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Furuncles
are skin abscesses caused by staphylococcal infection, which involve
a hair follicle and surrounding tissue. Carbuncles are clusters of
furuncles connected subcutaneously, causing deeper suppuration and
scarring. They are smaller and more superficial than subcutaneous abscesses
(see Bacterial Skin Infections: Cutaneous Abscess). Diagnosis
is by appearance. Treatment is warm compresses and often oral antistaphylococcal
antibiotics.
Both furuncles and carbuncles may affect healthy young people but are more common in the obese, the immunocompromised (including those with neutrophil defects), the elderly, and possibly those with diabetes. Clustered cases may occur among those living in crowded quarters with relatively poor hygiene or among contacts of patients infected with virulent strains. Predisposing factors include bacterial colonization of skin or nares, hot and humid climates, and occlusion or abnormal follicular anatomy (eg, comedones in acne).
Furuncles are common on the neck, breasts, face, and buttocks. They are uncomfortable and may be painful when closely attached to underlying structures (eg, on the nose, ear, or fingers). Appearance is a nodule or pustule that discharges necrotic tissue and sanguineous pus. Carbuncles may be accompanied by fever and prostration.
Diagnosis is by examination. Material for culture should be obtained from patients with single furuncles on the nose or central face, from patients with multiple furuncles, and from immunosuppressed patients.
Treatment of a single lesion is intermittent hot compresses to allow it to point and drain spontaneously. A patient with a furuncle in the nose or central facial area or with multiple furuncles or carbuncles is given a penicillinase-resistant beta-lactam (eg, dicloxacillin or cephalexin 250 to 500 mg po qid). Use of initial empiric therapy against MRSA is not typically advised unless there is compelling clinical evidence (eg, contact with a documented case or outbreak; high culture-documented prevalence in a practice area). If resistant strains or complicated infection is clinically suspected, alternate empiric choices include trimethoprim-sulfamethoxazole , levofloxacin , and moxifloxacin . Systemic antibiotics are also needed for larger lesions, lesions that do not respond to topical care, evidence of expanding cellulitis, immunocompromised patients, and patients at risk of endocarditis.
Incision and drainage are occasionally necessary and are indicated to speed resolution when the furuncle or carbuncle is fluctuant.
Furuncles frequently recur and can be prevented by applying of liquid soap containing either chlorhexidine gluconate with isopropyl alcohol or 2 to 3% chloroxylenol by giving maintenance antibiotics over 1 to 2 mo. Patients with recurrent furunculosis should be treated for predisposing factors such as obesity, diabetes, occupational or industrial exposure to inciting factors, and nasal carriage of Staphylococcus
aureus or methicillin-resistant S.
aureus (MRSA) colonization.
Last full review/revision October 2007 by A. Damian Dhar, MD
Content last modified October 2007
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