infectious diarrhoea

Question 1

what are the causes of gastro-enteritis ?

Answer 1

contamination of foodstuffs
poor storage of produce
travel related infection
person to person spread

Question 2

what is the most common cause of GI infection ?

Answer 2

viruses

Question 3

what are the three most common bacterium which cause food poisoning ?

Answer 3

campylobacter
salmonella
E.coli

Question 4

what are defences against enteric infections ?

Answer 4

hygiene
stomach acidity
normal gut flora
immunity

Question 5

what are the different clinical features of diarrhoeal illness and what causes them ?

Answer 5

non-inflammatory/secretory - cholera
inflammatory - shigella dysentry
mixed picture - C. difficile

Question 6

what are the features of non-inflammatory diarrhoea ?

Answer 6

secretory toxin-mediated- cholera increases cAMP levels and Cl secretion, enterotoxin E.coli same
frequent watery stools with little abdominal pain
rehydration is mainstay

Question 7

what are the features of inflammatory diarrhoea ?

Answer 7

pain and fever
inflammatory toxin damage and mucosal destruction
bacterial infection/amoebic dysentry
Abx may be appropriate but rehydration is often enough

Question 8

what is important when assessing the patient with diarrhoea ?

Answer 8

symptoms and duration - >2/52 unlikely to be infective GE
risk of food poisoning-dietary, contact, travel
assess hydration- postural BP, skin turgor, pulse
features of inflammation- fever, raised WCC

Question 9

what happens to electrolyte balance in diarrhoea ?

Answer 9

hyponatraemia

hypokalaemia

Question 10

what investigations should be done for diarrhoea ?

Answer 10

stool culture + Ag testing
blood culture
renal function
blood count - neutrophilic, haemolysis
abdo x-ray/CT

Question 11

what are the differential diagnosis for diarrhoea ?

Answer 11

inflammatory bowel disease
spurious diarrhoea - secondary to constipation
carcinoma
sepsis

Question 12

what signs indicate diarrhoea may be caused by sepsis ?

Answer 12

lack of abdominal pain/tendernes

no blood/mucus in stools

Question 13

how do you treat gastro-enteritis ?

Answer 13

rehydration IV/Oral

salt/sugar solution

Question 14

what are features of campylobacter GE ?

Answer 14

up to 7 days incubation so dietary history unreliable
stools negative within 6 weeks
abdo pain severe
post infection sequelae - Guillain barre, reactive arthritis

Question 15

what are the two most common species of infective campylobacter ?

Answer 15

C. jejuni

C. coli

Question 16

what are features of salmonella GE ?

Answer 16

symptom onset <48 hrs after exposure
diarrhoea <10 days
prolonged carriage of pathogen associated with gallstones
post infectious irritable bowel common

Question 17

what are the two most common types of salmonella species ?

Answer 17

S. enteritidis

S. typhimurium

Question 18

what is salmonella screened as in a lab ?

Answer 18

lactose non-fermenters

antigen O,H

Question 19

how is E.coli spread ?

Answer 19

contaminated meat

person to person

Question 20

what are features of E.coli GE ?

Answer 20

frequent bloody stools

Question 21

what toxin does E.coli release ?

Answer 21

shiga toxin

Question 22

what can the E.coli toxin cause if leaked into blood ?

Answer 22

haemolytic-uraemia syndorme

Question 23

how is haemolytic uraemia syndrome characterised ?

Answer 23

renal failure
haemolytic anaemia
thrombocytopenia

Question 24

how is haemolytic uraemic syndrome treated ?

Answer 24

supportive

Question 25

what is the pathophysiology of HUS ?

Answer 25

toxin stimulates platelet activation | micro-angiopathy results

Question 26

what are the four species of shigella ?

Answer 26

S. sonnei S. flexneri S. boydii S. dysenteriae

Question 27

what are causes of occasional food poisoning ?

Answer 27

Staph Aureus Bacillus cereus - re-fried rice Clostridium perfringens - undercooked meat

Question 28

when should Abx be used for gastroenteritis ?

Answer 28

immunocompromised severe sepsis/ invasive infection chronic illness - malignancy

Question 29

what toxins does c.dif produce ?

Answer 29

enterotoxin A | cytotoxin B

Question 30

how is c. Dif infection treated ?

Answer 30

``` metronidazole stop precipitating antibiotic oral vancomycin fidaxomicin stool transplants surgery ```

Question 31

what are the 4C antibiotics which cause c.dif infection ?

Answer 31

cephalosporins co-amoxiclav clindamycin ciprofloxacin

Question 32

how are parasites diagnosed in stool ?

Answer 32

send stool with parasites, cysts, ova

Question 33

what is the most common type of protozoa which causes diarrhoea ?

Answer 33

Giardia duodenalis

Question 34

what are features of protozoa diarrhoea ?

Answer 34

diarrhoea gas malabsorption failure to thrive

Question 35

how are protozoa transmitted ?

Answer 35

direct contact with cattle/cats/dogs/people | contaminated food/water

Question 36

how are protozoa diagnosed ?

Answer 36

cysts seen on stool microscopy | trophozoites - duodenal biopsy tightly bound to villi

Question 37

how is protozoa treated ?

Answer 37

metronidazole

Question 38

how is cryptosporidium parvum diagnosed ?

Answer 38

oocytes seen on microscopy

Question 39

how is entamoeba histolytica diagnosed ?

Answer 39

trophozoites in symptomatic patients | cysts seen in asymptomatic patients

Question 40

what is a complication of entamoeba histolytica infection

Answer 40

amoebic liver abscess

Question 41

what viruses causes diarrhoea ?

Answer 41

rotavirus norovirus adenovirus

Question 42

what is the most common viral cause of diarrhoea in children under 5

Answer 42

rotavirus

Question 43

what virus is the most common cause of diarrhoea outbreaks ?

Answer 43

norovirus

Question 44

how is norovirus diagnosed ?

Answer 44

PCR