MICROBIO

• Fungi are eukaryotes with a true nucleus, are a chlorophyllous organism that lacks chlorophyll and is an obligate aerobe, inhabiting water, soil, and decaying organic debris.
• Fungi belong to the plant kingdom without roots and stems and are referred to as Thallophytes.
• Fungi have chitin on their cell wall and ergosterol in their cell membrane, which resembles keratin in function.
• Fungi grow at 37 o C at neutral pH.
• Fungi produce toxins, such as aflatoxin, which is a hepatotoxin produced by A. flavus.
• Yeast are unicellular, most reproduce asexually by budding, and their colonies are moist, creamy, opaque, and pasty in plated media.
• Most yeast species have similar microscopic and colonial morphology and require physiologic/biochemical tests for identification.
• Yeast grow at 35 - 37 o C.
• Trichophyton infects skin, hair, and nails.
• Trichophyton violaceum produces violet-colored colonies.
• Trichophyton schoenleinii produces white and wrinkled colonies and has many antler hyphae (favic chandeliers).
• Trichophyton verrucosum produces macroconidia appearing like a "rat-tail" and is positive in the urease test.
• Trichophyton tonsurans is responsible for the epidemic form of Tinea capitis and produces balloon-shaped microconidia or matchstick form.
• Floccosum produces smooth-walled macroconidia appearing like a beaver's tail and does not produce microconidia, making it unique among Trichophyton species.
• Mentagrophytes produces star-shaped powdery colonies in Potato dextrose agar.
• Members of the Trichophyton genus do not usually fluoresce under UV light of a Wood's lamp.
• Mentagrophytes is the most common cause of athlete's foot and produces microconidia in grape-like clusters (globose appearing).
• Trichophyton rubrum produces tear-shaped microconidia.
• Mold are multicellular, filamentous, and their colonies are fluffy, cottony, wooly, or powdery at room temperature.
• A positive result in the Exoantigen test indicates the presence of precipitin bands.
• Incubate yeast colonies with 0.5 mL serum, incubate at 35 - 37 o C for 3 hours.
• Corn Meal agar - chlamydospore test is a method for the identification of yeast.
• PCR is a method for the identification of yeast.
• Germ tube screening is a method for the identification of yeast.
• CHO assimilation is a method for the identification of mold.
• Place a drop on a slide and do microscopy.
• Biochemical tests are a method for the identification of yeast.
• Culture SDA 28 - 30 days RT is a method for the identification of mold.
• Sero logy is a method for the identification of yeast.
• Microscopy is a method for the identification of genus and species of mold.
• Stain LPCB is a method for the identification of mold.
• Trichosporon and Geotrichum spp are examples of mold species.
• Blastoconidia, Pseudohyphae, Arthroconidia, Cryptococcus, and Candida spp are examples of yeast species.
• Mold grow at 25 - 30 o C (room temperature).
• Some fungi exist either as yeasts or molds, while others exist as both.
• Thermally dimorphic fungi have dimorphism that is thermally dependent, such as C. immitis.
• Polymorphic fungi have both yeast and mold forms in the same culture.
• Hyphae is the fundamental unit of fungi, and when many hyphae are joined, they form mycelium, which accumulates during active growth in the mold form.
• Aseptate (coenocytic) hyphae have no crosswalls (no divisions), all are septated except Zygomycetes.
• Septate hyphae are divided into cells by crosswalls.