Food Poisoning Flashcards
Where do bacteria causing human food poisoning come from?
-Pathogens/non pathogens from animals e.g salmonella
-Commensals (part of micro biome of older animals) e.g EHEC (carried by cattle but causes no disease in them however does cause disease in humans) , campylobacter
-Microorganisms may be introduced into or on food surface e.g Clostridium botulinum
Symptoms of food poisoning
Fever
Abdominal pain
Diarrhoea
Vomiting
Name the 2 food poison types
Infection- type
Toxin- type
—food poisons
Describe the 2 food poison types
Infection-type food poisoning->organism ingested and interact with mucosal surfaces; produce toxin which is responsible for symptoms of diarrhoea or invade into tissue which induces inflammation and often cause bloody diarrhoea
-Salmonella, Campylobacter, E. coli (Listeria monocytogenes)
Toxin-type food poisoning-> ingest food containing toxin and its toxin that gives clinical symptoms
-Staphylococcus aureus - enterotoxin
-Clostridium botulinum – neurotoxin
What is non-typhoidal Salmonella?
Salmonella acquired from animals via food
Campylobacter
-2 main pathogens and where they are most commonly found
-characteristics of structure
-gram neg or pos? Rods or circles?
-do they need O2 for growth?
-C.jejuni (commonly present in chickens and other like cattle sheep pigs) & C.coli (most commonly in pigs)
-slender, motile, gram negative curved or spiral rods with a capsule
- no they are microaerophilic. Needs ^ CO2 and reduced levels of O2 to grow.
When and why is the capsule of the campylobacter produced?
Produced when organism is in gut, especially when there’s blood in gut so it protects itself
What does microaerophilic mean?
Requires low levels of O2
Which is the most important bacterial food borne pathogen throughout the world?
Campylobacter
What bacteria is the most frequently identified cause of acute infective bacterial diarrhoea in humans?
Campylobacter
Where is campylobacter acquired from?
Food
There are thousands of salmonella serotypes but which are the 2 species of salmonella that are identified genetically?
S. Enterica (pathogenic) and S. Bongori (not pathogenic)
Sources of salmonella
-Live in food animals GI tract (salmonella food poisoning serotypes)
-Cross-contamination
-Inadequate cooking and storage at a temp suitable for growth
-S. Enteritidis PT4 (phage-type 4) - vertical transmission in poultry from infected adult -> egg -> chick ->infected adult
S.enteritidis PT4 (phage-type 4)
-where is it found
-can invade the…
-contaminates interior of what
-found in poultry, eggs
-invades oviduct
-interior of eggs contaminated
Enterohaemorrhagic E.coli (EHEC)
-found in what foods
-its reservoirs
-does it make carrier normal sick?
-meat becomes contaminated during what process?
-Hamburgers, raw potatoes, raw milk etc
-intestine of cattle mostly but also chickens, deer, sheep and pigs
-doesn’t make carrier sick
-during slaughtering process
Botulism disease
-caused by what organism; gram neg or pos?
-how does it occur
-where does this occur
-caused by clostridium botulinum; gram positive
- Bacteria produces a botulinum neurotoxin that attacks body’s nerve and causes difficult breathing, muscle paralysis and even death
-occurs in rotting carcasses, decaying vegetation and contaminated canned food
Which animal is most responsible for campylobacter food poisoning cases
Poultry
What does serotypes mean
Antigenic variants of a species
How do you get different serotypes of salmonella
All the different sugars (LPS) of O antigen and flagella antigenic variation
How do we distinguish the serotypes of salmonella in a lab
Agglutination reaction; tells you what the serotypes is
How do we sub divide a serotypes
-By phage typing
-Pulse field electrophoresis; old fashioned
What are the different types of neurotoxin botulinum
A, B, C, D, E, F, G
Describe the botulinum toxin and the process it undergoes to results in FLACCID paralysis
-made up of light and heavy chain. It is a protease toxin
-toxin in the food; absorbed into blood stream and acts at neuromuscular junctions
-prevents acetylcholine release at neuromuscular junctions this means nerve impulses cannot be passed on (muscles go floppy) and results in FLACCID paralysis
Spores of clostridium botulinum are very…what does this mean
Heat resistant; Sterilising the food doesn’t stop them from persisting and doesn’t kill them in the food. Therefore spores germinate, vegetative organism grow. And bacteria produces the toxin that humans ingest
Clostridium perfringens bacteria
-get from what
-gram neg or pos?
-resist what?
-what does it cause in body and how does it accomplish this
-causes food poisoning
-get from meat and poultry- faecal contamination at slaughter
-gram positive
-resist heating and can germinate if food stored inadequately
-causes diarrhoea and abdominal cramps by
1. Forming pores in epithelial membrane plasma membranes; makes cell leaky and cell contents leak out
2. Acts at tight junctions; they become leaky which means you can’t absorb fluid and it seeps out, coming out as diarrhoea
