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Infection > Introduction to Infection - Diarrhoea > Flashcards

Introduction to Infection - Diarrhoea Flashcards

1
Q

What is Diarrhoea?

A

An increased fluidity and frequency of stool

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2
Q

What is Gastro-Enteritis?

A

Describes diarrhoea in the setting of other symptoms

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3
Q

What are the features of Gastro-Enteritis?

A
  • 3 or more loose stools/day
  • Pain
  • Blood/mucous in stool
  • nausea and vomiting
  • fever
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4
Q

What is dysentery?

A

An infection/inflammation of the large bowel causing a large degree of bloody diarrhoea, abdo pain, N+V and fever

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5
Q

What are the 2 main types of dysentery?

A
  • Bacillary dysentery - caused by shigella bacteria

- Amoebic dysentery - caused by entamoeba histolytica

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6
Q

What are the main causes of gastro-enteritis?

A
  • Contaminated food; e.g. campylobacter in chicken
  • Poor food storage/hygiene
  • Salmonella in outbreaks and related to travel
  • Person to person spread - especially in norovirus
  • Viruses are most common
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7
Q

What is the impact of diarrhoeal illness on mortality?

A

Tiny in the western world, massive in the developing countries

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8
Q

What are our defences against enteric infections?

A
  • Hygiene
  • Stomach acid (antacids bad)
  • Normal flora (broad abx bad)
  • Immunity (HIV and immunosuppression bad)
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9
Q

What is a common bacterial illness for HIV to present with?

A

Salmonella infection

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10
Q

What are the 3 different types of diarrhoea?

A
  • Non-inflammatory/Secretory (Cholera)
  • Inflammatory (shigella dysentery)
  • Mixed (C. diff)
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11
Q

What happens in secretory diarrhoea?

A

Toxins cause an increased secretion of fluid to cause frequent watery stools with little abdo pain.
Cholera increases cAMP levels and Cl secretion; enterotoxigenic E.coli in travellers’ diarrhoea

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12
Q

What is the mainstay treatment for secretory diarrhoea?

A

Rehydration - mostly ORT

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13
Q

What happens in inflammatory diarrhoea?

A
  • inflammation of the gut mucosa leads to pain and fever

- occurs with bacterial infection and amoebic dysentery

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14
Q

What is the treatment for inflammatory diarrhoea?

A
  • Rehydration alone is often sufficient (ORT)

- May use antimicrobials/abx

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15
Q

What important things do we look for in Hx/Ex of diarrhoeal illness?

A
  • Symptoms/duration - >2/52 then unlikely to be infective
  • Food poisoning - diet, contact, travel
  • Assess hydration - look out for postural hypotension, skin turgor and pulse
  • Look for signs of SIRS - fever and raised WCC
  • Watch electrolytes
  • Children may also see sunken fontanelles, eyes, cheeks and abdomen and few tears
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16
Q

What investigations may be useful in diarrhoeal illness?

A
  • Stool culture
  • Blood culture
  • Renal function
  • Blood count - neutrophilia/haemolysis
  • Abdo X-ray - if abdomen is distended and tender be wary of toxic dilatation and the risk of perforation
17
Q

What are some possible differential diagnoses for diarrhoea?

A
  • gastro-enteritis/dysentery
  • IBD
  • Spurious diarrhoea - secondary to constipation
  • Cancer
  • Sepsis outside the gut (UT or pneumonia)
18
Q

What signs might suggest that diarrhoea is a result of sepsis from outside the gut?

A
  • lack of abdominal pain/tenderness or localising symptoms

- no blood/mucous in the stools

19
Q

What are the features of campylobacter gastroenteritis?

A
  • Up to 7 days incubation
  • Stools negative within 6 weeks
  • can be severe abdo pain
  • rarely ever invasive <1%
  • Post infection can develop Guillain-Barré or reactive arthritis
20
Q

What are the main types of campylobacter which we look for?

A

Campylobacter jejuni

Campylobacter coli

The most common cause of bacterial food poisoning in the UK - usually in isolated cases from chicken, contaminated milk, puppies

21
Q

What are the features of salmonella gastroenteritis?

A
  • Symptoms usually onset in under 48h after exposure
  • Diarrhoea usually for <10 days
  • Will rarely have a positive blood culture (<5%) but if it does then suspect HIV
  • Carriage in stool can last up to 20 weeks
  • Can be associated with gall stones and post-infectious IBS
22
Q

What are the particular features of salmonella on culture?

A
  • Lactose non-fermenter

- Antigen/biochemical tests

23
Q

What are the most common salmonella infections in the UK?

A

Salmonella enteritidus

Salmonella typhimurium

From pet reptiles or abroad

(different from S. typhi and S. paratyphi - enteric fever)

24
Q

What is the most common form of E.coli in UK gastroenteritis?

A

E.coli O157

25
Q

How does E.coli O157 spread?

A

Contaminated meat or person-to-person

26
Q

What are the typical features of E.coli O157?

A
  • Frequent, small volume bloody stools
  • Abdominal pain
  • Stays in gut but toxin gets into the blood where it causes HUS
27
Q

What is HUS?

A

Haemolytic Uraemic Syndrome - often in 10 days after E.coli O157 infection.

Renal Failure - Haemolytic Anaemia - Thrombocytopaenia

28
Q

Where is E.coli O157 more common?

A

Rural areas - contaminated water supplies, more livestock etc.

29
Q

What are some other bacteria that we may look for in gastroenteritis?
(Not campylobacter, salmonella or E.coli O157)

A
  • Shigella - highly infectious and easily causes outbreaks
  • E.coli - other forms not looked for routinely including enterotoxic E.coli (traveller’s diarrhoea)
  • Staph aureus
  • Bacillus cereus (reheat)
  • Clostridium perfringens
30
Q

When should you give antibiotics in gastroenteritis?

A 
If...
-
 Immunocompromised
- Severe sepsis
- Valvular heart disease
- Chronic illness
- Diabetes
31
Q

What causes Clostridium difficile diarrhoea?

A

C.diff infection due to broad spectrum antibiotic use

5 C’s; cephalosporins, co-amoxiclav, clindamycin, ciprofloxacin and clarithromycin

32
Q

How do you treat C.diff infection?

A
  • Rehydration
  • Metronidazole in minor
  • Oral vancomycin (not absorbed)
  • Fidaxomicin
  • Stool transplant
  • Colectomy
33
Q

How does C. diff cause diarrhoea?

A

Two toxins:

  • Enterotoxin (secretory)
  • Cytotoxin (inflammatory)
34
Q

What test do you ask for if you suspect parasite cause?

A

Microscopy: Parasites, cysts and ova

35
Q

What are some common UK parasites?

A
  • Giardia lamblia - contaminated water (metronidazole)

- Cryptosporidium - common in AIDS and immunocompromised (no treatment, report)

36
Q

What are some imported parasites?

A

Entamoeba histolytica - amoebic dysentery - liver abscess - treat with metronidazole

37
Q

What are some causes of viral diarrhoea?

A
  • Rotavirus in under 5s
  • Adenoviruses
  • Noroviruses - outbreaks in hospital, community, cruise ships
38
Q

How does norovirus spread?

A

Contact and aerosol spread

Infection (12 decks)

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