Gastroenteritis

Question 1

bacilus cereus

Answer 1

1-6 hours incubation 
lasts 24 hours 
reheating starchy foods - rice
profuse vomiting 
due to heat resistant spores 
gram +ve bacilus

Question 2

staph aureus

Answer 2

1-6 hours incubation 
preformed toxin causing rapid absorption 
lasts 1-2 days 
food left at room temperature 
milk, meat, fish
vomiting abdominal pain

Question 3

campylobacter

Answer 3

16-48 hours incubation 
lasts 2-20 days 
raw poultry, raw milk
D&V may be bloody
abdomen pain, fever 
risk of Guillain Barre syndrome

Question 4

salmonella

Answer 4

outbreaks 
12-48 hours 
lasts 2-7 days 
poultry meat, raw egg, raw milk
transmitted from reptiles
D&V unlikely to be bloody 
abdomen pain, fever 
serotyped according to o antigen

Question 5

shigella

Answer 5

1-7 days incubation 
lasts 2-7 days 
contaminated food and water 
bloody diarrhoea/mucous and vomiting 
abdominal cramps, fever

Question 6

shigella toxin

Answer 6

toxin binds to receptors on renal cells, RBCs and other cells
toxin inhibits protein synthesis
toxin type 2 is more potent than type 1

Question 7

E.coli 0157

Answer 7

1-14 days incubation 
lasts 5-10 days
rare, outbreaks
cattle/beef, raw milk
bloody diarrhoea, may have vomiting 
abdomen pain 
often no fever 
risk of HUS
don't give antibiotics 
very low infectious dose 
must notify health protection unit

Question 8

verotoxin

Answer 8

shiga like toxin
binds to enterocytes causing inhibition of protein synthesis
enterocyte dies providing a route into the blood stream
death of vascular endothelial cells
clots form in small vessels
clots and verotoxin travel to kidneys eventually renal failure
bloody urine, low urine output
resulting in HUS

Question 9

HUS

Answer 9

haemolytic uraemic syndrome
antibiotics, antimotility and NSAIDs may precipitate HUS
abdomen pain, fever, pallor, petechiae (purple spots), oliguria (small urine output)

Question 10

HUS management

Answer 10

investigations 
bloody stool test
FBC, U&Es, LFT, urine samples 
lactate dehydrogenase - released from damaged cells
must notify relevant health board 
supportive treatment

Question 11

listeria

Answer 11

3-70 days incubation
lasts weeks
pregnant women, immunocompromised at risk
soft cheese, deli meats, unpasteurised milk
fever, stiff neck, confusion, vomiting
sometimes preceded by diarrhoea

Question 12

c.diff

Answer 12

after hospital antibiotics
toxin A (enterotoxin) and toxin B (cytotoxin)
watery diarrhoea
may progress to pseudomembranous colitis or bowel perforation
abdomen pain and fever

Question 13

c.diff treatment

Answer 13

non severe - metronidazole

severe - vancomycin and metrnidazole

Question 14

rotavirus

Answer 14

48 hours incubation 
lasts a week
usually children <3yrs 
most common cause of diarrhoea in kids <3
mild watery or profuse diarrhoea 
can b severe in immunocompromised child 
not bloody
can cause malabsorption

Question 15

norovirus

Answer 15

24-48 hours incubation 
lasts 1-3 days
cruise ships, wards and nursing homes, shellfish 
highly infectious 
explosive D&V
not bloody

Question 16

stool culture

Answer 16

salmonella

campylobacter

Question 17

stool toxin

Answer 17

E.coli
c.diff
shigella
staph aureus

Question 18

stool PCR

Answer 18

norovirus

rotavirus

Question 19

stool microscopy

Answer 19

parasitic infection

Question 20

treatment

Answer 20

don’t give antibiotics except c.diff

rehydration is key

Question 21

acute traveller’s diarrhoea

Answer 21

3 loose stools in 24hrs on the back of travelling
1/3rd of people have associated fever
usual causative organism is enterotoxigenic e.coli

Question 22

acute traveller’s diarrhoea management

Answer 22

stool culture
rehydration
if travelling a single dose of a ciprofloxacin can be given

Question 23

cholera

Answer 23

gram -ve bacilus 
usually from drinking faeces contaminated water 
profuse watery diarrhoea 
rice water stools 
toxin mediated

Question 24

enteric fever

Answer 24

fever, headache and abdominal discomfort
GI bleeding and perforation
typhoid caused by salmonella typhi
paratyphoid caused by s.paratyphi - less severe
SE Asia, Indian subcontinent

Question 25

enteric fever clinical findings

Answer 25

abdominal tenderness

hepatosplenomegaly

Question 26

enteric fever investigations

Answer 26

blood cultures

Question 27

enteric fever management

Answer 27

immediate isolation
if unstable give IV ceftriaxone
use oral ciprofloxacin

Question 28

amoebiasis

Answer 28

protozoa 
associated with poor sanitation 
few days - months incubation 
intermittent diarrhoea and abdominal discomfort 
upper abdominal pain
point of tenderness over right lower ribs if liver abscess 
fever, sweats
nausea
headaches

Question 29

amoebiasis investigations

Answer 29

stool microscopy
abdominal x-ray to check for toxic megacolon
CXR may sshow right hemi-diaphragm
endoscopy or biopsy

Question 30

amoebiasis management

Answer 30

metronoidazole

paramomycin

Question 31

giardiasis

Answer 31

flagellated protozoa 
duodenum and proximal jejunum 
7 days incubation 
watery malodorous diarrhoea 
bloating and flatulence 
abdominal cramps
weight loss

Question 32

giardiasis investigations

Answer 32

stool microscopy for cysts

PCR in developed countries

Question 33

diardiasis treatment

Answer 33

metronidazole

tinidazole

Question 34

helminth infections

Answer 34

parasitic infections

associated with eosinophilia

Question 35

schistomiasis - flukes

Answer 35

lake Malawi

Question 36

tape worms - cestode

Answer 36

contracted from eating undercooked meat

Question 37

gastroenteritis

Answer 37

an illness caused by eating foods contaminated with microorganisms, toxins and poisons

Question 38

dysentry

Answer 38

inflammation of the intestine, causing diarrhoea associated with blood and mucus
associated with tenesmus
commmonly caused by shigella and campylobacter

Question 39

diarrhoea

Answer 39

> 3 unformed stools in a day when the subject has taken no laxatives