[22] Gastroenteritis Flashcards
What is gastroenteritis?
The general term used to describe inflammation of the gastrointestinal tract
What is the origin of gastroenteritis?
Usually is infective in origin, although may have non-infective causes
What is the most common cause of gastroenteritis?
Viral
What % of cases of gastroenteritis are viral in developed countries?
30-40%
What can reveal the causative agent in gastroenteritis?
Subtle differences between the length of time between ingestion of food and development of symptoms
How long is there between the ingestion of food and the development of symptoms in bacterial toxins causing gastroenteritis?
Hours
How long is there between the ingestion of food and the development of symptoms in viral gastroenteritis?
Days
How long is there between the ingestion of food and the development of symptoms in bacterial gastroenteritis?
Weeks
How long is there between the ingestion of food and the development of symptoms in parasitic gastroenteritis?
Months
What is diarrhoea?
3 or more loose stools, or stools with increased liquid, per day
What is acute diarrhoea?
Diarrhoea lasting less than 14 days
What is chronic diarrhoea?
Diarrhoea lasting more than 14 days
What is dysentery?
Gastroenteritis characterised by loose stools with blood and mucus
What is travellers’ diarrhoea?
More than 3 loose stools commencing within 24 hours of foreign travel. with or without cramps, nausea, fever, or vomiting
What is the most common cause of travellers’ diarrhoea?
Enterotoxigenic E. Coli
How might travellers’ diarrhoea be prevented?
Patient’s travelling to at risk areas may be required to take prophylactic anti-microbials
What are the risk factors for gastroenteritis?
Poor food preparation, handling, and cooking
Immunosuppression
Poor personal hygiene
What are the symptoms of gastroenteritis?
Cramp-like abdominal pain Diarrhoea with or without blood or mucus Vomiting Pyrexia Night sweats Weight loss
What will be found on examination in gastroenteritis?
The patient may be dehydrated, with possible pyrexia and/or hypovolaemia
What specific features from the history should be elicited to help determine the cause of gastroenteritis?
Bowel movements
Affected family or friends
Recent travel
Recent use of antibiotics within previous 4 weeks
What do you need to know about the bowel movements in gastroenteritis?
Quantity
Character - blood stained, mucus, profusely watery
Why is it important to know if a person presenting with gastroenteritis has had any antibiotics within the previous 4 weeks?
It can suggest a potential C. difficile infection
Why are investigations not necessary for most cases of gastroenteritis?
As the condition is usually self limiting
What investigation may be required in gastroenteritis?
Stool culture
When might a stool culture be required in gastroenteritis?
If there is blood or mucus in stool
If patient is immunocompromised
If severe or persistent
What are the general points of management for any patient with gastroenteritis?
Rehydration
Education to prevent future episodes
Exclusion from work for 48 hours from last episode of vomiting or diarrhoea
How should dehydration be achieved in gastroenteritis?
Encourage oral fluids if possible
If severe dehydration or unable to tolerate oral fluid, consider admitting patient for IV fluid
What needs to be considered when giving the patient IV fluids for rehydration following gastroenteritis?
Need to ensure suitable potassium replacement if severe or persistent vomiting or diarrhoea
Is gastroenteritis a notifiable disease in the UK?
Food poisoning and infectious bloody diarrhoea are
What is meant by food poisoning and infectious bloody diarrhoea being notifiable diseases?
It is the duty of the diagnosing doctor to notify the appropriate body
What organisms causing gastroenteritis are notifiable diseases?
Campylobacter
Salmonella
Who is responsible for notifying Public Health about cases of campylobacter or salmonella?
The laboratory
What are the viral causes of gastroenteritis?
Norovirus
Rotavirus
Adenovirus
What is the most common form of viral gastroenteritis in adults?
Norovirua
What kind of virus is norovirus?
RNA virus
How does norovirus present?
Abdominal cramps
Watery diarrhoea
Vomiting
How long does gastroenteritis caused by norovirus last?
Usually about 1-3 days
What is the most common cause of severe diarrhoea in infants and young children?
Rotavirus
What kind of virus is rotavirus?
A double stranded RNA virus
How long does rotavirus last?
Generally less than a week
What develops from rotavirus infection in childhood?
LIfelong immunity
Where is adenovirus a common cause of diarrhoea?
In children
What are the bacterial causes of gastroenteritis?
Campylobacter
E. Coli
Salmonella
Shigella
What is the most common cause of food poisoning?
Campylobacter
What kind of bacteria is campylobacter?
A gram negative bacillus
What does campylobacter infection typically result from?
Ingestion of chicken, eggs, or milk
What symptoms are caused by campylobacter?
May be a prodrome of fatigue, fever, and myalgia, followed by nausea, abdominal cramps, and diarrhoea
How is gastroenteritis caused by campylobacter treated?
If severe, treat with IV erythromycin
What kind of bacteria is E. Coli?
Gram -ve
How is E. Coli transmitted?
Typically through contaminated foodstuffs
Can also be from infected animals and from person-to-person
Which type of E. Coli is the most common form of travellers diarrhoea?
Enterohaemorrhaigc E. Coli (EHEC)
What kind of bacteria is salmonellla?
A gram negative flagellated bacillus
What are the two serotypes of salmonella most commonly associated with gastroenteritis?
S. typhimurium
S. enteriditis
How is salmonella transmitted?
Through undercooked poultry or raw eggs
What are the symptoms of gastroenteritis caused by salmonella?
Fever Nausea Vomiting Abdominal pain Cramps Bloody diarrhoea
How is gastroenteritis caused by salmonella managed?
Management is generally conservative
How long does gastroenteritis caused by salmonella generally last?
<7 days
What kind of bacteria is shigella?
Gram -ve bacillus
What is the most common serotype of shigella?
S sonnei
How is shigella acquired?
From contaminated dairy products and water
How does gastroenteritis caused by shigella present?
Fever
Abdominal pain
Rectal pain
Bloody diarrhoea
How is gastroenteritis caused by shigella managed?
Management is usually conservative
What complications can campylobacter infections lead to?
Reactive arthritis
Guillan Barre syndrome
Haemolytic uraemic syndrome
Thrombotic thrombocytopaenic purpura
What complications can EHEC cause?
Haemorrhagic uraemic syndrome
What do toxins from bacteria often cause?
An acute onset of diarrhoea and vomiting
How long do symptoms tend to last in gastroenteritis caused by bacterial toxins?
Less than 24 hours
What bacteria produce toxins that can cause gastroenteritis?
Staphylococcus aureus
Bacillus cereus
Clostridium perfringens
Vibrio cholera
Where are staphylococcus aureus toxins typically found?
In cooked meat and cream products
Does reheating cooked food destroy the staphylococcus aureus exotoxin?
No, even if the bacteria are destroyed
How are toxins from bacillus cereus typically acquired?
Through reheating cooked rice
What do the toxins from bacillus cereus cause?
Rapid onset nausea and vomiting
How are clostridium perfringes toxins typically acquired?
From reheating cookd meat dishes
What symptoms are caused by the toxins from clostridium perfringes?
Causes diarrhoea, but vomiting is unusual
How are toxins from vibrio cholera obtained?
Typically from contaminated water supplies
What symptoms do the toxins from vibrio cholerae typically cause?
Profound watery diarrhoea, often described as rice water, yet painless in nature
How can gastroenteritis caused by toxins from vibrio cholera be avoided?
An oral vaccine is available
When are parasites a much more likely causative organism in gastroenteritis
In any patient with Travellers’ diarrhoea
What parasites can cause gastroenteritis?
Cryptosporidium
Entamoeba histolytica
Giardia intestinalis
Schistosoma
What kind of parasite is cryptosporidium?
A protozoa
What can cryptosporidium cause in most patients?
A self-limiting watery diarrhoea with abdominal cramps
What can cryptosporidium cause in immunocompromised patients?
Life threatening infections
What does the diagnosis of cryptosporidium involve?
Stool culture for ova, cysts, and parasites
What is the organism Entamoeba Histolytica responsible for?
Amoebiasis
How is entamoeba histolytica acquired?
From the ingestion of food/water contaminated with faeces
How does ameobiasis present?
Bloody diarrhoea
Abdominal pain
Fever
How does an amoebic liver abscess present?
RUQ pain
Swinging pyrexia
Hepatomegaly
What is required for the diagnosis of amoebiasis?
Stool culture for ova, cysts, and parasites
What is the recommended treatment for amoebiasis?
Metronidazole or tinidazole
What is the giardia intestinalis organism responsible for?
Giardiasis
How is giardia intestinalis transmitted?
Through direct contact, or faecal-oral route
What can giardia intestinal cause?
Acute disease or chronic disease
What are the symptoms of acute giardiasis?
Explosive diarrhoea Fever Fatigue Nausea Bloating
What are the symptoms of chronic giardiasis?
Steatorrhoea
Malabsorption
Weight loss
What might stool culture for ova, cysts, and parasites show in giardiasis?
Trophozoites
How do trophozoites appear on microscopy?
‘Tear drop’ shaped
What might be shown on duodenal biopsy in giardiasis?
Villous atrophy
How is giardiasis managed?
Usually metronidazole or tinidazole
What does the organism schistosoma cause?
Schistosomiasis
How is schistosoma acquired?
Contaminated water
How long after infection does acute schistosomiasis present?
About a month
How does acute schistosomiasis present?
Fever Malaise Abdominal pain Bloody diarrhoea Hepatosplenomegaly
What can the hepatosplenomegaly in acute schistosomiasis develop into?
Chronic liver disease and portal hypertension
What may be found on FBC in schistosomiasis?
Eosinophilia
What is required for the diagnosis of schistosomiasis?
Stool culture for ova, cysts, and parasites
How is schistosomiasis treated?
Praziquantel
What are the major species for hospital acquired gastroenteritis?
C. difficile
What kind of bacteria is C. difficile?
A gram +ve organism
When does C. difficile typically develop?
After treatment with broad-spectrum antibiotics, particularly cephalosporins
Why does C. difficile develop after treatment with broad-spectrum antibiotics?
They disrupt the normal microbiota of the bowel
What toxins are produced by C. difficile?
Exotoxins A and B
What do exotoxins A and B cause?
An inflammatory response in the bowel, that results in an inflammatory exudate on the colonic mucosa with intervening areas of normal mucosa
What does the inflammatory response cause by exotoxins A and B culminate in?
Severe bloody diarrhoea
What does the bloody diarrhoea in C. difficile have the potential to develop into?
Toxic megacolon
What is toxic megacolon?
A severely dilated bowel with a high risk of perforation
What does investigation of C. difficile require?
Stool culture specificially including the C. difficile toxin
What may the results of C. difficile stool culture show?
The presence of the bacteria, but absence of toxin
What should be done if the stool culture results show the presence of C. difficile bacteria, but not the toxin?
The results should be interpreted relative to the clinical picture
How is C. difficile treated?
IV fluid rehydration
Oral metronidazole
Isolation
When is vancoymycin used in C. difficile?
In severe disease, or if no improvement seen after 72 hours
What are the non-infective causes of gastroenteritis?
Radiation colitis
Inflammatory bowel disease
Microscopic colitis
Chronic ischaemic colitis
What is radiation colitis?
Inflammation of the gastrointestinal tract secondary to radiation therapy
What does microscopic colitis cause?
A chronic watery diarrhoea
Who does microscopic colitis typically affect?
Females
What happens to the colon in microscopic colitis?
It appears normal on endoscopy, however biopsy demonstrates an increase in the number of inflammatory cells
What is chronic ischaemic colitis caused by?
A compromise in blood supply to the colon
Where does chronic ischaemic colitis commonly affect?
The watershed area around the splenic flexure
How is a diagnosis of chronic ischaemic colitis confirmed?
On endoscopy, where one might observe ‘blue swollen mucosa’
