Exam 4- Lecture 15 P3

Question 1

What is food poisoning?

Answer 1

the ingestion of food containing microbial toxins
- microbes do not grow in the host
- will just run its course

Question 2

What is food infection?

Answer 2

the ingestion of food containing viable pathogens
- microbes grow in host & cause damage/diasease
- possibly need more active treatment

Question 3

What are the common causes of food poisoning?

Answer 3

• staphylococcus
• clostridium

Question 4

What are the common causes of food infection?

Answer 4

• salmonella
• campylobacter
• listeria

Question 5

What are two characteristics of staphylococcus aureus that allow the bacteria to grow on food products?

Answer 5

gram-positive and facultative aerobe

Question 6

What does staphylococcus produce?

Answer 6

enterotoxins
- variable among S. aureus strains
- heat stable (prevents degradation)

Question 7

What are the sources of exposure to staphylococcus aureus?

Answer 7

• meat, poultry, and cream-filled desserts
• onset 1-6 hours, duration 48 hours

Question 8

What are two characteristics of clostridium spp. that allow the bacteria to grow on food products?

Answer 8

• spores survive canning/cooking
• germinate in storage

Question 9

What does clostridium spp. produce?

Answer 9

toxins:
- C. perfringens– enterotoxin
- C. botulinum– botulin toxin
* all from canned food

Question 10

What are the sources of exposure to clostridium spp.?

Answer 10

-C. perfringens (most common)- onset 7-15 hours, duration 24 hours
- C. botulinum (dangerous)- canned goods

Question 11

What are the treatment and prevention strategies for food poisoning?

Answer 11

• supportive treatment in extreme cases (fluids & electrolyte replacement)
• sanitation of food production, preparation, and storage

Question 12

What are two characteristics of salmonella that allow the bacteria to infect food?

Answer 12

gram-negative and facultative aerobe
- 2nd most common bacterial food infection

Question 13

What pathogenesis does salmonella have?

Answer 13

• diverse virulence factors
• severe cases- typhoid fever

Question 14

What are the sources of exposure to salmonella?

Answer 14

chronic carriers- typhoid Mary

Question 15

What are two characteristics of campylobacter spp. that allow the bacteria to infect food?

Answer 15

gram-negative and microaerophile
- most common bacterial food infection

Question 16

What pathogenesis does campylobacter spp. have?

Answer 16

inflammation of intestinal epitherlium

Question 17

What are the sources of exposure to campylobacter?

Answer 17

• resident in poultry intestines (90%)
• antibiotics in severe cases

Question 18

What are two characteristics of listeria monocytogenes that allow the bacteria to infect food?

Answer 18

gram-positive and facultative aerobe
- acid, salt, and cold tolerant

Question 19

What is the most severe bacterial food infection?

Answer 19

listeria monocytogenes
- 20% of foodborne illness deaths in the US

Question 20

What pathogenesis does listeria monocytogenes have?

Answer 20

• infection cycle
• severe cases: septicemia and meningitis

Question 21

What are the sources of exposure to listeria monocytogenes?

Answer 21

unpasteurized dairy and prepackaged foods

Question 22

What are the 5 steps of the infection cycle of listeria monocytogenes?

Answer 22

1. Phagocytosis by macrophage
2. Lysis of phagosome, replication
3. Actin-based motility
4. Invasion of adjacent cell
5. Repeat