Variation in Stress Resistance Patterns among
            <i>stx</i>
            Genotypes and Genetic Lineages of Shiga Toxin-Producing Escherichia coli O157

Lee, Ken-ichi; French, Nigel P.; Jones, Geoff; Hara-Kudo, Yukiko; Iyoda, Sunao; Kobayashi, Hideki; Sugita-Konishi, Yoshiko; Tsubone, Hirokazu; Kumagai, Shinya

doi:10.1128/aem.06646-11

Cited by 25 publications

(22 citation statements)

References 41 publications

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“…This result suggests a relatively narrow phylogenetic lineage for the 026 strains included in this study. Low variability in heat resistance between closely related E. coli 0157:H7 strains has been reported previously (31). These results indicate that the selection of E. coli strains in pressure and heat resistance studies cannot be extrapolated from the serotypes or phylogenetic groups.…”

Section: Discussionmentioning

confidence: 59%

Variation in Heat and Pressure Resistance of Verotoxigenic and Nontoxigenic Escherichia coli

Liu¹,

Gill²,

McMullen³

et al. 2015

Journal of Food Protection

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This study evaluated the heat and pressure resistance of 112 strains of Escherichia coli, including 102 strains of verotoxigenic E. coli (VTEC) representing 23 serotypes and four phylogenetic groups. In an initial screening, the heat and pressure resistance of 100 strains, including 94 VTEC strains, were tested in phosphate-buffered saline (PBS). Treatment at 60°C for 5 min reduced cell counts by 2.0 to 5.5 log CFU/ml; treatment at 600 MPa for 3 min at 25°C reduced the cell counts by 1.1 to 5.5 log CFU/ml. Heat or pressure resistance did not correlate to the phylogenetic group or the serotype. A smaller group of E. coli strains was evaluated for heat and pressure resistance in Luria-Bertani (LB) broth. Generally, the levels of heat resistance of E. coli strains in LB and PBS were similar; however, the levels of pressure resistance observed for treatments in LB broth or PBS were variable. The cell counts of pressure-resistant strains of VTEC were reduced by less than 1.5 log CFU/ml after treatment at 600 MPa for 3 min. E. coli strains were also treated with 600 MPa for 3 min in ground beef or inoculated into beef patties and grilled to 63 or 71°C. The cell counts of the VTEC E. coli O26:H11 strain 05-6544 were reduced by 2 log CFU/g by pressure treatment in ground beef. The cell counts of the heat-resistant E. coli strain AW1.7 were reduced by 1.4 and 3.4 log CFU/g in beef patties grilled to internal temperatures of 63 and 71°C, respectively. The cell counts of E. coli 05-6544 were reduced by less than 3 and 6 log CFU/g in beef patties grilled to internal temperatures of 63 and 71°C, respectively. To study whether the composition of the beef patties influenced heat resistance, E. coli strains AW1.7, AW1.7 Δ pHR1, MG1655, and LMM1030 were mixed into beef patties containing 15 or 35% fat and 0 or 2% NaCl, and the patties were grilled to an internal temperature of 63°C. The highest heat resistance of E. coli was observed in patties containing 15% fat and 2% NaCl.

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Section: Discussionmentioning

confidence: 59%

Variation in Heat and Pressure Resistance of Verotoxigenic and Nontoxigenic Escherichia coli

Liu¹,

Gill²,

McMullen³

et al. 2015

Journal of Food Protection

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“…The human isolates, predominantly LSPA-6 lineage I or I/II, typically carried stx2a alone or in combination with stx1 or stx2c while LSPA-6 lineage II cattle isolates carried stx2c alone or in combination with stx1 [38]. These investigators also demonstrated that lineage I ( stx1 - stx2 ) isolates showed multiple stress resistances when compared to the lineage II ( stx1 - stx2c ) genotypes [39].…”

Section: Discussionmentioning

confidence: 94%

Carriage of stx2a Differentiates Clinical and Bovine-Biased Strains of Escherichia coli O157

et al. 2012

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BackgroundShiga toxin (Stx) are cardinal virulence factors of enterohemorrhagic E. coli O157:H7 (EHEC O157). The gene content and genomic insertion sites of Stx-associated bacteriophages differentiate clinical genotypes of EHEC O157 (CG, typical of clinical isolates) from bovine-biased genotypes (BBG, rarely identified among clinical isolates). This project was designed to identify bacteriophage-mediated differences that may affect the virulence of CG and BBG.MethodsStx-associated bacteriophage differences were identified by whole genome optical scans and characterized among >400 EHEC O157 clinical and cattle isolates by PCR.ResultsOptical restriction maps of BBG strains consistently differed from those of CG strains only in the chromosomal insertion sites of Stx2-associated bacteriophages. Multiplex PCRs (stx1, stx2a, and stx2c as well as Stx-associated bacteriophage - chromosomal insertion site junctions) revealed four CG and three BBG that accounted for >90% of isolates. All BBG contained stx2c and Stx2c-associated bacteriophage – sbcB junctions. All CG contained stx2a and Stx2a-associated bacteriophage junctions in wrbA or argW.ConclusionsPresence or absence of stx2a (or another product encoded by the Stx2a-associated bacteriophage) is a parsimonious explanation for differential virulence of BBG and CG, as reflected in the distributions of these genotypes in humans and in the cattle reservoir.

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“…Lineages defined by LSAP-6 were used to demonstrate differences in pathogenicity among different lineage strains (Dowd and Williams, 2008). However, there are some discrepancies in the interpretation of LSPA-6 codes in terms of lineages in previous descriptions (Franz et al, 2012;Lee et al, 2012;Sharma et al, 2009;Whitworth et al, 2010;Yokoyama et al, 2011b). Manning et al (2008) proposed the clade phylogenetic groups as defined by SNP analysis.…”

Section: Introductionmentioning

confidence: 99%

Clade analysis of enterohemorrhagic Escherichia coli serotype O157:H7/H- strains and hierarchy of their phylogenetic relationships

Yokoyama

Hirai

Hashimoto

et al. 2012

Infection, Genetics and Evolution

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Variation in Stress Resistance Patterns among stx Genotypes and Genetic Lineages of Shiga Toxin-Producing Escherichia coli O157

Cited by 25 publications

References 41 publications

Variation in Heat and Pressure Resistance of Verotoxigenic and Nontoxigenic Escherichia coli

Variation in Heat and Pressure Resistance of Verotoxigenic and Nontoxigenic Escherichia coli

Carriage of stx2a Differentiates Clinical and Bovine-Biased Strains of Escherichia coli O157

Clade analysis of enterohemorrhagic Escherichia coli serotype O157:H7/H- strains and hierarchy of their phylogenetic relationships

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