Bacterial skin and soft tissue infections are frequent and represent one of the most important differential diagnoses in patients presenting with reddened and swollen skin and soft tissue. Among these infections, cellulitis (phlegmon), erysipelas and abscesses are the most frequent. Whereas erysipelas is almost exclusively caused by streptococci and can be successfully treated with penicillin, an effective antibiotic therapy targeted at Staphylococcus aureus should be empirically considered for abscesses and phlegmon; other pathogens, such as gram negative and anaerobic bacteria can be found in patients with the corresponding underlying disease and certain risk factors. Severe necrotizing soft tissue infections are acutely life-threatening and require rapid and broad antibiotic therapy followed by immediate surgery. Depending on the medical history or exposure (including bite wounds), other pathogens may have to be considered in special situations including the increasing prevalence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) outside hospitals.