T3: Abscess

Question 1

What is an abscess?

Answer 1

An Abscess is a collection of pus; it is a complication of acute inflammation. Normally in acute inflammation, we get inflammation. If there is too much exudate, abscess is formed. Suppuration - collection or generation of pus.

Question 2

What are the 3 main stages of acute inflammation?

Answer 2

• Vasoconstriction followed by dilation and increased vascular permeability
  
  • Extravasation of white blood cells - this is an organised process. There is margination, adhesion and transmigration and chemotaxis. Diapedesis is the term for the cells moving through the gaps in the capillary.
  • Phagocytosis to remove the noxious substance.

Question 3

What is margination of neutrophils?

Answer 3

The neutrophils adhere to the endothelium.

Question 4

How are pathogens opsonised?

Answer 4

Phagocytosis is the last stage. Its starts with opsonisation of the particles by IgG or C3. this allows identification. Then the phagocyte engulfs the tissue killing it with toxic intracytoplasmic process (reactive oxygen species and myeloperoxidase which makes bleach).

Question 5

What are clinical signs of acute inflammation?

Answer 5

Rubor, Calor, Dolor, Tumour and Functio laesa.

Question 6

Explain the clinical signs of acute inflammation.

Answer 6

→ Rubor (redness) - caused by vasodilation
→ Calor (heat) - caused by hyperaemia (increased blood flow) and systemic increase in temperature due to cytokines
→ Tumor (swelling) - exudate has a mechanical effect to swell and stop the part of the body moving when injured. This result s in localised oedema.
→ Dolor (pain) - caused by cytokines (bradykinin, serotonin, prostaglandins) and physical pressure on the exudate pushing against nerves
→ Functio laesa (loss of function) - combination of the pain that stops you wanting to do things and swelling

Question 7

What is the pathology of suppuration?

Answer 7

Suppuration - the formation of pus. Pus comprises of living and dead neutrophils, cell/tissue debris and bacteria (in formed by infection). It is yellow-green colour). Usually formed by bacteria. Pyogenic bacteria are pus generating bacteria. Suppuration forms an abscess. It can be in an organ, soft tissue and skin. Abscesses are not accessible to antibiotics, since a collection of dead things and neutrophils. This requires a surgeon. If untreated it can cause uncontrolled infection around the body (septicaemia).

Question 8

Give examples of pyogenic bacteria.

Answer 8

There are some bacteria that are pus forming by nature such as Staphylococcus, Streptococcus and Gonococcus.

Question 9

How are abscess managed?

Answer 9

• Incision and drainage
  
  • Surgical excision
  • Management of the residual cavity

You cannot use medical therapy, the pus must be drained.

You need to send a sample to the microbiology lab. There may be still circulating infection. Put the tissue in a little saline to stop in drying out. Do not put in it formalin - as it kills the organisms.

When you go to the microbiology lab we spread the material on an agape plate and incubate tit for 24-28 hours. When bacterial then grows it can be seen under the microscope.

We can take discs of antibiotics and drop them onto the plate and see which bacteria are affected by the antibiotic - culture and sensitive test.

Question 10

What is granulation tissue?

Answer 10

Granulation is a special healing tissue made up of:

- Capillaries 
- Fibroblasts that allow tissue to produce collagen 
- Inflammatory cells 

Granulation tissue is induced anywhere in the body where there has been acute inflammation and damage. E.g. in the heart after an MI, it becomes less vascular and more collagenous.

Question 11

What is an empyema?

Answer 11

Empyema - collection of pus in the chest well. May be a complication of surgery, or in viral pneumonia.