Food Poisoning

Question 1

Where do bacteria causing human food poisoning come from?

Answer 1

-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

Question 2

Symptoms of food poisoning

Answer 2

Fever
Abdominal pain
Diarrhoea
Vomiting

Question 3

Name the 2 food poison types

Answer 3

Infection- type
Toxin- type

—food poisons

Question 4

Describe the 2 food poison types

Answer 4

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

Question 5

What is non-typhoidal Salmonella?

Answer 5

Salmonella acquired from animals via food

Question 6

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?

Answer 6

-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.

Question 7

When and why is the capsule of the campylobacter produced?

Answer 7

Produced when organism is in gut, especially when there’s blood in gut so it protects itself

Question 8

What does microaerophilic mean?

Answer 8

Requires low levels of O2

Question 9

Which is the most important bacterial food borne pathogen throughout the world?

Answer 9

Campylobacter

Question 10

What bacteria is the most frequently identified cause of acute infective bacterial diarrhoea in humans?

Answer 10

Campylobacter

Question 11

Where is campylobacter acquired from?

Answer 11

Food

Question 12

There are thousands of salmonella serotypes but which are the 2 species of salmonella that are identified genetically?

Answer 12

S. Enterica (pathogenic) and S. Bongori (not pathogenic)

Question 13

Sources of salmonella

Answer 13

-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

Question 14

S.enteritidis PT4 (phage-type 4)
-where is it found
-can invade the…
-contaminates interior of what

Answer 14

-found in poultry, eggs
-invades oviduct
-interior of eggs contaminated

Question 15

Enterohaemorrhagic E.coli (EHEC)
-found in what foods
-its reservoirs
-does it make carrier normal sick?
-meat becomes contaminated during what process?

Answer 15

-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

Question 16

Botulism disease
-caused by what organism; gram neg or pos?
-how does it occur
-where does this occur

Answer 16

-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

Question 17

Which animal is most responsible for campylobacter food poisoning cases

Answer 17

Poultry

Question 18

What does serotypes mean

Answer 18

Antigenic variants of a species

Question 19

How do you get different serotypes of salmonella

Answer 19

All the different sugars (LPS) of O antigen and flagella antigenic variation

Question 20

How do we distinguish the serotypes of salmonella in a lab

Answer 20

Agglutination reaction; tells you what the serotypes is

Question 21

How do we sub divide a serotypes

Answer 21

-By phage typing
-Pulse field electrophoresis; old fashioned

Question 22

What are the different types of neurotoxin botulinum

Answer 22

A, B, C, D, E, F, G

Question 23

Describe the botulinum toxin and the process it undergoes to results in FLACCID paralysis

Answer 23

-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

Question 24

Spores of clostridium botulinum are very…what does this mean

Answer 24

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

Question 25

Clostridium perfringens bacteria -get from what -gram neg or pos? -resist what? -what does it cause in body and how does it accomplish this

Answer 25

-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