Transcript Food Borne Illness

Food Borne
Illness
Food Borne Illness
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Food Borne Illness Can be caused by:
• Food Borne Infections ( Living organisms )
• Food Borne Toxins ( non living chemicals )
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Food Poisoning
• Food Borne Toxins ( non living chemicals )
• Generated by Microbes
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Bacteria
Fungi
Algea
• Man made toxins
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Agricultural residues
Antibiotics
Preservatives
• Naturally occuring toxins
Bacterial Food Poisoning
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Toxins that are destroyed by
heating
Clostridium botulinum
Heat stable toxins
Produced by bacteria
Staphylococcus aureus
Clostridium perfringens
Bacillus cereus
Food Borne Infections
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Causes by Bacteria that must grow in
food before eaten
• Require large infective dosage
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Only Bacteria
Caused by Organism that do not
have to grow in the food before it is
eaten
• Require small infective dosage
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Bacteria
Viruses
Parasites
Staphylococcus aureus
Staphylococcal Infections
• Gram-positive cocci in irregular clusters
• Coagulase negative strains make up to 90% of
skin microbiota (S. epidermidis). Only pathogenic
when skin is broken or through invasive entry.
• Coagulase positive strains tend to be pathogenic.
Almost all pathogenic S. aureus strains make
coagulase. High correlation between ability to
produce coagulase and production of damaging
toxins:
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Leukocidin: Destroys phagocytic white blood cells.
Exfoliative toxin: Responsible for scalded skin
syndrome.
Enterotoxins: Affect gastrointestinal tract.
• S. aureus is commonly found in nasal passages.
Staphylococcal Food Poisoning
Characteristics:
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Acute onset of cramps, vomiting, nausea,
occasional diarrhea, low body temperature
and blood pressure.
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Recovery is usually complete within 24
hours.
 Mortality is low in healthy individuals,
higher among immunosuppressed
individuals.
 Pathogens: S. aureus strain that produces
an enterotoxin.
 Reservoir: Human skin, nasal secretions,
and cow milk.
•On Manitol salt agar
Heamolysis on HBA
Staph Poisoning in USA 2000
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Principal symptoms
• Nausea, vomiting, retching, abdominal
cramps, prostration
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Potential food contamination
• Meat and meat products, poultry, egg
• salads (chicken, potato, macaroni),
• cream-filled bakery products, milk and
dairy products
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No. of illnesses
• 185,060
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No. of deaths
• 2
Micro & Macroscopic C. perfringens
NOTE: Large rectangular
NOTE: Double zone of hemolysis
gram-positive bacilli
Inner beta-hemolysis = θ toxin
Outer alpha-hemolysis = α toxin
Clostridial Cellulitis
Exotoxins Associated with
C. perfringens Types A-E
Major
Perfringens Poisoning in USA
2000
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Principal symptoms
Intense abdominal cramps,
diarrhea
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Potential food contamination
 Meat, meat products, gravies
No. of illnesses
 248,520
No. of deaths
 7
Clostridium perfringens
Two syndromes – diarrhoea
and ‘pig-bel’ (necrotizing
enteritis)
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The organism – large, non-
motile G+ve, anaerobic rod bacillus
2 forms – vegetative and sporeforming
Strains – Type A (diarrhoea)
- Type C (‘pig-bel’)
Clostridium botulinum
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Principal symptoms
• Weariness, weakness, vertigo, double
vision, difficulty swallowing and
speaking
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Potential food contamination
 Improperly canned or fermented goods
No. of illnesses
 58
No. of deaths
 4
Clostridium botulinum
Botulism & infant
botulism
(& wound botulism)
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The organism –
anaerobic, G+ve,
spore-forming rod
Clostridium botulinum
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Group I – type A, B & F – food
spoilage
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Group II – type B, E & F
Types A, B, E & F – human
botulism
Types C & D – botulism in animals
Clostridium botulinum
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Characteristics
- grows anaerobically
- spores & toxin resist freezing
- spores resist desiccation
Clostridium botulinum
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Pathogenesis
- neurotoxin inhibits acetylcholine
release
- ultimately affects peripheral NS
Clostridium botulinum
Botulinum toxin
inhibits
acetylcholine
release at
neuromuscular
junction
Clostridium botulinum
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The illness, continued
- infective dose – few nanograms
- all individuals susceptible; infants <1yr
- Rx – toxin removal, supportive Rx
Clostridium botulinum
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Sources
- human – no
- animal – can be affected
- food – Type E in seafood, Type A in
vegetables, honey
- environment – Types A, B & F in
soils/sediments
Type E – marine
Dust (vacuum cleaner)
Clostridium botulinum
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Outbreaks/sporadic cases
Very rare in NZ – one case in 1984
– puha & mussels (incomplete lactic acid
fermentation)
Overseas:
- roasted egg plant in oil, chopped garlic in oil,
salted fish, tinned salmon, yoghurt, cheese &
cheese sauce
Bacillus cereus
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Principal symptoms
• Diarrheal—watery diarrhea, abdominal
cramps and pain
• Emetic—nausea and vomiting
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Potential food contamination
• Meats, milk, vegetables, fish 0
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No. of illnesses
• 27,360
No. of deaths
•0
Bacillus cereus
Two syndromes –
diarrhoeal & emetic
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The organism – G+ve sporeforming rod
Toxins – diarrhoeal &
emetic
Bacillus cereus
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Characteristics
- rapid growth in food at 30-400C
- vegetative cells killed by heat
- spores resistant, emetic toxins
resistant to heat