Diarrhoea Notes Flashcards by Cameron Greenhalgh

Give the definition of diarrhoea:

Inc. frequency + fluidity of stools (subjective)

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Give the definition of Gastro-enteritis:

3 or more loose stools a day + accompanying features

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Give definition of dysentery:

Large bowel inflammation –> bloody stools

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What chart is used to look at stools?

Bristol Stool Chart

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How many types does the bristol stool chart have?

Type 1 to Type 7

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Gastro-Enteritis (GE): What are the sources of GE?

food contamination 
Storage of produce 
Travel related infections 
Isolated campylobacter cases 
Person to person spread

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how is contamination of food a source of GE?

Due to increased intensity of farming

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how is storage of food a source of GE?

due to increased bacterial proliferation at room temp

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what is a travel related infection that causes GE?

Salmonella

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what is the name of the person to spread virus that causes GE?

norovirus

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What are some defence mechanisms against Enteric infections?

1) hygiene
2) stomach acidity: inc. susceptible when using PPIs/ antacids
3) Normal flora: when there is dec. flora then there is inc. C.diff
4) Immunity–> HIV –> Salmonella

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What are the 2 types of diarrhoea?

1) Non-inflammatory/ Secretory- Cholera

2) Inflammatory

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Describe Non-inflammatory/ Secretory- Cholera diarrhoea:

Secretory toxin mediated;
Cholera causes inc. cAMP levels + Cl (Chloride) secretion
Enterotoxigenic E.coli
Frequent watery stools with little abdominal pain

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What is the treatment of Non-inflammatory/ Secretory- Cholera diarrhoea?

Rehydration

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Describe inflammatory diarrhoea:

Inflammatory toxin damage + mucosal destruction = Pain + fever
Bacterial infection/ amoebic dysentery
Bloody + mucous diarrhoea

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What is the treatment of inflammatory diarrhoea?

Treatment = rehydration

+ Antibiotics when appropriate

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When assessing a patient with suspected Gastro-enteritis, what are you looking for?

1) Symptoms + duration; longer than 2 weeks–> unlikely to be GE
2) Risk of food poisoning
3) Hydration- how to check: postural BP/ skin turgor/ Pulse
4) Sepsis: Fever/ raised WCC

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What investigations are used in Gastro-enteritis?

1) stool culture
2) blood culture
3) renal function
4) blood count: neutrophilia/ haemolysis
5) abdominal xray- toxic dilatation of colon

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What are the differential diagnosis of someone with Gastro-enteritis?

1) Inflammatory bowel disease
2) Spurious diarrhoea- secondary to constipation
3) Carcinoma
4) Diarrhoea + fever can occur with sepsis outside gut ; lack of abdo pain/ tenderness, no blood/ mucous in stools

What is the general treatment of Gastro-enteritis?

1) Rehydration: IV/ Oral
2) Antimicrobials: Not routinely given
3) Treatment of complications

Name the 3 most common Gastro-enteritis pathogens:

1) Campylobacter Gastroenteritis
2) Salmonella Gastroenteritis
3) E.coli O157

Name some other bacteria that cause Gastro-enteritis:

shigella 
other forms of E.coli 
Staph aureus (toxin) 
Bacillus cereus (re-fried rice)
Clostridium perfringens (toxin)

When do you give antibiotics with Gastro-enteritis?

GE WITH: 
-Immunocompromised
-Severe sepsis/ invasive infection 
-Valvular heart disease 
-Chronic illness/ diabetes 
NOT IN HEALTHY PATIENTS WITH NON-INVASIVE INFECTIONS

The GE pathogen: Campylobacter Gastroenteritis: Describe it:

Up to 7 days’ incubation
Stools negative within 6 weeks
Abdominal pain (can be severe)
<1% invasive
Commonest cause of bacterial food poisoning in UK
Specialised culture conditions
Isolated cases rather than outbreaks

What pathogen is responsible for being the most common cause of bacterial food poisoning in the UK?

campylobacter gastroenteritis

The GE pathogen: Salmonella Gastroenteritis: Describe it:

• Symptom onset <48 hours after exposure • Diarrhoea lasts <10 days • <5% positive blood cultures • 20% patients have positive stools after 20 weeks o Prolonged carriage may be associated with gallstones • Post infectious irritable bowel is common • Screened out as lactose non-fermenters antigen + biochemical tests • Most common – Salmonella enteritidis + typhimurium

The GE pathogen: E.coli O157: Describe it:

• Infection from – Contaminated meat / person to person spread • Typical illness characterised by frequent bloody stools • Produced verocytotoxin that can get into blood (but E.coli itself stays in gut) • Toxin can cause haemolytic-uraemic syndrome (HUS) o Stimulates platelet activation clump and block capillaries o RBCs cannot pass so break down (haemolysis) o Occurs in mesangial cells renal failure + urea

When a patient presents with Clostridium Difficile diarrhoea , what do they usually have a history of?

previous antibiotic treatment | wide spectrum- wipes out normal flora

What are the treatment options for c.difficile diarrhoea?

- metronidazole - oral vancomycin - surgery

What are some preventative measures (prevention) for c.difficile diarrhoea?

* Reduction in prescribing of broad spectrum antibiotics * Antibiotic management team * Isolate symptomatic patients * Wash hands between patients

what is the management of c.difficile diarrhoea?

- stop prescribing antibiotic | - metronidazole/ oral vancomycin

Parasites: Give 2 classes of parasites that can cause disease in humans?

Protozoa + helminths

How are parasitic infections diagnosed?

diagnosed by microscopy

Name 2 UK parasites:

Giardia lamblia & Cryptosporiduium parvum

Describe giardia lamblia:

o Contaminated water o Diarrhoea / malabsorption / failure to thrive o Cysts on stool microscopy o Treatment – Metronidazole

What is the treatment of giardia lamblia?

metronidazole

Describe Cryptosporiduium parvum:

o Contaminated water (animal faeces) o Cysts on microscopy o No treatment

Name an imported parasite:

Entamoeba histolytica

What does Entamoeba histolytica cause?

amoebic dysentery

What is amoebic dysentery?

Amoebic dysentery is an infection of the intestines by a parasite causing diarrhoea that contains blood or mucus. Amoebic dysentery, also called amoebiasis, is caused by a single-celled parasite called Entamoeba histolytica. (from google so probs not important)

Describe Entamoeba histolytica – Amoebic dysentery:

o Vegetative form in symptomatic patient o Cysts in asymptomatic patient o Amoebic liver abscess – long term

What is the treatment for entamoeba histlytica- amoebic dysentery:

metronidazole

What is viral diarrhoea in children under 5 called?

Rotavirus in children under 5

What is viral diarrhoea called in people over 5?

Norovirus

Describe rotavirus:

o Common in winter o Diagnosis by antigen detection o Vaccine available

Describe Norovirus:

o Diagnosis by PCR o Very infectious o Strict infection control measures needed