Skin infections

• Macules


  Flat lesions characterized by change in color (red) of the affected region
• Papules


  Raised solid lesions, <5mm in diameter
• Vesicle


  Circumscribed, fluid-filled lesions < 5mm in diameter
• Pustule


  Circumscribed, exudate-filled lesions
• Plaque


  Plateau-like solid elevation that occupies a relatively large area (>5mm in diameter)
• Psoriasis vulgaris


  • Presents as the well-demarcated pink plaques surrounded by silvery scales
• Nodule


  Rounded raised lesions >5mm in diameter
• Bullae


  Circumscribed fluid-filled lesions > 5mm in diameter
• Abscess


  A pink erythematous, warm, tender fluctuant nodule that may be associated with other signs of infection such as fever
• Furuncle


  A deep necrotizing folliculitis with suppuration, presents as inflamed follicle-centered nodule usually > 1cm with a central necrotic plug and an overlying pustule
• Carbuncle


  An abscess in the skin caused by the bacterium Staphylococcus aureus, usually involves a group of hair follicles and is therefore larger than a typical furuncle, can have one or more openings onto the skin and may be associated with fever or chills
• Purpura


  Extravasation of red blood from cutaneous vessels into the skin or mucosal membrane
• Petechiae


  Small, purpuric lesions < 3mm across
• Ecchymoses


  Larger extravasations of blood (> 3mm)
• Eschar


  Circumscribed, adherent, hard, black crust on the surface of the skin, implies tissue necrosis, infarction, deep burns, gangrene or other ulcerating process
• Ulcer


  A defect in which the epidermis and at least the upper dermis (papillary dermis) has been removed, hindering re-epithelialization and healing with scarring
• Impetigo


  Starts as a red sore that ruptures, oozes for a few days and then forms a honey-colored crust, sores mainly occur around the nose, mouth and limbs in infants and children
• Cellulitis


  Usually a superficial infection of the skin, can spread into lymph nodes and bloodstream if severe or left untreated
• Staphylococcal scalded skin syndrome (SSSS)

  An illness characterized by red blistering skin that looks like a burn or scald, caused by the release of two exotoxins (epidermolytic toxins A and B) from toxigenic strains of the bacteria Staphylococcus aureus
• Characteristics of the SSSS rash

  • Tissue paper-like wrinkling of the skin followed by large fluid-filled blisters, rash spreads to other parts of the body, top layer of skin begins peeling off in sheets, Nikolsky sign is positive
• Staphylococcal skin infections


  • Folliculitis
  • Sty or hordeolum
  • Furuncle (boil)
  • Carbuncle
• Erysipelas


  Affects the upper layers of the skin, characterized by a painful and shiny light-red swelling of a quite clearly defined area of skin
• Cellulitis


  The reddened skin is less clearly defined than in erysipelas, often dark-red or slightly purplish, the infection reaches the lower layers of skin and the tissue beneath it
• Necrotizing Fasciitis


  Also referred to as "flesh-eating" or streptococcal gangrene, affects deep subcutaneous tissue, begins as cellulitis progressing into bullous and gangrenous stages, spreading to fascia, muscle, and fat, can lead to systemic complications, multi-organ failure, and death if untreated
• Acne vulgaris


  A chronic skin condition that results when dead skin cells and oil from the skin clog hair follicles, primarily affects skin rich in oil glands, including the face, upper part of the chest, and back
• Cutibacterium acnes


  Anaerobic Gram + bacilli that contributes to the development of acne, but its exact role is not well understood
• Anthrax, Woolsorter Disease


  Caused by Bacillus anthracis, a spore-forming, Gram + bacillus
• Gas gangrene (myonecrosis)


  A life threatening infection following physical trauma or surgery characterized by massive tissue necrosis with gas formation, shock, renal failure and death within 48 h of onset, caused by anaerobic bacteria in the genus Clostridium, especially Clostridium perfringens
• Wound infections


  Result when protective skin barrier is broken, opportunistic indigenous microbiota and environmental bacteria can invade and cause local or deep tissue infections, pathogens may spread through blood or lymph, causing serious systemic infections
• Hansen's disease (leprosy)


  An infection caused by slow-growing bacteria called Mycobacterium leprae, affects the nerves, skin, eyes, and lining of the nose (nasal mucosa), curable with early diagnosis and treatment
• Clinical presentation and prognosis of Hansen's disease


  • If left untreated, can result in paralysis of hands and feet, multiple injuries due to lack of sensation, reabsorption of affected digits, corneal ulcers and blindness, loss of eyebrows and saddle-nose deformity
• Transmission of Hansen's disease


  Droplet transmission, prolonged, close contact with someone with untreated leprosy over many months is needed to catch the disease, overall risk is very low (>95% have natural immunity)
• Countries with high incidence of Hansen's disease

  • Africa: Democratic Republic of Congo, Ethiopia, Madagascar, Mozambique, Nigeria, United Republic of Tanzania
  • Asia: Bangladesh, India, Indonesia, Myanmar, Nepal, Philippines, Sri Lanka
  • Americas: Brazil
• Treatment of Hansen's disease


  Treated with a combination of antibiotics, typically 2 or 3 used at the same time, treatment usually lasts between one to two years, can be cured if treatment is completed as prescribed
• Tinea versicolor


  Caused by Malassezia furfur (Pityrosporum orbiculare), a normal skin flora, characterized by irregular pigmented macules with dry, scaly appearance typically found on the face, neck, trunk, and arms
• Tinea nigra


  Caused by Hortaea werneckii (formerly Exophiala werneckii), a dematiaceous fungus, characterized as gray to black, well-demarcated macules, typically affecting the palms and soles
• Dermatophytosis (Tinea ["Ringworm"] Infections, Dermatomycosis)

  Caused by various species of filamentous fungi, including Microsporum, Epidermophyton, and Trichophyton spp., collectively referred to as dermatophytes
• Chromoblastomycosis of the Foot


  One of the most frequent infections caused by melanized fungi, a subcutaneous fungal infection, usually an occupational related disease, mainly affecting individuals in tropical and temperate regions
• Warts


  Caused by Human Papillomavirus (HPV), a DNA virus belonging to the Papovaviridae family, acquired through direct contact via mucosal or skin breaks, sexual contact, or passage through an infected birth canal
• Types of warts


  • Skin Warts
  • Genital and Anogenital Warts