Fungal Skin Infections
Fungi are found everywhere and yeasts form part of the normal skin flora. Fungal
infections of the skin, hair and nails are common skin diseases. Fungi can
infect the skin of people of all ages. Increased incidence occurs in
immunocompromised patients who have AIDS or are being treated with
chemotherapeutic agents and therapy directed at reducing inflammation. People
with diabetes and people who are simply getting older have more infections.
Skin infections can be divided into the most common superficial group that stays
in the outer layers of the skin and an invasive group that extends beyond the
skin in adjacent tissues and spread to other organs. Invasive skin infections
such as blastomycosis often develop after a primary lung infection is
established. The infecting yeast travel in the blood from the lung to skin
areas. See Blastomycosis of the Skin.
Candida infection occur in damp areas, in any skin fold, in the groin, around
the anus and vagina. The skin becomes itchy, painful and red. Women often
develop candidal vulvovaginitis with white plaques developing inside on a
swollen, red vaginal mucosa with a creamy vaginal discharge; The surrounding
skin becomes red and sore; sometimes pustules develop on the vulvar skin.
Male sex partners often develop skin infections involving the penis, scrotum and
groin. Candida can infect nails and the tissue surrounding the nail (paronychia).
Swelling with pain of the nail fold can become chronic with nail involvement.
The nail develops yellowish discoloration and may separate from the nail bed.
More about Candida
Malassezia includes nine species, eight of which have been recovered from
Tinea versicolor (pityriasis versicolor) is a yeast infection that changes
the pigmentation of the skin but is otherwise assymptomatic. Blotches of darker
skin in light-skinned patients; areas of light pigmentation appear in patients
with dark skin. The yeasts also can grow in hair follicles causing inflammation
with red papules and pustules that surround individual hairs. Treatment with
selenium sulfide shampoo (Selsun) is usually helpful. The shampoo is applied to
the affected skin and allowed to dry for 15 minutes and then washed off. This
routine can be repeated weekly as required to prevent recurrence. Seborrheic
dermatitis involving the scalp causes dandruff and may be a lifelong problem
that can be controlled with regular use of selenium sulfide shampoo and/or
Dermatomycoses are caused by filamentous fungi such as Trichophyton,
Microsporum or Epidermophyton.
Tinea pedis is fungal infection of the feet (athletes foot), the most common
skin fungal infections that affect 70% or more of the adult population
Tinea capitis is a scalp infection with trichophyton tonsurans and violaceum
or microsporum canis, primarily affecting prepubescent children.
Tinea gladiatorum was named after fungal infections of the face, neck and
shoulders become common in high school wrestlers. often caused by Trichophyton
Ringworm infections (tinea corporis and tinea cruris). There are
expanding ring lesions, not caused by worms. Fungi infect the skin. Tinea
corporis is usually a scaly plaque with a red ring border and central clearing;
this is caused by Trichophyton rubrum, Trichophyton tonsurans, Trichophyton
mentagrophytes and Microsporum canis. The fungus can be transmitted from other
humans, cats and dogs. Trichophyton rubrum may first infect the feet and spread
to other parts of the body.
Onychomycosis is a fungal infection affecting the nail bed
and nail plate requires treatment with oral antifungal agents. Toenails are more
often involved than finger nails. White crumbly areas on the nail surface, (T.
mentagrophytes) and abnormal color are the main signs of infection. Nail
involvement often accompanies skin fungal infection.
Some fatty acids are toxic to fungi. Undecanoic acid, an eleven carbon fatty
acid, is most toxic to fungi growing in culture and has been available for many
years as a treatment for skin fungal infections (as Desenex).
Three types of inhibitors of the ergosterol biosynthetic pathway are
effective in suppressing the growth of skin fungi:
1 Azoles (e.g. topical miconazole and topical/oral ketoconazole, itraconazole
2. Allylamines (e.g. terbinafine)
3 Morpholines (amorolfine).
A Cochrane review of topical skin treatment for fungal infection concluded
that allylamines, azoles and undecenoic acid were efficacious. Allylamines cure
slightly more infections than azoles but are much more expensive. The most cost
– effective strategy is first to treat with azoles or undecenoic acid and to use
allylamines only if that fails.
Skin infection with blastomycosis.
Early lesions are nonpainful papules, nodules, or plaques that develop
drainage areas in the middle of the lesion. In immunocompromised patients
multiple acute pustular lesions appear in the context of an acute systemic
illness. Disseminated blastomycosis can appear in any part of the body:
prostatitis, peritonitis, osteomyelitis, septic arthritis, laryngeal and brain
involvement have been reported.
Azole Drug Example
Miconazole nitrate is used topically for the treatment of tinea pedis, tinea
cruris, and tinea corporis caused by T. mentagrophytes, T. rubrum, or
Epidermophyton floccosum and for the treatment of cutaneous candidiasis
(moniliasis). Tinea corporis and tinea cruris generally can be effectively
treated using a topical antifungal; however, an oral antifungal may be necessary
if the disease is extensive, dermatophyte folliculitis is present, the infection
is chronic or does not respond to topical therapy, or the patient is
immunocompromised because of coexisting disease or concomitant therapy. While
topical antifungals usually are effective for the treatment of uncomplicated
tinea manuum and tinea pedis, an oral antifungal usually is necessary for the
treatment of hyperkeratotic areas on the palms and soles, for chronic
moccasin-type (dry-type) tinea pedis, and for the treatment of tinea unguium
Topical agents available as non-prescription self medications include:
miconazole, clotrimazole, terbinafine, tolnaftate, naftifine, ciclopirox,
ketoconazole, econazole, oxiconazole, butenafine, or sulconazole.
Fungal skin infections and other common disorders are discussed in the the
Skin in Health and Disease by Stephen Gislason MD.
Hirschmann, Jan V, 2 Dermatology, VII Fungal, Bacterial, and Viral Infections
of the Skin, ACP Medicine Online, Dale DC; Federman DD, Eds. WebMD Inc., New
York, 2000. http://www.acpmedicine.com/
Gupta AK ; Cooper EA ; Ryder JE ; Nicol KA ; Chow M ; Chaudhry MM. Optimal
management of fungal infections of the skin, hair, and nails. Am J Clin
Dermatol. 2004; 5(4):225-37 (ISSN: 1175-0561)
Borgers M ; Degreef H ; Cauwenbergh G. Fungal infections of the skin: infection
process and antimycotic therapy. Curr Drug Targets. 2005; 6(8):849-62
Crawford F ; Hart R ; Bell-Syer S ; Torgerson D ; Young P ; Russell I. Topical
treatments for fungal infections of the skin and nails of the foot. Cochrane
Database Syst Rev. 2000; (2):CD001434 (ISSN: 1469-493X)