbstractShiga toxin-producing Escherichia coli (STEC) that cause severe disease predominantly carry the toxin gene variant stx2a. However, the role of Shiga toxin in the ruminant reservoirs of this zoonotic pathogen is poorly understood and strains that cause severe disease in humans (HUSEC) likely constitute a small and atypical subset of the overall STEC flora. The aim of this study was to investigate the presence of stx2a in samples from cattle and to isolate and characterize stx2a-positive E. coli. In nationwide surveys in Sweden and Norway samples were collected from individual cattle or from cattle herds, respectively. Samples were tested for Shiga toxin genes by real-time PCR and amplicon sequencing and stx2a-positive isolates were whole genome sequenced. Among faecal samples from Sweden, stx1 was detected in 37%, stx2 in 53% and stx2a in 5% and in skin samples in 64%, 79% and 2% respectively. In Norway, 79% of the herds were positive for stx1, 93% for stx2 and 17% for stx2a. Based on amplicon sequencing the most common stx2 types in samples from Swedish cattle were stx2a and stx2d. Multilocus sequence typing (MLST) of 39 stx2a-positive isolates collected from both countries revealed substantial diversity with 19 different sequence types. Only a few classical LEE-positive HUSEC were found among the stx2a-positive isolates, notably a single O121:H19 and an O26:H11. Known LEE-negative HUSEC lineages were also recovered including O113:H21 (ST-223), O130:H11 (ST-297), and O101:H33 (ST-330). We conclude that E. coli encoding stx2a in cattle are ranging from well-known HUSEC to unknown STEC variants. Comparison of isolates from human HUS cases to related STEC from the ruminant reservoirs can help identify combinations of virulence attributes necessary to cause HUS, as well as provide a better understanding of the routes of infection for rare and emerging pathogenic STEC.

scholarly journals Is Shiga Toxin-Producing Escherichia coli O45 No Longer a Food Safety Threat? The Danger is Still Out There

2020 ◽  
Vol 8 (5) ◽  
pp. 782 ◽  
Author(s):  
Yujie Zhang ◽  
Yen-Te Liao ◽  
Xiaohong Sun ◽  
Vivian C.H. Wu
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Evolutionary Relationship ◽  
Severe Illness ◽  
Next Generation Sequencing Technology ◽  
E Coli ◽  
Related Information ◽  
Foodborne Outbreaks ◽  
Enterocyte Effacement

Many Shiga toxin-producing Escherichia coli (STEC) strains, including the serogroups of O157 and most of the top six non-O157 serotypes, are frequently associated with foodborne outbreaks. Therefore, they have been extensively studied using next-generation sequencing technology. However, related information regarding STEC O45 strains is scarce. In this study, three environmental E. coli O45:H16 strains (RM11911, RM13745, and RM13752) and one clinical E. coli O45:H2 strain (SJ7) were sequenced and used to characterize virulence factors using two reference E. coli O45:H2 strains of clinical origin. Subsequently, whole-genome-based phylogenetic analysis was conducted for the six STEC O45 strains and nine other reference STEC genomes, in order to evaluate their evolutionary relationship. The results show that one locus of enterocyte effacement pathogenicity island was found in all three STEC O45:H2 strains, but not in the STEC O45:H16 strains. Additionally, E. coli O45:H2 strains were evolutionarily close to E. coli O103:H2 strains, sharing high homology in terms of virulence factors, such as Stx prophages, but were distinct from E. coli O45:H16 strains. The findings show that E. coli O45:H2 may be as virulent as E. coli O103:H2, which is frequently associated with severe illness and can provide genomic evidence to facilitate STEC surveillance.

scholarly journals Characterization of Shiga Toxin Gene (stx)-Positive and Intimin Gene (eae)-Positive Escherichia coli Isolates from Wastewater of Slaughterhouses in France

2006 ◽  
Vol 72 (5) ◽  
pp. 3245-3251 ◽  
Author(s):  
Estelle Loukiadis ◽  
Monique K�rour�dan ◽  
Lothar Beutin ◽  
Eric Oswald ◽  
Hubert Brug�re
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Wastewater Treatment Plants ◽  
Immunomagnetic Separation ◽  
Toxin Gene ◽  
E Coli ◽  
Treated Effluent ◽  
Colony Counting ◽  
Wastewater Samples

ABSTRACT Wastewater samples from 12 slaughterhouses located in different regions in France were tested for the presence of stx-positive and eae-positive Escherichia coli isolates, and characteristics of the isolates obtained were determined. A total of 224 wastewater samples were collected in wastewater treatment plants at different stages of wastewater processing. Altogether, 5,001 E. coli isolates were obtained by colony counting and screened for the presence of stx and eae genes by multiplex PCR. stx-positive and eae-positive E. coli isolates were detected in 25% of the samples collected; they were found in 13% and 3% of the samples obtained from treated effluent and sludge, respectively, suggesting that they could be spread into the environment. Screening of the samples collected by immunomagnetic separation allowed us to isolate 31 additional E. coli serogroup O157 isolates. Four of these isolates harbored stx and eae genes. All stx-positive and eae-positive E. coli isolates were analyzed for eae and stx genetic variants, as well as for additional virulence factors and serotypes. Our results suggest that the majority of the stx- and eae-positive E. coli isolates from wastewater have low virulence for humans. However, the diversity of the enterohemorrhagic E. coli-associated virulence factors in the strains indicates that the environment may play an important role in the emergence of new pathogenic enterohemorrhagic E. coli strains.

scholarly journals Enhanced expression of recombinant beta toxin of Clostridium perfringens type B using a commercially available Escherichia coli strain

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Fatemah Bakhshi ◽  
Reza Pilehchian Langroudi ◽  
Bahram Golestani Imani
Keyword(s):  
Escherichia Coli ◽  
Recombinant Protein ◽  
Clostridium Perfringens ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Toxin Gene ◽  
Type B ◽  
Iptg Induction ◽  
E Coli ◽  
Beta Toxin

Clostridium perfringens beta toxin is only produced by types B and C and plays an important role in many human and animal diseases, causing fatal conditions that originate in the intestines. We compared the expression of C. perfringens type B vaccine strain recombinant beta toxin gene in the Escherichia coli strains RosettaTM(DE3) and BL21(DE3). The beta toxin gene was extracted from pJETβ and ligated with pET22b(+). pET22β was transformed into E. coli strains BL21(DE3) and RosettaTM(DE3). Recombinant protein was expressed as a soluble protein after isopropyl β-D-1-thiogalactopyranoside (IPTG) induction in strain RosettaTM(DE3) but not in BL21(DE3). Expression was optimised by growing recombinant cells at 37 °C and at an induction of 0.5 mM, 1 mM, 1.5 mM IPTG. Expression was evaluated using sodium dodecyl sulfate Polyacrylamide gel electrophoresis (SDS-PAGE). The recombinant protein was purified via Ni-NTA and was analysed using western blot. We concluded that E. coli strain RosettaTM(DE3) can enhance the expression of C. perfringens recombinant beta toxin.Keywords: C. perfringens beta toxin (CPB); expression; RosettaTM; BL21

scholarly journals Prevalence of Hemolysin Genes and Comparison ofehxASubtype Patterns in Shiga Toxin-Producing Escherichia coli (STEC) and Non-STEC Strains from Clinical, Food, and Animal Sources

2013 ◽  
Vol 79 (20) ◽  
pp. 6301-6311 ◽  
Author(s):  
Sandra C. Lorenz ◽  
Insook Son ◽  
Anna Maounounen-Laasri ◽  
Andrew Lin ◽  
Markus Fischer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Shiga Toxin ◽  
Phenotypic Expression ◽  
Food Sources ◽  
Polymorphism Analysis ◽  
Subtype C ◽  
Content Type ◽  
E Coli ◽  
Subtype A

ABSTRACTShiga toxin-producingEscherichia coli(STEC) belonging to certain serogroups (e.g., O157 and O26) can cause serious conditions like hemolytic-uremic syndrome (HUS), but other strains might be equally pathogenic. While virulence factors, likestxandeae, have been well studied, little is known about the prevalence of theE. colihemolysin genes (hlyA,ehxA,e-hlyA, andsheA) in association with these factors. Hemolysins are potential virulence factors, andehxAandhlyAhave been associated with human illness, but the significance ofsheAis unknown. Hence, 435E. colistrains belonging to 62 different O serogroups were characterized to investigate gene presence and phenotypic expression of hemolysis. We further investigatedehxAsubtype patterns inE. coliisolates from clinical, animal, and food sources. WhilesheAandehxAwere widely distributed,e-hlyAandhlyAwere rarely found. Most strains (86.7%) were hemolytic, and significantly more hemolytic (95%) than nonhemolytic strains (49%) carriedstxand/oreae(P< 0.0001).ehxAsubtyping, as performed by using PCR in combination with restriction fragment length polymorphism analysis, resulted in six closely related subtypes (>94.2%), with subtypes A/D beingeae-negative STECs and subtypes B, C, E, and Feaepositive. Unexpectedly,ehxAsubtype patterns differed significantly between isolates collected from different sources (P< 0.0001), suggesting that simple linear models of exposure and transmission need modification; animal isolates carried mostly subtypes A/C (39.3%/42.9%), food isolates carried mainly subtype A (81.9%), and clinical isolates carried mainly subtype C (66.4%). Certain O serogroups correlated with particularehxAsubtypes: subtype A with O104, O113, and O8; B exclusively with O157; C with O26, O111, and O121.

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