A 16-year-old female presents complaining of a very itchy eruption that started quite abruptly three days ago. She recently sprained her ankle and had been soaking every night in a whirpool bath with Epsom salts to help relieve the pain.
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Folliculitis is a common and usually benign skin condition that is characterized by inflammation of the hair follicle. It can affect people of all ages and occurs in healthy, as well as immunocompromised people.
Typically, folliculitis is caused by an infection with a bacterial organism — Staphylococcus aureus being the most common culprit. Other infectious causes include dermatophytes, Candida and other gram-negative organisms such as Klebsiella, Enterobacter and Proteus. Non-infectious etiologies such as in irritant folliculitis, drug induced folliculitis or actinic folliculitis can also cause folliculitis.
Hot tub folliculitis is caused by an infection of the hair follicles with Pseudomonas aeruginosa. The characteristic clinical appearance consists of perifollicular erythematous papules vesicles or pustules, and the patient history often includes previous exposure to water. Lesions usually develop one to four days after exposure and may be pruritic or painful. The most common sites involved include the trunk, axillae, buttocks and proximal extremities.
Free chlorine levels in pools can fall especially when water temperature rises, creating an environment for bacteria such as Pseudomonas to proliferate. As such, risk factors for hot tub folliculitis include exposure to hot tubs, whirlpools or inadequately chlorinated swimming pools.
The differential diagnosis for hot tub folliculitis includes folliculitis caused by sources other than P. aeruginosa. Since folliculitis presents with erythematous papules or vesicles/pustules, it can easily be mistaken for acne, especially when found on the chest and back.
P. aeurginosa causes many other conditions such as pseudomonas hot-foot syndrome, external otitis, malignant otitis externa and ecthyma gangrenosum. The organism can also cause opportunistic infections in the hospital where it may colonize medical equipment.
Diagnosis & Treatment
Hot tub folliculitis diagnosis is usually made based on the clinical appearance of the rash and history of water exposure. The characteristic rash is perifollicular erythematous papules vesicles or pustules, which may be itchy or painful. A culture of a fresh pustule may be done to confirm the diagnosis.
Hot tub folliculitis will usually clear within seven to 14 days even without treatment. If the infection is complicated with constitutional symptoms such as fever or fatigue, it may be useful to treat with antibiotics that cover Pseudomonas. These antibiotics include certain third-generation cephalosporins such as ceftazidime, or fourth generation cephalosporins such as cefepime. Fluoroquinolones including ciprofloxacin or ofloxacin may also be useful.
Since hot tub folliculitis develops most often after exposure to Pseudomonas-infested water, prevention of infection through water filtration, automatic chlorination, maintaining a water pH between 7.2-7.8 and frequent changing of water may be beneficial. Other methods of inhibiting Pseudomonas growth include bromination and ozone ionization of the water.
James Wu, BS, is a senior medical student at Chicago Medical School at Rosalind Franklin University in Illinois.
Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine in Houston.
- Bolognia J, Jorizzo JL, Rapini RP. “Chapter 39: Folliculitis and the Follicular Occlusion Tetrad.” Dermatology. St. Louis: Mosby/Elsevier, 2008.
- James WD, Berger TD, Elston DM et al. “Chapter 14: Bacterial Infections.” Andrews’ Diseases of the Skin: Clinical Dermatology. Philadelphia: Saunders Elsevier, 2011.