First-Time Isolation and Characterization of a Bacteriophage Encoding the Shiga Toxin 2c Variant, Which Is Globally Spread in Strains of
            <i>Escherichia coli</i>
            O157

Strauch, Eckhard; Schaudinn, Christoph; Beutin, Lothar

doi:10.1128/iai.72.12.7030-7039.2004

Cited by 32 publications

(33 citation statements)

References 52 publications

(71 reference statements)

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“…It differs from the prototypical Stx2a-encoding phages BP-933W in its chromosomal integration site, phage morphology, and superinfection immunity (43,44). The Stx2c prophage found in lineage I/II strains (i.e., EC4115) have gene content and architecture similar to phage 2851 (23).…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Stx2-Encoding Prophage in Persistent Bovine Escherichia coli O157:H7 Strains

Park

Stanton

Ciezki

et al. 2013

Appl Environ Microbiol

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e Escherichia coli O157:H7 is a human pathogen that resides asymptomatically in its bovine host. The level of Shiga toxin (Stx) produced is variable in bovine-derived strains in contrast to human isolates that mostly produce high levels of Stx. To understand the genetic basis for varied Stx production, chronological collections of bovine isolates from Wisconsin dairy farms, R and X, were analyzed for multilocus prophage polymorphisms, stx 2 subtypes, and the levels of stx 2 transcript and toxin. The E. coli O157:H7 that persisted on both farms were phylogenetically distinct and yet produced little to no Stx2 due to gene deletions in Stx2c-encoding prophage (farm R) or insertional inactivation of stx 2a by IS1203v (farm X). Loss of key regulatory and lysis genes in Stx2c-encoding prophage abolished stx 2c transcription and induction of the prophage and stx 2a ::IS1203v in Stx2a-encoding prophage generated a truncated stx 2a mRNA without affecting phage production. Stx2-producing strains were transiently present (farm R) and became Stx2 negative on farm X (i.e., stx 2a ::IS1203v). To our knowledge, this is the first study that details the evolution of E. coli O157:H7 and its Stx2-encoding prophage in a chronological collection of natural isolates. The data suggest the bovine and farm environments can be niches where Stx2-negative E. coli O157:H7 emerge and persist, which explains the Stx variability in bovine isolates and may be part of an evolutionary step toward becoming bovine specialists.

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Section: Discussionmentioning

confidence: 99%

Evolution of the Stx2-Encoding Prophage in Persistent Bovine Escherichia coli O157:H7 Strains

Park

Stanton

Ciezki

et al. 2013

Appl Environ Microbiol

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“…Multiplex PCR was used to detect stx2c and the Stx2c-phage o and q genes (39) in 519 strains; stx data were missing for 19 strains, four of which were repeatedly stx-negative. The malate dehydrogenase (mdh) gene was used as a positive control.…”

Section: Methodsmentioning

confidence: 99%

“…5). Interestingly, the Sakai and EDL-933 genomes are more similar to each other in gene content and nucleotide sequence identity than to the clade 8 spinach outbreak strain, which carries additional genetic material including stx2c and the Stx2c lysogenic bacteriophage 2851 (39). This suggests that the spinach outbreak genome and, by inference, clade 8, has substantial time to diverge with respect to its genetic composition when compared with strains from other lineages.…”

Section: Figmentioning

confidence: 99%

Variation in virulence among clades of Escherichia coli O157:H7 associated with disease outbreaks

Manning

Motiwala

Springman

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

410

612

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Escherichia coli O157:H7, a toxin-producing food and waterborne bacterial pathogen, has been linked to large outbreaks of gastrointestinal illness for more than two decades. E. coli O157 causes a wide range of clinical illness that varies by outbreak, although factors that contribute to variation in disease severity are poorly understood. Several recent outbreaks involving O157 contamination of fresh produce (e.g., spinach) were associated with more severe disease, as defined by higher hemolytic uremic syndrome and hospitalization frequencies, suggesting that increased virulence has evolved. To test this hypothesis, we developed a system that detects SNPs in 96 loci and applied it to >500 E. coli O157 clinical strains. Phylogenetic analyses identified 39 SNP genotypes that differ at 20% of SNP loci and are separated into nine distinct clades. Differences were observed between clades in the frequency and distribution of Shiga toxin genes and in the type of clinical disease reported. Patients with hemolytic uremic syndrome were significantly more likely to be infected with clade 8 strains, which have increased in frequency over the past 5 years. Genome sequencing of a spinach outbreak strain, a member of clade 8, also revealed substantial genomic differences. These findings suggest that an emergent subpopulation of the clade 8 lineage has acquired critical factors that contribute to more severe disease. The ability to detect and rapidly genotype O157 strains belonging to such lineages is important and will have a significant impact on both disease diagnosis and treatment guidelines.pathogens ͉ polymorphisms ͉ population genetics E nterohemorrhagic Escherichia coli (EHEC) includes a diverse population of Shiga toxin-producing E. coli that causes outbreaks of food and waterborne disease (1-3). EHEC often resides in bovine reservoirs and is transmitted via many food vehicles including cooked meat, such as hamburger (4) and salami (5), and raw vegetables, such as lettuce (6, 7) and spinach (8). In North America, E. coli O157:H7 is the most common EHEC serotype contributing to Ͼ75,000 human infections (9) and 17 outbreaks (3) per year.It is not clear why outbreaks of EHEC O157 vary dramatically in the severity of illness and the frequency of the most serious complication, hemolytic uremic syndrome (HUS) (10-12). The 1993 outbreak in western North America (4) and the large 1996 outbreak in Japan (13) had low rates of hospitalization and HUS (14, 15), whereas the 2006 North American spinach outbreak (8) had high rates of both hospitalization (Ͼ50%) and HUS (Ͼ10%). One hypothesis is that outbreak strains differ in virulence as a result of variation in the presence and expression of different Shiga toxin (Stx) gene combinations (16)(17)(18)(19).To assess the genetic diversity and variability in virulence among E. coli O157 strains, we developed a real-time PCR system for identifying synonymous and nonsynonymous mutations as SNPs (20-23). Although molecular subtyping methods, such as pulsedfield gel electrophoresis (PFGE), ...

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“…Primers developed by Lin et al (30) give in the case of the stx 2c allele a product of 903 bp, which can be distinguished from the stx 2 gene by a HincII digestion. Such PCR-restriction fragment length polymorphism (RFLP) investigations revealed that stx 1 and stx 2c as well as stx 2 and stx 2c are frequently associated in O157:H7 and strains encoding only Stx2c are more rarely isolated (6,48,52). While Stx1 and Stx2 are disseminated over a large variety of STEC serotypes, the Stx2c type was found to be restricted mostly to STEC serotype O157:H7 and, moreover, to certain clonal lineages of that serotype (54); however, the reasons for this finding are not known.…”

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confidence: 99%

Bacteriophage 2851 Is a Prototype Phage for Dissemination of the Shiga Toxin Variant Gene 2c in Escherichia coli O157:H7

et al. 2008

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and Stx2, are produced in STEC O157. Variants of the Stx2 type (Stx2, Stx2c) are associated with high virulences of these strains for humans. A bacteriophage designated 2851 from a human STEC O157 encoding the Stx2c variant was described previously. Nucleotide sequence analysis of the phage 2851 genome revealed 75 predicted coding sequences and indicated a mosaic structure typical for lambdoid phages. Analyses of free phages and K-12 phage 2851 lysogens revealed that upon excision from the bacterial chromosome, the loss of a phage-encoded IS629 element leads to fusion of phage antA and antB genes, with the generation of a recombined antAB gene encoding a strong antirepressor. In wild-type E. coli O157 as well as in K-12 strains, phage 2851 was found to be integrated in the sbcB locus. Additionally, phage 2851 carries an open reading frame which encodes an OspB-like type III effector similar to that found in Shigella spp. Investigation of 39 stx 2c E. coli O157 strains revealed that all except 1 were positive for most phage 2851-specific genes and possessed a prophage with the same border sequences integrated into the sbcB locus. Phage 2851-specific sequences were absent from most stx 2c -negative E. coli O157 strains, and we suggest that phage 2851-like phages contributed significantly to the dissemination of the Stx2c variant toxin within this group of E. coli.

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First-Time Isolation and Characterization of a Bacteriophage Encoding the Shiga Toxin 2c Variant, Which Is Globally Spread in Strains of Escherichia coli O157

Cited by 32 publications

References 52 publications

Evolution of the Stx2-Encoding Prophage in Persistent Bovine Escherichia coli O157:H7 Strains

Evolution of the Stx2-Encoding Prophage in Persistent Bovine Escherichia coli O157:H7 Strains

Variation in virulence among clades of Escherichia coli O157:H7 associated with disease outbreaks

Bacteriophage 2851 Is a Prototype Phage for Dissemination of the Shiga Toxin Variant Gene 2c in Escherichia coli O157:H7

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