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Year 3 Infection > Infectious diarrhoea part 1 (plus a bit of part 2 by accident) > Flashcards

Infectious diarrhoea part 1 (plus a bit of part 2 by accident) Flashcards

1
Q

What symptoms are hallmark of diarrhoea?

A

Increased fluidity and frequency of stools

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2
Q

Describe the bowel habit seen with gastroenteritis?

A

3 or more loose stools/day

Will have accompanying features/symptoms

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3
Q

Describe the bowel habit seen with dysentery?

A

Quite obvious

Large bowel inflammation with bloody stools

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4
Q

What causes infectious diarrhoea?

A

1) Contamination of foodstuffs
* Intensively farmed chicken and campylobacter
2) Poor storage of produce
* Ie storing food at room temperature causing bacterial proliferation
3) Travel-related infections e.g. Salmonella
4) Person-to-person spread e.g Norovirus

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5
Q

Give an example of a cause of infectious diarrhoea that is spread through person to person contact

A

Norovirus

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6
Q

What causes infectious diarrhoea, viruses or bacteria?

A

Viruses are commonest cause with campylobacter being the commonest bacterial pathogen

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7
Q

What are the most common food-borne pathogens?

(ie the ones that cause food poisoning)

A

Campylobacter is the most common foodborne pathogen

Salmonella is the pathogen that causes the most hospital admissions

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8
Q

What type of meat is most linked to food poisoning?

A

Poultry

(Chiquen and turkey)

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9
Q

What age group is most at risk of getting/dying of infectious diarrhoea?

Where in the world is the mortality rate highest?

A

Children

death rate highest in certain parts of Africa

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10
Q

What strain of E.coli is famously pathogenic?

A

E.coli O157

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11
Q

What are the defences against enteric infections?

A

Hygiene

Stomach acidity

Normal gut flora

Immunity

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12
Q

What are the types and features of non-inflammatory infectious diarrhoea?

A

Examples of non-inflammatory ID causing organisms:

  1. Cholera - (Vibrio cholerae)
  2. E.coli - (travellers diarrhoea)

Frequent, watery stools with little abdominal pain

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13
Q

What is the general approach to treating non-inflammatory infectious diarrhoea?

A

Rehydration therapy

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14
Q

Describe the mechanism of diarrhoea in cholera?

A

Cholera increases cAMP levels inside of epithelial cells

Increased cAMP results in loss of Cl- from cells along with Na+ and K+

Osmotic effect leads to massive water loss into the lumen (ie diarrhoea)

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15
Q

Describe the clinical features of diarrhoeal illness and what causes these features

A

Watery, frequent stools - for aforementioned reason

Inflammatory toxin damage and mucosal destruction causes PAIN and FEVER

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16
Q

How do assess patients with infectious diarrhoea?

A

Symptoms and duration

Risk of food poisoning - travel, diet, contact

Assess hydration - postural BP, skin turgor, pulse

Features of inflammation (SIRS) - fever, raised WCC

17
Q

What features on examination of a neonate may indicate infectious diarrhoea?

A

Fever etc

Decreased skin turgor

Sunken eyes and cheeks

Sunken fontanelle

Dry mouth or tongue

Sunken abdomen

18
Q

What is the effect of diarrhoea on fluid and electrolyte balance?

A

Can cause severe loss of fluid and electrolytes

Which causes Hyponatraemia and Hypokalaemia

19
Q

How much fluid can patients lose with severe diarrhoea?

How much Sodium?

How much Potassium?

A

1 - 7 Litres of fluid containing 80 - 100 mmol Na+

Hypokalaemia due to K loss in stool (40-80mmol/l of K in stools)

20
Q

What investigations are done to assess patients with infectious diarrhoea?

A
  • Stool culture +/- molecular or Ag testing
  • Blood culture
  • Renal function
  • Blood count - neutrophilia, haemolysis (E. Coli O157)
  • Abdominal X-Ray/CT if abdomen distended, tender
21
Q

What are the differential diagnoses for infectious diarrhoea and why?

A

Inflammatory bowel disease

Spurious (overflow) diarrhoea

Carcinoma

Diarrhoea and fever occurring secondary to sepsis outside of the gut

22
Q

What is spurious diarrhoea?

A

Diarrhoea secondary to constipation

Hx of alternating constipation & diarrhoea

Usually in elderly people

23
Q

If a patient presents with severe diarrhoea and fever - how would you differentiate between infectious diarrhoea or sepsis outside of the gut?

A

Lack of abdominal pain/tenderness

  • this goes against Gastroenteritis

No blood/mucus in stool

  • would show lack of inflammation etc of intestinal mucosa
24
Q

How is Gastroenteritis (infectious diarrhoea) treated?

A

Rehydration therapy:

  • Oral rehydration solution - NaCl & glucose solution
  • or IV Saline

Antibiotics sometimes needed for infectious gastroenteritis depending on the organism

25
Q

What features are indicative of campylobacter gastroenteritis?

A

All the normal symptoms + severe abdominal pain

Incubation period of up to 7 days - so dietary history may be unreliable

26
Q

What other conditions can arise after campylobacter gastroenteritis?

A

Guillain-Barre syndrome

Reactive arthritis

27
Q

What two species of Campylobacter cause the most cases of C. gastroenteritis in the UK?

A

C. jejuni (90%)

C. coli (9%)

28
Q

How are campylobacteria transmitted/caught?

A

Chiquens

Milk

Puppies

Commonest cause of bacterial food poisoning in the UK

29
Q

What characterises infection with E.coli O157?

A

Typical illness characterised by frequent bloody stools

30
Q

What is Shiga toxin?

A

It is the toxin produced by E.coli O157 and Shigella spp.

E. coli O157 stays in the gut but Shiga toxin is what gets into the blood

Shiga toxin can cause Haemolytic-uraemic syndrome (HUS)

31
Q

What is haemolytic-uraemic syndrome?

A

Syndrome caused by Shiga toxin - usually following E.coli diarrhoea

Characterised by:

  • Renal failure
  • Haemolytic anaemia
  • Thrombocytopenia

Most common cause of acute renal failure in children

32
Q

What other symptoms would be seen in Haemolytic uraemic syndrome?

A

The symptoms caused by the infection/Shiga toxin in the first place:

  • Bloody diarrhoea
  • Abdo pain
  • Fever
  • Seizures
  • Lethargy
33
Q

What is the treatment route for HUS?

A

Mainly supportive:

IV fluids

blood transfusion

dialysis if required

Antibiotics not indicated

34
Q

What are the less common causes of food poisoning (and all this infectious diarrhoea stuff)

A

Staph aureus - (toxin)

Bacillus cereus - (re-fried rice)

Clostridium perfringens - (undercooked meat/cooked food left out - toxin accumulates in spore formation)

35
Q

When should antibiotics be prescribed for infective gastroenteritis?

A

Indicated in gastroenteritis if:

  • Immunocompromised
  • Severe sepsis or invasive infection
  • Chronic illness - ie malignancy

Not indicated for healthy person with non-invasive infection

36
Q

Clostridium difficile infection is a rarer infection which is potentially serious

What causes it?

How severe can it be?

A

C.diff diarrhoea

Happens following broad spectrum antibiotic treatment (4 C’s - incl clindamycin, cephalosporins)

Ranges from mild diarrhoea to severe colitis - sometimes requiring surgery

37
Q

What toxins do C.diff produce?

A

enterotoxin (A) and cytotoxin (B) (inflammatory)

38
Q

How can Clostridium difficile infection treated?

A

Oral Metronidazole - first line

Oral Vancomycin - if severe/not responding to Metronidazole

Bezlotoxumab - alternative

39
Q
A

Year 3 Infection (13 decks)

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