INFECTIOUS AGENTS - Food Poisoning (Enteritis) and Gastrointestinal Bacteria

Question 1

Why is food poisoning a concern within veterinary public health?

Answer 1

Food poisoning is one of the most common zoonotic diseases acquired from humans from animals and their products (food)

Question 2

Define the term ‘food poisoning’

Answer 2

Any disease of an infectious or toxic nature, caused by or thought to be caused by the consumption of food or water

Question 3

What are the typical clinical signs of human food poisoning?

Answer 3

• Pyrexia
• Abdominal pain
• Diarrhoea
• Vomiting

Question 4

What are the two most significant bacteria which cause infection-type human food poisoning in the UK?

Answer 4

Salmonella
Campylobacter

Question 5

What are the two most significant pathogens which cause infection-type human food poisoning in the US?

Answer 5

• Norovirus
• Salmonella

Question 6

What are the two most significant bacteria which cause toxic-type human food poisoning?

Answer 6

• Staphylococcus aureus (enterotoxin)
• Clostridium botulinum (neurotoxin)

Question 7

What is the more frequently identified cause of acute bacterial diarrhoea in humans?

Answer 7

Campylobacter

Question 8

Which species of Campylobacter infect chickens?

Answer 8

Campylobacter jejuni (C. jejuni)

Question 9

Which species of Campylobacter infects pigs?

Answer 9

Campylobacter coli (C. coli)

Question 10

Describe the structure of the Campylobacter bacteria

Answer 10

Motile, slender, curved or spiral rods (bacilli)

Question 11

Are Campylobacter Gram positive or Gram negative bacteria?

Answer 11

Campylobacter are Gram negative bacteria

Question 12

(T/F) Campylobacter do not require O2 to grow

Answer 12

FALSE. Campylobacter are obligative aerobes and thus require O2 to grow

Question 13

What is the most common cause of Campylobacter transmission?

Answer 13

The ingestion of undercooked meat that has been contaminated by the animals intestinal contents during butchering

Question 14

(T/F) Campylobacter is commonly transmitted between humans

Answer 14

FALSE. Campylobacter is very rarely transmitted between humans however is more common in children

Question 15

Define the term ‘serotypes’

Answer 15

Serotypes are the groups within a single species of a microorganism which share distinctive surface structures

Question 16

What are the two species of Salmonella?

Answer 16

Salmonella bongori (S. bongori)
Salmonella enterica (S. enterica)

Question 17

Are Salmonella Gram positive or Gram negative bacteria?

Answer 17

Salmonella are Gram negative bacteria

Question 18

Which species of Salmonella is pathogenic?

Answer 18

Salmonella enterica (S. enterica)

Question 19

Which species of Salmonella includes all of the clinically important serotypes?

Answer 19

All of the clinically important strains of Salmonella in humans and animals are serotypes of S. enterica as this is the pathogenic species of Salmonella

Question 20

What do the O and H antigens code for in Salmonella serotyping?

Answer 20

• ‘O’ antigen codes for the lipopolysaccharide (LPS)
• ‘H’ antigen codes for the flagella

Question 21

Which test can be used to determine a Salmonella stereotype?

Answer 21

Slide agglutination test

Question 22

What can be used to sub-divide a salmonella serotype?

Answer 22

Gel electrophoresis

Question 23

What clinical disease is caused by Salmonella infection?

Answer 23

Usually localised gastroenteritis but Salmonella can also cause systemic infections such as sepsis

Question 24

Describe how Salmonella enteritidis PD4 undergoes vertical transmission in poultry

Answer 24

S. enteritidis PD4 infects the adult hen and infects the oviduct, allowing the bacteria to infect the egg. This then results in infection of the chick which will be a carrier of the bacteria for further infection

Question 25

What does ETEC stand for?

Answer 25

Enterotoxigenic E. coli (ETEC)

Question 26

What does EPEC stand for?

Answer 26

Enteropathogenic E. coli (EPEC)

Question 27

What does EHEC stand for?

Answer 27

Enterohaemorrhagic E-coli (EHEC)

Question 28

Where in the body of the host is Enterohaemorrhagic E-coli (EHEC) found?

Answer 28

The intestines of cattle

Question 29

List two of the food poisoning inducing bacteria which form endospores

Answer 29

• Clostridium botulinum
• Clostridium perfringens

Question 30

What is the name of the bacteria which causes Botulism?

Answer 30

Clostridium botulinum

Question 31

(T/F) Clostridium botulinum is a Gram negative bacteria

Answer 31

FALSE. Clostridium botulinum is a Gram positive bacteria

Question 32

What type of paralysis is caused by Botulism?

Answer 32

Flaccid paralysis

Question 33

Describe the pathogenesis of Clostridium botulinum causing Botulism

Answer 33

Clostridium botulinum secretes a neurotoxin known as botulinum toxin. If the host consumes infected food, this neurotoxin can be absorbed through the gut wall and into the bloodstream. Botulinum toxin acts on the neuromuscular junctions of cholinergic neurones preventing the release of acetylcholine leading to flaccid paralysis

Question 34

How does Botulism usually kill the host?

Answer 34

The botulinum toxin paralyses respiratory muscles causing the infected host to suffocate

Question 35

Which bacteria is the 3rd most common cause of food poisoning in the UK?

Answer 35

Clostridium perfringens

Question 36

(T/F) Clostridium perfringens is a Gram positive bacteria

Answer 36

TRUE

Question 37

How does Clostridium perfringens cause diarrhoea?

Answer 37

Through altering the membrane permeability of the small intestinal wall. This can be done in two possible ways:
1. The formation of pores in the plasma membrane of the small intestinal epithelial cells
2. The disruption of the tight junctions of the small intestinal epithelial cells