An Infection Model

Question 1

Outline the Infection model

Answer 1

Pathogen + Patient

This leads to mechanism of infection

Then:
Infection

Management of Infection

Outcome of Treatment

Question 2

Expand on the pathogen part of the Infection model

Answer 2

Pathogens can be prokaryotes (bacteria), eukaryotes (fungi and parasites) or neither (viruses).

Fungi - yeast/mould

Parasite - Protozoa/Helminth

Question 3

Expand on the patient part of the Infection model

Answer 3

The patient part is broken down into person, time and place.

Person:

• age
• gender
• physiological state
• pathological state
• social factors

Time:

• calendar time (seasons in the year)
• relative time (incubation period -useful for making a diagnosis for the disease)

Place:

• current
• recent

Question 4

Expand on the “mechanism of infection” part of the Infection model

Answer 4

contiguous (direct) spread
inoculation
haematogenous
ingestion
inhalation
vector
vertical transmission

Question 5

Expand on the “infection” part of the Infection model

Answer 5

Infection -> attachment -> toxin production/interaction with host defences (both lead to host damage) and interaction with host defences leads to inflammation before the host is damaged

Question 6

Expand on the “management” part of the Infection model

Answer 6

History
Examination
Investigations
Treatment
Infection prevention

The first three are how you make the diagnosis -> where is the infection?/what is the infection?

The treatment can be specific (blood culture sent to lab) or supportive (antibiotics, pain relief while waiting for blood results)

Infection prevention depends of whether the patient is in the hospital and community.

Question 7

Treatment is carried out during the management stage. Outline the two main parts of treatment

Answer 7

Treatment can be specific or supportive.

Specific treatment includes:
- Antimicrobials
- Surgery 
   = drainage
   = debridement (removal or damaged tissue or foreign objects from a wound)
   = dead space removal

Supportive treatment includes:

• Symptom relief
• Physiological restoration

Question 8

What is dead space and why does it need to be removed?

Answer 8

It is a hole resulting from drainage and debridement.

This dead space gives opportunity for fluid to build up and microorganisms and can cause infection, thus we must prevent dead space from forming and remove it.

Question 9

What is debridement?

Answer 9

The removal of damaged tissue or foreign objects from a wound

Question 10

Infection prevention is carried out during the management stage. Expand on this sub-stage.

Answer 10

This sub-stage is divided into the hospital and community.

The idea is that we prevent infection transmission to:
• other patients
• staff
• other contacts

Question 11

The outcome stage is the last stage of the infection model. Explain it.

Answer 11

This stage varies depending on the infection.

Can range from a fully cure or death.

Individual could be disabled as a result of it or have a chronic infection.

Question 12

Are there exceptions to the model?

Answer 12

Yes!

The exceptions are important