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GI > Session 9 > Flashcards

Session 9 Flashcards

1
Q

GI defences

A

-Sight, smell, memory
-Saliva- bacteriostatic secretions
-Gastric acid
-SI secretions (bile)
- Colonic mucus
- Anaerobic environment (small bowel, colon)
- Commensal gut bacteria

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2
Q

Proximal gut is what type of environment

A

Sterile

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3
Q

What kind of environment is stomach

A

Microaerophilic environment

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4
Q

What kind of envionrment is colon

A

Anaerobic

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5
Q

Benefits of gut micro biome

A

Harmful bacteria cannot compete for nutrients
Micro biome produces anti microbial substances
Helps to develop newborns immune system
Produces certain nutrients Vit K

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6
Q

Bacteria in colon produce

A

SCFAs- short chain fatty acids

Acetate, propionate, butyrate

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7
Q

What is Butyrate

A

Energy source for colonocytes, helps regulate gut environment

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8
Q

What is Acetate

A

Involved in cholesterol metabolism

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9
Q

What is Propionate

A

Helps regulate satiety

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10
Q

Gut microbiota and health

A

Obesity = less diversity
IBD = less diversity

Affects response to chemotherapy and insulin response to food

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11
Q

Microbiota and diet and medications

A

Good = high fibre diet, probiotics, prebiotics

Bad = sweeteners, gluten free diet, PPIs, antibiotics in meat = obesity

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12
Q

FMT used for

A

Faecal microbiota transplant (FMT)

Pseudomembranous collitis
Crohn’s
C. difficile

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13
Q

Route of administration for FMT

A

NG/duodenal tubes
Upper GI endoscopy
Colonoscopy
Transplant can be put in Caecum

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14
Q

Where do you get faeces from

A

10-25 year olds

Donors do not use antibiotics, laxatives or diet pills in last 3 months, do not have GI disease, screened for inflammatory markers, Hep and HIV

Fresh stool to transplantation or storage within 1 hour- stool is centrifuged, filtered and diluted

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15
Q

Bacterial infections of the gut organisms

A

Gram negative rods-
Salmonella, Campylobacter, Shigella, Enterotoxigenic E-coli

Gram positive- Clostridium difficile (gram positive)

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16
Q

Symptoms and spread of salmonella

A

Nausea, vomiting and diarrhoea (mostly non-bloody), fever, abdo cramps

Self-limiting (2-3 days)

Spread by ingesting contaminated food and water

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17
Q

What happens inside gut in salmonella infection

A
  • Gain access to enterocytes (endocytosis)
  • Move to submucosa where encounter macrophages
  • Macrophages transfer salmonella to reticuloendothelial system where they multiply inside cells
  • Causing lymphoid hyperplasia
  • Re enter gut from the liver
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18
Q

Symptoms and spread of Campylobacter

A

fever, abdo cramping, diarrhoea (can be bloody)

Days to weeks (generally self-limiting)

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

Faeco-oral route

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19
Q

Features of campylobacter

A

-Spiral/S shaped organism
-Microaerophillic mainly (do not ferment carbs)
- Releases cytotoxin (similar to cholera)

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20
Q

Treatment of campylobacter

A

Fluid/electrolyte replacement
Consider antibiotics if bloody diarrhoea

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21
Q

Symptoms and spread of Shigella

A

bloody diarrhoea with mucus and abdominal cramping

Usually resolves in a week

Spread from infected stools, person to person, sometimes flies, only small dose needed

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22
Q

Pathogenesis of Shigella

A

Causes shigellosis which is a dysentery commonly affecting young children

Invades large intestine colonocytes, multiplies in cells and invades neighbouring cells

Kills colonocytes and forms abscesses in the mucosa

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23
Q

Symptoms and spread of Enterotoxigenic E. coli ETEC

A

Travellers diarrhoea

Spread by faecal oral route by contaminated water

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24
Q

Pathogenesis of ETEC

A

Commensal of colon but also can be a pathogen

Adheres to enterocytes (produces enterotoxins), causes hypersecretion of chloride ions, water leaves cells into gut lumen

25
Q

Summary of gram negative rods different types of diarrhoea

A

Diarrhoea

Can be bloody- Shigella!! (Campylobacter)

Watery- ETEC, salmonella

26
Q

Which gram negative rods have potential for HUS

A

Shigella, campylobacter

27
Q

Duration of gram negative rods longest to shortest

A

Campylobacter, shigella = weeks

Salmonella and ETEC = days

28
Q

What is HUS

A

Haemolytic uraemic syndrome

Triad = anaemia, thrombocytopenia, AKI

29
Q

Symptoms of Clostridium difficile

A

Asymptomatic (most people)
Varying degrees of diarrhoea
Abdominal cramping

In a few cases: pseudomembranous colitis, toxic megacolon, surgery needed

30
Q

Pathology of C. difficile

A

Gram positive, anaerobic, spore forming bacillus

Minor component of GI tract

Following antibiotic therapy, can colonise gut and release toxins (toxins A and B)

31
Q

Spread of C. difficile

A

Can be transferred via faecal oral route

Spores are very difficult to get rid of from an environment (Like hospital)

32
Q

What are toxins A and B of clostridium difficile

A

A- enterotoxin that results in excessive secretion and inflammation

B- cytotoxin

33
Q

What can precipitate C. difficile proliferation

A

Antibiotics- especially broad spectrum

34
Q

What is psuedomembranous colitis

A

Inflammatory condition

Elevated yellow plaques join to form a pseudo membrane

35
Q

Treatment of C. difficile infection

A

Remove offending antibiotic
Fluid resuscitation
Metronidazole/Vancomycin
Probiotics

36
Q

Viral and parasitic causes of gastroenteritis

A
37
Q

Features and spread of gastroenteritis caused by Rotavirus

A

very common cause in under 5s, adults rarely affected

Double stranded RNA

Spread by faecal-oral route (small dose required)

38
Q

Symptoms and treatment of viral gastroenteritis rotavirus

A

Vomiting with a fever are first symptoms

Diarrhoea follows- lasting up to a week

Treatment- manage dehydration

39
Q

Pathology of diarrhoea in rotavirus

A

Chloride secretion- creates gradient for the movement of Na into lumen, water moves by osmosis

SGLT1 disruption- reduced movement of Na/glucose into enterocytes, higher osmotic load in gut, water moves by osmosis

Brush border dysfunction- general malabsorption

40
Q

Features and spread of norovirus

A

Most common cause of non bacterial gastroenteritis in the world

Any age as many strains, only needs small dose

Resistant to cleansing

41
Q

Symptoms and treatment of norovirus

A

Incubation is 1-2 days and symptoms lasts 1-3 days

Infects the SI and damages microvilli (brush border enzymes disruption)

Vomiting, water diarrhoea, fever

Oral rehydration therapy

42
Q

Pathology of symptoms in norovirus

A

Watery diarrhoea= anion secretion, so movement of water into gut lumen

Vomiting= vomiting due to delayed gastric emptying

43
Q

Pathology of symptoms of norovirus

A

Vomiting = delayed gastric emptying
Watery diarrhoea = anion secretion, so movement of water into gut lumen

44
Q

Types of parasitic gastroenteritis

A

Protozoa that infect intestinal tract

Cryptosporidium: sporozoan (non motile)
Giardia Lamblia: flagellate (motile)
Entamoeba: amoeba (move by extending cytoplasmic projections)

45
Q

Transmission of Cryptosporidium

A

Faecal-oral route, survive and spread via bodies of water

46
Q

Disease pathology of Cryptosporidium

A

Ingestion of Oocyst- reproduces inside epithelial cells of distal SI, excreted in faeces to continue cycle

47
Q

Symptoms and treatment of cryptosporidium

A

Water diarrhoea that is normally self limiting

Malabsorption (brush border enzymes affected), chloride secretion

Supportive- fluids, anti-parasitic treatment in at risk groups e.g. AIDS

48
Q

Spread of Giardia

A

Faecal-oral route, water supplies often affected in developing countries

49
Q

Symptoms of Giardia

A

Most asymptomatic but symptoms more common in children

10+ day incubation period

Diarrhoea, abdominal cramping, can last up to 6 weeks- common cause of persistent diarrhoea

50
Q

Treatment of Giardia

A

Antibiotics and fluid rehydration therapy

Post Giardia infection, lactase deficiency is common (lactose intolerance)

51
Q

Pathology of Giardia

A

2 stage life cycle

1- Cyst ingested, stomach acid/pancreatic enzymes release parasite from cyst, multiplies in SI
Damages proximal SI causing symptoms, villous atrophy

2- Parasite goes back into cysts stage in colon- excreted to repeat cycle

52
Q

Entamoeba spread

A

Higher prevalence in developing countries

Faecal-oral route (poor sanitary conditions, MSM)

53
Q

Entamoeba symptoms and treatment

A

80% asymptomatic
Diarrhoea (bloody?) or liver abscess (rare)

Anti-protozoals/metronidazole
Severe colitis/toxic megacolon may need surgery

54
Q

Pathology of Entameeba

A

Infection follows ingestion of cysts

Excystation occurs in colon where trophozoites invade mucosa (bloody diarrhoea and inflammatory changes occurs)

Infection can spread to liver (abscesses form)

Cysts then pass out with faeces- infect others

55
Q

What is travellers diarrhoea

A

ETEC is most common cause

Passing 3 or more loose/water stools (+/- fever and abdo pain)

Greater than 14 days of symptoms makes it less likely to be bacterial

56
Q

Treatment of travellers diarrhoea

A

Antibiotics only for vulnerable/immunosuppressed

Halves duration of symptoms 1.5 days on average

57
Q

Risk of getting diarrhoea

A

Places you visit (south and east Asia, Central America, west and North Africa)

Dietary exposure

Less than 6, PPIs, Blood group O

58
Q

Prevention of travels diarrhoea

A

Good hand hygiene, food and water precautions

59
Q

Mild vs moderate travellers diarrhoea treatment

A

Mild/moderate = less than 6 stools in 24 hours: Hydration and anti diarrhoea agents

Severe = more than 6 stools in 24 hours: IV fluids and antibiotics

GI (22 decks)

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