Every hair on the human body grows from a hair follicle and
infections of the hair follicle can exhibit various clinical
presentations.
Folliculitis is an inflammatory reaction in the superficial
aspect of the hair follicle and can involve the follicular opening
or the perifollicular hair follicles. To appreciate this better,
familiarity with the structure of the hair follicle is necessary.
The pilosebaceous unit of the follicle is divided into three
main parts: the infundibulum (superficial part, outlined by
the sebaceous duct), the isthmus (the middle segment between
the sebaceous duct and arrector pili bulge), and the inferior
segment (stem and hair bulb). When there is an inflammatory
reaction in the superficial part of the hair follicle, it is
known as a folliculitis. Folliculitis starts when hair follicles
are damaged by friction from clothing, occlusion or blockage
of the follicle, physical injury, chemical irritation or infection.
Folliculitis can be divided into two major categories on the
basis of histological location: superficial and deep. The
depth of involvement determines whether the folliculitis
is superficial
or deep. The most common form of folliculitis is a superficial
folliculitis that is seen as a tender or painless pustule
(a small swelling similar to a blister or pimple) that heals
without
scarring. Most often, the hair shaft will be seen within the
pustule. Typically, superficial folliculitis is caused by
the pathogen, S. Aureus, and is bacterial rather than mechanical
in nature. The condition presents as minute erythematous (reddened)
follicular pustules without involvement of the surrounding
skin.
The scalp, neck, trunk, buttocks and extremities are favorite
sites of involvement.
In deep folliculitis, infection extends deep into the follicle,
affecting either the entire follicle or the deeper portion
of the follicle. The resultant inflammation and reddening
with
or without pustules is more pronounced than that seen in
superficial folliculitis. The lesions are painful and may
scar.
Gram-negative folliculitis is a kind of deep folliculitis
that sometimes develops in people receiving long-term
antibiotic treatment for acne. The pathogens identified
include Klebsiella,
Enterobacter, and Proteus species. Antibiotics used routinely
in the therapy of acne alter the normal balance of bacteria
in the nose, leading to an overgrowth of harmful organisms
(Gram-negative
bacteria). In most people, this does not have any significant
side effects. However, in some cases Gram-negative bacteria
spreads to the cheeks, chin and jaw line, where they cause
new and severe acne lesions.
Hot Tub Folliculitis is a condition caused by Pseudomonas
aeruginosa, and is often seen where spa sanitation is
at fault. Pseudomonas
survives in hot water unless the pH and chlorine content
are strictly controlled and are commonly found in contaminated
whirlpools, hot tubs, water slides and physiotherapy
pools. The infection
is manifested within 6 to 72 hours after exposure as
multiple pustular or perifollicular lesions on the trunk
and extremities.
This may be accompanied by fever and malaise.
Folliculitis
clinical features
Clinically, the inflammation of folliculitis manifests as
1mm-wide vesicles (circumscribed elevation of the skin containing
serum), or as pustules (a collection of pus formed by tissue
destruction), or papulo-pustules in acute cases. However,
in chronic cases there may also be hyperkeratosis (abnormal
hardening) and keratotic plug formations. The presence of
superficial pustules does not always imply an infectious origin,
as there are many noninfectious types of folliculitis as well.
Follicular pimples can be distinguished from acne as in case
of folliculitis, often the hair shaft can be seen at the center
of the lesion. It is also important to understand that there
are some skin diseases with follicular expression, such as
atopic dermatitis or psoriasis.
Lesions of superficial folliculitis typically resolve spontaneously.
Topical therapy with erythromycin, clindamycin, mupirocin, or
benzoyl peroxide helps accelerate recovery. In the treatment
of deep folliculitis, oral antibiotics are usually used. Due
to their efficacy and safety profiles, first generation cephalosporins
are one of the most widely used classes of antibiotic agents
used. Others include penicillinase–resistant penicillins,
macrolides and fluoroquinolones.
Lesions of hot tub folliculitis normally resolve themselves
spontaneously within 7-10 days, and do not require specific
treatment. In this condition, prevention is better than cure
and treatment is directed towards the facilities that are suspected
to have the water contamination. Treatment of Gram-negative
folliculitis involves the identification and elimination of
the source of the Gram-negative infection. The condition can
be treated with isotretinoin, a chemical compound which acts
by inhibiting the secretion of sebum. The side effects of the
use of isotretinoin must be considered before commencing treatment.
