GI infections

Question 1

What is the general GI antibiotic?

Answer 1

Metronidazole

Question 2

What is dysentery?

Answer 2

Bloody diarrhoea w/ mucus

Question 3

What is infection of the biliary tract, liver and peritoneum usually a result of?

Answer 3

Spread of colonic flora (e.g. E. coli)

Question 4

Describe the shape of H. pylori

Answer 4

Gram -ve curved bacillus

Question 5

How does H.pylori protect itself from stomach acid?

Answer 5

Production of urease (formation of ammonia and CO2 from urea)

Question 6

How does H. pylori cause gastritis?

Answer 6

Causes a neutrophil influx (pro-inflam cytokines), CagA and VacA genes, ammonia

Question 7

how does H. pylori cause increased gastric acid production?

Answer 7

Increases parietal cell mass, inhibits D cells and stimulates G cells

Question 8

What diseases are linked with H. pylori infection?

Answer 8

Gastritis, peptic ulcers, GORD (–> barret’s oesophagus –> oesophageal adenocarcinoma)

Question 9

What investigations would you do to test for H. pylori infection?

Answer 9

Urea breath test 13C, stool Ag, endoscopy + biopsy

Question 10

What is the treatment for the eradication of H. pylori?

Answer 10

Omeprazole, amoxicillin + clarithromycin (I.e. 2 Abx + 1 PPI)

Question 11

What is gastroenteritis?

Answer 11

Infective diarrhoea

Question 12

What are some of the viral causes of infective diarrhoea?

Answer 12

Rotavirus (infants), norovirus, adenovirus

Question 13

What are some of the bacterial causes of infective diarrhoea?

Answer 13

E. coli, campylobacter jejuni, salmonella, shigella, C. difficile

Question 14

What are some parasitic causes of infective diarrhoea?

Answer 14

Cryptosporidium, giardia

Question 15

What are some non-infective causes of diarrhoea?

Answer 15

Coeliac disease, UC, Crohn’s, malignancy, tropical sprue hyperthyroidism

Question 16

What is the commonest cause of gastroenteritis (infective diarrhoea)?

Answer 16

Campylobacter jejuni

Question 17

What E. coli causes bloody diarrhoea? How?

Answer 17

EHEC - shiga-like toxin (1 + 2)

Question 18

What might you ask in a history if someone presents with diarrhoea?

Answer 18

Food handler? Travel? Pets?

Question 19

What is the commonest cause of traveller’s diarrhoea?

Answer 19

ETEC

Question 20

Give 3 parasitic causes of traveller’s diarrhoea?

Answer 20

cryptosporidiosis, giardiasis, amoebiasis

Question 21

Give a non-infectious cause of traveller’s diarrhoea

Answer 21

Tropical sprue

Question 22

How would you treat giardia and amoebiasis infections?

Answer 22

Metronidazole

Question 23

give 6 forms of E. coli?

Answer 23

ETEC, EHEC, EIEC, EPEC, EAEC, DAEC

Question 24

Which two forms of E. coli are toxin producing? What do they produce?

Answer 24

ETEC (produces LT [heat labile] and ST [heat stable]) and EHEC (shiga-like toxin 1 + 2)

Question 25

What does ETEC produce - what does this cause?

Answer 25

LT and ST toxins --> increase water loss from enterocytes (watery diarrhoea)

Question 26

What does EHEC produce - what does this cause?

Answer 26

Shiga-like toxins 1 and 2 --> bloody diarrhoea

Question 27

What does EIEC do?

Answer 27

It invades enterocytes causing them to die --> bloody diarrhoea

Question 28

What type of diarrhoea does EPEC produce - how does it do this?

Answer 28

It causes watery diarrhoea by adhering to the intestinal epithelium preventing the absorption of water

Question 29

What causes C. difficile?

Answer 29

It is an antibiotic associated diarrhoea - antibiotic misuse (such as fluoroquinolones)

Question 30

How does C. difficile stain?

Answer 30

gram +ve

Question 31

Does C. difficile produce spores?

Answer 31

Yes

Question 32

How is C. difficile spread?

Answer 32

Faeco-oral route

Question 33

What toxins does C. difficile produce? What do they do?

Answer 33

Toxins A and B --> increase permeability of the intestinal epithelium to water by reducing tight junctions between cells

Question 34

What type of diarrhoea does C. diff produce?

Answer 34

Watery

Question 35

How would you test for C. difficile?

Answer 35

Stool sample (GDH), ELISA (toxin A + B), tissue culture cytotoxicity assay

Question 36

What is the GOLD STANDARD investigation for C. difficile?

Answer 36

Tissue culture cytotoxicity assay

Question 37

What is the 1st and 2nd line antibiotic for C. difficile?

Answer 37

1st: metronidazole | 2nd line: vancomycin

Question 38

What are the features that separate diarrhoea in an immunocompromised host from a healthy host?

Answer 38

In immunocompromised: 1. lasts longer 2. broader range of causative organisms (such as CMV) 3. more severe presentation

Question 39

What are those who have B cell depletion (e.g. after using rituximab) at risk of? Why?

Answer 39

Giardia (a parasite) due to reduced IgE production

Question 40

When do HIV patients start to get opportunistic infection? When do they get diarrhoea related infections?

Question 41

Give a viral, bacterial and parasitic cause of diarrhoea in HIV patients with a CD4 count of

Answer 41

viral (CMV), bacterial (MAC), parasitic (cryptosporidium)

Question 42

What is unusual about the presentation of cryptosporidium parvum?

Answer 42

No fever

Question 43

What are the 3 types of liver abscesses?

Answer 43

Bacterial (pyogenic), hydatid cyst and amoebic liver abscess

Question 44

What are the sites of origin of bacteria that cause pyogenic liver abscesses? Give an example for each

Answer 44

Intestine (E. coli), dental source (K. pneumoniae), biliary tract...

Question 45

What are the symptoms of a pyogenic liver abscess?

Answer 45

Fever, weight loss, RUQ pain

Question 46

what are the signs of a pyogenic liver abscesses?

Answer 46

tachycardia, TENDER HEPATOMEGALY, fever

Question 47

What Ix's would you do to diagnose a pyogenic liver abscesses?

Answer 47

Blood cultures, US guided percutaneous aspirate

Question 48

What is the 1st and 2nd line treatment for a pyogenic liver abscesses?

Answer 48

1st line: co-amoxiclav and metronidazole | 2nd line: catheter drainage (US guided)

Question 49

What causes a hydatid cyst? How would you diagnose it?

Answer 49

Dog tapeworm - ELISA serology

Question 50

What is the treatment for a hydatid cyst?

Answer 50

Drainage + albendazole

Question 51

What is the treatment for an amoebic liver abscess?

Answer 51

Metronidazole