AIMS: To establish whether investigated subtyping methods could identify any specific characteristics that distinguish Swedish VTEC O157:H7 strains isolated from cattle farms associated with human enterohaemorrhagic Escherichia coli (EHEC) cases from cattle strains isolated in prevalence studies. METHODS AND RESULTS: Strains (n = 32) isolated in a dairy herd prevalence study and strains isolated from farms associated with human cases (n = 13) were subjected to typing. Partial sequencing of the vtx(2) genes could not identify any unique variants of vtx(2) or vtx(2c) in strains associated with human cases. A specific variant of VTEC O157:H7, which was overrepresented among farms associated with human cases (P = 0·01), was by two different single-nucleotide-polymorphism (SNP) assays identified as clade 8, a subgroup of VTEC O157:H7 strains considered to be putatively hypervirulent. Multi-locus variable number tandem repeat analysis (MLVA) typing of all strains produced similar results as pulsed-field gel electrophoresis (PFGE) typing regarding clustering of the strains, but MLVA distinguished slightly better among strains than PFGE. CONCLUSION: In Sweden, VTEC O157:H7 strains from the putatively hypervirulent clade 8 are overrepresented among isolates from cattle farms associated with human cases compared with VTEC O157:H7 strains isolated in prevalence studies. SIGNIFICANCE AND IMPACT OF THE STUDY: Real-time PCR SNP typing for clade 8 can be used to identify cattle farms that are at higher risk of causing EHEC infections in humans.
AIMS: To establish whether investigated subtyping methods could identify any specific characteristics that distinguish Swedish VTEC O157:H7 strains isolated from cattle farms associated with human enterohaemorrhagic Escherichia coli (EHEC) cases from cattle strains isolated in prevalence studies. METHODS AND RESULTS: Strains (n = 32) isolated in a dairy herd prevalence study and strains isolated from farms associated with human cases (n = 13) were subjected to typing. Partial sequencing of the vtx(2) genes could not identify any unique variants of vtx(2) or vtx(2c) in strains associated with human cases. A specific variant of VTEC O157:H7, which was overrepresented among farms associated with human cases (P = 0·01), was by two different single-nucleotide-polymorphism (SNP) assays identified as clade 8, a subgroup of VTEC O157:H7 strains considered to be putatively hypervirulent. Multi-locus variable number tandem repeat analysis (MLVA) typing of all strains produced similar results as pulsed-field gel electrophoresis (PFGE) typing regarding clustering of the strains, but MLVA distinguished slightly better among strains than PFGE. CONCLUSION: In Sweden, VTEC O157:H7 strains from the putatively hypervirulent clade 8 are overrepresented among isolates from cattle farms associated with human cases compared with VTEC O157:H7 strains isolated in prevalence studies. SIGNIFICANCE AND IMPACT OF THE STUDY: Real-time PCR SNP typing for clade 8 can be used to identify cattle farms that are at higher risk of causing EHEC infections in humans.
Authors: R Söderlund; C Jernberg; S Ivarsson; I Hedenström; E Eriksson; E Bongcam-Rudloff; A Aspán Journal: J Clin Microbiol Date: 2014-08-20 Impact factor: 5.948
Authors: Eelco Franz; Angela H A M van Hoek; Fimme J van der Wal; Albert de Boer; Ans Zwartkruis-Nahuis; Kim van der Zwaluw; Henk J M Aarts; Annet E Heuvelink Journal: J Clin Microbiol Date: 2011-12-21 Impact factor: 5.948
Authors: Glen E Mellor; Eby M Sim; Robert S Barlow; Beatriz A D'Astek; Lucia Galli; Isabel Chinen; Marta Rivas; Kari S Gobius Journal: Appl Environ Microbiol Date: 2012-04-27 Impact factor: 4.792
Authors: M F Anjum; E Jones; V Morrison; R Tozzoli; S Morabito; I Toth; B Nagy; G Smith; A Aspan; E M Nielsen; P Fach; S Herrera-León; M J Woodward; R M LA Ragione Journal: Epidemiol Infect Date: 2013-07-18 Impact factor: 4.434
Authors: K Verstraete; K DE Reu; S VAN Weyenberg; D Piérard; L DE Zutter; L Herman; J Robyn; M Heyndrickx Journal: Epidemiol Infect Date: 2013-02-28 Impact factor: 4.434