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144 Cards in this Set
- Front
- Back
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What is yeast?
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A form of fungi that is unicellular and reproduces through budding
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What is the appearance of yeast on agar?
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Slimy or mucoid colonies that resemble bacterial colonies
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What is the appearance of molds on agar?
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Downy, fluffy, cottony colonies
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List 6 dimorphic fungi.
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Histoplasma capsulatum
Blastomyces dermatitidis Coccidioides immitis Paracoccidioides brasiliensis Sporothrix schenckii Penicillium marneffei |
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What is the definition of dimorphic fungi?
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Mycelial fungi in nature and lab temperatures below 30 Celsius with yeast phase in human tissue or lab temperatures above 35
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What is a cause of superficial mycoses?
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Malassezia furfur (tinea versicolor)
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What is a cause of subcutaneous mycoses?
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Chromomycosis
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What is a cause of deep or systemic mycoses?
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Histoplasma capsulatum
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What is a cause of opportunistic mycoses?
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Aspergillus fumigatus
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What is the all purpose plating media used in mycology?
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Sabouraud's glucose agar
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What is inhibitory mold agar?
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It is a selective SAB agar with chloramphenicol and enrichment to inhibit bacterial growth
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What does not grow on inhibitory mold agar?
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Saprophytic fungi and dermatophytes
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What agar is used for the recovery of dimorphic pathogens?
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Inhibitory mold agar
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Which dimorphic fungi can cause disseminated infections?
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Histoplasma capsulatum
Blastomyces dermatitidis Coccidioides immitis Paracoccidioides brasiliensis |
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What does cyclohexamide do?
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It inhibits rapidly growing molds from overgrowing slow growing dimorphics
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For what is blood brain heart infusion agar used?
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To grow dimorphic pathogenic fungi such as Histoplasma capsulatum
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What is Mycosel/Mycobiotic agar?
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It is a selective SAB with chloramphenicol and cyclohexamide used for dermatophytes
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What agar is used for skin, hair, and nail specimens?
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Mycosel/Mycobiotic agar
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Which fungi are suppressed by cyclohexamide?
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Cryptococcus neoformans
Candida tropicalis Trichosporon beigelii Yeast of Blastomyces Yeast of Histoplasma |
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Is gram stain best for the detection of yeast, mold, or both?
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Yeast (stains a dark blue)
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What is the calcofluor white stain?
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Fluorescent stain that binds to keratin of both yeast and mycelial fungi
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What does India ink stain?
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The negative background
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At what temperature and how long is fungus incubated?
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30 degrees C for 4 weeks
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What method is used to observe mold microscopically?
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Lactophenol cotton blue prep
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What is the geographic distribution of Histoplasma capsulatum?
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Ohio, Missouri, and Mississippi River valleys
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What lesion is commonly seen with Histoplasma capsulatum?
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Mucocutaneous lesions
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What percentage of Histoplasma cases are subclinical?
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95%
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What is the size range of Histoplasma yeast?
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2-4 micrometers
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Which cells contain Histoplasma yeast?
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Macrophages
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What is the best test for the diagnosis of Histoplasma capsulatum in immune suppressed patients?
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Direct antigen detection in urine
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What is the gross appearance of Histoplasma on agar?
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White to brown, cottony mycelium that is a slow grower taking 2-8 weeks to grow
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What is the microscopic appearance of Histoplasma?
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Large and round (8-16 micrometer) tuberculated macroconidia with small microconidia
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What differentiates Sepedonium species from Histoplasma capsulatum?
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Sepedonium has large rough spores (7-17 micrometers) but NO microconidia
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Describe the budding pattern of the yeasts of Histoplasma capsulatum?
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Narrow neck budding
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What is the cause of the appearance of a capsule in intracellular Histoplasma capsulatum?
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Staining artifact
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What is the variant of Histoplasma capsulatum associated with skin and bone lesions in Central Africa?
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Histoplasma capsulatum var duboisis
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How is Histoplasma capsulatum var duboisis differentiated from classic Histoplasma capsulatum?
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Histoplasma capsulatum var duboisis has yeast that are 8-10 micrometers (2x the size of classic Histoplasma capsulatum)
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What is the cause of pityriasis versicolor and fungemi in neonates on IV lipid feeding?
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Malassezia furfur
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What causes the most superficial dermatomycoses?
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Malassezia furfur (tenia versicolor)
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What is needed for the growth of Malassezia furfur on culture medium?
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Oil
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What yeast is characterized by a collarette on wet prep?
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Malassezia furfur
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Is Cryptococcus sensitive to cyclohexamide?
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Yes
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What is the appearance of Cryptococcus neoformans on agar?
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Mucoid colonies
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What is a sensitive test for Cryptococcus in CSF of patients with AIDS?
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India ink
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What is a sensitive test for Cryptococcus in CSF of HIV-negative patients?
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Cryptococcal antigen
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To what is cryptococcal antigen directed?
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Capsule of Cryptococcus
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On what agar does Cryptococcus neoformans appear brown but other organisms appear white?
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Birdseed agar
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What yeast is urease positive?
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Cryptococcus neoformans
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What is the size range of Cryptococcus neoformans?
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2-20 micrometers
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How is Cryptococcus gatti distinguished from C. neoformans?
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C. gatti turns L-canavanine glycine bromthymol blue medium blue whereas it remains yellow with C. neoformans
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What is the most common candida?
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C. albicans
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Which candida are resistant to fluconazole?
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C. glabrata
C. krusei C. tropicalis |
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Which candida is a pathogen of children and IV lines?
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C. parapsilosis
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Which candida does not form pseudohyphae?
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C. albicans
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What are the characteristics of Candida albicans?
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Grows in 24-48 hours
Pasty white bacterial-like colonies |
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Which candida forms chlamydospores?
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C. albicans
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Which candida form germ tubes?
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Candida albicans
Candida dubliniensis |
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What is the size range for Candida glabrata?
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2-4 micrometers
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What is the size range of Candida species?
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8-10 micrometers
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Which candida appears green on ChromAgar Candida?
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C. albicans
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Which candida appears blue on ChromAgar Candida?
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C. tropicalis
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Which candida appears white on ChromAgar Candida?
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C. parapsilosis
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Which candida appears pink on ChromAgar Candida?
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C. glabrata
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Which candida provides a false diagnosis of C. albicans if the germ tube test is incubated for more than 4 hours?
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C. tropicalis
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Histoplasma capsulatum
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Histoplasma capsulatum
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Histoplasma capsulatum
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Histoplasma capsulatum
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Mucocutaneous lesion caused by Histoplasma capsulatum
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Cryptococcus neoformans
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Cryptococcus neoformans
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Cryptococcus neoformans
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Birdseed agar
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Cryptococcus neoformans (brown)
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Urease positive yeast
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Cryptococcus neoformans
Trichosporon species |
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Test?
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Germ tube test
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Yeast positive for germ tube test
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Candida albicans
Candida dubliniensis Canadida tropicalis (if incubated >4 hours) |
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What yeast?
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Candida glabrata
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Candida albicans
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Candida dubliniensis
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What yeast?
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Candida parapsilosis
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Candida albicans ("feet")
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Malassezia furfur
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Review
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What is the geographic distribution of Blastomyces dermatitidis?
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Ohio and Mississippi River valleys
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What does Blastomyces dermatitidis cause?
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Pulmonary disease that can disseminate to skin and bone
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What mold is characterized by lollipop-shaped conidia?
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Blastomyces
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What temperature and what length of time is need to grow out the mycelial form of Blastomyces dermatitidis?
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30 degrees C for 2-3 weeks
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What temperature and what length of time is need to grow out the yeast form of Blastomyces dermatitidis?
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37 degrees C for 4 weeks
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What is a mimicker of Blastomyces?
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Chrysosporium
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What type of yeast budding is seen with Blastomyces dermatitidis?
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broad-based budding with double contoured wall
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What is the appearance of Blastomyces on agar?
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Fluffy white and buff colored
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What is the size range of the yeast of Blastomyces dermatitidis?
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8-20 micrometers
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What is the geographic distribution of Coccidioides immitis?
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Southwest USA, Mexico, South America in Sonoran life zone (desert sands)
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What percentage of Coccidioides immitis infections are chronic?
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95%
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What is the most deadly dimorphic fungi?
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Coccidioides immitis
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What does Coccidioides immitis cause?
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Focal pulmonary disease, but can become disseminated
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What are the risk factors for dissemination of Coccidioides immitis?
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Immunodeficiency
Darker ethnic groups Pregnancy |
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What temperature and what length of time is needed to grow the mycelial form of Coccidioides immitis?
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30 degrees C for 2-3 days
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What is the appearance of Coccidioides immitis on agar?
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White waxy/wooly colonies
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What is a good description for Coccidioides immitis?
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Septated hyphae with chains of thick waled barrell shaped arthroconidia with dead cells (cleared out) in between
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What is a mimicker of Coccidioides immitis?
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Malbranchea
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What is unique about Coccidioides immitis compared to other dimorphic fungi?
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The yeast phase cannot be grown in the lab and is only seen in tissue
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What is the appearance of Coccidioides immitis yeast in tissue?
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10-80 micrometer spherules with endospores
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What does Rhinosporidium seeberi cause?
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Oral or nasal mass lesions
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What distinguishes Rhinosporidium seeberi from Coccidioides immitis?
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The spherules of Rhinosporidium seeberi contains endospores 2X the size of those of Coccidioides immitis
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What is the geographic distribution of Paracoccidioides brasiliensis?
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Brazil, Venezuela, Columbia in soil
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Is there a male or female predominance for Paracoccidioides brasiliensis?
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Male (95%)
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What fungi has a marked male predominance?
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Paracoccidioides brasiliensis
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What does Paracoccidioides brasiliensis cause?
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Pneumonia
Disseminated infection Extrapulmonary lesions on face and oral mucosa |
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What is the characteristic appearance of the yeast form of Paracoccidioides brasiliensis?
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Large yeast (10-30 micrometer) with multiple daughter buds (2-10 micrometers) with the appearance of a mariner's wheel
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List 4 causes of subcutaneous fungal infections
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Mycetoma
Chromomycosis Phaeohyphomycosis Sporotrichosis |
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What are other names for mycetoma?
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Madura Foot
Maduromycosis |
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What is the geographic distribution of mycetoma?
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Hot temperate parts of the world
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What are the criteria for diagnosing mycetoma?
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Lesions leading to swollen extremities
Draining sinuses Sulfur granules in tissue and drainage |
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What are the 2 types of mycetoma?
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Actinomycotic
Eumycotic |
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What is the most common cause of mycetoma?
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Nocardia species
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What causes eumycotic mycetoma?
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Black molds
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What type of mycetoma are 98% of cases?
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Actinomycotic
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What is the most common cause of actinomycotic mycetoma?
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Nocardia species
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What is a good description of Nocardia?
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Gram positive filamentous branching rods
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What is the staining pattern of Nocardia?
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Gram positive
Modified acid-fast positive |
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What is the appearance of Nocardia on agar?
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Dry and crumbly
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What mold has a characteristic musty smell?
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Nocardia species
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How long does it take to grow Nocardia on agar?
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3-5 days
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List 6 fungi that cause eumycotic mycetoma
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Cladophialophora carrionii
Cladophialophora bantiana Phialophora verrucosa Fonsecaea pedrosoi Exophiala species Wangiella species |
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List 6 fungi that cause chromomycosis
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Cladophialophora carrionii
Cladophialophora bantiana Phialophora verrucosa Fonsecaea pedrosoi Exophiala species Wangiella species |
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How is actinomycotic sulfur granules distinguished from eumycotic sulfur granules?
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The edges of actinomycotic sulfur granules has thin filamentous bacteria whereas edge of eumycotic sulfur granules has thick mycelial hyphae
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What are the characteristics of chromomycosis?
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Wart like lesions in cutaneous tissue
Sclerotic bodies in tissue Growth of dark/pigmented fungi |
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What type of infection is associated with sclerotic bodies?
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Chromomycosis
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What is a good description of sclerotic bodies?
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"Copper pennies"
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What does Prototheca wickerhamii cause?
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Skin lesions or nodules
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What is a characteristic finding of Prototheca wickerhamii?
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Morula body
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What is phaeohyphomycosis?
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An infection caused by traumatic implantation of dark fungi into subcutaneous tissue that lacks sulfur granules and sclerotic bodies
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What is Prototheca wickerhamii?
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Algae without chlorophyll that can be found in immunocompromised patients
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List 4 types of sporulation patterns of black molds
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Rhinocladiella-like
Cladosporium-like Phialophora-like Acrotheca-like |
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Describe Rhinocladiella-like sporulation
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"Fern tree" with natural brown colors
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Describe Phialophora-like sporulation
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"Flower pot" with natural brown color
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Describe Cladophialophora-like sporulation
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"Stringy filaments"
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What black mold causes brain infections?
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Cladophialophoria bantiana
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Which black mold is commonly found in showers?
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Alternaria
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Describe Alternaria
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"Chain of hand grenades"
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Describe Bipolaris
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"Hockey stick"
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What is a very invasive dematiaceous fungi to skin, nasal sinuses, bone, and brain?
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Bipolaris
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What causes the curve in Curvularia?
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The center cell is the largest cell and causes a curve.
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