LAB 12: THE FUNGI

FUNGI: FRIEND OR FOE? Both! There are fungal pathogens and beneficial fungi Eat them Help us make bread, cheese, alcoholic beverages Vast majority of antibiotics are made by fungi

FUNGI: FOE Cause infections – superficial – to – systemic Allergies – over 37 million people suffer from allergies that are believed related to fungi (Penicillium and Aspergillus spp.) –Sick Building Syndrome (Stachybotrys sp.) Contaminate our water – breathing problems, watery eyes

FUNGI - Fungi are eukaryotic ; exist as unicellular or multi-cellular organisms -Microscopically they are larger than bacteria, with more complex cellular morphology and detail -Two types of fungi: Yeast and Moulds

FUNGI: YEAST - Yeasts are non-filamentous, unicellular fungi that are typically spherical or oval in shape. -Colonial morphology is similar to bacteria. -They reproduce by budding.

FUNGI: YEAST Candida albicans – most common yeast isolated from human samples

FUNGI: YEAST

FUNGI: MOULDS -Moulds are multicellular filamentous fung.

DERMATOPHYTES

Dermatophytes cause infections of the skin (athletes foot), hair, and nails Utilize the protein keratin in the epidermis Invasion elicits a host response ranging from mild to severe RINGWORM – Tinea corporis

Trichophyton rubrum White, granular or fluffy strains Reverse is deep red or purplish

Trichophyton rubrum

ZYGOMYCETES

AGENTS OF MUCOMYCOSIS INFECTIONS Allergic Cutaneous Rhino cerebral Pulmonary GI Disseminated

AGENTS OF MUCOMYCOSIS RISK FACTORS Ketoacidosis Neutropenia (macrophages kill spores; neutrophils kill germinating hyphae) Iron overload Iron chelation drug use IDU Immunosuppression Emerging – LTT with voriconazole in HSCT/HM

AGENTS OF MUCOMYCOSIS ACQUIRE Inhalation Traumatic implantation Ingestion TREATMENT Frequently unsuccessful Liposomal AMB with POZA Debridement Correct underlying condition

DIRECT EXAMINATION

RAIDLY-GROWING – ‘LID LIFTERS’

STRUCTURES CAN BE ASEXUAL OR SEXUAL

HYPHOMYCETES

Aspergillus fumigatus Rapidly – growing, white, turning green

Aspergillus fumigatus Short phialphores bearing uniserate phialides covering 2/3 of a flask-shaped vesicle

Pencillium species Rapid growth, white becoming green

Pencillium species Branched or unbranched flask-shaped phialophores on metulae, smooth or rough ROUND conidia, “Penicillus” or “Brush” appearance

DIMORPHIC FUNGI

Blastomyces dermatitidis Blastomycosis Southeast / South-Central U.S. that border Mississippi / Ohio River valleys Midwest/Southern Canadian provinces bordering the Great Lakes (****Wisconsin) Soil (esp. around rotting wood)

Blastomyces dermatitidis Sites of Infection Pulmonary (asymptomatic, acute, chronic)  disseminated (bone, skin, prostate) Cutaneous Bone/Joint GU CNS

Blastomyces dermatitidis Direct Examination 37ºC – large (8 x 30 µm) broad-based budding yeast forms )

Blastomyces dermatitidis Growth rate: slow to moderate (up to 7 days) 30ºC – mycelial form with small, truncate aleurioconidida

Coccidioides immitis Complex Coccidioidomycosis C. immitis – CA, San Joaquin Valley C. posadasii – Southwest U.S. (TX, AZ), Central / South America Both – Desert Southwest and Mexico Soil, excavation

Coccidioides immitis Complex Sites of Infection Pulmonary**** - acute and chronic Skin Bone or joint CNS

Coccidioides immitis Complex Direct Examination 37C – large spherule (15–75 µm) containing endospores

Coccidioides immitis Complex Rapidly – growing colony Arthroconidia are thick-walled, barrel- shaped, and 2-4 x 3-6 µm in size. Typically, these arthroconidia alternate with empty disjunctor cells.

Histoplasmosis U.S. – Tennessee/Ohio / Mississippi River valleys, Central America, Asia Africa and Caribbean Soil, birds and bats Histoplasma capsulatum

Sites of Infection Pulmonary**** - symptomatic to fulminate Disseminated GI or CNS Pericarditis Ocular [ Presumed ocular histoplasmosis syndrome (POHS)] Histoplasma capsulatum

Direct Examination 37C – small budding yeast Histoplasma capsulatum

Slow – growing colony Macroconidia are tuberculate, thick-walled, round, unicellular, hyaline, large and often have fingerlike projections on the surface. These macroconidia are also referred to as tuberculochlamydospores or macroaleurioconidia.