[Soft-tissue infections].

One of the soft-tissue infections with a large clinical relevance is necrotizing fascitis produced by Streptococcus pyogenes and skin infections produced by Staphylococcus aureus, particularly due to the evermore frequent methylcillin (MRSA) resistant varieties. In necrotizing fascitis the diagnostic delay as well as the delay in the indication for surgical debridement influence both the prognosis and a high mortality related to these infections. Two clinical forms have been described: Type I caused by at least one anaerobic species in combination with facultative anaerobes, more frequent in diabetics or patients with peripheral vascular disease; type II, monomicrobial, produced by group A beta hemolytic Streptococcus and with a lesser frequency by Staphylococcus aureus. Among the recognized risk factors diabetes mellitus, peripheral vascular disease, chronic renal failure, alcoholism, cancer, malnutrition, steroid and/or immunosuppressant treatment and the use of intravenous parenteral drugs are widely recognized. Therapeutics is based on hemodynamic support, antibiotic therapy and an early surgical approach with the elimination of all of the necrotic and devitalized tissue. Infections frequently associated to community-acquired MRSA are those present in skin and soft-tissue. Some population groups have been described as at-risk, but there is also an increase in the number of patients with no risk factors. Also, national and international registries of anti-TNF therapies have demonstrated the increase of soft-tissue infections in patients with rheumatoid arthritis treated with these agents. Other biologic drugs such as rituximab, abatacept or anakinra do not seem to be associated to an increase in these infections.