Purulent cellulitis is characterized by purulent discharge or skin abscesses, including ingrown toenail infections.
Studies have shown that purulent material is usually (~80%) positive for S. aureus.
In these cases, drainage is important as it is both diagnostic (cultures) and therapeutic. S. aureus can be methicillin susceptible (MSSA) or methicillin resistant (MRSA). If patient is not very ill and has no risk factors for MRSA, one can treat with cloxacillin or cephalexin and wait for culture results. If the patient has risk factors for MRSA, one can treat empirically with TMP-SMX or doxycycline (which can be safely used for short term therapy even in children <8 years old) as outpatient, or vancomycin if admitted, bearing in mind that these drugs are inferior treatments for MSSA.
