Binding of E. coli isolates from pigs with postweaning diarrhea or edema disease to crude intestinal mucin of a weaned pig.

The presence of the fedA (gene coding F18 fimbriae) and genes coding STa and LTI enterotoxins and verotoxin Stx2v was determined in 30 E. coli strains isolated from weaned pigs with postweaning diarrhea (PWD) and edema disease (ED). The fedA gene was detected in 22 strains (73.3%). It was mostly associated with the presence of ST gene determinant (14 from 22 fedA positive strains, 63.6%). Two strains possessed ST/Stx2v or LTI/Stx2v combination of genes for both toxins and two strains were negative for investigated toxin determinants. Among 8 fedA-negative strains, five strains without gene determinants for toxins were detected. All 30 E. coli strains were investigated for their binding to crude intestinal mucin of a weaned pig fixed in wells of microtitre plates. Positive mucin binding was observed in most of strains, however, great differences were shown between individual strains. Nineteen strains were classified as strongly adherent, 10 strains as weakly adherent, and only one nonadherent strain was found. Three E. coli strains, selected among the best mucin binders, bound to mucin in a concentration-dependent manner. A high mucin binding by E. coli strains was observed only after their cultivation on blood agar plates. Their cultivation in LB broth or on McConkey agar plates had negative effect on the mucin binding by these strains. The mucin binding is not restricted by the presence of fedA gene because the strains displaying very good binding are found either among fedA positive (1, 602/2, 4/3, 576/6) or fedA negative (DK 6, DK 8) E. coli strains. E. coli strains with the highest mucin binding ability belong to potential ST producents (strains 1, 602/2, 4/3, 6/2, 602/4) while the strains without genes coding toxin production displayed lower binding to mucin substratum with exception of the strains ZV5 and 13.