1. Gram positive endospore forming rods
Clostridium botulinum—anaerobic—adult and infant botulism
Clostridium perfringens—anaerobic—diarrhea
Bacillus cereus—facultatively anaerobic—gastroenteritis (diarrhea and vomiting)

2. Why do bacteria form endospores
Survival of the bacterial species
Endospores carry the genomic information of the vegetative cell

3. Vegetative cells vs. endospores
Vegetative cells are metabolically active
(taking in nutrients, converting nutrients into energy and biomass, expelling wastes, growing and dividing)
Endospores are dormant—metabolically inactive (but contains the genetic material of the vegetative cell)

4. Why are endospores dormant?
Filled with SASPS (small acid soluble proteins that protect DNA)
Has low water activity
Has relatively few metabolic enzymes
Surrounded by a tough keratin-like coat

5. How does being dormant benefit an endospore
Can survive the following conditions
drying
high heat
UV irradiation
low pH
high osmolarity
low temperature
Conditions that most vegetative cells cannot survive

6. Life cycle of an endospore
Vegetative cell (unpleasant conditions)
Veg. cell replicates DNA, forms a septum 1/3 of the length of the cell and pumps DNA into the region
Endospore develops at that site and is finally surrounded by a tough keratin like coat
Veg cell dies releasing the mature endospore
Free mature endospore (pleasant conditions)
Endospore germinates to become a vegetative cell

7. Clostridium botulinum
Causes botulism (food posioning)
Causes infant botulism from honey
Abundant in soil throughout the world
Type A C. botulinum—found in neutral/alkaline soil west of the Mississippi River
Type B C. botulinum—found in eastern part of the country
Type C C. botulinum—found in wet soils (can effect fish)

8. Botulism cases are rare
Foodborn botulism—50 cases per annum usually due to home canning of food (Type A and Type B) or preserved fish (Type E)
Infant botulism—100 cases per annum usually due to spores present in honey that is introduced to formula

9. Foodborn botulism—toxin formed in food
Canning—endospores are not eradicated if the temperature is not sufficiently high
Spores are present in a nutrient rich environment that is also anaerobic
The spores germinate and become vegetative bacteria
The vegetative bacteria produce botulism toxin—a potent neurotoxin

10. Botulism toxin Toxin has no taste
Food is often not spoiled by the bacteria
A small amount of food with the toxin can be lethal
Botulism toxin is heat labile

11. Infant botulism—(3-20 weeks old)
Toxin is formed in the infant’s colon
Honey has a high osmolarity; therefore, the endospores cannot germinate
Honey is mixed with infant formula that dilutes the honey—the infant drinks the solution
The spores are introduced into the stomach and move to the colon
The spores germinate in the colon
The vegetative cells produce botulism neurotoxin in the colon

12. Clinical diseases caused by botulism neurotoxin (cause)
Foodborn botulism hours after ingestion toxin travels to different parts of the body
Botulism toxin binds to acetocholine receptors on neural cells
Impulses are not sent from one neural cell to another
Muscles (smooth, involutary, motor) are not stimulated by the neurons and cannot move
This causes flaccid paralysis of the muscles

13. Clinical diseases caused by botulism neurotoxin (effect)
Flaccid paralysis of muscles
Cranial nerves are the first affected
double vision/blurred vision
difficulty swallowing
Muscles in the arms and legs are next to be affected
Diaphragm muscles are affected causing difficulty in breathing
There is no fever or cell death
END RESULT:: paralysis and respiratory failure

14. Treatment Deliver antitoxin to the three known botulism neurotoxin
The antitoxin binds to the free circulating neurotoxin and prevents it from binding to acetocholine receptors
N.B. Bound neurotoxin cannot be inactivated as it is already bound to acetocholine receptors
Supportive therapy—intubation until neurons regenerate

15. Infant botulism-diseases and treatment
Disease is slow in occurring because toxin cannot be readily absorbed from the colon
2-3 days constipation
Difficulty swallowing—poor suckling response
Flaccid baby
Hospitalization and intubation may be required
Prognosis is usually good so no antitoxin is required
N.B. SIDS has been attributed in part to infant botulism

16. Bacillus cereus
B. cereus is facultatively anaerobic and found in every environment.
Causes abdominal pain and diarrhea
AND/OR
Nausea/vomiting

17. Disease caused by B. cereus
Disease is caused by two toxins
Enterotoxin—heat stable/proteolysis resistant
--Causes nausea and vomiting
--Found commonly in improperly stored rice
Heat labile form
--Causes watery diarrhea as water is not absorbed in the intestines
--Found commonly in contaminated meats vegetables and sauces
--Takes longer to get sick as disease is caused as B. cereus divides in the patients G-I tract