2.2.4 Folliculitis

Usually Staphylococcus aureus (coagulase positive), but also gram-negative bacteria or Malassezia spp. and other mycotic species are in most cases to be discovered in the acro- and the infra- infundibulum of hair follicles. However, sebaceous gland follicles and vellus hair follicles are often also involved.

Predisposing factors are in particular: mechanical pressure, tight clothing, excoriations, increased humidity and sweating, occlusion by topical products or wound dressings, terminal hair shaving, local and systemic immunosuppression (topical and systemic corticosteroids; HIV, diabetes mellitus, ciclosporin) and finally inadequate hygiene, poverty and nutrition deficiency.

1. Ostiofolliculitis (Bockhart): pyoderma of the follicle ostia; often in intertriginous or occluded areas.

2. Folliculitis et perifolliculitis: deeper penetration of infection into the infrainfundibulum with stronger inflammatory reaction and marked perifolliculitis. Final stage with deeper penetration leads to furuncle and involvement of several follicles to carbuncle.

3. Folliculitis barbae: chronic ostiofolliculitis of terminal hair in the beard area, often further spread by shaving.

4. Folliculitis decalvans: late stage of chronic folliculitis of the scalp; uncommon chronic folliculitis with scarring alopecia (pseudopelade), bundles of hairs (tufting).

5. Perifolliculitis capitis abscedens et suffodiens: probably maximal variant of folliculitis decalvans capilliti.

In patients with immunodeficiency, diabetes mellitus, kidney dialysis patients, long term topical and systemic antibiotic treatment and non-responders to standard treatments, a culture with classification and resistogram is essential.

Usually, the follicle orientated clinical features make the diagnosis. A classification by culture of the microbial agent may help in addition to differentiate for example a bacterial or mycotic pustular eruption or mixed types or exclusion of gram-negative microbes. On the scalp a biopsy may also be helpful.

Other forms of folliculitis with sterile and non-sterile pustules and intra – or interfollicular localization:

Often:

• Pseudofolliculitis barbae: pili recurvati or incarnati with secondary foreign body reaction.

• Drug induced pustular eruption.

• Coxsackie, Varicella and Herpes disseminating vesiculopustules

Rare:

• eosinophilic folliculitis;

• pustular psoriasis;

• perforating folliculitis;

• acrosyringeal pustular eruption;

• Myeloid blast cell dissemination to the skin.

Depending on severity and location, first choice is always the application of antiseptics. One should avoid topical antibiotics because of inducing resistant strains and inducing spread of those strains (community). Identification of nasal carrier of gram-negative bacteria is necessary and according to testing, specific antibiotics are allowed (mupirocin, ozenoxacin).

Systemic antibiotics in case of deep disseminated folliculitis and perifolliculitis or developing of multiple furuncle/carbuncle should always be considered.

Topical antimycotics are to be used when positive in microscopy, culture or immunofluorescence / PCR. In deep penetrating and /or widespread mycotic infection, systemic azoles are essential.

Prevention by change and washing of clothing regularly in predisposed and in infected patients is mandatory. Patients should avoid humidity and be educated not to over-wash the skin (ph-neutral or acidic shower gels).