Infections caused by P aeruginosa involving the skin may be primary or secondary. Secondary infections have been described above and include ecthyma gangrenosum, subcutaneous nodules, vesicles, bullae, cellulitis, deep abscesses, and necrotizing fasciitis. Primary skin lesions are noted as complications of neutropenia, burns, decubitus ulcers, prematurity, exposure to a moist environment, and hydrotherapy. Burn wound sepsis is a serious complication that may be caused by P aeruginosa.
Colonization of the burn may lead to invasive disease. The signs are black, brown, or violet discoloration of the burn eschar; destruction of granulation tissue leading to rapid eschar separation and subcutaneous hemorrhage; erythematous nodules; edema or hemorrhage of adjacent uninfected tissue; black neoeschar formation; or signs of septicemia. This complication of burns has a high associated mortality. Diagnosis is by skin biopsy of both burn tissue and adjacent viable tissue. The presence of > 105 organisms per gram of tissue cultured, the presence of P aeruginosa in adjacent healthy tissue, vasculitis, or inflammation at the burn margin are diagnostic.
Other skin and soft tissue infections caused by P aeruginosa include the following: hot tub- or hydrotherapy-associated folliculitis, which is usually self-limited; web space infection of the toe associated with humid climates or tinea pedis infection and characterized by maceration and scaling with purulent discharge, which may be green in color; green nail syndrome, which is characterized by paronychia occurring in association with a history of frequent submersion of the hands in water and nail discoloration caused by incorporation of pigment in the nail; green foot syndrome resulting from P aeruginosa colonization of rubber-soled shoes producing pigment that stains the feet, but in which P aeruginosa does not cause direct infection; diving suit dermatitis; necrotizing fasciitis after Cesarean section, and noma neonatorum, a complication of premature infants in developing countries where necrotizing hemorrhagic lesions of mucosal surfaces or the groin result in fulminant infection and often death.