Detection and characterisation of O157:H7 and non-O157 Shiga toxin-producing Escherichia coli in wild boars

The aim of this work was to determine the prevalence and characteristics of Escherichia coli O157:H7 and non-O157 Shiga toxin-producing E. coli (STEC) in free-ranging wild boars killed during the hunting season in southwest Spain. Faecal samples from 212 wild boars (Sus scrofa) were collected and examined for STEC. Characterisation of isolates was performed by PCR, serotyping, phage typing, and pulsed-field gel electrophoresis (PFGE). E. coli O157:H7 and non-O157 STEC were isolated from 7 (3.3%) and 11 (5.2%) animals, respectively, and the resulting 19 isolates were characterised. The PCR procedure indicated that 4 isolates carried the stx1 gene, 12 carried the stx2 gene, and 1 contained both of these genes. The ehxA, eae, and saa genes were detected in 13, 8, and 1 of the isolates, respectively. The eae-positive isolates comprised the types eae-γ1 and eae-ζ. The isolates belonged to 11 O:H serotypes, including 4 new serotypes not previously reported within STEC strains, and the majority of them were from serotypes previously associated with human infection. E. coli O157:H7 isolates belonged to phage types associated with severe human illness: PT14, PT34, and PT54. Indistinguishable PFGE types were found in E. coli O157:H7 isolates recovered from a wild boar and from a human patient with diarrhoea living in the same geographic area.S. Sánchez acknowledges the Consejería de Educación y Ciencia de la Junta de Comunidades de Castilla-La Mancha and Fondo Social Europeo for his research fellowship (09/02-C). R. Martínez acknowledges the Junta de Extremadura for his research fellowship (PRE06053). A. Mora acknowledges the Ramón y Cajal programme from the Ministerio de Educación y Ciencia. This study was supported by grants from the Junta de Extremadura and FEDER (grant 3PR05A009-III Plan Regional de Investigación), from the Xunta de Galicia (grants PGIDIT065TAL26101PR and 07MRU036261PR), from the Ministerio de Educación y Ciencia (AGL-2008-02129), and from the Fondo de Investigación Sanitaria (Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Spanish Network for the Research in Infectious Diseases, REIPI, RD06/0008-1018).Peer Reviewe