Clinical Information

Skin and soft tissue infections can occur as a result of a break in the skin surface, or they can occur as complications of surgery, trauma, human animal, or insect bites or diseases that interrupt a mucosal or skin surface.  The primary agents of skin and tissue infections are Staphylococcus aureus, Pseudomonas aeruginosa, members of the Enterobacteriaceae, beta-hemolytic streptococci, and anaerobes.  A much broader microbial diversity can also be recovered from deep wound, invasively collected abscess/fluid and tissue specimens. Tissues collected during surgery or fine-needle biopsy are the best types of specimen to obtain for microbiology culture.  Antimicrobial susceptibility testing should be performed on pure culture isolates of pathogenic (or potentially pathogenic in special situations) bacteria grown from specimens that have been appropriately collected so as not to confuse clinically significant isolates with normal flora. Antimicrobial susceptibility testing determines the minimal inhibitory concentration (MIC) value of selected antimicrobial agents against isolated potentially pathogenic bacteria. The MIC is the lowest antimicrobial concentrations (of a series of increasing concentrations) that inhibits growth of the bacterium. For each organism-antimicrobial agent combination, the Clinical and Laboratory Standards Institute and/or the FDA on Antimicrobial Susceptibility Testing provides interpretive criteria for determining whether the MIC should be interpreted as susceptible, intermediate, nonsusceptible or resistant.