Mycology mid-term

How does Sepedonium sp differ from Histoplasma capsulatum?

1. does not form microconidium 2. will not convert to a yeast at 35-37 3. is H. capsulatum DNA probe negative

Invasive infection

A. fumigatus, A. terreus, or A. niger

Sexual state: Eurotium herbariorum

Aspergillus glaucus

Sexual state: Emericella nidulans

Aspergillus nidulans

Look alikes to dimorphic fungi:

Beauveria Chrysosporium Sepedonium

Resembles the dimorphic fungi sporothrix schenckii

Beauveria sp

Forms of Aspergillosis disease in order (1-5)

Colonization Allergy (farmer's lung) Fungus ball Toxicoses Invasive infection

Colony morphology: 25-30: flat, tan, becomes reddish yellow; deep red pigment diffuses into medium after 3-7 days; reverse is brownish red 35-37: soft, white to tan, dry and yeast-like; conversion may take up to 14 days

Penicillium marneffei

Look alikes producing conidia in chains:

Penicillium sp Paecilomyces Scopulariopsis

Microscopic: Septate hyphae, branched or unbranched conidiophores with secondary branches called metulae; flask-shaped phialides bearing unbranched chains of conidia. Resembles a paintbrush or "skeleton hand".

Penicillium spp

What species forms no vesicle?

Penicillium spp

Microscopic: 35-37: round or oval yeast-like cells (3-8 um) having central cross walls. Cells multiply by fission rather than budding

Pennicillium marneffei

Colonization

no disease manifestation

Different genera of zygomycetes are differentiated according to:

presence or absence of rhizoids, branched or unbranched sporangiophores, presence or absence of and apophysis, shape of columellae, sporangia, and temperature tolerance

Fungus ball

A. fumigatus or A. niger

Oblong conidia or longer conidia:

Acremonium Fusarium

Common contaminate; etiologic agent of mycetomas, corneal infections, and nail infections, rare cause of invasive disease Microscopic: Septate hyphae; erect, unbranched, tapering phial ides bearing oblong conidia which are usually one-celled but can be two-celled; the condo form easily disrupted clusters at the tips of phialides

Acremonium spp

Other zygomycetes include

Apophysomyces sp Cunninghamella sp Syncephalastrum sp

Second most common cause of invasive aspergillosis; produces aflatoxins Microscopic: Uniseriate and biseriate phialides form over most of the vesicle; long, rough, spiny conidiophores

Aspergillus flavus

Most common cause of disseminated aspergillosis, allergic aspergillosis, and fungal sunusitis Microscopic: Uniseriate, phialides on upper 2/3 of vesicle only, columnar formation Thermotolerant (grows at 45-48)

Aspergillus fumigatus

Reported infections of nails, ear, brain, and cardiovascular and visceral sites Microscopic: Uniseriate, phialides loosely cover entire vesicle, cleistothecia produced

Aspergillus glaucus

Reported infections in a variety of sites; causes more lethal infections in patients with chronic granulomatous disease Microscopic: Biseriate; cleistothecia produce red ascospores upon extended incubation; cleistothecia surrounded by numerous round hulle cells

Aspergillus nidulans

Common cause of otomycosis and fungus ball and may cause disseminated disease. Microscopic: Biseriate, long conidiophores, phialides cover entire vesicle, black/brown conidia, hyaline hyphae

Aspergillus niger

Direct specimen exam: Dichotomous branching hyphae (45 degree angle branching resembling letter Y)

Aspergillus spp

Microscopic: Septate hyphae (3-8 um), foot cells, conidiophores swollen to form vesicles with uniseriate or biseriate phialides, conidia in chains

Aspergillus spp

Allergy (farmer's lung)

Aspergillus spp or Penicillium spp

An agent of allergic bronchopulmonary aspergillosis; may disseminate Colony morphology: Tan to cinnamon (with sugar) brown Microscopic: Biseriate; hyaline cells (solitary conidia) produced directly on hyphae; thin, compact phialides producing small conidia

Aspergillus terreus

Common contaminate; very rarely involved in human infections Microscopic: Sepate hyphae, delicate and narrow. Conidia producing structures exhibit zigzag terminal extensions (sympodial geniculate growth). Conidia are small, round oval, and form singly on denticles.

Beauveria sp

Common contaminate; rarely assoc with nail infections Micrscopic: septate hyphae; one celled, clavate condia with a rounded apex and broad flattened base; conidia often carry a remnant of the hyphal wall after detachment from the hyphae; conidia may form directly on hyphae or at the ends of simple or branched conidiophores

Chrysosporium spp

Young colonies can resemble Blastomyces dermatitidis

Chrysosporium spp

Common fungi inhibited by cycloheximide

Cryptococcus neoformans Candida parapsilosis Candida krusei Candida tropicalis Trichosporon spp Aspergillus spp Pseudallescheria boydii complex (scedosporium apiospermum) Scopulariopsis spp Common zygomycetes

Aspergillus morphology is seen on what media?

Czapek-Dox agar

Contaminate, but can cause eye infections. Has also been reported in individuals following consumption of grain which has become overgrown with toxin producing strains Microscopic: Septate hyphae; two types of sporulation: 1) sickle or canoe-shaped macroconidia with multiple septations, produced from phialides on unbranched or branched conidiophores and 2) long or short conidiophores bearing small, oval conidia (microconidia) that are either one or two celled, and are arranged singly or in clusters

Fusarium spp

Common contaminate Microscopic: Similar to penicillium but, conidia clump together to form large clusters or balls

Gliocladium

Producing conidia in balls/clusters:

Gliocladium Trichoderma Verticillium

Usually a contaminate, but can be associated with keratitis, endocarditis, sinusitis, nephritis, cutaneous and subcutaneous infections, pulmonary infections, and fungemia Microscopic: Similar to penicillium spp. but phial ides are elongated and taper to a long slender tube and bend away from the axis of the conidiophore. Conidia are elliptical or oblong

Paecilomyces spp

Causes infection in immunocompromised and immunocompetent individuals; Endemic to areas of southeast asia; seen with increasing frequency in AIDS patients who have traveled to this area. Thermally dimorphic

Penicillium marneffei

Cause mucormycosis (zygomycosis)

Rhizopus spp Rhizomucor spp mucor spp Lichtheimia sp (Absidia sp)

Zygomycetes most common etiologic agents:

Rhizopus spp Rhizomucor spp mucor spp Lichtheimia sp (Absidia sp)

Common contaminates but can infect the nails (especially toenails). Sometimes causes infection of soft tissue, bone, and lungs in the immunocompromised Microscopic: Short conidiophores and annelides bearing conidia with larger (4-9 um), thick-walled, lemon shaped and cut off at the base (truncate). Mature conidia are usually rough and spiny.

Scopulariopsis spp

Common contaminate Colony morphology: 25: at first white and waxy, then becomes fluffy and may turn yellow 37: little or no growth Microscopic: Septate hyphae; conidiophores are simple or branched and bear large conidia which are usually rough and knobby; resembles Histoplasma capsulatum

Sepedonium sp

Aspergillus sp morphology on Czapek-Dox agar:

Surface: may be yellow, green, blue, orange, gray, brown, or black Reverse: white to goldish or brown with radial grooves

Common contaminate; rarely assoc. with infections in immunocompromised Microscopic: septate hyphae, short conidiophores often branched at wide angles, flask shaped phialides forming at wide angle to the conidiophore. Round conidia clustered at the end of each phialide.

Trichoderma

Common contaminant; rarely etiologic agent of keratitis Microscopic: Septate hyphae, simple or branched conidiophores in whorls; elongated phialides, each having a pointed apex; oval, single-celled conidia occurring singly or in clusters at the ends of the phialides

Verticillium sp

Microscopic: Wide (broad), non-septate or sparsely septate hyphae (6-15 um), ribbon like, often fragmented, extremely long sporangiophores bearing sporangia

Zygomycetes

Toxicoses

aflatoxin due to A. flavus

________ Reproduction occurs within a sporangium (internal contents are cleaved into spores)

asexual

Also know as the "lid lifters"

zygomycetes

Grinding of tissue may render ____________ non-viable (unable to be cultured)

zygomycetes

Diabetic patients are predisposed to

zygomycosis