1. Infectious diarrhoea

Question 1

How do you define gastro-enteritis

how do you define dysentery

Answer 1

Three or more loose stools/day
Accompanying fever

large bowel inflammation, bloody stools

Question 2

How do people contract gastro-enteritis?

Answer 2

Contamination of foodstuffs
Poor storage of produce
Travel related infections
Person to person spread

Question 3

What are the most common infectious agents that cause gastro-enteritis?

Answer 3

Campylobacter- 6,096
Salmonella- 751
E.coli 0157- 151

Question 4

What are the best defences against enteric infections?

Answer 4

Hygiene
Stomach acidity
Normal gut flora
Immunity

Question 5

What are the broad types of diarrhoeal illness?

Answer 5

Non inflammatory/secretory- E.g. Cholera

Inflammatory- e.g. Shigella dysentery

Mixed picture e.g. C-diff

Question 6

Describe the course of Non inflammatory diarrhoea?

Answer 6

Secretory/toxin mediated, e.g. cholerea increased cyclic AMP levels, drawing out chlorine and with it water. This leads to frequently watery stools with little abdo pain
rehydration is the mainstay of therapy.

Question 7

Describe the course of inflammatory diarrhoea

Answer 7

There is inflammatory toxin damage and mucosal damage. This leads to pain and fever.
Antimicrobials may be appropriate but rehydration alone is often sufficient

Question 8

What should you do to assess the patient

Answer 8

Assess the duration- over 2/52 weeks, unlikely to be Infective gastro-enteritis
Assess risk of poisoning (food,diet,contact)
Assess hydration- postural BP, skin turgor pulse
Look for features of inflammation- fever, WCC

Question 9

What is the major worry in patients with diarrhoea`

Answer 9

Fluid and electrolyte loss
Can lead to hyponatraemia due to sodium loss with fluid replacement by hypotonic solutions
Hypokalaemia due to potassium loss in stool

Question 10

How do you investigate a patient with diorrhoea

Answer 10

Stool culture +- molecular or Ag testing
Blood culture
Renal function
Blood count- neutrophilia, heamolysis (e.coli 0157)
Abdominal X-ray/CT if abdomen distended/tender

Question 11

What are your differential diagnosis?

Answer 11

Inflammatory bowel disease
Spurious diarrhoea (secondary to constipation)
Carcinoma
Sepsis (lack of abdo pain, no blood/mucous)

Question 12

How do you treat gastro-enteritis?

Answer 12

Rehydration therapy
oral- salt/sugar solution
IV- saline

Question 13

Describe the course of campylobacter gastroenteritis?

Answer 13

Up to 7 days after incubation so dietary history may be unreliable
Stools negative within 6 weeks
Abdominal pain can be severe
Post infection may develop gullain-barre or reactive arthritis
Specialised culture conditions
Mainly caused by C.jejuni and C.coli
chicken milk and puppies cause it
Isolated cases rather than outbreaks

Question 14

How do you look for the casing agent of gastro-enteritis?

Answer 14

Difficult to ind pathogen within normal flora
Selective and enrichment methods of culture necessary- variety of media and incubation conditions
Takes 3 days to complete all tests
Molecular detection and antigen detection

Question 15

Describe the course of salmonella gastroenteritis

Answer 15

Symptom onset usually <48 hours after exposure
Prolonged carriage of the bacteria
Post infective IBS common
Most common causes are S.enteritidis and s. typhimurium

Question 16

Describe the course of E.coli 0157

Answer 16

Infection from contaminated meat or person to person spread
Typical illness characterised by frequent bloody stools
E.coli 0157 produces shiga toxin, toxxin goes into blood
May cause heamolytic uremic syndrome

Question 17

What is haemolytic-uraemic syndrome?

Answer 17

Caused by shiga toxin produced by e.coli 0157
Causes heamoltic anaemia, thrombocytopenia and renal insufficiency
Symptoms abdo pain, bloody diarrhoea, fever, seizures, lethargy
Treatment mainly supportive, dialysis, no antibiotics, plamapharesis

Question 18

When do you give antibiotics in gastro-enteritis?

Answer 18

Hardly ever
Immunocompromised
Severe sepsis or invasive infection
Chronic illness e.g. malignancy

Question 19

Describe the course of C.diff

Answer 19

Typically HAI, caused by use of the 4 C’s
Cephalosporins, co-amoxiclav, clindamycin,ciprofloxacin
Produced enterotoxin and cytotoxin
Treat with metronidazole (frist line), oral vancomycin (high risk),
Stop precipitating antibiotics

Question 20

How do we prevent C.diff?

Answer 20

Avoid broad spectrum antibiotics
Avoid 4 C's
Antimicrobial management team (AMT) 
Isolate symptomatic patients
Wash hands between patients
Clean environments

Question 21

What do you do if you suspect someone has a parasite?

Answer 21

Microscopy diagnosis

Send stool with request for paracites, cysts and ova (PC and O)

Question 22

What is giardia duodenalis

Answer 22

Parasite causing cysts, diarrhoea, gas, failure to thrive
Transmitted by animals and food/water with faeces
Duodenal biopsy with parasite tightly bound to villi
Treat with metronidazole

Question 23

What is Cryptosporidium parvum

Answer 23

parasite causing diarrhoea, N+V, abdo pain
Caused by infected animals and water/food
oocysts seen on microscopy
No treatment required

Question 24

What is entamoeba histolytica?

Answer 24

Amoebic dysentery
Typically no bowel symptoms, causes liver, brain pleura abscess
intestinal disease metronidazole and luminal agent given to clear colony

Question 25

What is rotavirus?

Answer 25

Typically affect children under 5
Common in winter
Diagnose by antigen detection in school

Question 26

What is norovirus?

Answer 26

"winter vomiting bug"
Common cause of outbreaks in communities
Diagnosed by PCR
Very infectious
Strict infection control measures needed