Gastroenteritis

Question 1

what are the most important bug to know about?

Answer 1

campylobacter
salmonella
E.coli 0157
C.diff
listeria
shigella
norovirus
rotavirus

Question 2

describe the global impact of gastroenteritis?

Answer 2

1.4 million deaths per year

often due to poor hygiene/sanitation, commercialism, food imported, travel etc

Question 3

what are the main risk factors for GI infection?

Answer 3

malnutrition/micronutrient deficiency
closed/semi-closed community
exposure to contaminated food/water/travel
winter congregating (people stay inside in winter so closer together)
summer floods
age <5, not breast feeding
old age

Question 4

what infections are more common in acid suppression?

Answer 4

Yersinia enterocolotica
H.pylori
C. diff
vibro cholera, non-typhoidal salmonella
campylobacter

Question 5

what infections are more likely in immunosuppressed?

Answer 5

salmonella
campylobacter
shigella

Question 6

what else can increase risk of GI infection?

Answer 6

microbiome
genetics (IL8 promoter varients - C.diff, O blood group - vibro cholera)

Question 7

how does inoculum size affect GI infection?

Answer 7

median infective does is required to cause disease in 50% of people
low infectious dose makes spread easier

Question 8

what can affect required dose?

Answer 8

pH

Question 9

what is diarrhoea?

Answer 9

> 3 unformed stools per day
must not be another cause (laxatives, drug abuse etc)
stool holds shape of container
New for the patient

Question 10

what chart can measure type of diarrhoea?

Answer 10

Bristol stool chart

Question 11

what is dysentery?

Answer 11

inflammation of the intestine (mainly colon) causing diarrhoea with blood and mucus

Question 12

what are the symptoms of dysentery?

Answer 12

fever
pain
rectal tenesmus (incomplete emptying)
<2 weeks
may mimic appendicitis

Question 13

what can cause dysentery?

Answer 13

shigella

campylobacter

Question 14

what is the classic presentation of gastroenteritis?

Answer 14

diarrhoea
abdominal pain
vomiting
cholera = rice water diarrhoea
invasion of tissue +/- toxin production

Question 15

what bacteria required short incubation (1-6 hours)?

Answer 15

bacillus cereus (gram +ve):
- heat resistant spores from starchy foods (eg. reheated rice)
Staph aureus (gram +ve coccus):
- foods left at room temp
- preformed toxin in food (eg coleslaw) acts on vomiting centre in brain

Question 16

traditional vs molecular lab identification?

Answer 16

molecular = quicker, no sensitivities, broad range 
traditional = slow, cheaper, more narrow

Question 17

why must you put all relevant history (eg. travel etc) on paper request for stool sample?

Answer 17

so they test for possible atypical causes

Question 18

what is the standard test for a viral pathogen?

Answer 18

PCR

Question 19

where is shigella more common?

Answer 19

developing world
refugees
institutionalisation
military if traveled

Question 20

what disease does shigella cause?

Answer 20

dysentery

Question 21

is shigella gram +ve or gram -ve?

Answer 21

-ve

Question 22

what are the 4 groups of shigella?

Answer 22

A) S. dysenteriae (original)
B) S. flexneri
C) S. boydii
D) S. sonnei

Question 23

what does shigella do?

Answer 23

binds to receptors found on renal cells, RBCs and others
inhibit protein synthesis
causes cell death
produces 2 toxins:
- type 1
- type 2 (more potent)

Question 24

what is the connection between shigella and E.coli?

Answer 24

> 30 types of E. coli produce shiga like toxins

called STEC or verotoxin producing E. coli, or EHEC

Question 25

do you give antibiotics straight away in suspected gastroenteritis?

Answer 25

NO

Question 26

who is E.coli 0157 most common in?

Answer 26

<5s | also common in <16

Question 27

what does a culture negative bloody stool indicate?

Answer 27

toxin producing bacteria

Question 28

what bacterial factors can cause disease?

Answer 28

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

Question 29

what type of organism may mimic appendicitis?

Answer 29

Yersinia enterocolitica | as it invades mesenteric nodes

Question 30

what aspects of food prep can cause bacteria to multiply?

Answer 30

``` time temp food source moisture cross contamination of raw/cooked meat ```

Question 31

what 3 types of organism can cause gastroenteritis?

Answer 31

bacteria virus parasites

Question 32

what are important components of a history of GI infection?

Answer 32

``` diarrhoea: - frequency - blood - mucous - time course other symptoms epidemiology (travel contacts etc) food history age comorbidities medication history ```

Question 33

what is a pathotype?

Answer 33

group of symptoms and disease patterns associated with a type of bacteria

Question 34

what is the pathotype of enterotoxigenic (ETEC)?

Answer 34

produces heat labile and heat stable toxin heat stable toxin similar to cholera and Yersinia toxins travel related

Question 35

what is the pathotype of EPEC?

Answer 35

non breast-fed children can be asymptomatic non toxic, non invasive secretes own receptor into cell membrane

Question 36

what are some other types of E. coli apart from EHEC?

Answer 36

ETEC EPEC EIEC EAIC

Question 37

what is the most common cause of gastroenteritis?

Answer 37

campylobacter

Question 38

what are the classic features of a campylobacter infection?

Answer 38

``` 16-48 hrs after dodgy food pain blood fever often from poultry ```

Question 39

what bug can humans catch from reptiles?

Answer 39

salmonella

Question 40

why is salmonella more dangerous in immunosuppressed?

Answer 40

can become bacteraemia

Question 41

what is the classic presentation of salmonella?

Answer 41

12-48 hours after poultry, meat, raw egg | D&V, blood, fever

Question 42

give an example of an O antigen

Answer 42

0 0157 on E. coli 0157

Question 43

what can be used to trace a salmonella outbreak?

Answer 43

serogroups

Question 44

what is the "fridge organism"?

Answer 44

listeria

Question 45

who is listeria more likely to be invasive in (eg. meningitis)?

Answer 45

age>50 pregnant immunosuppressed (particularly T cell)

Question 46

what is the classic cause of listeria?

Answer 46

unpasteurised milk products | deli counter

Question 47

what is the classic listeria gastroenteritis presentation?

Answer 47

9-48 hours after ingesting fever, muscle aches, diarrhoea mild symptoms in pregnant women

Question 48

what is the classic presentation of invasive listeria?

Answer 48

2-6 weeks after ingestion

Question 49

how is listeria diagnosed?

Answer 49

gram +ve rod grows cell in cold (fridge temp) easier from sterile site (eg blood, CSF) but stool can be used

Question 50

does listeria monocytogenes cause listeria in humans?

Answer 50

no | humans usually have lots of neutrophils in response

Question 51

what are the 2 most important viral causes of gastroenteritis?

Answer 51

rotavirus | norovirus

Question 52

what is the most common cause of diarrhoea in children < 3 years?

Answer 52

rotavirus | lasts a week

Question 53

how is rotavirus spread?

Answer 53

person-person faecal-oral direct and indirect usually in winter

Question 54

how is rotavirus treated?

Answer 54

usually self limiting | has a vaccine (oral live attenuated)

Question 55

what is norovirus?

Answer 55

``` winter vomiting disease highly infectious (common in hospitals, cruise ships, schools) ```

Question 56

what are the symptoms of norovirus?

Answer 56

abrupt and unpredictable onset D&V sudden and explosive asymptomatic shedding (48 hrs post cessation of symptoms)

Question 57

how is norovirus treated?

Answer 57

short incubation (<24 hrs): lasts 2-4 days usually self limiting hydration is key

Question 58

how is norovirus diagnosed?

Answer 58

PCR on vomit and stool

Question 59

is all diarrhoea due to an infection?

Answer 59

no

Question 60

how can you protect yourself and patients from cross infection?

Answer 60

adhere to infection control precautions and prudent antibiotic prescribing stay off 48hrs post cessation of symptoms

Question 61

what is one health?

Answer 61

there is many ways we can be exposed to bacteria which are resistant antibiotic treatment of animals can affect the resistance profiles of bugs that are in contact with humans