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Folliculitis
is a bacterial infection of hair follicles.
Folliculitis is usually caused by Staphylococcus aureus but occasionally Pseudomonas aeruginosa (hot-tub folliculitis) or other organisms. Hot-tub folliculitis occurs because of inadequate treatment of water with chlorine or bromine.
Symptoms of folliculitis are mild pain, pruritus, or irritation. Signs of folliculitis are a superficial pustule or inflammatory nodule surrounding a hair follicle. Infected hairs easily fall out or are removed, but new papules tend to develop. Growth of stiff hairs into the skin may cause chronic low-grade irritation or inflammation that may mimic infectious folliculitis (pseudofolliculitis barbae—see Hair Disorders: Pseudofolliculitis Barbae).
Because most folliculitis is caused by S. aureus, clindamycin 1% lotion or gel may be applied topically bid for 7 to 10 days. Alternatively, benzoyl peroxide 5% wash may be used when showering for 5 to 7 days. Extensive cutaneous involvement may warrant systemic therapy (eg, cephalexin 250 to 500 mg po tid to qid for 10 days). If these measures do not result in a cure, or folliculitis recurs, pustules are Gram stained and cultured to rule out gram-negative or methicillin-resistant S. aureus (MRSA) etiology, and nares are cultured to rule out nasal staphylococcal carriage. Potassium hydroxide wet mount should be done on a plucked hair to rule out fungal folliculitis.
Treatment for MRSA usually requires two oral antibiotics, and the choice of therapeutic drugs should be based on culture and sensitivity reports.
Hot-tub folliculitis usually resolves without treatment. However, adequate chlorination of the hot tub is necessary to prevent recurrences and to protect others from infection.
Last full review/revision October 2007 by A. Damian Dhar, MD
Content last modified October 2007
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