GI Infections Flashcards
What is the main defence against infection in the Gi tract?
Commensals organism/normal gut flora
What are some GI defences?
Sight, smell, memory
Salivary (bacteriostatic secretions)
Gastric acid
Bile
Colonic mucus
Anaerobic environment
How does the number of Microbiota change a you progress through the gut?
Proximal gut relatively sterile -> more and more Microbiota
What are the benefits of a micro biome?
Harmful bacteria cant compete for nutrients
Microbiota produce anti microbial substances
Help develop newborns immune system
Produce certain nutrients
What is the main nutrient produced by the micro biome?
Vitamin K
Why are C-section babies more likely to develop infection?
They dont pass all the way through the birth canal so receive less of moms micro biome
How does a less diverse microbiome affect your health?
Obesity more likely
Inflammatory bowel disease
Less likely to respond to chemotherapy
Reduced insulin response to food
What short Chain fatty acids do gut bacteria produce?
Butyrate
Acetate
Propionate
What is the function of the gut bacteria producing the short chain fatty acids like acetate, propionate and butyrate?
Energy source for colonocytes
Cholesterol metabolism (acetate)
Regulating satiety (propionate)
What can affect microbiota in terms of diet and meds?
High fibre (help get rid of bile salts and keeps Microbiota healthy)
Sweeteners (disrupt)
Gluten free diet (without PMH bad)
PPI (inc GI infections)
Antibiotics in meat
Obesity
Probiotics (live bacteria in food)
Prebiotics (food for the Microbiota)
What is a fecal Microbiota transplant?
Take faeces from healthy donors and then give it to sick individuals
Since faces contain many active microbes
How can fecal Microbiota transplants be delivered?
nasogastric tube
Upper GI endoscopy
Colonoscopy
Put in caecum
What disease can Fecal Microbiota transplant be used to treat pretty well?
Clostridium difficile infection
IBD symptoms like Chrons disease
What are the characteristics of the donors for fecal Microbiota transplants?
10 - 25 years
Not having used (last 3months):
-antibiotics
-laxatives
-diet pills
No GI disease
Screened
What are some gram negative bacterial infections of the gut?
Salmonella
Campylobacter
Shigella
Enterotoxigenic ecoli
what is a gram postitive bacteria infection of the GI tract?
Clostridium difficile
What condition does salmonella cause?
Gastroenteritis
What are some symptoms of salmonella infection? (Gastroenteritis)
Nausea
Vomiting
Diarrhoea (mostly non bloody)
Fever
Abdominal cramps
How is salmonella spread?
Ingesting contaminated food or water
What is the pathophysiology of salmonella infection?
Progresses through stomach acid to GI tract
Invades enterocytes (endocytosis)
Body responds which can lead to colitis like presentation
Moves to submucosa and engulfed by macrophages
Macrophages take infection to lymph nodes
Lymphoid hyperplasia
Then they infection can re-enter gut from liver and gall bladder leading to systemic infection
How is salmonella managed?
Usually self limiting )2-3 days)
Fluid resus with electrolytes
How is campylobacter normally spread?
Fecal-oral route usually from poultry
What are the symptoms of campylobacter causing gastroenteritis?
Fever
Abdominal cramps
Diarrhoea (produces cholera like cytotoxin)
How iis campylobacter managed?
Normally self limiting
Fluid/electrolyte replacemtn
Abx if diarrhoea bloody
How is shigella spread?
Infected stools from person to person
What sort of patients does shigella normally infect?
Young children under 5s
What is shigellosis?
A dysentery which normally affects you children
What is the pathophysiology of shigella causing gastroenteritis?
Invades large intestine colonocytes (replaicting and invading neighbouring cells)
Kills colonocytes forming abcesses in mucosa
What are the symptoms of shigella gastroenteritis?
Bloody diarrhoea with mucus
Abdominal cramping
How is shigella usually managed?
Usually self limiting and resolves in a week
What is enterotoxgenic e-coli?
A commensal of the colon but can transform into aa pathogen
How is enterotoxigenic e-coli spread?
Faecal-oral route by contaminated water
What condition does enterotoxigenic e-coli gastroenteritis commonly cause?
Travellers diarrhoea
What is the pathophysiology of enterotoxigenic e-coli infection?
Adheres to enterocyets producing enterotoxins
Enterotoxins cause hypersecretion of chloride ions
Water leaves cells into the gut lumen causing diarrhoea
What is a very good defence against gastroenteritis caused by infection via oral route?
Stomach and the gastric acid
What is the normal route of spread for gram negative Rod bacteria causing gastroenteritis?
Oral route (food, water, faecal)
What symptom do gram negative rod bacterial infections causing gastroenteritis all have?
Diarrhoea
What gram negative bacterial infections causing gastroenteritis produce bloody diarrhoea?
Shigella
Campylobacter
What gram negative bacterial infections causing gastroenteritis produce NON bloody diarrhoea?
Enterotoxigenic e-coli
Salmonella
Why does Shigella nd campylobacter infection lead to bloody diarrhoea?
Affects the large intestine/colon
Why does Enterotoxigenic e-coli and salmonella cause NON bloody diarrhoea?
Usually affects the small intestine
How do all the gram negative rods produce symptoms?
Produce TOXINS