Food Poisoning Caused By

8/3/2019 Food Poisoning Caused By

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FOOD POISONING CAUSED BY

GRAM

POSITIVESPORE FORMING BACTERIA


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Bacillus cereus


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Introduction ofBacillus cereus

Considered a minor foodborne panthogen, but one thatis increasingly important.

Bacillus cereus disease is not notifiable.

B. cereus causes


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Characteristics of the Organisms

o Bacteria : aerobic rod shaped bacterium .

Bacillus

cereus

group

B.anthracis

B. thuringiensis

B. pseudomycoides

B. weihenstephanensis

B. mycoidesB. cereus


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o B. anthracis the most distinctive member of this group.

highly virulent pathogenicity.

notoriety as an agent for biological warfare.

o B. thuringiensis

natural bioinsecticide caused cases ofB. cereusfood poisoning.


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Environmental Sources

Present in soil at10^5 /g

Spread to cowsudders and into raw

milk

Survive milkpasteurization

Causing problems inmany milk

productions

osoil and growing plants.oB. cereus always problematic in dairy foods.


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Characteristics of Disease

Emetic toxin

Result : vomiting

Enterotoxin(s)

Result : diarrhea

2 typeB. cereus

foodborne illness


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o The incubation time ( >6 hours ; average ; 12 hours ) is too long for

diarrheal illness.o Enterotoxin(s) form in food B. cereus population is at least 100-

fold higher than that necessary.


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Dose

- Grew it to 4 x 10^6cells / ml

- Drank 200 ml of the

culture

13 hours later,abdominal pain and

watery diarrhea

B. cereus rangingfrom 200 to 10^9

organisms /g (or ml)

Total doseapproximately 5 x 10^4

cells/ml to 1 x 10^11cells/ml.

Enough toxin toproduce illness is

probably 10^5 and10^8 cells.

Food containing >10B.cereus organisms/g not

safe to eat.

Foodborne illness in Oslo, Norway ( from vanilla sauce )


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The Emetic Toxin

o the recent discovery that Hep-2 cells could detect the toxin has ledto its purification and structure determination.

o The emetic toxin is now named cereulide.

o Cereulide has 3 repeats of four amino acid and/or oxyacids

[ D-O-Leu-D-Ala-L-O-Val-L-Val ]3o Resistant to autoclaving, a wide range of pH values (2 to 11) and

digestion by proteases.


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Enterotoxins


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o Microslide diffusion tests are used to detectB. cereus diarrheagenicand staphylococcal enterotoxins.

o Antiserum to the toxin is put into well 1 and reference toxin is putinto well 3.

o Test sample are put into wells 2,4, and 5.

o When the antiserum and toxin diffuse from their respective wellsand meet, a precipatation line is formed.

o (A) Test where the food samples are negative but a line is formedwith the known enterotoxin.

o (B) Test where the sample in well 4 contains enterotoxin.

o (C) Photo of actual results, where samples in wells 2 and 4

(but no 5) are positive for toxin.


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Controlso Handling the food in the right way.

o Store the milk production between the temperature 4 to 8C.

o

Avoid cross

contamination.

Food Poisoning Caused By

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