Skin and skin structure infections (SSSIs), also referred to as skin and soft tissue infections (SSTIs),[1] or acute bacterial skin and skin structure infections (ABSSSIs),[2] are infections of skin and associated soft tissues (such as loose connective tissue and mucous membranes).[citation needed] Historically, the pathogen involved has most frequently been a bacterial species—always, since redescription of SSSIs as ABSSSIs—and as such, these infections require treatment by antibiotics.[citation needed]