BMI11 - Fungal Skin Infections

What are mycoses?

Mycoses are diseases caused by fungi.

What are the three major categories of fungal skin infections?

Superficial mycoses, cutaneous mycoses, and subcutaneous mycoses.

What distinguishes eukaryotic organisms from prokaryotic organisms?

Eukaryotic organisms possess a membrane-bound nucleus surrounded by a nuclear membrane.

What are superficial mycoses?

Superficial mycoses are fungal infections that grow only on the outermost layers of the skin or the cuticle of the hair shaft.

Where do superficial mycoses grow?

They grow only on the outermost layers of skin and the cuticle of hair shafts.

Do superficial mycoses typically induce a strong immune response?

No, superficial mycoses rarely induce an immune reaction.

How destructive are superficial mycoses?

They cause minimal tissue destruction and disease.

How are superficial mycoses usually diagnosed?

They are usually readily diagnosed because of their characteristic appearance and superficial location.

How do superficial mycoses generally respond to treatment?

They respond well to antifungal therapy and good hygiene.

What is a primary example of a superficial mycosis?

Tinea versicolor caused by Malassezia furfur.

What type of fungus is Malassezia furfur?

Malassezia furfur is a yeast.

Is Malassezia furfur part of the normal microbiota?

Yes, it is part of the normal microbiota beginning in late childhood.

What does Malassezia furfur require for growth?

It requires oily substances such as sebum for growth.

Why is Malassezia furfur commonly found on human skin?

Human skin produces sebum, which provides the oily environment required for growth.

Is Malassezia furfur usually pathogenic?

No, it is usually an innocuous member of the normal microbiota.

What superficial fungal infection can Malassezia furfur cause?

Tinea versicolor.

What are the two morphological forms of Malassezia furfur?

A yeast form (round cells) and a hyphal form (filamentous cells).

What is tinea versicolor?

A superficial fungal skin infection caused by Malassezia furfur.

Is tinea versicolor a superficial or cutaneous mycosis?

Tinea versicolor is a superficial mycosis.

What is seborrheic dermatitis?

A skin condition associated with Malassezia yeasts that causes erythema and scaling in sebaceous areas of the body.

What common scalp condition is associated with seborrheic dermatitis?

Dandruff.

Which organism has been implicated in the pathogenesis of dandruff?

Malassezia species.

What skin changes occur in seborrheic dermatitis?

Erythema (redness) and scaling.

Which body regions are commonly affected by seborrheic dermatitis?

The chest, upper back, eyebrows, alae nasi, behind the ears, and external ears.

How is seborrheic dermatitis treated?

With topical azole creams and ketoconazole-containing products.

Which antifungal medication is commonly found in dandruff shampoos?

Ketoconazole.

Is relapse common after treatment of seborrheic dermatitis?

Yes, relapse is common.

What are cutaneous mycoses?

Cutaneous mycoses are fungal infections caused by dermatophytes that invade keratinized tissues of the skin, hair, and nails.

What organisms cause cutaneous mycoses?

Dermatophytes, which are skin-invading molds.

What tissues are affected by dermatophytes?

Keratinized tissues of the epidermis, hair, and nails.

What are dermatophytes?

Dermatophytes are molds that invade and grow within keratinized tissues such as skin, hair, and nails.

Why are dermatophytes able to infect skin, hair, and nails?

Because they utilize keratin as a nutrient source.

What is another name for cutaneous mycoses?

Tineas.

What does the term "tinea" mean?

The term "tinea" means worm.

Are tineas actually caused by worms?

No, tineas are fungal infections despite the name suggesting worms.

How do cutaneous mycoses compare to superficial mycoses in invasiveness?

Cutaneous mycoses are more invasive than superficial mycoses.

Can cutaneous mycoses cause inflammation?

Yes, they often induce inflammatory reactions.

Why may adults be more resistant to dermatophyte infections than children?

The inflammatory response may contribute to increased resistance in adults.

Can dermatophyte infections become chronic?

Yes, they may cause chronic disease.

How are most dermatophyte infections treated?

Usually with topical antifungal medications.

When are systemic antifungals needed for dermatophyte infections?

For nail infections, hair infections, or widespread disease.

What is tinea corporis?

A dermatophyte infection of the body commonly called ringworm.

What is the common name for tinea corporis?

Ringworm.

What body region is affected by tinea corporis?

The skin of the trunk, arms, legs, and other non-hairy body surfaces.

What is tinea pedis?

A dermatophyte infection of the feet commonly known as athlete's foot.

What is the common name for tinea pedis?

Athlete's foot.

What factors are associated with tinea pedis?

Wearing shoes and having sweaty feet.

Why are sweaty feet a risk factor for tinea pedis?

Dermatophytes thrive in warm, moist environments.

What environmental conditions favor tinea pedis?

Warm, moist conditions such as those found inside shoes.

What is tinea cruris?

A dermatophyte infection of the groin commonly called jock itch.

What is the common name for tinea cruris?

Jock itch.

What is tinea capitis?

A dermatophyte infection of the scalp.

What body site is affected by tinea capitis?

The scalp and scalp hair.

What is tinea barbae?

A dermatophyte infection involving the beard region.

What body site is affected by tinea barbae?

The beard and facial hair region.

What is tinea unguium?

A dermatophyte infection of the nails.

What is another name for tinea unguium?

Onychomycosis.

What body structure is infected in onychomycosis?

The fingernails or toenails.

Which tinea infection is the most difficult to treat?

Tinea unguium (onychomycosis).

Why is tinea unguium difficult to treat?

The infection is located within the nail, making drug penetration difficult and requiring prolonged therapy.

What treatment may be required for severe tinea unguium?

Oral antifungals for months and sometimes nail removal.

What is ringworm of the face?

A dermatophyte infection involving the facial skin.

Can dermatophyte infections occur as occupational infections?

Yes, occupational exposure can result in dermatomycosis.

What is dermatomycosis?

Another term for a dermatophyte fungal infection of the skin, commonly called ringworm.

What are the main goals of preventing tinea infections?

Maintaining hygiene and keeping the skin dry.

Why is skin dryness important in preventing dermatophyte infections?

Dermatophytes grow best in moist environments.

What topical antifungal medications are commonly used for tinea infections?

Topical azoles and topical terbinafine.

Which oral antifungal medications are used for severe tinea infections?

Oral azoles and oral terbinafine.

Which tinea infections usually require systemic treatment?

Nail infections, hair infections, and widespread dermatophyte infections.

How long is treatment for dermatophyte infections typically required?

Several weeks to several months.

How long may treatment of toenail onychomycosis require?

Up to 24 weeks of therapy.

What is pulsed antifungal therapy?

A treatment strategy in which antifungal medication is given for one week each month.

Why might oral antifungals be preferred for nail infections?

Topical medications often do not penetrate the nail adequately.

What can happen if a fungal skin infection is treated with topical corticosteroids alone?

The infection may worsen or persist because corticosteroids do not eliminate the fungus.

What are subcutaneous mycoses?

Fungal infections involving deeper tissues beneath the skin that are usually introduced through trauma or puncture wounds.

How infectious are subcutaneous mycoses under normal conditions?

They have a low degree of infectivity.

How are subcutaneous mycoses usually acquired?

Through traumatic implantation such as puncture wounds or injuries.

Where are the organisms causing subcutaneous mycoses commonly found?

In soil and decaying vegetation.

Who is most susceptible to subcutaneous mycoses?

Individuals who experience traumatic implantation of fungi into tissues, especially through puncture wounds or contaminated injuries.

What types of injuries commonly lead to subcutaneous mycoses?

Puncture wounds, splinters, thorn injuries, and other traumatic injuries.

How are subcutaneous mycoses treated?

Treatment depends on the organism and tissue involvement and may include chemicals, antifungal drugs, surgery, or combinations of these approaches.

Why is correct diagnosis important in subcutaneous mycoses?

Several bacterial infections can mimic subcutaneous fungal infections but require different treatments.

Can bacterial infections resemble subcutaneous mycoses?

Yes, several bacterial infections can clinically mimic subcutaneous fungal infections.

What major natural disaster was associated with necrotizing fungal soft tissue infections?

The 2011 tornado in Joplin, Missouri.

How many people were injured in the Joplin tornado outbreak?

Approximately 1,000 people were injured.

How many deaths occurred from the Joplin tornado by June 10, 2011?

159 deaths.

How many necrotizing fungal soft tissue infections were initially identified after the Joplin tornado?

Eight cases were initially identified.

How many total fungal soft tissue infection cases eventually occurred after the Joplin tornado?

Thirteen cases.

What caused many of the fungal infections following the Joplin tornado?

Embedded wood fragments and splinters driven into tissue by high winds.

What wound management was performed in the emergency department after the tornado?

Wounds were cleaned and foreign debris was removed.

How many affected patients required ICU admission following the tornado-associated fungal infections?

Ten patients required intensive care admission.

How many patients died from the tornado-associated fungal infections?

Five patients died.

Which fungal species caused the necrotizing soft tissue infections after the Joplin tornado?

Apophysomyces trapeziformis.

To what fungal group does Apophysomyces trapeziformis belong?

Mucormycetes (formerly called Zygomycetes).

Do Apophysomyces species usually cause disease in healthy individuals?

No, they usually cause opportunistic infections.

How did Apophysomyces trapeziformis cause severe disease in immunocompetent individuals after the tornado?

Traumatic implantation directly into tissues allowed the fungus to establish invasive infection.

Can subcutaneous fungal infections occur in immunocompetent individuals?

Yes, traumatic implantation can lead to severe infections even in immunocompetent hosts.

How are necrotizing fungal soft tissue infections treated?

With systemic antifungal medications and, when necessary, surgical intervention.