Infection model

Question 1

An infection model

Answer 1

This model starts with the pathogen being ingested in the patient

It’s mechanism of infection then leads to the patient getting infected

Vast majority of infections look after themselves - dont need medical intervention to sort it out - self managed and we get better (outcome) - infected organism is cleared

Depending on the variation of the factors mentioned before (pathogen, patient , management etc) will determine how the infection progress’s and presents in a patient

Question 2

Pathogen

Answer 2

Can be Virus or a bacterium (both prokaryotes)

or it can be a fungus (yeast or mould)

or a parasite (protozoa or a worm) (both eukaryotes)

In Prokaryote organisms - the ribosomes are different sizes (60s compared to 80S in Eukaryotes)

Question 3

Patient

Answer 3

So many factors that influence whether or not infection occurs or not -

E.g. depends on -
Person (age, gender (UTI), social factors (sexual activity), pathological state (DMT1/2 (if don’t check foot (as lose sensation in foot) can get infection which can lead to the bone, have to cut out infected part)), physiological state)

Time - Calendar time (in January neurovirus prominent in UK, not in June - vice versa for Australia), relative time (incubation periods e.g. chicken pox) 

Place - current (started living in a different country), recent - just come back from china and now got corona virus

Question 4

Mechanism of infection

Answer 4

Depends on - contiguous spread - organism from 1 part of the organism to the other

Inoculation - if someone is inoculated from a certain virus, and someone else is, that will affect if their body allows the pathogen to take hold

Haematogenous - if they have a pathogen in the blood, or had any blood to blood contact with anyone e.g. HIV

Ingestion - eating or drinking the bacteria from certain foods - e.g. tapeworm from pork

Inhalation - respiratory pathogen - inhaling spores of a fungi

Vector - 3rd party transporting pathogen - e.g. mosquito transporting malaria

Vertical transmission - from mother to baby e.g. HIV

Question 5

Process of infection

Answer 5

Starts with a specific attachment of the pathogen to the host (e.g. influenza binds specially to receptors of the respiratory epithelium of a patient)

This then interacts with the host’s defences

Host produces Neutrophils 1) way is to release Superoxides into the surrounding environment - the hope with this is that these will attack the pathogen and destroy them.

However this can damage host tissues as well - so when you get bacterial infection you get pus formation (neutrophils) and get inflammation.

DNA of neutrophils will be discharged - DNA acts as a net and catches bacteria and then can drag it near to break it down

Question 6

Patient management

Answer 6

Take a good history, do right examination and investigations

Treatment needs to look specific (aimed at killing the microorganism in question (e.g. antibiotics) and supportive( infection prevention and vaccination)

Don’t always need specific treatment as a lot of bacteria and virus just need to “run its course”

Can also look at infection prevention - e.g. vaccinations, washing hands after consulting a patient etc

Question 7

Treatment

Answer 7

Specific - antimicrobials, surgery (drainage, debridment (removing dead or dying tissue) and dead space removal (if you’ve removed dead muscle - gap left behind cant be filled with blood or fluid)

Supportive - symptom relief, and physiological restoration