Infective Diarrhoea - Revision

Question 1

What is C. diff?

Answer 1

Gram positive rod bacteria

Question 2

What does C. diff diarrhoea typically follow?

Answer 2

Abx use - abx suppress normal gut flora

Question 3

What are the 5 most commonly implicated Abx in C. diff diarrhoea?

Answer 3

Broad spectrum:

1) cephalosporins
2) co-amoxiclav
3) clindamycin
4) ciprofloxacin (and other fluoroquinolones)
5) carbapenems

Question 4

How is C. diff transmitted?

Answer 4

Faeco-oral route

Question 5

What are 3 risk factors for C. diff ?

Answer 5

1) Abx use

2) PPI use

3) Healthcare settings

Question 6

How is a diagnosis of C. diff infection made?

Answer 6

1) C. diff antigen –> this only shows exposure to the bacteria, rather than current infection

2) C. diff toxin detection in stool

Question 7

What c. diff antigen is specifically tested for?

Answer 7

glutamate dehydrogenase

Question 8

Mx of C. diff infection?

Answer 8

Curent Abx therapy should be stopped.

1st line –> oral vancomycin for 10 days

Question 9

1st, 2nd and 3rd line therapies for C. diff infection?

Answer 9

1st –> oral vancomycin for 10 days

2nd –> oral fidaxomicin

3rd –> oral vancomycin + IV metronidazole

Question 10

What is medical management of RECURRENT C. diff infection:

a) within 12 weeks of symptom resolution
b) after 12 weeks of symptom resolution

Answer 10

a) oral fidaxomicin

b) oral vancomycin OR fidamoxicin

Question 11

Mx of life-threatening C. diff?

Answer 11

Oral vancomycin + IV metronidazole

Consider surgery

Question 12

What monoclonal Ab is sometimes used in the management of C. diff infection?

Answer 12

Bezlotoxumab –> targets C. difficile toxin B

Question 13

What may be considered in C. diff infection for patients who’ve had 2 or more previous episodes?

Answer 13

faecal microbiota transplant

Question 14

Complications of C. diff infection?

Answer 14

1) toxic megacolon

2) pseudomembranous colitis

3) bowel perforation & sepsis

Question 15

What is pseudomembranous colitis?

Answer 15

Characterised by inflammation in the large intestine, with yellow/white plaques that form pseudomembranes on the inner surface of the bowel wall.

Question 16

What severe complication can E.coli 0157 cause?

Answer 16

HUS

Question 17

How does E. coli 0157 cause HUS?

Answer 17

1) E. coli 0157 produces the Shiga toxin

2) Shiga toxin destroys RBCs, leading to HUS

Question 18

Why should Abx be avoided if E. coli gastroenteritis is considered?

Answer 18

Use of Abx increases risk of HUS

Question 19

How can HUS present?

Answer 19

Haemolytic anaemia, thrombocytopenia, and acute renal failure post 5–10 days of diarrhoea.

Question 20

What is the gold standard for diagnosing E. coli?

Answer 20

Stool culture & sensitivity

Question 21

Main mx of E. coli?

Answer 21

Supportive

Question 22

Which virus typically causes gastroenteritis with respiratory symptoms?

Answer 22

Adenovirus

Question 23

Does the presence of blood in acute diarrhoea indicate viral or bacterial cause?

Answer 23

Bacterial - consider campylobacter, E. coli 0157, Shigella

Question 24

Any child under 3 months old with what temperature should be urgently admitted to hospital?

Answer 24

> 38 degrees

Question 25

What is the most common causative organism of bacterial gastroenteritis?

Answer 25

Campylobacter

Question 26

Incubation period of campylobacter? How long do symptoms last?

Answer 26

2-5 days 3-6 days

Question 27

1st line Abx in Campylobacter?

Answer 27

Clarithromycin

Question 28

Classical blood test feature of C. diff infection?

Answer 28

Leukocytosis

Question 29

Treatment of Shigella?

Answer 29

Normally supportive

Question 30

What toxin does bacillus cereus produce?

Answer 30

Cerulide (reheating rice kills bacteria but not toxin)

Question 31

What is the most common cause of infective endocarditis in IVDU?

Answer 31

Staoph. aureus

Question 32

What is the key carrier of Yersinia enterocolitica?

Answer 32

Pigs (eating raw or undercooked pork can cause infection)

Question 33

What can Yersinia sometimes be confused with in older children?

Answer 33

Appendicitis: Older children and adults can present with right-sided abdominal pain due to mesenteric lymphadenitis (inflammation in the intestinal lymph nodes) and fever, which can give the impression of appendicitis.

Question 34

How is giardiasis transmitted?

Answer 34

Cysts released in faeces of mammals. The cysts may contaminate food or water. When eaten, they infect a new host (faecal-oral transmission).

Question 35

Treatment of giardiasis?

Answer 35

Tinidazole or metronidazole

Question 36

Who should be notified in suspected cases of food poisoning?

Answer 36

The UK Health Security Agency (UKHSA)

Question 37

Give some post-gastroenteritis complications:

Answer 37

1) Lactose intolerance 2) Reactive arthritis 3) IBS 4) Guillain–Barré syndrome 5) HUS

Question 38

1st line laxative in constipation?

Answer 38

Bulk forming e.g. ispaghula

Question 39

Symptoms of amoebiasis?

Answer 39

1) dysentry: profuse, bloody diarrhoea 2) liver abscess: usually a single mass in the right lobe (may be multiple): - RUQ pain - fever - systemic symptoms e.g. malaise - hepatomegaly 3) colonic abscess

Question 40

Mx of amoebiasis?

Answer 40

Metronidazole

Question 41

How does gastroenteritis caused by Staph. aureus present?

Answer 41

Severe vomiting & short incubation period

Question 42

How can giardiasis affect stool?

Answer 42

Can cause steatorrhoea

Question 43

Mx of giardiasis?

Answer 43

Metronidazole

Question 44

What is the purpose of the Yellow Card scheme in the UK?

Answer 44

Encourages healthcare professionals and patients to report any suspected adverse drug reactions, particularly those associated with new ('black triangle') drugs.

Question 45

What are black triangle drugs?

Answer 45

Medicines that are under intensive monitoring because they are either new to the market, or have very limited post-marketing exposure data.

Question 46

What is the most common cause of travellers' diarrhoea?

Answer 46

E. coli

Question 47

What does C. difficile antigen positivity show?

Answer 47

Only shows exposure to the bacteria, rather than current infection.

Question 48

What is the major dose-limiting side effect of magnesium salts?

Answer 48

Diarrhoea

Question 49

What is key in determining the severity of C. diff infection?

Answer 49

WCC

Question 50

NICE recommend a stool sample in what scenarios for diarrhoea?

Answer 50

1) the patient is systemically unwell and needs hospital admission, +/- antibiotics 2) blood or pus in the stool 3) immunocompromised 4) recently received Abx, PPIs or been in hospital 5) recent foreign travel 6) public health indication: diarrhoea in high-risk people (for example food handlers, healthcare workers, elderly residents in care homes), suspected food poisoning

Question 51

What is the most common cause of type II necrotising fasciitis?

Answer 51

Strep. pyogenes (gram +ve cocci)

Question 52

What triad is seen in HUS?

Answer 52

1) normocytic anaemia 2) thrombocytopenia 3) AKI

Question 53

Campylobacter diarrhoea is typically preceded by what?

Answer 53

A prodromal period e.g. fever, malaise and headache.