Bacillus Cereus

Question 1

What kind of organism

Answer 1

Gram positive bacilli,

Question 2

Found in?

Answer 2

soil, plants, vegetables, stool in some asymptomatic people

Question 3

Virulence factors?

Answer 3

Protease
Collagenase
Toxins- Cereulide and Diarrhoeal toxins

Question 4

Cerulide toxin

Answer 4

Responsible for emetic disease. Causes stimulation of the vagus nerve

Question 5

Diarrhoeal

Answer 5

Haemolysin (HBL)- causes the watery stool to occur (1 binding and 2 lytic parts- CDA.)
Non-Haemolytic Enterotoxin- cause pore formation (Three parts ABC NHE)
Beta barel pore forming toxins- 2 parts CytK and Hlyll

Question 6

Types of infection

Answer 6

Emetic - vomitting within 1-6 hrs.
Diarrhoeal- due to eating food with or without the toxin. toxin made inside small intestine.
Non GIT infection- BSI, Meningitis, gas gangrene etc

Question 7

Isolate on

Answer 7

Blood agar, PEMBA

Question 8

PEMBA

Answer 8

Polymixin - selective
Egg Yolk and mannitol- differential for lethcinase and mannitol fermentaton
Bromothymol blue- causes colour change to peacock blue

Question 9

Confirmatory tests

Answer 9

VP, Urease, Fermentation of carbohydrates

Detection of toxins

Question 10

Carbohydrates test

Answer 10

To test production of acid when trehalous or glucose is present. Colour change occurs to pink to yellow when it occurs.

Question 11

Urease

Answer 11

Tests ability of the organsim to use urease to break down urea into ammonia and CO2. Colour change from yellow to pink.

Question 12

VP

Answer 12

Tests ability to breakdown glucose to a neutral product after forming an acidic product. Yellow to pink for positive result. Add kovac’s reagent

Question 13

Toxin detection

Answer 13

Emetic- Toxin antibodies

Diarrhoael- HBL and NHE antibodies