When considering common
bacterial diseases of the skin, rather distinct clinical responses to a variety of
bacterial infections have been identified. In these cases, it is the specific site of
infection and the attendant inflammatory responses that provide the characteristic clinical picture. When the
pyoderma extends just below the stratum corneum, it is called
impetigo. Nonbullous
impetigo is the most common pediatric skin
infection. It usually starts in a traumatized area. The typical lesion begins as an erythematous papule, after which it becomes a unilocular vesicle. When the subcorneal vesicle becomes pustular, it
ruptures and eventually becomes a yellow, golden crust that is a hallmark of the disease process. Bullous
impetigo is a less common form of
impetigo, accounting for fewer than 30% of all
impetigo cases. It occurs in infants and is characterized by rapid progression of vesicles to the formation of
bullae measuring larger than 5 mm in diameter in previously untraumatized skin. Treatment of nonbullous
impetigo must include intervention against the pathogen as well as improvements in the hygiene and living conditions of the patient. A fundamental tenet is to debride the crust (scab) from the
wound surface using
poloxamer 188. If the lesions are not widespread, topical
mupirocin is the treatment of choice. Treatment of bullous
impetigo is similar, except that the local cleansing and topical
antibiotic must be complemented by systemic
antibiotics if there is evidence of disseminating
infections.
Ecthyma is usually a consequence of failure to treat effectively
impetigo. The untreated
infection extends deep into the tissue in shallow ulcerations that often heal without
scar. Treatment for
ecthyma usually requires systemic
antibiotics against either staphylococcus or streptococcus.
Folliculitis is a
pyoderma located within a hair follicle, secondary to follicular occlusion by
keratin,
overhydration, or either bacterial or
fungal infection.
Folliculitis may be divided into either a deep or a superficial type. In the superficial type, the pustule is located at the opening of the hair follicle. In the deep form, the
infection may extend beyond the confines of the hair follicle, becoming a furuncle or boil.
Carbuncles are aggregates of interconnected
furuncles that drain through multiple openings of the skin. Treatment of
folliculitis must include searching for and avoiding any factors predisposing to
infection. If topical
antibiotic therapy is ineffective in controlling the
infection, surgical drainage of the infected skin
abscess will be necessary.
Paronychia is the most common
bacterial infection of the hand, which often requires surgical incisional drainage. Similarly, a felon that is an
infection of the distal pulp of a finger usually requires surgical drainage. Finally,
cellulitis is an acute inflammatory reaction involving the skin and underlying subcutaneous tissue. It usually starts as
erysipelas and may advance to
lymphangitis,
lymphadenitis, or
gangrene,which will respond to life-saving interventions in the hospital that usually include systemic
antibiotic treatment as well as surgical intervention.