Gastroenteritis

Question 1

Is gastroenteritis only caused by infection?

Answer 1

No, can have many different causes, not just infective

Question 2

The faecal flora is estimated to have a metabolic capacity equal to what organ?

Answer 2

The liver

Question 3

What are the 3 main beneficial affects of the commensal flora of the gut?

Answer 3

1) Metabolism
2) Colonisation resistance
3) Antibody induction

Question 4

What is thought to have a profound effect on the composition of gut flora?

Answer 4

Diet

Question 5

Which 2 vitamins are secreted by enteric bacteria?

Answer 5

Vitamins K and B12

Question 6

We are born sterile, what is the difference in the flora of bottle fed babies compared to breast fed babies?

Answer 6

Bottle fed - adult microflora

Breast fed - bifidobacteria

Question 7

Are the bacteria in the gut mainly anaerobes or aerobes?

Answer 7

Obligate anaerobes (cant survive in presence of oxygen)

Question 8

What are facultatively anaerobic bacteria?

Answer 8

Can survive in presence or absence of oxygen

Question 9

What are the 4 most common commensal flora of the gut, what kind of bacteria are they?

Answer 9

1) Bacteroides (anaerobic GNB)
2) Clostridium perfringens (anaerobic GPB)
3) Escherichia coli (Facultative GNB)
4) Enterococcus faecalis (Facultative GPC)

Question 10

Globally there are roughly how many cases of diarrhoeal disease every year?

Answer 10

1.7 billion

Question 11

What is the leading cause of malnutrition in children under 5 years old?

Answer 11

Diarrhoea

Question 12

What are the 8 common bacterial causes of gastroenteritis?

Answer 12

1) Salmonella
2) Shigella
3) E coli
4) Campylobacter
5) Vibrio cholera
6) Clostridium difficile
7) Staph aureus
8) Bacillus cereus

Question 13

What are the 3 common parasitic causes of gastroenteritis?

Answer 13

1) Entamoeba hist.
2) Giardia lamblia
3) Cryptosporidium

Question 14

Have outbreaks of foodbourne diseases in England and wales increased or decreased?

Answer 14

Decreased - mainly due to salmonella - more education and better food standards

Question 15

Have outbreaks of non-foodborne diseases increased or decreased?

Answer 15

Increased - often related to recreational water or animal contact

Question 16

What are the 5 main presenting complaints for gastroenteritis?

Answer 16

1) Acute onset
2) Vomiting
3) Diarrhoea - frequency, mucous, blood
4) Abdominal pain
5) Systemic effects - fever etc.

Question 17

What are the 6 complications of gastroenteritis?

Answer 17

1) Dehydration
2) Renal failure
3) HUS - haemolytic urea syndrome
4) Toxic megacolon
5) Guillan barre syndrome
6) Dissemination of salmonella

Question 18

What are the 3 main investigations in gastroenteritis?

Answer 18

1) Bloods - FBC, U&E, CRP, blood cultures
2) Abdo XR if severe
3) Stool analysis

Question 19

What 4 tests may be used to analyse a stool in gastroenteritis?

Answer 19

1) Ova, parasites and cysts ‘OCP’
2) Microscopy, culture and sensitivity ‘MC&S’
3) Clostridium difficile toxin ‘CDT’
4) Viral PCR

Question 20

Name one common viral gastroenteritis?

Answer 20

Norovirus

Question 21

Norovirus incidence is higher in which season?

Answer 21

Winter

Question 22

What are the 2 main symptoms of norovirus?

Answer 22

1) Diarrhoea

2) Projectile vomiting

Question 23

How long does norovirus tend to last, is it dangerous?

Answer 23

24-48 hours, not dangerous

Question 24

How is norovirus spread?

Answer 24

Via aerosols which come off the vomit of infected people

Question 25

How is norovirus managed?

Answer 25

Manage dehydration and let illness take its course, stay away from others and diligent hand washing to prevent transmission

Question 26

What are the 3 main causes of parasitic gastroenteritis?

Answer 26

1) Cryptosporidium 2) Giardia 3) Entamoeba

Question 27

Cryptosporidium is transmitted how?

Answer 27

Predominantly water borne disease which is spread via contaminated drinking water, swimming pools etc.

Question 28

Why is cryptosporidium commonly spread via swimming pools?

Answer 28

Oocytes are resistant to chlorine based disinfectants

Question 29

Is cryptosporidium infection more common in the first or second half of the year, why?

Answer 29

Second half - related to foreign travel and summer holidays

Question 30

Via which 2 mechanisms can bacteria cause gastroenteritis?

Answer 30

1) Enterotoxin production - toxin produced by bacteria attacks host enterocytes 2) Adherence or invasion of enterocytes by bacteria itself

Question 31

Other than gastroenteritis what other infection does E coli commonly cause?

Answer 31

UTI

Question 32

Via what mechanism does E coli cause gastroenteritis?

Answer 32

Enterotoxin production

Question 33

10-15% of patients with gastroenteritis caused by E coli also develop what complication and why?

Answer 33

Haemolytic urea syndrome | Toxin affects RBCs too

Question 34

How does E coli infection lead to inflamed and fluid filled bowel?

Answer 34

1) Toxin produced which is internalised by epithelial cells 2) Toxin affects small proteins so that Cl- moves out of the cell followed by Na+ 3) High electrolyte content in the lumen also pulls water out in the lumen by osmosis - leading to a fluid filled lumen and dehydration

Question 35

What are the 4 main types of salmonella?

Answer 35

1) S. typhi 2) S. paratyphi 3) S. enteritidis 4) S. typhimurium

Question 36

What 3 conditions does salmonella cause?

Answer 36

1) Food poisoning 2) Typhoid 3) Paratyphoid

Question 37

What is the treatment for infective gastroenteritis?

Answer 37

Supportive management. Generally avoid Abx as this may increase duration of salmonella carriage Abx treatment may also worsen E coli HUS (Haemolytic urea syndrome)

Question 38

What is the difference between tyhpoidal salmonella and non-typhoidal salmonella?

Answer 38

Typhoidal salmonella can disseminate to other cells outside of the GIT and cause typhoidal fever

Question 39

Why does Abx associated diarrhoea occur?

Answer 39

Due to disruption of the gut microflora which leads to a change in metabolism (carbohydrates/bile acids) and overgrowth of pathogenic organisms

Question 40

What are the symptoms of Abx associated diarrhoea?

Answer 40

Range from mild diarrhoea to pseudomembranous colitis and can lead to conditions such as toxic megacolon, perforation and shock

Question 41

What is the most common cause of Abx associated diarrhoea?

Answer 41

C. diff - accounts for 10-25%

Question 42

Other than C diff what 5 organisms can cause Abx associated diarrhoea commonly?

Answer 42

1) C perfringens 2) S aureus 3) Candida spp 4) Klebsiella spp 5) Salmonella spp

Question 43

Risk of C diff infection increases massively with increasing...?

Answer 43

Age

Question 44

What strain of C diff is associated with a 2.5-3.5 fold increased death rate and deaths in younger people?

Answer 44

CD 027

Question 45

What 2 Abx are high risk for C diff infection?

Answer 45

1) Cephalosporins | 2) Clindamycin

Question 46

What 4 Abx are medium risk for C diff infection?

Answer 46

1) Ampicillin/amoxicillin 2) Co-trimoxazole 3) Macrolides 4) Fluoroquinolones

Question 47

Which Abx is CD 027 resistant to and is therefore of particular importance?

Answer 47

Fluoroquinolones

Question 48

What are the 8 CD infection control measures?

Answer 48

1) Early warning system to identify changes in epidemiology 2) Reduce risk of transmission 3) Early isolation/cohorting of patients with diarrhoea 4) Environmental cleaning, chlorine 5) Hand hygiene soap & water 6) Examine/optimise/reduce overall Abx use 7) Limit high risk agents in high risk patients 8) Feedback CDI and Abx data on a regular basis

Question 49

What 2 Abx are the current therapy for CD infection and what is the new Abx?

Answer 49

Current: Oral metronidazole/ oral vancomycin New: oral fidaxomicin

Question 50

Other than Abx what is the other treatment for C diff?

Answer 50

Faecal transplant