Infection of the Skin

• Skin

  • Has normal flora
  • Low pH
  • Has lysozyme and sebum
• Important parts & layers of the skin

  • Epidermis
  • Dermis
  • Subcutaneous layer
  • Sebaceous (oil) gland
  • Hair follicle
• Common Skin Infections

  • Dermatitis
  • Folliculitis
  • Stye
  • Furuncle
  • Carbuncle
  • Macule
  • Papule
  • Vesicle
  • Pustule
• Dermatitis - inflammation of the skin
• Folliculitis - inflammation of the hair follicle
• Stye - inflammation of the sebaceous glands at the eyelash
• Furuncle - boil; pus-producing localized infection of the skin, usually from folliculitis
• Carbuncle - deep seated pus-producing (pyogenic) infection of the skin; usually arising from the coalescence of furuncles
• Macule - surface lesion (usually discolored) that is neither raised nor depressed
• Papule - firm and raised surface lesion
• Vesicle - blister (fluid filled)
• Pustule - pus-filled surface lesion
• Viral Skin Infections

  • Chickenpox and Schingles
  • Rubella (German Measles)
  • Rubeola (Hard Measles)
  • Monkeypox
  • Smallpox
  • Warts
• Varicella (chickenpox)

  • Varicella-zoster virus (a herpes virus)
  • Double-stranded DNA virus, enveloped
  • Transmission: Direct contact, droplet, airborne
  • Fever and skin rash; Vesicles forming (mucous membrane)
  • Self-limiting, vaccine-preventable
  • May develop to Reye`s syndrome – severe encephalomyelitis with liver damage
  • Latency- does not leave the body; stays in nerve root ganglia to remain in a dormant stage
• Herpes Zoster (Shingles)

  • Reactivation due to immunosuppression (common after 50 years old)
  • Common at the torso/abdominal area – nerves known as dermatones
• Herpes Zoster (Shingles)

  • Reactivation due to immunosuppression (common after 50 years old)
  • Common at the torso/abdominal area – nerves known as dermatones
• Rubeola (Hard Measles)

  • Rubeola
  • Single-stranded RNA virus; Enveloped
  • Fever, conjunctivitis, cough, photosensitivity,
  • Koplik spots in the mouth and red blotchy skin
  • Transmission: Airborne and direct contact to secretions
• Rubella (German Measles)

  • Rubella virus
  • RNA virus
  • Transmission: Droplet and direct contact with secretions
  • Fever and flat, pink rashes; Starts from face – neck – truck - extremities
• Monkeypox

  • Rare
  • Monkeypox virus
  • Transmission: animal bite or direct contact with animal secretions and infected person
• Smallpox

  • Variola minor and variola major (20-40% fatal)
  • Double-stranded DNA
  • Systemic infection- fever, malaise, headache, severe backache, sometimes vomiting and abdominal pain
  • Transmission: Droplet
  • Biological warfare and bioterrorism
• Warts

  • HPV (human papillomaviruses)
  • Non-enveloped DNA virus
  • Have many types
  • Most are cancerous
  • Transmission: direct contact, genital warts are STDs
• Warts - mostly skin-or dark-colored growths on the skin caused by a virus, the Human Papillomavirus
• Types of Warts

  • Common Warts
  • Flat Warts
  • Plantar Warts
  • Filiform Warts
  • Genital (Venereal) Warts
• Bacterial Skin Infections

  • Acne
  • Anthrax
  • Gas Gangrene
  • Leprosy
• Staphylococcal infections:

  • Folliculitis
  • Furuncles
  • Carbuncles.
  • Abscesses
  • Impetigo (Newborn)
  • Scalded skin syndrome
• Streptococcal infections

  • Impetigo
  • Scarlet fever
  • Erysipelas
  • Necrotizing Fasciitis
• Acne (Pimple)

  • Propionibacterium acnes and other Propionibacterium spp..
  • Anaerobic,
  • Gram-positive bacilli
  • Not transmissible
• Sebum - an oily substance which helps keep the skin waterproof
• Sebum - carries dead skin cells out of pores
• Increased sebum and skin cell shedding can clog the pores
• Normal skin bugs can get trapped causing inflammation & infection; this results in painful pustules and nodules that we know as acne
• Untreated severe acne can cause permanent scarring
• Pimple types

  • Papules
  • Blackheads
  • Whiteheads
  • Nodules
  • Pustules
  • Cysts
• ANTHRAX (WOOLSORTER`S DISEASE)

  Types

  • SKIN – Cutaneous anthrax
  • LUNGS –Pulmonary anthrax
  • GIT- GIT anthrax
• Anthrax (Woolsorter's Disease)

  • Cause by Bacillus anthrasis
  • Gram positive bacilli
  • Encapsulated
  • Spore-forming
  • Transmission: Airborne and direct contact
  • Fatal for Pulmonary & GIT Anthrax
• GAS GANGRENE

  • Caused by Clostridium perfringens
  • Gram-positive bacilli in pairs or chain (Sometimes variable staining reaction)
  • Spore-forming
  • Can develop capsule
  • Non-motile
  • Obligate anaerobe
  • Vegetative pathogens produce necrotizing exoenzymes and toxins, which destroy muscle and soft tissue, allowing deeper penetration by the organisms.
  • Tissue destruction immediate amputations
  • Severe complications: shock and renal failure
  • Reservoir: Soil
  • Transmission: Contact with soil - contaminated spores ( to wound)