Food Borne Illness

1. Food Borne Illness

2. Food Borne Illness • Food Borne Illness Can be caused by: • Food Borne Infections ( Living organisms ) • Food Borne Toxins ( non living chemicals ) • Food Poisoning • Food Borne Toxins ( non living chemicals ) • Generated by Microbes • Bacteria • Fungi • Algea • Man made toxins • Agricultural residues • Antibiotics • Preservatives • Naturally occuring toxins

3. Bacterial Food Poisoning • Toxins that are destroyed by heatingClostridium botulinum • Heat stable toxins        Produced by bacteria Staphylococcus aureusClostridium perfringensBacillus cereus

4. Food Borne Infections • Causes by Bacteria that must grow in food before eaten • Require large infective dosage • Only Bacteria • Caused by Organism that do not have to grow in the food before it is eaten • Require small infective dosage • Bacteria • Viruses • Parasites

5. 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: • 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.

6. Staphylococcal Food Poisoning Characteristics: • Acute onset of cramps, vomiting, nausea, occasional diarrhea, low body temperature and blood pressure. • Recovery is usually complete within 24 hours. • Mortality is low in healthy individuals, higher among immunosuppressed individuals. • Pathogens: S. aureus strainthat produces an enterotoxin. • Reservoir: Human skin, nasal secretions, and cow milk.

7. On Manitol salt agar Heamolysis on HBA

8. Staph Poisoning in USA 2000 • Principal symptoms • Nausea, vomiting, retching, abdominal cramps, prostration • Potential food contamination • Meat and meat products, poultry, egg • salads (chicken, potato, macaroni), • cream-filled bakery products, milk and dairy products • No. of illnesses • 185,060 • No. of deaths • 2

9. NOTE:Large rectangular gram-positive bacilli NOTE:Double zone of hemolysis Inner beta-hemolysis = θ toxin Outer alpha-hemolysis = α toxin Micro & Macroscopic C. perfringens

10. Clostridial Cellulitis

11. Exotoxins Associated with C. perfringens Types A-E Major

12. Perfringens Poisoning in USA 2000 • Principal symptoms Intense abdominal cramps, diarrhea • Potential food contamination • Meat, meat products, gravies • No. of illnesses • 248,520 • No. of deaths • 7

13. Clostridium perfringens Two syndromes– diarrhoea and ‘pig-bel’(necrotizing enteritis) • The organism –large, non-motile G+ve, anaerobic rod - bacillus 2 forms – vegetative and spore-forming • Strains – Type A (diarrhoea) - Type C (‘pig-bel’)

14. Clostridium botulinum • Principal symptoms • Weariness, weakness, vertigo, double vision, difficulty swallowing and speaking • Potential food contamination • Improperly canned or fermented goods • No. of illnesses • 58 • No. of deaths • 4

15. Clostridium botulinum Botulism & infant botulism (& wound botulism) • The organism – anaerobic, G+ve, spore-forming rod

16. Clostridium botulinum • Group I –type A, B & F – food spoilage Group II –type B, E & F • Types A, B, E & F – human botulism Types C & D –botulism in animals

17. Clostridium botulinum • Characteristics - grows anaerobically - spores & toxin resist freezing - spores resist desiccation

18. Clostridium botulinum • Pathogenesis - neurotoxin inhibits acetylcholine release - ultimately affects peripheral NS

19. Clostridium botulinum Botulinum toxin inhibits acetylcholine release at neuromuscular junction

20. Clostridium botulinum • The illness, continued - infective dose – few nanograms - all individuals susceptible; infants <1yr - Rx – toxin removal, supportive Rx

21. Clostridium botulinum • 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)

22. Clostridium botulinum • 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

23. Bacillus cereus • Principal symptoms • Diarrheal—watery diarrhea, abdominal cramps and pain • Emetic—nausea and vomiting • Potential food contamination • Meats, milk, vegetables, fish 0 • No. of illnesses • 27,360 No. of deaths • 0

24. Bacillus cereus Two syndromes – diarrhoeal & emetic • The organism –G+ve spore-forming rod • Toxins – diarrhoeal & emetic

25. Bacillus cereus • Characteristics - rapid growth in food at 30-400C - vegetative cells killed by heat - spores resistant, emetic toxins resistant to heat