Acute Suppurative Inflammation

• Inflammation is categorized into acute and chronic types
• Acute inflammation includes suppurative and non-suppurative forms
• Chronic inflammation is characterized by the predominance of lymphocytes, plasma cells, and macrophages, accompanied by fibrosis and End Arteritis Obliterans (EAO)

Suppurative Inflammation

• Also known as purulent, septic, or pyogenic inflammation
• It is associated with pus formation
• The mechanism of pus formation involves:
  • Necrosis caused by strong pyogenic bacteria such as staphylococcus aureus and streptococcus haemolyticus
  • Attraction of numerous neutrophils that die due to the bacteria's virulence
  • Presence of proteolytic enzymes primarily from dead neutrophils, leading to liquefaction of necrotic tissue and fibrin, mixing with pus cells and fluid exudate to form pus

Acute Suppurative Inflammation (Localized)

• This is caused by Staphylococcus Aureus
• The bacteria produces coagulase enzyme, leading to fibrin coagulation and deposition for localization
• Examples include:
  • Abscess
  • Furuncle (boil)
  • Carbuncle

Abscess

• This is a localized suppurative inflammation with an irregular, pus-filled cavity.
• It commonly occurs subcutaneously or in deep organs
• Early abscess development shows a central necrotic zone surrounded by acute inflammation with numerous neutrophils
• The abscess evolves through three zones:
  • Central necrotic core
  • Mid zone containing pus, formed within 48 hours within the abscess cavity
  • Peripheral zone of inflamed tissue termed the pyogenic membrane
• Course and fate of an abscess include:
  • Small abscesses can be absorbed and heal
  • Large abscesses are slowly absorbed, but their high osmotic pressure draws in water, increasing size and causing throbbing pain
• Untreated abscesses may spontaneously rupture on the skin or in hollow organs, forming an ulcer

Furuncle (Boil)

• This is a small abscess linked to a hair follicle, sebaceous gland, or sweat gland
• It is caused by staphylococci
• It is mainly found on hairy areas like the face and axilla
• Multiple neighboring boils are called furunculosis

Carbuncle

• This is an acute, localized suppurative inflammation with multiple communicating foci in the skin and subcutaneous fat, discharging pus through several openings
• It is caused by staphylococci and is common in individuals with diabetes
• It is found in areas with thick skin and subcutaneous tissue, such as the back of the neck, scalp, and buttocks

Acute Suppurative Inflammation (Diffuse)

• This is caused by streptococcus hemolyticus, producing hyaluronidase and streptokinase (fibrinolysin)
• Fibrinolysin dissolves fibrin
• Hyaluronidase dissolves the hyaluronic acid of ground substances, aiding bacterial spread
• Sites include loose connective tissue such as areolar tissue of the orbit, scrotum, and wall of the appendix
• The pus is thin and bloody, containing many sloughs (necrotic debris) due to increased necrosis
• Complications include:
  • Lymphatic spread, leading to acute lymphangitis and lymphadenitis
  • Blood spread, resulting in septicemia and pyemia

Non-Suppurative Inflammation

• Serous inflammation is characterized by excess watery fluid exudate with poor fibrin content.
• Serofibrinous inflammation involves excess fluid exudate rich in fibrin.
  • It occurs in serous membranes like the pleura, peritoneum, and pericardium
• Allergic inflammation is characterized by fluid exudate rich in eosinophils
  • It occurs in hypersensitivity cases like urticaria, bronchial asthma, allergic rhinitis, and contact dermatitis
• Catarrhal inflammation is a mild form with excess mucous secretion in mucous membranes
  • It occurs in catarrhal rhinitis
• Pseudomembranous inflammation involves a pseudomembrane of fibrin, desquamated epithelium, and inflammatory cells
  • It is caused by Diphtheria and Shigella bacilli
  • Toxemia is a common complication, along with suffocation from detached membranes (e.g., in Diphtheria)
• Hemorrhagic inflammation is marked by vascular damage and hemorrhage in the exudate
  • It occurs in meningococcemia
• Necrotizing inflammation involves extensive tissue necrosis
  • Necrotizing inflammation occurs in the oral mucosa

Chronic Inflammation

• Microscopic features include:
  • Infiltration with mononuclear cells such as macrophages, lymphocytes and plasma cells
  • Thick-walled blood vessels with End Arteritis Obliterans (EAO) of small arteries
  • Fibrosis is the surest sign of chronicity, indicating an attempt to repair tissue destruction

Types of Chronic Inflammation

• Chronic non-specific inflammation follows acute inflammation
  • It is described as "non-specific" due to multiple irritants producing the same lesion (chronic inflammatory cells, fibrosis, and EAO), irrespective of the specific cause which couldn't be identified
• Chronic specific inflammation is chronic from the start
  • Each irritant causes a specific lesion, and the irritant may be detectable within the lesion, such as Bilharzial ova in cases of Bilharziasis