Prevalence and deletion types of the pathogenicity island ETT2 among Escherichia coli strains from oedema disease and colibacillosis in pigs

Piglet pathogenic Escherichia coli encoding Shigatoxin 2e and F18 adhesins are the etiological agents of oedema disease as well as of non-oedema disease colibacillosis. In order to reveal virulence differences among this pathogen, the presence of the pathogenicity island (PAI) E. coli type three secretion system 2 (ETT2) was examined. Using PCR and Southern blot techniques for the identification of the right, the middle, and the left region of this 29.9kb large genetic element, the entire ETT2 was found among E. coli O138:H(-), O139:H1, and O147:H6 strains originated from cases of oedema disease in Germany between 1995 and 2001 and belonging to various clonal types. In contrast, non-oedema disease E. coli isolates (e.g. O8:H19, 101:H(-), O141:H4) contain deleted subtypes of ETT2. These deletions cover the translocon part of the putative ETT2-encoded type III secretion apparatus. It is suggested that the entire ETT2 is associated with a particular virulence trait of piglet oedema disease E. coli (EDEC).