Glossary of ID 6.1

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Kingdom Fungi: groups
Yeasts, moulds, rusts & mushrooms
Kingdom Fungi: General Properties
Cells w/cell wall composed of CHITIN
2 basic forms of fungi
Yeasts and moulds
Small, singular oval cells
Exhibit budding
Yeasts: budding
Two results
Form of budding (yeasts)
Complete separation of daughter from parent cell
Incomple separation (from budding) found in some yeast
Filamentous strands (hyphae)
Septate or non-septate
Mass of hyphae
Aerial hyphae
Support reproductive structures of moulds, including sexual spores or asexual conidia
Sporophyte (diploid) undergoes meiosis to form a SPORE. The spore undergoes mitosis to form a gametophyte. The gametophyte produces a gamete, which will then fuse to form the zygote, which grows to become the sporophyte and the cycle is completed.
Asexual (mitotic) reproduction of moulds. Like a spore, but not formed by sexual (meiotic) reproduction.
Dimorphic fungi
Grow as yeasts (in vivo) and moulds (in vitro)
Fungal Cell Wall
Key elements: glucan, chitin, ergosterol (chief component of plasma membrane)
Key component of fungal cell membrane. Signigicance? Synthesis parallels our own cholesterol synthesis. Therefore, drugs that target ergosterol biogenesis may be toxic to host
Common sites of fungal infections
Exposed surfaces, including lungs, skin and mucous membranes
Dermatophytes: mycology
3 common genera: Microsporum; Trichophyton; Epidermophyton
Dermatophytes: general
Caused by 3 common genera
Involve feet, nails, body, hair or groin
Tinea pedis
"Athletes' Food"
Caused by dermatophytes
Esp. between 3rd, 4th and 5th toes (lack sweat glands?)
Nail Infection
UNDER THE NAIL. Topical anti-fungal medications will NOT work. Need systemic treatment. May be proximal (immunocompromised) or distal (most common) infections
Tinea cruris
Jock Itch
Caused by dermatophytes
Tinea corporis
Caused by dermatophytes
Tinea capitas
Hair shaft involvement
Ecto vs. endothrix (w/in or outside hair shaft)
Dermatophyte infection
Dermatophyte infection: diagnosis (esp., significance of KOH?)
KOH dissolves host cells and enables you to visualize hyphae)
Filamentous Fungi
Aspergillus: general
Filamentous fungus
Ubiquitous in environment, disease follows inhalation of conidia
Aspergillus: structure
Cotton colonies
Septate, acute-angled hyphae
Aspergillus and tendency to cause disease
Generally, colonization (of low virulenece)
Will be a problem in the immunocompromized host and may lead to invasion
Aspergillus: initial exposure
Hypersensitive pneumonia (bulk load, i.e. shoveling mouldy hay); colonization; no colonization
Aspergillus: following colonization
No sequellae; aspergilloma; allergic bronchopulmonary aspergillosis; invasion
Following colonization
"Fungus Ball"
Occurs in patients w/some other preexisting disease (i.e. TB) that creates cavities
On X-ray, see round oval mass w/stalk w/in a cavity
Allergic Bronchopulmonary Aspergillosis (ABPA)
Following colonization
Occurs in patients w/preexisting astham, marked by elevated eosinophils, IgE, and fleeting pulmonary infiltrates
Invasive pulmonary aspergillosis
Of immunocompromized
May be acute (profound immunodeficiency) or chronic (generally poor health, i.e. diabetes)
Acute Invasive Pulmonary Aspergillosis
Invasion following colonization in the severely immunodeficient. Necrotizing, disseminating and w/high morbidity (if WBCs cannot be elevated/improved)
Aspergillosis: miscellaneous infections
Ear, sinuses, endocarditis and cutaneous infections
Aspergillosis: diagnosis
Demonstration w/in tissue + culture
Recently, ELISA targeting galactomannan and B-glucan
AKA Mucormycosis (Zygomycosis)
Ubiquitous and low virulence
Mucorales: pathogenesis
Respiratory infection
Generally affects immunodeficient (like Aspergillus)
May lead to rhinocerebral mucormycosis or pulmonary mucormycosis
Diagnosis: mucorales vs. aspergillus?
Mucorales: broader, aseptate, right-angle branches
Aspergillus: finer, septate, acute-angle branches
New, oral medication for mucorales infection
Filamentous fungi: penicillium marneffei
Southeast Asia
AIDS patients
Skin lesions (w/dimples)
Similar clinical presentation as histoplasmosis
Additional filamentous fungi
Dematiaceous fungi (dark-walled fungi) and Scedosporium apiospermum

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