Pathogenic Escherichia coli strains are known to cause edema disease (ED) and postweaning diarrhea (PWD) in piglets. Although the exact mechanisms of pathogenicity that lead to ED-PWD remain to be elucidated, we investigated whether another E. coli adhesin, the plasmid-encoded adhesin involved in diffuse adherence (AIDA) might also be present in ED-PWD-causing E. coli isolates. It was showed that E. coli strains attach to HEp-2 cell assay in three different patterns. Twenty-two isolates were from faeces of preweaned pigs and 36 isolates were from faeces of postweaned pigs. The base sequences for specific oligonucleotide primers of PCR used in this study were constructed based on the regions of conserved sequences between forward (5′-3′) ACAGTATCATATGGAGCCA and reverse (5′-3′) TGTGCGCCAGAACTATTA. Product size was 585 base pairs. A total of 58 AIDA-positive E. coli were used for cell adherence pattern analysis of HEp-2 cell assay. Forty three isolates showed three distinct patterns that were localized adherence (LA), diffuse adherence (DA) and aggregative adherence (AA) patterns respectively. But fifteen isolates were nonadherent. LA (14 isolates) pattern was the most common, followed by DA (13 isolates) and AA (9 isolates) pattern. And three isolates showed a combination of the LA and AA patterns and 4 isolates showed a combination of the DA and AA patterns. Escherichia coli strains that cause nonbloody diarrhea in infants are known to present three distinct patterns of adherence to epithelial cells, namely, localized (LA), diffuse (DA), and aggregative (AA) adherence.

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REFERENCES

• Heejin Ham(Department of Animal Health and Welfare, Hoseo University, 20 Hoseo-ro 79 beon-gil, Baebang-eup, Asan-si, Chungcheongnam-do 31499, Korea) Corresponding author