Characterization of Escherichia coli isolated from healthy dogs

Five month old dogs from a Midwestern research kennel occasionally develope d bloody diarrhea after shipment to other facilities. As previous diagnosti c efforts failed to reveal any potential pathogens in feces from normal and diarrheic dogs, Escherichia coli was investigated for select virulence pro perties that may contribute to the occurrence of bloody diarrhea. Fecal swa bs from 52 healthy dogs were examined for E. coli. Two hundred and sixty E, coli-like colonies were screened by PCR for the attaching and effacing (ea e) gene, Shiga toxin (stx) genes, and the heat-stable enterotoxin type A (s ta) gene. One hundred forty two of the 260 E. coli-like colonies (54.6%) fr om 43 dogs were eae or sla positive; and 60 of the eae and/or sta positive isolates were examined further. Among the 60 isolates, 23 (38.3%) possessed the ene gene, 32 (53.3%) possessed the sta gene, and five (8.3%) possessed both eae and sia genes (eae(+)/sta(+)), Of the 60 isolates, six sta(+) and one eae(+)/sta(+) isolates were hemolytic. When examined in the suckling m ouse assay, five of six sta(+) isolates and three of four eae(+)/sta(+) iso lates gave gut-to-remaining carcass ratios greater than or equal to 0.083, indicating expression of heat-stable enterotoxin. These enterotoxin-produci ng isolates belonged to serogroups O42, O170, and O-negative, (C) 1999 Else vier Science B.V. All rights reserved.