Transcript FUNGI
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 30ºC – mycelial form with small, truncate aleurioconidida Growth rate: slow to moderate (up to 7 days) 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 Arthroconidia are thick-walled, barrelshaped, and 2-4 x 3-6 µm in size. Typically, these arthroconidia alternate with empty disjunctor cells. Rapidly – growing colony Histoplasma capsulatum • 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 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. Slow – growing colony