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Furunculosis

BASICS

  • Acute bacterial abscess of hair follicle; often caused by Staphylococcus aureus.
  • Synonyms: boils.
  • Systems: skin/exocrine.

EPIDEMIOLOGY

  • Predominant age: adolescents and young adults.
  • Clusters reported in teenagers in crowded settings or athletes.
  • Sex: male = female.
  • Exact prevalence unknown.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Infection spreads from follicle to surrounding dermis.
  • Usually S. aureus, increasingly CA-MRSA in the US; MSSA more common elsewhere.
  • Genetics unknown.

RISK FACTORS

  • Colonization by pathogenic Staphylococcus strains (nares, skin, axilla, perineum).
  • Rare PMN defects or hyper-IgE syndrome.
  • Diabetes mellitus, malnutrition, alcoholism, obesity, atopic dermatitis.
  • Primary and secondary immunodeficiencies (e.g., CVID, CGD, AIDS).
  • Medications impairing neutrophil function (e.g., omeprazole).
  • Positive family history predicts recurrence.

GENERAL PREVENTION

  • Patient education on hygiene and self-care.

COMMONLY ASSOCIATED CONDITIONS

  • Diabetes mellitus.
  • PMN defects (rare).
  • Hyper-IgE syndrome (rare).

DIAGNOSIS

History

  • Lesions on hair-bearing, friction-prone areas (beltline, thighs, nape, buttocks).
  • No systemic symptoms initially.
  • Lesions enlarge, become painful, may spontaneously drain pus.

Physical Exam

  • Painful erythematous papules/nodules (1–5 cm) with central pustule.
  • May be solitary or clustered.

Differential Diagnosis

  • Folliculitis
  • Pseudofolliculitis
  • Carbuncles
  • Ruptured epidermal cyst
  • Myiasis
  • Hidradenitis suppurativa
  • Atypical bacterial or fungal infections

DIAGNOSTIC TESTS & INTERPRETATION

  • Culture if multiple abscesses, cellulitis, systemic symptoms, or immunocompromised.
  • Consider immunoglobulin levels in recurrent/atypical cases.
  • Culture-directed antibiotic therapy.
  • Histopathology (rare): perifollicular necrosis, neutrophilic abscesses, S. aureus presence.

TREATMENT

General Measures

  • Warm moist compresses 30 min QID for comfort and drainage promotion.
  • Incision and drainage if abscess is large or pointing; packing as needed.
  • Routine culture unnecessary for localized abscess in nondiabetics with normal immunity.
  • Hygiene: daily changing of linens, clean shaving instruments, avoid nose picking, frequent dressing changes, no sharing personal items.

Medication

  • Systemic antibiotics usually unnecessary unless cellulitis, fever, abscess >2 cm, or immunocompromise.
  • First-line: Dicloxacillin 500 mg PO QID, cephalexin 500 mg PO QID, or clindamycin 300 mg TID (if penicillin-allergic).
  • For suspected MRSA: clindamycin 300 mg q6h, doxycycline 100 mg q12h, TMP-SMX DS 1 tab q8-12h, or minocycline 100 mg q12h.
  • Vitamin C 1000 mg/day for 4-6 weeks if impaired neutrophil function.
  • If antibiotics fail: trial of pentoxifylline 400 mg TID for 2–6 months (inhibits neutrophil activation).

ONGOING CARE

Follow-Up

  • See physician if compresses fail.
  • Monitor for recurrence; may require decolonization.

Diet

  • No restrictions.

PROGNOSIS

  • Usually self-limited; heals with or without scarring.
  • Recurrences often linked to chronic staphylococcal carriage; consider family member screening and mupirocin nasal ointment.
  • Efficacy of decolonization strategies unclear.

COMPLICATIONS

  • Scarring.
  • Bacteremia.
  • Seeding of infection to valves, joints, or other sites.

REFERENCES

  1. Lin H-S, Lin P-T, Tsai Y-S, et al. Interventions for bacterial folliculitis and boils (furuncles and carbuncles). Cochrane Database Syst Rev. 2021;2(2):CD013099.
  2. Fritz SA, Camins BC, Eisenstein KA, et al. Effectiveness of measures to eradicate Staphylococcus aureus carriage in patients with community-associated skin and soft-tissue infections: a randomized trial. Infect Control Hosp Epidemiol. 2011;32(9):872-880.
    Additional Reading:
  3. Balakirski G, Hischebeth G, Altengarten J, et al. Recurrent mucocutaneous infections caused by PVL-positive Staphylococcus aureus strains: a challenge in clinical practice. J Dtsch Dermatol Ges. 2020;18(4):315-322.
  4. Ibler KS, Kromann CB. Recurrent furunculosis—challenges and management: a review. Clin Cosmet Investig Dermatol. 2014;7:59-64.
  5. Nowicka D, Grywalska E. Staphylococcus aureus and host immunity in recurrent furunculosis. Dermatology. 2019;235(4):295-305.

CODES

  • ICD10: L02.92 Furuncle, unspecified
  • ICD10: L02.12 Furuncle of neck
  • ICD10: L02.429 Furuncle of limb, unspecified

CLINICAL PEARLS

  • Pathogens vary by locality; stay updated on local epidemiology.
  • Small number of furuncles do not require antibiotics unless systemic symptoms or cellulitis.
  • MRSA treatment options include clindamycin, doxycycline, TMP-SMX, minocycline, linezolid, vancomycin (IV).
  • Folliculitis, furunculosis, and carbuncles represent a spectrum of pyodermas.
  • Decolonization should be culture-confirmed due to resistance risk and uncertain benefit.