Exam 1 - Mycology Flashcards
Characteristics of Fungi
- Eukaryotic
- Sterols
- Chemoheterotrophs
- Aerobes
- Saprophytic
- Acquire food by absorption
- Produce sexual and asexual spores
Saprophytic
Living on dead or decayed organic matter
Molds
Multicellular, fliamentous form of fungi consisting of thread-like filaments to form fuzzy colonies
TEMP -
Yeast
Unicellular; produce circular, restricted, pasty or mucous colonies
- sexual or asexual reproduction
TEMP -
Asexual reproduction of yeast
Budding, binary fission
Dimorphic
Exhibit either a yeast or mold phase; may be temperature dependent
Hyphae
Microscopic filaments that can branch and form a network
Septate (Hyphae)
Frequent perpendicular cross walls
Sparsely septate (Hyphae)
Infrequent perpendicular cross walls
Aseptate (Hyphae)
No septation (older term) Sparsely septate is correct
Hyaline (Hyphae)
Nonpigmented hyphae
Dematiaceous (Hyphae)
Dark and pigmented hyphae
- due to presence of melanin in the cell wall
Mycelium
A network of hyphae (colony)
- extends over or through whatever substrate the fungus is using as a source of food
Conidia
Fungal spores
role of Conidia
- means of dispersal
- means of survival (low metabolic state, dormant state)
Superficial (spectrum of disease)
Confined to the outermost “dead” layer of the skin or hair
Cutaneous (spectrum of disease)
Affects the keratinized layer of the skin, hair, or nails
Mucosal (spectrum of disease)
Typically local infection
Systemic (spectrum of disease)
Highly invasive infection
- affects the internal organs or deep tissues of the body
Opportunistic (spectrum of disease)
Found primarily in immunocompromised persons; infections of a great variety of tissues
Innate Resistance
Natural resistance of an immune system, can keep spores/fungi populations under control
(Healthy immunocompetent individuals - high innate resistance to fungal infections)
Diagnostic challenge of opportunistic mycoses
An immunocompromised person at risk for fungal infections
- creates a complexity of the patient population at risk
- increasing array of fungi that can infect these individuals
Superficial/cutaneous (Mode of Transmission)
Person to person or form animal to human contact
Subcutaneous (Mode of Transmission)
Through the skin (trauma to the skin)
Deep mycoses (Mode of Transmission)
Opportunistic growth in immunocompromised; inhalation of spores; or presence of intravenous devices
Lab values to support Bacterial pathogen
↑ WBC, Neutrophils, ↑ total protein, ↓glucose, CSF Lactate > 35 mg/dl
Lab Values to support Viral Pathogen
↑ WBC, Lymphocytes, ↑ total protein (moderate), normal glucose, Normal lactate
Lab Values to support Fungal Pathogen
↑ WBC, Lymphocytes and monocytes, ↑ total protein (moderate), normal to low glucose, lactate > 25 mg/dl
Specimen Collection (general)
- collect aseptically/proper cleaning/decontamination of the site to be sampled
- collect an adequate amount of clinical material
- submitted in a sterile leak-proof container and should be accompanied by a relevant clinical history
- transport promptly or if delay store at 4oC
Methods of Identifying pathogens
◦ conventional methods (direct microscopy, culture, susceptibility testing)
◦ histopathological methods
◦ immunologic methods
◦ molecular methods
