[Primary cutaneous infections due to Staphylococcus and Streptococcus].

Pyodermitis constitutes a very important chapter in dermatological practice. Its pathogenesis, in special the one caused by S. aureus, has improved due to the knowledge of the role developed by the host defensins, quorum-sensing signaling and the Panton-Valentine leucocidin gene among others. As well, exfoliative toxins and enterotoxins responsible for the staphylococal scalded skin syndrome (SSSS) and toxic shock syndrome, respectively, have been cloned. Also, it has been seen that bullous impetigo, SSSS and pemphigus foliaceus share a common target: desmoglein-1. The Panton-Valentine leucocidin gene has been related to the appearance of abscesses, necrotic cutaneous lesions and furuncles in young persons caused by meticillin resistant S. aureus, with its epidemiological implications. Finally, some atypical forms of erysipelas suppose a diagnostic challenge for the dermatologist.