Attaching and effacing lesions in vivo and adhesion to tissue culture cells of Vero-cytotoxin-producing Escherichia coli belonging to serogroups 05 and O103

Abstract

Summary: Certain isolates of Escherichia coli from humans and animals with enteric disease attach to enterocytes and cause ‘attaching and effacing’ (AE) lesions. E. coli strain S22-1, serotype O103:H2, isolated from a child with diarrhoea, contained two plasmids; one of these (pDEP12) hybridized with the CVD419 DNA probe derived from a plasmid found in E. coli 0157:H7 and associated with expression of fimbriae and ability to adhere to Intestine 407 cells. Strain S102-9, serotype O5:H-, isolated from a calf with dysentery, contained six plasmids, one of which also hybridized with the CVD419 probe. Loss of pDEP12 coincided with reduced adhesion to HEp-2 or Intestine 407 cells cultured in vitro; reintroduction of this plasmid restored adhesiveness. Loss of the plasmid in strain S102-9 that hybridized with the CVD419 probe did not cause a decrease in adhesion. Accumulations of actin were seen in vitro in the fluorescence actin staining (FAS) test of strains S22-1, S102-9 and their derivatives, irrespective of the plasmid content of these strains or the prevalence of attached bacteria. Strain S22-1 and its plasmidless derivative caused AE lesions of equal severity in experimentally infected gnotobiotic piglets; piglets inoculated with an isolate from a healthy human or pig did not develop these lesions. These results indicate that the CVD419 probe is not specific for genes conferring the ability to adhere to HEp-2 or Intestine 407 cells by these E. coli and that the adhesins detected in vitro, or plasmid-encoded properties, are not required for strain S22-1 to cause AE lesions in gnotobiotic pigs or to cause the accumulation of actin in cells in vitro.