Chapter 17- Eye & Skin Infections POWERPOINT

Overview of Skin and Eye Infections

Skin Structure and Function

  • Largest organ: Skin acts as the first defense against pathogens.

  • Layers: Epidermis (outer layer), Dermis (middle layer with connective tissues), Subcutaneous (inner layer with fat).

  • Defense mechanisms: Melanin, perspiration (acidic pH, lysozyme), sebum (protective oils).

Skin Microbiome

  • Normal microbiota help in protection and are influenced by environmental and physiological factors.

  • Major skin residents include Staphylococcus, Pseudomonas, and Malassezia species.

Skin Lesions and Rashes

  • Primary lesions: Vesicle, bulla, macule, papule, pustule, cyst, maculopapular.

  • Secondary lesions: Crust, scale, purpura, petechiae, ulcer.

Viral Skin Infections

  • Chickenpox (varicella-zoster): Causes itchy vesicular rash, can reactivate as shingles.

  • Measles and Rubella: Highly contagious, can lead to severe complications.

  • Fifth disease (Parvovirus B19) and Roseola (HHV-6) are common childhood infections.

Bacterial Skin Infections

  • Staphylococcus aureus: Causes impetigo, cellulitis, and MRSA.

  • Streptococcus pyogenes: Causes impetigo and necrotizing fasciitis.

  • Pseudomonas aeruginosa: Opportunistic infections, especially in burn patients.

Fungal Skin Infections

  • Tinea (ringworm): Caused by dermatophytes, affecting skin, hair, and nails.

  • Cutaneous candidiasis: Caused by Candida albicans, common in moist areas.

Eye Infections

  • Conjunctivitis (pink eye): Inflammation of the conjunctiva; caused by bacteria or viruses.

  • Keratitis: Inflammation of the cornea; serious and can be bacterial, viral, or fungal.

  • Trachoma: Chronic conjunctivitis caused by Chlamydia trachomatis; leads to blindness.

Disease Snapshot - Common Infections

  • Chickenpox and Shingles: Varicella-zoster virus; transmitted by respiratory droplets.

  • Measles and Rubella: Highly contagious viral diseases; preventable by vaccines.

  • Bacterial conjunctivitis: Caused by various bacteria, marked by pus-like discharge.

  • Fungal keratitis: Risk increases with contact lens use; treated with antifungals.