Multilocus Genotype Analysis of Escherichia coli O157 Isolates from Australia and the United States Provides Evidence of Geographic Divergence

Mellor, Glen E.; Besser, Thomas E.; Davis, Margaret A.; Beavis, B.; Jung, Woo Kyung; Smith, Helen; Jennison, Amy V.; Doyle, Christine J.; Chandry, P. Scott; Gobius, Kari S.; Fegan, Narelle

doi:10.1128/aem.01525-13

Cited by 46 publications

(54 citation statements)

References 53 publications

(102 reference statements)

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“…Comparisons of lineage and tir SNP data revealed that tir (255A) was more associated with lineage II, while tir (255T) was associated at higher frequency with lineage I/II. A similar correlation between LSPA-6 and tir (A255T) has been reported in other studies (Arthur et al, 2013;Mellor et al, 2013), suggesting that tir (A255T) might be used as a useful predictor of lineage and as a promising indicator for potential pathogenic strains. Future experiments should be directed to analyse strains harbouring different alleles at position 255 of the tir gene for human intestinal colonization.…”

Section: Discussionsupporting

confidence: 58%

“…This analysis has been suggested to be crucial in monitoring different genotypes that might confer a high risk for virulence and/or transmission potential to humans (Mellor et al, 2013). Characterization of lineage types among E. coli O157 : H7 strains in Belgium revealed higher prevalence of lineage I/II among E. coli O157 : H7 strains analysed (70.6 %).…”

Section: Discussionmentioning

confidence: 99%

“…This gene encodes a translocated intimin receptor that mediates adhesion to mammalian cells and the formation of attaching and effacing (A/E) lesions through binding to intimin (Kaper et al, 2004). Some investigators previously suggested that tir (255T) harbouring strains are more virulent in humans than tir (255A) harbouring strains Franz et al, 2012;Mellor et al, 2013). Shiga toxin bacteriophage insertion (SBI) site analysis relies on amplification of the stx toxin genes (stx 1 and stx 2 ) and the insertion site junctions of their encoding bacteriophages that can be used as a valuable genotyping technique to distinguish E. coli O157 : H7 strains, based on their distribution, gene expression and virulence potential (Besser et al, 2008;Shaikh & Tarr, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

et al. 2015

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The aim of this study was to identify an epidemiological association between Shiga toxinproducing Escherichia coli O157 : H7 strains associated with human infection and with food sources. Frequency distributions of different genetic markers of E. coli O157 : H7 strains recovered from human and food sources were compared using molecular assays to identify E. coli O157 : H7 genotypes associated with variation in pathogenic potential and host specificity. Genotypic characterization included: lineage-specific polymorphism assay (LSPA-6), clade typing, tir (A255T) polymorphism, Shiga toxin-encoding bacteriophage insertion site analysis and variant analysis of Shiga toxin 2 gene (stx 2a and stx 2c ) and antiterminator Q genes (Q 933 and Q 21 ). The intermediate lineage (LI/II) dominated among both food and human strains. Compared to other clades, clades 7 and 8 were more frequent among food and human strains, respectively. The tir (255T) polymorphism occurred more frequently among human strains than food strains. Q 21 and Q 933+Q21 were found at significantly higher frequencies among food and human strains, respectively. Moreover, stx 2a and stx 2a+c were detected at significantly higher frequencies among human strains compared to food strains. Bivariate analysis revealed significant concordance (P,0.05) between the LSPA-6 assay and the other typing methods. Multivariable regression Abbreviations: HP, hairpin; HUS, haemolytic uraemic syndrome; LSPA-6, lineage-specific polymorphism assay; SBI, Shiga toxin bacteriophage insertion; STEC, Shiga toxin-producing Escherichia coli; stx 1 , Shiga toxin 1; stx 2 , Shiga toxin 2.Five supplementary tables are available with the online Supplementary Material.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

et al. 2015

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“…Although there are 10 described subtypes of stx1 and stx2 combined (3), in an examination of 444 strains covering a wide temporal spread and range of phage types, only three subtypes (stx2a, stx2c and stx1a) were observed. Previous studies examining strains from cattle and humans similarly found only stx2a, stx2c and stx1a (22). The most diverse stx identified here was stx2a, followed by stx1a and then stx2c (Figures 4-6).…”

Section: Discussionmentioning

confidence: 68%

Insight into Shiga toxin genes encoded by Escherichia coli O157 from whole genome sequencing

Ashton

Perry

Ellis

et al. 2014

Preprint

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The ability of Shiga toxin-producing Escherichia coli (STEC) to cause severe illness in humans is determined by multiple host factors and bacterial characteristics, including Shiga toxin (Stx) subtype. Given the link between Stx2a subtype and disease severity, we sought to identify the stx subtypes present in whole genome sequences (WGS) of 444 isolates of STEC O157. Difficulties in assembling the stx genes in some strains, were overcome by using two complementary bioinformatics methods; mapping and de novo assembly. We compared the WGS analysis with the results obtained using a PCR approach and investigated the diversity within and between the subtypes. All strains of STEC O157 in this study had stx1a, stx2a or stx2c or a combination of these three genes. There was over 99% (442/444) concordance between PCR and WGS. When common source strains were excluded, 236/349 strains of STEC O157 had multiple copies of different Stx subtypes and 54 had multiple copies of the same Stx subtype. Of those strains harbouring multiple copies of the same Stx subtype, 33 had variants between the alleles while 21 had identical copies. Strains harbouring Stx2a only were most commonly found to have multiple alleles of the same subtype (42%). Both the PCR and WGS approach to stx subtyping provided a good level of sensitivity and specificity. In addition, the WGS data also showed there were a significant proportion of strains harbouring multiple alleles of the same Stx subtype associated with clinical disease in England. PrePrints AbstractThe ability of Shiga toxin-producing Escherichia coli (STEC) to cause severe illness in humans is determined by multiple host factors and bacterial characteristics, including Shiga toxin (Stx) subtype. Given the link between Stx2a subtype and disease severity, we sought to identify the stx subtypes present in whole genome sequences (WGS) of 444 isolates of STEC O157. Difficulties in assembling the stx genes in some strains, were overcome by using two complementary bioinformatics methods; mapping and de novo assembly. We compared the WGS analysis with the results obtained using a PCR approach and investigated the diversity within and between the subtypes. All strains of STEC O157 in this study had stx1a, stx2a or stx2c or a combination of these three genes. There was over 99% (442/444) concordance between PCR and WGS. When common source strains were excluded, 236/349 strains of STEC O157 had multiple copies of different Stx subtypes and 54 had multiple copies of the same Stx subtype. Of those strains harbouring multiple copies of the same Stx subtype, 33 had variants between the alleles while 21 had identical copies. Strains harbouring Stx2a only were most commonly found to have multiple alleles of the same subtype (42%). Both the PCR and WGS approach to stx subtyping provided a good level of sensitivity and specificity. In addition, the WGS data also showed there were a significant proportion of strains harbouring multiple alleles of the same Stx subtype associated with clinical disease in England.

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“…Therefore, rapid and accurate detection of this toxin (stx2) in food is very important in preventing STEC infections (24)(25)(26)(27).…”

Section: Similar Results Have Been Reported From Iran By Akhi Et Al (mentioning

confidence: 99%

The frequency of shiga-like toxin (stx1 and stx2) and EHEC-hlyA in food by multiplex PCR

Önlen

Duran

Bayraktar

et al. 2017

Revista Romana De Medicina De Laborator

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Multilocus Genotype Analysis of Escherichia coli O157 Isolates from Australia and the United States Provides Evidence of Geographic Divergence

Cited by 46 publications

References 53 publications

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources

Insight into Shiga toxin genes encoded by Escherichia coli O157 from whole genome sequencing

The frequency of shiga-like toxin (stx1 and stx2) and EHEC-hlyA in food by multiplex PCR

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