INFECTIONS AND ENTEROCOLITIS Flashcards
What is the most commonly accepted definition of diarrhoea?
> 3 loose stools in 24 hours
What is osmotic diarrhoea?
This occurs when a soluble compound cannot be absorbed by the small intestine, and thus draws fluid into the intestinal lumen.
Examples include: osmotic laxatives; magnesium-based antacids; and foods containing mannitol, sorbitol, or xylitol. Osmotic diarrhoea can also be due to generalised malabsorption (for example, coeliac disease and pancreatic insufficiency).
The volume of diarrhoea is reduced by the absorption of fluid by ileum/colon so the diarrhoea stops when the pt stops eating or the malabsorption substance is discontinued
What is secretory diarrhoea?
results from increased secretion of fluid and electrolytes into the intestine alongside decreased absorption
Can be caused by infections, fatty acids, bile salts and some drugs
Even if the person fasts, secretory diarrhoea will persist
What is inflammatory diarrhoea?
Damage to intestinal mucosal cells affects absorption of fluid and electrolytes and results in fluid and blood loss. Infection (e.g. Shigella) and conditions such as ulcerative colitis and Crohn’s disease are causes of inflammatory diarrhoea.
Nocturnal symptoms are often present.
Outline how increased intestinal motility can cause diarrhoea?
This may present with an increased frequency of stool passage without an increase in volume. It can occur with endocrine conditions such as diabetes and hyperthyroidism.
What are the possible mechanisms that can cause diarrhoea?
Increased osmotic load in the gut lumen
Increase in secretion
Inflammation of intestinal lining
Increased intestinal motility
Whats acute and chronic diarrhoea?
Acute lasts <14 days
Persistant lasts >2 weeks but <4 weeks
Chronic lasts >4 weeks
What typically causes acute diarrhoea?
Infections
What are some common infectious causes of diarrhoea?
Viral - norovirus or rotavirus
E.coli food poisoning
Food poisoning from salmonella, campylobacter or staphylococcus bacteria
C.diff infections
Contaminated food or water - typically giardia or entamoeba histolytica
What are the clinical features of infectious diarrhoea?
Fever
Abdominal pain
Vomiting
Acute diarrhoea
(Dehydration my occur especially in very young or elderly patients)
What are the key investigations for infectious diarrhoea?
Stool microscopy culture sensitivities
Samples for c.diff toxin in some cases
Stool for ova, cysts and parasites in some cases
In which people with infectious diarrhoea should you test stool sample for c.diff toxins?
Elderly
Nursing home residents
Recent antibiotic use
In which people with infectious diarrhoea should you test stool sample for ova, cysts and parasites?
Persistent diarrhoea
Men who have sex with men
Immunocompromised patients
Recent travel abroad
If suspecting giardiasis, amoebas is or cryptosporidium
How is acute diarrhoea managed?
Volume depletion with oral rehydration solutions or in serious cases IV fluid resuscitation
In some cases antibiotic treatment may be indicated
When is antibiotic treatment indicated for acute diarrhoea?
Severe/prolonged sympotms e.g. >5 days
Systemic signs of infection
Extremes of age
Immunocompromised individuals
Complications
Bloody or mucoid stools
What are the causes of chronic diarrhoea?
IBS
Microscopic colitis
IBD
Colonic cancer
Medications
Diet
Bile acid diarrhoea
Pancreatic insufficiency
Coeliac disease
Overflow diarrhoea
Others e.g. hyperthyroidism, radiation enteritis, incontinence, SIBO etc
What investigations should be done for chronic diarrhoea?
FBC, U&Es, TFTs
Coeliac screen - TTG or EMA antibodies
Faecal calprotectin
Stool MCS and c.diff toxin screen
If the above dont reveal a cause then patients should undergo a flexible sigmoidoscopy or colonoscopy
Further investigations dependant on sympotms include… imaging, SeHCAT scan, lactose hydrogen breath test
What are considered normal bowel habits?
Vary on an individual basis but it is generally considered normal once every 3 days to 3 times a day
What is dysentery?
an infection of the intestines that causes diarrhoea containing blood and sometimes mucus
What can cause osmotic diarrhoea?
Disaccharide deficiencies
Drug-induced
Galactose
Generalised malabsorption
What can cause secretory diarrhoea?
Infections
Defects in intraluminal digestion and absorption
Excess laxative use
Outline how increased AND decreased gut motility can lead to diarrhoea?
Increased - lack of absorption due to rapid transit
Stasis - facilitates bacterial overgrowth which can cause diarrhoea
What can cause bloody diarrhoea?
Inflammation - IBD
Infection
Neoplasms
What is enterocolitis?
Inflammation of the intestines
Why has there been improved prevalence of infectious enterocolitis in the developed world?
Due to improved sanitation
What are the types of enterocolitis?
Infectious enterocolitis
Necrotising enterocolitis
Pseudomembranous colitis
Ulcerative colitis
Ischaemic colitis
Microscopic colitis
Allergic colitis in infants
Whats are the types of infectious enterocolitis?
Viral gastroenteritis
Bacterial enterocolitis
What is gastroenteritis?
Inflammation of the stomach and intestines
a transient disorder due to enteric infection with viruses, bacteria, or parasites. It is characterized by the sudden onset of diarrhoea, with or without vomiting
Whats the most common form of acute GI infection?
Gastroenteritis
Is viral or bacterial gastroenteritis more common?
Viral and so if often self limiting
What is food poisoning?
an illness caused by the consumption of food or water contaminated with bacteria and/or their toxins, or with parasites, viruses, or chemicals
What is travellers diarrhoea?
involves travel from high-income to lower- and middle-income countries and is defined as diarrhoea developing at the destination with at least one additional symptom, such as abdominal cramps, tenesmus, nausea, vomiting, fever, or faecal urgency
What is an outbreak defined as?
two or more cases associated in time and place
Outline the epidemiology of gastroenteritis?
Affects 1 in 5 people in the UK each year - common but deaths attributed to it is rare i.e. only 1 in 30 present to healthcare services
One of the leading causes of death in children under 5 in resource-limited countries
What proportion of cases of gastroenteritis will last <24 hours?
Up to 50%
How is gastroenteritis transmitted?
Faecal-oral
Food borne
Airborne e.g. vomiting
Environmental e.g. contaminated surfaces
Which bacteria are commonly implicated in food-borne gastroenteritis due to enterotoxins?
Staph aureus - enterotoxin B
Bacillus cereus
Clostridium perfringens type A
Vibrio cholera’s
Salmonella spp
Campylobacter spp
ETEC
How is food-borne gastroenteritis ‘food poisoning’ transmitted?
Primarily caused by enterotoxins produced by the microorganism rather than the microorganism itself
They produce a rapid onset after ingestion of food and typically last for <24 hours
Whats the cause of traveller’s diarrhoea?
In up to 70% of cases no specific causative agent is identified
The risk of this depends on destination, duration of exposure and host factors
What are common viruses that cause gastroenteritis?
Rotavirus
Norovirus
Adenovirus
What are the typical bacterial causes of watery diarrhoea?
C.diff
Clostridium perfringens
Enterotoxigenic E.coli (ETEC)
What are the typical bacterial causes of bloody diarrhoea?
Non-typhoidal salmonellosis
Campylobacter spp.
Shigella spp.
Yersinia enterocolitica
Enterohaemorrhagic E.coli (EHEC)
Whats the most common cause of viral gastroenteritis in children?
Rotavirus - prevalence decreasing due to introduction of rotavirus vaccine
Infection in adults is uncommon because immunity is long lasting
Whats the commonest cause of gastroenteritis in England and Wales?
Norovirus
Infection can occur in people of all ages because immunity is not long lasting
When does Norovirus prevalence increase in prevalence?
In colder months
What are the most commonly reported bacterial causes of infectious intestinal disease in England and wales?
Campylobacter spp.
How is rotavirus transmitted?
Most cases are transmitted by person-to-person spread by the faecal-oral route, or more rarely by contact with contaminated surfaces
What are symptoms of rotavirus?
watery diarrhoea and vomiting with or without fever and abdominal pain.
Vomiting usually settles within 1–3 days, and diarrhoea within 5–7 days, but can persist for 2 weeks.
How does Norovirus present?
Symptoms begin 24–48 hours after infection and last for 12–60 hours.
Sudden-onset nausea is followed by projectile vomiting and watery diarrhoea.
There may be associated fever, headache, abdominal pain, and myalgia.
Most people make a full recovery within 1–2 days.
How is Norovirus transmitted?
Faecal-oral route - person to person, or contaminated food/water or contact with contaminated surfaces
Outbreaks are common in semi-closed environments e.g. cruise ships, schools, hospitals
How does infection with campylobacter spp present?
Asymptomatic in 25-50%
Diarrhoea which may be bloody, nausea, vomiting, abdominal cramps and fever
Self-limiting mostly within 2-3 days and usually resolve within 1 week
How is campylobacter jejuni and campylobacter coli transmitted?
Consumption of contaminated food and drinks - undercooked meat (especially poultry), unpasteurised milk, untreated water
Whats the most commonly identified shiga toxin-producing E.coli in the UK?
E.coli 0157
Which groups of people does infection with E.coli 0157 affect?
Children under 5
Peak incidence in children 1-4
How does infection with E.coli 0157 present?
May be asymptomatic
Diarrhoea (may be bloody), fever, abdominal cramps, vomiitng
Self-limiting usually and resolved in 10 days
How is E.coli typically transmitted?
Through contaminated food - meat, salad products, water and unpasteurised milk
Faecal-oral route
Contact with infected animals - cattle, sheep, goats
Environmental exposure to contaminated water
What are the features of infection with salmonellosis?
Water and sometimes blood diarrhoea
Abdominal pain
Headache
Nausea
Vomiting
Fever
Illness usually starts within 3 days of exposure and resolves within a week
How is salmonellosis transmitted?
Contaminated food ingestion (most common) - red and white meats, raw eggs, milk, dairy products
Faecal oral
Contact with infected animals
How is shigellosis transmitted?
Faecal-oral route
More rarely - contaminated food or sexual transmission (men who have sex with men)
What age does shigellosis tend to affect? What time of year?
Children <5 most commonly but can occur at any age
Infections peak laste summer
How does shigellosis tend to present?
1-3 days after infection there is diarrhoea which may have blood and mucus. There is also fever, abdominal cramps, nausea, vomiting, headache and malaise
It typically resolves in 5-7 days
How common is gastroenteritis caused by yersinia enterocolitica? Who is most likely to get it?
Rare!
Children
How does infection with yersinia enterocolitica present?
Symptoms develop4-7 days after exposure and may last 2 days-6 weeks
Watery diarrhoa which is often bloody
Fever and abdominal pain
Lymphadenopathy
In older children or adults it can cause mesenteric lymphadenitis which causes RLQ abdominal pain which can give the impression of appendicitis