Bacillus

Question 1

Characteristics of bacillus

Answer 1

Gram +
Spore forming
Aerobe or facultative anaerobe
Mesophilic, psychrophilic and thermophilic

Question 2

Species of bacillus

Answer 2

Cereus, subtilis, licheniformis, pumilus

Question 3

Sources of cereus

Answer 3

Soil (veg and cereals)
Meat, egg and dairy

Question 4

What is classified as an outbreak of cereus?

Answer 4

10^10cfu/g

Question 5

What can cereus toxins cause?

Answer 5

Emetic and diarrhoeal syndrome at >10^5cfu/g

Question 6

Characteristics of emetic syndrome

Answer 6

1-5h onset
Lasts 6-24h
Nausea, vomiting
Rare death due to liver failure

Question 7

Structure of cereus toxins

Answer 7

Pre-formed toxin cyclic peptide (short onset)
3 repeats of 4 peptide unit dodeca-depsi-peptide
200-270kb plasmid
Cluster of plasmid-carried genes

Question 8

How does the cereus toxin act?

Answer 8

Via the vagus nerve

Question 9

Characteristics of cereus toxin

Answer 9

Optimal early production at 25-30C
Heat and pH stable (126C for 90mins and pH 2-11)
Protease resistant

Question 10

Sources of emetic syndrome

Answer 10

Starchy foods, milk, eggs

Question 11

Characteristics of diarrhoeal syndrome

Answer 11

Incubation 8-16h
Duration 24-48h
Diarrhoea and abdominal pain

Question 12

What are the 3 toxins of bacillus?

Answer 12

Hemolysin BL (Hbl)
Non haemolytic enterotoxin (Nhe)
Cytotoxin K

Question 13

What are the sources of bacillus toxins?

Answer 13

Cooked meat and poultry
Dessert and sauces
Vegetables
Soups, stews and spices

Question 14

What is bacillus thuringiensis (BT)?

Answer 14

Production of crystalline delta toxin
Produced as parasporal body during sporulation

Question 15

What is bacillus anthracis?

Answer 15

Species that causes anthrax through toxins

Question 16

What are the 2 plasmids that determine the virulence of bacillus anthracis?

Answer 16

pxO1 and pxO2

Question 17

How does bacillus anthracis effect animals?

Answer 17

Ingestion of spores from soil
Swelling in throat and neck, shock, death

Question 18

How does bacillus anthracis get to humans?

Answer 18

Dust (95% mortality)
Contact with wool (swelling, 20% mortality)
Foods (95% motality)

Question 19

Characteristics of subtilis

Answer 19

10min-14h onset
2-8h lived
Vomiting and diarrhoea
Meat with pastry or rice, bakery items

Question 20

What is amylosin and subtilisin?

Answer 20

Cytotoxins, subtilisin causes allergic reaction

Question 21

Characteristics of licheniformis

Answer 21

2-14h onset
6-24h lived
Vomiting, diarrhoea and cramps
Any meat product
Insensitive to heat, protease, acid or alkali

Question 22

What is lichenysin?

Answer 22

Toxin that destroys membranes

Question 23

Characteristics of pumilis

Answer 23

15mins-11h onset
Several days lived
Vomiting, dizziness followed by cramps and diarrhoea
Meat, pastry, rice, cheese sandwiches

Question 24

What is the cfu/ml required to cause illness in subtilis, licheniformis and pumilis?