Human skin is prone to many types of infections from a range of microorganisms. Fungal infections of the skin are common but most are due to a type of fungus known as a dermatophyte. Yeasts are a different type of fungus that also causes infections in humans, but usually of the inner parts of the body. However, it can also infect the skin in many instances. Candida are the most likely yeasts to cause an infection inside and on the surface of the body but there may be other yeasts that are also involved. Some naturally occur on the body while others are opportunistic.
Dermatophytes vs Yeasts
It is important to understand the differences between dermatophytes and yeast.
Dermatophytes account for most fungal infections of the skin. These fungi consume the dead outer layers of the skin which are primarily made up of the protein keratin. Usually dermatophytes cannot extend beyond the most superficial layers of the skin. It has enzymes that can digest the keratin and this allows the fungus to establish itself and keep feeding on the skin. Apart from the rash and related superficial symptoms, dermatophytes do not cause deeper infections or pose a serious threat to health.
Yeasts are different. These fungi tend to reside in cavities in the human body, like within the digestive tract and vagina, and on the skin surface but do not cause an infection. The most common type of yeast, Candida albicans, is considered as part of the normal microbes that live on and in parts of the body. However, if a person’s immune system weakens then these yeasts can infect the area where it is located. Yeasts are not able to digest skin protein but if there is a cut or opening to underlying tissue then the yeast may cause an infection.
- Dermatophyte infections are known as dermatophytosis while yeast infections are usually referred to as candidiasis, names after the main yeasts to infection humans – the Candida species.
- Ringworm is a common term for a fungal infection of the skin. It is not caused by a worm but by dermatophytes (skin fungi). A ringworm infection is so named because of the ring-like skin rash that dermatophytes cause. Yeasts infections are commonly known as thrush.
- Fungal infections are not related to personal hygiene. It can affect any person. Sharing bedding, towels and even bathing in an area where these fungi may reside can lead to an infection.
- Skin fungi do not only infect the skin. It can also infect the hair and nails. It may lead to deformities of nails and loss of hair while on the skin it causes itching and rash.
Causes of Candidiasis
Candidiasis is caused by the Candida species of yeasts. This includes:
- Candida albicans (most common)
- Candida glabrata
- Candida guilliermondii
- Candida parapsilosis
- Candida tropicalis
The Malassezia species of yeasts which naturally occur on skin may also be responsible for an yeast infection of skin. It causes a widespread skin infection on the neck, arms, chest and back known as tinea veriscolor. It appears as white spots on the skin. These fungi were previously known as Pityosporum and are also implicated in conditions like dandruff. However, candidiasis specifically refers to yeast infections caused by the Candida species.
Yeasts thrive in areas that are dark, warm and moist. These three factors provide the ideal environment for fungi and can be found in many places on and in the body, like the armpits. However, yeasts in these areas will not immediately cause an infection. The barrier posed by the tough outermost layers of the skin and the defensive capabilities of the immune system prevents infections from setting in. When breaks in the skin occur, when the skin weakens significantly, when the immune system dips or if the fungi can be “changed” to become pathogenic then these relatively harmless fungi can infect the skin.
An yeast infection of the skin is more likely to occur if one or more of these risk factors are present:
- Living in a warm humid environment.
- Very young or old people.
- Diabetes mellitus.
- Immune deficient states, like in HIV/AIDS.
- Pre-existing skin diseases such as psoriasis and contact dermatitis.
- Skin injury, like chaffing with tight clothing.
- Prescription medication, like antibiotics or corticosteroids.
There are a number of other risk factors associated with candidiasis but many of these are more relevant for internal infections like oral thrush.
Angular Cheilitis (Corners of Mouth)
Angular cheilitis is a common condition that arises for a number of different reasons. An yeast infection is one possible cause. It can be acute or chronic. It is often seen in children as a result of dribbling which irritate the skin (irritant contact dermatitis). When yeast infections are the cause of angular cheilitis, there is often underlying factors like extensive oral thrush.
Also read on HIV Mouth Problems.
- Cracks at the corners of the mouth.
- Pain and tenderness at the site.
- Redness of the surrounding skin.
- Bleeding (sometimes).
Sourced from Dermatology Atlas (atlasdermatologico.com.br)
Intertrigo (Body Folds)
Intertrigo refers to any rash in the skin folds, like the armpits, between the fingers and toes, in the folds of the groin region and so on. It can be caused or worsened by yeast infections. Candidiasis in intertrigo may follow pre-existing fungal (dermatophyte/ringworm) infection in the area, other skin diseases in the folds like atopic dermatitis or with chaffing like wearing very tight underwear.
- Skin is moist, cracked and peeling.
- Itching, burning or even pain.
- Small spots, blisters or pustules.
Sourced from Dermatology Atlas (atlasdermatologico.com.br)
Diaper Rash (Buttock and Groin)
Nappy or diaper rash occurs on the buttock, groin and upper thigh area for various reasons. It often arises when a diaper is not changed often enough or if the skin is not cleaned properly after soiling. The soiled diaper containing urine and feces may then irritate the skin. An yeast infection may also cause a diaper rash on its own or be superimposed over a pre-existing rash. Infants on antibiotics early in life are prone to diaper rash caused by Candida yeasts.
- Skin redness
- Swelling just under the skin surface.
- Dryness and scaling.
- Tiny blisters.
Paronychia and Onychomycosis (Nails)
Paronychia is inflammation of the nail folds, which are the skin around the visible part of the nail (nail plate). It can be acute or chronic and an yeast infection is one possible cause. Onychomycosis is a fungal infection of the nail plate. It is a common condition that is referred to as nail fungus, or specifically fingernail or toenail fungus. It is a common problem especially among older people.
- Swelling and redness around the nail.
- Pain and tenderness (acute cases).
- Fever (acute cases).
- Nail plate distortion (chronic cases).
- Yellow or green nails (chronic cases).
- Brittle nails (chronic cases).
- Crumbling/chipping of the tips of the nails.
- Nail discoloration (yellow, white, brown, black or green).
- Lines/streaks on the nails.
- Flaking of the nail and scaling under the nail.
- Distortion of the nails.