Tubular filaments that are the microscopic units of the fungi and intertwine to form the mycelium.
Intertwining structure of fungi composed of tubular filaments or hyphae.
Septate hyphae
Hyphae with separations or walls.
Aseptate hyphae
No walls or septate.
Asexual conidia produced by formation of conidia by simple budding from mother’s cells hyphae, or pseudohyphae.
Thick walled asexual conidia that are formed during unfavorable conditions and germinate when environment improves; greater in diameter than hyphae and may be observed at hyphal tip, within the hyphae, and on the sides of the hyphae.
Asexual spores formed by fragmentation of mycelia into rectangular barrel shaped or cask shaped thick walled spores.
Asexual spore contained in a saclike structure in which spores are formed and held (sporangium); the sporangium is housed in a specialized hyphal stalk or sporangiophore.
Type of specialized spore involved in sexual reproduction of some fungi in which two to eight spores are contained in a sac like ascus.
Those members of the plant family that possess true nuclei lack stems and roots, do not possess chlorophyll, and absorb nutrients from the environment.
Dimorphic fungi
Fungi that possess both a yeast phase at 37oC and a mold or mycelial phase at 25oC.
Fungi imperfecti
Imperfect fungi that do not exhibit a sexual phase and produce spores asexually from the mycelium.
Asexual spores produced by some fungi either singly or multiply in long chains or clusters by specialized hyphae known as conidiophores.
Large multicellular club oval or spindle shaped asexual fungal spores that are usually septate.
Small unicellular round elliptical or piriform asexual fungal spores.
Asexual fungal spores contained in a sac or sporangium that are produced terminally on sporangiophores or aseptate hyphae.
Division in the botanical taxonomy that includes most medically important fungi characterized by septate hyphae and asexual reproduction.
Fungal infection of the hair involving the inside of the hair shaft.
Fungal infection of the hair shaft involving the outside of the hair shaft.
Mold phase
Mycelial phase of a dimorphic fungus that is observed on Sabouraud’s dextrose agar at 25C. The saprophytic phase is usually seen in nature.
Yeast phase
Yeast phase of a dimorphic fungus that is observed in tissue or invasive in vivo and grows on enriched media at 37oC.
Vegetative portion
The mycelium consists of a thallus (vegetative portion) which grows in or on a substrate and absorbs water and nutrients.
Reproductive area
The aerial portion with fruiting bodies.
Sexual reproduction
Reproduction by fungi involving ascospores (example). Requires the formation of a special structure so that fertilization or nuclear fission can occur.
Sexual reproductive spore in some fungi that involves fusion of cells from two separate non-identical hyphae.
Sexual reproductive spore of some fungi that involves the fusion of two identical cells arising from the same hyphae.
Type of specialized spore involved in sexual reproduction of some fungi; the spores are contained in a club shaped basidium.
Dermatiaceous fungi
A group of dark slow growing fungi that are found on vegetation and are associated with subcutaneous mycoses, including the development of chronic warty tumor like lesions of the feet and lower legs.
Best observed from the reverse side and may be flat, heaped, or folded.
Best observed in a cross section and it is usually related to the length of the aerial hyphae.
Type of subcutaneous fungi infection caused by the dermatiaceous fungi; generally these infections are transmitted thru a puncture wound or skin trauma involving fungus contaminated vegetation.
Chronic granulomatous infection of the cutaneous and subcutaneous tissues and bone characterized by tumor like deformities of the subcutaneous tissue with abscesses, draining sinuses, and granulomatous pus.
Darkly pigmented molds.
Hyaline mold (nonpigmented). Opportunist infection. Found in soil and vegetation.
Saline wet mount
Quick simple method to observe fungal elements including budding yeast, hyphae, and pseudo hyphae.
Lactophenol cotton blue (LCB)
Used to visualize microscopic fungal morphology by imparting a blue color to the cell walls.
KOH Preparation (Potassium Hydroxide)
Dissolve keratin in skin hair and nail specimens to observe the fungal elements in the specimen.
A brightening agent added to KOH to bind chitin in the fungal cell wall and provides excellent contrast in the preparation when examined with a fluorescent microscope.
India ink
The nigrosin prep to identify the capsule of the Cryptococcus neoformans organism in CSF.
Silver stain
Methenamine silver nitrate stain, which is useful for the screening of clinical specimens providing good contrast and staining for the fungal elements. Fungi appear outlined in black against a pale background.
Periodic acid Schiff (PAS)
Stains the hyphae of molds and also some yeast by oxidizing the hydrosol in the carbohydrates of the cell walls of the organisms to form aldehydes, which react with fuschin dye and form a pink purple complex.
typical general guidelines for fungal specimen collection techniques:
Very similar to those for bacterial infections. Includes the use of sterile collection methods and devices to avoid contamination and provide sufficient quantity for culture.
Sabouraud Dextrose Agar (SDA)
General isolation medium with peptone and glucose.
Dermatophyte test medium (DTM)
Used for the recovery of dermatophytes from specimens contaminated with fungi or bacteria.
Brain heart infusion (BHI)
Useful for isolation of agents of systemic mycoses. It is most useful in the isolation of pathogenic fungi from sterile specimens.
Sabouraud Dextrose Agar with Cycloheximide & Chloramphenicol (SDA-CC)
contains cycloheximide which inhibits many saprophytic contaminating fungi while the chloramphenical is a bacterial inhibitor.
Tease mount
Tease preparation of a wet mount with Lactophenol blue in which a portion of actively growing fungus is examined.
Slide culture
Culture prepared on agar which is on a slide.
Germ tube
Serum with inoculated specimen examined after 2 hour incubation in CO2 to view germ tubes of yeast.
Carbohydrate assimilation
Can provide a definite identification for yeast and yeast like organisms.
Rapid Urease
The production of the enzyme urease is useful in the preliminary identification of mainly yeast.
BHI with antibiotics
Isolation of pathogenic fungi exclusive of dermatophytes. Useful for specimens that may be contaminated with bacteria or saprophytic fungi
BHI biphasic
Recovery of fungi from blood or bone marrow.
Mycosel agar
Isolation of hair, nail and skin infections specimens similar to DTM.
Birdseed agar
For isolation for Cryptococcus neoformans which produces phenol oxidase breaking up the medium causing growth of brown melanin colonies.
Cornmeal agar
Stimulation of conidia and chlamydospore (chlamydoconidia) production in Candida species. Used to identify Candida albicans.
Potato dextrose agar
Stimulation of conidia production in the fungi.
Rice medium
For identification of M. audouinii.
Trichophyton agar
Nutritional requirement for differentiation of Trichophyton.
Urea agar
Detection of urease production by Cryptococcus neoformans and differentiation of Trichophyton mentagrophytes from Trichophyton rubrum.
Tinea barbae
typical infection site
Ringworm of the beard.
Tinea capitis
typical infection site
Ringworm of the head/scalp.
Tinea corporis
typical infection site
Ringworm of the body
Tinea crusis
typical infection site
Ringworm of the groin.
Tinea pedis
typical infection site
Ringworm of the foot or athlete’s foot.
Tinea unguium
typical infection site
Ringworm of the nails.
Microsporum audouinii
macroscopic and microscopic descriptions
Cottony and white, rare conidia, form chlamydoconida like swellings terminally on hyphae. Once a leading cause of tinea capitis in children. Fluoresces with Wood’s light.
Microsporum canis
macroscopic and microscopic descriptions
Macroconidia are spindle shaped with thick walls, spiny ends, and may be elongated. Colonies are fluffy and white; reverse is lemon-yellow. Causes ringworm in cats, dogs, and other animals.
Microsporum. gypseum
macroscopic and microscopic descriptions
Thick walled conidia. Forms tan colonies. Found in soil.
Epidermophyton floccosum
macroscopic and microscopic descriptions
Smooth, thin walled macroconidia. Yellow to yellow-tan small colonies.
Trichophyton mentagrophytes
macroscopic and microscopic descriptions
Macroconidia are thin walled, smooth, and cigar shaped. Produced singly on hyphae. Rapid grower compared to other dermatophytes. Produces flat white cream colored colonies with a red brown underside.
Trichophyton rubrum
macroscopic and microscopic descriptions
Produces white fluffy granular colonies with a deep cherry red or burgundy pigment on the underside. Hard to find macroconidia. Typically see microconidia on hyphae.
Trichophyton tonsurans
macroscopic and microscopic descriptions
Forms rust colored pigment on reverse side of agar. Agent of epidemic tinea capitis in children (including U.S.).
Germ tubes:+
C. albicans
Wide capsules
Blastoconidia present
Candida sp., Saccharomyces, Cryptococcus sp.,Rhodotorula
Arthroconidia present
Urease: +
Cryptococcus sp., Rhodotorula
Terminal chlamydo
C. albicans
Red pigmented on SAB
typical clinical significance
Causes blastomycosis.
Involves skin, lung, and kidney infections.
Produces flu-like symptoms leading to pulmonary, skin, and organ involvement. May be rapidly fatal. Known as Gilchrist’s disease, North American blastomycosis, and Chicago disease.
typical clinical significance
Causes Coccidioidomycosis.
Involves inhalation of arthroconidia of the dimorphic fungus.
Produces pulmonary involvement and allergic reactions.
typical clinical significance
-Causes histoplasmosis (also called reticuloendothelia cytomycosis, cave disease, spelunker’s disease, and Darlings disease).
-Produces an infection caused by inhalation of microconidia in soil contaminated with excreta from birds found in the Mississippi river valley. -Involves lungs, liver, and spleen. -Organisms may remain in the host for years (may be reactivated).
typical clinical significance
Causes paracoccidioidomycosis. Produces a chronic fungal infection caused by P. brasiliensis and is characterized by ulcers of the mouth and lymph node involvement. Prefers cooler areas of the body to grow (will spread to other areas of the body if immunocompromised).
Sporothrix schenckii
typical clinical significance
Causes lymphocutaneous sporotrichosis a chronic subcutaneous fungal infection characterized by skin ulcers, subcutaneous nodules, and lymphatic infection. Found in soil and decaying vegetation.
Fonsecaea pedrosoi
typical clinical significance
Causes Chromoblastomycosis of the feet and lower legs.
Penicillium marneffei
typical clinical significance
Only true pathogen in this genus. Common cause of systemic infection (organs and skin lesions) in immunocompromised patients. Dimorphic. Yeast like cells in body. Mold form may have green aerial hyphae and reddish-brown vegetative hyphae with a red pigment.
Sporothrix schenckii
typical microscopic identify characteristics
Small, cigar shaped yeast at 35oC. Room temperature culture shows conidia in a rosette pattern at the ends of conidiophores.
Histoplasma capsulatum
typical microscopic identify characteristics
Small, round, and oval within monocytes and neutrophils on peripheral or bone marrow smears. Yeast at 35oC culture. Tuberculate macroconidia at room temperature culture.
Blastomyces dermatitidis
typical microscopic identify characteristics
Round, oval yeast with broad based budding at 35oC. Room temperature culture shows microconidia (not diagnostic).
Paracoccidioides brasiliensis
typical microscopic identify characteristics
Yeast at 35oC culture. Multiple budding yeast cells (mariner’s wheel) observed at room temperature culture
Coccidioides immitis
typical microscopic identify characteristics
Large thick walled round spherules with endospores on tissue prep (may see at 37oC culture). Produces alternating staining arthroconidia (disjunctor cell) on culture.
State the division of fungi causing the majority of fungal infections:
typical length of time fungal cultures are minimally held:
Fungal cultures minimally held at least 2 to 4 weeks.
typical macroconidia for:
Microsporum canis
Multiseptate macroconidia.
typical macroconidia for:
Trichophyton mentagrophytes
Smooth club shaped thin walled macroconidia with 8-10 septate.
typical macroconidia for:
Histoplasma capsulatum
Large thick walled knobby tuberculate macroconidia.
typical macroconidia for:
Epidermophyton floccosum
Numerous club shaped smooth walled with 2-4 septate.
microscopic identification
Like Rhizopus but the sporangiophores arise between nodes from which rhizoids are formed.
microscopic identification
Like rhizopus with no rhizoids.
microscopic identification
Branching septate hyphae that terminate in a conidiophore that expands into a large spherical vesicle covered with stalks (sterigmata).
microscopic identification
Large broad nonseptae hyphae producing horizontal runners or stolons attaching at rhizoids with sporangiophores arising in clusters terminating in sporangia.
microscopic identification
Septate hyaline hyphae with brush like conidiophores which give rise to phialides
microscopic identification
Septate dermatiaceous conidiophores that branch with chains of brown conidia which are muriform and tapered
microscopic identification
Two celled or multi-celled structures, smooth walled, fusiform, macroconidia resembling a banana.
Malassezia furfur:
-clinical significance
-common name given to the infection
-significant microscopic appearance
-significant growth characteristics:
Causes tinea versicolor.
Appears as tight clusters of spherical yeast like cells.
Grows on SDA with olive oil in 2-4 days at 30oC producing creamy yeast like colonies.
Cladosporium carrionii:
-clinical significance
-common name given to the infection
-significant microscopic appearance
-significant growth characteristics:
Causes chromoblastomycosis.
Appears as dark, long, branching conidiophores that give rise to chains of blastoconidia with septae hyphae. Cannot grow above 37oC.
-Fast growing gray black moist yeast like colony.
Fonsecaea pedrosoi:
-clinical significance
-common name given to the infection
-significant microscopic appearance
-significant growth characteristics:
-Causes chromoblastomycosis.
-Slow growing, black/brown colony with black aerial mycelium.
-Dark septate hyphae with primary mycosis conidia at conidiophore tip.
Phialophora verrucosa:
-clinical significance
-common name given to the infection
-significant microscopic appearance
-significant growth characteristics:
Causes chromoblastomycosis.
Fast growing, black/gray, dome shaped. Septate hyphae with short conidiophores that give rise to flask or cup shaped phialides with collarettes.
Sporothrix schenckii:
-clinical significance
-common name given to the infection
-significant microscopic appearance
-significant growth characteristics:
-Causes sporotrichosis.
-Rapidly growing white paste like colony that becomes brown black and leathery.
-It is a dimorphic fungus with septate hyphae and pyriform conidia arranged in floweret form.
Categories: Microbiology