034 Bacterial infections of the gut

Question 1

Which group of antibiotics slows the GI tract down?

Answer 1

Codeine groups

Question 2

What are some benefits of normal bacteria flora?

Answer 2

Production of antibacterial substances
Interference with virulence of pathogens
Aid development of intestinal immunity
Resist colonisation of pathogens

Question 3

What are mucins?

Answer 3

Glycoproteins secreted and membrane bound forms. Produced by goblet cells in epithelium.

Question 4

Where do we mainly find anaerobes in the gut tract?

Answer 4

Lower down

Question 5

Where are gram positive bacteria normally located along the GI tract?

Answer 5

Upper GI tract e.g. stomach.

Question 6

Which cells in the GI tract produce antimicrobial peptides?

Answer 6

Paneth cells

Question 7

What are M cells?

Answer 7

These sit on the gut epithelium and endocytose protein and peptide antigens to transport them into underlying tissues to be taken up by dendritic cells and macrophages. These cells also present to T cells of the GALT to produce IgA secreting plasma cells in mucosa.

Question 8

Where are peyers patches located?

Answer 8

In the mucosa and extend into the submucosa of small intestine especially the ileum.

Question 9

How many Shigella bacteria does it take to cause an infection?

Answer 9

10-100

Question 10

Name 3 types of pathogenesis of GI pathogen bacteria

Answer 10

Toxin release
Adhesion to gut mucosa
Tissue invasion

Question 11

Name a significant neurotoxin

Answer 11

Botulinum toxin

Question 12

What is the function of peyers patches?

Answer 12

This produces antibodies and there is transport of secretory IgA into the lumen

Question 13

Name 3 types of toxins

Answer 13

Neurotoxins
Enterotoxins
Cytotoxins

Question 14

Which toxin produces secretory diarrhoea

Answer 14

Enterotoxins

Question 15

Which toxin produces tissue damage?

Answer 15

Cytotoxin

Question 16

What is the pathogenesis of the botulinum toxin?

Answer 16

When endocytosed, it ccleaves proteins needed for ACh release at neuromuscular junction. This causes muscle weakness supplied by cranial nerves.

Question 17

Name a significant enterotoxin

Answer 17

Cholera toxin

Question 18

What is the pathogenesis of the cholera toxin?

Answer 18

Toxin has B and A subunit. B binds to the cell and A enters the cell. It activated adenyl cyclase causing release of Cl- ions and water follows, leading to secretory diarrhoea.

Question 19

Name a significant cytotoxin

Answer 19

Shigella dysenteriae

Question 20

What is the pathogenesis of shigella dysenteriae

Answer 20

Halts protein synthesis by binding RNA in ribosomes.

Question 21

What is adherance mediated by?

Answer 21

Fimbriae and adhesins

Question 22

What is the main treatment for GI infection bacterial?

Answer 22

Rehydration - antibiotics are not used unless they are in risk group. Azithromycin/Ciprofloxacin (for Salmonella and Campylobacter)

Question 23

What is the most common cause of bacterial gastroenteritis in the UK?

Answer 23

Campylobacter

Question 24

What are symptoms of campylobacter?

Answer 24

Fever, diarrhoea, abdominal pain

Question 25

How do we diagnose for S.aureus?

Answer 25

Sample of vomit

Question 26

Which type of salmonella presents with headache/rashes etc?

Answer 26

Typhoidal (S.typhi)

Question 27

Which type of salmonella presents with typical gastro enteritis?

Answer 27

Non-typhoidal disease

Question 28

What is the one typical strain of E.coli associated with more severe disease?

Answer 28

E.coli O157

Question 29

What are the symptoms of listeria monocytogenes?

Answer 29

Slight GI upset, bacteramia, meningitis

Question 30

Which infection is the most common cause of antibiotic associated diarrhoea?

Answer 30

Clostridium difficile