title: Phylogenetic analysis and Shiga toxin production profiling of Shiga toxin-producing/enterohemorrhagic Escherichia coli clinical isolates.
abstract: Shiga toxin-producing Escherichia coli (STEC) can cause severe illnesses in humans such as hemorrhagic colitis and hemolytic-uremic syndrome. In this study, we carried out genotypic analysis of the Shiga toxin (stx) gene in 120 clinical isolates of STEC and enterohemorrhagic E. coli (EHEC) from patients in a southern district of Japan. We identified 88 stx(1)(+) and 103 stx(2)(+) strains. We further identified 12 stx(1)(+) and stx(2)(+) isolates expressing little or no Shiga toxin 1 (Stx(1)) and/or 2 (Stx(2)) by reversed passive latex agglutination (RPLA) and Vero cell toxicity assays. Among them, 1 strain could not produce Stx(1), 8 could not produce Stx(2), and 3 strains could produce neither. Two of the latter three strains were of the non-O157 serotype. Most of the Stx RPLA-negative strains belonged to the stx(1)/stx(2) subtype (11/12, [91.7%]). Our quantitative reverse transcription PCR analysis indicated that the stx genes were not effectively transcribed in the RPLA-negative strains. This is the first report of the isolation of stx-positive strains showing Stx-negative phenotype from stx(1)-bearing strains and non-O157 strains.
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka, Japan.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.forename: Takaaki
authors.initials: T
authors.lastname: Harada
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Honjoh
authors.forename: Takahisa
authors.initials: T
authors.lastname: Miyamoto
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D054324:Enterohemorrhagic Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D020869:Gene Expression Profiling; D005838:Genotype; D006801:Humans; D007564:Japan; D007841:Latex Fixation Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D022621:Shiga Toxin / Q000096:biosynthesis* / Q000235:genetics*; D014709:Vero Cells; D014774:Virulence
chemical_list: D004269:DNA, Bacterial; D022621:Shiga Toxin