Diarrhoea Flashcards
What is diarrhoea?
Increased frequency and volume of stool and decreased consitency
What would you want to establish in the history in someone who is presenting with acute diarrhoea?
Acute (<2 wks)
- Contact with D+V
- Fever/systemic upset
- Pain
- Blood/mucus
- Travel
- Diet change
- Contact with animals
- Associated symptoms
- Medications
- Social - drugs, alcohol
What would you want to ask in the history in someone who is presenting with chronic diarrhoea?
- Fever/systemic upset
- Pain
- Blood/mucus
- Travel
- Diet change
- Weight loss
- Nocturnal diarrhoea
- Symptoms of anaemia
What are causes of bloody diarrhoea?
- Campylobacter
- Shigella
- Salmonella
- E. Coli
- AMoebiasis
- IBD
- Colorectal cancer
- Colonic polyps
- Pseudomembranous colitis
- Ischaemic colitis
What are causes of diarrhoea with mucus?
- IBS
- Colorectal cancer
- Polyps
What are causes of diarrhoea with franck pus?
- IBD
- Diverticulitis
- Fistula/abscess
What are causes of “explosive” diarrhoea?
- Cholera
- Giardia
- Yersinia
- Rotavirus
What are causes of steatorrhoea?
- Pancreatic insufficiency
- Biliary obstruction
- Coeliac disease
- CF
What are non-GI causes of diarrhoea?
- Thyrotoxicosis
- Autonomic neuropathy
- Addison’s Disease
- Amyloidosis
- Pellagra
- Drugs
What are the common causes of diarrhoea?
- Gastroenteritis
- Traveller’s diarrhoea
- C. dioff
- IBS
- Colorectal cancer
- IBD
- Coeliac
What drugs can cause diarrhoea?
- Antibiotics
- Propranalol
- Cytotoxics
- Laxatives
- PPI’s
- NSAIDs
- Digoxin
- Alcohol
What bacteria can cause diarrhoeal illness?
- Salmonella
- Campylobacter
- E. coli 0157
- Shigella
- Clostridium Difficile
- Cholera
How long after onset do symptoms of Salmonella associated Diarrhoea present?
<48hrs
How long does Salmonella associated diarrhoea normally last for?
<10 days
What are the different types of diarrhoea?
- Osmotic Diarrhoea
- Secretory Diarrhoea
- Inflammatory Diarrhoea
- Abnormal motility
What can prolonged carriage of Salmonella be associated with?
Gallstone formation
What can be a common problem post-infection for someone who has had Salmonella?
Irritable Bowel Syndrome
What species of campylobacter is the main pathogen in diarrhoeal infection?
Campylobacter jejuni
What are the most common sources of campylobacter infection?
- Contaminated Milk
- Chickens
- Puppies
- Water
What is the incubation time for Campylobacter?
2-5 days
What are the main symptoms of Campylobacter infection?
- Severe Abdominal Pain - often becomes continuous and radiates to right iliac fossa
-
Watery Diarrhoea
- Can become bloody
- Fever
- Nausea and Vomiting
How long does it normally take for Campylobacter infection to clear?
3 weeks
How long does it take stools to become negative in Campylobacter infections?
6 weeks
What are some of the long term post-infective sequelae of Campylobacter infection?
- Guillain Barre Syndrome
- Reactive Arthritis
What is secretory diarrhoea?
Both active intestinal secretion of fluid and electrolytes as well as decreased absorption
Cholera toxin is regarded as the classic model of this
What are common causes of secretory diarrhoea?
- Enterotoxins
- Hormones
- Bile salts (in the colon) - following ileal resection
- Fatty acids (in the colon) - following ileal resection
- Some laxatives
What is the pathophysiology of diarrhoea caused by cholera?
- Increases cAMP levels
- Increases protein kinases
- Inhibit Na+ and Cl- absorption
- Cl- secretion

What bacteria cause secretory diarrhoea?
- Cholera
- E. Coli
- C. Difficile

How do you distinguish between secretory and inflammatory diarrhoea?
Inflammatory diarrhoea is accompanied by PAIN AND FEVER
What is osmotic diarrhoea?
Gut mucosa acts as a semipermeable membrane and fluid enters the bowel if there are large quantities of non-absorbed hypertonic substances in the lumen
What is inflammatory diarrhoea?
Damage to the intestinal mucosal cell so that there is a loss of fluid and blood
In addition, there is defective absorption of fluid and electrolytes

What can cause osmotic diarrhoea?
- Non-absorbable substance
- Malabsorption so that high concentrations of solute remain in the lumen
- Specific absorptive defect - coeliac disease
How can you distinguish between osmotic diarrhoea and other types of diarrhoea?
- Remove the malabsorptive substance
- Bloating?
What are the causes of inflammatory diarrhoea?
- Infection (Shigella)
- Inflammatory conditions (UC, Crohn’s)
What is the reservoirs of E. Coli O157?
Cattle

What can cause diarrhoea due to abnormal motility?
- Diabetic (arse)
- Post-vagotomy
- Thyrotoxicosis
What are the clinical features of Salmonella infection?
- Diarrhoea
- Vomiting
- Fever
- Septicaemia
What is Haemolytic Uraemic Syndrome (HUS)?
Shiga-Like Toxin (SLT) binds to globotriaosylceramide -> platelet activation stimulated -> microangiopathy
Platelets bind to endothelial, glomerular, tubular and mesangial cells

What type of E. Coli causes Enterohaemorrhagic E. Coli infection?
E. Coli O157:H7
What are the clinical features of E. Coli O157?
Frequent Bloody Stools
What can E. Coli O157 cause?
Haemolytic Uraemic Syndrome
Who does HUS most commonly occur in, if it does occur?
Children and the Elderly
How long after the onset of diarrhoea can it take for HUS to develop in E. Coli O157 infection?
5-9 days
What is the definition of Food Poisoning?
Illness caused by eating contaminated foodstuffs
What bacteria can cause food poisoning?
- Staphylococcus Aureus
- Bacillus cereus (re-fried rice)
- Clostridium Perfringens
What is Dysentery?
Infection of the intestine causing severe diarrhoea with blood and mucus
What causes bacillary dysentery?
Shigella
What are the symptoms of bacillary dystentery?
- Abdominal pain
- Small volume Bloody diarrhoea + mucus
- Sudden fever
- Nausea
What is the incubation period for bacillary dysentery?
1-6 days
How is bacillary dysentery spread?
Faecal-Oral
How is cholera spread?
Faecal-Oral route
Can you name the organism which causes cholera?
Vibrio Cholerae (Gram -ve rod)
How long does it take cholera to incubate?
A few hour to 5 days
What are the clinical features of Cholera?
- Profuse watery stools (1L/h)
- Fever
- Vomiting
-
Rapid dehydration
- Associated Metabolic Acidosis
What can be a complication of Shigella Infection?
- HUS
- Seizures
What is the definition of Colitis?
Inflammation of the colon
What are colitic symptoms?
- Recurring bloody diarrhoea +/- pus
- Lower Abdominal Pain
- Faecal Incontinence
- Fatigue
- Unexplained Weight loos
What is Gastroenteritis?
Inflammation of the stomach and intestine
What can cause Gastroenteritis?
Usually due to viral, bacterial infection or food-poisoning toxins
How do you objectively determine if someone has developed Gastro-enteritis?
3+ stools in 24 hrs, plus one of
- Fever
- Vomiting
- Pain
- Blood/mucus in stools
How long does gastroenteritis normally last?
3-5 days
What are the main features of gastroenteritis?
Dirrhoea +/- vomiting
What are the 4 main pathogenic mechanisms of bacterial gastroenteritis?
- Mucosal adherence - effacement of intestinal mucosa
- Mucosal invasion - Penetration and destruction of mucosa
- Toxin production enterotoxin - Fluid secretion without mucosal damage
- Cytotoxin - Damage to mucosa
For each of the 4 pathogenic mechanisms of bacterial gastroenteritis, describe their clinical presentations
- Mucosal adherence - Moderate watery diarrhoea
- Mucosal invasion - Dysentery
- Toxin Production - Profuse Watery diarrhoea
- Cytotoxin - Dysentery
What bacteria can cause gastroenteritis?
- Salmonella
- Campylobacter
- Shigella
- EHEC
- ETEC
- Cholera
What organism causes pseudomembranous colitis?
C. Difficile
How does C. diff cause diarrhoea?
- Toxin A - enterotoxin
- Toxin B - cytotoxic
How does C. diff infection present?
- Severe Bloody Diarrhoea
- Abdominal Pain
- Gut perforation
- Pyrexia
- Toxic Megacolon
What are the 4 C’s which put a patient at risk of C. diff colonisation?
- Cephalosporins
- Clindomycin
- Ciprofloxacin
- Co-Amoxiclav
How would you manage someone with C. diff infection?
Stop causative ABx
10 days of treatment
- Non severe - Metranidazole - 400 mg 8hrly
- Severe - Oral Vancomycin - 125 mg 6 hrly
What parasites can cause diarrhoea?
- Cryptosporidium parvum
- Giardia lamblia
- Entamoeba histolytica
What can be a complication of Entamoeba Histolytica?
Amoebic Liver Abscess
How does amoebiasis present?
-
Amoebic dysentry - Similar to ulcerative colitis
- Profuse Diarrhoea +/- blood
- Can have fever
- Abdo pain
- Amoebic colonic abscess
-
Amoebic liver abscess
- High, swinging fever
- Sweats
- RUQ pain/tenderness +/- chest pain
How does giardia infection present?
- Explosive Diarrhoea
- Malabsorption
- Bloating
- Flatulence
- Weight loss
Where does giardia colonise in the gut?
Duodenum and jejunum
How would you treat giardia infection?
- Metranidazole
- Tinidazole
How does Rotavirus cause diarrhoea?
Infects mature enterocytes of villous body and tip (not crypts) with cell death and lactose intolerance
How would you clinically assess someone with acute diarrhoea?
- Assess hydration - postural BP, skin turgor, pulse, mucus membranes, CRT
- Features of infection - fever, raised WCC, rashes
- Consider PR exam
How would you investigate someone with suspected gastro-enteritis?
- Stool culture
- Blood culture
- Renal function
- Blood count - neutrophilia, haemolysis
- Abdominal X-Ray - if abdomen distended, tender
What would make you suspect a non-infectious cause for diarrhoea?
>2 weeks duration
How would you clinically assess someone with chronic diarrhoea?
- Assess hydration - postural BP, skin turgor, pulse, mucus membranes, CRT
- Features of infection - fever, raised WCC, rashes
- Signs of underlying cause - WL, clubbing, anaemia, oral ulcers, rashes, abdo mass/scars, thyroid status
- Consider PR exam
What investigations would you consider doing in someone with diarrhoea?
- Bedside - Basic observations
- Bloods - FBC, ESR, CRP, U+E’s, TFTs, Coeliac serology
- Other - stool cultures, faecal elsatase, Lower GI endoscopy
What might decreased MCV on FBC in someone with diarrhoea suggest?
- Bleeding
- Iron deficiency - coeliac, colon cancer
What might increased MCV on FBC investigation indicate in someone with diarrhoea?
- Alcohol abuse
- B12 deficiency due to coeliac/crohn’s
What might increased ESR/CRP indicate in someone with diarrhoea?
- Infection
- Crohn’s
- UC
- Cancer
What might you see on U+E’s in someone with diarrhoea?
- Hypokalaemia - if severe
- Features of dehydration
If someone presented with what you deemed to be infective diarrhoea, when would you consider symptomatic treatment without further investigation?
No systemic signs
If someone presented with what you deemed to be infective diarrhoea with systemic features (fever, dehydration, visible blood), how would you manage them?
Admit:
- Oral fluids
- Consider empirical Abx unless non-infectious cause found
- Faecal culture
How would you manage diarrhoea?
- Treat cause
- Oral rehydration initially, unless severe -> IV
What is toxic megacolon?
Usually a complication of inflammatory bowel disease, such as ulcerative colitis and, more rarely, Crohn’s disease, and of some infections of the colon, including C. diff infections (pseudomembranous colitis).
Other forms of megacolon exist and can be congenital (present since birth, such as Hirschsprung’s disease). It can also be caused by Entamoeba histolytica and Shigella.
What is the major cause of traveller’s diarrhoea?
Enterotoxigenic E. Coli
How would you detect c. diff?
- FBC - WBC
- Stool PCR followed by specific ELISA immunoassay for toxins
- Consider AXR - significant distention
What imaging would you consider in someone with c. diff infection?
AXR - look for toxic megacolon
What are infective causes of non-bloody diarrhoea?
- Norovirus
- Rotavirus
- Anteric Adenovirus
- Enterotoxigenic E. Coli
- Enteropathogenic E. Coli
- Toxin-producing s. aureus
- Cholera
- C. perfingens
- Giardia
- Cryptosporidium
How would you manage someone with cholera?
- Oral rehydration salts - may need 1L/hr initially
- Consider IV fluids if severly dehydrated + ORS
- Consider Abx - doxycycline/tetracycline
How would you investigate suspected amoebiasis?
- Bloods - LFT’s, U+E’s, serum antiamoebic antibody
- Orifices - Stool culture/microscopy, Faecal antigen
- Imaging - Abdo USS, CT +/- aspiration (abscess), sigmoidoscopy
- Specific - Stool/Liver pus PCR
What features might you see on sigmoidoscopy in amoebiasis?
- Friable mucosa
- Mucosal ulceration
- Amoebomas
- Colonic abscesses
How would you treat amoebiasis?
- Metranidazole, then diloxanide fuorate - to destroy gut cysts
- Consider tinidazole - severe infection or liver abscess
What might you see on microscopy of stool culture in amoebiasis?
Cysts and trophozoites
What might serology for amoebiasis show?
Antibody titres elevated