Term
| Name 4 groups of parasites that can infect the superficial structures of the hair, nails, and stratum corneum of the skin. |
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Definition
| Pityriasis versicolor, Tinea nigra, black piedra, white piedra |
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Term
| What disease is caused by Malassezia furfur? |
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Definition
| Pityriasis (tinea) versicolor |
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Term
| What kind of disease is pityriasis (tinea) versicolor? |
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Definition
| Chronic, superficial fungal disease of the skin. |
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Term
| Describe pityriasis (tinea) versicolor. |
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Definition
| The lesions are hypopigmented or hyperpigmented macules. The most common sites include the back, axillary, upper arm, chest, and neck. The lesions scale easily, giving them a chalky appearance. There is no surrounding erythema, the lesions are not elevated, causing only mild itching. Otherwise, no discomfort. Does not elicit an immune response. |
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Term
| What is the normal habitation of the organism that causes tinea versicolor? |
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Definition
| Around the openings of hair follicles. Not found in animals. Most commonly found in adolescents and young adults. |
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Term
| How is tinea versicolor transmitted? Who is normally affected? |
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Definition
| Person-to-person spread, direct or indirect. Young adults and adolescents are most often affected; up to 60% of populations in tropical regions. |
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Term
| How is tinea versicolor diagnosed? |
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Definition
| Direct microscopy: epidermal scales with 10% KOH. "Spaghetti and meatballs" appearance. Large round yeasts with angular hyphae. Wood lamp: fluoresce yellow-green. Not necessary to culture. |
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Term
| How is tinea versicolor treated? |
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Definition
| Azoles. Smaller infected areas can be treated with selenium sulfide in a shampoo. |
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Term
| Where is tinea nigra most frequently found on the body? |
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Definition
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Term
| What type of infection is tinea nigra? |
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Definition
| Superficial infection located on the palms. |
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Term
| Name and describe the disease that Hortaea werneckii causes? |
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Definition
| Tinea nigra; the lesions are dark-colored, non-scaling, and asymptomatic (no inflammatory reaction). The yeast is a black yeast that produces melanin (dermatiaceous). |
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Term
| Tinea nigra is normally found in what regions? |
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Definition
| Tropical or semitropical areas of Central and South America, Africa, Asia. |
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Term
| How is tinea nigra diagnosed? |
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Definition
| Skin scrapings prepared with 10% KOH. Can culture on Sabouraud's media; appears as pale, moist yeast colonies which darkens with age (due to the growth of hyphae). |
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Term
| How is tinea nigra treated? |
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Definition
| Topical antifungals such as azoles and Whitefield's ointment. |
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Term
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Definition
| Asymptomatic fungal infection of the hair shaft. The nodules are dark in color, hard, and firmly attached to the hair shaft. Usually affects scalp hair; eventually the fungus may weaken the hair shaft to the extent that it breaks. |
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Term
| Black piedra is normally found in what regions? |
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Definition
| Tropical regions such as Central and South America and Africa. |
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Term
| How is black piedra diagnosed? |
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Definition
| Dermatiaceous hyphae and ascospores. Culture on Sabouraud's medium and incubate at room temp (25 degrees) for 4-6 weeks. |
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Term
| How is black piedra treated? |
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Definition
| Haircut and regular washings. |
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Term
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Definition
| Asymptomatic fungal infection of the hair shafts. Light-colored, soft nodules that are loosely attached to hairs and my cause the hair shafts to break. Mostly found on the hair on the groin and axillae. |
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Term
| The genus Trichosporon causes what disease? |
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Definition
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Term
| White piedro is most common in what regions? |
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Definition
| Tropical and subtropical zones (associated with poor hygiene). |
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Term
| How is white piedra diagnosed? |
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Definition
| The nodules are not as discrete and not as dark as those found in black piedra. Microscopically, septate hyphae can be seen that develop into arthroconidia. Culture on Sabouraud's agar without cyclohexamide for 2-4 weeks at room temperature.The colonies appear rough, membranous, white to light or tan colonies. |
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Term
| How is white piedra treated? |
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Definition
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Term
| How do dermatophytes grow on skin and other superficial structures? |
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Definition
| They possess keratinase, an enzyme which allows them to utilize keratin as a nutrient and energy source. |
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Term
| What is the infection of keratinized structures? |
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Definition
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Term
| What are the three genera of fungi that cause tinea? |
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Definition
| Trichophyton, Epidermophyton, Microsporum |
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Term
| Is there an inflammatory response to the organisms that cause ringworm? |
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Definition
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Term
| What are the three categories of organisms causing ringworm/tinea? |
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Definition
| Geophilic: normally live in soil, occassional pathogens of animals and humans. Zoophilic: primarily parasitize the body surfaces of animals but can be transmitted to humans. Arthropophilic: generally infect humans and are transmitted between individuals via close human contact, sharing items (clothes, combs, brushes, towels, bed sheets), and crowded living conditions. |
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Term
| Name and describe the disease caused by Trichophyton rubrum and Trychophyton mentagrophytes. |
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Definition
| Tinea pedis (athletes foot)- scaling, maceration, and itching between the toes. |
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Term
| How is tinea pedis transmitted? |
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Definition
| Transmitted via the feet by desquamated skin scales in substrates like carpet. |
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Term
| Name and describe the disease caused by trichophyton rubrum and Epidermophyton floccosum. |
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Definition
| Tinea cruris- jock itch; infection of teh groin seen mainly in men. Lesions are sharply defined with erythematous borders with a normal appearance in the middle. |
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Term
| What is the disease most commonly caused by Microsporum canis? |
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Definition
| Tinea capitus (scalp ringworm) |
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Term
| What are the diseases that are commonly caused by trichophyton rubrum? |
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Definition
| Tinea pedis, tinea cruris, tinea corporis, and tinea unguium. |
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Term
| What disease is also called dermatophyte onychomycosis? |
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Definition
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Term
| How are cutaneous mycoses diagnosed? |
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Definition
| Scrapings from clinical specimens. 10% KOH and calcofluor white; will see filamentous hyphae. Some fluoresce with Wood's lamp. Can culture on Sabouraud's media and grow 1-3 weeks. |
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Term
| What is the treatment for cutaneous mycoses infection? |
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Definition
| Topical azoles or oral terbinafine. |
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Term
| What are subcutaneous mycoses? |
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Definition
| Chronic, localized infections of the epidermis and adjacent connective tissue and lymphatics following traumatic implantation of the organism. |
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Term
| Are subcutaneous mycoses transmissible? |
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Definition
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Term
| Causative fungi of this type of infection are all soil saprophytes. |
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Definition
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Term
| What disease is usually caused by Fonsecaea, Phialophora, Cladosporium, and Rhinocladiella? |
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Definition
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Term
| What occurs in chromoblastomycosis? |
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Definition
| First, small elevated itchy patches appear. New patches appear over subsequent months, becoming reddish purple and hard. Next, rough, warty, cutaneous nodules appear (raised 1-3 cm above skin surface; resemble the florets of cauliflower). These nodules may block lymphatic system and cause elephantiasis. Sometimes a bacterial infection can cooccur and cause systemic illness. |
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Term
| How is chromoblastomycosis diagnosed? |
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Definition
| Scrapings from surface lesions with 20% KOH. Sclerotic bodies usually easily seen. Dematiaceous thick walled yeast cells are seen. Non-budding but multiplane septation. Can be cultured on Sabouraud's agar for 4-6 weeks at 37 degrees; colonies appear dark and velvety. |
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Term
| How is chromoblastomycosis treated? |
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Definition
| Terbinafine or azole; heat to shrink lesions. Antifungals not always effective. |
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Term
| Chromoblastomcosis normally occurs in what regions? |
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Definition
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Term
| Name and describe the disease caused by Sporothrix schenckii. |
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Definition
| Lymphocutaneous sporotrichosis- caused by dimorphic fungus. Chronic infection involving cutaneous, subcutaneous, and lymphatic tissue. Primary fixed cutaneous lesion at site of injury are small papules most often occurring on an extremity. Lymph nodes become sequentially infected as organisms are swept along the lymph channels. Nodes become enlarged, firm, and discolored. Dissemination is limited to immunocompromised patients. |
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Term
| What disease is also called Rose Gardener's disease? |
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Definition
| Lymphocutaneous sporotrichosis; known to grow on roses, woody plants, and rich organic soil. Most cases are traced back to plant materials penetrating the skin. |
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Term
| Lymphocutaneous sporotrichosis is normally found where? |
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Definition
| Tropical and subtropical (although may be found worldwide). Most common in Mexico; endemic in Brazil, Uruguay, and South Africa. |
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Term
| How is lymphocutaneous sporotrichosis diagnosed? |
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Definition
| Direct microscopy: sparse yeast cells, asteroid body also seen with other infections. Culture of pus or tissue: 2-5 days. Subculture mold, growth as yeast at 37 degrees. Exoantigen test. |
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Term
| How is lymphocutaneous sporotrichosis treated? |
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Definition
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Term
| Name and describe the disease caused by Madurella, Exophiala, Phaeoacremonium, Fusarium. |
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Definition
| Eumycotic mycetoma- progressive, tumor-like disease of the hand or foot due to chronic fungal infection; may lead to loss of a body part. Appears in tissue as grainy and characteristic pus production. Lesions progress from subcutaneous swelling to infecting and destroying deeper tissue, muscle, fascia, and bones. Remains localized to limb. Traumatic implantation- noncontagious. The subq swelling is hard and swelling; ruptures near surface and infects deeper tissues. |
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Term
| How is eumycotic mycetoma diagnosed? |
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Definition
| Recover granules- black, red, or white. Microscopy with 20% KOH. 2-6 micrometers are fungal, less than .5 micrometers are actinomycetes. Culture with penicillin. |
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Term
| How is eumycotic mycetoma treated? |
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Definition
| Terbinafine and amputation |
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Term
| Name and describe the disease caused by Exophiala, Wangiella, Bipolaris, Curvularia, and Alternaria. |
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Definition
| Subcutaneous Phaeohyphomycosis- subcutaneous cysts on feet, legs, and other body sites; usually painless. Can also cause brain and nasal sinus infections. Found in soil and plant debris->traumatic entry. |
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Term
| How is eumycotic mycetoma diagnosed? |
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Definition
| Excision of cysts: fibrous cysts and central necrosis. Pigmented fungal elements. The tissue morphology of the causative organism is mycelial. |
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Term
| How is eumycotic mycetoma treated? |
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Definition
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Term
| Name and describe the disease caused by Basidiobolus ranarum. |
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Definition
| Basidiobolomycosis- normally found in children. Traumatic implantation, moveable masses on various parts of the body. Lesions may ulcerate. |
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Term
| What two diseases are considered to be subcutaneous zygomycosis? |
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Definition
| Basidiobolomycosis and Conidiobolomycosis |
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Term
| Name and describe the disease caused by Conidiobolus coranatus. |
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Definition
| Conidiobolomycosis- found in young adults most often; swelling of the face, firm and painless. Caused b/c of inhalation. |
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Term
| Subcutaneous zygomycosis is diagnosed how? |
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Definition
| Clinical features and biopsy (hyphae surrounded by eosinophils). |
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Term
| How is subcutaneous zygomycosis treated? |
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Definition
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Term
| Give three examples of systemic mycoses. |
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Definition
| Histoplasmosis, coccidioidomycosis, and blastomycosis. |
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Term
| What is the route of acquisition of systemic mycoses? |
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Definition
| Inhalation of spores of dimorphic fungi that have their mold forms in the soil. |
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Term
| What occurs when systemic mycoses spores are inhaled into the lungs? |
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Definition
| The spores differentiate into yeasts. |
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Term
| Do persons infected with systemic mycoses communicate the diseases to other? |
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Definition
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Term
| Where is histoplasmosis commonly found? |
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Definition
| Distribution is worldwide, but it is most prevalent in eastern and central regions of the US (Ohio, Mississippi, Kentucky). AKA Ohio Valley Fever |
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Term
| What kind of environment is Histoplasma capulatum most commonly found? |
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Definition
| Moist soil high in nitrogen content (bat and avian habitats). |
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Term
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Definition
| Inhaled conidia convert to budding yeast cells. They are phagocytized by alveolar macrophages; they then produce alkaline substances that raise the pH and inactivate the degradative enzymes of the phagolysosome. Acute pulmonary histoplasmosis: flu-like symptoms, fever, chills, headache, patchy pulmonary infiltrates. Disseminated histoplasmosis develops in a minority of infected persons (anorexia, fatigue, oral ulcers, hepatosplenomegaly). |
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Term
| How is histoplasmosis diagnosed? |
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Definition
| Direct examination->yeast cells within macrophages. During culture, the mold turns to yeast. Exoantigen test, nucleic acid test, patient antibodies, antigen in urine or serum. |
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Term
| What is the treatment for histoplasmosis? |
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Definition
| Usually self-limiting infection. Azole or amphotericin B. |
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Term
| Where is coccidioidomycosis usually found? |
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Definition
| Found in alkaline soils in semiarid, hot climates; endemic to SW US and Latin America. |
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Term
| Describe the morphology of the organism that causes coccidioidomycosis. |
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Definition
| Distinctive morphology; blocklike arthroconidia in the free-living stage and spherules containing endospores in the lungs. *arthrospores are very light and are carried by the wind and inhaled from dust. |
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Term
| Describe coccidioidomycosis. |
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Definition
| Frequently asymptomatic, primarily pulmonary disease with flu-like symptoms, fever, cough, chest pain. Usually self-limiting. May be accompanied by a erythematous macular rash. Progressive pulmonary disease. May become a disseminated disease to almost any organ (meninges, bone, skin). It is a defect in cell-mediated immunity. |
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Term
| How is coccidioidomycosis diagnosed? |
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Definition
| Direct examination of spherules in sputum: sputum (use 10-20% KOH with calcofluor white) or tissue (use H&E). Culture not necessarily done b/c highly infectious. Patient antibodies. |
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Term
| What is the treatment for coccidioidomycosis? |
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Definition
| Not needed in many cases. Amphotericin B or azoles. |
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Term
| Where is blastomycosis normally found? |
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Definition
| Free-living species distributed in soil of a large section of the Midwestern and Southeastern US. |
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Term
| How is blastomycosis contracted? |
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Definition
| Inhaled conidia convert to yeast and multiply in lungs. |
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Term
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Definition
| Primary pulmonary disease; frequently asymptomatic and self-limiting. Flu-like symptoms, fever, cough, chest pain. Disseminated disease to skin, bone, CNS, spleen. Chronic cutaneous disease: dissemination from lungs. Single or multiple ulcerating lesions of face, neck, scalp, and hands. |
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Term
| How is blastomycosis diagnosed? |
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Definition
| Direct examination of budding yeast; culture: mold growth at 25-30 degrees. Converts to yeast at 37 degrees. Exoantigen test, nucleic acid test. |
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Term
| What is the treatment for blastomycosis? |
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Definition
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Term
| What are three examples of opportunistic fungal infections? |
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Definition
| Candidiasis, cryptococcosis, and aspergillosis. |
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Term
| Where is candida albicans normally found? |
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Definition
| Widespread yeast; normal flora of oral cavity, genitalia, large intestine, and skin of humans. Causes primarily endogenous infections. |
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Term
| Describe infections that can be caused by candida albicans. |
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Definition
| Can be short-lived superficial skin irritations to overwhelming, fatal systemic diseases. Thrush- thick, white, adherent growth on the mucus membrane of mouth and throat. Vulvovaginal yeast infection- inflammatory condition of the female genital region that causes itching and a white discharge. Cutaneous candidiasis- occurs in chronically moist areas of the skin (diaper rash). Chronic mucocutaneous candidiasis (CMC)- defect in T-cell mediated immune response (lesions fail to heal). GI infection, UTI, hematogenous infection (eyes, bones, joints, brain, CNS, endocarditis). |
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Term
| How is candidiasis diagnosed? |
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Definition
| Direct examination: budding yeast cells and budding pseudohyphae. Growth on CHROMagar; differentiates Candida species. |
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Term
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Definition
| Topical azoles for superficial infections; amphotericin B or azoles for systemics. |
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Term
| Where are organisms found that cause cryptococcosis? |
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Definition
| Widespread, found in soil, especially with bird droppings. |
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Term
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Definition
| Frequently asymptomatic, pulmonary symptoms include cough, fever, and lung nodules. Dissemination causes lesions on skin, eyes, and bone. Most common disease is meningitis. Slow onset with nonspecific symptoms (headache, irritability, dizziness) appear over a few weeks or months. May also see behavioral changes, fever, seizures, dementia and decreased levels of consciousness. Can be fatal if not treated. |
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Term
| How is cryptococcosis diagnosed? |
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Definition
| Direct microscopy via india ink stain/gram stain. Appear as mucoid colonies after 3-5 days of culture. Biochemical tests: phenol oxidase and urease. Capsule antigen in serum or CSF (rapid, sensitive, specific). |
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Term
| What is the treatment for systemic cryptococcosis? |
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Definition
| Amphotericin B and fluconazole for 2 weeks, with azole for 8 weeks. |
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Term
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Definition
| Allergic aspergillosis: asthma, cough, fever, nasal obstruction, headache, discharge, facial pain, pulmonary infiltrates. Pulmonary aspergillosis- underlying pulmonary disease. Aspergilloma- fungus ball. Usually no tissue damage, so no treatment is needed. If hemorrhage occurs, surgery is needed. Invasive pulmonary aspergillosis- only in immunocompromised patients or underlying pulmonary disease. Invasion into tissue by hyphae. Fever, pulmonary infiltrates, chest pain, coughing up blood. Disseminated aspergillosis- infection of brain, heart, liver, spleen. |
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Term
| How is aspergillosis diagnosed? |
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Definition
| Direct examination, large branching septate hyphae. Culture on mycolic media without cyclohexamide Detection of antigen in serum. Treatment includes amphotericin B or azole. |
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