Abscess and Its Complications

Abscess

• A localized area of suppurative inflammation
• Caused by pyogenic microorganisms, particularly staphylococci which produce coagulase enzymes
• Coagulase enzymes result in fibrin threads which surround and localize the area of inflammation
• Abscesses are characterized by three zones:
  • A central core of necrotic tissue that liquefies due to proteolytic enzymes released from dead polymorphs
  • An abscess cavity containing pus in the middle
  • A pyogenic membrane surrounding the cavity infiltrated with a large number of polymorphs
• If an abscess is not evacuated it will rupture at the point of least mechanical resistance
• If an abscess is evacuated, the swelling subsides, the cavity collapses, and healing occurs by granulation tissue

Complications of Abscess

• Ulcer: an area of epithelial discontinuity
• Sinus: a blind-ended tract opening to the surface that discharges pus
• Fistula: a tract with two openings (e.g., one to the surface and one to a mucous membrane)
• Chronicity: occurs if the abscess is not completely drained
• Spread of Infection
  • Lymphatics causing lymphangitis and lymphadenitis
  • Blood causing toxaemia or septicaemia
  • Septic thrombophlebitis causing pyaemia

Boil or Furuncle

• A localized suppuration in a hair follicle or sebaceous gland

Carbuncle

• A type of localized suppuration in the subcutaneous tissue, particularly in the region of the back
• Characterized by the formation of multiple loculi containing pus that open on the surface by multiple openings (sinuses)
• A serious condition that often occurs in diabetic patients

Diffuse Suppurative Inflammation: Phlegmonous Inflammation

• A diffuse form of acute inflammation that occurs in the subcutaneous tissues (cellulitis) and mucous membranes (e.g., the appendix)
• Caused by streptococcal infection which produces spreading factors (hyaluronidase and fibrinolysin) that dissolve fibrin, aiding in the spread of infection

Sequels of Acute Inflammation

• Resolution: occurs if the inflammation is mild and the individual's resistance is good
• Healing: by regeneration or organization
• Spread of Infection:
  • Direct Spread
  • Lymphatics causing lymphangitis and lymphadenitis
  • Blood causing toxaemia or septicaemia
  • Septic thrombophlebitis causing pyaemia
• Suppuration: if the infection is not suppurative from the beginning
• Chronicity: due to persistence of the causative agent

Serofibrinous Inflammation

• Exudate is rich in serous fluid and fibrin
• Occurs in serous sacs

Haemorrhagic Inflammation

• Exudate is rich in blood
• Caused by virulent organisms that damage blood vessels, as in cases of smallpox

Allergic Inflammation

• Characterized by exudation of abundant fluid containing eosinophils (e.g., urticaria)
• Caused by antigen-antibody reactions

Suppurative Inflammation

• A severe type of acute inflammation characterized by pus formation
• Can be primary or complicate other types of inflammation

Causative Organisms for Suppurative Inflammation

• Staphylococci
• Streptococci
• Gonococci
• Meningococci

Pathogenesis of Pus Formation

• Bacterial toxins cause tissue necrosis, particularly in the center
• Causative bacteria are strongly chemotactic, attracting a large umber of polymorphs
• Some polymorphs are killed in the battle against the microorganism, becoming pus cells (dead polymorphs)
• Dead polymorphs and bacteria release proteolytic enzymes that liquefy necrotic tissues, resulting in pus formation

Composition of Pus

• Living and dead microorganisms
• Living and dead polymorphs
• Liquefied necrotic tissues
• Some blood cells and globules of fat
• Inflammatory exudate

Types of Suppurative Inflammation

A- Localized Suppurative Inflammation

1- Abscess

2- Boil or Furuncle

3- Carbuncle

B- Diffuse Suppurative Inflammation

Phlegmonous Inflammation

Healing by Secondary Intention

• After evacuation of pus, the cavity becomes filled with exudate
• Formation of granulation tissue
• Regeneration of the epidermis
• Formation of scar tissue

Complications of Wound Healing

• Contracture: Shortening of collagen bundles leading to cosmetic disturbances (e.g., following healing of burns)
• Keloid: Excessive formation of collagen
• Delayed Healing:
• Secondary Infection:
• Chronic Ulcer:
• Sinus:
• Fistula:
• Inclusion Epidermoid Cyst Formation:

Healing of Serofibrinous Exudate

• The fluid is slowly absorbed
• Granulation tissue is formed and transformed into fibrous tissue
• Mesothelial cells proliferate and cover the fibrous tissue
• Sometimes fibrous tissue from the surfaces of a serous sac unites together, resulting in the formation of fibrous adhesions covered by mesothelial cells.

This quiz explores the definition, structure, and complications of abscesses, including the role of pyogenic microorganisms. Learn about the formation and potential outcomes of an abscess, such as ulcers and fistulas. Test your knowledge on this important medical concept.