Occurrence of fimbriae and enterotoxins in Escherichia coli strains isolated from piglets in Poland.

1125 and 1146 E. coli strains isolated from suckling and weaned piglets with diarrhea, respectively, and 724 strains from healthy piglets were tested for the presence of fimbriae and production of enterotoxins. The fimbriae were determined by hemagglutination and slide agglutination tests, enterotoxins--by the use of ileal loop test in piglets (LT and STb enterotoxins) and suckling mouse assay (STa enterotoxin). It was found that 72.8 and 53.0% strains, isolated from diseased suckling and weaned piglets, respectively, possessed specific fimbrial hemagglutinins, in most cases with K88 antigen. Additionally, 987P fimbriae were detected in 14.0 and 0.7% strains isolated from piglets with diarrhea. Only 5 strains (0.7%) recovered from healthy piglets had specific fimbriae, usually with undetermined antigenic structure. F1 fimbriae (called common or unspecific) were found in strains isolated both from diseased (15.2 and 16.3% strains, respectively) and healthy piglets (27.1% strains). It was noted that the strains isolated from suckling and weaned piglets with diarrhea in most cases were enterotoxigenic (90.5 and 69.1% strains, respectively) and most frequently produced heat-labile toxin LT alone or with STb. 18.5% of enterotoxigenic strains isolated from healthy piglets produced STa toxin.