GI: Diarrhoea Flashcards

1
Q

Define diarrhoea

A

> 3 loose or watery stool per day

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2
Q

Define acute diarrhoea

A

< 14 days

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3
Q

Define chronic diarrhoea

A

> 14 days

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4
Q

Give some causes of acute diarrhoea

A

1) gastroenteritis

2) diverticulitis

3) Abx therapy

4) constipation causing overflow

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5
Q

How does diverticulitis present?

A

Classically causes left lower quadrant pain, diarrhoea and fever.

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6
Q

Causes of chronic diarrhoea?

A

1) IBS
2) Crohn’s
3) UC
4) Colorectal cancer
5) Coeliac disease

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7
Q

Is tenesmus more common in UC or Crohn’s?

A

UC

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8
Q

What is tenesmus?

A

Tenesmus is the feeling that you need to pass stools, even though your bowels are already empty.

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9
Q

What is C. diff?

A

Clostridium difficile is a Gram positive rod often encountered in hospital practice.

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10
Q

When does C. diff develop?

A

Clostridium difficile develops when the normal gut flora are suppressed by broad-spectrum antibiotics.

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11
Q

What is the 1ary cause of C. diff diarrhoea?

A

It may colonise the intestines without causing any symptoms or issues.

When antibiotics interrupt the normal intestinal microbiome, C. difficile can proliferate and get out of control

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12
Q

What are the 5 most commonly implicated Abx in C. diff diarrhoea?

A

Broad spectrum:

1) Cephalosporins
2) Clindamycin
3) Co-amoxiclav
4) Ciprofloxacin (and other fluoroquinolones)
5) Carbapenems (e.g., meropenem)

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13
Q

How is C. diff transmitted?

A

Faecal-oral route, with spores contaminating surfaces, hands, and medical equipment.

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14
Q

What are some risk factors for C. diff diarrhoea?

A
  • advanced age
  • prolonged hospitalization
  • immunosuppression
  • recent gastrointestinal surgery or procedures.

These factors contribute to the disruption of gut microbiota, increased susceptibility to infection, and a higher risk of complications.

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15
Q

Pathophysiology behind C. diff diarrhoea?

A

1) The pathogenicity of C. difficile is primarily attributed to the production of two large exotoxins: toxin A (TcdA) and toxin B (TcdB).

2) Both toxins are cytotoxic and proinflammatory, causing damage to the intestinal epithelium, fluid secretion, and inflammation.

3) C. difficile toxins also stimulate the production of cytokines and chemokines, leading to the recruitment of neutrophils and other immune cells to the site of infection.

4) This immune response exacerbates tissue damage and contributes to the pathogenesis of diarrhoea.

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16
Q

What is C. diff infection associated with?

A

1) repeated use of antibiotics

2) proton-pump inhibitors (e.g., omeprazole)

3) healthcare settings

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17
Q

Presentation of C. diff infection?

A

Colonisation is usually asymptomatic.

Infection presents with diarrhoea, nausea and abdominal pain.

Severe infection with colitis can present with:
- Dehydration
- Systemic symptoms (e.g., fever, tachycardia and hypotension)
- Toxic megacolon

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18
Q

How is a diagnosis of C. diff infection made?

A

By testing stool samples:

1) C. diff antigen: this only shows exposure to the bacteria, rather than current infection

2) C. diff toxin (CDT) detection in stool

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19
Q

What C. diff antigen is specifically tested for?

A

glutamate dehydrogenase

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20
Q

Describe stages of C. diff infection:

a) mild

b) moderate

c) severe

d) life-threatening

A

a) normal WCC

b) raised WCC (<15), typically 3-5 loose stools per day

c) raised WCC (>15), or an acutely raised creatinine (>50% over baseline), or a temp of >38.5 degrees, or evidence of severe colitis(abdominal or radiological signs)

d) hypotension, partial or complete ileus, toxic megacolon, or CT evidence of severe disease

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21
Q

1st line management of C. diff infection?

A

Current antibiotic therapy should be reviewed and antibiotics stopped if possible.

1st line –> oral vancomycin for 10 days

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22
Q

1st, 2nd and 3rd line therapies for C. diff infection?

A

1st: oral vancomycin for 10 days

2nd: oral fidaxomicin

3rd: oral vancomycin +/- IV metronidazole

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23
Q

Recurrence rate of C. diff infection?

A

Recurrent infection occurs in around 20% of patients, increasing to 50% after their second episode

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24
Q

What is medical management of RECURRENT C. diff infection:

a) within 12 weeks of symptom resolution
b) after 12 weeks of symptom resolutio

A

a) oral fidaxomicin
b) oral vancomycin OR fidamoxicin

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25
Q

Medical management of life-threatening C. diff infection?

A

Oral vancomycin AND IV metronidazole.

Specialist advice - surgery may be considered

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26
Q

What monoclonal Ab is sometimes used in the management of C. diff infection?

A

bezlotoxumab: targets C. difficile toxin B

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27
Q

What may be considered in C. diff infection for patients who’ve had 2 or more previous episodes?

A

faecal microbiota transplant

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28
Q

How long do patients with C. diff infection need to be isolated for?

A

Patients need to be isolated until 48 hours after the last episode of diarrhoea

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29
Q

Complications of C. diff infection?

A

1) Pseudomembranous colitis

2) Toxic megacolon

3) Bowel perforation and sepsis

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30
Q

What is pseudomembranous colitis?

A

Characterised by inflammation in the large intestine, with yellow/white plaques that form pseudomembranes on the inner surface of the bowel wall.

It is seen during a colonoscopy and confirmed with biopsies to examine the histology.

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31
Q

Transmission of E. coli

A
  • contaminated food or water
  • person-to-person contact
  • zoonotic transmission.
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32
Q

Where is E. coli found?

A

Escherichia coli is a predominantly commensal bacterium in the human GI tract.

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33
Q

What do outbreaks of E. coli often involve?

A

Contaminated produce, undercooked meat, and unpasteurised dairy products.

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34
Q

Give some strains of E. coli and what diseases they cause

A

Enterotoxigenic E. coli (ETEC): travellers diarrhoea

Enteropathogenic E. coli (EPEC): relevant in paediatric diarrhoea

Enterohaemorrhagic E. coli (EHEC): includes E. coli 0157 that produces Shiga-like toxins

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35
Q

What severe complication can E. coli0157 cause?

A

Hemolytic uremic syndrome (HUS).

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36
Q

Which E. coli pathotype is often liked to outbreaks from contaminated food?

A

Enterohaemorrhagic E. coli (EHEC) e.g. E. coli 0157

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37
Q

How does E. coli 0157 cause haemolytic uraemic syndrome (HUS)?

A

E. coli 0157 produces the Shiga toxin.

This causes abdominal cramps, bloody diarrhoea and vomiting. The Shiga toxin destroys blood cells and leads to haemolytic uraemic syndrome (HUS).

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38
Q

Why should Abx be avoided if E. coli gastroenteritis is considered?

A

The use of antibiotics increases the risk of haemolytic uraemic syndrome

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39
Q

Clinical features of E. coli diarrhoea?

A

1) Acute watery diarrhoea

2) Bloody diarrhoea

3) Fever

4) N&V

5) Malaise & muscle aches

6) Abdo cramps

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40
Q

What type of E. coli is bloody diarrhoea typically seen in?

A

Notably seen in enterohaemorrhagic E. coli (EHEC) and enteroinvasive E. coli (EIEC), described as ‘haemorrhagic colitis.’

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41
Q

How long does E. coli diarrhoea typically last?

A

Most cases resolve within 5–10 days without medical intervention.

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42
Q

What type of E. coli is persistent diarrhoea mainly seen with?

A

Seen mainly with enteroaggregative E. coli (EAEC), lasting for two weeks or more.

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43
Q

Who are the at risk populations for E. coli diarrhoea?

A

1) Children & elderly: More severe and prolonged symptoms, risk of complications like dehydration and malnutrition.

2) Immunocompromised: Atypical presentations and higher risk for complications.

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44
Q

How can haemolytic uraemic syndrome present?

A

Presents with haemolytic anaemia, thrombocytopenia, and acute renal failure post 5–10 days of diarrhoea.

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45
Q

Investigations in E. coli diarrhoea?

A

Stool sample:

1) Stool culture & sensitivity: gold standard for identifying E. coli strains and antibiotic susceptibility.

2) Polymerase chain reaction (PCR)

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46
Q

Other investigation in E. coli diarrhoea?

A

Bloods: Looking for thrombocytopenia, acute kidney injury that may indicate HUS

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47
Q

Management options in E. coli?

A

Mainly supportive:
- Oral Rehydration Solution (ORS) for mild to moderate dehydration.
- Intravenous fluids for severe dehydration or in cases where oral rehydration is not possible.

Abx:
- Generally not recommended unless specifically indicated by culture and sensitivity results.
- Exceptions include severe illness with systemic symptoms, or in cases caused by specific pathotypes such as EIEC.

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48
Q

Complications of E. coli diarrhoea?

A
  • Dehydration
  • Prolonged diarrhoea (can lead to nutritional deficiencies and weight loss)
  • Electrolyte imbalance: often 2ary to dehydration
  • HUS
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49
Q

Gastritis vs enteritis?

A

Acute gastritis is stomach inflammation and presents with epigastric discomfort, nausea and vomiting.

Enteritis is inflammation of the intestines, and presents with abdominal pain and diarrhoea.

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50
Q

What is gastroenteritis?

A

Gastroenteritis is inflammation all the way from the stomach to the intestines and presents with pain, nausea, vomiting and diarrhoea.

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51
Q

What is the most common cause of gastroenteritis in:

a) adults
b) children

A

Viuses are the most common cause.

a) norovirus

b) rotavirus

52
Q

What are the 3 main causes of viral gastroenteritis?

A

1) Rotavirus

2) Norovirus

3) Adenovirus (tends to cause respiratory symptoms)

53
Q

Which virus typically causes gastroenteritis with respiratory symptoms?

A

Adenovirus

54
Q

Presentation of viral gastroenteritis?

A

A self-limiting episode of diarrhoea, nausea and vomiting lasting <14 days.

1) Acute diarrhoea

2) Vomiting

3) Mild fever

4) Abdo pain

55
Q

Risk factors for viral gastroenteritis?

A
  • exposure to contaminated food and water sources
  • close contact with infected individuals
  • poor hygiene
  • immunocompromised
56
Q

What is the most important aspect of treatment of viral gastroenteritis?

A

preventing, or correcting dehydration

57
Q

Is there a rotavirus vaccine?

A

Yes - since 2013, an oral rotavirus vaccine was added as part of the UK national childhood immunisation programme.

This is >85% effective at preventing severe rotavirus infection in the first two years of life.

58
Q

Is there long lasting immunity for:
a) rotavirus
b) norovirus?

A

a) yes
b) no

59
Q

Describe diarrhoea in viral gastroenteritis

A

1) passage of 3 or more stools per day, for a duration of less than 14 days.

2) Watery and non-bloody

60
Q

Should the presence of blood in stools (in acute diarrhoe) raised suspicion of viral gastroenteritis?

A

No - consider an alternative diagnosis, such as Shiga-toxin producing E-coli or Campylobacter infection.

61
Q

Any child under 3 months old with what temperatur should be urgently admitted to hospital?

A

> 38 degrees

62
Q

What fever in gastroenteritis would indicate bacterial over viral?

A

A temperature >39°C in adults or >38°C in children under 3 months old should raise suspicion of bacterial pathology.

I.e. milder fever in viral causes.

63
Q

What may occur before the onset of diarrhoea in viral gastroenteritis?

A

A short viral prodrome: consisting of mild fever and nausea or vomiting.

64
Q

What are some clinical signs of significant dehydration?

A
  • Dry mucous membranes
  • Tachycardia
  • Hypotension
  • A thin, thready pulse
  • Reduced urine output
65
Q

How is the diagnosis of viral gastroenteritis typically made?

A

The diagnosis of viral gastroenteritis is clinical and thus investigations are not usually warranted.

66
Q

Give some indications for a stool sample in gastroenteritis:

A
  • Diarrhoea which is persistent, lasting >14 days
  • Blood or pus in the stool
  • High suspicion of non-viral gastroenteritis
  • Recent history of hospitalisation and antibiotic therapy
  • Recent foreign travel history
67
Q

Differentials for viral gastroenteritis?

A

1) Bacterial gastroenteritis

2) Food poisoning

3) C. diff infection

4) IBD

5) IBS

6) Coeliac disease

7) Hyperthyroidism

68
Q

What is the most common causative organism of bacterial gastroenteritis?

A

Campylobacter jejuni

69
Q

How does bacterial gastroenteritis typically present?

A

High fever and severe diarrhoea, which is commonly bloody.

70
Q

What is campylobacter typically found in?

A

1) Raw or improperly cooked meat (especially poultry)
2) Untreated water
3) Unpasteurised milk

71
Q

Give 6 causes of bacterial gastroenteritis

A

1) Campylobacter

2) E. coli

3) Shigella

4) Salmonella species

5) Yersinia enterocolitica

6) Staph. aureus

72
Q

Does suspicion of bacterial infection warrant stool microscopy and culture?

A

Yes

73
Q

What are the 2 most common organisms causing food poisoning?

A

1) Staph. aureus:

2) Bacillus cereus: from reheated rice

74
Q

What bacteria can cause food poisoning from reheated rice?

A

Bacillus cereus

75
Q

Onest of diarrhoea & vomiting in food poisoning vs viral gastroenteritis?

A

Diarrhoea and vomiting begin much more quickly in food poisoning (with 12 hours of ingestion)

76
Q

Incubation period of Campylobacter?

A

2-5 days

77
Q

How long do symptoms of Campylobacter typically last?

A

3-6 days

78
Q

Symptoms of Campylobacter infection?

A
  • Abdominal cramps
  • Diarrhoea often with blood
  • Vomiting
  • Fever
79
Q

When should Abx be considered in Campylobacter

A

After isolating the organism where patients have severe symptoms or other risk factors, such as HIV or heart failure.

80
Q

1st line Abx in Campylobacter infection?

A

Clarithromycin

(Azithromycin and ciprofloxacin are alternative options)

81
Q

Classical blood test feature of C. diff infection?

A

leukocytosis

82
Q

How is shigella spread?

A

Shigella is spread via faeces, either person-to-person or through contaminated drinking water or food.

83
Q

Incubation period of Shigella?

A

1-2 days

84
Q

Features of shigella infection?

A
  • Bloody diarrhoea
  • Abdo cramps
  • Fever
  • Shigella can produce the Shiga toxin: can cause HUS
85
Q

Treatment of Shigella?

A

Normally supportive.

Treatment of severe cases is with azithromycin or ciprofloxacin.

86
Q

How is salmonella spread?

A

Salmonella is spread by eating raw eggs or poultry or food contaminated with the infected faeces of small animals.

87
Q

Incubation period of salmonella?

A

12 hours to 3 days

88
Q

Symptoms of salmonella?

A

Watery diarrhoea

This may be associated with mucus or blood, abdominal pain and vomiting.

89
Q

Are Abx necessary in salmonella?

A

only in severe cases and are guided by stool culture and sensitivities (e.g., ciprofloxacin).

90
Q

What is bacillus cereus?

A

Bacillus cereus is a gram-positive rod spread through contaminated cooked food.

91
Q

What does bacillus cereus grow on?

A

It grows on food not immediately refrigerated after cooking (e.g., fried rice or cooked pasta left at room temperature).

92
Q

What toxin does bacillus cereus produce?

A

Whilst growing on the food, it produces a toxin called cereulide that causes abdominal cramping and vomiting within 5 hours of ingestion.

93
Q

Does reheating food kill bacillus cereus?

A

Reheating the food can kill the bacteria but does not destroy the cereulide toxin.

94
Q

How long does bacillus cereus typically take to resolve?

A

<24 hours

95
Q

Typical exam patient with bacillus cereus:

A

1) Develops symptoms soon after eating fried rice that has been left at room temperature.

2) They develop symptoms shortly afterwards, then recover within 24 hours.

Examiners like this question because the course is easily distinguished from other causes of gastroenteritis.

96
Q

What is the most common cause of infective endocarditis in IVDU?

A

Staph aureus

97
Q

How may Bacillus cereus be implicated in infective endocarditis?

A

Bacillus cereus can cause infective endocarditis in intravenous drug users (IVDU), where heroin is contaminated.

98
Q

What is Yersinia enterocolitica?

A

a gram-negative bacillus

99
Q

Transmission of Yersinia enterocolitica?

A
  • Pigs are key carriers, and eating raw or undercooked pork can cause infection.
  • Also spread through contact with infected humans, animals or faeces.
100
Q

What is the key carrier of Yersinia enterocolitica?

A

Pigs (eating raw or undercooked pork can cause infection)

101
Q

Who does Yersinia typically affect?

A

Children

102
Q

Presentation of Yersinia?

A
  • Watery or bloody diarrhoea
  • Abdo pain
  • Fever
  • It can last longer than other causes of enteritis, with symptoms lasting 3 weeks or more
103
Q

What can Yersinia sometimes be confused with in older children?

A

Appendicitis:

Older children and adults can present with right-sided abdominal pain due to mesenteric lymphadenitis (inflammation in the intestinal lymph nodes) and fever, which can give the impression of appendicitis.

104
Q

What is Yersinia pestis?

A

Yersinia pestis (a different specie of Yersinia) is spread through rat flea bites and causes plague.

105
Q

How can Staph. aureus cause diarrhoea?

A

Staphylococcus aureus can produce enterotoxins when growing on foods such as eggs, dairy and meat.

It is the enterotoxin causing symptoms rather than the bacteria.

106
Q

What is Giardia lamblia?

A

A type of microscopic parasite that lives in the small intestines of mammals e.g. pets, farmyard animals or humans.

107
Q

How is giardiasis transmitted?

A

Cysts released in faeces of mammals.

The cysts may contaminate food or water. When eaten, they infect a new host (faecal-oral transmission).

108
Q

How is the diagnosis of Giardiasis made?

A

Diagnosis is made by stool testing (NAAT or EIA testing).

109
Q

Treatment of giardiasis?

A

Treatment is with tinidazole or metronidazole.

110
Q

Who should be notified in suspected cases of food poisoning?

A

The UK Health Security Agency (UKHSA)

111
Q

What can help to reduce dehydration in gastroenteritis?

A

Oral rehydration salt solution (e.g., Dioralyte sachets mixed with water): these contain glucose, potassium and sodium.

112
Q

Are antidiarrhoeal and antiemetic drugs used in gastroenteritis?

A

No - can worsen condition

113
Q

Post gastroenteritis complications?

A

Lactose intolerance
Irritable bowel syndrome
Reactive arthritis
Guillain–Barré syndrome
Haemolytic uraemic syndrome

114
Q

What is the 1st line laxative in constipation?

A

bulk-forming laxative first-line, such as ispaghula

115
Q

Complications of constipation?

A

1) overflow diarrhoea
2) acute urinary retention
3) haemorrhoids

116
Q

What is amoebiasis caused by?

A

Entamoeba histolytica (an amoeboid protozoan)

117
Q

How is amoebiasis transmitted?

A

Faecal-oral route

118
Q

Symptoms of amoebiasis?

A

1) dysentry: profuse, bloody diarrhoea

2) liver abscess: usually a single mass in the right lobe (may be multiple):
- RUQ pain
- fever
- systemic symptoms e.g. malaise
- hepatomegaly

3) colonic abscess

119
Q

Management of amoebiasis?

A

Oral metronidazole

120
Q

Which oragnism causes gas gangrene?

A

Clostridium perfringens

121
Q

What organism is typically seen in canned foods and honey?

A

Clotridium botulinum

122
Q

How does gastroenteritis caused by Staph. aureus present?

A

Severe vomiting & short incubation period

123
Q

Features of giardiasis?

A

1) often asymptomatic

2) non-bloody diarrhoea: steatorrhoea

3) bloating, abdominal pain

4) lethargy

5) flatulence

6) weight loss

7) malabsorption and lactose intolerance can occur

124
Q

Management of giardiasis?

A

Metronidazole

125
Q

What Abx are the leading cause of C. difficile?

A

Second and third-generation cephalosporins e.g. Cefaclor

126
Q
A