Previous Article | Next Article 
Infection and Immunity, March 2004, p. 1812-1816, Vol. 72, No. 3
0019-9567/04/$08.00+0 DOI: 10.1128/IAI.72.3.1812-1816.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Characterization of Cytolethal Distending Toxin Genes and Expression in Shiga Toxin-Producing Escherichia coli Strains of Non-O157 Serogroups
Martina Bielaszewska,1* Marina Fell,1 Lilo Greune,2 Rita Prager,3 Angelika Fruth,3 Helmut Tschäpe,3 M. Alexander Schmidt,2 and Helge Karch1
Institut für Hygiene, Universitätsklinikum Münster,1
Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung (ZMBE), Universität Münster, 48149 Münster,2
Robert-Koch Institut, Bereich Wernigerode, 38855 Wernigerode, Germany3
Received 29 August 2003/
Returned for modification 7 November 2003/
Accepted 11 December 2003

ABSTRACT
We identified cytolethal distending toxin and its gene (
cdt)
in 17 of 340 non-O157 Shiga toxin-producing
Escherichia coli (STEC) strains (serotypes O73:H18, O91:H21, O113:H21, and O153:H18),
all of which were
eae negative.
cdt is either chromosomal and
homologous to
cdt-V (serotypes O73:H18, O91:H21, and O113:H21)
or plasmidborne and identical to
cdt-III (serotype O153:H18).
Among
eae-negative STEC,
cdt was associated with disease (
P = 0.003).

INTRODUCTION
Cytolethal distending toxins (CDTs) are tripartite toxins encoded
by three adjacent or slightly overlapping genes (
cdtA,
cdtB,
and
cdtC) (
15,
19,
20,
22) and found in multiple pathogens (
5).
All
cdt genes are required for arrest of the eukaryotic cell
cycle in the G
1 or G
2 phase (
5,
15,
19,
20), which characteristically
distends cell morphology and eventually causes cell death (
5,
14,
15,
19). Recent studies suggest that within the CDT holotoxin,
CdtB is the enzymatically active subunit (
14,
15), which damages
(through DNase I-like activity) (
6,
14) host cell DNA (
14),
thereby triggering the DNA damage checkpoint response (
5) that
arrests the cell cycle (
5,
6,
14,
15). The CdtA and CdtC polypeptides
constitute the heterodimeric subunit (
15,
16) that is required
for CDT binding to target cells (
16) and for intracellular delivery
of CdtB (
15). Five different
Escherichia coli cdt sequences
have been reported. Four of the sequences encode CDT-I (
22),
CDT-II (
20), CDT-III (
19), and CDT-IV (
24) in enteropathogenic
E. coli (EPEC),
E. coli causing extraintestinal infections,
and animal pathogenic
E. coli. We recently described the fifth
cdt allelic cluster in sorbitol-fermenting (SF) Shiga toxin
(Stx)-producing
E. coli (STEC) O157:H
- strain 493/89 (
11); we
have designated the fifth sequence (following nomenclature recommendations)
(
5)
cdt-V. CDT-V is produced by most (87%) SF STEC O157:H
- isolates
and a subset (6%) of STEC O157:H7 isolates (
11).
In this study we used PCR to detect all presently known E. coli cdt alleles to determine the frequency and distribution of cdt among non-O157 STEC human isolates. We sequenced cdt genes from STEC isolates of different serotypes, determined their genomic locations, and investigated their expression characteristics through the use of a cell culture assay. The cell culture assay was also applied (in parallel with PCR analyses) to identify potential producers of CDT encoded by an allele or alleles undetectable by the PCR strategies employed.

The frequency and distribution of cdt among non-O157 STEC isolates.
A total of 340 non-O157 STEC (130
eae-positive and 210
eae-negative)
isolates belonging to 100 different serotypes (Table
1) and
isolated from patients with hemolytic-uremic syndrome (HUS)
(
n = 66) or uncomplicated diarrhea (
n = 206) and from asymptomatic
carriers (
n = 68) (
7,
8) were subjected to PCRs with primers
targeting
cdt-I,
cdt-II,
cdt-III,
cdt-IV, and
cdt-V (Table
2).
cdt-I,
cdt-II, and
cdt-IV were identified in none of these strains
(Table
1). A total of 3 and 14 strains tested positive for
cdt-III and
cdt-V, respectively (Table
1); all others tested negative.
The
cdt-positive STEC isolates belonged to serotype O153:H18
(
cdt-III+ strains) and to serotypes O73:H18, O91:H21, and O113:H21
(
cdt-V+ strains) (Table
1). Within these serotypes, all or most
isolates possessed
cdt (Table
1). Each of the 17
cdt-positive
STEC isolates was
eae negative (Table
1) and originated from
patients (3 of the patients had HUS and 14 had uncomplicated
diarrhea) (Table
3). Among the 210
eae-negative STEC isolates
investigated,
cdt was significantly more frequent in those from
patients with HUS (3 of 7) and in those from patients with diarrhea
(14 of 138) than in those from asymptomatic carriers (0 of 65)
(
P = 0.0018 and
P = 0.0057, respectively; Fisher's exact test).
The difference in the level of association of
cdt with HUS versus
that with diarrhea was not significant (
P = 0.073).

cdt sequencing.
cdt gene clusters were amplified with primer pair c338f and
c2767r or primer pair cdtIII-f and cdtIII-r (Table
2) and sequenced
using an automated ABI Prism 3100 Avant Genetic Analyzer and
an ABI Prism BigDye Terminator Ready Reaction cycle sequencing
kit (Perkin-Elmer Applied Biosystems, Weiterstadt, Germany).
Sequences were analyzed with DNASIS software (Hitachi Software).
Homology searches were performed using the EMBL-GenBank database.
cdt clusters from STEC isolates of serotypes O73:H18 (strain
2996/96), O91:H21 (strain 9282/01), O113:H21 (strain 5249/01),
and O153:H18 (strain 9063/02) consisted of three open reading
frames (ORFs) of 777, 810, and 546 bp each, which encode CdtA,
CdtB, and CdtC, respectively. The
cdt sequences from STEC O91:H21
strain 9282/01 (GenBank accession number
AY365042) and STEC
O113:H21 strain 5249/01 (GenBank accession number
AY365043)
were 100% identical and differed by 1, 2, and 2 nucleotides
in their
cdtA,
cdtB, and
cdtC genes, respectively, from the
corresponding genes of STEC O73:H18 strain 2996/96 (GenBank
accession number
AY365045). The sequences of
cdtA,
cdtB, and
cdtC and the deduced amino acid sequences of the corresponding
proteins from these three strains were identical or closely
related (

98.8% homology) to those published for
cdt-V and CDT-V, respectively, from SF STEC O157:H
- strain 493/89
(GenBank accession number
AJ508930) (
11). In contrast, the sequences
of each of the three
cdt genes and of the corresponding proteins
from STEC O153:H18 strain 9063/02 (GenBank accession number
AY365044) were 100% identical to those published for
cdt-III and CDT-III, respectively, from necrotoxigenic
E. coli (NTEC)
O15:H21 strain S5 (GenBank accession number
U89305) (
19). CDT-III
from the STEC O153:H18 isolate differed from CDT-V from STEC
O91:H21, O113:H21, and O73:H18 isolates by 15, 15, and 16 amino
acid residues, respectively (Fig.
1). With a single exception,
the amino acid differences were confined to CdtA and CdtC whereas
CdtB proteins were conserved (Fig.
1).

Genomic location of cdt.
To determine the
cdt location in non-O157 STEC isolates,
EcoRV-digested
genomic DNA and isolated plasmids (
23) were electrophoretically
separated (Fig.
2A, Fig.
3A) and hybridized with digoxigenin-labeled
cdtB probe derived from strain 493/89 by PCR with primers c1309f
and c2166r (Table
2). The probe was detected using a DIG luminescent
detection kit (Roche Molecular Biochemicals, Mannheim, Germany).
SF STEC O157:H
- strain 493/89 (which contains
cdt-V on the chromosome)
(
11) and NTEC O78:H? strain 1404 (which harbors
cdt-III on a
large Vir plasmid) (
19) were used as controls. A single fragment
of genomic DNA between 5.5 and 18 kb in size hybridized with
the
cdtB probe in each of five representative STEC isolates
harboring
cdt-V (Fig.
2B, lanes 1 to 5), in each of the three
STEC isolates harboring
cdt-III (Fig.
2B, lanes 6 to 8), and
in both control strains (Fig.
2B, lanes 9 and 10). In contrast,
only large (140- or 175-kb) plasmids of the three
cdt-III-positive
STEC O153:H18 isolates (Fig.
3B, lanes 6 to 8) and the large
plasmid of strain 1404 (Fig.
3B, lane 10) hybridized with the
cdtB probe. No signals were elicited from large plasmids of
any of the five STEC isolates harboring
cdt-V (Fig.
3B, lanes
1 to 5) or of strain 493/89 (Fig.
3B, lane 9). Taken together,
these data demonstrate that
cdt-V in STEC isolates O73:H18,
O91:H21, and O113:H21 is chromosomal whereas
cdt-III in STEC
O153:H18 is on a large plasmid.

CDT expression.
Using a Chinese hamster ovary (CHO) cell assay (
11), each of
the 17
cdt-harboring STEC isolates produced CDT, as evidenced
by a progressive distension of the cells for up to 5 days after
their exposure to culture filtrates of these strains (data not
shown). CDT titers ranged from 1:2 to 1:64 (Table
3). No CDT
activity was detected by the CHO assay in any of the remaining
323 STEC isolates that were PCR negative for
cdt-I,
cdt-II,
cdt-III,
cdt-IV, and
cdt-V, suggesting that no additional
cdt allele undetectable by the PCR approaches used occurred among
the STEC strains investigated. In accordance with a previous
report that CHO cells are resistant to Stx (
13), none of the
340 STEC isolates caused an Stx-like cytotoxic effect on these
cells.
Our data demonstrate that two different cdt alleles with different genomic locations and specific serotype associations encode active CDT in non-O157 STEC strains. The finding that the location of each of the two cdt alleles is restricted to a limited spectrum of serotypes raises questions about the acquisition of these genes. In SF STEC O157:H- strain 493/89, cdt-V is located within the late gene region of bacteriophage P2 (11), suggesting that it might have been acquired by transduction (11). Currently, we seek to determine whether cdt-V in non-O157 STEC strains is also located within a phage genome, to characterize such a phage, and to find out whether the association of cdt-V with several particular STEC serotypes reflects a specific ability of such strains to be infected with a cdt-encoding phage. In addition, the finding of cdt-III on large plasmids of STEC O153:H18 strains is intriguing and prompts efforts to determine whether these plasmids are conjugative plasmids similar to the cdt-III-harboring Vir plasmid of NTEC strains (19) and whether a horizontal transfer through such plasmids contributes to the spread of cdt-III among STEC strains. The association of CDT with particular non-O157 STEC serotypes parallels the situation reported for EPEC (1, 2, 9) and extraintestinal pathogenic E. coli (12) and suggests that (as proposed for the latter two E. coli groups) (2, 9, 12) the particular serotypes might denote specific STEC clones that frequently harbor cdt and produce CDT. Until now, no association of CDT with diarrhea was found in epidemiological studies investigating EPEC (1, 2). Also, the absence of CDT from all eae-positive STEC isolates investigated in this study, including those belonging to the major non-O157 serogroups (serogroups O26, O103, O111, and O145) (Table 1) that frequently cause HUS (7), demonstrates that CDT is not essential for the pathogenicity of eae-positive STEC. However, our finding of a significant association between CDT production by eae-negative STEC isolates and clinical symptoms in patients infected with such strains suggests that CDT might contribute to the pathogenicity of these organisms. In particular, the finding of CDT in STEC strains of serotypes O91:H21 and O113:H21 that can cause serious human diseases including HUS (this study and references 10, 13 and 18) despite their lacking eae (18), an STEC factor associated with virulence and with HUS (3), warrants further investigation of a potential role of CDT in the pathogenesis of diseases caused by these strains. Our data thus add to a growing literature profiling the loci (beyond those of genes encoding Stx or intimin) potentially needed for STEC to cause disease.

Nucleotide accession sequence numbers.
The nucleotide sequences of
cdt genes from STEC strains 9282/01
(O91:H21), 5249/01 (O113:H21), 9063/02 (O153:H18), and 2996/96
(O73:H18) have been entered into the GenBank database (accession
numbers
AY365042 to
AY365045, respectively).

ACKNOWLEDGMENTS
This study was supported by a grant from the Deutsche Forschungsgemeinschaft
(DFG), no. KA 717/4-1, by a grant from the Bundesministerium
für Bildung und Forschung (BMBF) Project Network of Competence
Pathogenomics Alliance "Functional Genomic research on enterohaemorrhagic,
enteropathogenic and enteroaggregative
Escherichia coli", Project
Group "Schmidt/Karch, Universitätsklinikum Münster"
(BD numbers 119523 and 207800), and by a grant from Fonds der
Chemischen Industrie.
We thank P. I. Tarr (Washington University School of Medicine, St. Louis, Mo.) for critical reading of the manuscript and stimulating discussions, colleagues who provided us with CDT control strains, and M. Hüllsman (Münster) and B. Knüppel (Wernigerode) for skillful technical assistance.

FOOTNOTES
* Corresponding author. Mailing address: Institut für Hygiene, Universitätsklinikum Münster, Robert-Koch Str. 41, 48149 Münster, Germany. Phone: 49-251-8352216. Fax: 49-251-8357175. E-mail:
mbiela{at}uni-muenster.de.

Editor: A. D. O'Brien

REFERENCES
1 - Albert, M. J., S. M. Faruque, A. S. G. Faruque, K. A. Bettelheim, P. K. B. Neogi, N. A. Bhuian, and J. B. Kaper. 1996. Controlled study of cytolethal distending toxin-producing Escherichia coli infections in Bangladeshi children. J. Clin. Microbiol. 34:717-719.[Abstract]
2 - Ansaruzzaman, M., M. J. Albert, S. Nahar, R. Byun, M. Katouli, I. Kuhn, and R. Mölby. 2000. Clonal groups of enteropathogenic Escherichia coli isolated in case-control studies of diarrhoea in Bangladesh. J. Med. Microbiol. 49:177-185.[Abstract/Free Full Text]
3 - Boerlin, P., S. A. McEwen, F. Boerlin-Petzold, J. B. Wilson, B. J. Johnson, and C. L. Gyles. 1999. Association between virulence factors of Shiga toxin-producing Escherichia coli and disease in humans. J. Clin. Microbiol. 37:497-503.[Abstract/Free Full Text]
4 - Clark, C. G., S. T. Johnson, R. H. Easy, J. L. Campbell, and F. G. Rodgers. 2002. PCR for detection of cdt-III and the relative frequencies of cytolethal distending toxin variant-producing Escherichia coli isolates from humans and cattle. J. Clin. Microbiol. 40:2671-2674.[Abstract/Free Full Text]
5 - Cortes-Bratti, X., T. Frisan, and M. Thelestam. 2001. The cytolethal distending toxins induce DNA damage and cell cycle arrest. Toxicon 39:1729-1736.[Medline]
6 - Elwell, C. A., and L. A. Dreyfus. 2000. DNase I homologous residues in CdtB are critical for cytolethal distending toxin-mediated cell cycle arrest. Mol. Microbiol. 37:952-963.[CrossRef][Medline]
7 - Friedrich, A. W., M. Bielaszewska, W.-L. Zhang, M. Pulz, T. Kuczius, A. Ammon, and H. Karch. 2002. Escherichia coli harboring Shiga toxin 2 gene variants: frequency and association with clinical symptoms. J. Infect. Dis. 185:74-84.[CrossRef][Medline]
8 - Friedrich, A. W., J. Borell, M. Bielaszewska, A. Fruth, H. Tschäpe, and H. Karch. 2003. Shiga toxin 1c-producing Escherichia coli strains: phenotypic and genetic characterization and association with human disease. J. Clin. Microbiol. 41:2448-2453.[Abstract/Free Full Text]
9 - Ghilardi, A. C. R., T. A. T. Gomes, and L. R. Trabulsi. 2001. Production of cytolethal distending toxin and other virulence characteristics of Escherichia coli strains of serogroup O86. Mem. Inst. Oswaldo Cruz. 96:703-707.[Medline]
10 - Ito, H., A. Terai, H. Kurazono, Y. Takeda, and M. Nishibuchi. 1990. Cloning and nucleotide sequencing of Vero toxin 2 variant genes from Escherichia coli O91:H21 isolated from a patient with the hemolytic uremic syndrome. Microb. Pathog. 8:47-60.[CrossRef][Medline]
11 - Janka, A., M. Bielaszewska, U. Dobrindt, L. Greune, M. A. Schmidt, and Helge Karch. 2003. The cytolethal distending toxin (cdt) gene cluster in enterohemorrhagic Escherichia coli O157:H- and O157:H7: characterization and evolutionary considerations. Infect. Immun. 71:3634-3638.[Abstract/Free Full Text]
12 - Johnson, J. R., E. Oswald, T. T. O'Bryan, M. A. Kuskowski, and L. Spandjaard. 2002. Phylogenetic distribution of virulence-associated genes among Escherichia coli isolates associated with neonatal meningitis in the Netherlands. J. Infect. Dis. 185:774-784.[CrossRef][Medline]
13 - Johnson, W. M., and H. Lior. 1988. A new heat-labile cytolethal distending toxin (CLDT) produced by Escherichia coli isolates from clinical material. Microb. Pathog. 4:103-113.[CrossRef][Medline]
14 - Lara-Tejero, M., and J. E. Galan. 2000. A bacterial toxin that controls cell cycle progression as a deoxyribonuclease I-like protein. Science 290:354-357.[Abstract/Free Full Text]
15 - Lara-Tejero, M., and J. E. Galan. 2001. CdtA, CdtB, and CdtC form a tripartite complex that is required for cytolethal distending toxin activity. Infect. Immun. 69:4358-4365.[Abstract/Free Full Text]
16 - Lee, R. B., D. C. Hassane, D. L. Cottle, and C. L. Pickett. 2003. Interactions of Campylobacter jejuni cytolethal distending toxin subunits CdtA and CdtC with HeLa cells. Infect. Immun. 71:4883-4890.[Abstract/Free Full Text]
17 - Macrina, F. L., D. J. Kopecko, K. R. Jones, D. J. Ayers, and S. M. McCowen. 1978. A multiple plasmid-containing Escherichia coli strain: convenient source of size reference plasmid molecules. Plasmid 1:417-420.[CrossRef][Medline]
18 - Paton, A. W., M. C. Woodrow, R. M. Doyle, J. A. Lanser, and J. C. Paton. 1999. Molecular characterization of a Shiga-toxigenic Escherichia coli O113:H21 strain lacking eae responsible for a cluster of cases of hemolytic-uremic syndrome. J. Clin. Microbiol. 37:3357-3361.[Abstract/Free Full Text]
19 - Peres, S. P., O. Marches, F. Daigle, J. P. Nougayrede, F. Herault, C. Tasca, J. DeRycke, and E. Oswald. 1997. A new cytolethal distending toxin (CDT) from Escherichia coli producing CNF2 blocks HeLa cell division in G2/M phase. Mol. Microbiol. 24:1095-1107.[CrossRef][Medline]
20 - Pickett, C. L., D. L. Cottle, E. C. Pesci, and G. Bikah. 1994. Cloning, sequencing, and expression of the Escherichia coli cytolethal distending toxin genes. Infect. Immun. 62:1046-1051.[Abstract/Free Full Text]
21 - Prager, R., U. Strutz, A. Fruth, and H. Tschape. 2003. Subtyping of pathogenic Escherichia coli strains using flagellar H- antigens: serotyping versus fliC polymorphisms. Int. J. Med. Microbiol. 292:477-486.[CrossRef][Medline]
22 - Scott, D. A., and J. B. Kaper. 1994. Cloning and sequencing of the genes encoding Escherichia coli cytolethal distending toxin. Infect. Immun. 62:244-251.[Abstract/Free Full Text]
23 - Tietze, E., and H. Tschäpe. 1983. Plasmid pattern analysis of natural bacterial isolates and its epidemiological implication. J. Hyg. (Cambridge) 90:475-488.
24 - Toth, I., F. Herault, L. Beutin, and E. Oswald. 2003. Production of cytolethal distending toxins by pathogenic Escherichia coli isolated from human and animal sources: Establishment of the existence of a new cdt variant (type IV). J. Clin. Microbiol. 41:4285-4291.[Abstract/Free Full Text]
Infection and Immunity, March 2004, p. 1812-1816, Vol. 72, No. 3
0019-9567/04/$08.00+0 DOI: 10.1128/IAI.72.3.1812-1816.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Bielaszewska, M., Stoewe, F., Fruth, A., Zhang, W., Prager, R., Brockmeyer, J., Mellmann, A., Karch, H., Friedrich, A. W.
(2009). Shiga Toxin, Cytolethal Distending Toxin, and Hemolysin Repertoires in Clinical Escherichia coli O91 Isolates. J. Clin. Microbiol.
47: 2061-2066
[Abstract]
[Full Text]
-
Highet, A. R., Berry, A. M., Bettelheim, K. A., Goldwater, P. N.
(2009). The frequency of molecular detection of virulence genes encoding cytolysin A, high-pathogenicity island and cytolethal distending toxin of Escherichia coli in cases of sudden infant death syndrome does not differ from that in other infant deaths and healthy infants. J Med Microbiol
58: 285-289
[Abstract]
[Full Text]
-
Bielaszewska, M., Prager, R., Vandivinit, L., Musken, A., Mellmann, A., Holt, N. J., Tarr, P. I., Karch, H., Zhang, W.
(2009). Detection and Characterization of the Fimbrial sfp Cluster in Enterohemorrhagic Escherichia coli O165:H25/NM Isolates from Humans and Cattle. Appl. Environ. Microbiol.
75: 64-71
[Abstract]
[Full Text]
-
Toth, I., Nougayrede, J.-P., Dobrindt, U., Ledger, T. N., Boury, M., Morabito, S., Fujiwara, T., Sugai, M., Hacker, J., Oswald, E.
(2009). Cytolethal Distending Toxin Type I and Type IV Genes Are Framed with Lambdoid Prophage Genes in Extraintestinal Pathogenic Escherichia coli. Infect. Immun.
77: 492-500
[Abstract]
[Full Text]
-
Asakura, M., Hinenoya, A., Alam, M. S., Shima, K., Zahid, S. H., Shi, L., Sugimoto, N., Ghosh, A. N., Ramamurthy, T., Faruque, S. M., Nair, G. B., Yamasaki, S.
(2007). An inducible lambdoid prophage encoding cytolethal distending toxin (Cdt-I) and a type III effector protein in enteropathogenic Escherichia coli. Proc. Natl. Acad. Sci. USA
104: 14483-14488
[Abstract]
[Full Text]
-
Wang, W., Perepelov, A. V., Feng, L., Shevelev, S. D., Wang, Q., Senchenkova, S. N., Han, W., Li, Y., Shashkov, A. S., Knirel, Y. A., Reeves, P. R., Wang, L.
(2007). A group of Escherichia coli and Salmonella enterica O antigens sharing a common backbone structure. Microbiology
153: 2159-2167
[Abstract]
[Full Text]
-
Gyles, C. L.
(2007). Shiga toxin-producing Escherichia coli: An overview. J ANIM SCI
85: E45-E62
[Abstract]
[Full Text]
-
Orth, D., Grif, K., Dierich, M. P., Wurzner, R.
(2006). Cytolethal distending toxins in Shiga toxin-producing Escherichia coli: alleles, serotype distribution and biological effects.. J Med Microbiol
55: 1487-1492
[Abstract]
[Full Text]
-
Friedrich, A. W., Lu, S., Bielaszewska, M., Prager, R., Bruns, P., Xu, J.-G., Tschape, H., Karch, H.
(2006). Cytolethal Distending Toxin in Escherichia coli O157:H7: Spectrum of Conservation, Structure, and Endothelial Toxicity.. J. Clin. Microbiol.
44: 1844-1846
[Abstract]
[Full Text]
-
Sonntag, A.-K., Bielaszewska, M., Mellmann, A., Dierksen, N., Schierack, P., Wieler, L. H., Schmidt, M. A., Karch, H.
(2005). Shiga Toxin 2e-Producing Escherichia coli Isolates from Humans and Pigs Differ in Their Virulence Profiles and Interactions with Intestinal Epithelial Cells. Appl. Environ. Microbiol.
71: 8855-8863
[Abstract]
[Full Text]
-
Bielaszewska, M., Zhang, W., Tarr, P. I., Sonntag, A.-K., Karch, H.
(2005). Molecular Profiling and Phenotype Analysis of Escherichia coli O26:H11 and O26:NM: Secular and Geographic Consistency of Enterohemorrhagic and Enteropathogenic Isolates. J. Clin. Microbiol.
43: 4225-4228
[Abstract]
[Full Text]
-
Creuzburg, K., Kohler, B., Hempel, H., Schreier, P., Jacobs, E., Schmidt, H.
(2005). Genetic structure and chromosomal integration site of the cryptic prophage CP-1639 encoding Shiga toxin 1. Microbiology
151: 941-950
[Abstract]
[Full Text]
-
Hyma, K. E., Lacher, D. W., Nelson, A. M., Bumbaugh, A. C., Janda, J. M., Strockbine, N. A., Young, V. B., Whittam, T. S.
(2005). Evolutionary Genetics of a New Pathogenic Escherichia Species: Escherichia albertii and Related Shigella boydii Strains. J. Bacteriol.
187: 619-628
[Abstract]
[Full Text]
-
Bielaszewska, M., Sinha, B., Kuczius, T., Karch, H.
(2005). Cytolethal Distending Toxin from Shiga Toxin-Producing Escherichia coli O157 Causes Irreversible G2/M Arrest, Inhibition of Proliferation, and Death of Human Endothelial Cells. Infect. Immun.
73: 552-562
[Abstract]
[Full Text]