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Infectious Diseases > Lecture 1 Infectious Diarrhoea > Flashcards

Lecture 1 Infectious Diarrhoea Flashcards

1
Q

Define Diarrhoea

A

Changes in fluidity and frequency of stool

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2
Q

Define Gastro-enteritis

A

Three or more loose stools/day and accompanying features (abdominal pain, vomiting)

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3
Q

Define Dysentry

A

Large bowel inflammation, bloody stools

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4
Q

Describe the epidemiology of gastro-enteritis

A

Contamination of foodstuffs
Poor storage of produce
Travel-related infections e.g. salmonella
Person to person spread- Norovirus

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5
Q

Name defences against enteric infections

A
  • Hygiene
  • Stomach acidity- antacids (no protection) and infection
  • Normal gut flora- Cl. Difficile diarrhoea
  • Immunity- HIV and Salmonella
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6
Q

Clinical features of non-inflammatory diarrhoeal disease (Cholera)

A

Frequent watery stools with little abdo pain

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7
Q

How does cholera lead to watery stools

A

increases cAMP levels and Cl secretion and loss from cells along with Na and K
Osmotic effect leads to massive loss of water from the gut

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8
Q

Clinical features of inflammatory diarrhoeal disease (Shigella dysentery)

A

Inflammatory toxin damage and mucosal destruction leading to bloody stool

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9
Q

What organism may produce inflammatory and inflammatory clinical features

A

C.difficile

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10
Q

If the symptoms are 2 weeks is it likely to be gastro-enteritis

A

No

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11
Q

How do you assess the patient?

A 
Risk of food poisoning 
Assess hydration
-	Postural BP
-	Skin turgor
-	Pulse

Features of inflammation

  • Fever
  • Raised WCC
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12
Q

What features would you look for in an infant

A
  • Sunken fontanelle
  • Few or no tears
  • Sunken eyes and cheeks
  • Decreased skin turgor
  • Dry mouth or tongue
  • Sunken abdomen
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13
Q

What investigations would you carry out?

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
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14
Q

Differential diagnosis of infectious diarrhoea disease

A
  • Inflammatory bowel disease
  • Spurious diarrhoea- secondary to constipation
  • Carcinoma
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15
Q

What is the incubation time of Campylobacter Gastroenteritis

A

Up to 7 days

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16
Q

What is the post infection sequelae

A

Guillain-Barre syndrome, reactive arthritis

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17
Q

When do symptoms of Salmonella Gastroenteritis appear?

A

<48 hours after exposure

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18
Q

How long does Salmonella Gastroenteritis diarrhoea last

A

Diarrhoea usually lasts <10 days

19
Q

Prolonged carriage of Salmonella Gastroenteritis may be associated with what?

A

Gall stones

20
Q

How does E.coli cause symptoms

A

Produces shiga toxin
E.coli stays in the gut but the toxin gets into the blood
Toxin can cause haemolytic-uremic (HUS) syndrome (haemolytic anaemia and renal failure)

21
Q

What clinical features characterised by

A

Renal failure
Haemolytic anaemia
Thrombocytopenia (toxin stimulates platelet activation)

22
Q

How do you treat an E.coli infection

A

• Treatment supportive, dialysis, transfusion- antibiotics not indicated- can release more toxins into the blood stream

23
Q

When should antibiotics be given when someone has gastroenteritis

A

o Immunocompromised
o Severe sepsis or invasive infection
o Chronic illness e.g. malignancy

24
Q

Describe the routine bacterial culture of gastroenteritis

A
  • Difficult to find pathogen in the midst of complex normal flora
  • Selective and enrichment methods of culture necessary- variety of media and incubation conditions
25
Q

Describe the routine bacterial culture of Campylobacter

A
  • Specialised culture conditions

* C. jejuni/C. coli

26
Q

Describe the routine bacterial culture of Salmonella

A

• 2 species recognised
o Salmonella enterica
o Salmonella bongori

27
Q

Common Salmonella Infections

A
  • Salmonella enteriditis

* Salmonella typhimurium

28
Q

Occasional causes of food poisoning outbreaks

A
  • Staph aureus (toxin)
  • Bacillus cereus (re-fried rice)
  • Clostridium perfringens (toxin)
29
Q

Patients infected with C.difficile usually give a previous history of what

A

The 4C antibiotics

30
Q

What type of toxins do C.difficile produce

A

Enterotoxin (A) and cytotoxin (B) (inflammatory)-

31
Q

How do you treat a C.diff infection

A
  • Metronidazole
  • Oral vancomycin
  • Fidaxomicin
  • Stool transplants
  • Surgery may be required
32
Q

How do you prevent CDI Prevention

A
  • Reduction in broad spectrum antibiotic prescribing
  • Avoid 4 Cs- cephalosporins, co-amoxiclav, clindamycin, ciprofloxacin
  • Antimicrobial Management Team (AMT) and local antibiotic policy
  • Isolate symptomatic patients
  • Wash hands between patients
33
Q

How is CDI managed?

A

• Stop precipitating antibiotic
• Follow published treatment algorithm-oral metronidazole if not severity markers
o Raised temp. >38.5
o WCC >15
o Acute rising creatinine
o Suspicion of colitis/ileus/toxic megacolon
• Oral vancomycin if 2 or more severity markers

34
Q

How are protozoa and helminths infection diagnosed

A

By microscopy

Send stool with request “parasites, cysts and ova please” or P, C and O

35
Q

What are the symptoms of Giardia lamblia infection

A

Abnormal cramps, bloating, nausea and bouts of watery diarrhoea, malabsorption and failure to thrive

36
Q

What are the causes of Giardia lamblia

A

Contaminated water

37
Q

What are the 2 forms of Cryptosporidium parvum (protozoa)

A

Oocysts and Trophozites

38
Q

What are the symptoms of Cryptosporidium parvum infection

A

Watery diarrhoea, nausea and vomiting, abdominal cramps, low grade fever

39
Q

What are the routes of infection for Cryptosporidium parvum infection

A

Ingestion of oocysts in faecally contaminated water

40
Q

What is the most common cause of diarrhoea under 5?

A

Rotavirus

41
Q

What are the symptoms of norovirus

A

Diarrhoea and vomiting

42
Q

Where are the most common places for outbreaks of norovirus

A

Hospitals, community and cruise ships

43
Q

How is norovirus diagnosed

A

PCR test

Infectious Diseases (13 decks)

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