FSC-342 Quiz #3: Lecture 10 - Clostridium Perfringens

What is Clostridium perfringens?

A Gram-positive, non-motile, spore-forming rod that is anaerobic but more O₂-tolerant than C. botulinum.

What type of illness does C. perfringens cause?

A toxico-infection, where toxin is produced inside the host during sporulation in the small intestine.

Where is C. perfringens commonly found?

Soil, dust, intestinal tracts of humans and animals, feces, and about 50% of raw/frozen meats.

What are the most common food vehicles for C. perfringens?

High-protein foods (meats, poultry, pork), especially beef.

What is the temperature growth range of C. perfringens?

15°C – 50°C, with optimum 43–45°C.

What is the generation time of C. perfringens at optimum temperature?

7–10 minutes.

At what temperature does C. perfringens show no growth?

6°C.

What is the minimum water activity (aw) for C. perfringens growth?

0.93–0.97 (not tolerant of low aw).

What is the pH growth range of C. perfringens?

5.0–8.3, optimum 6.0–7.0.

What is the infective dose of C. perfringens?

Greater than 10⁶ vegetative cells/g of food.

What is the onset time of illness from C. perfringens?

8–16 hours after consumption.

What are the main symptoms of C. perfringens food poisoning?

Severe abdominal pain and diarrhea; nausea, fever, and vomiting are rare.

How long does C. perfringens illness typically last?

12–24 hours, usually self-limiting.

Who is most at risk from C. perfringens food poisoning?

The elderly and debilitated.

What is CPE (Clostridium perfringens enterotoxin)?

A single polypeptide toxin (319 amino acids, 35 kDa) encoded by the cpe gene.

How sensitive is CPE to heat?

Heat labile; inactivated at 60°C for 5 minutes, also sensitive to pH extremes.

Where does CPE act in the body?

Small intestine and ileum; damages villus tips within 15–30 minutes.

When is CPE produced and released?

Only during sporulation; released when mother cell lyses.

How common are CPE-positive strains?

Less than 5% of isolates; Type A strains (chromosomal gene) cause human food poisoning.

What is the “classic outbreak scenario” for C. perfringens?

Large meat pieces (e.g., turkey) inadequately cooked, cooled too slowly, and improperly reheated.

What are the top contributing factors in C. perfringens outbreaks?

Improper storage/holding (97%), improper cooking (65%), contaminated equipment (28%), poor hygiene (26%).

How can C. perfringens outbreaks be prevented?

Thorough cooking, rapid cooling, avoiding the Danger Zone, storing refrigerated, slicing large meat portions.

What are USDA cooling guidelines for meats?

130–80°F in <1.5 hours; 80–40°F in <5 hours.

How is C. perfringens food poisoning identified?

Detecting >10⁶ cells/g in food, spores in feces, matching serotypes in food/victim, or detecting CPE via ELISA/DNA probes.