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Types of folliculitis introduction
Bacterial folliculitis
Fungal folliculitis
Viral folliculitis
Parasitic folliculitis
Types of folliculitis references
Types
of folliculitis introduction
Every hair on the human body grows from a follicle,
a shaft or opening on the surface of the skin. Although follicles
are densest on the scalp, they are also present everywhere except
on the palms, soles and mucous membranes. The pilosebaceous
unit of the follicle is divided into three parts, the infundibulum
or the superficial part including the sebaceous gland, the isthmus
(middle segment) and the inferior part, which comprises of the
stem and hair bulb. Normally, the follicles carry out their
functions with few problems, but when they are damaged, or invaded
by viruses, bacteria or fungi, it leads to infections and folliculitis.
The term folliculitis is used to describe inflammatory reaction
in the superficial aspect of the hair follicle.
In order to simplify the broad spectrum of Folliculitis, the
condition is classified into infectious folliculitis and non-infectious
folliculitis, based on clinical manifestations and therapeutic
applications. Based on the causative agent, infectious folliculitis
is further classified as:
-
Bacterial Folliculitis
-
Fungal Folliculitis
-
Viral Folliculitis
-
Parasitic Folliculitis
Bacterial
folliculitis
Bacterial Folliculitis develops when bacteria, usually one
from the Staphylococcus family of bacteria, enter the body
through a cut, scrape, surgical incision, or other break in
the skin
near a hair follicle. The bacteria can get trapped and the
infection may spread to hair follicles on other parts of the
body.
Bacterial folliculitis may be superficial or deep. Superficial
folliculitis, also called impetigo, consists of pustules, which
are small-circumscribed elevations of the skin, containing purulent
material. The pustules are often surrounded by a ring of redness
located within follicular orifices. If the infection of the
follicle goes deeper and involves more follicles, it is considered
as deep folliculitis and the condition can present as furuncles
and carbuncles. These are more serious than folliculitis and
can cause permanent damage and scarring.
A furuncle is a tender, erythematous, firm or fluctuant mass
of walled-off purulent material, arising from the hair follicle,
occurring as a result of the spread of the bacterial infection
deeper into the tissues of the follicles, beneath the infundibulum.
Carbuncles are an aggregate of furuncles that form broad, swollen,
erythematous, deep, and painful masses that usually open and
drain through multiple tracts. The pus formation in carbuncles
is more deeply seated than in the case of furuncles. Necrosis
(death) of the intervening skin occurs, and a nodule with a
central crater may be seen.
Bacterial folliculitis usually occurs in children or adults
with a predisposing factor that helps to increase the number
of bacteria present on the skin. Staphylococcus Aureus is the
most common causative agent, and species of streptococcus, pseudomonas,
proteus, and coliform bacteria have also been implicated as
causes of bacterial folliculitis.
“Hot Tub” Folliculitis is a condition caused by
the pathogen Pseudomonas aeruginosa, and is often seen where
spa sanitation is at fault. Bacterial Sycosis is another deep,
chronic staphylococcal infection that involves the entire hair
follicle. The pathogens identified in Gram-negative folliculitis
include Klebsiella, Enterobacter, and Proteus species. This
type of folliculitis sometimes develops in people receiving
long-term antibiotic treatment for acne.
Various types of cutaneous
lesions typically present themselves in secondary stages of
syphilis, a chronic infectious disease
caused by Treponema pallidum. The lesions usually present
as papules or pustules. Papules are small, circumscribed, solid
elevation on the skin, less than 0.5 cm. Acneiform syphilis
is a type of granulomatous perifolliculitis in late stages
of
syphilis with lesions that appear as ring-shaped papules or
solid, raised bumps called nodules.
Some superficial follicle infections spontaneously resolve
themselves. However, bacterial infections like impetigo, furuncles,
carbuncles and “hot tub” folliculitis may not
resolve spontaneously and generally require prescription therapy.
All
these infections are typically diagnosed by clinical presentation,
and predisposing factors need to be identified and eliminated.
-
Superficial bacterial folliculitis usually responds
to topical antibacterial agents such as mupirocin or fusidic
acid ointment.
-
When antibiotics are required, one that is
active against gram-positive organisms such as penicillinase-resistant
penicillins,
or broad-spectrum antibiotics like cephalosporins, macrolides, or fluoroquinolones
is usually chosen.
-
If furuncles and carbuncles do not
rupture on their own, then they require incision and drainage
(lancing).
-
Children, patients who have diabetes, or
patients who have immunodeficiencies, are more susceptible
to gram-negative
infections and may
require treatment with a second- or third-generation cephalosporin.
Fungal
folliculitis
Superficial fungal infections are found in the top layers
of the skin; deep fungal infections invade deeper layers of
the skin and hair follicles and can spread to the blood or
internal organs. According to the infected body area, fungal
folliculitis can be classified as tinea capitis (scalp), tinea
barbae (beard), tinea corporis (trunk), tinea cruris (groin)
and tinea pedis (feet). Fungal infection in or on a part of
the body can be divided essentially into three groups: dermatophytic,
pityrosporum and candida folliculitis.
Dermatophytic folliculitis is caused most often by a zoophilic
species, i.e. fungal species that show attraction to or affinity
for animals; and the condition presents as follicular pustules
surmounting a hardened erythematous (reddened) plaque with
peripheral extension. The degree of inflammation is dependant
on the depth of fungal penetration, which in turn determines
the extent of hair shaft loss.
Tinea capitis or ringworm of the head is the most important
form of pediatric dermatophytic folliculitis, and has four
basic variants – non-inflammatory, black dot, favus
and kerion. In the first two forms, there is minimal inflammation
and no scarring, whereas the latter two forms present with
severe granulomatous and suppurative folliculitis and permanent
hair loss.
The clinical features of tinea capitis vary considerably
depending on the species responsible for the infection. Typically,
there is partial alopecia with a varying amount of inflammation.
In the non-inflammatory variants, asymmetrical lesions with
short broken hair, 1 to 3 mm in length, are observed. Slight
inflammation with scaling may be observed on careful inspection.
Infection with the zoophilic species tends to produce small
lesions with intense inflammation. The most severe inflammatory
reactions are called kerion and produce painful boggy masses
studded with pustules. These lesions can result in severe
hair loss and significant scarring when the disease is in
advanced stages.
Tinea capitis must be differentiated from seborrheic dermatitis,
atopic eczema, psoriasis, alopecia areata, folliculitis, and
pseudopelade. The diagnosis of tinea capitis is established
by identifying the organism in infected hairs under the microscope.
Cultures should be obtained to confirm the diagnosis.
Tinea capitis does not respond to topical antifungal agents.
Griseofulvin is an effective drug and should be administered
depending on the age of the patient. Administration of Terbinafine
has also shown efficacy.
Tinea barbae is a superficial dermatophytic infection that
is limited to the bearded areas of the face and neck and occurs
almost exclusively in older adolescent and adult males. The
clinical presentation of tinea barbae includes deep folliculitis,
red inflammatory papules and pustules with exudation, crusting
and associated hair shaft loss. The two main species causing
the infection are T. mentagrophytes and T. verrucosum.
Kerion and favus are deep suppurative types of folliculitis
affecting the scalp. Complications may include pain, fever,
and scarring and permanent hair loss. In such cases, oral
therapy with Griseofulvin and terbinafine is necessary.
Pityrosporum Folliculitis is a condition caused by pityrosporum
yeasts, most often Pityrosporum orbiculare, where the yeast
gets down into the hair follicles and multiplies, resulting
in an itchy eruption. The lesions are reddish follicular papules
and pustules located mainly on the upper back, shoulders and
chest. The condition responds to treatment with a topical
antifungal agent.
Candida folliculitis is folliculitis caused by the Candida
species, ubiquitous fungi that most commonly affect humans.
Candida folliculitis must be treated with oral itraconazole,
a broad-spectrum antifungal agent.
Viral folliculitis is an infrequently reported entity involving
a variety of viral infections limited to the hair follicle.
The clinical presentation of folliculitis caused by the herpes
simple virus (HSV) appears as clustered vesicles (small circumscribed
elevation of the skin containing serum) on an erythematous (reddened)
base. They often progress to form pustular or ulcerated lesions,
and eventually a crust. Cases caused by molluscum contagiosum
maybe considered a sign of immunosuppression, and the condition
manifests as multiple whitish, itchy papules over the beard
area. There are also some reports of folliculitis caused by
herpes zoster infection.
The recommended treatment for viral herpetic folliculitis entails
administration of oral antihistamines. There is no single perfect
treatment for infection by molluscum contagiosum, and scraping
off the bumps using a tool called a curette is a common way
to surgically remove them.
Parasitic
folliculitis
Parasites causing folliculitis are usually small pathogens
that burrow into the hair follicle to live there or lay their
eggs. Mites such as Demodex folliculorum and Demodex brevis
are natural hosts of the human pilo-sebaceous follicle. The
spectrum of the skin disorders due to these parasites includes:
-
Follicular pityriasis (skin disease characterized
by epidermal shedding of flaky scales)
-
Eruptions of the
scalp with or without pus
-
Acne rosacea (a chronic dermatitis
of the face characterized by a red or rosy coloration
with deep-seated papules and
pustules)
-
Some cases of blepharitis (inflammation
of the eyelids)
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Perioral dermatitis
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Pustular folliculitis
-
Hyper-pigmented
plaques
All these conditions show rapid response to topical permethrin
cream (a topical insecticide used to treat mites) or systemic
ivermectin or itraconazole (a broad-spectrum antifungal agent).
Types
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