Mycology Disease of Yeast & Mold

Mycology Study of fungi includes yeast and mold Eukaryotic cell Chemo-heterotroph - require organic compounds for energy and carbon source Most have cell wall of chitin

Mold Septate hyphae - cross wall divide hyphae into uninucleate unit Hyphae - long filament Septate hyphae - cross wall divide hyphae into uninucleate unit Non-septate (coenocytic) hyphae - no cross wall Mycelium – hyphae grow, intertwine

Yeast Non-filamentous, unicellular fungi Oval or spherical in shape Reproduce by budding Pseudohyphae - buds fail to detach; i.e. germ tube test for Candidia

Dimorphic Fungi Dimorphism – two forms of growth, either yeast or mold; most pathogens Temperature dependent: 37°C grows as yeast RT grows as mold CO2 concentration or presence of serum may also be a determining factor Dimorphism of Candida different: 37°C grows as mold in serum (Germ tube test) RT grows as yeast

Lab ID Type of hyphae: septate, non-septate Color of mycelium Reproductive structures: Sexual spores - fusion of nuclei from two opposite mating strains of same species; only under special conditions Asexual spores - commonly used in ID; aerial mycelium by mitosis and cell division Results in conidia

Arthrospores Arthron = “joint”, arthroconidia Fragmentation of septate hyphae i.e. Coccidiodes

Chlamydospores Chlamy = “mantle” Thick walled spores formed within a hyphae i.e. Candida

Sporangiospores Angeion = “vessel” Sporangium - Spores formed within a sac i.e. Rhizopus

Condiospores Conidia = “dust’ Conidiophore –aerial mycelium; spores produced at end Macroconidia -multicelled conidiospores i.e. Histoplasma

Blastospores Blastos = “bud” “shoot”, Blastoconidia Bud coming off parental cell i.e. Blastomyces

Fungal Diseases Mycosis - fungal infection Mode of entry & infective tissue: Superficial Cutaneous Subcutaneous Systemic Opportunistic

Superficial Mycoses Localized hair shaft, surface epidermis Direct contact with infected hair, skin White piedra - white balls found on hair shafts;Trichosporon Black piedra - infecting hair, producing hard, dark nodules; Piedraia

Cutaneous Mycoses “Ringworm” – hair, epidermis, nail Epidermophyton, Microsporum, Trichophyton Dermatophytes - secrete keratinase Person to person, animal to person Direct contact infected hair, skin Tinea capitis (scalp, hair), Tinea pedis (athlete’s foot), Tinea unguium (nails)

Subcutaneous Mycoses Mycetoma - beneath skin Fonsecaea, Phialophora, Pseudoallescheria Fungi that live in soil and vegetation Spores or hyphae planted directly into puncture wound Infection not contagious

Systemic Mycosis Deep, involve tissues and organs Saprophytic fungi, live in soil Inhalation of spores - in lung, spreads other tissues Often resemble tuberculosis Not contagious Blastomycosis - Blastomyces, flu-like, pulmonary Coccidioidomycosis - Coccidiodes, San Joaquin Valley Fever Histoplasmosis - Histoplasma, pulmonary

Opportunistic Mycoses Harmless in normal habitat (includes normal flora), pathogenic in debilitated host Mucormycosis – Mucor; diabetic patient with ketoacidosis Aspergillosis – Aspergillus; inhale spores, neutropenic patient (lung disease, cancer) Candidiasis – Candida Vulvovaginal following antibiotic therapy Thrush of mouth and throat

MICR 301 Final Exam (200 pts.) Tuesday, Dec. 6, 2011 8:00 – 10:30am Lecture, Reading, Key Terms, Learning Assessment Questions, Five Case Study Virus, Bacteria, Fungi, Parasite Lectures Part I (~65%): Mechanism of Pathogenesis thru Parasites Part II (~35%): Introduction thru Specific Host Defense Objective (M.C., Terms, T/F), Short Essay