MycologyMycologyMycologyMycology

Disease of Yeast & MoldDisease 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 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 301Final 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