title: Use of low-dose irradiation to evaluate the radiation sensitivity of Escherichia coli O157:H7, non-O157 verotoxigenic Escherichia coli, and Salmonella in phosphate-buffered saline.
abstract: Verotoxigenic Escherichia coli (VTEC) and Salmonella are major foodborne pathogens, but very little information is available on the radiation resistance of a sufficiently diverse group of these pathogens. The objective of this study was to evaluate the sensitivity of E. coli O157:H7, non-O157 VTEC, and Salmonella to a low-dose ionizing radiation treatment. Test organisms were 6 serovars of Salmonella, 5 strains of E. coli O157:H7, and 27 strains of non-O157 VTEC (representing 19 serotypes). Decimal reduction doses (D-values) for individual strains were determined in phosphate-buffered saline using an X-ray source. The viability of the bacterial cells declined with an increase in absorbed dose from 0 to 0.3 kGy. The more resistant test strains were screened at 0.5 and 0.7 kGy. All six Salmonella strains survived at 0.5 and 0.7 kGy; however, only 11 VTEC survived at 0.7 kGy. After the 0.3-kGy treatment, both E. coli O157:H7 and non-O157 VTEC had D-values with similar means and ranges (0.028 to 0.123 and 0.037 to 0.127 kGy, respectively), with no significant differences (P > 0.05). Salmonella strains had a slightly higher range of D-values (0.061 to 0.147 kGy) and a mean D-value that was significantly higher (P > 0.05) than that of both the E. coli O157:H7 and non-O157 VTEC groups.
authors.affiliation: Department of Food Science, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, Manitoba, Canada R2J 3L8.
authors.forename: Devapriya
authors.initials: D
authors.lastname: Kundu
authors.forename: Alexander
authors.initials: A
authors.lastname: Gill
authors.forename: Richard
authors.initials: R
authors.lastname: Holley
mesh_terms: D004307:Dose-Response Relationship, Radiation; D019453:Escherichia coli O157 / Q000528:radiation effects*; D005514:Food Irradiation; D059022:Food Safety; D006801:Humans; D011836:Radiation Tolerance; D012475:Salmonella / Q000528:radiation effects*; D054323:Shiga-Toxigenic Escherichia coli / Q000528:radiation effects*; D014965:X-Rays