Furunculosis – Causes, Symptoms, Diagnosis, Treatment and Ongoing care
Acute bacterial abscess of a hair follicle (often Staphylococcus aureus):
- System(s) affected: Skin/Exocrine
- Synonym(s): Boils
- Predominant age:
- Adolescents and young adults
- Clusters have been reported in teenagers living in crowded quarters, within families, or in high school athletes.
- Predominant sex: Male = Female
Exact data are not available.
- Carriage of pathogenic strain of Staphylococcus sp. in nares, skin, axilla, and perineum
- Rarely, polymorphonuclear leukocyte defect or hyperimmunoglobulin E–Staphylococcus sp. abscess syndrome
- Diabetes mellitus, malnutrition, alcoholism, obesity, atopic dermatitis
- Primary immunodeficiency disease and AIDS (common variable immunodeficiency, chronic granulomatous disease, Chediak-Higashi syndrome, C3 deficiency, C3 hypercatabolism, transient hypogammaglobulinemia of infancy, immunodeficiency with thymoma, Wiskott-Aldrich syndrome)
- Secondary immunodeficiency (e.g., leukemia, leukopenia, neutropenia, therapeutic immunosuppression)
- Medication impairing neutrophil function (e.g., omeprazole)
Patient education regarding self-care (see General Measures); treatment and prevention are interrelated.
Infection spreads away from hair follicle into surrounding dermis.
Pathogenic strain of S. aureus (usually); increasing incidence of community-acquired methicillin-resistant S. aureus (CA-MRSA)
Commonly Associated Conditions
- Usually normal immune system
- Diabetes mellitus
- Polymorphonuclear leukocyte defect (rare)
- Hyperimmunoglobulin E–Staphylococcus sp. abscess syndrome (rare)
- See Risk Factors.
- Located on hair-bearing sites, especially areas prone to friction or repeated minor traumas (e.g., underneath belt, anterior aspects of thighs, nape, buttocks)
- No initial fever or systemic symptoms
- The folliculocentric nodule may enlarge, become painful, and develop into an abscess (frequently with spontaneous drainage).
- Painful erythematous papules/nodules (1–5 cm) with central pustules
- Tender, red, perifollicular swelling, terminating in discharge of pus and necrotic plug
- The lesions may be solitary or clustered.
Diagnostic Tests & Interpretation
Initial lab tests
Culture of the purulent contents
Follow-Up & Special Considerations
- Immunoglobulin levels in rare (e.g., recurrent or otherwise inexplicable) cases
- If culture grows gram-negative bacteria or fungus, consider polymorphonuclear neutrophil leukocyte functional defect
Histopathology (though a biopsy is rarely needed):
- Perifollicular necrosis containing fibrinoid material and neutrophils
- At deep end of necrotic plug, in subcutaneous tissue, is a large abscess with a Gram stain positive for small collections of S. aureus.
- Ruptured epidermal cyst
- Myiasis (larva of botfly/tumbafly)
- Hidradenitis suppurativa
- Atypical bacterial or fungal infections
- If suspect CA-MRSA, see Second Line.
- If abscesses multiple, if lesions have marked surrounding inflammation, cellulitis, systemic symptoms such as fever, or if immunocompromised:
- Obtain culture, and place on antibiotics directed at S. aureus × 10–14 days.
- Dicloxacillin (Dynapen, Pathocil) 500 mg p.o. q.i.d. or
- Cephalexin 250 mg p.o. q.i.d. or
- Clindamycin 150 mg q.i.d. if penicillin-allergic
- Suppression of pathogenic strain (if topical treatment fails):
- Dicloxacillin/cloxacillin 500 mg b.i.d. × 10–14 days
- Cephalexin or clindamycin (if penicillin-allergic)
- If preceding fails, dicloxacillin/cloxacillin 500 mg plus rifampin 600 mg p.o. daily × 7–10 days or clindamycin 150 mg/d × 3 months (1)[C]
- Contraindications: Allergy to the particular drug selected
- Precautions: Cloxacillin and dicloxacillin: Anaphylactic reaction
- Resistant strains of S. aureus (MRSA): Clindamycin 300 mg q6h or doxycycline 100 mg q12h or TMP-SMX DS 1 tab q8h or minocycline 100 mg q12h (2)[C]
- If known or suspected impaired neutrophil function (e.g., impaired chemotaxis, phagocytosis, superoxide generation), add vitamin C 1,000 mg/d × 4–6 weeks (prevents oxidation of neutrophils)
- If fail with antibiotic regimens:
- May try oral pentoxifylline 400 mg t.i.d. × 2–6 months (3)[C]
- Contraindications: Recent cerebral and/or retinal hemorrhage; intolerance to methylxanthines (e.g., caffeine, theophylline); allergy to the particular drug selected
- Precautions: Prolonged prothrombin time (PT) and/or bleeding; if on warfarin, frequent monitoring of PT
- Moist, warm compresses (provide comfort, encourage localization/pointing/drainage) 30 minutes q.i.d.
- If pointing or large, incise and drain
- Consider packing.
- Routine culture not necessary for localized abscess in nondiabetic patients with normal immune system
- Systemic antibiotics usually unnecessary, unless extensive surrounding cellulitis or fever
- If recurrent, usually related to chronic skin carriage of Staphylococci (nares or on skin). Treatment goals are to decrease or eliminate pathogenic strainor suppress pathogenic strain:
- Culture nares, skin, axilla, and perineum (culture nares of family members).
- Apply mupirocin ointment to anterior nares b.i.d. × 5 days (patient and family members/carriers).
- Culture anterior nares every 3 months. If failure, retreat with mupirocin or consider oral antibiotics (4)[C].
- See Medications, First Line, Suppression of Pathogenic Strain.
- Especially in recurrent cases, wash entire body and fingernails (with nailbrush) daily for 1–3 weeks with povidone–iodine (Betadine), hexachlorophene (Hibiclens), or pHisoHex soap (all can cause dry skin)
- Sanitary practices: Change towels, washcloths, and sheets daily; clean shaving instruments; avoid nose picking; change wound dressings frequently; do not share items of personal hygiene.
Instruct patient to see physician if compresses unsuccessful
- Self-limited: Usually drains pus spontaneously and will heal with or without scarring within several days
- Recurrent/chronic: May last for months or years
- Seeding (e.g., septal/valve defect, arthritic joint)
1. Klempner MS, Styrt B. Prevention of recurrent staphylococcal skin infections with low-dose oral clindamycin therapy. JAMA. 1988;260:2682–5.
2. Up To Date 2007. Impetigo, Folliculitis, Furunculosis, and Carbuncles.
3. Wahba-Yahav AV. Intractable chronic furunculosis: prevention of recurrences with pentoxifylline. Acta Derm Venereol. 1992;72:461–2.
4. Doebbeling BN, et al. Long Term Efficacy of Intranasal Mupirocin, A Prospective Cohort Study of Staphylococcal Aureus. Arch Int Med.1994;154:1505.
5. Winthropp KL, et al. An outbreak of mycobacterium furunculosis associated with footbaths at a nail salon. N Engl J Med. 2002;346(18):1366–71.
Frazee BW, Lynn J, Charlebois ED, Lambert L, Lowery D, Perdreau-Remington F et al. High prevalence of methicillin-resistant Staphylococcus aureus in emergency department skin and soft tissue infections. Ann Emerg Med.2005;45:311–20.
See Also (Topic, Algorithm, Electronic Media Element)
Folliculitis; Hidradenitis Suppurativa
680.9 Carbuncle and furuncle of unspecified site
40603000 furunculosis of skin and/or subcutaneous tissue (disorder)
- The pathogens may be different in different localities. Keep up-to-date with the locality-specific epidemiology.
- If few, furuncles/furunculosis do not always need antibiotic treatment. If systemic symptoms (e.g., fever), cellulitis, or multiple lesions occur, oral antibiotic therapy is needed.
- Other treatments for MRSA include linezolid p.o. or IV and IV vancomycin.
- Folliculitis, furunculosis, and carbuncles are parts of a spectrum of pyodermas.
- Other causative organisms include anaerobic (e.g., Escherichia coli, Pseudomonas aeruginosa, and Streptococcus faecalis), anaerobic (e.g.,Bacteroides, Lactobacillus, Peptobacillius), and Peptostreptococcus), andMycobacteria (5).