Folliculitis


Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports

Folliculitis is defined as inflammation of the pilosebaceous unit, which can occur superficially, presenting as tender, red papules and pustules, or within the dermal portion of the follicle manifesting as abscesses and furuncles. The etiology of folliculitis can stem from both infectious and non-infectious causes. Among infectious etiologies, bacteria are common, including Gram-positive Streptococcus and Staphylococcus aureus , as well as Gram-negative Pseudomonas infections. Viral etiologies include herpes and molluscum, and fungi and yeast folliculitis can be caused by dermatophytes and Pityrosporum , respectively. Less commonly, parasitic folliculitis may be caused by agents such as Demodex , scabies, and larva migrans.

Non-infectious folliculitis can be caused by mechanical factors such as friction, occlusion, and trauma, including epilation and sunshine. Irritant folliculitis is associated with cutting oils and coal tar, while a history of significant sun exposure can trigger actinic folliculitis. Perforating folliculitis is commonly associated with diabetes mellitus and chronic renal failure. Eosinophilic pustular folliculitis can be seen in infants, immunocompromised or HIV patients, or the rarer Ofuji’s subtype. Many other inflammatory diseases are associated with sterile folliculitis, including Behçet disease, reactive arthritis, systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease, inflammatory bowel disease, lymphoproliferative disease, and pregnancy. There is a growing list of medications that can cause folliculitis including lithium, halogens, corticosteroids (both topically and systemically), androgens, ACTH, isoniazid, phenytoin, and sirolimus. Immune-targeted therapy is a category of medications that cause folliculitis as a side effect, including epidermal growth factor receptor (EGFR) inhibitors, tumor necrosis factor-alpha (TNF-α) inhibitors, trastuzumab, sorafenib, vemurafenib, and dabrafenib.

A thorough history and physical examination are crucial to highlight the most likely etiology in each case. Prolonged antibiotic used in acne patients, particularly tetracycline use, is associated with the development of Gram-negative folliculitis, caused by Pseudomonas and other similar bacteria. Exposure to contaminated pools or Jacuzzis are frequent sources of Pseudomonas folliculitis. Pityrosporum folliculitis is seen commonly in young adults as pruritic perifollicular papules on the upper trunk, often in warm climates or seasons.

Management Strategy

Once the etiology of the folliculitis is ascertained, infectious folliculitis is best managed with a pathogen-direct antimicrobial regimen . Therapeutic options include antiseptics and topical or systemic antibiotics for bacterial folliculitis. Coverage for methicillin-resistant Staphylococcus aureus (MRSA) should be considered in high-risk patients, pending culture sensitivities. For viral, fungal, yeast, and parasitic folliculitis, targeted therapy as appropriate is suitable. Mechanically induced folliculitis often improves with removal of the precipitant. Eosinophilic folliculitis is responsive to phototherapy, and folliculitis related to underlying inflammatory conditions often improves with treatment of primary disease.

Specific Investigations

  • Physical examination and past medical history with particular focus on medication usage, concurrent diseases, sun exposure, and family history

  • Bacterial, fungal, or viral culture and polymerase chain reaction (PCR) methods with drug sensitivity testing

  • Gram stain, Tzanck smear, potassium hydroxide (KOH) preparation

  • Tissue biopsy for histologic examination with microorganism stains

  • Complete blood count, workup for immunodeficiencies, blood chemistries, renal function test, HIV status

  • Nasal culture in chronic or recurrent bacterial cases

First-Line Therapies

Topical therapy
  • Mupirocin, clindamycin, and retapamulin for S. aureus

  • A

  • Mupirocin for decolonization of S. aureus of the nares

  • A

  • Daily chlorhexidine or tea tree oil soap body wash for recurrent Staphylococcus spp.

  • B

  • Selenium sulfide shampoo or propylene glycol for Pityrosporum spp.

  • C

  • Permethrin or metronidazole for Demodex spp.

  • A

  • Topical adapalene as prophylaxis for actinic folliculitis

  • D

  • Corticosteroid or tacrolimus for eosinophilic pustular folliculitis

  • C, D

Oral therapy
  • Dicloxacillin or cephalexin for β-hemolytic streptococci or methicillin-sensitive S. aureus (MSSA)

  • B

  • Trimethoprim/sulfamethoxazole, clindamycin, doxycycline, or linezolid for MRSA

  • B

  • Ciprofloxacin for Pseudomonas

  • C

  • Ampicillin, trimethoprim/sulfamethoxazole, or ciprofloxacin for Gram-negative bacteria

  • B

  • Itraconazole or fluconazole for Pityrosporum spp.

  • A

  • Aciclovir, valaciclovir, or famciclovir for herpes

  • A

  • Ivermectin and metronidazole (combination therapy) for Demodex spp.

  • A, B

  • Ivermectin for Demodex spp.

  • D

  • Indomethacin or ciclosporin for eosinophilic pustular folliculitis

  • C

  • Tetracycline for EGFR inhibitor–induced folliculitis

  • B

Facial bacterial infections: folliculitis

Laureano AC, Schwartz RA, Cohen PJ. Clin Dermatol 2014; 32: 711–4.

Dicloxacillin (250–500 mg four times per day) or cephalexin (250–500 mg four times per day) for 7–10 days is usually sufficient in eradicating conventional facial folliculitis.

Topical retapamulin ointment, 1%, versus sodium fusidate ointment, 2%, for impetigo: a randomized, observer-blinded, noninferiority study

Oranje AP, Chosidow O, Sacchidanand S, et al. Dermatology 2007; 215: 331–40.

Retapamulin was equally efficacious with sodium fusidate in the topical treatment of superficial skin infections.

Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America

Stevens DL, Bisno AL, Chambers HF, et al. Clin Infect Dis July 15, 2014; 59: e10–52.

The expert panel’s recommendations include a decolonization regimen of 5 days of topical mupirocin and daily chlorhexidine body washes plus daily decontamination of personal items to prevent recurrences.

How resistant is Staphylococcus aureus to the topical antibiotic mupirocin?

Rakshit, T, Suchitra S. Journal of Global Antimicrobial Resistance 2017; 8; 102–3.

Authors express concern for low- and high-level mupirocin resistance in MRSA but, in a prospective study of 405 cases of MRSA, found no evidence of resistance at a tertiary care hospital in India.

Treatment of MRSA soft tissue infections: an overview

Morgan M. Injury 2011; 42: S11–7.

Suggested antimicrobials for folliculitis include cotrimoxazole, clindamycin, doxycycline, linezolid, rifampicin, and fusidic acid.

Community-acquired methicillin-resistant Staphylococcus aureus skin infections: implications for patients and practitioners

Cohen PR. Am J Clin Dermatol 2007; 8: 259–70.

A 10- to 14-day course of oral trimethoprim/sulfamethoxazole (1–2 tablets twice daily), clindamycin (300–450 mg four times per day), or doxycycline (100 mg twice daily) is most useful.

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