Subcutaenous mycoses Flashcards
Rapidly growing, velvety, or cottony, olive to black colony; only saprophytic Cladosporium that cannot grow above 37°C
Cladosporium carrionii
Very slow-growing, black-brown, gray-black, or olive-gray colony with black aerial mycelium; velvety to cottony texture
Fonsecaea pedrosoi
Rapidly growing, olive-gray to black, dome-shaped, woolly or cottony colony; Phialides - vase-like
Phialophora verrucosa
Rapidly growing, moist, shiny, yeasty colony that later develops black, olive, velvety mycelium; grows well at 40°C but other dematiaceous fungi do not
Wangiella dermatitidis
Longstanding lesions have a cauliflower-like surface; M. tuberculosis in Lowenstein Jensen
Chromoblastomycosis
Moderately fast-growing, gray to black, moist, yeast-like colony with black woolly mycelium; grows at 37°C but not at 40°C
Exophiala jeanselmi
Dark, long-branching conidiophores, which give rise to chains of blastoconidia; septate hyphae
Cladosporium carrionii (microscopic appearance)
Mixed sporulation: predominant form is dark, septate hyphae with primary conidia developing at conidiophore tip. Secondary and tertiary conidia also formed, branching conidiophores with chains of conidia and flask-shaped phialides
Fonsecaea pedrosoi (microscopic appearance)
Septate hyphae with short conidiophores that give rise to flask- or cup-shaped phialides; with collarettes; oval to cylindrical conidia in clusters at ends of phialides
Phialophora verrucosa (microscopic appearance)
Dark, budding yeast that later develops tube-like phialides that lack both collarettes and annellations; balls of one-celled, hyaline conidia located at openings of phialides
Wangiella dermatitidis (microscopic appearance)
Pale, brown conidiophores that form cylindrical annelids; one-celled hyaline conidia gather at tip of annelids
Exophiala jeanselmi (microscopic appearance)
Rapidly growing, cottony, white to gray colony with black reverse side; Eumycotic Mycetoma; chronic, granulomatous infection of subcutaneous and cutaneous tissues
Pseudoallescheria boydii/Scedosporium apiospermum
Sac-like cleistothecia (ascocarp) containing asci and ascospores, which are oval, pointed, and released when ascus ruptures
Pseudoallescheria boydii/Scedosporium apiospermum (teleomorph)
Golden-brown, elliptoid, single-celled conidia on tips of conidiophores
Pseudoallescheria boydii/Scedosporium apiospermum (anamorph)
Rapidly growing, white, pasty, moist colony that later becomes brown, black, wrinkled, or leathery; Sporotrichosis (Rose gardener’s disease)
Sporothrix schenckii
Dimorphic fungus; Mycelial form (25°C): narrow, septate hyphae with pyriform conidia arranged singly or in floweret/rosette arrangement; Yeast form (35°C–37°C): small, elliptoid budding, cigar-shaped yeast
Sporothrix schenckii (microscopic)
Microscopy: Asteroid bodies - basophilic yeast surrounded by eosinophilic material due to Ag-Ab reactions
Sporothrix schenckii
Rhinosporidiosis; lymphoid masses in nose and pharynx; Tissue Microscopy
Rhinosporidium (Aquaspersa) seeberi
Lobomycosis; Keloid-like subcutaneous nodule in extremities; Tissue Microscopy (multiple cells in chain)
Loboa loboi / Lacazia loboi
White soft granules
Acremonium, Curvularia, Fusarium (banana/sickle/crescent-shaped macroconidia), Pseudallescheria, Scedosporium
Black, soft granules
Exophiala spp.; Trematosphaeri grisea (old name Modurella grisea)
Black, hard granules; no. 1 cause of eumycotic mycetoma
Aspergillus, Modurella mycetomatis
Other names: North American Blastomycosis, Chicago disease, Gilchrist’s disease
Blastomycosis
Blastomyces dermatitidis antigens
Antigens (A and B)
On Sabouraud dextrose agar (SDA), colony first white, waxy, yeast-like and later cottony with white aerial mycelium; turns tan to brown with age
Blastomyces dermatitidis (Mold phase)
On brain-heart infusion (BHI) agar with blood, colony cream to tan, waxy, and heaped or wrinkled; inhibited by chloramphenicol or cycloheximide
Blastomyces dermatitidis (Yeast phase)
Delicate, septate hyphae with round or pyriform conidia, seen as “lollipops” or pyriform conidia
Blastomyces dermatitidis (Microscopy)
Thick-walled, large Broad-based, budding yeast; broad isthmus at constriction
Blastomyces dermatitidis (Yeast form)
Blastomyces dermatitidis (Tests)
Blastomycin skin test; Exoantigen test
Coccidioides immitis: Other names: San Joaquin Valley fever, Desert fever
Coccidioides immitis antigens
Antigens: HS, HL, F
Moist, gray membranous colony that develops white, cottony aerial mycelium (“cob-web colony”); turns tan to brown with age
Coccidioides immitis (Colony)
Coarse, septate, branched hyphae that produce thick-walled, rectangular arthroconidia, that alternate with empty disjunctor cells
Coccidioides immitis (Hyphae)
Large, round, thick-walled spherules with endospores observed in tissue and direct examination; not a true yeast
Coccidioides immitis (Spherules)
Major biohazard (Laboratory-acquired infection); Spherulin antigen test; Coccidioidin skin test
Coccidioides immitis (Tests)
Histoplasmosis / Darling’s disease, Spelunker’s disease / Cave disease
Inhalation of droppings from bat, bird guanos, chicken coops
Antigens are quite similar to B. dermatitidis antigens; may yield false positive
Histoplasma capsulatum
On SDA, white to brown or pink mold with fine, dense, fluffy texture; white, yellow, or tan reverse side
Histoplasma capsulatum (Mold phase)
On BHI, moist, white to cream, heaped colony; may be inhibited by cycloheximide or chloramphenicol
Histoplasma capsulatum (Yeast phase)
Histoplasma capsulatum (Microscopy - Mold form)
Septate hyphae with round to pyriform microconidia on short branches or directly on hyphal stalk; later, large, round, thick-walled knobby tuberculate forms
EDTA Blood smear - Small, budding, round to oval yeast cells; intracellular to mononuclear cells with Giemsa or Wright’s stain; Microscopy: yeast cells in Wright/Giemsa stain inside monocytes or macrophages
Histoplasma capsulatum (Microscopy - Yeast form)
Histoplasma capsulatum (Tests)
Histoplasmin skin test
Paracoccidioides brasiliensis
Antigens – 1,2,3
Other names: Brazilian Blastomycosis, Lutz-Splendore-Almeida disease
Paracoccidioidomycosis
On SDA, white, glabrous, leathery colony; turns tan-brown with age; short aerial mycelium
Paracoccidioides brasiliensis (Colony - Mold Phase)
On blood agar, cream to tan, moist, wrinkled colony; turns waxy with age
Paracoccidioides brasiliensis (Colony - Yeast Phase)
Small, septate, branched hyphae with intercalary and terminal chlamydoconidia; few pyriform microconidia
Paracoccidioides brasiliensis (Microscopy - Mold Phase)
Large, round to oval, thick-walled yeast cells with multiple buds that attach to mother cell by narrow constrictions; resembles a ‘ship’s wheel’
Paracoccidioides brasiliensis (Microscopy - Yeast Phase)
Paracoccidioides brasiliensis (Tests)
Microscopy (Multipolar budding/mariner’s house/wheel/Mickey Mouse head yeast cell); Exoantigen test; Serology
Aspergillus species
Widespread in nature; Aspergillosis
External otomycosis, Mycotic keratitis, Onychomycosis, Fungus ball (chest X-ray)
Aspergillus species
Aflatoxin - food poisoning (e.g., peanut butter)
Aspergillus species (Toxin)
Most frequently isolated; causes pulmonary, eye, CNS, and systemic infections
Aspergillus fumigatus
Rapid growth within 2 days
Fluffy, granular, or powdery texture; pigment depends on species; Aspergillus species
Aspergillus that is white to blue-green
A. fumigatus
Aspergillus that is black
A. niger
Aspergillus that is yellow to green
A. flavus
Aspergillus that is tan to cinnamon
A. terreus
Branching, septate hyphae that terminate in a conidiophore, which expands into a large, spherical vesicle. Vesicle is covered with sterigmata (stalks) and parallel chains of conidia cover the sterigmata
Aspergillus species (Microscopy)
Aspergillus species (Specimen/Tests)
Specimen: Sputum, Aspirate; Microscopy, MRI/CT, X-ray
Widespread in nature; causes Rhinocerebral mucormycosis, vascular invasion, thrombosis, and necrosis
Zygomycetes
Coarse, woolly, fluffy, white to gray or brown mycelium with black or brown sporangium. Hyphae grow within 1–3 days and rapidly cover agar surface
Zygomycetes (Colony)
Large, broad, nonseptate hyphae that produce horizontal runners (stolons) attaching at contact points via rootlike structures (rhizoids); sporangiophores arise in clusters at rhizoids and terminate in sporangia
Rhizopus
Similar to Rhizopus; sporangiophores arise between nodes from which rhizoids are formed
Absidia
No rhizoids - no rootlike structure
Mucor
Zygomycetes (Specimen/Tests)
Common laboratory contaminant; Specimen: Tissue Aspirate; Microscopy
Dimorphic fungi
Includes Blastomyces, Histoplasma, Coccidioides, Paracoccidioides, Sporothrix, Penicillium/Talaromyces, Emmonsia
Inhalation of adiaspores leads to Adiaspiromycosis; cutaneous infection
Emmonsia spp
