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Journal of Clinical Microbiology, March 1999, p. 497-503, Vol. 37, No. 3
Department of Population
Medicine1 and
Department of
Pathobiology,
Received 13 July 1998/Returned for modification 9 October
1998/Accepted 19 November 1998
Associations between known or putative virulence factors of Shiga
toxin-producing Escherichia coli and disease in humans were investigated. Univariate analysis and multivariate logistic regression analysis of a set of 237 isolates from 118 serotypes showed significant associations between the presence of genes for intimin
(eae) and Shiga toxin 2 (stx2) and
isolates from serotypes reported in humans. Similar associations were
found with isolates from serotypes reported in hemorrhagic colitis and
hemolytic-uremic syndrome. The enterohemorrhagic E. coli (EHEC) hemolysin gene was significantly associated with isolates from serotypes found in severe diseases in univariate analysis
but not in multivariate logistic regression models. A strong
association between the intimin and EHEC-hemolysin genes may explain
the lack of statistical significance of EHEC hemolysin in these
multivariate models, but a true lack of biological significance of the
hemolysin in humans or in disease cannot be excluded. This result
warrants further investigations of this topic. Multivariate analysis
revealed an interaction between the eae and
stx2 genes, thus supporting the hypothesis of
the synergism between the adhesin intimin and Shiga toxin 2. A strong
statistical association was observed between the
stx2 gene and severity of disease for a set of
112 human isolates from eight major serotypes. A comparison of 77 isolates of bovine origin and 91 human isolates belonging to six major
serotypes showed significant associations of the genes for Shiga toxin
1 and EspP protease with bovine isolates and an increased adherence on
HEp-2 cell cultures for human isolates, particularly from diarrheic
patients and healthy persons.
Shiga toxin-producing
Escherichia coli strains (STEC) were first implicated in
disease in the early 1980s by their association with hemolytic-uremic
syndrome (HUS) and hemorrhagic colitis (HC) (16, 27). STEC
have subsequently been associated with uncomplicated diarrhea
(23) and have been isolated from stools of healthy individuals. STEC are now considered a major cause of disease in
developed countries (10, 17). HC usually begins with
abdominal cramps and diarrhea, followed by bloody diarrhea. HUS
patients present with acute renal failure, thrombocytopenia, and
microangiopathic hemolytic anemia, often following a prodromal
diarrhea. HC and HUS are severe diseases which frequently require
hospitalization, and HUS may be fatal in up to 5% of cases. STEC
infections are mainly food borne, and bovine feces are the main source
of food contamination by this organism (10). A large variety
of STEC serotypes have been implicated in human disease, but some STEC serotypes found in cattle or in food have never or only very rarely been associated with severe human disease. These apparent differences in STEC serotype frequencies may, in part, be due to methodological issues, but differences in the ability of STEC strains to cause disease
are also likely contributors.
Based on in vitro and animal model studies, several virulence factors
have been described in STEC, the major one being Shiga toxins
(11). Two main categories of Shiga toxins have been
distinguished. E. coli Shiga toxin 1 (Stx1) is almost
identical to the Shiga toxin of Shigella dysenteriae in
amino acid sequence and cannot be distinguished from it serologically,
whereas Shiga toxin 2 (Stx2) is less related to the Shiga toxin of
Shigella and is not neutralized by antibodies to either Stx1
or Shiga toxin from S. dysenteriae (21, 35). As
is the case with enteropathogenic E. coli, some STEC strains
can tightly attach to epithelial cells of the intestine through an
adhesin called intimin. Such strains induce in the underlying cells
profound structural modifications called attaching and effacing
lesions. The genes related to these lesions, including the
eae (for E. coli attaching and effacing) gene,
which encodes intimin, are clustered in a pathogenicity island named
the locus for enterocyte effacement (LEE [19]). Recently, Schmidt and collaborators reported the genetic analysis of a
new plasmid-encoded hemolysin of STEC called enterohemorrhagic E. coli hemolysin (EHEC hemolysin; ehxA gene), which
seemed to be associated with severe clinical disease in humans
(31, 32). A protease (EspP), encoded by the same plasmid as
EHEC hemolysin, has also recently been described in some STEC serotypes
and has been suggested as an additional virulence factor of STEC
(5). There is actually no experimental proof for the role of
EHEC hemolysin and EspP in the virulence of STEC. They are therefore
only putative virulence factors, but for the sake of simplicity, they
will be included with the other virulence factors for the remainder of the discussion.
Previous studies have shown a large diversity in the distribution of
virulence factors among STEC strains (1, 3, 15, 41).
Associations have been suggested between the presence of some of these
factors in STEC and their virulence (24, 29, 30, 32).
However, these studies were often relatively small scale or examined
the distribution of each virulence factor separately, without
accounting for possible associations between virulence factors and
without considering the rest of the genome of the bacterial pathogen.
In the present study, the distribution of virulence factors in an
international collection of STEC isolates representing a broad spectrum
of serotypes from various sources was determined and analyzed by
methods which account for these possible influences. The first aim of
the study was to determine associations between virulence factors and
STEC disease in humans, based on classification of STEC isolates by
serotypes reported or not reported in the literature to have been
isolated from humans. Multivariate analysis was used to control for the
confounding effects of other virulence factors and of the genomic
background of the isolates by using serotype as a proxy. The second aim
was to examine the diversity of virulence factors in serotypes most frequently associated with disease and to detect associations between
any of these factors and the severity of disease in the actual patients
from whom the isolates were recovered. The last aim of this study was
to compare bovine and human STEC populations of the major serotypes
involved in human disease to test whether human STEC from these
serotypes that are most commonly isolated from patients with disease
form a different population than the bovine STEC population of the same serotypes.
STEC isolates.
Three different sets of STEC isolates were
used for the present study (Fig. 1). The
first set comprises 237 STEC isolates of 118 serotypes originating from
humans (n = 60), animals (n = 159), and
food (n = 18) that were selected from a larger
collection of STEC isolates deposited at the Health of Animals
Laboratory, Health Canada, Guelph, Ontario, Canada. Stratified random
sampling (strata are equivalent to serotypes) was used for the
selection in order to represent all the serotypes available in the
collection. The number of isolates per serotype was limited to a
maximum of three, and for those serotypes with less than three isolates
in the collection, all were used. The source collection is the fruit of
a long-term effort to collect representative STEC isolates from human
and nonhuman sources of diverse geographic origin. Based on an
extensive review of the literature, the isolates were classified into
four categories (Fig. 1). The first category within set 1 (listed
below) comprised 139 isolates belonging to 65 serotypes previously
reported in humans (O1:H20, O2:H5, O2:H6,
O2:H27, O2:H29, O5:H
0095-1137/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Associations between Virulence Factors of Shiga Toxin-Producing
Escherichia coli and Disease in Humans
ABSTRACT
Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
(nonmotile isolates)
O6:H, O7:H4, O8:H14, O15:H27, O15:H, O22:H8, O22:H16, O26:H11,
O26:H, O38:H21, O45:H2,
O48:H21, O55:H7, O55:H9, O75:H1,
O76:H19, O80:H, O82:H8, O84:H2, O89:H, O91:H10,
O91:H14, O91:H21, O91:H, O98:H, O103:H2, O111:H8, O111:H,
O112:H2, O113:H4, O113:H7, O113:H21, O114:H4, O115:H18, O117:H4,
O118:H12, O118:H16, O118:H30, O119:H6, O119:H, O121:H19, O126:H8, O126:H21, O128:H2,
O128:H, O132:H, O145:H,
O146:H8, O146:H21, O153:H25,
O157:H7, O157:H, O163:H19,
O163:H, O165:H25, O165:H, O171:H2, O172:H, and OX3:H21). The second category comprised 98 isolates of 53 serotypes not previously reported in humans (O2:H39, O2:H, O5:H11,
O6:H10, O6:H34, O8:H8, O8:H9, O8:H16, O8:H19, O8:H35, O15:H7, O22:H2,
O39:H49, O40:H8, O43:H2, O46:H38, O46:H, O49:H, O69:H11, O76:H25,
O77:H39, O84:H, O85:H, O88:H25, O91:H7, O98:H25, O110:H8, O111:H11,
O113:H, O115:H8, O116:H21, O118:H, O119:H5, O119:H25, O121:H7,
O126:H27, O128:H35, O130:H38, O132:H18, O136:H12, O136:H16, O136:H,
O139:H19, O142:H38, O145:H8, O153:H21, O153:H31, O156:H7, O156:H8,
O156:H25, O156:H, O163:H2, and O168:H8). The third category is a
subset of the first one and comprised 89 isolates belonging to 39 serotypes clearly identified in the literature as associated with HUS
and HC (underlined in the first list above). The fourth category of
isolates within set 1 corresponds to the remaining 148 isolates of 79 serotypes not previously reported in severe human disease. No
significant difference between categories in terms of mean number of
isolates per serotype was detected by a z test. The overall
mean number of isolates per serotype was 2.008. This supports our
attempt to control for serotype confounding in set 1 at the sampling
level.
View larger version (31K):
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FIG. 1.
Graphical representation of sampling strategy used to
obtain sets 1 to 3 of STEC isolates.
TABLE 1.
Numbers of STEC isolates of human and bovine origin in
strain sets 2 and 3 classified by serotype
Detection of stx1, stx2, eae, ehxA, and espP. All the isolates were examined for the presence of the stx1 and stx2 genes by PCR under the conditions described by Pollard and collaborators (25) except for three isolates for which the Cangene primers and conditions were used (26). The STEC strains EC910004 (serotype O46:H38; bovine origin) and 4304 (serotype O157:H7; human origin) served as positive controls, and the enteropathogenic E. coli strain 2348/69 served as a negative control for this test. The presence of eae was detected by PCR under the conditions described by Sandhu and coworkers (30) and was confirmed by dot blot hybridization when necessary. Strains 4304 and JM109 (43) served as positive and negative controls, respectively. For the dot blot hybridization, the probe consisted of the digoxigenin-labeled PCR product of strain 4304 produced with the DIG DNA labeling and detection kit (Boehringer, Mannheim, Germany). Cell lysates were obtained by resuspending the cells of a 500-µl overnight culture in Luria-Bertani broth in 100 µl of 0.4 M NaOH and heating it for 30 min at 80°C. One microliter of cell lysate was blotted on a Hybond membrane (Amersham Life Science, Little Chalfont, England) and bound by UV cross-linking. Hybridization was done following standard protocols (28) with stringent washing at 65°C in 0.2× SSC (20× SSC is 3 M NaCl plus 0.3 M sodium citrate, pH 7.0). Probe that remained bound to homologous sequences was detected with the DIG DNA labeling and detection kit following the supplier's instructions. The presence of ehxA was detected by PCR following the method of Sandhu and collaborators (29). Strains 4304 and 2348/69 served as positive and negative controls, respectively. Expression of the hemolytic phenotype was detected by incubating isolates overnight on washed sheep erythrocyte plates (2). When PCR and phenotype results were contradictory, dot blot hybridization of plasmid DNA was used to confirm the results with a digoxigenin-labeled probe made of the ehxA PCR product of strain 4304 as described by Boerlin and collaborators (4). Plasmid preparations were made by the alkaline lysis method (28) with one phenol-chloroform extraction, and 1 µl of each preparation was blotted onto Hybond membrane and bound by UV cross-linking. Hybridization and detection were done under the same conditions as for eae. For detection of espP, the same dot blot plasmid hybridization method was used as for ehxA. The digoxigenin-labeled probe consisted of a PCR product from strain 4304 covering the whole espP coding sequence. Strains 4304 and 2348/69 served as positive and negative controls, respectively. In case of questionable results, the detection was repeated by using Southern blotting (28) after running 15 µl of plasmid preparation in a 0.8% agarose gel. Hybridizations after Southern blotting were done as described above for dot blots. The presence of the genes was used as a proxy for the proteins they encode.
Adherence of STEC on HEp-2 cell cultures. HEp-2 cell adherence assays were performed according to standard protocols (7, 20). Briefly, 5 × 104 HEp-2 cells were incubated overnight in 400 µl of Eagle's minimum essential medium (EMEM) with antibiotic and 10% fetal calf serum (FCS) in each well of an eight-well permanox culture slide (Nalge Nunc International Naperville, Il.) at 37°C in a 5% CO2 atmosphere. The cells were washed three times with phosphate-buffered saline (PBS; pH 7.2) before use. The STEC strains to be tested were cultivated under aerobic conditions overnight at 37°C in Luria-Bertani broth and subcultured in EMEM with 10% FCS and 1 mM CaCl2 at 37°C overnight in a 5% CO2 atmosphere. Approximately 4 × 106 bacteria were inoculated in 300 µl of EMEM with 10% FCS and 1% D-mannose in each well of the culture slides and incubated for 3 h at 37°C in a 5% CO2 atmosphere. The wells were washed three times with PBS, and the cells were incubated for 3 more hours under the same conditions. The slides were then washed three times with PBS, and the cells were stained with the Diff-quick staining kit (Dade Diagnostics Inc. Aguada, Puerto Rico) following the instructions of the manufacturer. A total of 200 cells were examined under the microscope, and the cells with more than 10 adherent bacteria per cell were counted. Strain 6-264 (O157:H7) was used as a positive control for each batch of tests. To control for day-to-day variation, all the results were reported in proportion to the positive control. To control for within-day variations, all tests were done in duplicate, and the results are expressed as the average of the duplicates.
Statistical analysis. All analyses were performed with SAS for Windows version 6.12 (SAS Institute Inc., Cary, N.C.). For the analysis of associations between virulence factors and isolates of serotypes associated with humans or of serotypes known to be involved in severe disease (set 1), univariate analysis with chi-square tests (34) and multivariate analysis with logistic regression, including a backward-elimination procedure (threshold of 5% significance), were used (14). Associations between covariates were analyzed with McNemar's association tests (34). Reproducibility of the HEp-2 cell adherence assay was assessed by calculating an intracluster correlation coefficient (34) with a generalized linear model. To test for potential interactions between eae and the genes of the other factors in the logistic regression model, a manual forward procedure was used with a threshold of 5% significance (statistical interactions are present when two explanatory variables do not act independently on a response variable, thus suggesting the presence of synergism or antagonism at the biological level). The same procedures were used for the analysis of associations between virulence factors and severity of disease in isolates of human origin (set 2). However, for the latter analysis, the serotype variables were forced into the model, the level of adherence on HEp-2 was also included, and the eae variable was not used because all the isolates under study were positive for this characteristic. Finally, the same approach was used for the comparison of virulence factors and adherence level in STEC isolates of six major STEC serotypes of human origin versus those of bovine origin and of isolates from severe or less severe human disease versus those of bovine origin (set 3).
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RESULTS |
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Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
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Homogeneity of virulence factors within serotypes (set 1). All the isolates within a serotype were identical in terms of presence or absence of the eae gene for the 65 serotypes with more than one isolate in set 1. Within these 65 serotypes, the ehxA and espP genes were consistently present or absent in 54 and 52 serotypes, respectively. The variability in terms of Shiga toxin was slightly higher, with 43 and 41 serotypes with homogeneous patterns for stx1 and stx2, respectively. A strong association was present between eae and ehxA in the McNemar test (P < 0.0001; odds ratio [OR] = 9.3).
Associations between virulence factors and isolates of serotypes
reported in humans (set 1).
The distribution of the genes for the
virulence factors under study in the different categories of set 1 is
presented in Table 2. The results of the
chi-square tests for the comparison of isolates from serotypes found in
humans and those from serotypes not found in humans are reported in the
fourth column of Table 2. When modeling the associations among the five
virulence factors encoded by ehxA, espP,
eae, stx1, and
stx2 and presence in humans with a logistic
regression model, only eae and stx2
appeared as significant variables. This was the case in both a full
logistic model comprising all the virulence factors as independent
variables and in a reduced model resulting from the
backward-elimination procedure. The only significant interaction
between intimin and the other virulence factors of STEC at the 5%
level was between Eae and Stx2. The coefficients, corresponding ORs,
and P values for the two models with and without interaction
are reported in Table 3 and
4.
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Associations between virulence factors and isolates of serotypes reported in severe human disease (set 1). The procedures described above were also used to compare isolates from serotypes found in severe human disease with those from other serotypes. The results of the chi-square tests for this comparison are reported in the last column of Table 2. The logistic regression analysis of these data resulted in a model similar to the previous one, with only eae (coefficient = 1.67; P value = 0.0001; OR = 5.33) and stx2 (coefficient = 1.58; P value = 0.0001; OR = 4.86) significantly associated with isolates from serotypes found in severe disease. However, there was no evidence to suggest an interaction between intimin and the toxins.
Reproducibility of the HEp-2 cell adherence assay. Based on repeated trials of the HEp-2 cell adherence assays with a set of 15 isolates representing a broad range of adherence levels (0 to 1.4 in proportion to the positive control), an intracluster correlation coefficient of 0.89 was obtained. This result shows that 89% of the variability observed in the HEp-2 cell adherence assays is due to the strains and that only 11% of the variability is due to experimental error.
Associations between virulence factors of human STEC isolates from
eight major serotypes and disease severity (set 2).
The
distribution of the genes for the virulence factors under study in the
different categories of isolates from set 2 and the corresponding
P values for the chi-square tests are presented in Table
5. Among the variables tested (serotype,
ehxA, espP, stx1 and
stx2, and level of adherence on HEp-2 cell
cultures), stx1 was associated with
uncomplicated diarrhea and healthy individuals in the univariate
analysis (Table 5) and stx2 was significantly associated with severe disease in both the univariate analysis and the
multivariate logistic regression models (coefficient = 1.60;
P = 0.0038; OR = 4.95). There was no evidence
(P > 0.05) to suggest an interaction between the level
of adherence on cell cultures and the toxins.
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Comparison of distribution of virulence factors between isolates of
human and bovine origin among six common STEC serotypes (set 3).
The distribution of the genes for the virulence factors under study and
the level of adherence on HEp-2 cell cultures are presented in Table
6. Univariate analysis with chi-square
tests suggests a clear association between stx1
and bovine isolates compared to that with human isolates in general
(P value < 0.008). This crude analysis also suggests
the same association when comparing isolates of bovine origin with
those from humans with severe disease. In addition, STEC isolates from
patients with uncomplicated diarrhea and healthy individuals seem to
adhere significantly better to HEp-2 cells than do isolates from
cattle. Logistic regression confirms the association between
stx1 and bovine isolates, when compared to human
isolates in general, to isolates from patients with severe
STEC-associated disease, or to isolates from patients with
uncomplicated diarrhea and healthy individuals (Table
7). Logistic regression analysis shows
similar associations for espP and a significantly higher
level of adherence on HEp-2 cells for STEC from humans in general, and
particularly for STEC from patients with uncomplicated diarrhea and
healthy individuals when compared to bovine isolates (Table 7).
Finally, the logistic regression models also suggest a lower prevalence
of stx2 among isolates from patients with simple
diarrhea and healthy individuals than among those from cattle.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
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Among over 100 serotypes that have been recovered from
humans, serotypes O157:H7 and O157:H clearly represent the majority of isolates associated with disease. However, STEC organisms of many
other serotypes have been isolated from patients with HUS and HC with
variable frequencies. The differences in frequencies may be partially
related to reagent availability and methodological bias in the
detection of STEC (9). However, previous studies have also
shown a large spectrum of variability in virulence factor makeup in
STEC populations, and many researchers have attempted to correlate the
presence of specific recognized or putative virulence factors with
disease or severity of disease (10, 12, 17, 22, 24, 29, 30, 32,
33, 38, 39). The main conclusion of these previous investigations
has been that no single factor is responsible for the virulence of
STEC. In all these studies, the role of each factor has been analyzed
separately, without accounting for linkages between virulence factors.
This simple approach may bias estimates of the role of putative
virulence factors in disease pathogenesis by not correcting for the
confounding effect of other virulence factors and by neglecting joint
effects as observed in the case of synergistic mechanisms.
The eae gene and the entire LEE can be spread horizontally in STEC populations. However, this event seems to be rare, and the presence of the LEE is strongly associated with particular STEC lineages (4). The ehxA and the espP genes are carried on the same plasmid (5) and are therefore physically linked. Recent work in our laboratory suggests some associations between the LEE, the EHEC hemolysin plasmid, and the hemolysin itself (4). Previous studies have shown a certain degree of homogeneity for the presence of virulence factors within STEC serotypes (12, 29, 30), and the results of the present study confirm this observation. This is also true, although at a slightly lower level, for the phage-encoded (35) Shiga toxin genes. Analysis of E. coli populations by use of multilocus enzyme electrophoresis (6) has shown that serotype is a good marker for evolutionary lineages and is therefore also likely to be a good marker for the genetic background of STEC in terms of unknown virulence factors involved in the pathogenesis of STEC-associated diseases. Altogether, these data strongly support the approach taken in the present study, in which we tried to control for the confounding effects of the above-described genetic links among virulence factors and between virulence and serotype, an approach not used in previous works.
The first part of our study examined the association between the virulence factors of STEC and isolates from serotypes found in humans or in severe disease. Data on the exact origins of STEC isolates received in microbiological laboratories and reference collections are often very sparse, in particular with regard to clinical information. To overcome this limiting factor, we chose to use for the first part of the study a classification of isolates based on serotypes and their respective associations with humans as stated in the literature. Due to a lack of exhaustive descriptions and reporting in the literature, this approach may be subject to misclassification. It is expected that if this type of misclassification occurs, it will tend to decrease the significance of potential associations. Therefore, our approach may tend to ignore some weak but otherwise significant associations.
We observed no major difference in the frequency of ehxA and espP between isolates from serotypes found in humans and those not found in humans (Table 2). However, eae and stx2 were significantly more frequent in isolates from serotypes found in humans, and this association was even more significant when we compared isolates from serotypes clearly associated with severe disease to isolates from other serotypes. The reverse is true for stx1, which seems to be found more frequently among isolates from serotypes not found in humans than among those associated with humans. A significant difference in ehxA frequency was observed between isolates from serotypes specifically associated with severe disease and those that are not. This is not the case for espP. These crude data suggest an association of eae and stx2 with isolates of serotypes found in humans and possibly of eae, stx2, and ehxA with severity of disease (Table 2). Our results are in agreement with those of previous studies showing that ehxA (29, 32), eae (24), and stx2 (22, 33, 37) are found more frequently in STEC isolates from patients with severe disease than in other STEC populations and that stx1 may be associated with some STEC isolates of bovine origin (18, 40). However, in our multivariate analysis, only eae and stx2 were significantly associated with isolates from serotypes found in humans or with isolates from serotypes implicated in severe human disease. This suggests that most of the crude association of EHEC hemolysin with severe disease could be due to confounding effects of the major virulence factor intimin (Fig. 2A). Alternatively, collinearity between eae and ehxA in our model may obscure the true relationship between ehxA and human STEC isolates or disease (Fig. 2B). Thus, as has been shown by others (2, 29, 31, 32), our results confirm that EHEC hemolysin may represent an interesting virulence marker for STEC involved in severe human disease. However, our results also suggest that the role that EHEC hemolysin plays in the virulence of STEC may not be a major one, and therefore a reevaluation of its involvement in pathogenesis of severe disease due to STEC is warranted. Experimental work on animal and in vitro models is needed to clarify this point.
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Adherence of STEC on enterocytes may be a necessary step for persistent colonization of the human intestine and for an efficient local delivery of toxins, allowing a significant absorption of Shiga toxins in or through enterocytes and more severe effects on the organism than would have occurred without adherence. It is therefore not surprising that our analysis shows an association between eae and isolates from serotypes found in humans and, moreover, one of our logistic regression models also suggests a possible interaction between eae and stx2. It would be of interest, therefore, to confirm this finding on a larger collection of STEC with precisely defined origins.
The second part of our study concentrated on a few serotypes frequently associated with disease and evaluated the association of virulence factors within these serotypes with the severity of disease. Our results show a high prevalence of eae and ehxA in STEC isolates of these serotypes regardless of disease severity (Table 5). This confirms the observation made in the first part of the study suggesting an important role of intimin in strains from serotypes involved in disease and an association between the eae and ehxA genes in STEC populations. One observes a striking difference in prevalence of stx1 and stx2 between isolates from patients with severe disease and isolates from patients with simple diarrhea and healthy individuals. When we perform a logistic regression analysis (forcing the serotypes into the model), our results show a strong association between stx2 and severe disease: an stx2-positive isolate is approximately five times more likely to be associated with severe disease than an stx2-negative isolate of the same serotype. In view of the results of the first part of the study, this conclusion is not surprising, and it fits with suggestions made by others using animal models (8, 36, 39) or less extensive epidemiological studies based on serogroup O157 only (22, 33, 37). No other factor reaches a significant level of association with severe disease in the logistic regression analysis. Interestingly, our full logistic regression model suggests a positive but statistically nonsignificant association between EHEC hemolysin and severity of disease (data not shown). Due to the high prevalence of EHEC hemolysin and low diversity in the population, only the analysis of a much larger number of isolates would allow us to confirm this association and to obtain a valid estimate of its coefficient. However, the results of the first part of this study suggest that this coefficient would probably be relatively low. The observed level of STEC adherence on HEp-2 cell cultures did not show any significant association with severity of disease in the univariate or the multivariate logistic regression analysis for this part of the study.
The third part of our study used STEC isolates of six major serotypes frequently involved in disease to examine if STEC isolates of these serotypes isolated from humans may form a different population than those from the bovine STEC reservoir. Trends visible in the univariate analysis (Table 6) are confirmed by multivariate analysis (Table 7) and show a significant association of stx1 and espP with bovine STEC populations of these serotypes. They also show that human isolates of these eae-positive serotypes adhere more strongly on HEp-2 cell cultures than those from cattle. This fact is particularly marked in the case of isolates from patients with diarrhea or from healthy carriers and suggests that increased adherence on epithelial cells may play a role in the pathogenesis of STEC-associated diarrhea. Our results from cell cultures are in agreement with another report (38) suggesting that adherence may be a more important factor in STEC-associated diarrhea than Shiga toxins. However, our results should be confirmed with other cell lines more representative of polarized enterocytes (42) or in more complex systems, like the recently described adherence tests on organ cultures (13). These models may be more relevant for assessment of the adherence of STEC. They may better mimic the in vivo conditions encountered by STEC in the human bowel, thus allowing the bacteria to fully express characteristics only poorly expressed on HEp-2 cell cultures.
In conclusion, our results formally show that intimin and Stx2 are the virulence factors of STEC that are most strongly associated with disease in humans, and particularly with severe disease. These results suggest that STEC strains carrying the eae and stx2 genes should be the main targets of preventive and therapeutic measures. We could not detect any significant association of the newly described EspP protease with disease in humans. In contrast with previous studies using univariate analysis, the present work using multivariate analysis did not show any significant association between EHEC hemolysin and disease. This may be due either to a true lack of biological significance of EHEC hemolysin in the pathogenesis of STEC-associated diseases or to collinearity problems in multivariate modeling. The latter point clearly needs further clarification. Our results show that distribution of virulence factors and adherence levels differ between human and animal populations of the same serotypes. Thus, our results strongly suggest that STEC isolates from humans form a different population than those found in the bovine reservoir or that they are only a subpopulation of the latter.
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ACKNOWLEDGMENTS |
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We thank S. Aleksic, K. Bettelheim, A. Borczyk, A. Burnens, F. Ørskov, D. Piérard, and N. Strockbine for providing STEC strains of human origin for our collection. We are also indebted to K. Ziebell and S. Read for serotyping strains, to M. Shoukri for help in the statistical analysis of the data, and to J. Prescott for careful reviewing of the manuscript.
The research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. P.B. was the recipient of a grant from the Schweizerische Stiftung für Medizinische Biologische Stipendien during the present study.
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FOOTNOTES |
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* Corresponding author. Mailing address: Institut für Veterinär-Bakteriologie der Universität Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland. Phone: (41) 31-631 2368. Fax: (41) 31-631 2634. E-mail: patrick.boerlin{at}vbi.unibe.ch.
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REFERENCES |
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Top
Abstract
Introduction
Materials and methods
Results
Discussion
References
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| 1. |
Beutin, L.,
D. Geier,
H. Steinrück,
S. Zimmermann, and F. Scheutz.
1993.
Prevalence and some properties of verotoxin (Shiga-like toxin)-producing Escherichia coli in seven different species of healthy domestic animals.
J. Clin. Microbiol.
31:2483-2488 |
| 2. | Beutin, L., S. Zimmermann, and K. Gleier. 1996. Rapid detection and isolation of Shiga-like toxin (verocytotoxin-)-producing Escherichia coli by direct testing of individual enterohemorrhagic colonies from washed sheep blood agar plates in the VTEC-RPLA assay. J. Clin. Microbiol. 34:2812-2814[Abstract]. |
| 3. | Beutin, L., D. Geier, S. Zimmermann, and H. Karch. 1995. Virulence markers of Shiga-like toxin-producing Escherichia coli strains originating from healthy domestic animals of different species. J. Clin. Microbiol. 33:631-635[Abstract]. |
| 4. |
Boerlin, P.,
S. Chen,
J. K. Colbourne,
R. Johnson,
S. De Grandis, and C. Gyles.
1998.
Evolution of enterohemorrhagic Escherichia coli hemolysin plasmids and the locus for enterocyte effacement in Shiga toxin-producing E. coli.
Infect. Immun.
66:2553-2561 |
| 5. | Brunder, W., H. Schmidt, and H. Karch. 1997. EspP, a novel extracellular serine protease of enterohemorrhagic Escherichia coli O157:H7, cleaves human coagulation factor V. Mol. Microbiol. 24:767-778[Medline]. |
| 6. |
Caugant, D. A.,
B. R Levin,
I. Ørskov,
F. Ørskov,
C. Svanborg Eden, and R. K. Selander.
1985.
Genetic diversity in relation to serotype in Escherichia coli.
Infect. Immun.
49:407-413 |
| 7. | Cravioto, A., R. J. Gross, S. M. Scotland, and B. Rowe. 1979. An adhesive factor found in strains of Escherichia coli belonging to traditional infantile enteropathogenic serotypes. Curr. Microbiol. 3:95-99. |
| 8. |
Francis, D. H.,
R. A. Moxley, and C. Y. Andraos.
1989.
Edema disease-like brain lesions in gnotobiotic piglets infected with Escherichia coli serotype O157:H7.
Infect. Immun.
57:1339-1342 |
| 9. |
Goldwater, P. N., and K. A. Bettelheim.
1996.
An outbreak of hemolytic uremic syndrome due to Escherichia coli O157:H: or was it?
Emerg. Infect. Dis.
2:153-154[Medline]. (Letter.)
|
| 10. | Griffin, P. 1995. Escherichia coli O157:H7 and other enterohemorrhagic Escherichia coli, p. 739-761. In M. J. Blaser, P. D. Smith, J. I. Ravdin, H. B. Greenberg, and R. L. Guerrant (ed.), Infections of the gastrointestinal tract. Raven Press, New York, N.Y. |
| 11. | Gyles, C. L. 1992. Escherichia coli cytotoxins and enterotoxins. Can. J. Microbiol. 38:734-746[Medline]. |
| 12. |
Gyles, C.,
R. Johnson,
A. Gao,
K. Ziebell,
D. Piérard,
S. Aleksic, and P. Boerlin.
1998.
Association of enterohemorrhagic Escherichia coli hemolysin with serotypes of Shiga-like toxin-producing Escherichia coli of human and bovine origins.
Appl. Environ. Microbiol.
64:4134-4141 |
| 13. |
Hicks, S.,
G. Frankel,
J. B. Kaper,
G. Dougan, and A. D. Phillips.
1998.
Role of intimin and bundle-forming pili in enteropathogenic Escherichia coli adhesion to pediatric intestinal tissue in vitro.
Infect. Immun.
66:1570-1578 |
| 14. | Hosmer, D. W., and S. Lemeshow. 1989. Applied logistic regression. John Wiley & Sons, Inc., New York, N.Y. |
| 15. | Johnson, R. P., R. C. Clarke, J. B. Wilson, S. C. Read, K. Rahn, S. A. Renwick, K. A. Sandhu, D. Alves, M. A. Karmali, H. Lior, S. McEwen, J. S. Spika, and C. L. Gyles. 1996. Growing concerns and recent outbreaks involving non-O157:H7 serotypes of verocytotoxigenic Escherichia coli. J. Food Protect. 59:1112-1122. |
| 16. | Karmali, M. A., B. T. Steele, M. Petric, and C. Lim. 1983. Sporadic cases of hemolytic uremic syndrome associated with fecal cytotoxin and cytotoxin-producing Escherichia coli. Lancet i:619-620. |
| 17. |
Karmali, M. A.
1989.
Infections by verocytotoxin-producing Escherichia coli.
Clin. Microbiol. Rev.
2:15-38 |
| 18. | Mainil, J. G., E. R. Jacquemin, A. E. Kaeckenbeeck, and P. H. Pohl. 1993. Association between the effacing (eae) gene and the Shiga-like toxin-encoding genes in Escherichia coli isolates from cattle. Am. J. Vet. Res. 54:1064-1068[Medline]. |
| 19. |
McDaniel, T. K.,
K. G. Jarvis,
M. S. Donnenberg, and J. B. Kaper.
1995.
A genetic locus for enterocyte effacement conserved among diverse enterobacterial pathogens.
Proc. Natl. Acad. Sci. USA
92:1664-1668 |
| 20. | Nataro, J. P., J. B. Kaper, R. Robins Browne, V. Prado, P. Vial, and M. M. Levine. 1987. Patterns of adherence of diarrheagenic Escherichia coli to HEp-2 cells. Pediatr. Infect. Dis. J. 6:829-831[Medline]. |
| 21. |
O'Brien, A. D., and R. K. Holmes.
1987.
Shiga and Shiga-like toxins.
Microbiol. Rev.
51:206-220 |
| 22. | Ostroff, S. M., M. A. Neil, J. A. Lewis, N. Hargrett-Bean, and J. M. Kobayashi. 1989. Toxin genotypes and plasmid profiles as determinants of systemic sequelae in Escherichia coli O157:H7 infections. J. Infect. Dis. 160:994-998[Medline]. |
| 23. | Pai, C. H., N. Ahmed, H. Lior, W. M. Johnson, H. V. Sims, and D. E. Woods. 1988. Epidemiology of sporadic diarrhea due to verocytotoxin-producing Escherichia coli: a two years prospective study. J. Infect. Dis. 157:1054-1057[Medline]. |
| 24. | Piérard, D., D. Stevens, L. Moriau, H. Lior, and S. Lauwers. 1997. Isolation and virulence factors of verocytotoxin-producing Escherichia coli in human stool samples. Clin. Microbiol. Infect. 3:531-540. [Medline] |
| 25. |
Pollard, D. R.,
W. M. Johnson,
H. Lior,
S. D. Tyler, and K. R. Rozee.
1990.
Rapid and specific detection of verotoxin genes in Escherichia coli by polymerase chain reaction.
J. Clin. Microbiol.
28:540-545 |
| 26. | Read, S., and K. Ziebell. Unpublished data. |
| 27. | Riley, L. W., R. S. Remis, S. D. Helgerson, H. B. McGee, J. G. Wells, B. R. Davis, R. J. Hebert, E. S. Olcott, L. M. Johnson, N. T. Hargrett, P. A. Blake, and M. L. Cohen. 1983. Hemorrhagic colitis associated with a rare Escherichia coli serotype. N. Engl. J. Med. 308:681-685[Abstract]. |
| 28. | Sambrook, J., E. F. Fritsch, and T. Maniatis. 1989. Molecular cloning: a laboratory manual, 2nd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. |
| 29. | Sandhu, K. S., R. C. Clarke, and C. L. Gyles. 1997. Hemolysin phenotypes and genotypes of eaeA-positive and eaeA-negative bovine verotoxigenic Escherichia coli. Adv. Exp. Med. Biol. 412:295-302[Medline]. |
| 30. | Sandhu, K. S., R. C. Clarke, K. McFadden, A. Brouwer, M. Louie, J. Wilson, H. Lior, and C. L. Gyles. 1996. Prevalence of the eaeA gene in verotoxigenic Escherichia coli strains from dairy cattle in Southwestern Ontario. Epidemiol. Infect. 116:1-7[Medline]. |
| 31. | Schmidt, H., L. Beutin, and H. Karch. 1995. Molecular analysis of the plasmid-encoded hemolysin of Escherichia coli O157:H7 strain EDL 933. Infect. Immun. 63:1055-1061[Abstract]. |
| 32. | Schmidt, H., and H. Karch. 1996. Enterohemolytic phenotypes and genotypes of Shiga-toxin-producing Escherichia coli O111 strains from patients with diarrhea and hemolytic-uremic syndrome. J. Clin. Microbiol. 34:2364-2367[Abstract]. |
| 33. | Scotland, S. M., G. A. Willshaw, H. R. Smith, and B. Rowe. 1987. Properties of strains of Escherichia coli belonging to serogroup O157 with special reference to production of vero cytotoxins VT1 and VT2. Epidemiol. Infect. 99:613-624[Medline]. |
| 34. | Snedecor, G. W., and W. G. Cochran. 1989. Statistical methods. Iowa State University Press, Ames. |
| 35. |
Strockbine, N. A.,
R. M. Marques,
J. W. Newland,
H. W. Smith,
R. K. Holmes, and A. D. O'Brien.
1986.
Two toxin-converting phages from Escherichia coli O157:H7 strain 933 encode antigenetically distinct toxins with similar biologic activities.
Infect. Immun.
53:135-140 |
| 36. |
Tesh, V. L.,
J. A. Burris,
J. W. Owens,
V. M. Gordon,
E. A. Wadolkowski,
A. D. O'Brien, and J. E. Samuel.
1993.
Comparison of the relative toxicities of Shiga-like toxins type I and type II for mice.
Infect. Immun.
61:3392-3402 |
| 37. | Thomas, A., H. Chart, T. Cheasty, H. R. Smith, J. A. Frost, and B. Rowe. 1993. Vero cytotoxin-producing Escherichia coli, particularly serogroup O157, associated with human infections in the United Kingdom: 1989-91. Epidemiol. Infect. 110:591-600[Medline]. |
| 38. |
Tzipori, S.,
R. Gibson, and J. Montanaro.
1989.
Nature and distribution of mucosal lesions associated with enteropathogenic and enterohemorrhagic Escherichia coli in piglets and the role of plasmid-mediated factors.
Infect. Immun.
57:1142-1150 |
| 39. |
Wadolkowski, E. A.,
L. M. Sung,
J. A. Burris,
J. E. Samuel, and A. D. O'Brien.
1990.
Acute renal tubular necrosis and death of mice orally infected with Escherichia coli strains that produce Shiga-like toxin type II.
Infect. Immun.
58:3959-3965 |
| 40. | Wieler, L. H., R. Bauerfeind, and G. Baljer. 1992. Characterization of Shiga-like toxin producing Escherichia coli (SLTEC) isolated from calves with and without diarrhoea. Int. J. Med. Microbiol. Virol. Parasitol. Infect. Dis. 276:243-253. |
| 41. | Willshaw, G. A., S. M. Scotland, H. R. Smith, and B. Rowe. 1992. Properties of vero cytotoxin-producing Escherichia coli of human origin of O serogroups other than O157. J. Infect. Dis. 166:797-802[Medline]. |
| 42. |
Winsor, D. K.,
S. Ashkenazi,
R. Chiovetti, and T. G. Cleary.
1992.
Adherence of enterohemorrhagic Escherichia coli strains to a human colonic epithelial cell line (T84).
Infect. Immun.
60:1613-1617 |
| 43. | Yanisch-Perron, C., J. Vieira, and J. Messing. 1985. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene 33:103-119[Medline]. |
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72: 7030-7039
[Abstract] [Full Text] -
Gamage, S. D., Patton, A. K., Hanson, J. F., Weiss, A. A.
(2004). Diversity and Host Range of Shiga Toxin-Encoding Phage. Infect. Immun.
72: 7131-7139
[Abstract] [Full Text] -
Winter, K. R. K., Stoffregen, W. C., Dean-Nystrom, E. A.
(2004). Shiga Toxin Binding to Isolated Porcine Tissues and Peripheral Blood Leukocytes. Infect. Immun.
72: 6680-6684
[Abstract] [Full Text] -
De Baets, L., Van der Taelen, I., De Filette, M., Pierard, D., Allison, L., De Greve, H., Hernalsteens, J.-P., Imberechts, H.
(2004). Genetic Typing of Shiga Toxin 2 Variants of Escherichia coli by PCR-Restriction Fragment Length Polymorphism Analysis. Appl. Environ. Microbiol.
70: 6309-6314
[Abstract] [Full Text] -
Gamage, S. D., McGannon, C. M., Weiss, A. A.
(2004). Escherichia coli Serogroup O107/O117 Lipopolysaccharide Binds and Neutralizes Shiga Toxin 2. J. Bacteriol.
186: 5506-5512
[Abstract] [Full Text] -
Djordjevic, S. P., Ramachandran, V., Bettelheim, K. A., Vanselow, B. A., Holst, P., Bailey, G., Hornitzky, M. A.
(2004). Serotypes and Virulence Gene Profiles of Shiga Toxin-Producing Escherichia coli Strains Isolated from Feces of Pasture-Fed and Lot-Fed Sheep. Appl. Environ. Microbiol.
70: 3910-3917
[Abstract] [Full Text] -
Cobbold, R. N., Rice, D. H., Szymanski, M., Call, D. R., Hancock, D. D.
(2004). Comparison of Shiga-Toxigenic Escherichia coli Prevalences among Dairy, Feedlot, and Cow-Calf Herds in Washington State. Appl. Environ. Microbiol.
70: 4375-4378
[Abstract] [Full Text] -
Vernozy-Rozand, C., Montet, M. P., Bertin, Y., Trably, F., Girardeau, J. P., Martin, C., Livrelli, V., Beutin, L.
(2004). Serotyping, stx2 Subtyping, and Characterization of the Locus of Enterocyte Effacement Island of Shiga Toxin-Producing Escherichia coli and E. coli O157:H7 Strains Isolated from the Environment in France. Appl. Environ. Microbiol.
70: 2556-2559
[Abstract] [Full Text] -
Bielaszewska, M., Fell, M., Greune, L., Prager, R., Fruth, A., Tschape, H., Schmidt, M. A., Karch, H.
(2004). Characterization of Cytolethal Distending Toxin Genes and Expression in Shiga Toxin-Producing Escherichia coli Strains of Non-O157 Serogroups. Infect. Immun.
72: 1812-1816
[Abstract] [Full Text] -
Beutin, L., Krause, G., Zimmermann, S., Kaulfuss, S., Gleier, K.
(2004). Characterization of Shiga Toxin-Producing Escherichia coli Strains Isolated from Human Patients in Germany over a 3-Year Period. J. Clin. Microbiol.
42: 1099-1108
[Abstract] [Full Text] -
Blanco, M., Blanco, J. E., Mora, A., Dahbi, G., Alonso, M. P., Gonzalez, E. A., Bernardez, M. I., Blanco, J.
(2004). Serotypes, Virulence Genes, and Intimin Types of Shiga Toxin (Verotoxin)-Producing Escherichia coli Isolates from Cattle in Spain and Identification of a New Intimin Variant Gene (eae-{xi}). J. Clin. Microbiol.
42: 645-651
[Abstract] [Full Text] -
Vaz, T. M. I., Irino, K., Kato, M. A. M. F., Dias, A. M. G., Gomes, T. A. T., Medeiros, M. I. C., Rocha, M. M. M., Guth, B. E. C.
(2004). Virulence Properties and Characteristics of Shiga Toxin-Producing Escherichia coli in Sao Paulo, Brazil, from 1976 through 1999. J. Clin. Microbiol.
42: 903-905
[Abstract] [Full Text] -
Ritchie, J. M., Thorpe, C. M., Rogers, A. B., Waldor, M. K.
(2003). Critical Roles for stx2, eae, and tir in Enterohemorrhagic Escherichia coli-Induced Diarrhea and Intestinal Inflammation in Infant Rabbits. Infect. Immun.
71: 7129-7139
[Abstract] [Full Text] -
Muehlherr, J. E., Zweifel, C., Corti, S., Blanco, J. E., Stephan, R.
(2003). Microbiological Quality of Raw Goat's and Ewe's Bulk-Tank Milk in Switzerland. J DAIRY SCI
86: 3849-3856
[Abstract] [Full Text] -
Karmali, M. A., Mascarenhas, M., Shen, S., Ziebell, K., Johnson, S., Reid-Smith, R., Isaac-Renton, J., Clark, C., Rahn, K., Kaper, J. B.
(2003). Association of Genomic O Island 122 of Escherichia coli EDL 933 with Verocytotoxin-Producing Escherichia coli Seropathotypes That Are Linked to Epidemic and/or Serious Disease. J. Clin. Microbiol.
41: 4930-4940
[Abstract] [Full Text] -
Jenkins, C., Willshaw, G. A., Evans, J., Cheasty, T., Chart, H., Shaw, D. J., Dougan, G., Frankel, G., Smith, H. R.
(2003). Subtyping of virulence genes in verocytotoxin-producing Escherichia coli (VTEC) other than serogroup O157 associated with disease in the United Kingdom. J Med Microbiol
52: 941-947
[Abstract] [Full Text] -
Matussek, A., Lauber, J., Bergau, A., Hansen, W., Rohde, M., Dittmar, K. E. J., Gunzer, M., Mengel, M., Gatzlaff, P., Hartmann, M., Buer, J., Gunzer, F.
(2003). Molecular and functional analysis of Shiga toxin-induced response patterns in human vascular endothelial cells. Blood
102: 1323-1332
[Abstract] [Full Text] -
Shaikh, N., Tarr, P. I.
(2003). Escherichia coli O157:H7 Shiga Toxin-Encoding Bacteriophages: Integrations, Excisions, Truncations, and Evolutionary Implications. J. Bacteriol.
185: 3596-3605
[Abstract] [Full Text] -
Sheoran, A. S., Chapman, S., Singh, P., Donohue-Rolfe, A., Tzipori, S.
(2003). Stx2-Specific Human Monoclonal Antibodies Protect Mice against Lethal Infection with Escherichia coli Expressing Stx2 Variants. Infect. Immun.
71: 3125-3130
[Abstract] [Full Text] -
Friedrich, A. W., Borell, J., Bielaszewska, M., Fruth, A., Tschape, H., Karch, H.
(2003). Shiga Toxin 1c-Producing Escherichia coli Strains: Phenotypic and Genetic Characterization and Association with Human Disease. J. Clin. Microbiol.
41: 2448-2453
[Abstract] [Full Text] -
Brett, K. N., Hornitzky, M. A., Bettelheim, K. A., Walker, M. J., Djordjevic, S. P.
(2003). Bovine Non-O157 Shiga Toxin 2-Containing Escherichia coli Isolates Commonly Possess stx2-EDL933 and/or stx2vhb Subtypes. J. Clin. Microbiol.
41: 2716-2722
[Abstract] [Full Text] -
Burk, C., Dietrich, R., Acar, G., Moravek, M., Bulte, M., Martlbauer, E.
(2003). Identification and Characterization of a New Variant of Shiga Toxin 1 in Escherichia coli ONT:H19 of Bovine Origin. J. Clin. Microbiol.
41: 2106-2112
[Abstract] [Full Text] -
Blanco, M., Blanco, J. E., Mora, A., Rey, J., Alonso, J. M., Hermoso, M., Hermoso, J., Alonso, M. P., Dahbi, G., Gonzalez, E. A., Bernardez, M. I., Blanco, J.
(2003). Serotypes, Virulence Genes, and Intimin Types of Shiga Toxin (Verotoxin)-Producing Escherichia coli Isolates from Healthy Sheep in Spain. J. Clin. Microbiol.
41: 1351-1356
[Abstract] [Full Text] -
Jenkins, C., Perry, N. T., Cheasty, T., Shaw, D. J., Frankel, G., Dougan, G., Gunn, G. J., Smith, H. R., Paton, A. W., Paton, J. C.
(2003). Distribution of the saa Gene in Strains of Shiga Toxin-Producing Escherichia coli of Human and Bovine Origins. J. Clin. Microbiol.
41: 1775-1778
[Abstract] [Full Text] -
Blanco, J., Blanco, M., Blanco, J. E., Mora, A., Gonzalez, E. A., Bernardez, M. I., Alonso, M. P., Coira, A., Rodriguez, A., Rey, J., Alonso, J. M., Usera, M. A.
(2003). Verotoxin-Producing Escherichia coli in Spain: Prevalence, Serotypes, and Virulence Genes of O157:H7 and Non-O157 VTEC in Ruminants, Raw Beef Products, and Humans. Exp. Biol. Med.
228: 345-351
[Abstract] [Full Text] -
Brett, K. N., Ramachandran, V., Hornitzky, M. A., Bettelheim, K. A., Walker, M. J., Djordjevic, S. P.
(2003). stx1c Is the Most Common Shiga Toxin 1 Subtype among Shiga Toxin-Producing Escherichia coli Isolates from Sheep but Not among Isolates from Cattle. J. Clin. Microbiol.
41: 926-936
[Abstract] [Full Text] -
Ritchie, J. M., Wagner, P. L., Acheson, D. W. K., Waldor, M. K.
(2003). Comparison of Shiga Toxin Production by Hemolytic-Uremic Syndrome-Associated and Bovine-Associated Shiga Toxin-Producing Escherichia coli Isolates. Appl. Environ. Microbiol.
69: 1059-1066
[Abstract] [Full Text] -
Eklund, M., Leino, K., Siitonen, A.
(2002). Clinical Escherichia coli Strains Carrying stx Genes: stx Variants and stx-Positive Virulence Profiles. J. Clin. Microbiol.
40: 4585-4593
[Abstract] [Full Text] -
Arthur, T. M., Barkocy-Gallagher, G. A., Rivera-Betancourt, M., Koohmaraie, M.
(2002). Prevalence and Characterization of Non-O157 Shiga Toxin-Producing Escherichia coli on Carcasses in Commercial Beef Cattle Processing Plants. Appl. Environ. Microbiol.
68: 4847-4852
[Abstract] [Full Text] -
Wang, G., Clark, C. G., Rodgers, F. G.
(2002). Detection in Escherichia coli of the Genes Encoding the Major Virulence Factors, the Genes Defining the O157:H7 Serotype, and Components of the Type 2 Shiga Toxin Family by Multiplex PCR. J. Clin. Microbiol.
40: 3613-3619
[Abstract] [Full Text] -
Chiyoda, S., Takeda, T., Aoki, Y.
(2002). Shiga Toxin 2 Induces Macrophage-Granulocyte Colonies from Human Bone Marrow and Cord Blood Stem Cells. Infect. Immun.
70: 5316-5318
[Abstract] [Full Text] -
Wagner, P. L., Waldor, M. K.
(2002). Bacteriophage Control of Bacterial Virulence. Infect. Immun.
70: 3985-3993
[Full Text] -
Reischl, U., Youssef, M. T., Kilwinski, J., Lehn, N., Zhang, W. L., Karch, H., Strockbine, N. A.
(2002). Real-Time Fluorescence PCR Assays for Detection and Characterization of Shiga Toxin, Intimin, and Enterohemolysin Genes from Shiga Toxin-Producing Escherichia coli. J. Clin. Microbiol.
40: 2555-2565
[Abstract] [Full Text] -
Khan, A., Das, S. C., Ramamurthy, T., Sikdar, A., Khanam, J., Yamasaki, S., Takeda, Y., Nair, G. B.
(2002). Antibiotic Resistance, Virulence Gene, and Molecular Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Diverse Sources in Calcutta, India. J. Clin. Microbiol.
40: 2009-2015
[Abstract] [Full Text] -
Fasano, A
(2002). Toxins and the gut: role in human disease. Gut
50: iii9-14
[Abstract] [Full Text] -
Zhang, W., Bielaszewska, M., Kuczius, T., Karch, H.
(2002). Identification, Characterization, and Distribution of a Shiga Toxin 1 Gene Variant (stx1c) in Escherichia coli Strains Isolated from Humans. J. Clin. Microbiol.
40: 1441-1446
[Abstract] [Full Text] -
ADWAN, K., ABU-HASAN, N., ESSAWI, T., BDIR, M.
(2002). Isolation and characterisation of Shiga toxigenic Escherichia coli strains from northern Palestine. J Med Microbiol
51: 332-335
[Abstract] [Full Text] -
Welinder-Olsson, C., Badenfors, M., Cheasty, T., Kjellin, E., Kaijser, B.
(2002). Genetic Profiling of Enterohemorrhagic Escherichia coli Strains in Relation to Clonality and Clinical Signs of Infection. J. Clin. Microbiol.
40: 959-964
[Abstract] [Full Text] -
Mukherjee, J., Chios, K., Fishwild, D., Hudson, D., O'Donnell, S., Rich, S. M., Donohue-Rolfe, A., Tzipori, S.
(2002). Human Stx2-Specific Monoclonal Antibodies Prevent Systemic Complications of Escherichia coli O157:H7 Infection. Infect. Immun.
70: 612-619
[Abstract] [Full Text] -
HOEY, D.E. E., CURRIE, C., ELSE, R. W., NUTIKKA, A., LINGWOOD, C. A., GALLY, D. L., SMITH, D. G. E.
(2002). Expression of receptors for verotoxin 1 from Escherichia coli O157 on bovine intestinal epithelium. J Med Microbiol
51: 143-149
[Abstract] [Full Text] -
Paton, A. W., Paton, J. C.
(2002). Direct Detection and Characterization of Shiga Toxigenic Escherichia coli by Multiplex PCR for stx1, stx2, eae, ehxA, and saa. J. Clin. Microbiol.
40: 271-274
[Abstract] [Full Text] -
Nakajima, H., Kiyokawa, N., Katagiri, Y. U., Taguchi, T., Suzuki, T., Sekino, T., Mimori, K., Ebata, T., Saito, M., Nakao, H., Takeda, T., Fujimoto, J.
(2001). Kinetic Analysis of Binding between Shiga Toxin and Receptor Glycolipid Gb3Cer by Surface Plasmon Resonance. J. Biol. Chem.
276: 42915-42922
[Abstract] [Full Text] -
Kimura, T., Tani, S., Matsumoto, Y.-i., Takeda, T.
(2001). Serum Amyloid P Component Is the Shiga Toxin 2-neutralizing Factor in Human Blood. J. Biol. Chem.
276: 41576-41579
[Abstract] [Full Text] -
McNally, A., Roe, A. J., Simpson, S., Thomson-Carter, F. M., Hoey, D. E. E., Currie, C., Chakraborty, T., Smith, D. G. E., Gally, D. L.
(2001). Differences in Levels of Secreted Locus of Enterocyte Effacement Proteins between Human Disease-Associated and Bovine Escherichia coli O157. Infect. Immun.
69: 5107-5114
[Abstract] [Full Text] -
Ramachandran, V., Hornitzky, M. A., Bettelheim, K. A., Walker, M. J., Djordjevic, S. P.
(2001). The Common Ovine Shiga Toxin 2-Containing Escherichia coli Serotypes and Human Isolates of the Same Serotypes Possess a Stx2d Toxin Type. J. Clin. Microbiol.
39: 1932-1937
[Abstract] [Full Text] -
Djordjevic, S. P., Hornitzky, M. A., Bailey, G., Gill, P., Vanselow, B., Walker, K., Bettelheim, K. A.
(2001). Virulence Properties and Serotypes of Shiga Toxin-Producing Escherichia coli from Healthy Australian Slaughter-Age Sheep. J. Clin. Microbiol.
39: 2017-2021
[Abstract] [Full Text] -
Wagner, P. L., Neely, M. N., Zhang, X., Acheson, D. W. K., Waldor, M. K., Friedman, D. I.
(2001). Role for a Phage Promoter in Shiga Toxin 2 Expression from a Pathogenic Escherichia coli Strain. J. Bacteriol.
183: 2081-2085
[Abstract] [Full Text] -
Feng, P., Weagant, S. D., Monday, S. R.
(2001). Genetic Analysis for Virulence Factors in Escherichia coli O104:H21 That Was Implicated in an Outbreak of Hemorrhagic Colitis. J. Clin. Microbiol.
39: 24-28
[Abstract] [Full Text] -
Kobayashi, H., Shimada, J., Nakazawa, M., Morozumi, T., Pohjanvirta, T., Pelkonen, S., Yamamoto, K.
(2001). Prevalence and Characteristics of Shiga Toxin-Producing Escherichia coli from Healthy Cattle in Japan. Appl. Environ. Microbiol.
67: 484-489
[Abstract] [Full Text] -
Wieler, L. H., Busse, B., Steinrück, H., Beutin, L., Weber, A., Karch, H., Baljer, G.
(2000). Enterohemorrhagic Escherichia coli (EHEC) Strains of Serogroup O118 Display Three Distinctive Clonal Groups of EHEC Pathogens. J. Clin. Microbiol.
38: 2162-2169
[Abstract] [Full Text] -
Fukushima, H., Hoshina, K., Gomyoda, M.
(2000). Selective Isolation of eae-Positive Strains of Shiga Toxin-Producing Escherichia coli. J. Clin. Microbiol.
38: 1684-1687
[Abstract] [Full Text] -
Pradel, N., Livrelli, V., De Champs, C., Palcoux, J.-B., Reynaud, A., Scheutz, F., Sirot, J., Joly, B., Forestier, C.
(2000). Prevalence and Characterization of Shiga Toxin-Producing Escherichia coli Isolated from Cattle, Food, and Children during a One-Year Prospective Study in France. J. Clin. Microbiol.
38: 1023-1031
[Abstract] [Full Text] -
Hurley, B. P., Jacewicz, M., Thorpe, C. M., Lincicome, L. L., King, A. J., Keusch, G. T., Acheson, D. W. K.
(1999). Shiga Toxins 1 and 2 Translocate Differently across Polarized Intestinal Epithelial Cells. Infect. Immun.
67: 6670-6677
[Abstract] [Full Text] -
Wagner, P. L., Acheson, D. W. K., Waldor, M. K.
(1999). Isogenic Lysogens of Diverse Shiga Toxin 2-Encoding Bacteriophages Produce Markedly Different Amounts of Shiga Toxin. Infect. Immun.
67: 6710-6714
[Abstract] [Full Text] -
Nakao, H., Kiyokawa, N., Fujimoto, J., Yamasaki, S., Takeda, T.
(1999). Monoclonal Antibody to Shiga Toxin 2 Which Blocks Receptor Binding and Neutralizes Cytotoxicity. Infect. Immun.
67: 5717-5722
[Abstract] [Full Text]
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