Complicated infections of skin and skin structures: when the infection is more than skin deep.

Skin and skin-structure infections are common, and range from minor pyodermas to severe necrotizing infections. Complicated infections are defined as involving abnormal skin or wounds, occurring in compromised hosts, or requiring surgical intervention. Classification schemes for these infections are varied and confusing. Distinguishing characteristics include the aetiological agent(s), clinical context and findings, depth of tissue involvement and rate of progression. The most common pathogens are aerobic Gram-positive cocci, but complicated infections frequently involve Gram-negative bacilli and anaerobic bacteria. Initial antibiotic therapy is usually empirical, and later modified by the results of stains and cultures of wound specimens. Broad-spectrum coverage is frequently needed for complicated infections. Ertapenem is a once-a-day parenteral Group 1 carbapenem antibiotic, recently licensed in the USA and Europe, which may assume an important role in treating some complicated skin and skin-structure infections. Surgical debridement is important for many complicated infections, and is the critical element in managing necrotizing fasciitis and myonecrosis.