PREVALENCE OF F107 FIMBRIAE ON ESCHERICHIA-COLI ISOLATED FROM PIGS WITH EDEMA DISEASE OR POSTWEANING DIARRHEA

The study comprises fifty 4 to 12 weeks old pigs that died from oedema disease or severe diarrhoea. Smears were prepared from the mucosa of duodenum, jejunum and ileum, and by immunofluorescence F107 fimbrial a ntigens were detected. E. coli strains were isolated from the intestin es and were characterised by slide agglutination (serogroup and F107 f imbriae production), by their cytotoxicity for Vero cells, and by gene amplification (genes coding for the major F107 subunit FedA, the toxi n causing oedema disease SLT-IIv, and enterotoxins LTI, STIa and STII) . F107 fimbriae were demonstrated in association with E. coli of serog roups O139:K12 and O141:K85a,b but not of serogroup O149:K91 :F4a,c. E xpression in culture of F107 fimbriae by some isolates gave additional evidence for production of these fimbriae by ETEC strains. The geneti c determinant of SLT-IIv was found in association with F107, and could not be detected in serogroup O149:K91:F4a,c. Gene fedA was demonstrat ed in two isolates which were devoid of SLT-IIv. Most isolates from ca ses of oedema disease belonged to serogroup O139:K12 and did not conta in enterotoxin genes. Isolates from pigs that suffered from diarrhoea were serotyped O141:K85a,b or O149:K91:F4a,c, and carried at least two enterotoxin genes in their genomes. In a small proportion of the case s F107 antigens were demonstrated in intestinal smears although gene f edA was not detected in the corresponding isolates. The results confir m the importance of F107 fimbriae as virulence factor in oedema diseas e E. coli strains, but also demonstrate that F107 fimbriae can be foun d in association with postweaning diarrhoea isolates. In these latter strains enterotoxins were always demonstrated, irrespective of the pre sence of toxin SLT-IIv.