CLS09 - Dematiaceous molds, yeasts, antifungal

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  1. Dematiaceous molds (general) - meaning, disease, habitat, classification
    • mean: brown-pigmented
    • disease: superficial and subcutaneous mycoses
    • habitat: ubiquitous in nature (humans and animals accidental hosts)
    • classification: slow growing (7-10 days) and rapid growing (<7 days)
  2. disease and cause - Tinea nigra, black piedra, mycetoma, chromoblastomycosis, phaeohyphomycosis
    • tinea nigra: skin infection caused by Hortaea werneckii
    • Black piedra: hair/scalp infection caused by Piedraia hortae
    • Mycetoma: chronic granulomatous infection involving lower extremities (bacterial or fungal)
    • Chromoblastomycosis: chronic infection acquired by traumatic innoculation
    • lesions reveal sclerotic bodies, resemble copper pennies
    • Phaeophyphomycosis: infections from brownish yeastlike cells, pseudohyphae, or hyphae
  3. Hortea werneckii - disease, what is found in tissue
    • Tinea nigra (skin infection)
    • Tissue contains hyphal fragments, budding yeast
  4. Piedraia hortae - disease, what is found in tissue
    • Black piedra (hair infection)
    • Tissue contains asci-containing nodules cemented to hair shafts
  5. What are the two types of fungal mycetomas? Where are they found?
    • White grain and Black grain
    • Infections mostly in tropical/subtropical regions w/ those who have outdoor occupations
  6. Pseudallescheria boydii - disease, speed, unique colony, reproduction, unique micro
    • disease: White grain mycetoma
    • speed: rapid
    • colony: white mouse fur (reverse is brownish)
    • repr: Asexual = Scedosporium apiospermum (culture-based, graphium stage)
    • sexual = cleistothecia
    • micro: lollipop-like
    •  Image Upload 1
  7. Acremonium - disease, unique colony, unique micro
    • disease: white grain mycetoma
    • colony: compact/glabrous -> felt-like, pale rose
    • micro: extremely delicate, septate hyphae, oblong conidia
    • Image Upload 2
  8. Curvularia - disease, unique micro
    • disease: black grain mycetoma
    • micro: large brown conidia, 4 cells, appear curved due to 3rd cell swelling
    • Image Upload 3
  9. Cladosporium - disease, where in tissue, unique colony, unique micro
    • disease: Chromoblastomycosis (copper penny lesions)
    • saprophytic contaminant
    • tissue: subcutaneous tissue
    • colony: greenish/brown w velvety nap, reverse is black
    • micro: produce conidial chains w/ dark spots at site of attachment
    • Image Upload 4
  10. Phialophora - disease, where in tissue, unique micro
    • disease: Phaeohyphoycosis
    • Chromoblastomycosis (copper penny lesions)
    • tissue: subcutaneous, joints
    • micro: Phialides are vase shaped w/ flared cup collaretts
    • Image Upload 5
  11. Fonsecaea pedrosoi - disease, where in tissue, unique micro
    • disease: Chromoblastomycosis (#1 cause)
    • Copper penny lesions in tissue samples
    • tissue: subcutaneous tissue, brain and lung tissue
    • micro: 4 types of conidiation (difficult to ID)
    • Fonsecaea-type = (tertiary chains of conidia, "asterisks")
    • Rhinocladiella type (swollen denticles, ovoid conidia)
    • Phialophora type (vase-like w/ conidiospores on top)
    • Cladosporium type (large primary shield w/ short branching chains of oval conidia)
    • ****USE MALDI OR PCR!!!!
  12. Alternaria - disease, unique colony, unique micro
    • disease: Phaeohyphomycosis
    • saprophytic contaminant
    • colony: fast grower, grayish white/whooley -> brown w/ light border
    • micro: "alternating conidia" "drumsticks" "pinecones"
    • Image Upload 6
  13. Bipolaris - disease, unique micro
    • disease: Phaeohyphomycosis
    • micro: conidiophers bent where conidia are attached "zig zag"
    • Image Upload 7
  14. Pneumocystic jiroveci - disease, stages, differs from other fungi, transmission, common hosts, spp, specimen, morphology
    • disease: Pnemocystis pneumonia (PCP)
    • affects immunocomp
    • inhaled cyst replicates extracellularly -> inflammatory response
    • stages: cyst (diagnostic), precyst (sporozoite), trophozoite
    • differs: cell membrane contains cholesterol
    • trophozoite form susceptible to osmotic disturbance
    • one-two copies of ribosomal subunit gene
    • transmission: unknown
    • hosts: most common opp infection in HIV/AIDS
    • spp: P. jiroveci = humans, P. carinii = rodents
    • specimen: brochoalveloar lavage fluid, induced sputum, lung biopsy
    • trophozoite: predominant form, difficult to visualize *red
    • Cysts: spherical, do not bud, intracystic bodies *green
    • Image Upload 8
  15. Information about yeasts (structure, repr, morph, imp. spp)
    • Eukaryotic
    • unicellular
    • Asexual repr: via budding
    • sexual repr: via ascospores/basidiospores
    • Germ tube: tubular outpouch of cell wall
    • Pseudohyphae: elongated buds that form more buds
    • *full cleavage, plus 'pinched' appearance
    • spp: Candida (most common opportunistic fungal infection)
    • Cryptococcus (very common AIDS/HIV)
    • Trichosporon
    • Malassezia
  16. What are the non-albicans candida infections?
    • albicans is the vast majority (thrush, vulvovaginitis, onychomycosis, paronychomycosis, systemic infections, UTIs, heart and lung infection)
    • C. glabrata, krusei, and tropicalis in certain populations (older adults, oncology pts, neonatal ICU pts)
  17. Candida - stains, unique colony, biochem ID, CHROMagar, C. albicans unique
    • stains: strongly gram+
    • colony: smooth, waxy, creamy colonies (not a mold)
    • biochem: fermentation of carbohydrates
    • PNA-FISH
    • beta-galactose-aminidase and 1-proline aminopeptidase
    • CHROM: C. albicans - green, round
    • C. glabrata - light/dark mauve
    • C. tropicalis - smooth, blue colonies w/ dk brown agar halo
    • C. krusei - pink, rough, crenated colonies w/ pale edges
    • unique: Positive germ tube, Green on CAC, cornmeal agar growth
  18. Cryptococcus neoformans - disease, virulence factor, stains, cultivation, unique colony, unique ID
    • disease: pulmonary infection -> CNS (esp in immunocomp) -> papular skin lesions, endocarditis, hepatitis, renal infection
    • vir: polysaccharide capsule protects from environment and phago
    • stains: India ink defines the capsule (appears as thick-walled yeats)
    • Image Upload 9
    • cultivation: routine fungal media w/o cyclohexamide
    • colony: mucoid (from capsule)
    • IDrapid urease positive
    • pigment on niger seed agar
  19. Trichosporon - disease, unique micro, unique ID
    • disease: trichosporonisis, skin lesions, brain abscess, resp infections
    • white piedra in immunocomp
    • micro: numerous arthroconidia, few blastoconidia
    • Image Upload 10
    • IDrectangular arthroconidia w/ round ends
    • urease positive
  20. Malassezia - diseases, unique micro, cultivation
    • M. furfur: Tinea versicolor (brownish scaly lesions on whitey, light lesions on darky)
    • *disseminated infection in children
    • M. pachydermatis: fungemia in immunocomp
    • *recovered from skin lesions
    • microspaghetti and meatballs hyphae
    • "bowling pin" yeast morphology
    • cult: requires olive oil overlay

  21. Who develops antifungal stds? What are the 3 guideline documents?
    • CLSI
    • M27-AS: broth dilution of yeasts
    • M38-A: broth dilution of mold
    • M44-A: disk diffusion of yeasts
  22. Polyene Macrolide Antifungal Agents - structure, examples
    • contain multiple conjugated double bonds and one to three ring structures
    • amphotericin B
    • Nystatin
    • Griseofulvin
    • 5-Fluorocytosine (synergistic w/ amphotericin B)
  23. Amphotericin B agents - function, resistant fungi
    • bind to ergosterol in cell membrane
    • IV or topical
    • Aspergillus are resistant
  24. Azole antifungal agents - function, common agents
    • disrupt integrity of cell membrane, inhibit ergosterol synthesis
    • clotrimazole and miconazole
    • fluconazole
    • ketoconazole
    • itraconazole
    • voriconazole
  25. Echinocandin agents - function, types, resistant
    • inhibit glucan synthesis
    • Caspofungin (C. neoformans is resistant)
    • Micafungin
    • Anidulafungin
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CLS09 - Dematiaceous molds, yeasts, antifungal
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CLS09 - Dematiaceous molds, yeasts, antifungal
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