title: Variation in stress resistance patterns among stx genotypes and genetic lineages of shiga toxin-producing Escherichia coli O157.
abstract: To evaluate the relationship between bacterial genotypes and stress resistance patterns, we exposed 57 strains of Shiga toxin-producing Escherichia coli (STEC) O157 to acid, freeze-thaw, heat, osmotic, oxidative, and starvation stresses. Inactivation rates were calculated in each assay and subjected to univariate and multivariate analyses, including principal component analysis (PCA) and cluster analysis. The stx genotype was determined for each strain as was the lineage-specific polymorphism assay (LSPA6) genotype. In univariate analyses, strains of the stx(1) stx(2) genotype showed greater resistance to heat than strains of the stx(1) stx(2c) genotype; moreover, strains of the stx(1) stx(2) genotype showed greater resistance to starvation than strains of the stx(2) or stx(2c) genotypes. LSPA6 lineage I (LI) strains showed greater resistance to heat and starvation than LSPA6 lineage II (LII) strains. PCA revealed a general trend that a strain with greater resistance to one type of stress tended to have greater resistance to other types of stresses. In cluster analysis, STEC O157 strains were grouped into stress-resistant, stress-sensitive, and intermediate clusters. In stx genotypes, all strains of the stx(1) stx(2) genotype were grouped with the stress-resistant cluster, whereas 72.7% (8/11) of strains of the stx(1) stx(2c) genotype grouped with the stress-sensitive cluster. In LI strains, 77.8% (14/18) of the strains were grouped with the stress-resistant cluster, whereas 64.7% (11/17) of LII strains were grouped with the stress-sensitive cluster. These results indicate that the genotypes of STEC O157 that are frequently associated with human illness, i.e., LI or the stx(1) stx(2) genotype, have greater multiple stress resistance than do strains of other genotypes.
authors.affiliation: Graduate School of Agricultural and Life Sciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Lee
authors.forename: Nigel P
authors.initials: NP
authors.lastname: French
authors.forename: Geoff
authors.initials: G
authors.lastname: Jones
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hara-Kudo
authors.forename: Sunao
authors.initials: S
authors.lastname: Iyoda
authors.forename: Hideki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sugita-Konishi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsubone
authors.forename: Susumu
authors.initials: S
authors.lastname: Kumagai
mesh_terms: D006801:Humans; D000143:Acids / Q000633:toxicity; D003080:Cold Temperature; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D019453:Escherichia coli O157 / Q000145:classification / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D005838:Genotype; D006358:Hot Temperature; D050296:Microbial Viability; D058889:Molecular Typing; D009997:Osmotic Pressure; D016877:Oxidants / Q000633:toxicity; D018384:Oxidative Stress; D011110:Polymorphism, Genetic; D022621:Shiga Toxin / Q000235:genetics; D013312:Stress, Physiological; D000818:Animals; D002417:Cattle
chemical_list: D000143:Acids; D016877:Oxidants; D022621:Shiga Toxin