FOODBORNE INTOXICATIONS

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FOOD-BORNE INTOXICATIONS

• Vibrio cholerae, Staphylococcus aureus,
  Clostridium perfringens

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Vibrio cholerae

• Asiatic or epidemic cholera
• The organism motile rod with single sheathed
  flagellum
• Serotypes O 1 (classical El Tor)
• O 139 (Bengal)
• Toxin CT (cholera toxin)

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Vibrio cholerae

• Characteristics
• - survive freezing changes to VBNC
• CCPs hurdles
• - inactivated by heat, low pH, desiccation
• radiation
• (Vibrio organisms are not removed by depuration)

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Terms

• D value (decimal reduction value)
• time required to inactivate 90 of
• organism population at given temperature
• VBNC state (viable but non-culturable)
• cells remain viable but cannot be cultured
  
• reversal to metabolically active
  culturable state possible
• Depuration
• cleansing of shellfish by transfer to
  clean water

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Vibrio cholerae

• Pathogenesis
• - bacteria attach to sm. intestine
  wall produce CT
• toxin
• - CT toxin - fragment A increases
  intracellular cAMP
• - fragment B adherence
  to cells
• - hypersecretion characteristic
  diarrhoea

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Vibrio cholerae

• Pathogenesis

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Vibrio cholerae

• The illness
• - incubation 6hrs to 5 days
• - sudden onset of vomiting
• painless diarrhoea
• - rice water stools
• - severe dehydration death

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Vibrio cholerae

• The illness, continued
• - infective dose 1 mill.
• - all individuals susceptible
• - Rx rehydration electrolyte repl.

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Vibrio cholerae

• Sources
• - human primary reservoirs/carriers
• - animal - zooplankton
• - food mainly seafood
• - environment aquatic reservoirs

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Vibrio cholerae

• Outbreaks/incidents
• NZ
• - very few in NZ
• - non O 1/O 139 Bay of
• Plenty
• Overseas
• - coconut milk, canned
• palm fruit, seafood salad,
• crab meat, raw oysters, rice

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Staphylococcus aureus

• Staphyloenterotoxicosis or enterotoxaemia
• The organism Gve spherical coccus pairs,
  short chains, or grape-like clusters
• Enterotoxins emetic pyrogenic

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Staphylococcus aureus

• Characteristics
• - resists desiccation destroyed by
• cooking pasteurization
• (Staphylococcal enterotoxins are extremely
  heat-stable)

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Staphylococcus aureus

• CCPs hurdles
• - inactivated by heat, low pH, common
• preservation methods UV radiation

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Staphylococcus aureus

• Pathogenesis
• - preformed enterotoxins emetic
  pyrogenic
• - binding site in intestines unknown
• - resistant to proteolytic enzymes
• - stimulate gut vagus sympathetic
  nerves

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Staphylococcus aureus

• The illness
• - incubation 0.5 to 7 hours
• - rapid onset nausea, retching,
• vomiting, abdominal cramping,
  diarrhoea
• - severe cases headache, fever,
• muscular cramping, prostration

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Staphylococcus aureus

• The illness, continued
• - infective dose - lt 1 micro gm toxin
• - all individuals susceptible
• - no Rx (recovery in 2 days)

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Staphylococcus aureus

• Sources
• - human main reservoir
• - animal cattle, pigs, chickens,
  turkeys
• - food mainly cooked foods
• - environment food processing
  equipment,
• 
  ventilation dust

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Staphylococcus aureus

• Outbreaks/incidents
• Time/temperature abuse after preparation of food
• NZ
• yoghurt, hot ham sandwiches, Christmas
• hams, freeze-dried trampers meals
• Overseas
• - baked ham, chicken salad, hot turkey
• sandwiches, lasagna pasta

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Clostridium perfringens

• Two syndromes diarrhoea and pig-bel
  (necrotizing enteritis)
• The organism large, non-motile Gve, anaerobic
  rod - bacillus
• 2 forms vegetative and spore-forming
• Strains Type A (diarrhoea)
• - Type C (pig-bel)

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Clostridium perfringens

• The organism/toxin
• Anaerobic, G spore-forming rod
• Toxin CPE - spore-forming phase in
• intestine

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Clostridium perfringens

• Characteristics
• - vegetative cells killed by heat cold
• - spores resistant to heat, cold
• desiccation

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Clostridium perfringens

• CCPs hurdles
• - cells enterotoxin inactivated by heat
• - cells do not grow at lt12 0 C NB CCP
• - spores inactivated by ethanol
  radiation

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Clostridium perfringens

• Pathogenesis
• - vegetative cells survive stomach
  passage
• - sporulate in sm. int. release CPE
• - site of action villus tip
• - action reversal of net transport
• resulting in H20, Cl- and Na
  secretion

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Clostridium perfringens

• The illness
• - incubation approx. 12 hours
• - intense abdominal cramps
• - profuse diarrhoea
• - pig-bel s. int. gangrene, toxaemia
  
• death

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Clostridium perfringens

• The illness, continued
• - infective dose 1 mill. cells/gm of
  food
• - all individuals susceptible
• - no Rx (recovery in 24 hours)

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Clostridium perfringens

• Sources
• - human - no
• - animal food animals (normally in
• 
  intestines)
• - food cooked meat poultry
• - environment soil, dust, vegetation

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Clostridium perfringens

• Outbreaks/incidents
• Improper refrigeration of large portions of
  cooked food
• NZ
• roast turkey rolls, Chicken a la King,
  roast
• pork, wontons, roast chicken with
  stuffing
• Overseas
• - gravy, chicken vol-au-vent, roast lamb,
  
• roast pork, minestrone soup,
  spinach/fried
• bean curd