Gastroenteritis

Question 1

epidemiology of gastroenteritis

Answer 1

poor sanitation and hygiene 
travel 
contacts - human and animal 
food - time, storage, reheating, washing, importation 
acid suppression 
immunosuppression 
microbiome
genetics

Question 2

risk factors for GI infection

Answer 2

malnutrition 
closed/semi-closed communities 
exposure to contaminated food/water/travel 
winter congregating/summer floods
age<5, not breastfeeding 
elderly

Question 3

pathogen infections common with acid suppression

Answer 3

Yersinia enterocolitica, Helicobacter pylori
Clostridium difficile
Vibrio cholera, non-typhoidal Salmonella, Campylobacter jejuni, Listeria, some E.coli

Question 4

pathogen infections common with immunosuppression

Answer 4

Salmonella, Campylobacter, Shigella

Other organisms that are uncommon in immune competent

Question 5

pathogen infections common with genetic differences

Answer 5

IL8 promoter variants and severe Clostridium difficile

O blood group and Vibrio cholerae

Question 6

what is an inoculum

Answer 6

a substance introduced into the body to create or increase the body’s resistance or immunity to a disease
low infectious doses make spread of infection easier
pH affects the required dose

Question 7

scoring system for diarrhoea

Answer 7

bristol stool chart

Question 8

what is gastroenteritis

Answer 8

illness caused by eating food contaminated with micro-organisms such as bacteria, viruses and parasites
invasion tissue +/- toxin production
large volume tends tone small bowel

Question 9

symptoms of gastroenteritis

Answer 9

diarrhoea associated with blood and mucus
fever
abdominal pain
rectal tenesmus

Question 10

what is dysentery

Answer 10

a type of gastroenteritis - inflammation of intestine (especially colon)

Question 11

what bacteria is dysentery caused by

Answer 11

shigella
campylobacter
Yersinia enterocolitica - may mimic appendicitis as it may invade mesenteric nodes

Question 12

pathogens implicated in foreign travel causing gastroenteritis

Answer 12

E.Coli
Vibrio species
rotavirus

Question 13

pathogens implicated in antibiotics causing gastroenteritis

Answer 13

C diff

Question 14

pathogens implicated in day exposure causing gastroenteritis

Answer 14

rotavirus

Question 15

pathogens implicated in anal sex causing gastroenteritis

Answer 15

shigella
salmonella
campylobacter

Question 16

pathogens implicated in outbreaks causing gastroenteritis

Answer 16

norovirus

contaminated water/food - E.coli, salmonella, campylobacter

Question 17

describe bacillus cereus

Answer 17

gram positive bacillus
heat resistant spores
short incubation; 1-6 hours

Question 18

where Is bacillus cereus found

Answer 18

starchy foods - reheated rice

Question 19

describe staph aureus

Answer 19

gram positive coccus
performed toxin in food - rapid absorption
short incubation; 1-6 hours

Question 20

describe performed toxin of staph aureus

Answer 20

acts on vomiting centre in brain

vomiting/abdominal pain

Question 21

where is staph aureus found

Answer 21

foods left at room temperature - milk, meat, fish

Question 22

tests for gastroenteritis

Answer 22

stool sample
selection from normal bowel flora
enrichment for small number
genetic methods

Question 23

action of shigella toxin

Answer 23

binds to receptors four on renal cells, RBS and others

inhibits protein synthesis - causing cell death

Question 24

describe shigella toxin

Answer 24

type 1 and type 2 - 2 more potent

E.coli produces shiga-like toxins

Question 25

describe shiga-toxin producing E.coli

Answer 25

competes with normal bacterial bowel flora

Question 26

action of shiga-toxin producing E.coli

Answer 26

adheres to intestinal epithelial cells and elaborates shiga toxin enters the cell, and irreversibly inhibit protein synthesis - resulting in death of enterocytes.

Question 27

entry of shiga-toxin into the bloodstream

Answer 27

via damaged intestinal epithelium | causes death of vascular endothelial cells by inhibiting protein synthesis

Question 28

endothelial cell lysis by shiga-toxin

Answer 28

accompanied by platelet activation and aggregation, cytokine secretion, vascular contraction contributing to fibrin deposition, and clot formation within capillary lumen.

Question 29

complications of gastroenteritis

Answer 29

haemolytic uraemic syndrome (HUS) - a complication of E.Coli

Question 30

how does HUS arise

Answer 30

associated primarily with serotypes that produce shiva toxin 2 may develop after diarrhoea has stopped

Question 31

symptoms of HUS

Answer 31

``` abdominal pain fever pallor petechiae oliguria diarrhoea + blood ```

Question 32

signs of HUS

Answer 32

``` high WBC low platelets low Hb red cell fragments LDH>1.5 ```

Question 33

tests for HUS

Answer 33

``` stool culture - blood faeces U&E FBC film LFT clotting urine lactase dehydrogenase ```

Question 34

treatment for HUS

Answer 34

no antibiotics no anti-motility agents no NSAIDS

Question 35

complications of HUS

Answer 35

acute renal failure thrombocytopaenia haemolytic anaemia