Selling a Product or ServiceFUNGAL SKIN INFECTIONS

I

IHAB YOUNIS, M.D.

• At one time it was thought that fungi were plants that did not need photosynthesis

• But now fungi are classified in their own kingdom, separate from plants and animals because:

1- The cell walls of plants are made of cellulose whereas the walls of fungal cells are made of chitin

2- Plants require only simple inorganic compounds such as carbon dioxide and water to grow. Fungi require a diet of complex organic molecules to thrive

• Fungi may be broadly divided into two basic forms, moulds and yeasts

– Moulds are made up of long multinucleate filaments called hyphae– Yeasts are unicellular, made up of

ovoid to globose cells which usually reproduce by budding

• Dermatophytes are fungi that can cause infections of the skin, hair, and nails

• They colonize the keratin and inflammation is caused by host response to metabolic by-products

• The organisms are transmitted by either direct contact with infected host (human or animal) or by direct or indirect contact with infected exfoliated skin or hair in combs, hair brushes, clothing, furniture, theatre seats, caps, bed linens, towels, hotel rugs, and locker room floors

• Depending on the species, the organism may be viable in the environment for up to 15 months

Classification of dermophytes according to habitat• Anthropophilic dermatophytes are

restricted to human hosts and produce a mild, chronic inflammation

• Zoophilic organisms are found primarily in animals and cause marked inflammatory reactions in humans who have contact with infected cats, dogs, cattle, horses, birds, or other animals.

• Geophilic species are usually recovered from the soil but occasionally infect humans and animals. They cause a marked inflammatory reaction, which limits the spread of the infection and may lead to a spontaneous cure but may also leave scars

The main 3 genera of dermatophytes are:

• Trichophyton

• Epidermophyton

• Microsporum

Classification of fungal skin diseases

A. Superficial mycoses

Infections limited to the outermost layers of the skin and hair:– Pityriasis versicolor– Candidiasis – Tinea nigra – Black piedra– White piedra 

B. Cutaneous mycoses

• Infections that extend deeper into the epidermis, as well as hair and nail and caused by dermatophytes:– Tinea capitis – Tinea corporis  – Tinea manus – Tinea cruris – Tinea pedis – Tinea unguium

C. Subcutaneous mycoses

Infections involving the dermis, subcutaneous tissues, muscle & fascia: – Sporotrichosis –  Chromoblastomycosis –  Mycetoma 

D. Systemic mycoses

• Infections that originate primarily in the lung and may spread to many organs

Tinea Versicolor

Etiology

• Malassezia furfur (Syn. Pityrosporon orbiculare, Pityrosporon ovale, and Malassezia ovalis)

• A member of normal human cutaneous flora, and it is found in 18% of infants and 90-100% of adults

• The condition is more noticeable during the summer months

• 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 to the parasitic, mycelial morphologic form include a genetic predisposition; warm, humid environments; immuno-suppression; malnutrition; and Cushing disease

• Prevalences reported to be as high as 50% in the humid, hot environment and as low as 1.1% in the colder temperatures

• The condition is not considered to be contagious because the causative fungal pathogen is a normal inhabitant of the skin

• Its occurrence before puberty or after age 65 years is uncommon

• The reason why this organism causes tinea versicolor in some individuals while remains as normal flora in others is not entirely known

• Several factors, such as the organism's nutritional requirements and the host's immune response to the organism, are significant

• Evidence has been accumulating to suggest that amino acids (rather than lipids as previously thought) are critical for the appearance of the diseased state

• In vitro, the amino acid asparagine stimulates the growth of the organism, while glycine induces hyphal formation

• In vivo, the amino acid levels have been shown to be increased in the uninvolved skin of patients with tinea versicolor

• Lymphocyte function on stimulation with the organism has been shown to be impaired in patients who are affected

Clinically

• Numerous, well-marginated, finely scaly, oval-to-round macules

• Scattered over the trunk and/or the chest, with occasional extension to the lower part of

the abdomen, the neck, and the proximal extremities

• The macules tend to coalesce, forming irregularly shaped patches

• As the name versicolor implies, the color of each lesion varies from almost white to reddish brown or fawn colored

• An inverse form also exists affecting the flexural regions, the face, or isolated areas of the extremities

• This form is more often seen in hosts who are immunocompromised

Cutaneous Candidiasis

Etymology : Latin, feminine of candidus=Clear

Etiology

• Candida albicans yeasts are unicellular fungi that typically reproduce by budding, a process that entails pinching off of the mother cell

• It has the ability to exist in both hyphal and yeast forms (dimorphism)

• If pinched cells do not separate, a chain of cells is produced and is termed pseudohyphae

• Candidal species are part of the normal commensal flora throughout the gastrointestinal tract (mouth through anus)

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

• Removal of bacteria from the skin, vagina and gastrointestinal tract results in reduced environmental and nutritional competition that favors the growth of candidal organisms

Incidence increased due to:

• Postnatal acquisition has been attributed to increased survival rates of low birth weight babies in association with an increased number of invasive procedures

• Older adults are more likely to be exposed to situations that increase the risk of invasive candidiasis, including treatment with broad-spectrum antibiotics , poor self-care, and decreased salivary flow

• The use of broad spectrum antibiotics, and treatment with cytotoxic agents (eg, methotrexate, cyclophosphamide) for dermatologic and rheumatic conditions or aggressive chemotherapy for malignancy

Clinical Types

Candidal vulvovaginitis

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

• Although most candidal infections occur

more frequently with advancing age, vulvovaginitis is unusual in older women. In the absence of estrogen stimulation, the vaginal mucosa becomes thin and atrophic, producing less glycogen. Candidal colonization of vaginal mucosa is estrogen dependent and subsequently decreases sharply after menopause

• Erythema of vaginal mucosa and vulval skin

• Curdy white flecks within the discharge• Erythema may spread to include the perineum&groin with satellite pustules• Alternatively, the vaginal mucosa may appear red and glazed

Candidal balanitis

• Signs and symptoms of this candidal infection vary but may include tiny papules, pustules, vesicles, or persistent ulcerations on the glans penis

• Exacerbations following

intercourse are common

Oropharyngeal candidiasis (oral thrush) • Acquired from the infected maternal mucosa during passage of the infant through the birth canal• Lesions become visible as pearly white patches • Buccal epithelium, gums, and the palate are

involved with extension to the tongue, pharynx,or esophagus in more severe cases

• If the lesions are scraped away, an erythematous base is exposed. Lesions may progress to symptomatic erosion and ulceration

Oral candidiasis in adults

• In older adults, the development of oral thrush in the absence of a known etiology should raise the clinician's index of suspicion for an underlying cause of immunosuppression, such as malignancy or AIDS

• With denture stomatitis, the areas of erythema may be painful and may affect up to 65% of patients who wear dentures

• Occurs as white plaques that are present on the buccal, palatal, or oropharyngeal mucosa overlying

areas of mucosal erythema

•Typically, the lesions are easily removed & may show areas with tiny ulcers

• In addition, 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

Candidal diaper dermatitis

• 85-90% of infants with OPC harbor C albicans in the intestine and feces and in most patients, CCD is the result of progressive colonization from oral and gastrointestinal candidiasis

Factors predisposing to infection:

-Infected stools-Macerated moist skin -Local irritation of the skin by friction-Ammonia from bacterial breakdown

of urea-Intestinal enzymes-Detergents and disinfectants

• Maceration of the anal mucosa and the perianal skin often is the first clinical manifestation

• Usually it starts in the perianal area, spreading to involve the perineum and, in severe

cases, the upper thighs, lower abdomen, and lower back

• The typical eruption begins with scaly papules that merge to form well-defined, weeping, eroded lesions with a scalloped border• A collar of overhanging scales and an erythematous base may be demonstrated• Satellite flaccid vesico- pustules around the primary intertriginous plaque also are characteristic

Intertrigo

• Most cases occur in skin folds where occlusion (by clothing or shoes) produces abnormally moist conditions

• Other sites include the perineum, mouth, and anus, in which Candida organisms normally may be carried

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

• Erythema, cracking, and maceration with soreness and pruritic symptoms

• Lesions typically have an irregular margin with surrounding satellite papules and pustules

• Web spaces of affected fingers or toes are macerated and have the appearance of soft white skin, which is a condition termed erosio interdigitalis blastomycetica

Paronychia

• Candida species (not always C albicans) can be isolated from most patients

• Bacteria also may act as copathogens• Immediate contact dermatitis to food

allergens may play a role • Disease is more common in people

who frequently submerge their hands in water and in diabetics

• The nailfold becomes erythematous, swollen, and tender, with an occasional discharge

• Loss of the cuticle occurs, along with nail dystrophy and onycholysis with discoloration around the lateral nailfold

• A greenish color with hypo- nychial fluid accumulation may occur that results entirely from Candida, and not Pseudomonas infection

Chronic Mucocutaneous Candidiasis

• CMC is associated with a defect in cell-mediated immunity

• The alterations include decreased IL 2 and interferon-gamma levels & increased IL 10

• Usually manifests in infancy or early childhood (60-80% of cases)

Clinically

• Infants often present with recalcitrant thrush, candidal diaper dermatitis, or both

• More extensive scaling of skin lesions and thickened nails and red, swollen periungual tissues can follow these infections

• Oral involvement may extend to the esophagus, but further extension is extremely uncommon

• Nails may be markedly thickened, fragmented, and discolored, with significant edema and erythema of the surrounding periungual tissue, simulating clubbing

• Skin lesions more frequently are acral and characterized by erythematous, hyperkeratotic, serpiginous plaques

• The scalp may be involved with similar hyperkeratotic plaques,

which can result in scarring alopecia

Tinea Nigra

Etiology

• It is due to infection by the fungus, P werneckii

• Occurs as a result of inoculation from a contamination source such as soil, sewage, wood, or compost subsequent to trauma in the affected area

Note the 2 celled yeast forms

• Tends to occur in areas with an increased concentration of eccrine sweat glands

• Hyperhidrosis appears to be a risk factor for this disease

• Typically, the incubation period is 2-7 weeks

• A pigmentary change in the skin results from the accumulation of a melanin-like substance in the fungus

Clinically• Asymptomatic brown-to-black macule

ranging from light brown to black discoloration, resembling silver nitrate or India ink stains

• The borders are typically discrete• The surface may appear mottled or velvety• The lesions are typically solitary, although may be multiple• Located on the palms and soles

• The shape of the lesion varies, and they may appear ovoid, round, or irregular

• The lesion slowly grows over weeks to months

• The size may range from a few millimeters to several centi- meters in diameter, depending on the duration

PiedraEtymology: Sp.Stone

Etiology

• White piedra is caused by the genus Trichosporon Behrend which consists of 6 human pathogenic species

• Black piedra is caused by the fungus Piedraia hortae

• Present in the soil, air, water, vegetables, or sputum

Clinically

• Black piedra– Consists of darkly pigmented, firmly

attached nodules that vary in size to as large as a few

millimeters in diameter– The nodules feel hard

– The most commonly affected area of the body is the scalp hair. Black piedra less frequently affects beards, mustaches, and the pubic hair

– The fungus grows into the hair shaft; ultimately, it may cause hair breakage because of structural instability

White piedra

– Consists of lightly pigmented, loosely attached nodules or gelatinous sheaths that have a soft texture

– The most commonly affected areas of the body are

beards, pubic & axillary hair, mustaches and eyelashes and eyebrows

– Hair breakage occurs in both forms

– In both varieties of piedra, the

surrounding skin is healthy