Gastroenteritis Flashcards by Don J

What is gastroenteritis?

Inflammation of the GI tract usually considered infective in origin.

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What is important to consider in gastroenteritis?

The subtle differences in the length of time between ingestion of food and development of symptoms.

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How long does it take for the following to present:

Bacterial toxin

Viruses

Bacteria

Parasites

Bacterial toxins = hours

Viruses = days

Bacteria = weeks

Parasites = months

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Definition of diarrhoea

3 or more loose stools or stools with increased liquid per day

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Definition of…

Acute diarrhoea

Chronic diarrhoea

Dysentery

Traveller’s diarrhoea

Acute diarrhoea = Lasting < 14 days

Chronic diarrhoea = > 14 days

Dysentery = Loose stools with blood and mucus.

Travellers’ diarrhoea = More than 3 loose stool commencing within 24 hours of foreign travel, with or without cramps, nausea, fever or vomiting.

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Risk factors

Poor food prep

Immunocompromised

Poor personal hygiene

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Clinical features

Cramp-like abdo pain and diarrhoea +/- blood or mucus.

Can have vomiting, night sweats and weight loss.

Dehydration and potential pyrexia.

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What are important questions to ask about features of history?

Bowel movements (blood-stained, mucus or profusely watery)

Affected family or friends

Recent travel abroad

Recent use of abx (can be C. diff)

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What specific complications may patients present with?

Guillain Barre syndrome

HUS

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Investigations

Usually not necessary as most infections are self-limiting

Stool culture is often warranted especially with blood or mucus in the stool, if the patient is immunocompromised or if severe/persistent.

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General management

Rehydration to encourage oral fluid intake where possible.

If there is severe dehydration or can’t tolerate oral fluid they might need admission for IV fluids.

Education on future episodes

Exclusion from work

In UK both food and infectious bloody diarrhoea are notifiable diseases and it is the duty of the diagnosing doctor to notify the appropriate body.

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What certain organisms are also notifiable on their own?

Campylobacter

Salmonella

This is the duty of laboratory identifying organism to notify Public health body

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Viruses that can cause it

Norovirus

Rotavirus

Adenovirus

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Features of Norovirus

ssRNA that is the most common viral gastroenteritis in adults

Abdo cramps

Watery diarrhoea + vomiting

Usually lasts 1-3 days

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Features of Rotavirus

dsRNA

Causes severe diarrhoea among infants and young children

Generally self-resolves in less than a week

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Features of adenovirus

dsDNA that is a common cause of diarrhoea in children

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Bacteria that can cause gastroenteritis

Campylobacter

E. coli

Salmonella

Shigella

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Features of campylobacter

Most common cause of food poisoning from chicken, eggs or milk.

Prodrome of fatigue, fever or myalgia

Followed by nausea, abdo cramps and diarrhoea.

Complications of campylobacter

Guillain Barre syndrome

HUS

TTP

Features of E. coli

G- bacillus that is typically transmitted through contaminated food.

It can also spread from animals to human or from person to person.

ETEC is the most common cause of Travellers’ diarrhoea

What is E. coli 0157:H7 associated with?

HUS

Do not give abx.

Features of salmonella

G- flagellated bacillus with two common serotypes - S. typhimurium and S. enteritidis.

Transmitted through undercooked poultry or raw eggs

Results in fever, vomiting, abdo cramps and bloody diarrhoea

Features of shigella

G- bacillus

Commonly acquired from contaminated dairy products and water

Presents with fever, abdo pain or bloody diarrhoea.

Toxins from bacteria often cause an acute onset and vomiting.

Symptoms tend to last less than 24h.

Give examples of bacterial toxins

S. aureus toxin

Bacillus cereus

Clostridium perfringes

Vibrio cholera

Features of S. aureus toxin

Typically found in meat or dairy products Even re-heating of the cooked food does not destroy the exotoxin even if the bacteria are destroyed.

Features of bacillus cereus

Found in reheated rice and can cause rapid-onset vomiting and abdominal cramps

Features of clostridium perfringes

Acquired from re-heating meat dishes. Causes diarrhoea yet vomiting is less common.

Features of vibrio cholera.

Acquired most commonly from contaminated water supplies Causes profound watery painless diarrhoea. There is an oral vaccina available for this.

In any patient with Travellers' diarrhoea, parasites are more likely to be the causative organism. Give examples of parasites that can cause gastroenteritis.

Cryptosporidium Entamoeba histolytica Giardia intestinalis Schistosoma

Features of cryptosporidium

Protozoan that causes a self-limiting watery diarrhoea and abdo cramps The diagnosis is made with stool cutlure for ova, cysts and parasites. **This can be life-threatening in immunocompromised patients.**

Features of entamoeba histolytica

Anaerobic amoebozoan that becomes acquired from the ingestion of food or water contaminated with faeces. Presents with bloody diarrhoea, abdo pain and fever Stool culture for ova, cystss and parasites will confirm diagnosis. Treatment with metronidazole or tinidazole.

Features of giardia intestinalis.

Parasite transmitted through direct contact or faeco-oral route Can cause acute disease with diarrhoea, fever, fatigue, nausea and bloating Can also cause chronic disease with steatorrhoea, malabsorption and weight loss. Stool culture for ova, cysts and parasites will confirm diagnosis. Metronidazole or tinidazole is the treatment

Features of schistosoma

Fluke Acquired throught contaminated water. Acute schistosomiasis develops about a month after initial infection and presents with fever, malaise, abdo pain and blood diarrhoea. Severe cases can cause chronic liver disease Eosinophilia can be seen on FBC. Stool culture for ova, cysts and parasites will confirm diagnosis. Treatment is praziquantel

What is the main pathogen of hospital acquired gastroenteritis?

C. diff

Features of C. diff

G+ that can develop following the use of broad spectrum abx due to the disruption of the normal microbiota. This leads to overgrowth of C. diff and production of **exotoxins A & B.**

Explain the consequence of exotoxin A&B

Produce a sizeable immune response from bowel. This leas to inflammatory exudate on the colonic mucosa. This leads to severe bloody diarrhoea and a risk of developing toxic megacolon.

Ix of C. diff

Stool culture and C. diff toxin testing (CDT)

Treatment of C. diff

IV fluid rehydration **Oral metronidazole** or potentially vancomycin if severe disease or no improvement within 72h.

Non-infective causes of gastroenteritis.

Radiation colitis IBD Microscopic colitis Chronic ischaemic colitis

What is microscopic colitis

Colon is macroscopically normal but on biopsy there is an increased number of inflammatory cells present.

Explain chronic ischaemic colotis

Due to compromised blood supply to colon. Most commonly affect the **watershed area** around the splenic flexure. Diagnosis is confirmed on endoscopy with a **blue swollen mucosa**

Important causes of dysentery

Campylobacter Shigella Salmonella Norovirus

What should be considered if the patient has travelled abroad?

Parasites ETEC