Abscess Flashcards
What is the usual result of acute inflammation?
It usually resolves entirely
What happens if there is excess exudate in acute inflammation?
this leads to suppuration
this is the process of pus formation, leading to abscess formation
What is the definition of an abscess?
a collection of pus that is a complication of acute inflammation
Why does acute inflammation happen?
What usually causes it?
it is the initial tissue reaction to injury
it is caused by physical, chemical, infectious methods
it can also be immune mediated
What are the 5 signs of acute inflammation?
- redness (rubor)
- heat (calor)
- swelling (tumor)
- pain (dolor)
- loss of function
What are the 3 stages associated with acute inflammation?
- vascular changes
- extravasation of white blood cells
- phagocytosis
What is involved in the vascular changes of acute inflammation?
There is initial vasoconstriction
This is followed by dilation and increased vascular permeability
What is involved in extravasation of white blood cells?
It is an organised sequential process of:
- margination
- adhesion
- transmigration
- chemotaxis
What is involved in phagocytosis?
Removing the substance that is causing damage in the first place, as well as damaged tissue
What happens after the vessels have undergone vasodilation?
Serum, proteins and cells pass from inside to outside the vessel
The fluid that leaves the blood vessel is an exudate
What is margination?
the adhesion of white blood cells to the walls of damaged blood vessels
What is transmigration?
the passage of blood cells through blood vessel walls
What is chemotaxis?
movement of a cell in response to a gradient of increasing or decreasing concentration of a particular substance
What are the three stages in phagocytosis?
- opsonisation of particles by IgG or C3
- engulfment by macrophages
- killing
How do phagocytes kill invading pathogens?
- reactive oxygen species
2. myeloperoxidase (makes HOCl)
What causes redness (rubor)?
vasodilation
this increases blood flow to the area
What causes heat (calor)?
hyperaemia - increased blood flow going through the tissue
cytokines also increase the temperature
What causes swelling (tumor)?
Localised oedema
The exudate also has a mechanical effect to swell
What causes pain (dolor)?
Local cytokines (bradykinin, serotonin, prostaglandins)
Physical pressure of the exudate pushing against nerves
What causes loss of function?
Pain and swelling
The pain then stops the patient from wanting to do things
What is suppuration?
the formation of pus
What is contained within pus?
- living and dead neutrophils
- cell & tissue debris
- bacteria
What type of bacteria usually cause suppuration?
What colour is pus?
Pyogenic bacteria
It is yellow-green in colour
What does suppuration form?
An abscess
This is a collection of pus in the body
Where may an abscess form?
in an organ, soft tissue (such as fat) and skin
What antibiotics can be used to treat abscesses?
Abscesses are not accessible to antibiotics
What happens if an abscess is untreated?
it can cause an uncontrolled infection around the body
this is septicaemia
If there is pain in the right iliac fossa, what does this indicate?
there is inflammation/swelling in the appendix
What is empyema?
a condition where pockets of pus collect inside a body cavity
most commonly in the pleural space
What usually causes empyema?
- complication of surgery
- spontaneous
- can result from pneumonia, where fluid moves between the lung and chest wall
What would empyema look like on an X-ray?
Lung is expanded on the normal side
Lung is collapsed and pushed forwards on the infected side
What is the technique used to treat an abscess?
incision and drainage
Why is general anaesthetic used when treating an abscess?
local anaesthetic doesn’t work as well around the abscess
What is necrotising fasciitis?
an infection that results in death of parts of the body’s soft tissue
What is the danger of necrotising fasciitis?
it is a very serious infection that needs to be treated immediately
What are the aims of treating an abscess?
- to remove all the infected material
2. to encourage healing
Why can an abscess not be treated with medical therapy?
the pus needs to be drained out of the abscess
What is involved in microbiological investigation of abscess?
- send a sample to the microbiology lab - this can be a swab, pus or tissue
- send in a sterile jar
- put tissue in saline to stop it drying out
What should abscess tissue not be put in?
Formalin
This kills the organisms
What is done to the sample once it reaches the microbiology lab?
- spread the material on agar
2. incubate at 37 degrees to culture the bacteria
How can the microorganism be identified?
From the growth pattern on the agar gel
What is the culture and sensitivity test?
From the suppression of growth around an antibiotic disc, you can work out what antibiotics the organism is sensitive and resistant to
What is granulation tissue?
new connective tissue and microscopic blood vessels that form on the surface of wound during the healing process
What is contained within granulation tissue?
Capillaries, oedema, white cells and fibroblasts
What are the benefits of scar formation?
it prevents infection
it protects against mechanical trauma
What is the drawback of scar formation?
it stops regeneration, which can lead to a permanent scar
