Acute bacterial skin and skin structure infections (ABSSSIs) are a subgroup of skin and soft tissue infections (SSTIs), which are commonly occurring microbial infections of the epidermis, dermis and subcutaneous tissues For the purpose of clinical trial design, ABSSSIs are defined by FDA guidance to include such conditions as cellulitis/erysipelas, wound infections, burn infections, cutaneous abscesses, and impetigo. Infections of animal or human bites, necrotizing fasciitis, diabetic foot infections, decubitus ulcer infections, myonecrosis, ecthyma gangrenosum, and catheter-site infections are specifically excluded because they generally require different medical management than ABSSSI.
SSTIs can have diverse etiologies, and identification of the causative agent is often difficult; however, the majority of SSTIs are caused by Staphylococcus aureus and streptococci. The economic burden associated with SSTIs is substantial and growing. Total hospital admissions for SSTIs increased by 29 percent between 2000 and 2004 and the number of visits (and visit rate) to ambulatory care facilities increased from 8.6 million (32.1 visits per 1000 population) to 14.2 million visits (48.1 per 1000) between 1997 and 2005. These increases have been attributed largely to increasing resistance to antibacterial drug agents among the microorganisms that most commonly cause these infections especially methicillin-resistant Staphylococcus aureus (MRSA) According to a recent study, the total economic burden of S. aureus infection was estimated to be $14.5 billion for all inpatient stays in 2003