Foodborne Intoxications and Staphylococcal Poisoning

Foodborne Intoxications

• Foodborne intoxication occurs when consuming food containing a pre-formed toxin produced by a microbe.
• Toxins can be heat-labile or heat-stable.
• Symptoms appear quickly (as early as 30 minutes) after ingestion.
• Symptoms vary depending on the type of toxin, with enterotoxins causing gastric issues and neurotoxins causing neurological problems.
• Fever is not a typical symptom.

Staphylococcal Food Poisoning

• Staphylococcal food poisoning, caused by Staphylococcus aureus toxins, is a frequent worldwide foodborne illness.
• It was a major cause of outbreaks before the 1980s, but outbreaks have decreased due to better refrigeration and hygienic handling practices.
• The number of staphylococcal food poisoning outbreaks and cases surpasses several other microbial foodborne diseases.

Characteristics of Staphylococcus aureus

• Staphylococcus aureus are gram-positive cocci, usually in clusters.
• They are non-motile, non-encapsulated, and non-sporulating.
• Most strains ferment mannitol and produce coagulase and thermonuclease.
• Staphylococcus aureus are facultative anaerobes that grow rapidly under aerobic conditions.
• The cells are destroyed at 66°C for 12 minutes, and 72°C for 15 minutes.

Staphylococcus aureus Continued

• They can ferment carbohydrates and cause proteolysis via extracellular proteolytic enzymes.
• Their optimal growth temperature is 20°C to 37°C, with growth possible between 7°C and 48°C.
• Staphylococcus aureus can grow at low water activity (Aw), low pH, high salt, and sugar concentrations, and in the presence of nitrite.
• Staphylococcus aureus are relatively poor competitors compared to other organisms in food, but their ability to grow in unfavorable conditions gives them an advantage.
• Enterotoxin-producing strains are linked with staphylococcal food poisoning.

Botulism

• Botulism results from consuming food containing a potent toxin called botulin, produced by Clostridium botulinum.
• Botulism produces neurological symptoms and some gastric issues.
• Untreated botulism is often fatal.
• Infant botulism occurs when infants ingest Clostridium botulinum spores.
• These germinate, multiply, and produce toxins within the gastrointestinal tract.

Characteristics of Clostridium botulinum

• Clostridium botulinum are gram-positive, rod-shaped bacteria.
• They can occur as single cells or in chains; many are motile
• They're obligate anaerobes.
• Form single terminal spores.
• Sensitive to low pH (<4.6), low water activity (Aw), and moderate salt concentration (5.5%).
• Spores are highly heat-resistant (killed at 115°C).
• Cells are killed at moderate heat (pasteurization)
• Toxins are formed during growth.

Clostridium botulinum Continued

• Clostridium botulinum strains are divided based on the type of toxin they produce (A, B, C, D, E, F)
• Types A, B, E, and F are associated with human foodborne illnesses.
• Proteolytic strains grow between 10°C and 48°C, with optimal growth at 35°C.
• Non-proteolytic strains grow optimally at 30°C, with a range of 3.3 to 45°C.
• Optimum growth facilitates optimum toxin production
• Anaerobic conditions are necessary for growth.

Spore Distribution of Clostridium botulinum

• Spores are widespread in soil, sewage, mud, lakes, coastal waters, plants, and intestinal contents of animals and fishes.
• Fruits and vegetables can be contaminated from soil, fishes, and other foods.
• Type A and B spores are prevalent in soil, sewage, and animal feces.
• Type E spores are typically found in marine environments.

Botulism Toxins

• Botulinum toxins are neurotoxic proteins.
• Toxins associated with food intoxication (types A, B, E, and F) are potent.
• A small amount can produce severe symptoms and cause death.
• Toxins are absorbed from the intestine, spread to nerves, and block signal transmission.
• This causes muscle paralysis, especially affecting the diaphragm, lungs, and heart.
• Death typically results from respiratory failure.

Botulism Toxins Continued

• Toxins produced by non-proteolytic strains are not fully active and require activation by trypsin in the digestive tract.
• Heat-labile toxins are destroyed by high uniform heat treatments (90°C for 15 mins, or boiling for 5 mins).
• Growth is necessary for toxin production.
• Toxin production is high during optimal growth.

Botulism Disease and symptoms

• Botulism is caused by ingestion of botulinum toxin.
• Initial symptoms (12–36 hours, but could be faster) include gastrointestinal issues (nausea, vomiting, diarrhea, constipation).
• Neurological symptoms (blurred vision, difficulty swallowing/breathing, and speaking, and paralysis) quickly follow.
• Death results from respiratory failure in severe cases.

Food Association (Botulism)

• Botulism outbreaks are linked to improperly canned low-acid foods (fruit/vegetables).
• Cooked/stored foods left at temperatures suitable for bacterial growth can result in outbreaks.
• Low-acid vegetables (such as green beans, corn, and spinach) are frequently implicated.
• Finfish (fermented, undercooked, and smoked fish), are also frequently involved.
• Baked potatoes, chili peppers, and other condiments can also be involved in outbreaks.

Prevention of Botulism

• Proper temperature and time control during food preparation (home canning, cooking) reduces the likelihood of botulism.
• Refrigeration (3°C or below) reduces the risk of spore germination and toxin production.
• Heat-stable toxins cannot be removed by heating, so the entire food needs to be properly cooled.

Mycotoxicosis

• Mycotoxicosis is caused by eating foods containing mold metabolites (mycotoxins).
• Mycotoxins are not proteins or digestive tract toxins; however, many are carcinogens.
• Many cause organ toxicity via unknown mechanisms; in recent decades, several animals and birds (including turkeys) have seen large incidence of deaths due to toxins.
• Mycotoxins are not easily destroyed by heating.

Mycotoxicosis Characteristics

• Toxigenic mold strains from various genera produce mycotoxins.
• Mycotoxins are not easy to differentiate.
• Molds grow best under warm, humid, aerobic conditions.
• Molds can thrive even with low water activity (Aw), low temperature, and low pH levels.

Mycotoxin Prevention

• Avoid consuming foods with visible mold growth.
• Proper storage conditions and packaging methods inhibit mold growth.
• Heat treatment is ineffective for many mycotoxins.
• Chemicals (e.g., ammonia, hydrogen peroxide, sodium hypochlorite) may help destroy mycotoxins.
• Regulatory agencies set limits for certain mycotoxins (e.g., aflatoxins).

This quiz focuses on foodborne intoxications, particularly those caused by Staphylococcus aureus. You'll learn about the types of toxins, symptoms, and the historical significance of staphylococcal food poisoning outbreaks. Test your knowledge on how these microbes affect health and safety.