CPFS Foodborne Illness & Pathogens 2 — Questions and Answers
Question 1: Which food product is most commonly associated with Salmonella Enteritidis contamination?
- Raw oysters
- Unpasteurized juice
- Shell eggs and egg-containing dishes (Correct answer)
- Deli meats
Correct answer: Shell eggs and egg-containing dishes
Salmonella Enteritidis can colonize the interior of intact shell eggs, making shell eggs and dishes made with raw or undercooked eggs a primary vehicle for this pathogen.
Question 2: Listeria monocytogenes is especially hazardous in a foodservice setting because it can grow under which unusual condition?
- At temperatures as low as 32°F (0°C), including refrigeration temperatures (Correct answer)
- Only in high-acid environments below pH 4.6
- Exclusively in dry, low-moisture foods
- Only in the presence of oxygen above 21%
Correct answer: At temperatures as low as 32°F (0°C), including refrigeration temperatures
Unlike most pathogens, Listeria monocytogenes can grow at refrigeration temperatures (34°F–40°F), making it a particular concern for ready-to-eat foods stored in the cooler.
Question 3: Norovirus outbreaks in foodservice establishments are most frequently linked to which vehicle of transmission?
- Undercooked ground beef
- Raw shellfish, especially oysters, or infected food handlers (Correct answer)
- Improperly canned low-acid vegetables
- Cross-contamination from raw poultry
Correct answer: Raw shellfish, especially oysters, or infected food handlers
Norovirus is most often transmitted via raw shellfish (particularly filter-feeding bivalves like oysters) harvested from contaminated waters or directly from infected food handlers through the fecal-oral route.
Question 4: What is the minimum infectious dose for Norovirus, making it highly contagious in foodservice environments?
- Fewer than 20 viral particles (Correct answer)
- At least 10,000 cells
- Over 1 million colony-forming units
- Exactly 500 spores
Correct answer: Fewer than 20 viral particles
Norovirus has an extremely low infectious dose—as few as 18–20 viral particles can cause illness—which is why it spreads so easily in foodservice and healthcare settings.
Question 5: Vibrio parahaemolyticus foodborne illness is most commonly associated with which type of food?
- Reheated rice dishes
- Raw or undercooked shellfish, especially oysters (Correct answer)
- Improperly processed canned goods
- Soft cheeses made from raw milk
Correct answer: Raw or undercooked shellfish, especially oysters
Vibrio parahaemolyticus is a naturally occurring marine bacterium and is most frequently linked to raw or undercooked shellfish, particularly oysters harvested from warm coastal waters.
Question 6: Which practice most effectively prevents the transmission of Hepatitis A virus by food handlers?
- Wearing gloves at all times without washing hands
- Proper and frequent handwashing with soap and water for at least 20 seconds (Correct answer)
- Using hand sanitizer gel before handling food
- Storing food at temperatures below 40°F
Correct answer: Proper and frequent handwashing with soap and water for at least 20 seconds
Handwashing with soap and water for at least 20 seconds is the most effective practice for removing Hepatitis A virus, as alcohol-based hand sanitizers are not reliably effective against non-enveloped viruses.
Question 7: Which symptom pattern is most characteristic of Bacillus cereus emetic (vomiting) syndrome?
- Watery diarrhea appearing 6–15 hours after eating contaminated beef
- Sudden vomiting within 30 minutes to 6 hours after eating starchy foods like fried rice (Correct answer)
- Bloody diarrhea 3–4 days after consuming raw sprouts
- Neurological symptoms 12–36 hours after eating home-canned vegetables
Correct answer: Sudden vomiting within 30 minutes to 6 hours after eating starchy foods like fried rice
The emetic form of Bacillus cereus illness is caused by a heat-stable toxin formed in starchy foods (especially fried rice) and produces rapid-onset vomiting typically within 30 minutes to 6 hours.
CPFS Foodborne Illness & Pathogens 2
Which food product is most commonly associated with Salmonella Enteritidis contamination?