Gastroenteritis

Question 1

what are common causative organisms of gastroenteritis

Answer 1

campylobacter (commonest)
salmonella
(outbreaks)
E coli 0157

C.diff, listeria, shigella, norovirus, rotavirus

Question 2

how is gastritis mostly treated

Answer 2

supportive treatment- no antibiotics

Question 3

how is it spread

Answer 3

faecal- oral transmission

Question 4

what are the GI infection risk factors

Answer 4

malnutrition (micro nutrient deficiency), 
closed/ semi closed, 
exposure to contaminated food/ water/ travel,
 winter congregating,
 age <5, or elderly, 
acid suppression,
immunosupression,
microbiome,
genetics

Question 5

what organism is more common in acid suppression

Answer 5

C. diff

Question 6

what bacterial factors allow them to infect patients

Answer 6

adherence/attachment to the gastrointestinal mucosa,
cellular invasion,
production of exotoxins,
changes in epithelial cell physiology,
loss of brush border digestive enzymes, and/or cell death,
increased intestinal motility, net fluid secretion, influx of inflammatory cells, and/or intestinal hemorrhage

Question 7

what is the inoculum size

Answer 7

median infecting dose required to cause disease in 50%- low inoculum means easier spread

Question 8

what affects inoculum size

Answer 8

pH and gastric mobility

Question 9

what is diarrhoea

Answer 9

> 3 unformed stools a day (a departure from normal bowl habit) with no other cause (laxatives, drig abuse, stimulants) where the stool holds the shape of the container

Question 10

what is dysnetry

Answer 10

gastroenteritis

Question 11

what is gastroenteritis

Answer 11

An illness caused by eating food contaminated with micro-organisms, toxins, poisons etc
- inflammation of the intestine, particularly the colon, causing diarrhea associated with blood and mucus

Question 12

what are the symptoms of gastroenteritis

Answer 12

diarrhoea with blood and mucus, fever, abdominal pain, rectal tenesmus (sense of incomplete defecation), frequent bowl movements

Question 13

what is the acute duration of gastroenteritis

Answer 13

<2 weeks

Question 14

how might yersinia enterocolitica mimic appendicitis

Answer 14

as it may envade mesenteric nodes

Question 15

how can food cause gastroenteritis

Answer 15

cross contamination, waiting too long to eat, inadequate heating and cooling, contaminated environment, poor personal hygiene

Question 16

why most spores be considered in cooking

Answer 16

as can survive the adverse conditions of many cooking methods

Question 17

what does a large volume of bowl movements tent to mean

Answer 17

it comes from the small bowel- small volume= large bowel

Question 18

describe the diarrhoea produced by cholera

Answer 18

large volume of rice water diarrhoea

Question 19

what are factors that could mean a likelihood of gastroenteritis

Answer 19

foreign travel, recent camping or antibiotics, exposure to daycare or raw sea food, anal receptive sex, HIC positive status, outbreaks

Question 20

why does gastroenteritis a very short incubation period

Answer 20

as pathogens pre form toxins

Question 21

what organism cause gastroenteritis with an incubation period of 1-6 hours

Answer 21

bacillus cereus (gram +ve bacillus) found in starchy foods

staph aureus (pre formed toxin in food which acts on vomiting centre in the brain) gram +ve coccus- foods left at room temp

Question 22

how does the lab identify the causative organism

Answer 22

traditional methods (culture), molecular methods (e.g. microarrays), viral pathogen PCR

Question 23

why must you put details of the patients history on a stool sample

Answer 23

so lab can look for more specific causes

Question 24

where is shigella common

Answer 24

refugees/ institutionalisation/ military

Question 25

what does shiga toxin do

Answer 25

binds to receptors in renal cells, RBC and others- inhibits protein synthesis and causes cell death

Question 26

what toxins does shigella produce

Answer 26

type 1 and type 2 (more potent)

Question 27

what can produce shiga like toxins

Answer 27

other bacteria

Question 28

what is a STEC

Answer 28

shiga like toxin producing e coli

Question 29

what ecoli should be considered in association with shiga like toxin

Answer 29

e coli 0157

Question 30

how can shiga toxin e coli cause blood clotting

Answer 30

Shiga toxins can then enter the bloodstream via damaged intestinal epithelium and cause the death of vascular endothelial cells by the same mechanism as absorptive enterocytes. Endothelial cell lysis is accompanied by platelet activation and aggregation, cytokine secretion, vascular constriction contributing to fibrin deposition, and clot formation within the capillary lumen.

Question 31

how can STEC cause HUS and what is it

Answer 31

haemolytic uraemic syndrome- toxins in blood are carried to the kidneys causing hematuria and renal failure

Question 32

when should you suspect E coli 0157

Answer 32

bloody diarrhoea, food, person to person, very low infectious dose, children and elderly at highest risk of complications, haemorrhagic colitis

Question 33

what is VTEC

Answer 33

verotoxin producing e coli

Question 34

what is the presentation of HUS

Answer 34

Abdo pain, fever, pallor, petechiae, oliguria bloody diarrhoea in 90% of cases 85% of HUS cases are under 16 years old ``` High white cells Low platelets Low HB Red cell fragments LDH>1.5 x normal May develop after diarrhoea stopped ```

Question 35

how can HUS develop after diarrhoea stops

Answer 35

Toxin related not due to active proliferation of pathogen

Question 36

what investigations should be done into HUS

Answer 36

stool culture samples, U&E, FBC, film LFT, clotting, urine

Question 37

how should HUS NOT be treated

Answer 37

NO antibiotics: may precipitate HUS NO anti-motility agents NO NSAIDS ANTIBIOTICS MAKE TOXINS WORSE- DONT GIVE UNTIL YOU KNOW ITS BENEFICIAL

Question 38

what antibiotics should be given in gastroenteritis

Answer 38

NONE

Question 39

where should all cases be reported to

Answer 39

health protection unit

Question 40

what are the different pathotypes of e.coli

Answer 40

entero: -toxigenic produces heat stable/ labile toxin -pathogenic Synthesises, secretes and inserts its own reseptor into cell membranes, may be asymptomatic -invasive watery diarrhoea -aggregative travellers diarrhoea

Question 41

what is the most common caustive pathogen of diarrhoea

Answer 41

campylobacter

Question 42

what is the incubation period of campylobacter

Answer 42

16-48 hrs

Question 43

where is campylobacter found

Answer 43

food: poultry, raw milk

Question 44

what antibiotics are used against campylobacter

Answer 44

macrolide

Question 45

what is treating e coli 0157 with antibiotics a possible risk factor of

Answer 45

HUS- haemolytic uraemic syndrome

Question 46

name a subspecies of campylobacter

Answer 46

jejuni

Question 47

what are the symptoms of campylobacter infection

Answer 47

diarrhoea, pain, blood (30%), fever

Question 48

what does campylobacter look like

Answer 48

corkscrew appearance with bipolar flagella

Question 49

what pathogen is found on lizards

Answer 49

salmonella- why HIV, immunosuppressed, sickle cell, malignancy ask to not have reptiles

Question 50

what organisms cause outbreaks of gastroenteritis

Answer 50

salmonella, E coli 0157

Question 51

what is the incubation period of salmonella

Answer 51

12-48 hr

Question 52

where is salmonella found

Answer 52

poultry, meat, raw egg, animal gut

Question 53

how goes salmonella infect

Answer 53

toxin and envasion

Question 54

what are the symptoms of salmonella infection

Answer 54

D&V, blood, fever

Question 55

what does salmonella's structure contain

Answer 55

flagellum, lipopolysaccharide, O and H antigens

Question 56

what is the use of serogrouping salmonella

Answer 56

pinpoint source of infection, detecting outbreaks/ contact tracing

Question 57

why is listeria monoctogenes known as the fridge organism

Answer 57

an in unpasteurised milk products, deli counter

Question 58

what are the symptoms of gastroenteritis caused by listeria monocytogenes

Answer 58

9-48 hours incubation period fever, muscle aches, diarrhoea

Question 59

what are the symptoms of an invasive listeria infection

Answer 59

2-6 weeks later in immunosuppressed meningitis/ bacteraemia (why you avoid unpasteurised food when pregnant)

Question 60

what type of bacteria is listeria

Answer 60

gram +ve rod

Question 61

how is listeria spread

Answer 61

food borne transmission, mother to child

Question 62

name two viruses that cause viral gastroenteritis

Answer 62

rotavirus, norovirus, adenovirus, astrovirus

Question 63

how is viral gastroenteritis diagnosed

Answer 63

stool sample, PCR assay, immunoassay, antigen detection, serology

Question 64

how is rotavirus spread

Answer 64

person to person, faecal oral, usually in winter

Question 65

what are the symptoms of rotavirus gastroenteritis

Answer 65

mild to profuse water diarrhoea, shock, fever, vomiting, self limitng

Question 66

what is the most common cause of gastroenteritis in children under 3 years

Answer 66

rotavirus

Question 67

what does rotavirus affect in the bowel

Answer 67

absorption and secretion

Question 68

how big is the infectious dose of rotavirus

Answer 68

low

Question 69

how is rota virus managed

Answer 69

hydration, vaccine

Question 70

describe the rotavirus vaccine

Answer 70

oral, live attenuated

Question 71

what is the winter vomiting bug

Answer 71

norovirus

Question 72

how is norovirus spread

Answer 72

faecal oral, droplet, person to person, contaminated food/water

Question 73

what is the reservoir of norovirus

Answer 73

the community circulation

Question 74

what can happen 48 hrs after cessation of symptoms in norovirus

Answer 74

asymptomatic shedding

Question 75

what is the incubation period of norovirus

Answer 75

less than 24 hours

Question 76

how long does norovirus usually last

Answer 76

2-4 days

Question 77

how is norovirus treated

Answer 77

hydration- usually self limiting