Long-term excretion of Shiga toxin-producing Escherichia coli (STEC) and experimental infection of a sheep with O157.
To investigate a long-term shedding of Shiga toxin (Stx)-producing Escherichia coli (STEC) from sheep, a fifteen-month study for STEC isolation from a sheep, which had yielded STEC before, was attempted. The sheep continued to shed STEC and 39 STEC were isolated. The number of STEC in the feces was estimated at 1.7 x 10(3) per gram. In addition, although Stx1-negative O157 and stx2-encoding bacteriophage were experimentally infected to the sheep, Stx-positive O157 or Stx2- producing bacterial cells were not detected. The genetical and biochemical characterization of those 39 STEC strains showed that all STEC strains produced Shiga toxin 1 (Stx1) and were divided into three classes (I to III). From phylogenetic analysis of their amino acid sequences, class-I STEC was classified as group 1 comprising mainly human STEC, and classes II/III were as group 2 comprising sheep STEC. Our results suggest that STEC easily colonized in sheep and that the sheep continued to shed STEC, showing that sheep might be an important reservoir for human STEC infection.
Kim
Suk
S
Department of Veterinary Microbiology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
Asakura
Hiroshi
H
Kuri
Asumi
A
Watarai
Masahisa
M
Shirahata
Toshikazu
T
Takeshi
Kouichi
K
Tsukamoto
Teizo
T
Makino
Sou-ichi
S
D000818:Animals; D004197:Disease Reservoirs; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*; D005243:Feces / Q000382:microbiology*; D010802:Phylogeny; D012703:Serotyping; D034561:Sheep, Domestic / Q000382:microbiology*; D022603:Shiga Toxins / Q000302:isolation & purification*; D013997:Time Factors; D015047:Zoonoses / Q000382:microbiology
D022603:Shiga Toxins