[Hazard evaluation of livestock-derived, verotoxin-producing Escherichia coli by enterohemolysin production assay and eaeA gene detection].
We examined enterohemolysin (Ehly) production, and detected the hlyA gene and the eaeA gene for the intestinal mucosal adherence factor intimin in 131 strains of human-derived verotoxin-producing Escherichia coli (VTEC) and 140 strains of livestock (cattle and swine) -derived VTEC to evaluate their hazards to humans. The hlyA gene was confirmed in 98.5% of human-derived, in 50.5% of cattle-derived, and in 10.3% of swine-derived VTEC strains. Ehly-positive rates were 96.2-97.7%, 45.9-55.0%, and 10.3-20.7% in human-, cattle-, and swine-derived VTEC strains, respectively. Thus, the positive rates differed among strains of different species origins. However, all 12 cattle-derived O157VTEC strains had hlyA, and were Ehly-positive. Although 97.7% of human-derived strains and all cattle-derived O157VTEC strains had eaeA, only 8.1% of cattle derived strains of serotypes other than O157 and 3.4% of swine-derived strains had eaeA. In human- and cattle-derived strains, the presence of eaeA was associated with Ehly: all eaeA-carrying strains had hlyA, and almost all of them were Ehly-positive. Cattle-derived eaeA-carrying strains accounted for 29.5-35.3% of Ehly-positive strains, compared to 100% in human-derived strains. Only 3-4% of Ehly-negative strains had eaeA, and none of the non-hlyA-carrying strains had eaeA. These findings suggest that 2 factors, eaeA and Ehly, serve as useful indicators for the evaluation of hazard to humans, and that Ehly is a useful indicator because cattle-derived Ehly-positive strains may have eaeA.
Kobayash
Takahiro
T
Oita Prefectural Meat Inspection Center.
Narimatsu
Hiroshi
H
Fuchi
Yuichi
Y
D018829:Adhesins, Bacterial / Q000235:genetics*; D000818:Animals; D002417:Cattle / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification*; D029968:Escherichia coli Proteins / Q000235:genetics*; D006460:Hemolysin Proteins / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D022603:Shiga Toxins / Q000096:biosynthesis*; D013552:Swine / Q000382:microbiology*
D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D022603:Shiga Toxins; C066219:enterohemolysin; C073819:eaeA protein, E coli