Diarrhoea

Question 1

What bacteria are sought in routine cultures of those with diarrhoea and their epidemiology?

Answer 1

Camplyobacter - 113/100,000 pop
Salmonella - 14/100,000 pop
Ecoli O157 - 150/yr

Question 2

What other bacteria cause diarrhoea, their epidemiology and the tests?

Answer 2

Shigella

Other forms of E. coli occasionally staph aureus, bacillus cereus, clostridium perfringens

Question 3

What parasites are commonly detected in stool specimens in the UK and their epidemiology?

Answer 3

Protozoa

• giardia duodenalis, approx 200/yr
• cryptosporidium parvum, 450-750/yr
• entamoeba histolytica

Question 4

What viruses commonly cause diarrhoea, their epidemiology and how are they detected?

Answer 4

Rotavirus <5y, 55,000yr
Diagnosed via antigen detection in stool

Norovirus, 1300-1500/yr
PCR

Question 5

What is: food poisoning, gastroenteritis, dysentery and colitis?

Answer 5

Food poisoning - illness caused by bacteria or other toxins in food, typically with vomiting and diarrhoea
Dysentery - obvious, large bowel inflammation, bloody stools
Gastroenteritis - is objective, 3 or more loose stools/day + accompanying features
Colitis -inflammation of lining of the colon

Question 6

What is the normal bowel flora and the hosts natural defences against enteric infections?

Answer 6

Stomach acidity
Normal gut flora
Immunity

Question 7

What is the epidemiology of bacterial and viral gastroenteritis?

Answer 7

Usually due to contamination of foodstuffs, poor storage or produce, travel related infections, person to person spread

Question 8

What measures are used to prevent the spread of enteric infection?

Answer 8

Hygiene
Reduce broad spectrum antibiotic prescribing
Wash hands between patients
Isolate those infected

Question 9

By what mechanisms can organisms produce diarrhoea?

Answer 9

Non inflammatory eg secretory toxin mediated - increased cAMP = loss of CL and Na and K = osmotic effect, massive loss of water (cholera, travellers diarrhoea)

Inflammatory eg inflammatory toxin damage and mucosal destruction

Question 10

What are the principles of managing gastroenteritis?

Answer 10

Assess symptoms and their duration
Risk of food poisoning
Assess hydration (risk of hyponatraemia, hypokalaemia)
Look for features of inflammation

Investigations: stool culture, blood culture, renal function, blood count, abdo X-ray or CT if distended, tender

Treatment: rehydration

Question 11

What are the potential complications of ecoli O157?

Answer 11

Haemolytic uraemic syndrome (haemolytic anaemia and renal failure)