Human foodborne diseases Flashcards
What is a food borne infection?
An agent (bacteria/virus) that results in disease
What is food poisoning?
The exposure to toxins that results in disease
Food-borne infections are often zoonotic. Give examples of food-borne infections
Salmonella
E.coli
Norovirus
Food poisoning is often caused by contamination, poor handling or storage. What are examples of food poisonings?
Staphylococcus toxin
Bacillus enterotoxin
Afalotoxins from fungi
What is the difference in onset between food poisoning and food-borne infections?
Food poisoning faster onset - can be minutes
Food-borne infection can be days
Why is it becoming increasingly difficult to feed the population?
Increased population
Need sustainable options
Increase supply and choice
How do microbes survive on food so well?
Attach to food/preparation surface
Replicate to form biofilm
Biofilm tourer than individual bugs and disinfection
What do bacterial toxins cause?
Exotoxins produced by bacteria cause food poisoning
What bacterial toxins induce vomiting and diarrhoea?
Emetic toxins = V+
Enterotoxins = D+
What foods may have Salmonella enterica on them?
Meat
Eggs
Milk
Faecal contaminated fruit/veg
What are the symptoms of Salmonella enterica?
Gastroenteritis
V+, D+
What foods may host E.coli?
Beef
Milk
Faecal contaminated fruit/veg
What symptoms does pathogenic E.coli cause?
Haemorrhagic diarrhoea
Renal failure
What are some of the pathotypes of E.coli?
Enteropathogenic
Enterotoxigenic
Enterohaemorrhagic
What foods host Campylobacter?
Meat
Mainly chicken
What is the most common food borne disease in UK? (also most worldwide cause of gastroenteritis)
Campylobacter
What type of bacteria is campylobacter? Gram? Shape? Air? Temperature
Gram -ve
Rod shaped
Microaerophilic
Slightly thermophilic (41 - body T of chicken)
Symptoms for campylobacter occur within 2-5 days. Who are the main risk groups?
Elderly, young
Bowel cancer patients
People on proton pump inhibiting drugs (increased gastric pH can’t destroy bacteria)
Why are chicken the main source of Campylobacter?
Body T of 41 (thermophilic)
Little oxygen in gut (microaerophilic)
High growth in caeca
High levels of faecal shedding and droppings
What food can host Listeria monocytogenes? What does it cause? (Rare in EU)
Cooked meats, soft cheese, fish
Invasive CNS infection
What type of bacteria (gram) is Listeria? Where is it found?
Gram positivie
Intramacrophage
Most cases of Listeria are mild. When can they be more severe?
Pregnant
Elderly
Immunocompromised
What food hosts Clostridium perfringens? What does it cause?
Poorly cooked/stored meat
Gastroenteritis
What type of bacteria (Gram) is clostridium? What shape are they?
Gram positive
Rods
Spore forming - severe
What pathogen is caused by poorly canned food. What do these bacteria have that allow it to grow in these conditions?
Clostridium botulinum
Spores
What does the toxin from Clostridium botulinum do??
Block synapses
Causes paralysis and death
Hepatitis E is a virus from what foods? What does it cause? Is it severe?
Pork
Hepatitis - short lived, self-limiting. Can be fatal
Foodborne norovirus is the 2nd most common food borne disease in the UK. What foods cause it? What does it cause?
Many sources including seafood
Gastroenteritis
How many species of Shigella are there? What do they cause?
4 (some produce shiga toxins)
Human dysentry
How is Shigella transmitted?
Food-borne
Or between people
What type of bacteria is Bacillus cereus (gram, shape, does it form toxins)
Gram +ve
Spore forming rod
Produces 2 toxins
What foods are associated with Bacillus cereus?
Pulses
Rice
When do Bacillus cereus spores germinate? Can their toxins be killed by reheating?
If food not chilled
No
What are the 2 toxins produced by Bacillus cereus and what do they cause?
Emetic = V+ Enteric = profuse, painful D+
