Food Poisoning Etiology and Outbreaks

Food Poisoning Etiology

• Food poisoning arises from consuming contaminated food containing pathogenic microorganisms, toxins, or chemicals.
• Causes include infectious bacteria, viruses, biotoxins, and chemical contaminants like insecticides and heavy metals.
• Two-thirds of foodborne outbreaks are due to bacteria.

Foodborne Outbreaks

• Two or more individuals experience similar gastrointestinal illness after consuming a common food.
• Epidemiological analysis pinpoints food as the source within 72 hours of exposure.

Factors in Foodborne Diseases (1)

• Inadequate food manipulation, including improper holding temperatures (lack of refrigeration), insufficient cooking time, and contaminated equipment (lack of cleaning and disinfection protocols).

Factors in Foodborne Diseases (2)

• Poor personal hygiene during food preparation, serving food more than a day prior to consumption without proper holding and reheating, cross-contamination (transfer of harmful microorganisms from raw to cooked food), and the addition of contaminated ingredients to previously cooked food.

Foodborne Disease by Microbial Agents

• Intoxications due to preformed toxins within the food.
• Intoxications due to toxins produced within the body after organism ingestion.
• Intestinal invasive diseases caused by microorganisms invading the intestines.

Food Poisoning Symptoms

• Symptoms vary depending on the contaminant source.
• Common symptoms include nausea, vomiting, watery diarrhea, abdominal pain/cramps, and fever.
• Illness duration ranges from a few hours to several days. Most cases resolve on their own.

Foodborne Disease by Microbial Agent - 1

• Nausea and vomiting within 1-6 hours typically result from preformed enterotoxins produced by S. aureus and B. cereus.
• Abdominal cramps and diarrhea occurring 8-16 hours post-consumption are often linked to Clostridium perfringens.
• Fever, abdominal cramps, and diarrhea within 16-48 hours might stem from tissue invasion by Salmonella, Shigella, Campylobacter jejuni, Vibrio parahaemolyticus, and invasive E. coli.

Foodborne Disease by Microbial Agent - 2

• Abdominal cramps and diarrhea within 16-72 hours may result from enterotoxins produced in in vivo (e.g., ETEC, Campylobacter jejuni, Vibrio parahaemolyticus, V. cholerae non-01, and Yersinia enterocolitica).
• Bloody diarrhea without fever within 72-120 hours can be attributed to Verotoxigenic E. coli (serotype O157:H7) producing shiga-like toxins.
• Nausea, vomiting, diarrhea, and paralysis within 18-36 hours can be caused by Clostridium botulinum.

Causes of Food Poisoning

• Staphylococcus aureus (most common): associated with cooked meats, cream-filled foods, and improperly stored foods.
• Clostridium perfringens: linked to improperly stored cooked meats.
• Bacillus cereus: often implicated in 'fried rice'-type food poisoning.
• Clostridium botulinum: primarily causes neurological symptoms and toxin production.

Intoxications Due to Preformed Toxins

• S. aureus (almost always): 99% of cases result from this bacteria.
• B. cereus: heme-creme - 1 day
• C. botulinum.

Staphylococcus Aureus

• Heat-stable, survives autoclaving.
• Foods linked include ham, cream-filled cakes, and potato salad.
• Symptoms include severe nausea, vomiting, abdominal pain, and watery diarrhea (1-6 hours), with illness duration usually under 24 hours.
• Toxin exposure also affects non-human primates and kittens.
• In vitro testing of enterotoxins is used for diagnosis.

Prevention

• Keep hot foods hot (>60°C) and cold foods cold (≤5°C) to prevent spoilage.
• Separate raw from cooked foods.
• Keep kitchen areas and utensils clean.
• Wash and dry hands thoroughly.
• Cover cuts and sores.

Intoxications by Preformed Toxin (Summary)

• S. aureus
• B. cereus
• C. botulinum

Bacillus Cereus (Emetic Form 1)

• Characterized by nausea, vomiting, and abdominal cramps.
• Similar symptoms and course to S. aureus.
• Incubation period: 1-6 hours.
• Caused by a heat-stable enterotoxin; toxin mechanism unknown.

Bacillus Cereus (Emetic Form 2)

• Often linked to fried rice and warm-held foods.
• Diagnosed by isolating B. cereus from the food.

Bacillus Cereus (Diarrheal Form 1)

• Incubation period: 8 to 16 hours.
• Abdominal cramps and diarrhea.
• Usually watery, and sometimes profuse.
• Benign and self-limiting; antibiotics not required.

Bacillus Cereus (Diarrheal Form 2)

• Heat-labile enterotoxin-mediated.
• Activates intestinal adenylate cyclase causing fluid secretion.
• Often associated with meat or vegetable-containing foods.
• Diagnosed through isolation from stool and food.

Clostridium Botulinum

• Found in soil, water, sewage, or plants.
• Grows under anaerobic (oxygen-free) conditions, producing a potent exotoxin.

Botulinum Toxins

• Highly potent, with one gram capable of killing one million people.
• Eight antigenically distinct toxins (A, B, C, D, E, F, G). Each toxin type can be identified.
• Specific toxin types cause human disease (types A, B, E, rarely F)
• Toxins A and B are the most potent.

Foodborne Botulism (1)

• Spores present in food, germinate in anaerobic conditions, releasing toxin into food.
• Ingested preformed toxin is absorbed in the gut and enters the bloodstream.

Foodborne Botulism (2)

• Toxin attaches to presynaptic terminals of cholinergic nerves.
• Blocks neurotransmitter release.
• Nerve impulses cannot be transmitted.
• Muscles do not stimulate, leading to generalized flaccid paralysis.

Foodborne Botulism (Symptoms)

• Symptoms typically arise within 18-36 hours of ingestion and varies in severity.
• Severity ranges from mild to severe; death possible within 24 hours.
• Mortality rate for type A botulism is 75%, with other types having a 20% mortality rate.

Foodborne Botulism (Symptoms (specific))

• Weakness
• Dizziness
• Dry mouth
• Nausea
• Vomiting
• Double vision
• Blurred vision
• Dilated pupils
• Inability to swallow
• Difficulty speaking
• Respiratory paralysis

Botulism Prevention

• Appropriate heat processing during canning or preserving food.
• Spores are inactivated at 100°C for 2 hours or 120°C for 15 minutes.
• Avoid using honey in infant foods as spores might germinate.
• Avoid consuming high-acidity foods at home.

Intoxications due to Toxins Manufactured in Body

• C. perfringens: associated with meat products.
• V. cholerae: associated with seafood or contaminated water.
• ETEC: associated with food.

Clostridium Perfringens

• Spores survive harsh environments.
• Rapid growth in vivo.
• Produces many toxins; Type A causes food poisoning.

C. perfringens Serotypes

• Classified based on exotoxin types.

C. perfringens Food Poisoning

• Incubation period is 8-12 hours.
• Symptoms include nausea, vomiting, cramps, diarrhea.
• Associated with improperly cooled meat products, causing spore germination and toxin production in the gastrointestinal tract.

C. perfringens Prevention

• Keep hot foods hot (>60°C) and cold foods cold (≤5°C).
• Cool food quickly.
• Divide large food volumes into smaller portions; thoroughly heat food before serving.

Laboratory Procedures

• Stool samples can be examined for WBCs (differentiating invasive from non-invasive pathogens) and ova/parasites via methylene blue staining/wet-mount method.

Food Handler Examination

• Stool, vomitus, blood, and toxin presence in stool, nose, and hands are critical for diagnosis.

Therapy/Treatment

• In most cases, food poisoning is self-limiting. Supportive care, such as fluid replacement, is usually sufficient.
• Antiperistaltic drugs are generally not recommended.

Specific Food and Associated Pathogens (Example Summary)

• Fried Rice: B. cereus (emetic form)
• Beef, poultry: C. perfringens

Susceptible Individuals

• Infants
• Older adults
• Pregnant individuals
• Immunocompromised individuals
• Do not eat raw meats, raw seafood, or raw fish.