title: 60Co irradiation of Shiga toxin (Stx)-producing Escherichia coli induces Stx phage.
abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC), an important cause of hemolytic uremic syndrome, was completely killed by (60)Co irradiation at 1 x l0(3) gray (1 kGy) or higher. However, a low dose of irradiation (0.1-0.3 kGy) markedly induced Stx phage from STEC. Stx production was observed in parallel to the phage induction. Inactivation of Stx phage required a higher irradiation dose than that for bacterial killing. Regarding Stx, cytotoxicity was susceptible to irradiation, but cytokine induction activity was more resistant than Stx phage. The findings suggest that (1). although (60)Co irradiation is an effective means to kill the bacteria, it does induce Stx phage at a lower irradiation dose, with a risk of Stx phage transfer and emergence of new Stx-producing strains, and (2). irradiation differentially inactivates some activities of Stx.
authors.affiliation: Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, 757 Ichibanchou, Asahimachidori, Niigata, Japan. tatsuoy@med.niigata-u.ac.jp
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Seiichi
authors.initials: S
authors.lastname: Kojio
authors.forename: Ikue
authors.initials: I
authors.lastname: Taneike
authors.forename: Saori
authors.initials: S
authors.lastname: Nakagawa
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Iwakura
authors.forename: Noriko
authors.initials: N
authors.lastname: Wakisaka-Saito
mesh_terms: D000818:Animals; D001435:Bacteriophages / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D002417:Cattle; D003037:Cobalt Radioisotopes; D004269:DNA, Bacterial / Q000528:radiation effects; D004926:Escherichia coli / Q000378:metabolism / Q000528:radiation effects* / Q000821:virology*; D005506:Food Contamination / Q000517:prevention & control*; D006801:Humans; D010957:Plasmids / Q000528:radiation effects; D022621:Shiga Toxin / Q000096:biosynthesis*
chemical_list: D003037:Cobalt Radioisotopes; D004269:DNA, Bacterial; D022621:Shiga Toxin