scholarly journals Lineage and Host Source Are Both Correlated with Levels of Shiga Toxin 2 Production by Escherichia coli O157:H7 Strains

2009 ◽  
Vol 76 (2) ◽  
pp. 474-482 ◽  
Author(s):  
Yongxiang Zhang ◽  
Chad Laing ◽  
Zhengzhong Zhang ◽  
Jennyka Hallewell ◽  
Chunping You ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Enzyme Linked Immunosorbent Assay ◽  
Escherichia Coli O157 ◽  
Rt Pcr ◽  
Genetic Lineages ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Flanking Region ◽  
Q Gene

ABSTRACT Escherichia coli O157:H7 strains fall into three major genetic lineages that differ in their distribution among humans and cattle. Several recent studies have reported differences in the expression of virulence factors between E. coli O157:H7 strains from these two host species. In this study, we wished to determine if important virulence-associated “mobile genetic elements” such as Shiga toxin 2 (Stx2)-encoding prophage are lineage restricted or are host source related and acquired independently of the pathogen genotype. DNA sequencing of the stx 2 flanking region from a lineage II (LII) strain, EC970520, revealed that the transcriptional activator gene Q in LI strain EDL933 (upstream of stx 2) is replaced by a pphA (serine/threonine phosphatase) homologue and an altered Q gene in this and all other LII strains tested. In addition, nearly all LI strains carried stx 2, whereas all LII strains carried variant stx 2c and 4 of 14 LI/II strains had copies of both stx 2 and variant stx 2c. Real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) demonstrated that LI and LI/II strains produce significantly more stx 2 mRNA and Stx2 than LII strains. However, among LI strains significantly more Stx2 is also produced by strains from humans than from cattle. Therefore, lineage-associated differences among E. coli O157:H7 strains such as prophage content, toxin type, and toxin expression may contribute to host isolation bias. However, the level of Stx2 production alone may also play an important role in the within-lineage association of E. coli O157:H7 strains with human clinical disease.

Seasonal Prevalence of Escherichia coli O157:H7 in Beef Cattle Feces†

2006 ◽  
Vol 69 (12) ◽  
pp. 3018-3020 ◽  
Author(s):  
M. J. ALAM ◽  
L. ZUREK
Keyword(s):  
Escherichia Coli ◽  
Beef Cattle ◽  
Shiga Toxin ◽  
Bacterial Colonization ◽  
Feedlot Cattle ◽  
Escherichia Coli O157 ◽  
Human Pathogen ◽  
E Coli ◽  
Cattle Feces ◽  
Shiga Toxin 2

Cattle are an asymptomatic reservoir of Escherichia coli O157:H7, but the bacterial colonization and shedding patterns are poorly understood. The prevalence and shedding of this human pathogen have been reported to be seasonal with rates typically increasing during warm months. The objectives of this study were (i) to assess the prevalence of E. coli O157:H7 in feces of feedlot cattle in Kansas during summer, fall, and winter months, and (ii) to characterize E. coli O157:H7 by screening for virulence factors. Of 891 fecal samples collected, 82 (9.2%) were positive for E. coli O157:H7. No significant differences in prevalence were detected among summer, fall, and winter months. The highest monthly prevalence (18.1%) was detected in February. All tested isolates were positive for stx2 (Shiga toxin 2) and eaeA (intimin) genes; 14 isolates (12.8%) also carried stx1. Our results indicate the prevalence of E. coli O157:H7 in beef cattle feces is not necessarily season dependent.

Comparison of Shiga-Like Toxin II Expression between Two Genetically Diverse Lineages of Escherichia coli O157:H7

2008 ◽  
Vol 71 (8) ◽  
pp. 1673-1678 ◽  
Author(s):  
SCOT E. DOWD ◽  
JASON B. WILLIAMS
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Enzyme Linked Immunosorbent Assay ◽  
Escherichia Coli O157 ◽  
Pathogenic Potential ◽  
Genomic Changes ◽  
E Coli ◽  
Gene Expression Analyses ◽  
Shiga Toxin 2 ◽  
The Difference

The existence of two separate lineages of Escherichia coli O157:H7 has previously been reported, and research indicates that one of these lineages (lineage I) might be more pathogenic toward human hosts. We postulated that the lineage more pathogenic expresses higher levels of Shiga toxin 2 (Stx2) than do the nonpathogenic lineage II. A comprehensive set of methodologies were used to investigate the difference in Stx2 protein and mRNA expression between the two lineages. An initial Stx2-specific enzyme-linked immunosorbent assay was conducted, and lineage I overall demonstrated significantly more toxin proteins expressed (P < 0.01). Gene expression analyses all showed significantly higher stx2 gene expression in lineage I (P = 0.02). PCR mapping revealed a possible explanation for decreased amounts of stx2 transcripts in the potentially nonpathogenic lineage II isolates, suggesting that genomic changes have modified the toxin-encoding region of the phage. This study provides additional data to support the existence of two diverse lineages of E. coli O157:H7, one of which may have lower pathogenic potential in relation to human hosts. The PCR described also provides a possible screening tool for E. coli O157 populations to differentiate these lineages. This study provides useful information on the ecology of E. coli O157, with broad implications within the clinical, scientific, and livestock industries.

scholarly journals Escherichia coli O157:H7 Strain Origin, Lineage, and Shiga Toxin 2 Expression Affect Colonization of Cattle

2009 ◽  
Vol 75 (15) ◽  
pp. 5074-5081 ◽  
Author(s):  
Ross M. S. Lowe ◽  
Danica Baines ◽  
L. Brent Selinger ◽  
James E. Thomas ◽  
Tim A. McAllister ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Escherichia Coli O157 ◽  
Human Origin ◽  
E Coli ◽  
Unknown Factor ◽  
Shiga Toxin 2 ◽  
The Impact ◽  
Dose Dependent

ABSTRACT Enterohemorrhagic Escherichia coli O157:H7 has evolved into an important human pathogen with cattle as the main reservoir. The recent discovery of E. coli O157:H7-induced pathologies in challenged cattle has suggested that previously discounted bacterial virulence factors may contribute to the colonization of cattle. The objective of the present study was to examine the impact of lineage type, cytotoxin activity, and cytotoxin expression on the amount of E. coli O157:H7 colonization of cattle tissue and cells in vitro. Using selected bovine- and human-origin strains, we determined that lineage type predicted the amount of E. coli O157:H7 strain colonization: lineage I > intermediate lineages > lineage II. All E. coli O157:H7 strain colonization was dose dependent, with threshold colonization at 103 to 105 CFU and maximum colonization at 107 CFU. We also determined that an as-yet-unknown factor of strain origin was the most dominant predictor of the amount of strain colonization in vitro. The amount of E. coli O157:H7 colonization was also influenced by strain cytotoxin activity and the inclusion of cytotoxins from lineage I or intermediate lineage strains increased colonization of a lineage II strain. There was a higher level of expression of the Shiga toxin 1 gene (stx 1) in human-origin strains than in bovine-origin strains. In addition, lineage I strains expressed higher levels of the Shiga toxin 2 gene (stx 2). The present study supports a role for strain origin, lineage type, cytotoxin activity, and stx 2 expression in modulating the amount of E. coli O157:H7 colonization of cattle.

Association of Prophage Antiterminator Q Alleles and Susceptibility to Food-Processing Treatments Applied to Escherichia coli O157 in Laboratory Media

2007 ◽  
Vol 70 (11) ◽  
pp. 2617-2619 ◽  
Author(s):  
AARON S. MALONE ◽  
AHMED E. YOUSEF ◽  
JEFFREY T. LEJEUNE
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Food Processing ◽  
High Pressure Processing ◽  
Toxin Gene ◽  
Escherichia Coli O157 ◽  
Surrogate Markers ◽  
Processing Efficiency ◽  
E Coli ◽  
Q Gene

Resistance of Escherichia coli O157 to inactivation by high-pressure processing, heat, and UV and gamma radiation was associated with the allele of the prophage-encoded antiterminator Q gene present upstream of the Shiga toxin gene stx2. Increased processing may be required to kill certain strains of E. coli O157, and the choice of strains used as surrogate markers for processing efficiency is critical.

scholarly journals Transduction of Enteric Escherichia coli Isolates with a Derivative of Shiga Toxin 2-Encoding Bacteriophage φ3538 Isolated from Escherichia coli O157:H7

1999 ◽  
Vol 65 (9) ◽  
pp. 3855-3861 ◽  
Author(s):  
Herbert Schmidt ◽  
Martina Bielaszewska ◽  
Helge Karch
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Laboratory Strain ◽  
Plaque Formation ◽  
Escherichia Coli O157 ◽  
Healthy Individuals ◽  
Wild Type ◽  
E Coli ◽  
Shiga Toxin 2 ◽  
Lysogenic Conversion

ABSTRACT We investigated the ability of a detoxified derivative of a Shiga toxin 2 (Stx2)-encoding bacteriophage to infect and lysogenize entericEscherichia coli strains and to develop infectious progeny from such lysogenized strains. The stx2 gene of the patient E. coli O157:H7 isolate 3538/95 was replaced by the chloramphenicol acetyltransferase (cat) gene from plasmid pACYC184. Phage φ3538(Δstx2 ::cat) was isolated after induction of E. coli O157:H7 strain 3538/95 with mitomycin. A variety of strains of enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), Stx-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), andE. coli from the physiological stool microflora were infected with φ3538(Δstx2 ::cat), and plaque formation and lysogenic conversion of wild-type E. coli strains were investigated. With the exception of one EIEC strain, none of the E. coli strains supported the formation of plaques when used as indicators for φ3538(Δstx2 ::cat). However, 2 of 11 EPEC, 11 of 25 STEC, 2 of 7 EAEC, 1 of 3 EIEC, and 1 of 6 E. coli isolates from the stool microflora of healthy individuals integrated the phage in their chromosomes and expressed resistance to chloramphenicol. Following induction with mitomycin, these lysogenic strains released infectious particles of φ3538(Δstx2 ::cat) that formed plaques on a lawn of E. coli laboratory strain C600. The results of our study demonstrate that φ3538(Δstx2 ::cat) was able to infect and lysogenize particular enteric strains of pathogenic and nonpathogenic E. coli and that the lysogens produced infectious phage progeny. Stx-encoding bacteriophages are able to spread stx genes among enteric E. coli strains.

Allelic types of long polar fimbriae in bovine and human Escherichia coli O157 strains

2012 ◽  
Vol 60 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Domonkos Sváb ◽  
István Tóth
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Phylogenetic Groups ◽  
Genetic Lineages ◽  
E Coli ◽  
Typing Scheme ◽  
Healthy Cattle ◽  
Reference Collection ◽  
Group D ◽  
Atypical Strains

Long polar fimbriae (Lpf) are recently discovered adhesins and increasingly important genetic markers of pathogenicEscherichia colistrains. The presence and genotype diversity of Lpf operons was screened in a collection of 97Escherichia coliO157 strains representing different pathotypes, isolated from healthy cattle (n = 43) and human patients (n = 54) in several countries. Individual structural genes of Lpf were scanned by PCR, and allelic variants were detected with a recently developed typing scheme. Ninety-five strains carried at least one whole Lpf operon (geneslpfABCDand/orlpfABCDE). The 64 enterohaemorrhagic (EHEC) and 24 enteropathogenic (EPEC) strains all carried two Lpf operons, allele 3 oflpfA1and allele 2 oflpfA2, a combination characteristic of the O157:H7/NM serotype. Out of the 9 bovine atypical (AT;stx-, eae-) strains, 7 carried one complete Lpf operon, allele 1 oflpfA2. The atypical strains belonged to main phylogenetic groups A and B1, while the EHEC and EPEC strains were from group D. Lpf variants carried by the 72 strains of theEscherichia coliReference Collection (ECOR) were determined with the same typing scheme. Alleles were detected in 25 strains, of which 6 were found negative for the respective Lpf operons in earlier studies. The marker value of the Lpf allelic combination for the O157:H7/NM serotype was confirmed, and further evidence was given for the presence of at least two different genetic lineages of atypical bovineE. coliO157 strains.

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.

Prevalence of shiga toxin-producing Escherichia coli O157, O26 and O111 in milk, meat and faeces of cattle, sheep and pigs slaughtered in Benin

2020 ◽  
Vol 152 ◽  
pp. 15667-15675
Author(s):  
Chakirath Folakè Arikè Salifou ◽  
Cyrille Boko ◽  
Isidore Houaga ◽  
Raoul Agossa ◽  
Isabelle Ogbankotan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Virulence Genes ◽  
Animal Origin ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Milk Samples ◽  
Food Of Animal Origin ◽  
Cattle Faeces ◽  
Risk Assessment And Management

Objectives: The study aimed to search for E. coli O157 and non-O157 in milk, meat and faeces of cattle, sheep and pigs slaughtered in Cotonou. Methodology and Results: One hundred and Seventy-Five (175) samples including 25 meat, 25 faeces per species and 25 milk from cattle were analysed for E. coli O157; O26 and O111 and the virulence genes were identified by PCR. The SAS software (1998) and the bilateral Z test were used to calculate and compare the identification frequencies. E. coli O157 was identified in 4% of cattle faeces, 4% of sheep faeces, and 20% of beef and, in 20% of milk samples. E. coli O26 was identified in 12% of cattle faeces and, in 8% of beef samples. E. coli O111 was identified at frequencies of 8%, and 12% in faeces of sheep and pigs, respectively. The eae gene was detected in 4% of beef, ovine meat, milk, pig faeces and in sheep faeces. stx1 was detected in 8% of milk, and in 4% of bovine and sheep faeces. The strains possessing the gene were all of E. coli O157 with the exception of one from pig faeces identified as O111. Conclusions and application of findings: The presence of these serogroups of E. coli with virulence genes poses a real food safety problem in Benin. This study findings must be taken into account for risk assessment and management related to the consumption of food of animal origin. Keywords: Benin, E. coli O157, O26, O111, faeces, meat, milk

Comparison of Rapid Enzyme-Linked Immunosorbent Assay and Immunomagnetic Separation Methods for Detection of Escherichia coli O157 in Fecal, Hide, Carcass, and Ground Beef Samples

2007 ◽  
Vol 70 (10) ◽  
pp. 2230-2234 ◽  
Author(s):  
T. W. THOMPSON ◽  
T. P. STEPHENS ◽  
G. H. LONERAGAN ◽  
M. F. MILLER ◽  
M. M. BRASHEARS
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Immunomagnetic Separation ◽  
Separation Method ◽  
Enzyme Linked Immunosorbent Assay ◽  
Escherichia Coli O157 ◽  
Perfect Agreement ◽  
Fecal Samples ◽  
E Coli ◽  
Beef Products

Rapid enzyme-linked immunosorbent assays (ELISAs) are approved for detection of Escherichia coli O157 in beef products. However, these kits have also been used in the industry to detect this pathogen on hides or in feces of cattle, although this use has not been validated. The objective of this study was to compare commercially available ELISAs (E. coli Now, Reveal, and VIP) with immunomagnetic separation along with selective media to detect E. coli O157 on hides, in feces, and in medium- and low-level-inoculated ground beef and carcasses (simulated by using briskets) samples. Naturally infected hide and fecal samples were subjected to both the immunomagnetic separation method and ELISAs for the detection of E. coli O157. Additionally, E. coli O157 inoculated and noninoculated ground beef and beef briskets were used to simulate meat and carcass samples. When comparing the detection results from the ELISAs (E. coli Now, Reveal, and VIP) to the immunomagnetic separation method, poor agreement was observed for fecal samples (kappa = 0.10, 0.02, and 0.03 for E. coli Now, Reveal, and VIP, respectively), and fair-to-moderate agreement was observed for hide samples (kappa = 0.30, 0.51, and 0.29 for E. coli Now, Reveal, and VIP, respectively). However, there was near-perfect agreement between the immunomagnetic separation method and ELISAs for ground beef (kappa = 1, 1, and 0.80 for E. coli Now, Reveal, and VIP, respectively) and brisket (kappa = 1, 1, and 1 for E. coli Now, Reveal, and VIP, respectively) samples. Assuming immunomagnetic separation is the best available method, these data suggest that the ELISAs are not useful in detecting E. coli O157 from hide or fecal samples. However, when ELISAs are used on ground beef and beef brisket samples they can be used with a high degree of confidence.

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