Subcutaneous Mycoses Flashcards
Chromoblastomycosis
Chronic fungal infection acquired via traumatic inoculation of slow-growing dematiaceous fungi
Primarily located in lower extremities
Principle Agents of Chromoblastomycosis
Fonsecaea pedrosi
Fonsecaea compacta
Phialophora verrucosum
Cladophialophora carrionii
Chromoblastomycosis Characterized Infection
Development of papule at site of trauma
Slowly spreads to form warty or tumor-like lesions
“cauliflower-like”
Types of sporulation
Phialophora
Rhinocladiella
Cladosporium
Phialophora type sporulation
Conidiophores are vase or flask-shaped
Rhinocladiella-type Sporulation
Conidiophores are swollen, knotted, or club-shaped
Terminally or laterally on hyphae
Bearing elongated conidia along upper portion and tips
Cladosporium-type Sporulation
Conidiophores vary in length, treelike branching
Bearing ovoid conidia branching chain
Hila spots seen
Sclerotic bodies
Muriform cells
Thick cross walls
Mature cells have intersecting cross walls
Younger stages - no septa
Fonsecaea pedrosi General Info
Resistant to most anti-fungal agents
Slow growing (2-3 wks)
Fonsecaea pedrosi Colony Morph
Brown to black, delicate velvety mycelium
Reverse: Black
Convex, cone-shaped protrusion
Slightly embeds agar
Fonsecaea pedrosi Microscopic Morph
Septate hyphae
Conidia arise from short denticles with sympodically
Primary conidia appear as rhinocladiella-type
Sclerotic bodies seen
Fonsecaea compacta General Information
Slow growing (28 days)
Fonsecaea compacta Morphology
Same as F. pedrosi
Fonsecaea compacta Microscopic
Hyphae are branched
Predominately cladosporium-type sporulation seen
Sclerotic bodies seen
Phialophora verrucosum General Info
Second most common cause of chromoblastomycosis
Slow growing (14 days)
Phialophora verrucosum Colony Morphology
Olive green to brown to black
May be heaped and granular
Embeds in medium
Reverse: Black
Phialophora verrucosum Microscopic
Hyphae are septate and branched
Phialophora-type sporulation, vase-shaped conidiophores either lateral or terminal
Sclerotic bodies seen
Other Names for Sclerotic Bodies
Muriform cells
Copper pennies
Meddler bodies
Mycetoma definition
Localized, chronic, granulomatous infection involving cutaneous and subcutaneous tissues
Usually found on feet or hands but may be on other parts of the body
Organisms that cause Mycetoma
Actinomyces
Nocardia
Streptomyces
Development of Mycetomas
Traumatic injury by contaminated:
Thorns
Splinters from plants
Fish scales or fins
Snake bites
Insect Bites
Farm Implements
Knives
Sharp objects used by field workers
Mycetomas Location
Primarily in tropical and hot temperate zones
- Africa, Asia, South and Central America
Mycetoma lesions
Contain granulomas and abscesses that suppurate and drain through sinus tracts
Causative Agents of Eumycotic Mycetomas
Exophiala jeanselmei
Pseudallescheria boydii/Scedosporium apiospermum
Madurella mycetomatis
Exophiala jeanselmei General Info
India, Malaya, Thailand, Argentina, and United States
Infections secondary to trauma involving contaminated wood products
Growth rate - 2 weeks
Exophiala jeanselmei Colony Morphology
Yeast like and green to black
At 2 wks, grey to olive grey aerial mycelium
Reverse: Black
Exophiala jeanselmei Microscopic
Septate, branched hyphae
Conidiophores may be branched with tapered ends borne at obtuse or right angles from hyphae
Elliptical conidia aggregate in clusters at tips and sides of conidiophores
Exophilia jeanselmei other testing
Tyrosine - decomposes
Casein - negative
Xanthine - negative
KNO3 assimilation - positive
Pseudallescheria boydii (sexual state)
Scedosporium apiospermum (asexual state)
General info
Growth rate 7 days
P. boydii/S. apiospermum Colony Morphology
Floccose and white at first
Grey to dark brown with age
Reverse: white at first, then grey or black with age
P. boydii/S. apiospermum Microscope
Septate hypha with simply long or short conidiophores bearing conidia singly or in small groups
Asexual stage of P. boydii/S. apiospermum
Conidia are unicellular, oval with larger end toward apex
Truncated (cut off) appearance at base
Sexual stage of P. boydii/S. apiospermum
Large cleistothecia typically round
Asci and Ascopores are formed and held until bursting
P. boydii/S. apiospermum additional testing
Produce white to yellowish white granules in tissue sections
Soft to firm
Composed of hyaline hyphae
Madurella mycetomatis General Info
Location: Western and Eastern Africa
Growth rate - 10 days
Better growth at 37 C
Madurella mycetomatis Colony Morphology
Varies greatly
White then becoming olive, yellow, brown
Flat or domed shape
Velvety to glabrous
Characteristic brown diffusible pigment
Madurella mycetomatis Microscopic
SAB: septate hyphae with chlamydoconidia-like cells
CM: produce conidiophores (phialide type), round or oval conidia
Madurella mycetomatis Other tests
Reddish brown to black granules in tissue sections
Firm to hard
Compact
Variable in size and shape
Frequently multilobulated
Phaeohyphomycosis definition
Describes ANY subcutaneous infection caused by any number of dematiaceous organisms exclusive of chromoblastomycosis or mycetoma
Exophiala dermatitidis General Info
Slow growth rate
Yeast like at 10 days
Mold like within 21 days
Exophiala dermatitidis Colony morphology
Yeast like at first. Develop aerial mycelium with age. Olive to black color
Reverse: dark
Exophialia dermatitidis Microscope
Young cultures: oval to round, budding yeast like cells
Mature cultures: Septate hyphae and flask-shaped to cylindric phialides that lack a flared lip
Exophialia dermititidis Other tests
Tyrosine - decomposes
Casein - negative
Xanthine - negative
Growth at 42 C
KNO3 assimiliation - negative
Sporotrichosis
Chronic infection characterized by lymppocutaneous lesions of the cutaneous and subcutaneous tissues that suppurate, ulcerate, and drain
Sporotrichosis organisms
Sporothrix schenckii
Sporothrix schenckii General Info
Rapid growth - 4 days
Sporothrix schenckii Colony Morphology
25-30 C - first moist and yeast like, later becomes wrinkled, leathery or velvety and brown to black
35-37 C - cream or tan, smooth and yeast like
Sporothrix schenckii Microscopic
25-30 C septate hyphae with slender erect tapering conidiophores at right angles to hyphae. Pear-shaped conidia with dentricles - “rosette” or “daisy-head” conidia
35-37 C oval to round, fusiform budding yeast “cigar bodies” on BHI
