The AIDA autotransporter system is associated with F18 and Stx2e in Escherichia coli isolates from pigs diagnosed with edema disease and postweaning diarrhea
U. Niewerth et al., The AIDA autotransporter system is associated with F18 and Stx2e in Escherichia coli isolates from pigs diagnosed with edema disease and postweaning diarrhea, CL DIAG LAB, 8(1), 2001, pp. 143-149
Pathogenic Escherichia call strains are known to cause edema disease (ED) a
nd postweaning diarrhea (PWD) in piglets. Although the exact mechanisms of
pathogenicity that lead to ED-PWD remain to be elucidated, E,coli-borne Shi
ga-like toxin and adhesion-mediating virulence factors such as F18 adhesin
or F4 fimbriae are believed to play a central role in ED-PWD, In light of t
hese observations we investigated whether another E, call adhesin, the plas
mid-encoded AII)A (adhesin involved in diffuse adherence) might also be pre
sent in ED-PWD-causing E, coli isolates, For rapid screening for the AIDA s
ystem in large numbers of isolates, a multiplex PCR method along with a dup
lex Western blot procedure was developed. When screening 104 strains obtain
ed from pigs with or without ED-PWD, we observed a high prevalence of the A
IDA operon in porcine E, coli isolates, with over 25% of all strains being
AIDA positive, and we could demonstrate a significant association of the in
tact AIDA gene (orfB) with ED-PWD, while defects in orfB were associated wi
th the absence of disease. Although our data hint toward a contribution of
AIDA to ED-PWD, further studies will be necessary since the presence of the
AIDA genes was also associated with the presence of the Shiga-like toxin a
nd F18 adhesin genes, two reported virulence factors for ED-PWD.