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Gastrointestinal > Gastrointestinal Infections > Flashcards

Gastrointestinal Infections Flashcards

1
Q

What defences against toxins does the GI Tract have?

A
  1. Sight, smell and memory.
  2. Saliva (bacteriostatic secretions).
  3. Gastric acid (acidic environment).
  4. Small intestinal secretions (bile).
  5. Colonic mucus.
  6. Anaerobic environment (small bowel and colon).
  7. Gut microbiome.
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2
Q

Where is the gut microbiome found?

A

In the colon, where there are 10^11 bacteria in an anaerobic environment.
The stomach is microaerophilic and is sterile.

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3
Q

What are the benefits of microbiome?

A
  1. Harmful bacteria cannot compete for nutrients.
  2. Microbiome produces antimicrobial substances.
  3. Helps to develop a neonates immune system.
  4. Produces important nutrients like vitamin K.
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4
Q

What do bacteria produce?

A

Produce short chain fatty acid:

  1. Butyrate: energy source for colonocytes, help regulate gut environment.
  2. Acetate: cholesterol metabolism.
  3. Propionate: regulate satiety.
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5
Q

What conditions cause a low diveristy of bacteria?

A
  1. Obesity.

2. Inflammatory Bowel Disease.

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6
Q

What can microbiome composition effect?

A
  1. Chemotherapy.

2. Insulin’s response to food.

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7
Q

What are prebiotics?

A

Essentially food for the microbiota (carbohydrates and fibre).

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8
Q

What is Faecal Microbiota Transplant?

A

A faecal transfer from healthy donors to the sick in order to treat disease.

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9
Q

What is Faecal Microbiota Transplant effective at treating?

A
  1. Pseudomembranous colitis.
  2. Diarrhoea with C.difficile.
  3. Crohn’s disease.
  4. IBD.
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10
Q

How can Faecal Microbiota Transplant be administered?

A
  1. Nasogastric/Duodenal tubes.
  2. Upper GI endoscopy.
  3. Colonoscopy.
  4. Transplant in caecum.
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11
Q

Where do you get faeces from in Faecal Microbiota Transplant?

A

10-25 year olds that haven’t used antibiotics, laxatives and direct pills, don’t have GI diseases, are completely screened.

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12
Q

How do you process faecal microbiota transplant?

A

Fresh stool is transported or stored in an hour after stool in centrifuged, filtered and diluted.

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13
Q

Name 4 examples of gram negative rods that infect the gut.

A
  1. Salmonella.
  2. Campylobacter.
  3. Shigella.
  4. Enterotoxigenic E-coli.
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14
Q

Give an example of a gram positive bacteria that causes gastroenteritis.

A

Clostridium difficile (gram positive ).

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15
Q

What are the symptoms of salmonella gastroenteritis?

A
  1. Nausea,
  2. Vomiting,
  3. Diarrhoea (non-bloody),
  4. Abdominal cramping.
    Self limiting.
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16
Q

How is salmonella spread?

A

Ingesting, food and water contaminated with salmonella bacteria.

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17
Q

How long does it take for salmonella to develop symptoms?

A

48 hours.

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18
Q

What is the pathophysiology of salmonella?

A
  1. Salmonella gains access to enterocytes (endocytosis`).
  2. Salmonella mover to submucosa and encounter macrophages.
  3. Macrophages transfer salmonella to reticuloendothelial system.
  4. Multiple inside cells.
  5. Cause lymphoid hyperplasia.
  6. Re-enter the gut from the liver.
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19
Q

Which part of the GI tract does salmonella effect?

A

The small intestine.

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20
Q

What is the structure of Campylobacter?

A

Spiral (s shaped) organism (gram negative rod).

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21
Q

How is Campylobacter spread?

A

Spread to humans via faeco-oral route.

Need to multiply within host before symptoms appear (food infection not poisoning).

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22
Q

What is the incubation period of Campylobacter?

A

1-7days.

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23
Q

What are the symptoms of Campylobacter gastroenteritis?

A
  1. Fever,
  2. Abdominal cramping,
  3. Diarrhoea (can be bloody).
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24
Q

What is the pathophysiology of Campylobacter?

A

Releases a cytotoxin.

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25
Q

How long can Campylobacter gastroenteritis last?

A

Days to weeks.

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26
Q

How do you treat Campylobacter gastroenteritis?

A
  1. Fluid/electrolyte. replacement.

2. Antibiotics if bloody diarrhoea.

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27
Q

Who commonly is affected by Shigella?

A

Young children.

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28
Q

How is Shigella spread?

A

From infected stools, person to person.

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29
Q

What is the infectious dose of shigella?

A

Only needs a small dose to cause infection (easily spread between family members).

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30
Q

What is the pathophysiology of shigella?

A
  1. Invades the large intestine colonocytes, multiples in cells and invades neighbouring cells.
  2. Kills colonocytes and forms abscesses in the mucosa.
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31
Q

What are the symptoms of shigella gastroenteritis?

A
  1. Bloody diarrhoea, with mucus.

2. Abdominal cramping.

32
Q

How long does it take shigella gastroenteritis to resolve?

A

Within a week.

33
Q

How is Enterotoxigenic E.coli spread?

A

Spread by the faecal oral route by contaminated water.

34
Q

What is the pathophysiology of Enterotoxigenic E.coli?

A
  1. Invades enterocytes, producing enterotoxins.
  2. Cause hyper secretion of chloride ions.
  3. Water leaves the cells into the gut lumen.
35
Q

List the gram negative bacteria that cause gastroenteritis in order of the duration of symptoms?

A
  1. ETEC.
  2. Salmonella.
  3. Shigella.
  4. Campylobacter.
36
Q

What is the structure of the Clostridium Difficile?

A

Gram positive, anaerobic, spore forming bacillus.

37
Q

How is Clostridium Difficile spread?

A

Minor component of the GI tract but can be transferred by the the faecal oral route.
Spores are hard to get rid of.

38
Q

What is the pathophysiology of Clostridium difficile?

A
  1. Toxin A: an enterotoxin that results in excessive secretion.
  2. Toxin B: Cytotoxin.
39
Q

What is the commonest cause of Clostridium Difficile gastroenteritis?

A

From antibiotics which precipitates the proliferation of the bacteria.

40
Q

What are the symptoms of clostridium difficile gastroenteritis?

A

Asymptomatic (in most people).

  1. Varying degrees of diarrhoea (mild-terrible, rarely bloody).
  2. Abdominal cramping.
41
Q

What are the complications of Clostridium difficile?

A
  1. Pseudomembranous colitis.

2. Toxic megacolon.

42
Q

What is Pseudomembranous colitis?

A

A layer of inflammatory cells, causing elevated yellow plaques that joint to form a pseudomembrane.

43
Q

How do you treat Clostridium Difficile?

A
  1. Remove the offending antibiotic.
  2. Fluid resuscitation.
  3. Metronidazole/vancomycin.
  4. Probiotics.
44
Q

What is the structure for Rotavirus?

A

A double stranded RNA virus.

45
Q

How is Rotavirus spread?

A

Faecal oral route.

46
Q

Who is commonly effected by Rotavirus?

A

Children, adults rarely as immunity lasts into adulthood.

47
Q

What are the symptoms of Rotavirus gastroenteritis?

A
  1. Vomiting is the first symptom.

2. Diarrhoea follows.

48
Q

What is the pathophysiology of of Rotavirus?

A
  1. Chloride secretion allows sodium ions to follow and thus creates an osmotic gradient for water to follow, causing diarrhoea.
  2. SGLT1 disruption: reduced movement of sodium/glucose into enterocyte, this creates a higher osmotic load in gut, water moves by osmosis.
  3. Brush border dysfunction leading to general malabsorption and thus creates an osmotic potential.
49
Q

How do you treat Rotavirus?

A

Manage dehydration.

50
Q

What is the structure of Norovirus?

A

RNA virus.

51
Q

Who do Norovirus commonly effect?

A

EVERYONE. There are multiple strains and thus you cannot develop immunity. Virus is resistant to cleansing.

52
Q

What is the incubation type and the symptom duration for Norovirus?

A

1-2 day incubation and 1-3 day symptoms.

53
Q

What are the symptoms of Norovirus gastroenteritis?

A
  1. Vomiting due to delayed gastric emptying.
  2. Watery diarrhoea (anion secretion).
  3. Fever.
54
Q

How do you treat Norovirus?

A

Oral rehydration therapy.

55
Q

What 3 protozoa can infect the intestinal tract?

A
  1. Cryptosporidium: sporozoan.
  2. Giardia Lamblia: flagellate.
  3. Entamoeba: Amoeba.
56
Q

How is Cryptosporidium spread?

A

Transmitted by the faecal-oral route but can also survive and spread via bodies of water (infected by animal faeces).

57
Q

Who commonly gets infected with cryptosporidium?

A
  1. People who swim in contaminated water.
  2. Child-care workers.
  3. Parents of infected children.
58
Q

What is the Pathophysiology of Cryptosporidium in gastroenteritis?

A
  1. Ingestion of cyst.
  2. Reproduces inside the epithelial cell of the distal small intestine.
  3. Oocytes are excreted in faeces to continue the cycle.
59
Q

What are the symptoms of Cryptosporidium?

A
  1. Watery diarrhoea that is normally self-limiting due to malabsorption (brush border enzymes are affected and chloride secretion).
60
Q

How do you treat Cryptosporidium?

A

Supportive with fluids.

Occasionally anti-parasitic treatment in at risk group like in the immunosuppressed like in AIDs.

61
Q

Who do Giardia gastroenteritis commonly affect?

A

Usually asymptomatic but usually affect children.

62
Q

How is Giardia spread?

A

Via the faecal-oral route, with water supplies often infected like in developing countries.

63
Q

What are the risk factors for developing Giardia?

A
  1. Swallowing giardia picked up from surfaces.
  2. Swallowing water infected.
  3. Travelling to countries where it is common.
64
Q

What is the incubation period of Giardia?

A

10+ days.

65
Q

What are the symptoms of Giardia?

A
  1. Diarrhoea.
  2. Abdominal cramping.
    The symptoms can last up to 6 weeks and is thus the commonest cause of persistent diarrhoea.
66
Q

What is the life cycle of Giardia?

A
  1. Cyst is ingested.
  2. Stomach acid/pancreatic enzymes release the parasite from the cyst, which multiples in the small intestine for 1-2 weeks.
  3. Damages the proximal small intestine causing symptoms of diarrhoea.
  4. Villous atrophy occurs.
  5. Parasite then goes back into cyst stage in the colon and is excreted to repeat the cycle.
67
Q

How do you treat Giardia gastroenteritis?

A

Antibiotics and fluid rehydration therapy.

Post-Giardia infection can cause temporary lactate. deficiency- lactase intolerance.

68
Q

Where is the highest prevalence of Entamoeba histolytica?

A

Developing counties.

69
Q

What are the symptoms of Entamoeba histolytica?

A

Most are asymptomatic.
If symptomatic:
1. Diarrhoea.
2. Liver abscess (rare).

70
Q

How is Entamoeba Histolytica transmitted?

A

The faecal-oral route, from contaminated food or water.

71
Q

Who is commonly affected by Parasitic Gastroenteritis?

A
  1. People who have travelled to tropical places that have poor sanitary conditions.
  2. People that live in institutions that have poor sanitary conditions.
  3. MSM.
72
Q

What is the pathophysiology of Entamoeba Histolytica gastroenteritis?

A
  1. Infection follows the ingestion of a cyst
  2. Excystation occurs in the colon when trophozoites (feeding phase) invade the mucosa. This causes bloody diarrhoea and inflammatory changes similar to IBD.
  3. Infection can also spread to the liver, where abscesses form.
  4. Cysts then pass out with the faeces to infect others.
73
Q

How do you treat Entamoeba Histolytica?

A
  1. Anti-protozoals/metronidazole.

2. Severe colitis/toxic megacolon, that may require surgery.

74
Q

What is Travellers Diarrhoea?

A

Diarrhoea due to the direct result of travelling, commonly enterotoxin Escherichia coli.
Diarrhoea is defined as 3 or more loosely watery stools, commonly with fever and abdominal pain.
If it lasts longer than 14 days it is unlikely to be a bacterial cause.
Give antibiotics if a vulnerable person as it halves the duration of symptoms.

75
Q

What is a persons risk of getting diarrhoea?

A
  1. Place visited (south and east Asia, Central America, west and North Africa.
  2. Dietary exposure.
  3. Less than 6 years old, PPIs, blood group O.
76
Q

How do you prevent travellers diarrhoea?

A
  1. Good hand hygiene.

2. Food and water precaution.

77
Q

How do you treat Travellers Diarrhoea?

A

Mild/moderate (less than 6 stools/24 hours): hydration, antidiarrhoeal agents.
Severe: (more than 6 stools/24 hours): IV fluids potentially and antibiotics if appropriate.
History is very important.

Gastrointestinal (10 decks)

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