Folliculitis is an infection of hair follicles.
(See also Overview of Bacterial Skin Infections.)
The etiology of folliculitis is often unclear, but perspiration, trauma, friction, and occlusion of the skin are known to potentiate infection. The pathogen may be bacterial, fungal, viral, or parasitic. Bacterial folliculitis is usually caused by Staphylococcus aureus, but occasionally Pseudomonas aeruginosa (hot tub folliculitis) or other organisms have been reported. Hot tub folliculitis occurs because of inadequate chemical treatment of water. Acne is a noninfectious form of folliculitis.
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).
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.
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.
Folliculitis can be caused by various pathogens and tends to be potentiated by perspiration, trauma, friction, and occlusion of the skin.
Bacterial folliculitis is usually caused by Staphylococcus aureus, but occasionally Pseudomonas aeruginosa (hot tub folliculitis).
Treat staphylococcal folliculitis with clindamycin 1% lotion or gel.