Prevalence and some properties of verotoxin (Shiga-like toxin)-producing Escherichia coli in seven different species of healthy domestic animals

Fecal samples from 720 healthy, domestic animals representing seven different species (cattle, sheep, goats, pigs, chickens, dogs, and cats) were investigated for verotoxin (VT [Shiga-like toxin])-producing Escherichia coli (VTEC). VTEC were isolated from 208 animals (28.9%), most frequently from sheep (66.6% VTEC carriers), goats (56.1%), and cattle (21.1%). VTEC were isolated less frequently from pigs (7.5%), cats (13.8%), and dogs (4.8%) and were not found in chickens (< 0.7%). Forty-one different O:H serotypes and 23 untypeable O-groups were isolated. Five serotypes (O5:H-, O91:H-, O146:H21, O87:H16, and O82:H8) occurred in more than one animal species. Serotypes O5:H-, O91:H-, O146:H21, O128:H2, and OX3:H8 represented 54.8% of the VTEC strains. Nearly 60% of all VTEC O:H serotypes isolated in this study have been implicated as human pathogens, indicating that healthy, domestic animals may serve as a reservoir of human pathogens. All VTEC, except nine feline strains, hybridized with one or both of the VT1 and VT2 specific DNA probes. VT production and enterohemolysin (E-Hly+) production were associated in E. coli from goats, sheep, and cattle but not in E. coli from chickens, pigs, dogs, and cats. A close association of VT with E-Hly+ was found in O5:H-, O146:H21, O128:H2, O77:H4, O119:H25, and O123:(H10) strains. Thirty of 240 (12.5%) E-Hly+ strains hybridized with an E-Hly+ specific DNA probe, indicating heterogeneity of regulatory or structural E-Hly+ genes in strains of E. coli.