Bacterial Folliculitis

Bacterial folliculitis is infection and inflammation centred on hair follicles, producing papules and pustules. Staphylococcus aureus is the dominant cause; Pseudomonas aeruginosa produces a distinct hot-tub-associated pattern.^[1] Few superficial pustules need only trigger removal and local care; extensive, recurrent, or refractory disease needs culture and systemic therapy. A furuncle (boil) is a deeper S. aureus infection extending suppuration into the dermis and subcutaneous tissue; interconnecting furuncles that coalesce form a carbuncle — both belong in the purulent skin-infection pathway, not this one.

Bacterial folliculitis — small papules and pustules, each centred on a hair follicle. (Da pacem Domine, CC0, Wikimedia Commons)

Typical findings

• Small erythematous papules or pustules centred on individual follicles.
• May itch, burn, or be mildly tender.
• Shaving areas, buttocks, thighs, trunk, and occluded/intertriginous areas are common sites.
• Hot-tub folliculitis appears after contaminated-water exposure and may involve areas covered by swimwear, typically 8 hours to 5 days after exposure.

• Friction, sweating, occlusion, and tight clothing.
• Shaving, waxing, or other hair removal causing follicular trauma.
• Hot-tub or pool exposure for the Pseudomonas pattern.
• Staphylococcus aureus carriage or prior recurrent staphylococcal infection.
• Diabetes, immunosuppression, or other conditions that impair host defence.

Diagnosis is usually clinical. Ask about shaving, friction, occlusion, hot-tub exposure, prior MRSA, recurrent lesions, diabetes, and immunosuppression.

Important mimics

• Pseudofolliculitis from shaving/ingrown hairs (noninfectious, induced by friction and occlusion).
• Acneiform eruptions.
• Malassezia (fungal) folliculitis.
• Hidradenitis suppurativa when recurrent painful nodules/scarring affect the axillae or groin.

• Stop formation of new pustules.
• Resolve follicular inflammation and discomfort.
• Prevent progression to furuncle, abscess, or cellulitis.
• Correct the mechanical or environmental trigger to prevent recurrence.

• Stop close shaving until inflammation resolves.
• Reduce friction, heat, occlusion, and moisture; loosen tight clothing.
• Use warm compresses and gentle cleansing.
• Do not share razors or towels.
• Launder contaminated clothing and bedding; use careful hand hygiene.

Pregnancy

Use local care first. If systemic therapy is needed, cephalexin is preferred when the organism is susceptible. Avoid routine doxycycline and trimethoprim-sulfamethoxazole when a safer effective option exists.

Immunocompromised patients

Use a lower threshold for culture, systemic therapy, and referral because disease may progress rapidly or involve unusual organisms.

Recurrent staphylococcal folliculitis

For selected patients with confirmed recurrent S. aureus disease, a decolonization course (intranasal mupirocin twice daily for 5 days plus daily chlorhexidine body wash for 5 days) may be considered.^[2]

Localized disease should stop producing new lesions within several days. Reassess at approximately 48-72 hours after starting systemic therapy, or sooner if spreading occurs. Lack of response requires culture review, reconsideration of the diagnosis, and evaluation for evolving abscess.

1. Confirm folliculitis rather than pseudofolliculitis or fungal (Malassezia) disease.
2. Confirm friction/occlusion/shaving triggers were actually removed.
3. Obtain bacterial culture if not already done.
4. Switch to susceptibility-directed therapy.
5. For recurrent S. aureus disease, assess carriage and consider a decolonization protocol.

• Giving oral antibiotics for a few uncomplicated pustules.
• Using topical antibiotics repeatedly for weeks.
• Treating hot-tub folliculitis automatically with ciprofloxacin.
• Missing a developing furuncle/abscess that requires drainage.
• Calling shaving-related pseudofolliculitis a bacterial infection.

How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.

Topical anti-staphylococcal agents

Used for localized disease after supportive measures fail.

Oral beta-lactams

First-line for extensive/refractory disease when MRSA is not a concern.

MRSA-active oral agents

Reserve for confirmed/suspected MRSA or high local MRSA prevalence.

Selected Pseudomonas coverage

Only for severe/extensive hot-tub folliculitis in a high-risk host.