The Characterization of Shiga Toxin‐Non‐Producing <i>Escherichia coli</i> Serotype O157:H7 Isolated from Carcasses of Cattle at a Slaughter House

Itoh, Yoshihiro; Hayashi, Naoko; Katoh, Mikio; Yamamoto, Atsuko; Hayashi, Seizou; Maeda, Shigeki; Ezaki, Takayuki

doi:10.1111/j.1348-0421.1999.tb02458.x

Cited by 8 publications

(3 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although this strain did not contain either of the stx loci, the fact that it contained the eaeA locus is relevant, since this locus is linked to virulence in E. coli 0157 and non-0157 Shiga toxin-producing E. coli strains (23). The present results coincide with previous reports of absence of the stx virulence genes in E. coli 0157:H7 and E. coli 0157 strains from raw meat (5,8,20,21,38). This is the first report of isolation of a large number of .rtx-negative E. coli 0157 and E. coli 0157:H7 strains from ground beef in Mexico.…”

Section: Resultssupporting

confidence: 94%

Escherichia coli O157 in Ground Beef from Local Retail Markets in Pachuca, Mexico

Gómez‐Aldapa

Díz-Cruz

Cerna-Cortés³

et al. 2013

Journal of Food Protection

View full text Add to dashboard Cite

Escherichia coli O157 strains have been recognized as pathogenic bacteria, of which raw beef is a known vehicle. An evaluation was done of the presence of E. coli O157 in ground beef from local retail markets in Pachuca, Hidalgo State, Mexico. A total of 120 ground beef samples (500 g) were tested for E. coli O157 by simultaneous application of the U. S. Department of Agriculture, Food Safety and Inspection Service (FSIS)'s Microbiology Laboratory Guidebook culture procedure 5.05, and two commercial kits, Reveal for E. coli O157:H7 and Visual Immunoprecipitate Assay (VIP) Gold for enterohemorrhagic E. coli. Two incubation times (8 and 20 h) were used with the commercial kits. Presence of stx1, stx2, and eaeA loci was determined by multiplex PCR. Of 360 subsamples (120 per procedure), 12 samples were found to be E. coli O157 positive by the FSIS culture method. With VIP, 73 subsamples were presumptive positive after 8 h of enrichment, and 60 were presumptive positive after 20 h of enrichment. Of these, only 6 (8 h) and 8 (20 h) subsamples were confirmed true positives with the FSIS method. With Reveal, 60 subsamples were presumptive positive after 8 h of enrichment and 50 were presumptive positive after 20 h of enrichment. Of these, only 6 (8 h) and 8 (20 h) subsamples were confirmed as true positives with the FSIS method. A total of 57 E. coli O157:H7 and 21 E. coli O157 strains were isolated. None of the O157 or O157:H7 strains had stx1 or stx2 loci, and only one had the eaeA locus. To our knowledge, this is the first report of the presence of E. coli O157 in commercial ground beef from Mexico, and the first report of isolation of a large number of stx-negative E. coli O157 and E. coli O157:H7 strains in Mexico.

show abstract

Section: Resultssupporting

confidence: 94%

Escherichia coli O157 in Ground Beef from Local Retail Markets in Pachuca, Mexico

Gómez‐Aldapa

Díz-Cruz

Cerna-Cortés³

et al. 2013

Journal of Food Protection

View full text Add to dashboard Cite

show abstract

“…However, comparison of PFGE profiles showed distinct differences, as the non-Stxproducing O157:H7 strains clustered into a major clade, while TT12B clustered with the Stx-producing O157:H7 strains. Previously, Itoh et al (13) characterized four O157:H7 strains, isolated from cattle carcasses, that did not produce Stx but did carry other trait EHEC virulence factors. These strains were found to be closely related genotypically, and PFGE analysis of XbaI-digested DNA showed that they also shared similar profiles, hence suggesting that these non-Stx-producing O157:H7 strains had the same clonal descent (13).…”

Section: Discussionmentioning

confidence: 99%

“…Previously, Itoh et al (13) characterized four O157:H7 strains, isolated from cattle carcasses, that did not produce Stx but did carry other trait EHEC virulence factors. These strains were found to be closely related genotypically, and PFGE analysis of XbaI-digested DNA showed that they also shared similar profiles, hence suggesting that these non-Stx-producing O157:H7 strains had the same clonal descent (13). This is consistent with the results of our PFGE analysis, which showed similar clustering of non-Stx-producing O157:H7 strains.…”

Section: Discussionmentioning

confidence: 99%

Isogenic Strain of Escherichia coli O157:H7 That Has Lost both Shiga Toxin 1 and 2 Genes

Feng

Dey

Abe

et al. 2001

Clin Diagn Lab Immunol

View full text Add to dashboard Cite

An Escherichia coli O157:H7 strain isolated from a patient with hemorrhagic colitis was found to exhibit two slightly different colony morphology types on differential medium. Each morphological type, designated TT12A and TT12B, was isolated, and serological testing using various assays confirmed that both strains carried the O157 and the H7 antigens. Biochemical testing showed that the strains had identical profiles on AP120E analysis and, like typical O157:H7 strains, did not ferment sorbitol or exhibit ␤-glucuronidase activity. Analysis with a multiplex PCR assay showed that TT12B did not carry the gene for either Shiga toxin 1 (Stx1) or Stx2, whereas these genes were present in TT12A and the toxins were produced. Apart from that, both strains carried the ؉93 gusA mutation, the cluster I ehxA gene for enterohemolysin, and the eae gene for ␥-intimin, which are all characteristics of the O157:H7 serotype. Phenotypic assays confirmed that both strains exhibited enterohemolysin activity and the attachment and effacing lesion on HeLa cells. Multilocus enzyme electrophoresis analysis showed that the strains are closely related genetically and belong in the same clonal group. Pulsed-field gel electrophoresis (PFGE) typing of XbaI-digested genomic DNA revealed that the two strains differed by two bands but shared 90% similarity and clustered in the same clade. All other non-Stxproducing O157:H7 strains examined clustered in a major clade that was distinct from that of Stx-producing O157:H7 strains. The findings that TT12B was identical to TT12A, except for Stx production, and its PFGE profile is also more closely related to that of Stx-producing O157:H7 strains suggest that TT12B was derived from TT12A by the loss of both stx genes.Serotype O157:H7 is the prototypic enterohemorrhagic Escherichia coli (EHEC) strain and the predominant serotype implicated in food-borne infections worldwide. The EHEC group is characterized by its unique virulence factors. These include the eae gene, which encodes intimin, a protein essential for the cellular attachment and effacing (A/E) lesion, and a 60-mDa plasmid that carries the ehxA gene, which encodes enterohemolysin. However, the production of Shiga toxins (Stx), particularly Stx1 and Stx2, encoded by the phage-borne stx1 and stx2 genes, is probably the most defining trait of EHEC, as these two toxins are most often implicated in disease in humans.Isogenic, non-Stx-producing variants of EHEC provide useful controls in studying the role of Stx in pathogenesis in animal models. The production of Stx can be eliminated from strains by inducing the Stx-encoding phages with sublethal dosages of UV or antibiotics, although prophage release often results in cell lysis (16). Alternatively, Gunzer et al. (12) deleted the Stx2-encoding sequences from a wild-type O157:H7 strain with a suicide vector and thus constructed a toxin deletion isogen that did not produce Stx. In addition, Karch et al. (14) reported spontaneous loss of Stx production by EHEC strains other than O157:H7 during routi...

show abstract

Detection and frequency of VT1, VT2 and eaeA genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and abattoir environment in Istanbul

Yilmaz

Gün

Ugur

et al. 2006

International Journal of Food Microbiology

View full text Add to dashboard Cite

The Characterization of Shiga Toxin‐Non‐Producing Escherichia coli Serotype O157:H7 Isolated from Carcasses of Cattle at a Slaughter House

Cited by 8 publications

References 23 publications

Escherichia coli O157 in Ground Beef from Local Retail Markets in Pachuca, Mexico

Escherichia coli O157 in Ground Beef from Local Retail Markets in Pachuca, Mexico

Isogenic Strain of Escherichia coli O157:H7 That Has Lost both Shiga Toxin 1 and 2 Genes

Detection and frequency of VT1, VT2 and eaeA genes in Escherichia coli O157 and O157:H7 strains isolated from cattle, cattle carcasses and abattoir environment in Istanbul

Contact Info

Product

Resources

About