Infectious Diarrhoea

Question 1

What is the definition of gastroenteritis?

Answer 1

Three or more loose stools a day with accompanying features

Question 2

What is dysentery?

Answer 2

Large bowel inflamm. with bloody stools

Question 3

What are the causes of gastroenteritis?

Answer 3

Contamination of foodstuffs, poor storage of produce, travel related infections and person to person spread

Question 4

What is the most common cause of gastroenteritis?

Answer 4

Viruses

Question 5

What is the most common bacteria associated with gastroenteritis?

Answer 5

Campylobacter

Question 6

Which pathogen causes the most food poisoning related hospital admissions?

Answer 6

Salmonella

Question 7

What defences are there against enteric infections?

Answer 7

Hygiene, stomach acid, normal gut flora and immunity

Question 8

What are the types of diarrhoeal illness?

Answer 8

Non-inflammatory/secretory (cholera etc.), inflammatory (shigella dysentery etc.) and mixed (C. difficile etc.)

Question 9

What is the clinical presentation of non-inflammatory diarrhoeal illness and what is the treatment?

Answer 9

Frequent watery stools with little abdo pain - rehydration

Question 10

How is diarrhoea produced in cholera?

Answer 10

Increased cAMP causes the loss of Cl from cells along with Na and K. The osmotic effect leads to massive loss of water from the gut

Question 11

What is the pathophysiology of inflammatory diarrhoeal disease?

Answer 11

Inflammatory toxin damage and mucosal destruction

Question 12

What is the clinical presentation of inflammatory diarrhoea disease and what is the treatment?

Answer 12

Pain and fever - rehydration +/- antimicrobials

Question 13

What investigations can be done in a patient with diarrhoea?

Answer 13

Stool culture +/- molecular/Ag testing, blood culture, renal function, FBC and abdo XRay/CT if abdomen is distended/tender

Question 14

What are the differential diagnosis for diarrhoea?

Answer 14

IBD, spurious diarrhoea (secondary to constipation) and carcinoma

Question 15

What is the treatment of gastroenteritis?

Answer 15

Rehydration

• Oral salt/sugar solution
• IV saline

Question 16

What are the features of campylobacter gastroenteritis?

Answer 16

7 days incubation, stools negative within 6 weeks, severe abdominal pain and post-infection sequelae (Guillian-Barre syndrome and reactive arthritis)

Question 17

What are the two modes of bacterial culture?

Answer 17

Molecular detection and antigen detection

Question 18

What are the sources of campylobacter infection?

Answer 18

Chickens, contaminated milk and puppies

Question 19

What is the clinical presentation of salmonella gastroenteritis?

Answer 19

Symptom onset < 48hrs after exposure, diarrhoea, prolonged carriage may be associated with gallstones and post-infectious irritable bowel

Question 20

What are the common types of salmonella isolates found in Scotland?

Answer 20

S enteritidis and S typhimurium

Question 21

What are the features of an E coli infection?

Answer 21

Spread from contaminated meat/person to person spread, frequent bloody stools, Shiga toxin produced (only toxin enters the blood) and can cause haemolytic-uraemic syndrome

Question 22

What is haemolytic-uraemic syndrome and how is it treated?

Answer 22

Haemolytic anaemia, renal failure and thrombocytopenia. Treatment is supportive (NO antibiotics)

Question 23

What other bacteria can cause gastroenteritis?

Answer 23

Shigella and other forms of E. coli

Question 24

Name the rarer causes of food poisoning

Answer 24

Staph aureus, bacillus cereus and clostridium perfringens

Question 25

When are antibiotics indicated in gastroenteritis?

Answer 25

In patients who are immunocompromised, have severe sepsis/invasive infection or have a chronic illness e.g. malignancy

Question 26

What is the typical clinical presentation of a patient with C. Diff infection?

Answer 26

PH of antibiotics and diarrhoea (from mild to severe colitis

Question 27

What is the treatment of a patient with C. Diff infection?

Answer 27

Metronidazole/Oral vancomycin, stool transplants and surgery (if required)

Question 28

How can C. Diff infections be prevented?

Answer 28

Reduction in broad spectrum antibiotic prescribing (avoid 4 Cs)

Question 29

Which 4 antibiotics should be avoided to prevent C Diff infections?

Answer 29

Cephalosporins, co-amoxiclav, clindamycin and ciprofloxacin

Question 30

Which protozoa can cause diarrhoea?

Answer 30

Giardia duodenalis, cryptosporidium parvum and entamoeba histolytica

Question 31

What are the featues of infection with giardia duodenalis?

Answer 31

-Diarrhoea, gas, malabsorption and failure to thrive Transmitted by direct contact with cattle/cats/dogs/other people and food/water contaminated with faeces -Cysts seen on stool microscopy -Trophozoites: tightly bound to villi (duodenal biopsy) or string test

Question 32

How is a giardia duodenalis infection treated?

Answer 32

Metronidazole

Question 33

What are the features of infection with Cryptosporidium parvum?

Answer 33

- Diarrhoea, nausea, vomiting and abdo pain - Infected animals/faeces and contaminated water/food - Oocysts seen on microscopy - No treatment usually required

Question 34

What are the features of infection with Entamoeba histolytica?

Answer 34

- Amoebic dysentery - Liver/pulmonary/brain abscess months/years later - Microscopy: trophozoites in symptomatic patients and cysts in formed stool in asymptomatic patients - Antibody detection for invasive disease

Question 35

What is the treatment of Entamoeba histolytica infection>

Answer 35

Metronidazole + luminal agent

Question 36

What are the features of rotavirus?

Answer 36

- Children under 5 - Common in winter - Diagnosed by antigen detection on stool - Vaccine introduced in 2013

Question 37

What are the features of norovirus?

Answer 37

- Winter vomiting bug: diarrhoea and vomiting - Outbreaks common (hospitals, schools, cruise ships etc.) - Diagnosed by PCR - Needs strict infection control measures