LP4 Mycology Flashcards
Mycology
The study of fungi
Fungi
Large and diverse over 70000 species (They are yeasts, filamentous molds, mushrooms and puff balls).
Fungi are saprophytes, parasitic, and eukaryotic organisms.
Saprophyte
feed on and decomposed dead organic material
4 Fungal Significances
1) Environmental decomposers
2) Utilize fermentation process to produce gases, alcohols and acids in beer, wine, cheese and bread
3) Provide antibiotics
4) Can be pathogenic
Mycosis
Fungal infection
4 Routes of Fungal Transmission
1) inhalation of spores
2) Introduction of fungal elements into tissue via trauma
3) Environmental exposure (i.e. homes, gyms)
4) Person to person is extremely rare
4 Phases of Fungal Growth in Yeast
1) Yeast are oval/spherical shaped fungal cell
2) Grow at 37 C
3) Reproduce by simple budding to form Blastocondia
4) Colonies are moist or mucoid
6 Phases of Fungal Growth in Molds
1) Multicellular fungus
2) Filamentous (fuzzy or velvet)
3) Reproduce by spores or conidia
4) Conidia are borne on special sporulation structures
5) Identified by morphology of spores and arrangement of hyphae
Conidium/Conidia
Spores or seeds of molds
Hypha/Hyphae
Individual filaments of molds
Mycelium/Mycelia
1) Interconnected mass of hyphae
2) Arial mycelia grow above substrate
3) Vegetative hyphae grows below substrate and absorbs nutrients (Why you should not just cut mold away on cheese.)
Septa
Cross walls found in hyphal cells of most fungi. Pores in the septa allow cytoplasm and nuclei to pass between cells.
Dimorphism
Fungi can exist as a yeast at 37 C and a mold at 25 C.
Opportunists
An organism that does not ordinarily cause disease but if conditions are right it will give rise to disease.
4 Clinical Groupings for Fungal Mycoses
1) cutaneous mycoses (hair, skin, nails)
2) subcutaneous mycoses (tissue, muscle and bone)
3) systemic mycoses (multiple organ systems)
4) opportunistic mycoses (immunocompromised)
3 Species of Medically Important Subcutaneous Fungal Infections
1) Sporothrix schenckii
2) Nocardia species
3) Actinomyces species
5 Species of Medically Important Opportunistic Fungal Infections
1) Candida species
2) Aspergillus species
3) Rhizopus species
4) Mucor species
5) Absidia species
3 Species of Medically Important Cutaneous Fungal Infections
1) Epidermophyton species
2) Trichophyton species
3) Microsporan species
4 Species of Medically Important Systemic Fungal Infections
1) Coccidioides immitis
2) Histoplasm capsulatum
3) Blastomyces dermatitidis
4) Cryptococcus neoformans
3 Keys to Fungal Identification
1) Clinical information- site of infection, appearance of lesion, travel?
2) Culture characteristics- surface texture, pigmentation
3) Microscopic evaluation of fungal elements- morphology of microconidia, macroconidia and hyphae, ID of sporulation structures
Specimens and Tools for Culturing Fungi
1) Specimens- skin, hair, sputum, cerebrospinal fluid, drainage from lesions
2) Tools- Sabouraud’s Agar (SDA)- selective for fungi, high sugar, low pH with antibiotics to prevent bacteria from growing
3) Fungal smear/stains- use microscope
a) 10% KOH- denatures protein, visible fungal agents
b) Lactophenol Blue- use tape to capture fungal elements, drop on slide of Lactophenol blue, roll tape back and examine
Conidia Fungal Elements
1) microconidia- small sac on small stalk rising above mycelium
2) macroconidia- large segmented sac on a longer stalk rising above mycelium
4 Systemic Mycoses
1) Coccidioidomycosis
2) Histoplasmosis
3) Blastomycosis
4) Cryptococcosis
Coccidioidomycosis
caused by Coccidioides immitis
