title: Survival of O157:H7 and non-O157 serogroups of Escherichia coli in bovine rumen fluid and bile salts.
abstract: While Shiga toxin-producing Escherichia coli (STEC) reside asymptomatically within ruminants, particularly cattle, these strains pose a serious health risk to humans. Research related to STEC has historically focused upon O157:H7. However, with an increase in foodborne outbreaks of non-O157 origin and recent changes in testing for non-O157 by the U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS), there is now a critical need to understand the biological activity of non-O157 serogroups. The focus of this study was to determine whether variations exist in the ability of different serotypes of STEC to survive within bovine rumen fluid medium and bile salts. The results of this study demonstrated through viable plate count analysis that the five serotypes tested (O157:H7, O111:H8, O103:K.:H8, O145:H28, and O26:H11) were capable of growing in rumen fluid medium. However, the concentrations of the serotypes O103:K.:H8 and O26:H11 after 24 h were significantly less (p < 0.05) than that observed for the other serotypes tested. A significant decrease (p = 0.03) in the survival of O103:K.:H8 in 50 mg/mL of bovine bile salts in comparison to the other STEC strains tested was also observed. Collectively, these data suggest that non-O157 serogroups of E. coli respond differently to the environment of the bovine gastrointestinal tract. Further research is needed to elucidate how these differential physiological variations correlate with alterations in colonization success within ruminants and how they may impact human illnesses.
authors.affiliation: Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Free
authors.forename: Heather A
authors.initials: HA
authors.lastname: Duoss
authors.forename: Leeanne V
authors.initials: LV
authors.lastname: Bergeron
authors.forename: Sara A
authors.initials: SA
authors.lastname: Shields-Menard
authors.forename: Emily
authors.initials: E
authors.lastname: Ward
authors.forename: Todd R
authors.initials: TR
authors.lastname: Callaway
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Carroll
authors.forename: Ty B
authors.initials: TB
authors.lastname: Schmidt
authors.forename: Janet R
authors.initials: JR
authors.lastname: Donaldson
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology*; D001826:Body Fluids / Q000382:microbiology; D002417:Cattle; D015169:Colony Count, Microbial; D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000235:genetics; D006801:Humans; D050296:Microbial Viability; D011634:Public Health; D012417:Rumen / Q000382:microbiology*; D022603:Shiga Toxins / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D013045:Species Specificity; D015047:Zoonoses
chemical_list: D001647:Bile Acids and Salts; D029968:Escherichia coli Proteins; D022603:Shiga Toxins