Fungal Infections of The Skin

Skin fungal infections are clinically divided into:

Superficial

Tinea versicolor, Piedra (Trichosporosis), and Tinea nigra.

Cutaneous

Dermatophytosis, Candidiasis of skin and mucosa, nails and others.

Subcutaneous

Mycetoma, Sporotrichosis, Chromoblastomycosis, and others.

Superficial Mycoseso Infections in which a pathogen is restricted to the

stratum corneum, with little or no tissue reaction.

o Affect the upper dead layers of skin or hair shaft.

o Painless and usually do not provoke immune response.

o They include:

Tinea versicolor Tinea nigra Piedra

Tinea Versicolor o Tinea versicolor is a chronic fungal infection of the

skin. More common in teens and young adults.

o The fungus interferes with the normal pigmentation of the skin resulting in small, discolored patches (white, pink, tan or dark brown, slow-growing, scaly and mildly itchy)

o Common sites: the back, upper arms, chest, and neck.

o Sun exposure make tinea versicolor more apparent.

o Tinea versicolor often recurs, especially in warm, humid weather.

o Causative agent: Malassezia furfur, and Malassezia globosa. Lipophilic yeasts.

o Both are normal flora of skin cause disease when overgrow. (not contagious)

o Triggering factors: Hot, humid weather, excessive sweating, oily skin, hormonal changes and weakened immune system.

o Diagnosis:

Skin scraping: potassium hydroxide (KOH). which dissolves keratin and make it easier to see the fungi.

Culture: add oil to the media Sabouraud dextrose agar (SDA).

Pityriasis versicolor commonly causes hypopigmentation in people with dark skin.

Microscopy: Tinea versicolor Positive for short hyphae and yeast cells:

Spaghetti and meatballs.

Tinea nigrao Dark brown to black painless patches on the

palms of the hands and the soles of the feet.

o Causative fungi: Hortaea werneckii (acquired from soil or wood)

o Diagnosis:

o Skin scrapings: in 10% or 20% KOH, brown septate hyphae.

o Culture on Sabouraud dextrose agar (SDA) & Mycobiotic agar, growth of dematiaceous fungus (produce melanin in their cell walls).

Agar plate with the black yeast Hortaea werneckii

Skin scrapings in 10% KOH: dark olivaceous (dematiaceous) hyphal elements and 2-celled yeast cells of Hortaea werneckii

Piedra (Spanish; stone or rock)o Asymptomatic infection of the hair shaft, causing

nodules on the hair shaft (scalp hair, mustache, and beard) leading to weakness and break of the hair.

o Black piedra: Piedraia hortae. Dark nodules hard and firmly attached to hair shaft.

o White piedra: Trichosporon beigelii. Lightly pigmented, white to brown nodules soft, loosely attached.

o Diagnosis: Direct Microscopy: test the hair using 10% KOH. Culture on Sabouraud's dextrose agar (SDA).

white piedraHair with black Piedra

Treatment of Superficial infections

o 2% salicylic acid or 3% sulfur ointments or Whitfield's ointment.

o Anti fungal: Ketoconazole topically or systemically.

o Piedra: clipping or shaving the hair or apply 2% salicylic acid or 3% sulfur ointment or nizoral shampoo (contains Ketoconazole)

Cutaneous fungal infection:- Dermatophytosis.

- Candidiasis.

Dermatophytosis• Fungal infections of the Keratinized tissues of

the body : scalp, glabrous skin, and nails

• caused group of fungi known as dermatophytes which are primary pathogens.

Transmission:

• Geophilic species: soil saprophytes.

• Zoophilic species: animals (goats, sheep, camel, cows, horses) .

• Anthropophilic species: humans.

• From one body area to another.

Dermatophytes Etiology (filamentous mold like fungi):

• Microsporum: infections on skin and hair.

• Epidermophyton: infections on skin and nails.

• Trichophyton: skin, hair, and nails.

• Clinically: Tinea or ringworm

T. capitis scalp T. corporis skin T. pedis foot (Athlete’s foot) T. cruris groin

Diagnosis: KOH and culture on SDA. (skin scraping, hair, or nail).

Microsporum canis Epidermophyton floccosum

Trichophyton mentagrophytes

Tinea Capitis

Ringworm of the scalp and hair shafts.

Most common in toddlers and school-age children.

Highly contagious infection: by direct contact or by sharing objects like combs or from animals.

Slow growing, scaly, gray or red round patches (ring). The hair is fragile and break off at or just above the scalp (black dots).

Severe inflammation may cause scarring or permanent hair loss.

Diagnosis: Woods lamp, KOH & culture.

Treatment: oral or topical (shampoo). Griseofulvin or terbinafine for 6 weeks or more.

Tinea capitis

Complications: Kerion result from host's response to the fungal infection of the hair follicles of the scalp and beard accompanied by secondary bacterial infection(s)

Tinea Corporis (body ringworm)

Itchy, red circular or irregular rash with healthy-looking skin in the middle (ring). It can be flat or slightly raised. Mainly on the trunk or the face.

Transmission: from human, animal, objects or soil.

Predisposing factors: humid or crowded conditions, excessive sweating, sports such as wrestling or football, wearing tight clothing.

Immunocompromised: widely disseminated and may invade the dermis. Difficult treatment

Diagnosis: ?????

Treatment: Topical or oral (Griseofulvin, azoles or terbinafine)

Ringworm in healthy & immunocompromised Tinea unguium & Tinea pedis

Candidiasis (Yeast Infection)

• Candida is a yeast that is a normal flora. Candida albicans is the most common spp.

• Candidiasis: Over growth of candida on skin (particularly warm & moist areas), genitalia, throat, mouth or blood.

• Oral candidiasis (thrush), diaper rash, yeast infection of genital area (vulvovaginal candidiasis), invasive candidiasis, candidemia.

• Symptoms and treatment depend on which part of the body is infected.

Oral Candidiasis (Thrush):

• Candidal infection of the mouth or throat.

• White batches in the mouth and tongue with redness, cracking at corners of the mouth, sore throat and difficult swallowing.

• Most often seen in: Infants, elderly, antibiotics treatment, immunocompromised (e.g. AIDS, steroid treatment, diabetes, chemotherapy patients……..).

• Treatment depends on: immune status, age and severity of the infection. Antifungals: mouthwash, dissolvable pills.

Angular cheilitis: mouth corners

Yeast Infection of the Genitals• Vaginal candidiasis: Common symptoms:

o Extreme itching in the genital area.

o Soreness and redness in the genital area.

o White, clumpy vaginal discharge.

o Painful intercourse.

• Symptoms in men include (candidal balanitis): red rash on genitalia and penis with itching or burning.

• Sexual partner should be treated as well.

• Diaper Rash

o Some diaper rashes can be caused by candida.

o Symptoms: Dark red patches on the diaper area, especially in the folds near the thighs or yellow, fluid-filled spots that open and become flaky.

o Treatment: topical antifungal (cream, ointment, or powder).

• Invasive candidiasis & candidemia: risk factors: weak immunity, hospitalization esp. in ICU, recent surgery, central line (catheter), low birth weight.

o Vague symptoms, no response to antibiotics, treat with IV antifungal.

Subcutaneous Fungal Infection:- Mycetoma: endemic in different parts of KSA.- Chromoblastomycosis.

Chromoblastomycosis Madura Foot (Mycetoma)