title: Prevalence and growth kinetics of Shiga toxin-producing Escherichia coli (STEC) in bovine offal products in Japan.
abstract: Recent epidemiological data suggest a link between the consumption of bovine offal products and Shiga toxin-producing Escherichia coli (STEC) infection in Japan. This study thus examined the prevalence of STEC in various types of these foods. PCR screened 229 bovine offal products for the presence of Shiga toxin (stx) gene. Thirty-eight (16·6%) samples were stx positive, of which eight were positive for rfbE(O157) and three were positive for wzy(O26). Four O157 and one O26 STEC isolates were finally obtained from small-intestine and omasum products. Notably, homogenates of bovine intestinal products significantly reduced the extent of growth of O157 in the enrichment process compared to homogenates of beef carcass. As co-incubation of O157 with background microbiota complex from bovine intestinal products in buffered peptone water, in the absence of meat samples, tended to reduce the extent of growth of O157, we reasoned that certain microbiota present in offal products played a role. In support of this, inoculation of generic E. coli from bovine intestinal products into the homogenates significantly reduced the extent of growth of O157 in the homogenates of bovine intestinal and loin-beef products, and this effect was markedly increased when these homogenates were heat-treated prior to inoculation. Together, this report provides first evidence of the prevalence of STEC in a variety of bovine offal products in Japan. The prevalence data herein may be useful for risk assessment of those products as a potential source of human STEC infection beyond the epidemiological background. The growth characteristic of STEC O157 in offal products also indicates the importance of being aware when to test these food products.
authors: Division of Biomedical Food Research, National Institute of Health Sciences, Tokyo, Japan. hasakura@nihs.go.jp
authors: H
authors: H
authors: Asakura
authors: E
authors: E
authors: Saito
authors: Y
authors: Y
authors: Momose
authors: T
authors: T
authors: Ekawa
authors: M
authors: M
authors: Sawada
authors: A
authors: A
authors: Yamamoto
authors: A
authors: A
authors: Hasegawa
authors: J
authors: J
authors: Iwahori
authors: T
authors: T
authors: Tsutsui
authors: K
authors: K
authors: Osaka
authors: T
authors: T
authors: Matsushita
authors: M
authors: M
authors: Kakinuma
authors: K
authors: K
authors: Motoyama
authors: Y
authors: Y
authors: Hayama
authors: H
authors: H
authors: Kitamoto
authors: S
authors: S
authors: Igimi
authors: F
authors: F
authors: Kasuga
mesh_terms: D000818:Animals; D002417:Cattle / Q000382:microbiology*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000209:etiology; D019453:Escherichia coli O157 / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D007422:Intestines / Q000382:microbiology; D007564:Japan / Q000453:epidemiology; D008461:Meat Products / Q000382:microbiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015995:Prevalence; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification