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Flashcards in Food poisoning Deck (45):
1

What number and above on the bristol stool chart signifies diarrhoea?

Type 5

2

What is food poisoning?

Illness caused by eating food contaminated with micro-organisms, toxins, poisons etc

3

What sorts of pathogens can cause food poisoning?

Bacteria, viruses and parasites

4

Why might there be blood in the stool in food poisoning?

If the bacteria/pathogen has invaded the bowel wall

5

What GI symptoms are usually present with food poisoning?

Abdominal pain, vomiting, diarrhoea

6

Name a protozoa and a virus which are transmitted via food but do not cause diarrhoea

Hep A and toxoplasma

7

Which bacteria is the commonest cause of food poisoning?

Campylobacter

8

Which bacteria causes outbreaks?

Salmonella

9

Name a bacteria which is rare but causes significant morbidity and outbreaks

E. coli 0157

10

Where do most cases of food poisoning occur?

At home

11

What are relevant aspects of a patient's history?

Diarrhoea- is there blood?
History- travel, functions, contacts
Suspect food
Anyone else suffering?
Time from ingestion of suspect food
Age of patient- children have a different risk for different pathogens than adults
Underlying medical problems

12

Which pathogens have a short incubation (time from ingestion to onset of symptoms) period of 1-6 hours?
Why is this time short?
What symptoms are there?

Staph aureus
Bacillus cereus
There is a preformed toxin which is rapidly absorbed. This acts on the vomiting centre in the brain.
There is vomiting and severe abdominal pain

13

Which pathogens have a medium intubation period of 12-48 hours?
What symptoms do they cause?

Salmonella
CI perfringens
There is diarrhoea which is often bloody

14

Which pathogens have a long intubation period of 2-14 days?
What symptoms do they cause?

Campylobacter
E.coli 0157
Diarrhoea which is often bloody

15

Where does bacillus cereus live?

Cereus = cereal
it lives in rice and cereal crops
used to be called chinese restaurant syndrome, as they would leave rice out overnight at room temp and fry it the next day, which did not remove the toxins.

16

What is the incubation period of campylobacter?

16-48 hours

17

What food is campylobacter found in?

Poultry and raw milk

18

Is campylobacter invasive?
What are the main symptoms?

Yes it is invasive.
The main symptoms are pain, blood in the stool (30%) and fever.

19

How should a patient with campylobacter infection be managed?

Rule of thumb is don't use antibiotics unless you have to, i.e. if the patient has comorbid factors.
If antibiotics are used: ciprofloxacin/erythromycin
Any person with diarrhoea should be in a single room but not so vital for campylobacter because there is less chance of person to person spread.

20

What is the incubation period for salmonella enteritidis?

12-48 hours

21

What foods are salmonella enteritidis found in?

Poultry, meat and raw egg

22

How does salmonella enteritidis cause symptoms?
What symptoms does it cause?

By releasing toxins and invading the gut wall
It causes diarrhoea and vomiting, blood and fever

23

How should salmonella enteriditis be managed?

If antibiotics are required (i.e. if the patient has comorbid factors), ciprofloxacin should be used.

24

How is salmonella enteriditis prevented?

Food hygeine
Vaccination of hens
Animal hygeine

25

What type of animals that may be kept as pets can carry another type of salmonella?

Reptiles

26

How is salmonella typed?

1. By serogrouping by different antigens on the body (e.g. the O antigen).
This is done by slide agglutination: the antigen agglutinates with the corresponding antibody
2. Serotyping- the serogroups are further divided by looking at the antigens on the tail of the bacterium.
E.g. salmonella enteriditis: eggs, poultry
sal. typhimurium- cooked ham

27

What are the commonest groups of salmonella in Tayside, in the O antigen group?

B, C and D

28

When should E.coli 0157 be suspected?

With bloody diarrhoea or blood per rectum

29

How is E.coli 0157 contracted?

Beef, raw water/milk
Person to person contact- both direct and indirect
Animal contact

30

Does E coli 0157 have outbreak potential?

Yes

31

Which toxin does E.coli 0157 produce that causes symptoms?

Verotoxin (VTEC)

32

What is the incubation period of E.coli 0157?

1-14 days

33

What are the symptoms caused by E.coli 0157?

Bloody diarrhoea
Haemorrhagic colitis
Haemolytic Uraemic Syndrome

34

Why should stool samples be sent as soon as possible when E.coli 0157 is suspected?

Excretion of the pathogen declines

35

How does haemolytic uraemic syndrome present?

Abdominal pain
Fever
Pallor
petechiae (small red or purple dot on skin caused by haemorrhage)
oliguria- low output of urine
Bloody diarrhoea in 90% of cases

36

What ages are affected most by HUS?

Under 16 years old

37

Describe the blood components in HUS

High white cells
Low haemaglobin
Low platelets
High red cell fragments
LDH > 1.5 x normal
May develop after diarrhoea has stopped

38

Can verotoxin be produced by other E coli strains as well as E.coli 0157?

Yes- there was an outbreak of 0104

39

What does verotoxin do?
What is its effect?

It binds to receptors found on renal cells, RBCs and others.
Inhibit protein synthesis
Cell swelling
Intravascular coagulation
Platelet aggregation
Mechanical damage RBC

Causes cell death
Gives rise to HUS

40

What investigations are done when HUS is suspected?

Stool culture samples of all patients with bloody faeces
U & E
FBC
LFT
clotting
urine
lactate dehyrdrogenase

41

What complications can patients with HUC develop?

Acute renal failure
Thrombocytopaenia (decrease in platelets)
Haemolytic anaemia

42

What should patients with suspected HUC/HUC not be given?

Antibiotics- may precipitate HUC
Anti-motility agents
NSAIDs

43

How is E.coli diagnosed microbiologically?

Selective culture for E.coli
Sorbitol non fermenter
E coli isolated
Check if it has 0157 antigen

If there is bloody stool but negative culture:
Send for more sensitive tests
Verotoxin gene may be detected
It is typed to trace the source

44

When should E coli be suspected ?

Infectious bloody diarrhoea
Acute onset non-bloody diarrhoea with no other explanation and likely exposure to 0157:
Contact with farm animals
Private drinking water
Burgers
Unpasteurised dairy product
Contact with confirmed/susepcted case

45

When must be health protection unit be notified?
What do they do?

Confirmed cases of HUS or 0157
There is contact tracing and investigation
Environmental Health inspect food premises

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