FSC-342 Quiz #2: Lecture 9 - Clostridium Botulinum

What food conditions first created an environment for C. botulinum spores to grow?

Sausages that were boiled then stored at room temperature in an anaerobic environment.

What was discovered about the cause of botulism illness?

It was caused by preformed toxin, not infection.

How does the botulinum toxin affect the body?

It binds to motor nerves, blocks acetylcholine release, and causes flaccid paralysis leading to possible respiratory failure.

What is the main cause of 40% of U.S. botulism cases?

Improper home canning of vegetables.

What mistakes in home canning caused botulism outbreaks in 2008/2009?

Failure to use a pressure canner in low-acid, anaerobic foods (green beans, carrots, pears, asparagus).

What starchy ingredient has caused botulism outbreaks in Utah (2011) and Arizona (2012)?

Baked potatoes stored anaerobically in sealed containers at room temperature.

What are the three main types of human botulism?

Foodborne, wound, and infant botulism.

Which toxin types cause human botulism?

Types A, B, E, and rarely F.

What is infant botulism?

Ingestion of spores that germinate, grow, and produce toxin in the infant’s intestine (ages 1–12 months), often linked to honey, dust, or corn syrup.

What are the symptoms of infant botulism?

Constipation, muscle weakness, difficulty swallowing, loss of head control, floppiness ("floppy baby syndrome"), respiratory issues.

What are the general characteristics of C. botulinum?

Gram-positive, anaerobic, spore-forming rods.

What are the two major groups of C. botulinum?

Group I (Proteolytic) and Group II (Nonproteolytic).

What are the growth temperatures of Group I and Group II C. botulinum?

Group I minimum 10°C (optimum 37°C), Group II minimum 3°C (optimum 30°C).

Which group of C. botulinum is targeted in low-acid canned food processing?

Group I (Proteolytic), with D121°C of 0.2 min and 12-D process.

Which group of C. botulinum is less heat resistant?

Group II (Nonproteolytic), with D100°C < 0.1 min.

What are the minimum pH values for C. botulinum growth?

Group I: 4.6, Group II: 5.0.

What are the salt and water activity limits for C. botulinum growth?

Group I: 10% NaCl (aw 0.94), Group II: 5% NaCl (aw 0.97).

Why can C. botulinum still grow in oxygen-exposed foods?

Heating drives out dissolved oxygen; slow diffusion back keeps food anaerobic for hours.

What background microflora can inhibit C. botulinum?

Psychrotrophs (by spoilage) and lactic acid bacteria (by lowering pH).

What preservatives inhibit C. botulinum?

Nitrite, sorbates, polyphosphates, nisin, spices (pepper, bay leaf, nutmeg, garlic), and gamma irradiation.

Where is C. botulinum commonly found in the environment?

Soils and sediments (type B strains proteolytic in U.S., nonproteolytic in Europe).

What foods commonly contain C. botulinum spores?

Fish, meats, fruits, and vegetables in contact with soil.

Who is susceptible to foodborne botulism?

Anyone.

Who is susceptible to infant botulism?

Infants 1–12 months old, and adults on antibiotics/chemotherapy.

How potent is the botulinum toxin?

Lethal dose is 0.1–1.0 × 10⁻⁶ g (100,000 times stronger than rattlesnake venom).

How can botulinum toxin be inactivated?

Boiling or heating at 80°C for 10 minutes.

What is the onset time for botulism?

3 hours to 14 days (average 12–36 hours) after ingestion of toxin.

What are the first symptoms of foodborne botulism?

Nausea and vomiting (especially types B and E).

What are the neurological symptoms of botulism?

Blurred or double vision, difficulty swallowing, dry mouth, muscle weakness, progressing to paralysis and possible respiratory failure.

What treatments are used for botulism?

Antitoxin, induced vomiting, mechanical respirators.

What is the current fatality rate of botulism with treatment?

Reduced from 50% to less than 10%.

What is the mode of action of the botulinum toxin?

Blocks acetylcholine release from nerve terminals, causing paralysis.

What medical use does the botulinum toxin have?

Botox, which uses small, safe amounts for cosmetic and therapeutic purposes.

Check of Knowledge: What control is required for canned green beans (pH 5.8, aw 0.98)?

Retort at 121°C for 2–3 minutes (12D121°C).