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- Y6 Gastrointestinal > Gastroenteritis & infectious colitis > Flashcards

Gastroenteritis & infectious colitis Flashcards

1
Q

Define gastroenteritis.

A

Acute inflammation of the GI tract, manifested by nausea, vomiting, diarrhoea and abdominal pain.

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2
Q

What is the epidemiology of gastroenteritis?

A

Common, and often under-reported, a serious cause of morbidity and mortality in the developing world.

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3
Q

What is the aetiology of gastroenteritis?

A

Can be caused by viruses, bacteria, protozoa, or toxins contained in contaminated food or water. Can be caused by inflammatory or non-inflammatory toxins.

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4
Q

List 3 viral causes of gastroenteritis.

A
  • Rotavirus
  • Adenovirus
  • Astrovirus
  • Calcivirus
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5
Q

List 3 bacterial causes of gastroenteritis.

A
  • Campylobacter jejuni
  • E coli (0157)
  • Salmonella
  • Shigella
  • Vibrio cholerae
  • Listeria
  • Yersinia enterocolitica
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6
Q

Name a protozoal cause of gastroenteritis.

A
  • Entamoeba histolytica
  • Cryptosporidium parvum
  • Giardia lamblia
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7
Q

Name 3 toxins that cause gastroenteritis.

A
  • Staphylococcus aureus
  • Clostridium botulinum
  • Clostridium perfringens
  • Bacillus cereus
  • Mushrooms
  • Heavy metals
  • Seafood
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8
Q

What is the difference between the organisms which cause:

a) diarrhoea
b) dysentery

in bacterial gastroenteritis?

A

NB: diarrhoea = loose stools

dysentery = bloody loose stools (CHESS organisms)

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9
Q

In bacterial gastroenteritis with diarrhoea, what clues might you get from the history with regards to the responsible organism?

A
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10
Q

In bacterial gastroenteritis with dysentery, what clues might you get as to the causative organism?

A
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11
Q

What are some non-inflammatory mechanisms of gastroenteritis?

A

Non-inflammatory - e.g. V cholerae, enterotoxigenic E. coli produce enterotoxins that cause enterocytes to secrete water and electrolytes.

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12
Q

Describe an inflammatory mechanism causing gastroenteritis.

A

Inflammatory mechanisms e.g. Shigella, enteroinvasive E. coli release cytotoxins and invade and damage the epithelium, with greater invasion and bacteraemia in the case of Salmonella typhi.

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13
Q

What is the typical presentation of gastroenteritis?

A
  • Sudden onset nausea, vomiting, anorexia
  • Diarrhoea (bloody or watery)
  • Abdominal pain/discomfort,
  • Fever and malaise
  • Enquire about recent travel, antibiotic use and recent food intake (how cooked, source and whether anyone else is ill)

Effect of toxins: botulinum causes paralysis, mushrooms can cause fits, renal or liver failure.

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14
Q

What are the signs of gastroenterits on physical examination?

A
  • Diffuse abdominal tenderness
  • Abdominal distension
  • Bowel sounds are increased

CHECK FOR:

  • Mucous membranes, skin turgor, cap refill for DEHYDRATION
  • HR, BP – for SHOCK
  • Temperature

These indicate severe disease.

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15
Q

What is the typical time of onset of gastroentritis?

A
  • Toxins (early, 1-24 hours)
  • Bacterial/viral/proozoal (12h or later)
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16
Q

What investigations would you do for gastroenteritis?

A

Bedside:

  • Stool sample - MC&S - bacterial pathogens, ova cysts (eggs), parasites
  • Blood - FBC, blood culture (helps identification if bacteraemia present), U&Es (low K in severe D&V)

Imaging:

  • AXR/US - excludes other causes of abdominal pain

Invasive:

  • Sigmoidoscopy - unnecessary unless IBD needs to be excluded
17
Q

What is the management of gastroenteritis?

A
  • Bed rest, fluid and electrolyte replacement with oral rehydration solution (containing glucose and salt)
  • IV rehydration may be necessary in those with severe vomiting
  • Most infections are self limiting
  • Antibiotic treatment only warranted if severe or the infective agent has been identified e.g. ciprofloxacin against Salmonella, Shigella, Campylobacter

Other:

  • Botulism - botulinum antitoxin IM and manage in ITU
  • PUBLIC HEALTH - often notifiable disease.
  • Educate on basic hygiene and cooking
18
Q

What are the complications of gastroenteritis?

A
  • Dehydration
  • Electrolyte imbalance
  • Prerenal failure
  • Secondary lactose intolerance - particularly in infants
  • Sepsis and shock (particularly Salmonella and Shigella)
  • Haemolytic uraemic syndrome - associated with toxins from E coli 0157
  • Guillain-Barre syndrome may occur weeks after recovery from Campylobacter gastroenteritis
  • Botulism –> respiratory muscle weakness/paralysis
19
Q

What is the prognosis in gastroenteritis?

A

Generally good

Majority of cases are self-limiting

20
Q

Which organism causes rice water diarrhoe?

A

Vibrio cholera

21
Q

Difference between causes of gastroenteritis with salmonella vs campylobacter?

A

Salmonella - from uncooked eggs

Campylobacter - uncooked poultry/raw meat

22
Q

Common cause of diarrhoea associated with antibiotic use?

A

C diff

23
Q

Which of these features do not suggest gstroenteritis?

  1. Streak of blood in vomiting
  2. Large amount of blood in vomit
  3. Intermittent abdominal pain
  4. Constant, worsening/severe abdominal pain
  5. Blood in stool
  6. Mucus in stool
A

2 and 4

24
Q

What is the management of C difficile?

A

Non-severe C difficile:

  1. Metronidazole 400mg PO TDS 10-14days
  2. If no response in 72hrs change to: Vancomycin 125mg PO QDS 10-14days

Severe C difficile:

  1. Vancomycin 125mg PO QDS 14 days + consider adding metronidazole 500mg IV TDS
  2. Specialist advice

If colonic dilatation present:

  1. Vancomycin 125-250mg PO QDS + metronidazole 500mg IV TDS 14 days

If ileus/vomiting:

  1. Consider intracolonic vancomycin
    * Fidaxomycin is a new drug associated with fewer relapses so may be increasingly used*

Recurrence in:

<12 weeks = oral fidaxomicin

>12 = oral vanc or fidaxomicin

Other:

  • bezlotuxumab
  • faecal microbiota transplant
25
Q

What is the MOA of bezlotoxumab?

A

mAb against toxin B in C diff

26
Q

What is the MOA of fidaxomicin?

A

Inhibiting bacterial RNA polymerase at transcription initiation

27
Q

How is C diff colitis diagnosed?

A

TOXIN detection in stool

NB: antigen positivity only shows exposure to C difficile rather than current infection

28
Q

How is C diff severity categorised?

A

Imperial C. difficile guidelines

  • T>38.5ºC
  • HR>90
  • WCC>15
  • Rising Creatinine
  • Clinical or radiological signs of severe colitis
  • Failure to respond to therapy at 72h

Severe = 1 or more of the following –> early surgical and gastroenterology review

DIARRHOEA is not part of the criteria

29
Q

Other than antibiotics what can increase risk of C difficile?

A

PPIs

Abx:

  • Antibiotics use
  • 65+ years (many children colonised but do not get problems)
  • Duration of hospital stay (after 4 weeks, half of patients become positive)
  • Severe underlying diseases
  • Almost always associated with a recent history of antibiotic use (clindamycin, cephalosporin, ciprofloxacin)
30
Q

What 3 antibiotics are the biggest risk factors for C diff?

A

cephalosporins, ciprofloxacin and clindamycin

31
Q

Why is diarrhoea not part of the criteria of C diff severity?

A

You can get ileus and toxic megacolon in very severe disease

32
Q

What is the pathophysiology of C diff?

A

Epithelial cells are damaged by the cytotoxin

Disrupts tight junctions

Causing pseudomembranous colitis with fibrous plaques

33
Q

What are some measures for prevention of C diff infections?

A
  • Hand hygiene with soap and water
  • Isolation
  • Use of PPE
  • Enhanced environmental cleaning (with chlorine)
  • Only use narrow-spectrum where possible
34
Q

What are faecal cultures routinely tested for?

A
  • Salmonella
  • Shigella
  • E. coli O157
  • Campylobacter
  • C. difficile toxin – only tested for in those <65 years, need to ask otherwise
35
Q

How transmissible is C diff?

A

1g faeces = 1 billion spores so very transmissible

- Y6 Gastrointestinal (70 decks)

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