title: Characterization of farm, food, and clinical Shiga toxin-producing Escherichia coli (STEC) O113.
abstract: Thirty-nine Shiga toxin-producing Escherichia coli (STEC) O113 Irish farm, abattoir, and clinical isolates were analyzed in conjunction with eight Australian, New Zealand, and Norwegian strains for H (flagellar) antigens, virulence gene profile (eaeA, hlyA, tir, espA, espB katP, espP, etpD, saa, sab, toxB, iha, lpfA(O157/OI-141,) lpfA(O113,) and lpfA(O157/OI-154)), Shiga toxin gene variants (stx(1c), stx(1d), stx(2), stx(2c), stx(2dact), stx(2e), stx(2f,) and stx(2g)) and were genotyped using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). All of the Irish strains were O113:H4, regardless of source, while all non-Irish isolates carried the H21 flagellar antigen. The stx(1) gene was present in 30 O113:H4 strains only, whereas the stx(2d) gene was common to all isolates regardless of source. In contrast, eaeA was absent, while hlyA was found in the Australian, New Zealand, Norwegian, and two of the Irish human clinical isolates. saa was present in the O113:H21 but not in the O113:H4 serotype. To the best of the author's knowledge, this is the first report of clinically significant STEC lacking both the eaeA and saa genes. PFGE analysis was inconclusive; however, MLST grouped the strains into three sequence types (ST): ST10, ST56, and ST223. Based on our findings, it was concluded that the stx(2d) gene is common in STEC O113, which are generally eaeA negative. Furthermore, STEC O113:H4 is a new, emerging bovine serotype of human clinical significance.
authors.affiliation: Department of Food Safety, Teagasc Food Research Centre, Ashtown, Dublin, Ireland.
authors.forename: Aine M
authors.initials: AM
authors.lastname: Monaghan
authors.forename: Brian
authors.initials: B
authors.lastname: Byrne
authors.forename: David
authors.initials: D
authors.lastname: McDowell
authors.forename: Anne M
authors.initials: AM
authors.lastname: Carroll
authors.forename: Eleanor B
authors.initials: EB
authors.lastname: McNamara
authors.forename: Declan J
authors.initials: DJ
authors.lastname: Bolton
mesh_terms: D000003:Abattoirs; D000818:Animals; D001315:Australia / Q000453:epidemiology; D002417:Cattle; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D058885:Multilocus Sequence Typing; D009520:New Zealand / Q000453:epidemiology; D009664:Norway / Q000453:epidemiology; D012703:Serotyping; D022621:Shiga Toxin / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D012988:Soil Microbiology; D037521:Virulence Factors / Q000235:genetics
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D022621:Shiga Toxin