Final Exam: Food Safety

Question 1

Type of agent: BACTERIA
General mechanism(s) of action
Examples

Answer 1

General mechanisms of action:
1. PREFORMED TOXIN
Examples: Bacillus cereus, Clostridium botulinum, Staphylococcus aureus

2. INFECTION and PRODUCTION OF ENTEROTOXINS
   Examples: Bacillus cereus, Clostridium botulinum, Clostridium perfringens, Enterotoxigenic E. coli (STEC), Vibrio cholerae
3. INFECTION
   Examples: Campylobacter jejuni, Listeria monocytogenes, Salmonella, Shigella

Question 2

Type of agent: VIRUS
General mechanism(s) of action
Examples

Answer 2

General mechanism of action:
1. INFECTION
Examples: Hepatitis A, Norovirus, Rotavirus, Parvoviruses

Question 3

Type of agent: PARASITE
General mechanism(s) of action
Examples

Answer 3

General mechanism of action:
1. INFECTION
Examples: Cryptosporidiium, Giardia lamblia, Toxoplasma gondii, Trichinella spiralis

Question 4

Type of agent: MARINE ALGAE TOXINS
General mechanism(s) of action
Examples

Answer 4

General mechanism of action:
1. PREFORMED TOXIN
Examples: Brevetoxin (neurotoxic shellfish poisoning), Ciguatoxin (ciguatera), Saxitoxin (paralytic shellfish poisoning)

Question 5

Type of agent: FUNGAL TOXINS
General mechanism(s) of action
Examples

Answer 5

General mechanism of action:
1. PREFORMED TOXIN
Examples: Aflatoxin, Mushroom toxins (amanitin, ibotenic acid, muscarine)

Question 6

Type of agent: FISH TOXINS
General mechanism(s) of action
Examples

Answer 6

General mechanism of action:
1. PREFORMED TOXIN
Examples: Gempylotoxin (escolar), Scombrotoxin (histamine fish poisoning), Tetrodotoxin (puffer fish)

Question 7

Type of agent: CHEMICALS
General mechanism(s) of action
Examples

Answer 7

General mechanism of action: N/A

Examples: Antimony, Arsenic, Cadmium, Copper, Lead, Pesticides (e.g., organophosphates, carbamate), Thallium

Question 8

Describe the components of the FOOD PRODUCTION CHAIN

Answer 8

1. Production
2. Processing
3. Distribution
4. Retail
   4a. Home preparation
   4b. Home consumers
5. Restaurant
   5a. Restaurant preparation
   5b. Restaurant consumers

Question 9

What are (5) current food safety challenges?

Answer 9

1. Changes in our food production and supply
2. Changes in the environment leading to food contamination
3. Rising number of multistage outbreaks
4. New and emerging germs, toxins, and antibiotic resistance
5. New and different contaminated foods (prepackaged raw cookie dough, bagged spinach, and peanut butter)

Question 10

Describe the steps for reporting cases.
1-3 days (2 steps)
1-5 days
0-7 days
2-10 days
Total time: 2-4 weeks

Answer 10

Time from when a person is exposed to Salmonella from contaminated food, water, or infected animal or person to confirmation that he/she is part of an outbreak is 2-4 WEEKS

1-3 days:

1. Person exposed to Salmonella (Time to illness)
2. Stool sample requested (Time to diagnosis)

1-5 days: Person becomes ill (Time to Health Care)

0-7 days: Salmonella identified (Shipping time)

2-10 days: Public health lab receives Salmonella strain (Serotyping and DNA fingerprinting time)

Question 11

What does the FDA Food Safety Modernization Act (FSMA) accomplish?

Answer 11

1. Focus on prevention
   - Mandatory prevention controls for food facilities (hazard analysis of critical control points, HACCP)
   - Mandatory produce safety standards (e.g., use of potable water and compost)
   - Authority to prevent intentional contamination
2. Inspection and compliance
   - Increase frequency of inspection
   - Increase food testing
3. Response: Mandatory recall
4. Imports: Imports must meet US standards

Question 12

SURVEILLANCE
How are reports sent to the Department of Health?

How are all Salmonellas, Shigellas, Listerias, E. coli O157, V. cholerae subtyped?

Answer 12

Clinical laboratories report electronically to the Department of Health

Pulsed field gel electrophoresis (PFGE)

• DNA fingerprint of the bacterial (standardized protocol)
• Standardization of conducting food borne investigations

Question 13

What are some responsibilities of consumers that can decrease one’s risk of contracting food borne illness?

Answer 13

1. CLEAN: wash hands, vegetables and fruits, work area
2. SEPARATE: keep raw meats, poultry, pork from fresh vegetables and fruits
3. COOK: cook to proper temperature
4. CHILL: cook foods properly, chill to 70 degrees Fahrenheit within 2 hours and from 70-45 degrees within 4 hours

Question 14

What are some foods associated with Salmonella outbreaks?

Answer 14

Poultry (22%)
Complex foods (19%)
Produce (17%)
Eggs (11%)
Dairy, Pork, Beef (6%)

Question 15

SALMONELLOSIS
Salmonella species, over (a) serotypes

Name several characteristics of this bacteria

Answer 15

a. 2000 serotypes (S. Enteritidis, S. Typhimurium)

Gram negative facultative anaerobe, non-spore forming, motile bacilli
Fermenter, oxidase-negative

Question 16

Describe the process of salmonella infection

Answer 16

15 min: Invasion of epithelial cells

1 hour: Neutrophil extravasation and increase in vascular permeability (edema)

3 hours: Neutrophil induced tissue injury (epithelial detachment) and beginning of fluid accumulation

8 hours: Effusion of large amount of neutrophils and protein-rich fluid into intestinal lumen

12-48 hours: Pseudomembrane formation and diarrhea (flow of liquid from blood to intestinal lumen)

Question 17

SHIGA TOXIN producing E.COLI (STEC)
(a)-producing E. coli or (b)

Common or rare?

Name several modes of exposure

Answer 17

a. Verocytotoxin-producing E. coli (VTEC)
b. Enterohemorrhagic E. coli (EHEC)

Most COMMON E. coli O157:H7

Exposures:
Consumption of contaminated food
Raw milk, water that hasn’t been disinfected
Contact with feces of infected people

Question 18

What are some other characteristics of E. coli O157:H7
Incubation period?
Clinical symptoms?
Duration of illness?

Answer 18

Incubation period: 2-10 days

Clinical symptoms: severe abdominal cramps, diarrhea, bloody diarrhea, vomiting, kidney failure

Duration of illness: 1-8 days

Gram negative rod, shigatoxin positive