Abscess

An abscess is defined as an "accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection."

Incision and drainage
The abscess should be treated with incision and drainage.

Packing
Although packing of the abscess cavity is commonly done after drainage, it may delay healing. To address this question, a randomized controlled trial was started in Sept. 2008 and is ongoing as of Dec. 2008.

Primary closure
Primary closure has been successful when combined with curettage and antibiotics or with curettage alone. However, another randomized controlled trial found primary closure led to 35% failing to heal primarily and primary closure longer median number of days to closure (8.9 versus 7.8).

In anorectal abscesses, primary closure healed faster, but 25% of abscesses healed by secondary healing and recurrence was higher.

Antibiotics
Antibiotics should be considered if there is significant overlying cellulitis. Systematic reviews of relevant studies concluded that:
 * "the current literature does not support the routine practice of prescribing antibiotics after incision and drainage of simple cutaneous abscesses, even in high-MRSA-prevalence areas"
 * "our conclusions cannot be extrapolated to those cases in which there is a significant degree of overlying cellulitis"

A clinical practice guideline by the Infectious Disease Society of American concludes that "gram stain, culture, and systemic antibiotics are rarely necessary" ; however, according the National Guideline Clearinghouse summary of this guideline, the guideline was not a systematic review of the evidence.

A more recent randomized controlled trial confirms these results ; although in this trial 87.8% were methicillin-resistant staphylococcus aureus (MRSA) yet the antibiotic used was cephalexin. It is not known if an antibiotic effective against MRSA would have reducted the rate of treatment failures below the 10% failure rate observed in the trial. Older trials also are available.

In observational cohort studies of patients with MRSA, one study found there was "no significant differences" (rates not provided by the article) among patients treated with appropriate antibiotics versus those treated without appropriate antibiotics. A second cohort study found that all five (100%) of children treated with appropriate antibiotics improved as compared to 58 of 62 (94%) treated with ineffective antiobiotics.

Prevention
To prevent recurrent infections due to Staphylococcus aureus, consider the following measures:
 * Topical mupirocin applied to the nares. In this randomized controlled trial, patients used nasal mupirocin twice daily 5 days a month for 1 year.
 * Chlorhexidine baths, in a randomized controlled trial, nasal recolonization with S. aureus occurred at 12 weeks in 24% of nursing home residents receiving mupirocin ointment alone (6/25) and in 15% of residents receiving mupirocin ointment plus chlorhexidine baths daily for the first three days of mupirocin treatment (4/27). Although these results did not reach statistical significance, the baths are easy to do.