Analysis of the Clonal Relationship of Serotype O26:H11 Enterohemorrhagic Escherichia coli Isolates from Cattle

Abstract

Twelve cluster groups of Escherichia coli O26 isolates found in three cattle farms were monitored in space and time. Cluster analysis suggests that only some O26:H11 strains had the potential for long-term persistence in hosts and farms. As judged by their virulence markers, bovine enterohemorrhagic O26:H11 isolates may represent a considerable risk for human infection.

Rapid Microarray-Based Genotyping of Enterohemorrhagic Escherichia coli Serotype O156:H25/H−/Hnt Isolates from Cattle and Clonal Relationship Analysis

“…In contrast to the O26:H11 isolates that we had analyzed in the same monitoring program (28), the identified EHEC O156:H25 isolates did not represent independent cluster groups on each farm. Despite the relatively large geographic distance between the farms, we found members of the same cluster groups in different farms.…”

“…The nucleotide sequences of intimin genes of three isolates (WH-02/23/021-2, WH-02/25/010-9, and WH-04/25/005-1) were determined by PCR (Primer-fwd, 5Ј-GTTTCCCGCTCGATGATGCTAC-3Ј; Primerrev, 5Ј-GCGAATAGAAAAGGTGGCTGGAG-3Ј) followed by DNA sequencing in a LiCOR 4200 system using the DYEnamic direct cycle sequencing kit (GE Healthcare Europe GmbH, Freiburg, Germany). A plasmid profile analysis was also conducted (28,29).…”

“…Preparation of genomic DNA for contourclamped homogeneous electric field-pulsed-field gel electrophoresis (CHEF-PFGE) was done by a protocol described previously (28,29,38). Slices of the DNA agarose plugs were equilibrated in the respective restriction endonuclease buffer and then digested for 4 h with XbaI, NotI, BlnI (AvrII), or SpeI (New England Biolabs GmbH, Frankfurt am Main, Germany).…”

Detection of the Emerging Shiga Toxin-Producing Escherichia coli O26:H11/H − Sequence Type 29 (ST29) Clone in Human Patients and Healthy Cattle in Switzerland

“…The majority (11/16) of the human ST21 strains harbored only stx 1a , four strains possessed (Table 2), ST21 strains (eae ϩ ) showed plasmid gene profiles described for human STEC O26 strains of ST21 (1), whereas Shiga toxin genes were lacking. However, ST21 is also frequently found in STEC O26 strains from cattle (7,9). Such E. coli O26 strains can probably undergo transition via loss and gain of Stx-encoding phages, as has been shown for human E. coli O26 (6,16).…”

“…However, the environmental reservoirs and sources of STEC O26: H11/H Ϫ strains belonging to the emerging ST29 clone are widely unknown. Cattle and sheep, major reservoirs of STEC, are also reservoirs for STEC O26 (7,8,9,10), but STEC O26 strains harboring stx 2a only and belonging to ST29 have to our knowledge not yet been described. In this study, we determined the phylogeny and clonal structure, stx genotypes (Shiga toxins), and plasmid gene profiles of STEC O26:H11/H Ϫ strains from human patients and of E. coli O26:H11/H Ϫ from healthy cattle and sheep in Switzerland.…”