[Development of a rapid separating incubation method for detection of Escherichia coli O157:H7 in food]

Abstract

To detect Escherichia coli O157:H7 in food, a selective and differential medium, CTV-MUG-RSMAC agar, was designed. Using this medium, the growth of most interfering organisms could be inhibited, and three main biochemical characteristics, including sorbitol-negative, rahmnose-negative and MUG-negative, to identify E. coli O157:H7 could also be simultaneously recognized. Sorbitol-positive aberrance strains of E. coli O157:H7 could be distinguished on the medium. The procedure of detecting food sample includes adding sample to selective broth and incubating overnight at 42 degrees C, streaking the inoculum to CTV-MUG-RSMAC agar and incubating at 37 degrees C for 24 h, and picking the typical colonies to react with sera for O157 and H7 antigens, and then take biochemical tests. The procedure could be finished within 3 days. This method has been applied to 126 food samples, and E. coli O157:H7 was detected from 3 samples. The results were in coincidence with those using FDA method.