What are the diagnostic criteria and treatment options for hot tub folliculitis?

Diagnosis of Hot Tub Folliculitis

Hot tub folliculitis is diagnosed clinically based on the characteristic presentation of pruritic papulopustular lesions on the trunk and extremities appearing 8-48 hours after hot tub exposure, with confirmation by bacterial culture of Pseudomonas aeruginosa from pustule specimens. 1, 2

Clinical Diagnostic Criteria

The diagnosis requires recognition of the following key features:

• Temporal relationship: Onset occurs 8-48 hours after hot tub, whirlpool, or spa pool exposure 1, 2
• Characteristic rash: Pruritic papules, papulopustules, vesicles, nodules, and occasionally urticarial lesions distributed primarily on the trunk and extremities 3, 2
• Associated symptoms: Fever, upper respiratory complaints, axillary lymphadenopathy, and breast tenderness may accompany the rash 3
• Variant presentation in children/adolescents: Painful erythematous nodules on palms or soles ("hot hand/hot foot syndrome") rather than typical truncal distribution 4

Microbiologic Confirmation

While the diagnosis can be made clinically, bacterial culture provides definitive confirmation:

• Specimen collection: Culture material from pustules or papulopustular lesions 5, 2
• Expected organism: Pseudomonas aeruginosa will grow from skin lesion cultures 3, 5, 2
• Environmental sampling: Culture of hot tub water may demonstrate the same P. aeruginosa strain, confirming the source 2

Histopathologic Features (When Biopsy Performed)

Skin biopsy is not routinely necessary but shows characteristic findings when obtained:

• Acute suppurative folliculitis with dermal abscess formation 2
• Biopsy is typically reserved for atypical presentations or when the diagnosis is uncertain 2

Critical Distinction from Hot Tub Lung

It is essential to distinguish hot tub folliculitis from MAC hypersensitivity pneumonitis ("hot tub lung"), which presents with subacute dyspnea, cough, and fever from inhaled mycobacterial antigens rather than skin lesions. 1 Hot tub lung requires:

• Compatible respiratory symptoms (dyspnea, cough) 6
• Characteristic radiographic findings (diffuse nodular infiltrates, ground glass opacities) 6
• MAC isolates from respiratory specimens and hot tub water 6
• Histopathology showing nonnecrotizing granulomas when biopsy is performed 6

Documentation Requirements

For proper clinical documentation, record:

• Exposure history: Specific timing and duration of hot tub use 1, 3
• Lesion characteristics: Distribution pattern, morphology (papules vs. pustules vs. nodules), and presence of pruritus 2
• Systemic symptoms: Fever, lymphadenopathy, or respiratory complaints 3
• Culture results: Identification of P. aeruginosa from skin lesions when obtained 5, 2
• Hot tub maintenance status: Chlorination levels and maintenance practices, as inadequate disinfection is the primary risk factor 2

Common Diagnostic Pitfalls

• Do not confuse with other folliculitides: The temporal relationship to hot tub exposure and typical distribution pattern distinguish this from staphylococcal folliculitis or other causes 2
• Recognize that the condition is self-limited: The eruption typically resolves spontaneously within 7-10 days without treatment, so extensive diagnostic workup is usually unnecessary 3, 2
• Individual susceptibility varies: Not all exposed individuals develop folliculitis, even when using the same contaminated facility 7