GI Infections Flashcards by Callum Donoher

What is the main defence against infection in the Gi tract?

Commensals organism/normal gut flora

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What are some GI defences?

Sight, smell, memory
Salivary (bacteriostatic secretions)
Gastric acid
Bile
Colonic mucus
Anaerobic environment

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How does the number of Microbiota change a you progress through the gut?

Proximal gut relatively sterile -> more and more Microbiota

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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

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What is the main nutrient produced by the micro biome?

Vitamin K

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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

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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

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What short Chain fatty acids do gut bacteria produce?

Butyrate
Acetate
Propionate

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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)

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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)

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What is a fecal Microbiota transplant?

Take faeces from healthy donors and then give it to sick individuals

Since faces contain many active microbes

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How can fecal Microbiota transplants be delivered?

nasogastric tube
Upper GI endoscopy
Colonoscopy
Put in caecum

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What disease can Fecal Microbiota transplant be used to treat pretty well?

Clostridium difficile infection

IBD symptoms like Chrons disease

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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

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What are some gram negative bacterial infections of the gut?

Salmonella
Campylobacter
Shigella
Enterotoxigenic ecoli

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what is a gram postitive bacteria infection of the GI tract?

Clostridium difficile

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What condition does salmonella cause?

Gastroenteritis

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What are some symptoms of salmonella infection? (Gastroenteritis)

Nausea
Vomiting
Diarrhoea (mostly non bloody)
Fever
Abdominal cramps

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How is salmonella spread?

Ingesting contaminated food or water

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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

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How is salmonella managed?

Usually self limiting )2-3 days)

Fluid resus with electrolytes

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How is campylobacter normally spread?

Fecal-oral route usually from poultry

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What are the symptoms of campylobacter causing gastroenteritis?

Fever
Abdominal cramps
Diarrhoea (produces cholera like cytotoxin)

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How iis campylobacter managed?

Normally self limiting

Fluid/electrolyte replacemtn

Abx if diarrhoea bloody

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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

What is HUS?

Haemolytic Uraemic Syndrome

What is Haemolytic Uraemic Syndrome (HUS)?

Triad of: -anaemia -thrombocytopenia -acute kidney injury

Which 2 gram negative rods can cause HUS?

Shigella Campylobacter

Why are antibiotics carfully given with ram negative Rod infection?

Trying tp avoid resistance

What is the relative duration of the gram negative rod infections causing gastroenteritis?

Enterotoxigenic e-coli (days) Salmonella (days) Shigella (weeks) Campylobacter (weeks)

Which of the gram negative rods that can cause gastroenteritis which one is likely to produce symptoms that last for weeks?

Campylobacter

Which one of the gram negative rods can cause bloody diarrhoea?

Shigella Campylobacter

What type of organism is Clostridium difficile?

Gram positive Anaerobic Bacillus Forms spores

How is Clostridium difficile spread?

Faecal oral route Minor component of normal Microbiota

What is usually the main cause of C.difficle infection?

Following antibiotic treatment

What are the 2 types of toxins produced by C.difficle?

Toxins A and B

What type of toxin is Toxin A and Toxin B produced by Clostridium difficile?

A = enterotoxins (excessive secretion and inflammation) B = cytotoxin (kills coloncytes)

What are the symtoms of C.difficle infection?

Asymptomatic Varying degrees of diarrhoea Abdominal cramping Sometimes: Pseudomemrabnous colitis Toxic megacolon

How is toxic megacolon treated?

Surgery

What is pseudomembranous colitis?

Inflammatory condition Where elevated yellow plaques found in the colon

How is Clostridium difficile infection treated?

Remove offending abx Fluid resus Metronidazole/vancomycin Probiotics

What are the best abx to treat C.diff?

Vancomycin Metronidazole

What is the major precipating factor in gastroenteritis caused by c.diff?

Abx

In rare cases what can C.difficle infection lead to?

Toxic megacolon

What are some viral causes of gastroenteritis?

Rota virus Norovirus

What are some parastitic causes of gastroenteritis?

Cryptosporidium Giardia Entamoeba

What age group does rota virusgastroenteritis affect?

Under 5s (Only needs a small dose)

What are the symptoms of rota virus causing gastroenteritis?

Vomiting Fever Diarrhoea

How does rota virus cause diarrhoea?

Increased chloride secretion Disrupts SGLT1 (malabsorption) Reduced brush border enzyme function

How is rota virus gastroenteritiiis treated?

Fluid replacemtn

How does rota virus affect chloride secretion?

CFTR channels open Chloride secreted Na+ follows Cl- Water follows in gut lumen = diarrhoea

How does SGLT1 disruption cause problems with roots virus gastroenteritis?

Inc diarrhoea Reduced movemtn of Na/Glucose into enterocyte Higher osmotic load in gut Water moves by osmosis

How can we differentiate norovirus to rota virus?

Norovirus can affect any age so cant develop an immunity to it like rota virus

How like does a norovirus infection last?

Usually like 3 day

What part of the gut does norovirus affect?

Small intestine

What symptoms occur with norovirus causing gastroenteritis?

Watery diarrhoea Vomiting Fever

What causes the watery diarrhoea with norovirus infection?

Anion secretion into gut lumen leading to water moving into lumen

What causes vomiting in norovirus gastroenteritis?

Delayed gastric emptying

How is norovirus gastroenteritis treated?

Oral rehydration therapy

What are the parasitic causes of gastroenteritis?

Cryptosporidium Giardia lamblia Entamoeba histolytica

What is the difference between the 3 parasitic causes of gastroenteritis?

Cryptosporidium = sporozoan so non motile Giardia lamblia = motile due to flagella Entamoeba = motile due to amoeba (cytoplasmic projections)

How is cryptosporidium transmitted?

Facial oral route but can survive in bodies of water

Who are normally affected by cryptosporidium?

People in poorly sanitised pools Parents of infected children People handling infected cattle Backpackers and hikers drinking infected water

What is an oocyst?

Cyst containing the parasite which we ingest into the body

Where does the oocyst reproduce once it’s in the body?

Epithelial cells at distal small intestine and then excreted in faces

What are the symptoms of cryptosporidium gastroenteritis?

Watery diarrhoea Malabsorption Chloride secretion

How is cryptosporidium gastroenteritis managed?

Supportive (fluids) Anti parasitics (vulnerable patients)

How does Giardia present?

Asymptomatic (if symptomatic normally affects children)

How is Giardia spread causing gastroenteritis?

Fecal oral route (contaminated water)

What is the rough incubation period leading to symptoms in Giardia?

10+ days

What are some symptoms of Giardia infection?

Diarrhoea (which can be persistent) Abdominal cramping

What is the 2 stage lifecycle of Giardia?

Cyst ingested: Stomach acid and pancreatic enymes relase parasite from cyst leading to it multiplying in the small intestine damaging the proximal small intestine Parasite then goes back into the cyst stage in the colon to be excreted

How is Giardia gastroenteritis treated?

Antibiotics Fluid rehydration therapy

What deficieny can occur post Giardia infection?

Lactase deficiency

How does entamoeba histolytica infection present?

Most asymptomatic If symptomatic: Diarrhoea Liver abcesses (rare)

How is entamoeba histolytica transmitted?

Faecal oral (from contaminated food or water)

Who does entamoeba histolytica normally affect?

Travel to tropical places that have poor sanitary conditions Living in poor sanitary conditions Male intercourse

What is the life cycle of entamoeba histolytica?

Cysts ingested Protozoa exit cyst in colon (excystation) where the active trophozoites invade the mucosa Can infect the liver too and then the heart’ Trophozoites enter back into cysts to be passed out as faeces

Are entamoeba histolytica that are passed out in thee cyst form considered infective? Are entamoeba histolytica that are passed out in thee trophozoite form considered infective?

Cyst form = infective (what we ingest Trophozoite form = non infective

What is the treatment for entamoeba histolytica?

Antiprotozoals + metronidazole If they get severe colitis or toxic megacolon surgery needed

What is the most common causative organisms for travellers diarrhoea?

Enterotoxigenic e-coli

What is defined as travellers diarrhoea?

Passing 3 or more loose watery stools With or without fever or abdominal pain

How long does travellers diarrhoea normally affect a patient?

2 weeks If ore unlikely bacteria

Who are antibiotics usually given to if they have travellers diarrhoea?

Vulnerable patients

What are the risks of getting travellers diarrhoea?

Place you visit Diet On PPIs Young (<6 yrs) Blood group O

How can you prevent travellers diarrhoea?

Good. Hand hygiene Food and water precautions

How do you treat travellers diarrhoe? Mild/moderate

Mild/moderate (less than 6stools/24hrs) Hydration (oral with safe water) Antidiarrhoeal agents

How do you treat severe travellers diarrhoea?

More than 6 stools per 24hrs IV fluids Abx if appropriate

GI Infections Flashcards

(105 cards)