034 Bacterial infections of the gut Flashcards
Which group of antibiotics slows the GI tract down?
Codeine groups
What are some benefits of normal bacteria flora?
Production of antibacterial substances
Interference with virulence of pathogens
Aid development of intestinal immunity
Resist colonisation of pathogens
What are mucins?
Glycoproteins secreted and membrane bound forms. Produced by goblet cells in epithelium.
Where do we mainly find anaerobes in the gut tract?
Lower down
Where are gram positive bacteria normally located along the GI tract?
Upper GI tract e.g. stomach.
Which cells in the GI tract produce antimicrobial peptides?
Paneth cells
What are M cells?
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.
Where are peyers patches located?
In the mucosa and extend into the submucosa of small intestine especially the ileum.
How many Shigella bacteria does it take to cause an infection?
10-100
Name 3 types of pathogenesis of GI pathogen bacteria
Toxin release
Adhesion to gut mucosa
Tissue invasion
Name a significant neurotoxin
Botulinum toxin
What is the function of peyers patches?
This produces antibodies and there is transport of secretory IgA into the lumen
Name 3 types of toxins
Neurotoxins
Enterotoxins
Cytotoxins
Which toxin produces secretory diarrhoea
Enterotoxins
Which toxin produces tissue damage?
Cytotoxin
What is the pathogenesis of the botulinum toxin?
When endocytosed, it ccleaves proteins needed for ACh release at neuromuscular junction. This causes muscle weakness supplied by cranial nerves.
Name a significant enterotoxin
Cholera toxin
What is the pathogenesis of the cholera toxin?
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.
Name a significant cytotoxin
Shigella dysenteriae
What is the pathogenesis of shigella dysenteriae
Halts protein synthesis by binding RNA in ribosomes.
What is adherance mediated by?
Fimbriae and adhesins
What is the main treatment for GI infection bacterial?
Rehydration - antibiotics are not used unless they are in risk group. Azithromycin/Ciprofloxacin (for Salmonella and Campylobacter)
What is the most common cause of bacterial gastroenteritis in the UK?
Campylobacter
What are symptoms of campylobacter?
Fever, diarrhoea, abdominal pain
How do we diagnose for S.aureus?
Sample of vomit
Which type of salmonella presents with headache/rashes etc?
Typhoidal (S.typhi)
Which type of salmonella presents with typical gastro enteritis?
Non-typhoidal disease
What is the one typical strain of E.coli associated with more severe disease?
E.coli O157
What are the symptoms of listeria monocytogenes?
Slight GI upset, bacteramia, meningitis
Which infection is the most common cause of antibiotic associated diarrhoea?
Clostridium difficile
