Mycology Flashcards
What is a Blastoconidia?
Budding yeast cell
Asexual spores produced with a spherule are called…
Endospores
Endemic mycoses are dimorphic and spread by inhalation of spores. What form of fungi is transmissible? Is person-to-person transmission possible?
Mold is the infectious form and found in soil. Yeast is present in tissues during infection, but is non-infectious so person-to-person spread is not possible.
Hyphae with cross walls are said to be…
Septated
What disease is caused by Madurella mycetomatis or Pseudallescheria boydii? How does the disease present?
Mycetoma - starts as a small, firm, painless nodule. Spreads to fascia and bone causing subcutaneous abscesses
Conidia and sporangiospores are asexual fungal spores. What is the difference between the two?
Conidia extend openly from conidiophores. Sporangiospores extend from a sporangium and are enclosed in a sac-like structure.
Describe the life cycle of Pneumocystis.
Intracystics bodies within cysts rupture and release trophs. Trophs divide by fission or fuse (sexual reproduction) to form new cysts.
These terms describe structures that contain 1 or more conidia.
Microconidia (small) & macroconidia (large)
A fungus is cultured and grown at room temperature. What form of fungi will predominate? What will happen if the temperature of the culture is raised to 37oC?
At room temperature, the mold form of growth predominates. At 37oC, the yeast form of mold predominates and fungi will resemble bacterial colonies.
What types of infections may be caused by Aspergillus spp.?
Allergic reactions, colonization of body cavities, infections of wounds and catheters, invasion of respiratory system
What is the clinical appearance of Pneumocystis pneumonia?
Fever, dyspnea, dry and nonproductive cough, hypoxemia, foamy and eosinophilic exudate. AIDS-defining illness
Another term for fungal spores is…
Conidia
This form of fungi is filamentous
Mold
What is white piedra? What fungus is the cause of disease?
Soft nodules along the hair shaft caused by Trichosporon ovoides
Sabouraud’s agar haw a low pH to inhibit bacterial growth. When is this agar primarily used?
For culturing of dermatophytes (fungi that infect keratinized tissue)
Sporothrix schenckii is common in the USA. What are the characteristics of the fungus? What populations are generally infected? How does disease appear clinically?
Dimorphic found in soil and plants, commonly infecting gardeners, florists, farmers, etc.
Disease is called Sporotrichosis appearing as a painless papule at the site of inoculation and slowly enlarges to an open sore. The fungus may spread via lymphatics.
What are the characteristics of Cryptococcus?
Non-dimorphic, encapsulated yeast found in soil contaminated by pigeon droppings. Transmission via aerosols.
What are the characteristics of Aspergillus spp.?
Septated hyphae with chains of conidia on a conidiophore. Mold in soil and plants, transmission via spores
How can dermatophytes be differentiated based on appearance?
Microsporum spp. - contain macroconidia
Trichophyton spp. - microconidia & macroconidia
Epidermophyton floccosum - microconidia
What agar is used as a differential media for Canida spp.?
CHROMager
Acidotic diabetic patients are more susceptible to what infection by what systemic fungus?
Rhinocerebal disease - Mucormycetes genera
What fungus is responsible for causing Tinea nigra (brown to black lesions on hands and feet)? How is the fungus spread? How does it appear in culture?
Hortaea werneckii spread by soil, compost, and wood. Appears with brown septated hyphae and 2-celled yeast cells
What stain is used to identify conidia and hyphae by fungi grown in culture?
Lactophenol Cotton Blue
Blood agar may be used for fungi growth. What precautions must be taken to prevent cross-contamination?
The agar must include antibiotics to prevent bacterial growth.
What are the characteristics of endemic Histoplasma capsulatum?
Spread by soil containing bird or bat guano. Intracellular yeast that proliferates in macrophages and lacks a capsule. Found in the Ohio & Mississippi Valleys.
These spores are formed by the fragmentation of hyphae
Arthroconidia
What disease caused by Candida is considered an AIDS-defining illness?
Esophageal candidiasis
What are Hyphae?
Filamentous or tubular structures of mold
What are Dematiaceous fungi?
Fungi that is black or brown pigmented
What is a mass of intertwined hyphae?
Mycelium
What disease is caused by Cryptococcus?
Cryptococcosis - dissemination through CNS causing headache, fever, stiff neck and disorientation. AIDS-defining illness
What are the general characteristics of Candida spp.?
Dimorphic, budding yeast cells with pseudohyphae. Normal flora in the mouth, GI tract, and female genital tract.
What is chromomycosis? What fungi cause the disease?
Slow-growing (years), scaly, wart-like structure on the foot or leg caused by Phialophora & Cladosporium fungi
How are dermatophytes spread? Where do they infect?
Spread by soil, animals, and people
Infect the keratinized layer of hair, skin, and nails
What methods may be used for clinical observation of fungi and/or their structures?
Preparation with KOH, Calcofluor white fluorescent stain, Gormori’s methenamine silver, gram stain
This endemic fungus is difficult to isolate, proliferates in tropic regions, and appears as a “pilot’s wheel” with a parent cell surrounded by daughter cells.
Paracoccidioides brasiliensis
This systemic mycotic fungus is common on bread and spoiled foods.
Mucorcycetes genera
What are the characteristics of Malassezia furfur complex? What is the clinical manifestation of the fungi?
Normal flora of skin in oily areas, dimorphic, lipophilic, opportunistic.
Cause of Tinea (pityriasis) versicolor (pigment change), seborrheic dermatitis, and dandruff (cradle cap)
What diseases are associated with Mucormycetes genera infection?
Rhinocerebral disease & pulmonary disease
These types of infections are caused by fungi with a black or brown pigment.
Phaeohyphomycosis infections caused by Dematiaceous fungi.
What clinical diseases are associated with Candida spp.?
Oral thrush, vulvovaginitis, cutaneous candidiasis, esophageal candidiasis, disseminated candidiasis
What is Pseudohyphae?
Hyphae-like structure formed by the incomplete budding of a daughter yeast cell from a parent cell
What types of pathogenic infections do fungi generally cause?
Opportunistic & noscomial infections
What is the common cause of Athlete’s Foot?
Trichophyton spp.
What term describes the oval-shaped, single-celled form of fungi?
Yeast
What are the characteristics of endemic Coccidioides?
Found in semiarid climates and SW USA. Transmission by inhalation of arthroconidia. In the tissue, the fungus is in a spherule containing endospores. Cause of Coccidioidomycosis (Valley Fever)
What are the four types of mycoses? Where do they cause infection?
Superficial mycoses - outermost layer or skin & hair
Cutaneous mycoses - keratinized layer of skin, hair, & nails
What are the four types of mycoses? Where do they cause infection?
Superficial mycoses - outermost layer or skin & hair
Cutaneous mycoses - keratinized layer of skin, hair, & nails
Subcutaneous mycoses - under skin by a puncture wound
Systemic mycoses - usually my opportunistic pathogens or endemic mycoses
What are the characteristics of the Mucormycetes genera?
Broad, non-septated hyphae. Ubiquitous mold. Colonize respiratory tract
What is the common name for tinea?
Ringworm
How does the fungal eukaryotic cell differ from a mammalian eukaryotic cell?
Fungal cells have a cell wall made of chitin, mannans, beta-glycans, and other carbohydrates. The cell membrane contains ergosterol rather than cholesterol found in mammalian cells.
What disease is caused by Piedraia hortae?
Black piedra - gritty nodules along with hair shaft
Fungi that grow as both mold and yeast are said to be…
Dimorphic fungi
What are the common dermatophytes?
Microsporum spp., Trichophyton spp., Epidermophyton floccosum
What are the characteristics of endemic Blastomyces dermatitidis?
Grows in damp soils. Extracellular yeast with a thick wall and broad-based budding. May be transmitted via skin.
