Properties of Vero cytotoxin-producingEscherichia coliof human and animal origin belonging to serotypes other than O157: H7

Abstract

SUMMARYEight non-O157: H7 Vero cytotoxin (VT)-produeingEscherichia coli(VTEC) strains isolated from ill persons and nine bovine and lamb strains of serogroups matching the human strains, were characterized for various properties known to be associated withE. colivirulence. Five different serogroups were represented: O5. O55, O103, O111 and O153. The bovine and lamb strains produced VT1, while 3 human strains produced VT1, 3 produced VT2 and 2 were positive for both VT1 and VT2. The strains were non-haemolytic on horse blood agar, did not produce either heat stable toxin A (STA) or heat labile toxin (LT), and were non-invasive. The CVD419 probe which has been proposed to identify enterohaemorrhagicE. coli(EHEC) hybridized with all of the 05 and 0103 strains, none of the 055 and 0153 strains, and 3 of the 4 0111 strains. The strains carried several different sized plasmids and hybridization of Southern blots with the CVD419 probe identified plasmids ranging in size from 42 × 10 to 90 × 10. The strains did not hybridize with the enteroadherence factor (EAF) probe derived from an enteropathogenic strain and associated with the ability to give localized adherence to HEp-2 cells. Nevertheless five of the strains adhered in a localized pattern to HEp-2 cells and Intestine 407 cells. Adhesion to either HEp-2 or Intestine 407 cells did not correlate with hybridization with the CVD419 probe or haemagglutinating properties.