Direct detection of Bacillus cereus enterotoxin genes in food by multiplex Polymerase Chain Reaction

Abstract

This study evaluated a direct multiplex PCR to detect food contamination with enterotoxigenic
\nBacillus cereus
\n(B. cereus)
\nin comparison with culture and multiplex ge
\nne detection using colonies. Detection of
\nB. cereus
\nenterotoxin genes was done on artificially contaminated
\nand ready-to- eat market foods including cooked rice,
\npasteurized milk and cheese. Of the 108 food samples
\nanalysed, 51(47.2 % were found to be contaminated with
\nenterotoxigenic
\nB. cereus
\nby culture and enterotoxin detection by
\nmultiplex PCR, but only 14(12.9%) of them
\nwere found to be contaminat
\ned with enterotoxigenic
\nB. cereus
\nby direct multiplex PCR.
\nB. cereus
\nenterotoxin
\ngenes were detected only in artificially contaminated an
\nd ready-to-eat market foods with bacterial counts of
\nequal or more than 4000 (4x10
\n3
\n)cfu/ml for both pasteurized milk and
\ncheese and equal or more than 40,000
\n(4x10
\n4
\n) cfu/g for cooked rice. Since high contamination of food with
\nB. cereus
\n(10
\n6
\ncfu/g) has been associated
\nwith food poisoning, this technique can be used to id
\nentify foods suspected to cause food poisoning without
\nculture and identification of
\nB. cereus.
\nDetection of any of the enterotoxin genes will indicate contamination of
\nfoods with enterotoxigenic
\nB. cereus
\ngroup