Infectious Diarrhoea

Question 1

Define diarrhoea vs dysentery vs gastro-enteritis?

Answer 1

Diarrhoea is increased frequency/fluidity of stool
Dysentery is colonic inflammation due to infection leading to bloody diarrhoea
Gastro-enteritis is 3 or more loose stools/day along with accompanying features of infection such as fever, vomiting, pain and blood/mucous in stool.

Question 2

What are the two different types of gastro-enteritis and example of each/

Answer 2

Inflammatory e.g. Shigella

Non-inflammatory e.g. Cholera or E. Coli

Question 3

Whats the main difference between inflammatory & non-inflammatory gastro-enteritis?

Answer 3

Non-inflammatory involves fluid secretions from the small intestine –> Frequent watery stools with little pain

Inflammatory involves invasion or toxin induced inflammation of the gut –> Pain, systemic upset e.g fever and bloody stools

Question 4

How is gastro-enteritis transmitted?

Answer 4

Contaminated food e.g. campylobacter in chicken
Bad food storage
Travel
Person-person

Question 5

Risk factors for gastro-enteritis?

Answer 5

• Food history (unreliable)
• Contacts
• Travel
• antimicrobials
• Occupation

Question 6

How do you test for gastro-enteritis?

Answer 6

Assess the patient:

• timing? >2wks it’s unlikely
• Risk Factors?
• Hydration? postural BP/Skin turgor/tachycardia/urine flow/muscle cramp
• Inflammation? Fever And WCC
• Electrolytes
• Stool/blood cultures
• Serology
• FBC, U&E + Creatinine
• AXR
• Sigmoidoscopy

Question 7

How is gastroenteritis treated?

Answer 7

Oral rehydration - Sodium chloride + glucose + AAs

Antimicrobials if:

• Traveller’s
• Severe
• Immunocompromised
• Co-morbidities e.g. renal/resp disease

Question 8

What are the major Gastroenteritis pathogens?

Answer 8

Campylobacter (Jejuni)
Salmonella
E. Coli
Shigella
cholera
C. Difficile

Giardia Lamblia
Cryptosporidium Parvum
Entamoeba Histolytica

Noravirus
Rotavirus

Question 9

Where does campylobacter infection come from?

Answer 9

Undercooked chicken

Question 10

How does Campylobacter Gastroenteritis present?

Answer 10

7 day incubation and clears within 3 wks
Abdo pain can be severe

Can have post-infective syndromes such as guillain barre or Reactive Arthritis

Question 11

how does Salmonella Gastroenteritis present?

Answer 11

<48hr incubation & lasts >10days (so shorter than campylobacter)

Can cause post-infective IBS

Question 12

What is the most dangerous form of E. Coli?

Answer 12

E. Coli O157:H7 aka enterohaemorrhagic E. coli

Question 13

Where do you get E. Coli O157:H7?

Answer 13

Cattle Reservoir;

• Contaminated Meat
• Stepping in Slurry
• Person-person

Question 14

How does E. Coli O157:H7 present

Answer 14

Haemolytic Uraemic Syndrome (HUS)
The toxin gets into the blood and causes platelet aggregation –> RBC & renal capillary damage –> Renal failure & anaemia

Question 15

What are the other forms of E.Coli other than O157:H7?

Answer 15

Enterotoxigenic - traveller’s Diarrhoea
Enteroinvasive
Enteropathogenic

Question 16

Describe Traveller’s Diarrhoea and the most common causes?

Answer 16

Diarrhoea usually <1wk, can be treated with Abx.

Mostly Enterotoxigenic E. Coli but also Campylobacter and Shigella

Question 17

What type of infectious diarrhoea can cause HUS & Seizures?

Answer 17

Shigella

E. Coli O157 causes HUS but not seizures

Question 18

Whats the main form of Antibiotic Associated DIarrhoea and what causes it?

Answer 18

Clostridium Difficile, it produces 2 toxins (A & B)

Mainly caused by the 4Cs:

• Cephalosporins
• Ceftriaxone (& other quinalones)
• Co-amoxiclav
• Clindamycin

Question 19

How do we detect C. Diff?

Answer 19

Stool Culture
Toxin Detection
Sigmoidoscopy

Question 20

How do we treat C. Diff?

Answer 20

• Metronidazole
• Oral Vancomycin (If severe)
• Fidaxomicin (For relapses)
• Stool Transplant
• Surgery

We’d also isolate symptomatic patients & follow hygiene

Question 21

List some parasites that can cause Diarrhoea?

Answer 21

• Giardia Lamblia
• Cryptosporidium Parvum
• Entamoeba Histolytica aka amoebic dysentery

Question 22

Where do we get Giardia Lamblia and how does it present?

Answer 22

Contaminated Water

Causes diarrhoea, malabsorption & Failure to thrive

Question 23

How do we detect Giardia Lamblia?

Answer 23

Sick patients - Vegetative form found on a duodenal biopsy

Asymptomatic patients have inactive cysts that can be detected on stool microscopy

Question 24

How do we treat Giardia Lamblia?

Answer 24

Metronidazole

Tinidazole

Question 25

How do we get Cryptosporidium Parvum?

Answer 25

Cattle Reservoir via infected water e.g. private water supplies out of cattle fields

Question 26

How do we detect and treat cryptosporium Parvum?

Answer 26

With stool microscopy looking for cysts

Usually its self-limiting

Question 27

How do we test for and treat Entamoebic Histolytica?

Answer 27

Duodenal biospy - Vegetative form in symptomatic patients
Stool Microscopy - Cysts in asymptomatic patients

Treated with metronidazole (Symptomatically) or furamide if asymptomatic

Question 28

What are the main viruses causing diarrhoea?

Answer 28

Rotavirus

Noravirus

Question 29

How do you test for Noravirus?

Answer 29

With Serum PCR

Question 30

How do we get & test for rotavirus?

Answer 30

Faecal-oral Route

Antigen Testing

Question 31

What are the main pathogens behind Food Poisoning?

Answer 31

1) Staph Aureus Toxins - survive cooking
2) Bacillus Cereus - re-heated rice
3) Clostridium Perfringens - Undercooked Meat