Microbiology Final Exam Flashcard
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| G eneral characteristics of fungi |
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| Chitin in cell wall, ergosterol in cell membrane, reproduction by means of spores, no chlorophyll, heterotrophic and not susceptible to antibacterial agents. |
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| Explain the purpose of cyclohexiamide in fungal media |
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| Cyclohexiamide is an antibiotic for inhibiting protein synthesis of saprobic fungi on sabouraud dextrose agar |
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| Germ tube |
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(botany) a slender tubular outgrowth from a spore in germination. |
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| KOH wet prep |
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| KOH dissolves human cellular elements and debris, which allows for easier visualization of fungal elements |
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| Calcoflour white prep |
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| Calcoflour binds to chitin in fungal cell wall, fluorescence occurs at 400nm, fungal elements fluoresce blue-white |
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| In vitro hair penetration test |
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| some fungi will penetrate the hair shaft, Trichophyton mentagrophytes is positive, Trichophyton rubrum is negative |
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| Tease mount |
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| take mold from agar plate, and put it on a slide with a drop of lactophenol blue, used to identify morphologic structures of mold |
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| Slide culture |
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| cut a small block of sterile agar, place on a sterile slide in a huminidity chamber, inoculate the four corners of the agar with fungi and apply a coverslip to the top of the agar. Ater incubation remove coverslip and palce on a new slide with a drop of lactopenal blue, observe for morphologic characteristics. |
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| Blastoconidia |
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| asexual reproduction of yeast, budding yeast cells from weakened out-pouching of cell wall |
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| Conidiophore |
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| specialized hyphal structure that serves as a stalk on which conidia are formed |
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| Mycelium |
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| mould characteristic, growing hyphae that become intertwined to form a loose network that can penetrate the substrate to obtain necessary nutrients |
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| Psuedohypha |
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| yeast buds elongate, fail to dissociate, and form subsequent buds, looks like a link of sausage, cell wall constrictions rather than septations |
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| Rhizoid |
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| root-like structures that appear and anchor the organism to the agar surface, used in identification of zygomycetes |
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| Saprophyte |
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| living on dead or decayed organic mater, characteristic of most of the fungal organisms that cause human disease |
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| Septa |
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| cross walls in hyphae |
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| Sporangiophore |
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| supporting structure at which each sporangium is formed at the tip of, usually connected to one another by septate hyphae |
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| Spore |
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| A minute, typically one-celled, reproductive unit capable of giving rise to a new individual without sexual fusion |
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| Dematiaceous |
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| presence of pigmentation within the hyphae of molds |
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| Hyaline |
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| absence of pigmentation within the hyphae of molds |
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| Dimorphism in fungi |
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| can grow as yeast at body temp and as mould at room temp |
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| Clinical significance of dimorphism- |
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| allows organism to survive and infect humans inside their bodies as opposed to subcutaneous |
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| Dimorphic fungi |
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| Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, paracoccidiodes brasiliensis, Sporothrix schenckii, and Penicillium marneffei |
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| Mycoses |
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| fungal infection that causes disease |
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| Mycotoxicoses |
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| toxic secondary disease caused by toxin from fungi |
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| Mycetoma |
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| usually on hands and feet, chronic infection characterized by swollen tumor-like lesions that yield granular pus through draining sinuses, the granules are masses of compact mycelia |
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| Tinea |
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| infections of the skin or nails caused by dermatophyte fungi, outer ring is active, progressing infection, with central healing within the ring |
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| Chromoblastomycosis |
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| subcutaneous mycoses in which there is a localized cutaneous and subcutaneous infection where the tissue turns into rounded sclerotic bodies, called copper pennies |
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| Phaehyphomycosis |
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| term to describe any infection caused by a dematiacious organism, can be subcutaneous, localized, or systemic infections |
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| How do you tell a yeast from a mould? |
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| Yeast are single vegatative cells called blastoconidia, while moulds are filamentous fungi that can have mycelium, hyphae and rhizoids |
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| Conidia |
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| asexual reproduction that occurs on the side or end of hyphae or conidiophore |
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| Macroconidium |
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| larger of 2 types of conidia in a fungus that produces 2 sizes of conidia |
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| Microconidium |
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| smaller of 2 types of conidia in a fungus that produces 2 sizes of conidia |
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| Annellide |
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| a cell that produces & extrudes conidia; tapers & lengthens with each condidum |
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| Arthroconidium |
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| an asexual spore formed by the breaking of hyphae at the point of septation |
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| Philalide |
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| a cell that produces & extrudes conidia; does not taper or lengthen with each condidium |
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| Sporandiospore |
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| asexual spore produces within a sporangium |
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| Sproangium |
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| a closed sac-like structure in which asexual spores are formed by cleavage |
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| Zygomycota |
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| sexual reproduction occurs with the production of zygospores |
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| Type of Zygomycota |
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| Mucor, Rhizopus, Absidia |
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| Ascomycota |
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| sexual spores produced within a sac-like structure knowns as an ascus |
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| Types of Ascomycota |
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| Microsporum, Trichophyton, Pseudallescheria |
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| Basidiomycota |
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| sexual spore formed on a structure known as a basidium |
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| Types of Basidiomycota |
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| Filobasidiella neoformans (Cryptococcus neoformans) |
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| Fungi Imperfecti |
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| no known sexual mode of reproduction |
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| Superficial mycoses |
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| confined to the outermost layer of skin or hair |
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| Cutaneous mycoses |
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| affect the keratinized layer of skin, hair or nails |
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| Subcutaneous mycoses |
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| involve deeper skin layers, including muscle & connective tissue |
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| Systemic mycoses |
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| affect internal organs or deep tissues of the body |
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| Types of specimens (8) |
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| Hair Skin Nails Blood & bone marrow CSF Abscess fluids & wound exudates Respiratory specimens Urogenital & fecal specimens |
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| Ways to perform direct microscopic examination (4) |
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| KOH preparations KOH with calcofluor white India Ink Tissue stains |
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| Antibiotics used on media |
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| Chloramphenicol (bacteria) Cyclohexamide (saprobic fungi) |
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| Incubation for fungal media |
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| 25-30 C for 4 weeks |
