With involvement of several adjacent follicles, a mass called a carbuncle may occur, with pus discharging from multiple follicular orifices. This infection typically develops on the back of the neck and appears more commonly in patients with diabetes than in the general population. Moist heat is usually adequate for small furuncles, which ordinarily drain spontaneously. Incision and drainage are appropriate for large or multiple furuncles and for all carbuncles. Systemic antibiotics are unnecessary unless there is fever or substantial surrounding cellulitis.
Some patients have recurrent episodes of furunculosis.
From this site or occasionally from the perineum or axilla, organisms can spread and enter the skin, presumably through minor, usually inapparent, trauma. Successful prevention of recurrent infection requires eradication of these bacteria from their site of residence, but most systemic antibiotics do not achieve adequate levels of drug in the anterior nares. An exception is clindamycin, which, when given as a single daily dose of 150 mg for 3 months, is very effective in preventing subsequent episodes. A less effective alternative is mupirocin ointment, applied in the anterior nares twice daily for 5 days each month. Occasionally, however, the resident skin flora causes cutaneous infections, especially with trauma or alterations in the stratum corneum.