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The skin consists of the superficial epidermis, dermis, and deeper
subcutaneous tissues (Figure 147-1). The
lymphatics run parallel with the blood vessels. Cellulitis is
an infection of the deep dermis and subcutaneous fat of the skin. Erysipelas is
a more superficial skin infection involving the upper dermis with
prominent lymphatic involvement. Folliculitis is an
infection of the hair follicle. Skin abscesses are
collections of pus within the dermis and deeper skin tissues, potentially
into the subcutaneous tissues. Furuncles are single,
deep nodules involving the hair follicle that are often suppurative. Carbuncles are
formed by multiple interconnecting furuncles that drain through
several openings in the skin. Methicillin-resistant Staphylococcus
aureus (MRSA) can cause any of the above
disorders, and is discussed first because it is a common cause of
soft tissue infections.
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MRSA infections can develop in hospitalized patients, in patients
with health care–related risk factors, and in otherwise
healthy patients without known risk factors (Table
147-1).1,2
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Community-acquired MRSA (CA-MRSA) is epidemic across all populations,
regardless of risk factors or geographic location.3–5 As
much as 59% of purulent skin and soft tissue infections
in patients >18 years old3 and up to 75% of
purulent skin abscesses in children are caused by MRSA.4,5
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CA-MRSA strains possess unique clinical and microbiologic
characteristics that distinguish them from the ...