Infectious Diarrhoea

Question 1

What is clinical definition of gastro-enteritis?

Answer 1

• three or more loose stools/day - accompanying features

Question 2

What is dysentery?

Answer 2

• large bowel inflammation, bloody stools

Question 3

What are the 7 types of faeces on the bristol stool chart?

Answer 3

Type 1 - separate hard lumps Type 2 - Sausage shaped but lumpy Type 3 - sausage shaped but cracked Type 4 - like a sausage or snake, smooth Type 5 - soft blobs with clear cut edges Type 6 - fluffy pieces with ragged edges Type 7 - entirely liquid

Question 4

What are the 4 common causes of gastroenteritis?

Answer 4

• contamination of food stuffs - poor storage of food stuffs - travel related infections - person to person spread

Question 5

What is the most common causative pathogen of gastroenteritis?

Answer 5

Viruses are commonest cause with campylobacter being the commonest bacterial pathogen.

Question 6

Which pathogen causes the most hospital admissions per year?

Answer 6

Although campylobacter is the most common causative pathogen, salmonella causes the most admissions per year (around 2500)

Question 7

Which food is most commonly linked with food poisoning?

Answer 7

• Poultry meat

Question 8

Which pathogen causing GE is on the rise?

Answer 8

E. Coli

Question 9

What are the 4 main defences we have against enteric infections?

Answer 9

• Hygiene - Stomach acidity - Normal flora - Immunity

Question 10

What 3 different types of diarrhoeal infection?

Answer 10

1. Non-inflammatory/secretory (cholera) 2. Inflammatory (shigella dysentery) 3. Mixed picture (c. difficile)

Question 11

What causes the effects in non-inflammatory diarrhoeal infection?

Answer 11

It is secretory toxin mediated: causes rise in cAMP and Cl secretion.

Question 12

What are the symptoms of non-inflammatory diarrhoea? Tx?

Answer 12

• Frequent watery stools with little abdo pain - oral rehydration salts

Question 13

What causes the effects in inflammatory diarrhoea?

Answer 13

Inflammatory toxin damage and mucosal destruction

Question 14

What are the symptoms of inflammatory diarrhoea? Tx?

Answer 14

• Diarrhoea, pain and fever - Antimicrobials may be appropriate but rehydration alone is often sufficient

Question 15

What are RF for food poisoning?

Answer 15

BBQ (dietary) Contact Travel history

Question 16

How long does it take for suspection of infective gastro-enteritis?

Answer 16

10-14 days at least, some hospitals will not admit until past this threshold

Question 17

How do we access hydration?

Answer 17

Postural BP Skin turgor Pulse

Question 18

What are common findings on assessment for infective gastro-enteritis in infants?

Answer 18

Sunken eyes and cheeks Sunken fontanelles Sunken abdomen Few or no tears Decreased skin turgor Dry mouth

Question 19

What is lost from the body during severe secretory diarhoea?

Answer 19

1-7 l fluid per day containing 80-100 mmol Na Hyponatraemia due to sodium loss with fluid replacement by hypotonic solutions Hypokalaemia due to K loss in stool (40-80mmol/l of K in stools)

Question 20

What are the investigations for diarrhoea?

Answer 20

3 stool cultures until satisfied. Blood are rarely positive Renal functions will check how sodium is doing Haemolysis is useful as will show haemolytic anaemia

Question 21

DDx for diarrhoea?

Answer 21

• IBD - Spurious diarrhoea (secondary to constipation) - Carcinoma

Question 22

Tx for diarrhoea?

Answer 22

Depending on severity - oral rehydration salts (H2O + salt + glucose) - IV fluids

Question 23

What are symptoms of campylobactor infection?

Answer 23

abdominal pain can be severe <1% invasive

Question 24

How are different strains of pathogen identified?

Answer 24

• difficult to find pathogen in the midst of complex normal flora - selective and enrichment methods of culture necessary - variety of media and incubation conditions - takes 3 days to complete all tests

Question 25

What are signs and symptoms of salmonella gastroenteritis?

Answer 25

- symptom onset usually \<48 hrs after exposure - diarrhoea usually lasts \<10 days - \<5% positive blood cultures - 20% patients still have positive stools at 20/52 - Prolonged carriage may be associated with gallstones - Post-infectious IBS is common

Question 26

How can we differentiate out the different sub-species of salmonella?

Answer 26

Salmonella is a non-lactose fermenter Salmonella remains a beige colour on agar Only way to separate out sub-species of salmonella is by looking at the antigens

Question 27

What are the most common strains of salmonella in the UK?

Answer 27

Salmonella enteritidis and Salmonella typhimurium

Question 28

How does E. Coli spread?

Answer 28

contaminated meat or person-to-person spread (low incoulum)

Question 29

What is E coli illness characterised by?

Answer 29

Typical illness characterised by frequent bloody stools

Question 30

What can the E. coli toxin cause?

Answer 30

Toxin can cause hemolytic-uraemic (HUS) syndrome (haemolytic anaemia and renal failure). HUS: renal failure, haemolytic anaemia and thrombocytopenia. Treatment supportive – antibiotics NOT indicated

Question 31

When are antibiotics indicated in gastroenteritis?

Answer 31

immunocompromised severe sepsis or invasive infection valvular heart disease chronic illness diabetes

Question 32

What causes a clostridium difficile infection?

Answer 32

Some gut bacteria will be effected by antibiotics – this causes inbalance which will allow c diff infection

Question 33

What are the main drivers of inflammation on a c.diff infection?

Answer 33

Produces toxins which are thought to be the main drivers of inflammation

Question 34

How can we avoid c.diff infection?

Answer 34

Reduction in broad spectrum antibiotic prescribing Avoid 4 Cs – cephalosporins, co-amoxiclav, clindamycin, clarithromycin

Question 35

What is the management of c.diff infection?

Answer 35

Stop precipitating antibiotic (if possible) Follow published treatment algorithm – oral metronidazole if no severity markers Oral vancomycin if 2 or more severity markers

Question 36

What is a protozoa?

Answer 36

single cell parasite

Question 37

What is a helminth?

Answer 37

worm parasite

Question 38

How do we diagnose parasites?

Answer 38

Send stool with request “parasites, cysts and ova please” or P, C and O

Question 39

What is the UK parasite? How does it infect and what are the symptoms?

Answer 39

Giardia Lamblia - contaminated water - diarrhoea, malabsorption and failure to thrive

Question 40

What are the causes of viral diarrhoea?

Answer 40

Adenovirus Rotavirus in children under 5 Norovirus

Question 41

How is norovirus diagnosed?

Answer 41

Diagnosis by PCR - ward closures are common - strict infection measures needed