Food Borne Food Borne IllnessIllness

Food Borne IllnessFood Borne Illness Food Borne Illness Can be caused by:Food Borne Illness Can be caused by:

• Food Borne Infections ( Living organisms )Food Borne Infections ( Living organisms )• Food Borne Toxins ( non living chemicals )Food Borne Toxins ( non living chemicals )

Food PoisoningFood Poisoning• Food Borne Toxins ( non living chemicals )Food Borne Toxins ( non living chemicals )• Generated by MicrobesGenerated by Microbes

BacteriaBacteria FungiFungi AlgeaAlgea

• Man made toxinsMan made toxins Agricultural residuesAgricultural residues Antibiotics Antibiotics PreservativesPreservatives

• Naturally occuring toxinsNaturally occuring toxins

Bacterial Food PoisoningBacterial Food Poisoning

Toxins that are destroyed by Toxins that are destroyed by heatingheating         Clostridium botulinum         Clostridium botulinum

Heat stable toxinsHeat stable toxins         Produced by bacteria         Produced by bacteria            Staphylococcus aureus            Staphylococcus aureus            Clostridium perfringens            Clostridium perfringens            Bacillus cereus            Bacillus cereus

Food Borne InfectionsFood Borne Infections Causes by Bacteria that must grow in Causes by Bacteria that must grow in

food before eatenfood before eaten• Require large infective dosageRequire large infective dosage

Only BacteriaOnly Bacteria

Caused by Organism that do not have to Caused by Organism that do not have to grow in the food before it is eatengrow in the food before it is eaten• Require small infective dosageRequire small infective dosage

BacteriaBacteria VirusesViruses ParasitesParasites

Staphylococcus aureusStaphylococcus aureusStaphylococcal InfectionsStaphylococcal Infections

• Gram-positive cocci in irregular clustersGram-positive cocci in irregular clusters• Coagulase negative strains make up to 90% of Coagulase negative strains make up to 90% of

skin microbiota (skin microbiota (S. epidermidisS. epidermidis). Only pathogenic ). Only pathogenic when skin is broken or through invasive entry.when skin is broken or through invasive entry.

• Coagulase positive strains tend to be pathogenicCoagulase positive strains tend to be pathogenic. . Almost all pathogenic Almost all pathogenic S. aureusS. aureus strains make strains make coagulase. High correlation between ability to coagulase. High correlation between ability to produce coagulase and production of damaging produce coagulase and production of damaging toxinstoxins::

LeukocidinLeukocidin: Destroys phagocytic white blood cells.: Destroys phagocytic white blood cells. Exfoliative toxinExfoliative toxin: Responsible for scalded skin : Responsible for scalded skin

syndrome.syndrome. EnterotoxinsEnterotoxins: Affect gastrointestinal tract.: Affect gastrointestinal tract.

• S. aureusS. aureus is commonly found in nasal passages. is commonly found in nasal passages.

Staphylococcal Food PoisoningStaphylococcal Food PoisoningCharacteristics:Characteristics: Acute onset of cramps, vomiting, Acute onset of cramps, vomiting,

nausea, occasional diarrhea, low body nausea, occasional diarrhea, low body temperature and blood pressure. temperature and blood pressure.

Recovery is usually complete within 24 Recovery is usually complete within 24 hours. hours.

Mortality is low in healthy individuals, Mortality is low in healthy individuals, higher among immunosuppressed higher among immunosuppressed individuals.individuals.

PathogensPathogens: : S. aureus S. aureus strainstrain that produces that produces an enterotoxin.an enterotoxin.

ReservoirReservoir: Human skin, nasal secretions, : Human skin, nasal secretions, and cow milk. and cow milk.

•On Manitol salt agar

Heamolysis on HBA

Staph Poisoning in USA 2000Staph Poisoning in USA 2000 Principal symptomsPrincipal symptoms

• Nausea, vomiting, retching, abdominal Nausea, vomiting, retching, abdominal cramps, prostrationcramps, prostration

Potential food contamination Potential food contamination

• Meat and meat products, poultry, eggMeat and meat products, poultry, egg• salads (chicken, potato, macaroni),salads (chicken, potato, macaroni),• cream-filled bakery products, milk and cream-filled bakery products, milk and

dairy productsdairy products No. of illnesses No. of illnesses

• 185,060185,060 No. of deaths No. of deaths

• 22

Micro & Macroscopic C. perfringens

NOTE: Large rectangular gram-positive bacilli

Inner beta-hemolysis = θ toxin Outer alpha-hemolysis = α toxin

NOTE: Double zone of hemolysis

Clostridial Cellulitis

Exotoxins Associated with C. perfringens Types A-E

Major

Perfringens Poisoning in USA Perfringens Poisoning in USA 20002000

Principal symptomsPrincipal symptoms Intense abdominal cramps, Intense abdominal cramps,

diarrheadiarrhea Potential food contaminationPotential food contamination

Meat, meat products, graviesMeat, meat products, gravies No. of illnessesNo. of illnesses

248,520248,520 No. of deathsNo. of deaths

77

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’)

Clostridium botulinumClostridium botulinum

Principal symptomsPrincipal symptoms • Weariness, weakness, vertigo, double Weariness, weakness, vertigo, double

vision, difficulty swallowing and vision, difficulty swallowing and speakingspeaking

Potential food contaminationPotential food contamination Improperly canned or fermented goodsImproperly canned or fermented goods

No. of illnessesNo. of illnesses 5858

No. of deathsNo. of deaths 44

Clostridium botulinum

Botulism & infant botulism

(& wound botulism)

The organism – anaerobic, G+ve, spore-forming rod

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

Clostridium botulinum

Characteristics

- grows anaerobically - spores & toxin resist freezing - spores resist desiccation

Clostridium botulinum

Pathogenesis - neurotoxin inhibits acetylcholine release - ultimately affects peripheral NS

Clostridium botulinum

Botulinum toxin

inhibits acetylcholine

release at

neuromuscular junction

Clostridium botulinum

The illness, continued

- infective dose – few nanograms - all individuals susceptible; infants

<1yr - Rx – toxin removal, supportive Rx

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)

Clostridium botulinum

Outbreaks/sporadic casesVery 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 cereusBacillus cereus

Principal symptomsPrincipal symptoms • Diarrheal—watery diarrhea, abdominal Diarrheal—watery diarrhea, abdominal

cramps and paincramps and pain• Emetic—nausea and vomitingEmetic—nausea and vomiting

Potential food contaminationPotential food contamination

• Meats, milk, vegetables, fish 0Meats, milk, vegetables, fish 0 No. of illnessesNo. of illnesses

• 27,36027,360 No. of deathsNo. of deaths

• 00

Bacillus cereus

Two syndromes – diarrhoeal & emetic

The organism – G+ve spore-forming rod

Toxins – diarrhoeal & emetic

Bacillus cereus

Characteristics

- rapid growth in food at 30-400C

- vegetative cells killed by heat - spores resistant, emetic toxins resistant to heat