Fungal Infections

Superficial Fugal Infections

Dermatophytes:ringworm

Candidal spectrum:candidasis

Pitryosporum:pitrysisversicolor

Dermatophyte infectionscutaneous lesions due to dermatophytes presenting most commonly as: athelet’s foot,nail infections,tinea corporis and scalp ring worm.

Tinea Pedis

term used for a dermatophyte infection of the soles of the feet and the interdigital spaces

Patients with tinea pedis have the following 4 possible clinical presentations:

1- Interdigital tinea pedis

2- Chronic hyperkeratotic tinea pedis

The interdigital presentation is the most characteristic type of tinea pedis, with erythema, maceration, fissuring, and scaling, most often seen between the fourth and fifth toes. This type is often accompanied by pruritus.

The hyperkeratotic type of tinea pedis is characterized by chronic plantar erythema with slight scaling to diffuse hyperkeratosis.

This type is also called moccasin tinea pedis

3- Inflammatory/vesicular tinea pedis

4- Ulcerative tinea pedis

Painful, pruritic vesicles or bullae, most often on the instep or anterior plantar surface, characterize the inflammatory/vesicular type

The ulcerative variety is characterized by rapidly spreading vesiculopustular lesions, ulcers, and erosions, typically in the web spaces, and is often accompanied by a secondary bacterial infection.

Nail infection

1- Distal subungal 2- Proximal subungal3- White superficial4- Candida onychomycosis

Tinea Corporis

Tinea corporis is a superficial dermatophyte infection characterized by either inflammatory or noninflammatory lesions on the glabrous skin (ie, skin regions except the scalp, groin, palms, and soles).

Tinea Capitis

Clinical presentation of tinea capitis varies from a scaly noninflamed dermatosis resembling seborrheic dermatitis to an inflammatory disease with scaly erythematous lesions

hair loss or alopecia that may progress to severely inflamed deep abscesses termed kerion, with the potential for scarring and permanent alopecia

Favus (also termed tinea favosa) is a severe form of tinea capitis

Scalp lesions are characterized by the presence of yellow cup-shaped crusts termed scutula, which surround the infected hair follicle.

Black dot tinea capitis refers to an infection with fracture of the hair, leaving the infected dark stubs visible in the follicular orifices

Laboratory diagnosis of tinea capitis depends on examination and culture of skin rubbings, skin scrapings, or hair pluckings (epilated hair) from lesions.

Selected hair samples are cultured or allowed to soften in 10-20% potassium hydroxide (KOH) before examination under the microscope. Examination of KOH preparations (KOH mount) usually determines the proper diagnosis if a tinea infection exists

Wood lamp examination

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Wood lamp examination:

Light is filtered through a Wood nickel oxide glass (barium silicate with nickel oxide), which allows only the long ultraviolet rays to pass (peak at 365 nm).

Skin biopsy

endoectothrix invasion of a hair shaft by Microsporum audouinii. Intrapilary hyphae and spores around the hair shaft are seen

Treatment

Choice of treatment for tinea capitis is determined by the species of fungus concerned, the degree of inflammation

Systemic treatment is indicated if:1. Disease involve hair or nails.2. More than one site is involved.3. Lesions are extensive.4. Topical treament has already failed.

Pitrysis Versicolor

a common, benign, superficial cutaneous fungal infection usually characterized by hypopigmented or hyperpigmented macules and patches on the chest and the back

Pitrysis versicolor is caused by the dimorphic, lipophilic organisms in the genus Malassezia, formerly known as Pityrosporum

The organism can be found on healthy skin

The organism can be found on healthy skin and on skin regions demonstrating cutaneous disease. In patients with clinical disease, the organism is found in both the yeast (spore) stage and the filamentous (hyphal) form.

Factors that lead to the conversion of the saprophytic yeast to the parasitic, mycelial morphologic form include a genetic predisposition; warm, humid environments; immunosuppression; malnutrition; and Cushing disease.

The skin of an individual who is affected by tinea versicolor may be either hypopigmented or hyperpigmented. In the case of hypopigmentation, tyrosinase inhibitorscompetitively inhibit a necessary enzyme of melanocyte pigment formation

(resulting from the inhibitory action of tyrosinase of dicarboxylic acids formed through the oxidation of some unsaturated fatty acids of skin surface lipids)

In hyperpigmented macules in tinea versicolor, the organism induces an enlargement of melanosomes made by melanocytes at the basal layer of the epidermis.

Candidiasis

Candidiasis

Candidosis is an infection caused by the yeast Candida albicans or other Candida species. C albicans, the principal infectious agent in human infection, is an oval yeast 2-6 µm in diameter

candidal infection of the skin has increased in prevalence in recent years, principally because of the increased numbers of patients who are immunocompromised

Humans carry yeast fungi, including candidal species, throughout the gastrointestinal tract (mouth through anus) as part of the normal commensal flora.

The vagina also commonly is colonized by yeast (13% of women), most commonly by C albicans and C glabrata

The commensal oral isolation of candidal species ranges from 30-60% in healthy adults. Note that Candida species are not part of the normal flora of the skin; however, they may colonize fingers or body folds transiently.

Causes

Host factors that predispose patients to infections are numerous.

Local factors such as tissue damage resulting from trauma, xerostomia, radiation-induced mucositis

ulcerations, skin maceration, or occlusion enhances adhesion and predisposes patients to increased infection rates.

Endocrine diseases such as diabetes mellitus, Cushing syndrome, hypoparathyroidism, hypothyroidism, and polyendocrinopathy

The mechanism by which diabetes mellitus is believed to raise infection rates is through increased tissue glucose, altered yeast adhesion, and decreased phagocytosis

Nutritional deficiencies may alter host defense mechanisms or epithelial barrier integrity, allowing increased adherence or penetration.

Iron deficiency anemia and deficiencies including vitamins B1, B2, B6, C, and folic acid are associated with heightened infection rates.

Oral candidiasis in adults: Use of broad-spectrum antibiotics and inhaled corticosteroids, diminished cell-mediated immunity, and xerostomia are all risk factors for candidiasis

Ecologic balance disruption: Under normal circumstances, it appears unlikely that candidal organisms establish in the mouths of noncarriers; however

if the ecologic balance is altered (by bacterial suppression, alteration of salivary flow, or immunologic deficit), candidal infection may occur

Clinical

Candidal vulvovaginitis: This common condition in women presents with itching, soreness, and a thick creamy white discharge

Candidal diaper dermatitis (CDD):

Infected stools represent the most important focus for cutaneous infection. Moist macerated skin is particularly susceptible to invasion by C albicans

Additional factors that predispose infants to CDD include local irritation of the skin by friction; ammonia from bacterial breakdown of urea, intestinal enzymes, and stool; detergents; and disinfectants

Intertrigo: Most cases of cutaneous candidosis occur in skin folds where occlusion (by clothing or shoes) produces abnormally moist conditions

Sites such as the perineum, mouth, and anus, in which Candida organisms normally may be carried, are at further risk of infection.

Candidal infection of the skin under the breasts or pannus occurs when those areas become macerated

Paronychia: Candida organisms occasionally cause infection in the periungual area and underneath the nailbed

Disease is more common in people who frequently submerge their hands in water and usually is not associated with the elderly population. One important exception to this generalization is the population of patients with diabetes.

Oropharyngeal candidiasis (OPC):

The most common clinical appearance of OPC (pseudomembranous candidosis or oral thrush) in the adult population occurs as white plaques

that are present on the buccal, palatal, or oropharyngeal mucosa overlying areas of mucosal erythema. Typically, the lesions are removed easily and may demonstrate areas with tiny ulcerations

OPC in the neonate most commonly is acquired from the infected maternal mucosa during passage of the infant through the birth canal.

Immaturity of host defenses and incomplete establishment of the normal orointestinal flora are likely reasons

why C albicans often acts as a pathogen in the neonate compared to a child aged several months who is not nearly as susceptible.

Candidosis of the nipple in the nursing mother is associated with infantile OPC. Nipple candidosis almost always is bilateral, with the nipples appearing bright red and inflamed,

some patients may develop soreness and cracks at the lateral angles of the mouth (angular cheilitis).

Denture stomatitis presents as chronic mucosal erythema typically beneath the site of a denture.