folliculitis

Introduction

Infection with inflammation of an upper segment of hair follicle.

Etiology

• bacterial
  • Staphylococcus aureus (most common)
    • MRSA
  • Propionibacterium acnes
  • Pseudomonas aeruginosa (hot tub folliculitis)
  • gram-negative bacilli
    • associated with systemic antibiotic therapy of acne vulgaris
    • often Escherichia coli
  • secondary syphilis
• fungal
  • Dermatophytes
  • Pityrosporum
  • Candida
• viral
  • Herpes simplex
  • HIV (eosinophilic folliculitis)
• Demodicidosis (Demodex)
• predisposing factors
  • shaving hairy regions
  • occlusion of hairy areas facilitates growth of microorganisms
  • high temperature & humidity
  • topical glucocorticoids
  • systemic antibiotics promotes growth of resistant organisms
  • diabetes mellitus
  • immunosuppression (systemic glucocorticoids)

Epidemiology

• inadequate water chlorination hot tub, whirlpool or less commonly, public swimming pool
• common among athletes

Pathology

* histopathology images

Clinical manifestations

• pruritic eruption
• hair follicle-centered erythematous papules with pustules
  • may look like erythematous papule with white central plug
  • may not see the hair associated with the lesion
• trunk, axilla, buttocks, & proximal extremities most commonly affected (areas with short, coarse hair)
• pubic areas, axillae, & thighs are often affected
  • can appear on any hair-bearing area of skin
• scalp commonly affected
• Pseudomonas folliculitis begins 1-4 days after bathing (hot tub etc)

* images

Laboratory

• Gram's stain
• KOH preparation for fungal hyphae
• culture of pustule
  • concern for MRSA or other drug-resistant organism
• skin biopsy

* diagnosis can be made from clinical presentation

Complications

• pseudomonas folliculitis
  • fever
  • external otitis
  • breast abscess
  • painful plantar nodules
  • bacteremia

Management

• prophylaxis
  • adequate chlorination of hot tubs & swimming pools
• general measures
  • wash with antibacterial soap, benzoyl peroxide, or chlorhexidine
• Bacterial folliculitis
  • Propionibacter acnes (see acne)
  • Staphylococcus aureus
    • mupirocin ointment BID to involved skin & nares
    • dicloxacillin 1-2 g/day divided QID for 10 days
    • cephalexin (Keflex) 1-2 g/day divided QID for 10 days
    • erythromycin 1-2 g/day divided QID for 10 days
    • minocycline 1-2 g/day divided QID for 10 days for MRSA
  • Pseudomonas aeruginosa
    • in most cases spontaneous resolution within 7-14 days
    • ciprofloxacin 500 mg BID if persistent
    • ceftazidime or cefepime for severe or prolonged cases or immunosuppressed patients
  • gram-negative folliculitis
    • discontinue current antibiotics
    • topical benzoyl peroxide
    • ampicillin 250 mg QID
    • Bactrim DS BID
    • isotretinoin
• fungal folliculitis
  • itraconazole 100 mg BID for 10-14 days (Pityrosporum, Candida)
  • terbinafine 200 mg/day (Dermatophytes)
  • fluconazole 100 mg BID for 10-14 days (Candida)
• herpetic folliculitis
  • acyclovir 400 mg TID for 7 days
  • see Herpes simplex
• Demodicidosis (Demodex) - permethrin cream

More general terms

• hair disease
• skin infection
• inflammation

More specific terms

• eosinophilic folliculitis
• Pityrosporium folliculitis

Additional terms

• pseudofolliculitis barbae; pili incarnati