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A systematic search of the medical literature was performed in
January, 2008. The search, limited to human subjects and English
language journals, included MEDLINE®, PubMed,
the Cochrane Database of Systematic Reviews, and UpToDate®.
The current Infectious Disease Society of America practice guidelines
for management of skin and soft tissue infections and those for
diabetic foot infections can be found at www.idsociety.org.
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The skin serves as a barrier between humans and their environment
and therefore functions as a primary defense mechanism against infections.
The skin consists of the following layers and structures: (1) the
epidermis, the outermost nonvascular layer of the skin, (2) the
dermis, the layer of skin directly beneath the epidermis which consists
of connective tissue containing blood vessels and lymphatics, sensory
nerve endings, sweat and sebaceous glands, hair follicles, and smooth-muscle
fibers, and (3) the subcutaneous fat, a layer of loose connective
tissue beneath the dermis which primarily consists of fat cells.
Beneath the subcutaneous fat lies the fascia, which separates the
skin from underlying muscle. Skin and soft tissue infections (SSTIs)
may involve any or all layers of the skin, fascia, and muscle. They
may also spread far from the initial site of infection and lead
to more severe complications, such as endocarditis, sepsis, or streptococcal glomerulonephritis.
The treatment of SSTIs may at times necessitate both medical and
surgical management. Various infections of the skin are a common
reason for patients seeking attention from primary care providers;
cellulitis was listed as the primary reason for office visits in
approximately 2% of members of one health plan.1 It
is therefore imperative that primary care providers have adequate
knowledge of the appropriate evaluation and management of common
SSTIs.
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Bacterial infections of the skin can broadly be classified as
primary or secondary (see Table 42-1).2 Primary bacterial
infections usually involve areas of previously healthy skin and
are typically caused by a single pathogen. In contrast, secondary
infections occur in areas of previously damaged skin and are frequently
polymicrobic. SSTIs are also classified as complicated or uncomplicated.
Infections are considered complicated when they involve deeper skin
structures (fascia, muscle layers, etc.), require significant surgical
intervention, or occur in patients with compromised immune function
(diabetes mellitus, human immunodeficiency virus [HIV],
etc.).3
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The skin and subcutaneous tissues are normally extremely resistant
to infection but may become susceptible under certain conditions.
Even when high concentrations of bacteria are applied topically
or injected into the soft tissue, resultant infections are rare.
The majority of SSTIs result ...