Medically Significant Fungi

Flashcards on Medically Significant Fungi

Hair, Skin, Nails, Blood and Bone Marrow, Cerebrospinal fluid, Abscess Fluid, Wound exudates and Tissue, Respiratory specimen

List some common specimen types for fungal testing

Any material containing essential nutrients to support fungal growth, pH of 5.6. Add inhibitory agents to prevent bacterial contamination. Incubate 2 cultures at different temperatures to observe dimorphism.

What are the key characteristics of fungal culture media?

Brain-heart infusion agar (BHI), BHI w/ Cycloheximide & Chloramphenicol, BHI with 5 – 10% Sheep Blood, Sabouraud dextrose agar (SDA), Emmon’s modification media, SDA w/ cycloheximide and chloramphenicol (SDA-CC), Lima Bean Agar, Dermatophyte Test Medium (DTM), Mycosel or Mycobiotic agar

Name some primary culture media for medically significant fungi

Nitrate Reduction Medium and Urea Agar

What are the differential culture media mentioned in the lecture notes?

Cornmeal agar w/ Tween 80 (Chlamydospore Agar), Candida BCG Agar, BIGGY Agar, Pagano Levin Agar, CHROM Agar

Name some other differential culture media

To observe their morphological characteristics

What is the purpose of the Slide Culture / Microculture Method?

Slide Culture / Microculture Method and Hanging Drop Culture

Name two methods for observing fungal cultures

Wet mount Preparation Cellophane Tape / Scotch Tape Preparation Adhesive tape preparation & Tease mount preparation

Name some Direct Examination methods listed in the notes

NSS, 10-20% KOH, KOH w/ calcofluor white, Lactophenol Cotton Blue / LPCB, India Ink, Hucker Modification of Gram Stain

What are some common stains and reagents used in mycology?

Giemsa / Wright’s Stain ,Methenamine Silver Nitrate Stain ,Grocott-Gomori methenamine silver nitrate stain, Masson Fontana Stain, Periodic Acid Schiff / PAS ,H & E Stain

Name some other stains mentioned

Amphotericin B (AMB), Fluconazole (FLU), Itraconazole (ITRA) ,Voriconazole (VORI), Posaconazole (POSA), Caspofungin

What are the three classes of anti-fungal agents discussed?

M27-A3 : yeast testing, M38 – A2: mould testing, M44 – A: disk diffusion

What are the three methods for fungal testing?

Polyenes, Azoles, and Candins

What are the three methods for fungal agents?

Malassezia furfur, Piedraia hortae, Trichosporon beigelii complex, Hortaea werneckii

Name the four Agents of Superficial Mycoses discussed

“Spaghetti and meatballs” appearance in KOH preparation of skin scrapings, requires lipids

What are the key characteristics of Malassezia furfur laboratory diagnosis?

KOH preparation of hair shafts showing nodules consisting of asci (thick walled rhomboid cells)

What are the key characteristics of Piedraia hortae laboratory diagnosis?

Blastoconidia and arthroconidia, biochemical reactions

What are the key characteristics of Trichosporon beigelii complex laboratory diagnosis?

KOH preparation of hair shafts, blastoconidia and anneloconidia

What are the key characteristics of Hortaea werneckii laboratory diagnosis?

Epidermophyton, Microsporum, Trichophyton

What are the three Agents of Cutaneous Mycoses discussed

Dermatophytoses

Cutaneous Mycoses are the agents of

Athlete’s foot (Tinea pedis), Hair / scalp (Tinea capitis ), Jock itch (Tinea cruris), Beard (Tinea barbae), Face (Tinea faciale), Hands (Tinea manuum), Nails ( Tinea unguium), Skin (Tinea corporis, Tinea imbricata)

Name Infections caused by Agents of Cutaneous Mycoses

Thin walled , singly or in clusters, Broad and spatulate, Contains 2-5 cells

What are the Macroconidia of E. floccosum?

Sparse: clavate, sessile, Spindle shape, echinulate, 3-15 cells, tapered ends

What are the Microconidia and Macroconidia of M. canis?

Rare; with terminal chlamydospores, Chlamydoconidium-like swellings, Bizzare-shaped

What are the Microconidia and Macroconidia of M. audouinii?

Teardrop/globose Grapelike clusters, Rare: Cigar-shaped; Coiled spiral hyphae

What are the Microconidia and Macroconidia of T. mentagrophytes?

Clavate- peg- tear- shaped: Sessile, Pencil-shaped, Cylindrical

What are the Microconidia and Macroconidia of T. rubrum?

Abundant tear- club- peg- balloon- shaped, Cylindrical

What are the Microconidia and Macroconidia of T. tonsurans?

Traumatic implantation of foreign objects into the deep layers of the skin. Most commonly associated organisms are dematiaceous (darkly pigmented)

What are the general characteristics of Agents of Subcutaneous Mycoses?

Chromoblastomycosis, Eumycotic Mycetomas, Subcutaneous Phaeohyphomycosis, Sporotrichosis

Name some Subcutaneous Mycoses Diseases

Phialophora verrucosa, Cladophialophora carrionii, Fonsecaea pedrosoi, Fonsecaea compactum, Rhinocladiella aquaspersa

What species are associated with Chromoblastomycosis?

Pseudoallescheria boydii, Acremonium falciforme, Madurella mycetomatis, Madurella grisea, Exophiala jeanselmei

What species are associated with Eumycotic Mycetomas?

Lymphocutaneous, cutaneous, mucocutaneous and pulmonary

What are the clinical manifestations associated with Sporotrichosis?

Gardening, exposure to rose thorns (rose-handler’s disease) and sphagnum moss

What are the common sources of exposure to Sporotrichosis?

River valleys and basins, soil

What is the ecology of B. dermatitidis?

Bird bat guano alkaline soil

What is the ecology of H. capsulatum?

Soil

What is the ecology of C. immitis?

Blastomyces dermatitidis, Histoplasma capsulatum, Coccidioides immitis, Paracoccidioides brasiliensis, Penicilium marneffei

Name the Agents of Systemic Mycoses

Ovoid conidia borne on short coniophores, Lollipop hyphae, Large yeast, Broad-based bud

What are the key characteristics of Blastomyces dermatitidis?

Barrel-shaped arthroconidia, Spherules containing endospores

What are the key characteristics of Coccidioides immitis?

Round, large, echinulate / “knobby” tuberculate macroconidia, Small, oval yeast

What are the key characteristics of Histoplasma capsulatum?

Sterile hyphae, “Mariners’s wheel”, “Mickey Mouse cap”

What are the key characteristics of Paracoccidioides brasiliensis?

Saprophytes and Opportunistic

General Characteristics of Agents of Opportunistic Mycoses

Absidia, Mucor, Rhizopus

What are the Aseptate Zygomycetes Species of Agents of Opportunistic Mycoses

Alternaria,Cladosporium,Curvularia

What are the Septate Dematicaeous Species of Agents of Opportunistic Mycoses

Sporangiophores, smooth and ovoid internodal rhizoids

What are the characteristics of Absidia?

Sporangia remain intact, Rhizoids are absent

What are the characteristics of Mucor?

Sporangiophores clusters in a stolon, Rhizoids is at the base of sporangiophores

What are the characteristics of Rhizopus?