Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among
            <i>Escherichia coli</i>
            O157:H7 Isolates from Cattle than in Those from Humans

Besser, Thomas E.; Shaikh, Nurmohammad; Holt, Nicholas J.; Tarr, Phillip I.; Konkel, Michael E.; Malik-Kale, Preeti; Walsh, Coilin W.; Whittam, Thomas S.; Bono, James L.

doi:10.1128/aem.01035-06

Cited by 100 publications

(136 citation statements)

References 37 publications

Supporting

Mentioning

124

Contrasting

Order By: Relevance

“…Evolutionary changes in the clade 8 subpopulation could explain its emergence in several recent foodborne outbreaks; however, it is not clear why this virulent subpopulation is increasing in prevalence. Because humans are more an incidental host for EHEC O157, further investigation of the bovine reservoir (48,49) and environment is critical, as is the evaluation of agricultural practices in areas where livestock and produce are farmed side by side. Identifying the underlying factors that lead to enhanced virulence and the successful transmission of EHEC O157 in contaminated food and water is imperative.…”

Section: Discussionmentioning

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.

Self Cite

406

612

View full text Add to dashboard Cite

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), ...

show abstract

Section: Discussionmentioning

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.

Self Cite

406

612

View full text Add to dashboard Cite

show abstract

“…Cluster 1's founder backbone concatenome sequence (unlike the founder backbone concatenome sequence of cluster 3) is deduced with near certainty because we know ancestral and descendant sequence. Unlike cluster 2, cluster 1 is common among contemporaneous pathogens (15). Because cluster 1 O157:H7s have been in existence for several millennia, ample time has presumably elapsed for its members to have radiated on multiple branches from their founder.…”

Section: Discussionmentioning

confidence: 99%

A precise reconstruction of the emergence and constrained radiations of Escherichia coli O157 portrayed by backbone concatenomic analysis

Leopold

Magrini

Holt

et al. 2009

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

Self Cite

111

150

View full text Add to dashboard Cite

Single nucleotide polymorphisms (SNPs) in stable genome regions provide durable measurements of species evolution. We systematically identified each SNP in concatenations of all backbone ORFs in 7 newly or previously sequenced evolutionarily instructive pathogenic Escherichia coli O157:H7, O157:H ؊ , and O55:H7. The 1,113 synonymous SNPs demonstrate emergence of the largest cluster of this pathogen only in the last millennium. Unexpectedly, shared SNPs within circumscribed clusters of organisms suggest severely restricted survival and limited effective population sizes of pathogenic O157:H7, tenuous survival of these organisms in nature, source-sink evolutionary dynamics, or, possibly, a limited number of mutations that confer selective advantage. A single large segment spanning the rfb-gnd gene cluster is the only backbone region convincingly acquired by recombination as O157 emerged from O55. This concatenomic analysis also supports using SNPs to differentiate closely related pathogens for infection control and forensic purposes. However, constrained radiations raise the possibility of making false associations between isolates.E. coli ͉ evolution ͉ SNPs

show abstract

“…Considering the stx phages present in E. coli O157 : H7 strains, two insertion sites were first described as preferred: wrbA and yehV (Shaikh & Tarr, 2003;Besser et al, 2007). However, there are other integration sites described for stx phages in O157, such as sbcB, argW and yecE (De Greve et al, 2002;Mellor et al, 2012;Shringi et al, 2012).…”

Section: Insertion Site Diversitymentioning

confidence: 99%

Shiga toxins and stx phages: highly diverse entities

2015

View full text Add to dashboard Cite

Shiga toxins are the main virulence factors of a group of Escherichia coli strains [Shiga toxinproducing E. coli (STEC)] that cause severe human diseases, such as haemorrhagic colitis and haemolytic-uraemic syndrome. The Shiga toxin family comprises several toxin subtypes, which have been differentially related to clinical manifestations. In addition, the phages that carry the Shiga toxin genes (stx phages) are also diverse. These phages play an important role not only in the dissemination of Shiga toxin genes and the emergence of new STEC strains, but also in the regulation of Shiga toxin production. Consequently, differences in stx phages may affect the dissemination of stx genes as well as the virulence of STEC strains. In addition to presenting an overview of Shiga toxins and stx phages, in this review we highlight current knowledge about the diversity of stx phages, with emphasis on its impact on STEC virulence. We consider that this diversity should be taken into account when developing STEC infection treatments and diagnostic approaches, and when conducting STEC control in reservoirs.

show abstract

Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among Escherichia coli O157:H7 Isolates from Cattle than in Those from Humans

Cited by 100 publications

References 37 publications

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

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

A precise reconstruction of the emergence and constrained radiations of Escherichia coli O157 portrayed by backbone concatenomic analysis

Shiga toxins and stx phages: highly diverse entities

Contact Info

Product

Resources

About