Direct detection of Bacillus cereus enterotoxin genes in food by multiplex Polymerase Chain Reaction
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Date
2008-05
Authors
Gicheru, M. M.
Ombui, J.N.
Gitahi, N.
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of Integrative Biology
Abstract
This study evaluated a direct multiplex PCR to detect food contamination with enterotoxigenic
Bacillus cereus
(B. cereus)
in comparison with culture and multiplex ge
ne detection using colonies. Detection of
B. cereus
enterotoxin genes was done on artificially contaminated
and ready-to- eat market foods including cooked rice,
pasteurized milk and cheese. Of the 108 food samples
analysed, 51(47.2 % were found to be contaminated with
enterotoxigenic
B. cereus
by culture and enterotoxin detection by
multiplex PCR, but only 14(12.9%) of them
were found to be contaminat
ed with enterotoxigenic
B. cereus
by direct multiplex PCR.
B. cereus
enterotoxin
genes were detected only in artificially contaminated an
d ready-to-eat market foods with bacterial counts of
equal or more than 4000 (4x10
3
)cfu/ml for both pasteurized milk and
cheese and equal or more than 40,000
(4x10
4
) cfu/g for cooked rice. Since high contamination of food with
B. cereus
(10
6
cfu/g) has been associated
with food poisoning, this technique can be used to id
entify foods suspected to cause food poisoning without
culture and identification of
B. cereus.
Detection of any of the enterotoxin genes will indicate contamination of
foods with enterotoxigenic
B. cereus
group
Description
Keywords
Citation
International Journal of Integrative Biology (IJIB), 2008, Vol. 2, No. 3, 172