Food poisoning

Question 1

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

Answer 1

Type 5

Question 2

What is food poisoning?

Answer 2

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

Question 3

What sorts of pathogens can cause food poisoning?

Answer 3

Bacteria, viruses and parasites

Question 4

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

Answer 4

If the bacteria/pathogen has invaded the bowel wall

Question 5

What GI symptoms are usually present with food poisoning?

Answer 5

Abdominal pain, vomiting, diarrhoea

Question 6

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

Answer 6

Hep A and toxoplasma

Question 7

Which bacteria is the commonest cause of food poisoning?

Answer 7

Campylobacter

Question 8

Which bacteria causes outbreaks?

Answer 8

Salmonella

Question 9

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

Answer 9

E. coli 0157

Question 10

Where do most cases of food poisoning occur?

Answer 10

At home

Question 11

What are relevant aspects of a patient’s history?

Answer 11

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

Question 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?

Answer 12

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

Question 13

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

Answer 13

Salmonella
CI perfringens
There is diarrhoea which is often bloody

Question 14

Which pathogens have a long intubation period of 2-14 days?

What symptoms do they cause?

Answer 14

Campylobacter
E.coli 0157
Diarrhoea which is often bloody

Question 15

Where does bacillus cereus live?

Answer 15

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.

Question 16

What is the incubation period of campylobacter?

Answer 16

16-48 hours

Question 17

What food is campylobacter found in?

Answer 17

Poultry and raw milk

Question 18

Is campylobacter invasive?

What are the main symptoms?

Answer 18

Yes it is invasive.

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

Question 19

How should a patient with campylobacter infection be managed?

Answer 19

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.

Question 20

What is the incubation period for salmonella enteritidis?

Answer 20

12-48 hours

Question 21

What foods are salmonella enteritidis found in?

Answer 21

Poultry, meat and raw egg

Question 22

How does salmonella enteritidis cause symptoms?

What symptoms does it cause?

Answer 22

By releasing toxins and invading the gut wall

It causes diarrhoea and vomiting, blood and fever

Question 23

How should salmonella enteriditis be managed?

Answer 23

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

Question 24

How is salmonella enteriditis prevented?

Answer 24

Food hygeine
Vaccination of hens
Animal hygeine

Question 25

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

Answer 25

Reptiles

Question 26

How is salmonella typed?

Answer 26

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

Question 27

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

Answer 27

B, C and D

Question 28

When should E.coli 0157 be suspected?

Answer 28

With bloody diarrhoea or blood per rectum

Question 29

How is E.coli 0157 contracted?

Answer 29

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

Question 30

Does E coli 0157 have outbreak potential?

Answer 30

Yes

Question 31

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

Answer 31

Verotoxin (VTEC)

Question 32

What is the incubation period of E.coli 0157?

Answer 32

1-14 days

Question 33

What are the symptoms caused by E.coli 0157?

Answer 33

Bloody diarrhoea Haemorrhagic colitis Haemolytic Uraemic Syndrome

Question 34

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

Answer 34

Excretion of the pathogen declines

Question 35

How does haemolytic uraemic syndrome present?

Answer 35

``` 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 ```

Question 36

What ages are affected most by HUS?

Answer 36

Under 16 years old

Question 37

Describe the blood components in HUS

Answer 37

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

Question 38

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

Answer 38

Yes- there was an outbreak of 0104

Question 39

What does verotoxin do? | What is its effect?

Answer 39

``` 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

Question 40

What investigations are done when HUS is suspected?

Answer 40

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

Question 41

What complications can patients with HUC develop?

Answer 41

Acute renal failure Thrombocytopaenia (decrease in platelets) Haemolytic anaemia

Question 42

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

Answer 42

Antibiotics- may precipitate HUC Anti-motility agents NSAIDs

Question 43

How is E.coli diagnosed microbiologically?

Answer 43

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

Question 44

When should E coli be suspected ?

Answer 44

``` 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 ```

Question 45

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

Answer 45

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