Infectious Diarrhoea Flashcards

1
Q

Define Diarrhoea

A

SUBJECTIVE

A condition in which faeces are discharged from the bowels frequently and in a liquid form.

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2
Q

Define Dysentry

A

OBVIOUS

Infection of the intestines resulting in severe diarrhoea (sometimes with the presence of blood and mucus in the faeces.)

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3
Q

Define Gastroenteritis

A

OBJECTIVE

3+ stools in 24 hours plus at least one of the following:

  • Fever
  • Vomiting
  • Pain
  • Blood / Mucus in Stools
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4
Q

What defense mechanisms do we have against dysentery and gastroenteritis?

A
  • Age
  • Hygiene
  • Gastric Acid
  • Gut Motility
  • Normal Flora
  • Gut Immunity
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5
Q

What are the two main mechanism of diarrhoea?

A
  • Toxin

- Invasion

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6
Q

What are the types of diarrhoea?

A

Non-Inflammatory (cholera)
Inflammatory (shigella)
Mixed picture (C. difficile)

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7
Q

What is non-inflammatory diarrhoea?

A
  • Toxin-Mediated
  • Watery stools, rapid dehydration, relatively little abdominal pain.
  • Rehydration therapy is main treatment
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8
Q

What is inflammatory diarrhoea?

A
  • Bacterial Infection
  • Bloody stools, systematic upset, abdominal pain.
  • Rehydration is main treatment. Antimicrobials may be required.
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9
Q

What two organism contamination are often associated with intensely farmed livestock?

A
  • Campylobacter

- Salmonella

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10
Q

What are the main factors which increase the prevalence of GI infections?

A
  • Farming
  • Storage
  • Transport
  • Poor Sterilisation
  • Manual cross-infection
  • Raw egg consumption
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11
Q

What is the incidence of Salmonella and Campylobacter in the UK?

A

100 / 100,000

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12
Q

What is a “novel” organism?

A

“Any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology” - Basically GMO shit.

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13
Q

List two epidemics centred around novel organisms.

A
  • Listeria Monocytogenes

- E. Coli O157

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14
Q

What would you look for in patient assessment?

A

Symptoms: Duration of diarrhoea. Frequency and “quality” of stool.

Risk Factors: food, occupation, travel, antimicrobials, contacts, institution.

Examination of hydration and SIRS: Pulse. Fever. Skin turgor. Urine flow. Patient appearance. Muscle cramps.

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15
Q

What’s SIRS?

A

Systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body.

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16
Q

What investigations do you do for diarrhoea?

A
  • Stool and Blood Culture
  • Renal function
  • Blood count (haemolysis)
  • Sigmoidoscopy
  • X Ray
  • Serology
17
Q

What are some differentials with a patient presenting with Diarrhoea?

A
  • Diarrhoea as part of response to sepsis.

- Inflammatory bowel disease (If Duration > 2 Weeks)

18
Q

What are treatment options for diarrhoea?

A
  • Rehydration
  • Fasting
  • Antimicrobials
  • Treatment of complications
19
Q

What are the characteristics of Salmonella?

A
  • Symptom onset usually less than 48h after exposure and diarrhoea.
  • <5% of cases have positive blood cultures.
  • Extraintestinal manifestations uncommon, but potentially fatal consensus view on antibiotic treatment.
  • 20% have persistently positive stools at 20 / 52
  • 27% have IBS symptoms at 6 months.
20
Q

What are the characteristics of Campylobacter?

A
  • Most common foodborne pathogen.
  • Incubation up to 7 days.
  • Infection clears within 3 weeks.
  • Severe abdominal pain +/- colitic picture.
  • Rarely invasive (immunocompromised) <1%.
  • Post Infective sequelae
21
Q

What are the characteristics of E.Coli O157:H7?

A
  • Enterohaemmorhagic E.coli
  • Excretion over three weeks after symptoms.
  • Produces SLT (shiga-like toxins)
  • HUS largely a complication in children and elderly.
  • 5 to 9 days between onset of diarrhoea and HUS
22
Q

What pathogen is a model for toxin-mediated diarrhoea?

A

Cholera

  • Antimicrobial Resistance
  • Vaccine
23
Q

What are the characteristics of Shigella?

A
  • Largely a disease of childhood / travel.
  • HUS and seizures may complicate.
  • Widespread quinolone use against shigellosis in developing world leading to resistance.
  • Different serotypes hamper the development of a universal vaccine.
24
Q

What is traveller’s diarrhoea?

A
  • About 1/3 travellers develop a bout of diarrhoea.
  • Usually lasts less than 1 week, but persistent diarrhoea in 1-3%
  • Significant shortening by antibiotics.
  • 80% of tourist infections are caused by E.Coli, Campylobacter and Shigella.
25
Q

What is viral gastro-enteritis?

A
  • Rotavirus is the most common viral enteropath
  • More than 800,000 deaths in children under 5 years of age.
  • Faecal Oral transmission
  • Infects mature enterocytes of villous body and tip, with cell deaths and lactose intolerance.
26
Q

What are the 3 main intestinal parasites do they want you to know?

A
  • Cryptosporidiosis
  • Giardia
  • Entamoeba histolytica
27
Q

Characteristics of cryptosporidiosis?

A
  • Water-borne outbreaks.
  • Cattle is the principal reservoir.
  • Self-limiting (but often protracted illness in non-compromised patients).
28
Q

Characteristics of Giardia?

A
  • Present in surface water.
  • Asymptomatic cyst carriers.
  • Treatment: Metronidazole & Tinidazole.
29
Q

Characteristics of Entamoeba histolytica?

A
  • May mimic ulcerative collitis.

- Treat symptomatic disease with 10/7 metronidazole and furamide for cyst carriage.

30
Q

Characteristics of antibiotic associated diarrhoea?

A
  • Can range from mild diarrhoea to severe colitis.
  • 5% to 10% of patients given antimicrobials develop diarrhoea.
  • Usually the overgrowth of C.diff and production of toxins A and B (enterotoxin and cytotoxin)
31
Q

What % of antibiotic associated diarrhoea is caused by Clostridium difficile?

A

10-15%

  • 7% of patients carry c.diff on admittance, and 28% leave with it.
32
Q

How do you test for c.diff infection?

A
  • Sigmoidoscopy (underrated)
  • Stool culture and toxin detection (33% false negative though).
  • PMC can occur with negative toxin tests.
33
Q

How do you treat c.diff?

A
  • Metronidazole
  • Vancomycin
  • Teicoplanin
  • Prevention with biotherapy.
34
Q

What are the steps to haemolytic-uraemic syndrome?

A

Toxin binds to globotriaosylceramide

Platelet activation stimulated

Micro-angiopathy results

attachment to endothelial, glomerular tubule and mesangial cells.

35
Q

What is Norovirus?

A

Commonest cause for viral diarrhoea.

36
Q

How do you diagnose and deal with Norovirus?

A

Diagnosis via PCR
Very infectious
Ward closures common - Staff and other patients are affected/
Strict infection control measures are needed.