<i>Escherichia coli</i>0157:H7 Strains That Express Shiga Toxin (Stx) 2 Alone Are More Neurotropic for Gnotobiotic Piglets Than Are Isotypes Producing Only Stx1 or Both Stx1 and Stx2

Donohue‐Rolfe, Arthur; Kondova, Ivanela; Oswald, Sibylle; Hutto, David; Tzipori, Saul

doi:10.1086/315421

Cited by 87 publications

(92 citation statements)

References 21 publications

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“…The low prevalence of stx 1 1 among E. coli O157:H7 isolates differs from the 47% prevalence of stx 1 1 isolates among non-O157 Shiga toxin-producing E. coli (STEC) recovered from beef carcass samples (3). It has been suggested that cells that carry stx 1 are less virulent than those that carry either stx 2 or both types of stx genes (6,9,10,22,30). The signi cantly higher prevalence of stx 2 1 and both stx 1 1 stx 2 1 genotypes among O157:H7 strains, compared with non-O157 STEC, suggests that a larger percentage of O157:H7 strains may be more highly virulent, which may, in turn, contribute to the higher proportion of O157:H7 strains associated with disease in the United States.…”

Section: Resultsmentioning

confidence: 99%

Characterization of O157:H7 and Other Escherichia coli Isolates Recovered from Cattle Hides, Feces, and Carcasses

Barkocy-Gallagher

Arthur

Rivera-Betancourt

et al. 2004

Journal of Food Protection

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In a previous study, the seasonal prevalence was reported for stx 1 Escherichia coli O157:H7 in feces and on hides and carcasses of cattle at processing. Overall, 1,697 O157:H7 isolates have now been characterized for the incidence of (i) eae O157 , hlyA, stx 1 , and stx 2 in the recovered isolates and (ii) presumptive rough and presumptive nonmotile isolates. Seven O157:H7 isolates (0.4%) lacked stx genes, although they carried eae and hlyA. All but one of the isolates carried both eae and hlyA. Approximately two-thirds of the isolates (64% when one isolate per sample was considered) carried both stx 1 and stx 2 . E. coli O157:H7 cells that harbored both stx 1 and stx 2 were more often recovered from hides in the fall (79% of the fall hide isolates) and winter (84% of the winter hide isolates) than in the spring (53%) and summer (59%). Isolates recovered from preevisceration carcasses showed a similar but not statistically signi cant trend. Twenty-three of the 25 O157:H7 isolates carrying stx 1 but not stx 2 were recovered during summer. Fifteen presumptive rough and 117 presumptive nonmotile stx 1 O157:H7 isolates were recovered. Ten (67%) of the presumptive rough isolates were recovered during summer. Ninety-ve of the presumptive nonmotile isolates (81%) were recovered during fall. Forty-eight percent of the false-positive isolates (175 of 363) tentatively identi ed as O157:H7 were O157 1 H7 2 and lacked eae O157 , hlyA, and stx. These data suggest that in beef processing samples (i) there are minor seasonal variations in the prevalence of stx genes among E. coli O157:H7 isolates, (ii) presumptive rough and presumptive nonmotile stx 1 O157:H7 isolates are present, (iii) E. coli O157:H7 isolates lacking stx genes may be rare, and (iv) O157 1 H7 2 isolates lacking stx genes can result in many false-positive results.Escherichia coli O157:H7 is an enteric pathogen that can cause diseases ranging from mild diarrhea to hemolytic uremic syndrome, kidney failure, and death (for reviews, see (17,21)). The Shiga toxins, Stx1 and Stx2, are considered to be the primary E. coli O157:H7 virulence factors, and the cells may harbor genes that express one or both of these toxins. However, the Shiga toxins alone may not be suf cient to cause disease. Additional known virulence factors include intimin and enterohemolysin, products of the eae and hlyA genes, respectively. Other virulence factors also may be involved.E. coli O157:H7 has been declared by the U.S. Food Safety and Inspection Service to be an adulterant in ground beef and nonintact beef products (2). Cattle are considered to be the primary reservoir of E. coli O157:H7 that is associated with human disease (8). Previously, we examined the seasonal prevalence of E. coli O157:H7 in feces and on hides and carcasses at beef processing plants (4). As with disease cases (8), the prevalence of E. coli O157:H7 was * Author for correspondence. ; E-mail: gallagher@email.marc.usda.gov. † Names are necessary to report factually on available data; however, the U.S. Departm...

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Section: Resultsmentioning

confidence: 99%

Characterization of O157:H7 and Other Escherichia coli Isolates Recovered from Cattle Hides, Feces, and Carcasses

Barkocy-Gallagher

Arthur

Rivera-Betancourt

et al. 2004

Journal of Food Protection

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“…In a study concerning Stx production as a single microbial factor, the most pathogenic strains for humans have been found to produce Stx2 only (9,34). The Stx2 toxin has been described as being 1,000 times more cytotoxic than Stx1 towards human renal microvascular endothelial cells, the putative target of Shiga toxins in the development of HUS (28).…”

Section: Discussionmentioning

confidence: 99%

Clinical Escherichia coli Strains Carrying stx Genes: stx Variants and stx -Positive Virulence Profiles

2002

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Altogether, 173 Shiga toxin-producing Escherichia coli (STEC) serotype O157 (n ‫؍‬ 111) and non-O157 (n ‫؍‬ 62) isolates from 170 subjects were screened by PCR-restriction fragment length polymorphism for eight different stx genes. The results were compiled according to serotypes, phage types of O157, production of Stx toxin and enterohemolysin, and the presence of eae. The stx genes occurred in 11 combinations; the most common were stx 2 with stx 2c (42%), stx 2 alone (21%), and stx 1 alone (16%). Of the O157 strains, 64% carried stx 2 with stx 2c versus 2% of the non-O157 strains (P < 0.001). In the non-O157 strains, the prevailing gene was stx 1 (99% versus 1% in O157 strains; P < 0.001). In addition, one strain (O Rough:H4:stx 2c ) which has not previously been described as associated with hemolytic-uremic syndrome (HUS) was found. Ten stx-positive virulence profiles were responsible for 71% of all STEC infections. Of these profiles, five accounted for 71% of the 21 strains isolated from 20 patients with HUS or thrombotic thrombocytopenic purpura (TTP). The strains having the virulence profile that caused mainly HUS or TTP or bloody diarrhea produced Stx with titers of >1:128 (90%) more commonly than did other strains (51%; P < 0.001). These strains were also more commonly enterohemolytic (98% versus 68% for other strains; P < 0.001) and possessed the eae gene (100%) more commonly than did other strains (74%; P < 0.001). A particular virulence profile, O157:H7:PT2:stx 2 :stx 2c :eae: Ehly, was significantly more frequently associated with HUS and bloody diarrhea than were other profiles (P ‫؍‬ 0.02) and also caused the deaths of two children. In this study, the risk factors for severe symptoms were an age of <5 years and infection by the strain of O157:H7:PT2 mentioned above.Shiga toxin-producing Escherichia coli (STEC) cells have emerged as new food-borne pathogens of clinical and public health concern (35). The most epidemic STEC serogroup has been O157, but about 200 other STEC serogroups have been identified (http://www.microbionet.com.au/frames/feature /vtec/brief01.html). Shiga toxins (Stx1 and/or Stx2) have a prominent role in the pathogenesis of STEC bacteria (15,20,26). The clinical picture of a STEC infection may vary from an asymptomatic state to bloody diarrhea and severe life-threatening complications such as hemolytic-uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP) (35). Children and elderly people have been more susceptible to STEC infections than healthy adults (32). It is estimated that the incidence of HUS varies from 2.0 to 3.0 cases per 100,000 children under 5 years of age (15) and from 0.9 to 1.2 cases per 100,000 in children under 18 years of age (5, 43).The pathogenesis of STEC infection in humans is not fully understood. It is considered to be multifactorial and dependent on several bacterial virulence factors such as enterohemolysin (Ehly) and the eae gene, in addition to host factors (6,35). A recent discovery of a quorum-sensing system, mediated by self-produced...

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“…Impact of Stx2 on regulation and expression of cytokine genes and cell adhesion molecules was greater than that of Stx1, delivering potential insights into the epidemiologically well-established fact that systemic complications are more often associated with infections caused by Stx2 producing EHEC strains than with Stx1 producers. 35 Furthermore, a number of transcription factors was regulated in HUVECs upon stimulation with Stxs. The transcription factors in most cases belonged to the TNF/stress-related signaling pathway (TRAF-1, TNF␣IP-2 and -3) and NFB (I␣, I⑀, NB2, FOS, JUNB, and RelB) pathway.…”

Section: Discussionmentioning

confidence: 99%

Molecular and functional analysis of Shiga toxin–induced response patterns in human vascular endothelial cells

Matussek

Lauber

Bergau

et al. 2003

Blood

100

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Enterohemorrhagic Escherichia coli (EHEC) is the major cause of hemolyticuremic syndrome (HUS) characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. EHEC produces one or more Shiga toxins (Stx1 and Stx2), and it was assumed that Stx's only relevant biologic activity was cell destruction through inhibition of protein synthesis. However, recent data indicate that in vivo the cytokine milieu may determine whether endothelial cells survive or undergo apoptosis/necrosis when exposed to Stxs. In this study, we analyzed the genome-wide expression patterns of human endothelial cells stimulated with subinhibitory concentrations of Stxs in order to characterize the genomic expression program involved in the vascular pathology of HUS. We found that Stxs elicited few, but reproducible, changes in gene expression. The majority of genes reported in this study encodes for chemokines and cytokines, which might contribute to the multifaceted inflammatory response of host endothelial cells observed in patients suffering from EHEC disease. In addition, our data provide for the first time molecular insights into the epidemiologically well-established higher pathogenicity of Stx2 over Stx1. (Blood. 2003;102: 1323-1332

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Escherichia coli0157:H7 Strains That Express Shiga Toxin (Stx) 2 Alone Are More Neurotropic for Gnotobiotic Piglets Than Are Isotypes Producing Only Stx1 or Both Stx1 and Stx2

Cited by 87 publications

References 21 publications

Characterization of O157:H7 and Other Escherichia coli Isolates Recovered from Cattle Hides, Feces, and Carcasses

Characterization of O157:H7 and Other Escherichia coli Isolates Recovered from Cattle Hides, Feces, and Carcasses

Clinical Escherichia coli Strains Carrying stx Genes: stx Variants and stx -Positive Virulence Profiles

Molecular and functional analysis of Shiga toxin–induced response patterns in human vascular endothelial cells

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