Detection of Verotoxigenic Escherichia Coli O157 and O26 in Food by Plating Methods and LAMP Method

Detection of Verotoxigenic Escherichia coli O157 and O26 in food by plating methods and LAMP method: A collaborative study
29.feb.08
International Journal of Food Microbiology
National Institute of Health Sciences, Tokyo Metropolitan Institute of Public Health, Saitama Institute of Public Health
Yukiko Hara-Kudo, Noriko Konishi, Kayoko Ohtsuka, Reiji Hiramatsu, Hiroyuki Tanaka, Hirotaka Konuma and Kosuke Takatori

In order to establish a rapid and sensitive method for the detection of Verotoxigenic Escherichia coli O157 and O26, a collaborative study was conducted focusing on a comparison of the efficiency of loop-mediated amplification (LAMP) assay targeting the Verocytotoxin (also called Shiga toxin) gene, utilizing a direct plating method and a plating method with immunomagnetic separation (IMS-plating method) using various agar media. In combination with enrichment with the modified EC supplemented with novobiocin, E. coli O157 was detected in most samples of ground beef and alfalfa sprouts by LAMP assay, the direct plating method and the IMS-plating method. E. coli O26 was detected in approximately 100% of the food samples by LAMP assay. However, the IMS-plating and direct plating methods recovered 80 and 50% in ground beef samples, respectively. As a result, it was demonstrated the LAMP assay is superior to the IMS-plating method. Based on these results, it appears LAMP assay is effective as a screening assay to detect E. coli O157 and O26 from positive samples.

Note from SproutNet:  This must be from artificially contaminated sprouts and beef.