Infectious diarrhoea

Question 1

What is meant by “infectious diarrhoea”?

Answer 1

Diarrhoea ⇒ ≥3 loose or watery stools per day or more frequent passage than is normal for the individual

Question 2

What are the causes of infectious diarrhoea?

Answer 2

1. Viral Causes (most common) → norovirus, rotavirus, adenovirus
2. Bacterial Causes → campylobacter jejuni (after exposure to poultry), shigella, salmonella, e.coli (travellers diarrhoea), c.diff (antibiotic and PPI associated diarrhoea)
3. Parasitic → giardiasis, enterobiasis, amebiasis

Question 3

What are the risk factors for infectious diarrhoea?

Answer 3

recent travel (traveller’s diarrhoea), exposure to outbreak, recent hospitalisation (c.diff), medication use

Question 4

What are the different types of infectious diarrhoea you can have?

Answer 4

Acute Diarrhoea <14 days, Chronic Diarrhoea >14 days

Question 5

What are the presenting symptoms of infectious diarrhoea?

Answer 5

• Watery/Fatty/Bloody Stool → Sudden Onset
• Fever
• Abdominal Pain & Cramping
• N&V

Question 6

What presentations are associated with the different causative agents of infectious diarrhoea?

Answer 6

• Campylobacter Jejuni ⇒ most common cause of food poisoning commonly due to raw or undercooked meat, gram negative rods, bloody diarrhoea, precipitates Guillain-Barre Syndrome (GBS)
• Salmonella ⇒ eggs, poultry or contaminated food. Rose-coloured macules are bacterial emboli to the skin which typically occur in salmonella typhi and salmonella paratyphoid infection. They usually appear as a rash between day 5-10 of symptoms onset.
• Bacillus Cereus ⇒ symptoms start 30 mins to 6 hrs after exposure, rice and pasta.
• S.Aureus (short incubation period + severe vomiting) ⇒ starts 1-6hrs after exposure, profuse vomiting (only mild diarrhoea). unpasteurised milk, unrefrigerated meat and dairy products.
• Norovirus ⇒ projectile vomiting, highly infective, incubation period 12-24hrs. Norovirus is notorious for causing outbreaks of non-bloody vomiting and diarrhoea in healthcare institutions.
• E.Coli ⇒ 3-4 day incubation period, commonly after travel, causes bloody diarrhoea lasting up to a week.
• Entamobea Histolytica ⇒ contaminated water.
• Giardiasis ⇒ abdominal pain, bloating/flatulence, steatorrhoea, lethargy after ongoing diarrhoea and has recently travelled. Lactose intolerance can develop after giardisis.

Question 7

What are the incubation periods of the different causative agents responsible for infectious diarrhoea?

Answer 7

“Incubation Periods”: the time elapsed between exposure to a pathogenic organism, a chemical, or radiation, and when symptoms and signs are first apparent.
1. 1- 6 hrs: Staphylococcus aureus, Bacillus cereus
2. 12-48 hrs: Salmonella, Escherichia coli
3. 48-72 hrs: Shigella, Campylobacter
- 7 days: Giardiasis, Amoebiasis

Question 8

What investigations are used to diagnose/ monitor infectious diarrhoea?

Answer 8

1. Stool Culture → used to diagnose bacterial infections
2. U&E’s
3. PCR Test → viral infections
4. CRP & ESR → markers of inflammation

Question 9

How is infectious diarrhoea managed?

Answer 9

1. No Systemic Signs (Supportive Treatment) → bed rest, fluids and electrolyte replacement with oral rehydration therapy
2. Systemic Signs → admit + IV fluids + stool culture
3. Anti-Diarrhoeal Agents (eg. Loperamide)
4. Antibiotic Therapy (only prescribed when causative organism known)
   - C.difficile ⇒ oral vancomycin (add on IV metronidazole if severe)
   - Campylobacter (if severe) ⇒ clarithromycin