MYCO & VIROLOGY L3 (Midterms- Opportunistic and Systemic) Flashcards
Seen in immunocompromised patients.
Commonly encountered as saprobes
Opportunistic mycoses
One of the most commonly encountered fungi in the lab (common in peanuts)
Aspergillus spp.
- Second most isolated fungus after Candida spp.
- Widespread in the environment
- Conidia are easily dispersed in the environment
Aspergillus spp.
Aspergillus spp. are transmitted by?
Inhalation
Aspergillus spp. septate hyphae branches out at _____ degrees?
45
In the _________, conidia of aspergillus spp. germinate and invade the tissue
lung air spaces
IDENTIFY based on clinical manifestations:
- Pulmonary or sinus fungus balls
- Allergic bronchopulmonary aspergillosis
- External otomycosis (auditory canal)
- Mycotic keratitis
- Onychomycosis (nail and surrounding tissues)
- Sinusitis
- Endocarditis
Aspergillus spp.
In terms of structure, aspergillus has a _______
hyphae and conidiophore. And if you look closely, they have a vesicle at the end of the condiophore, these vesicles have ________ attached to them
septated; mutulae
Its other characteristics include an erect conidiophore arising from a foot cell within the vegetative hyphae
Aspergillus spp.
A supporting structure where the phialides attached.
Metulae
Conidia of aspergillus spp. are produced from the?
phialides
What makes this unique is that it has a metula/metulae before the phialide
Aspergillus spp.
Laboratory dx for aspergillus spp.
- Antigen-protein based assays
- Nucleic Acid Amplification Assay
What is the downside of Antigen-protein based assays?
not true to all species of Aspergillus because it can have cross reactions
This organism has a fungus ball
Aspergillus spp.
This assay is used for monitoring patients who are at high risk ofdeveloping invasive fungal infections
Antigen-protein based assays
What is the downside of Nucleic Acid Amplification Assay?
not readily available for fungi in general
Enumerate the different species of aspergillus
- A. fumigatus
- A. flavus
- A. niger
When cultured it rapidly grows (1-5 days) and manifests a yellow-green colony
Aspergillus flavus
Microscopically, its phialides give rise to short chains of yellow orange elliptical or spherical conidia
A. flavus
Produced directly from the vesicle
Uniseriate
Produced from a primary row of cells called metulae
Biseriate
Macroscopically, it produces darkly pigmented, roughened spores
A. niger
Microscopically, its hyphae are hyaline and septate
A. niger
Aspergillus niger’s colony mature within?
2-6 days
Young colony of A. niger appears?
yellow
Its appears black dotted surface due to conidia
Old colony of A. niger
Remains buff or cream colored
reverse colony of A. niger
IDENTIFY based on structure:
- Septate hyphae
- Long condiophores
- Large metulae
- Smaller phialides (biseriate)
A. niger
These can also be commonly seen in clinical laboratory but its association with the clinical disease that it can cause is still unclear.
A. niger
A. niger is known to cause?
fungus ball and
otitis externa
It is a rapid grower (2-6 days), has blue-green appearance and is thermotolerant at 45C
A. fumigatus
IDENTIFY based on microscopic characteristics:
- Septate hyphae
- “foot cell” at base -L or T-shaped
A. fumigatus
Differentiate the different species of Aspergillus based on their rate of growth.
A. fumigatus: rapid grower; 2-6 days
A. flavus: rapid grower; 1-5 days
A. niger: rapid grower; 2-6 days
Common environmental isolates associated with soil and plants
Mucorales
They contaminate grains, breads, and fruits and are most often associated with infections of the sinuses, lungs, and skin of immunocompromised patients
Mucorales
IDENTIFY based on general microscopic characteristics:
- Saclike fruiting structures (sporangia)
- Sporangium is formed at tip of sporangiophore
- Septate hyphae
- Rootlike structure
Mucorales
What do you call the septate hyphae of mucorales?
stolon
The rootlike structure of mucorales is called?
rhizoids
Agents of Mucorales
- Cunninghamella
- Lichtheimia
- Mucor
- Rhizopus
Central axis of the sporangia
(multispored structure)
columella (singular)
Swelling of the sporangiophore below the columellae (plural)
Apophysis
Some species (of mucorales) also produce _____ that hold the sporangiophore within the soil or growth substrate. Which are then connected to a branching root, or ______
rhizoids; stolon
These attach at contact points where rootlike structures (rhizoids) may appear and anchor the organism to the agar surface
Stolons
Marked propensity for vascular invasion. Rapidly produce thrombosis and necrosis of tissue
Mucormycosis
Common presentation of mucomycosis
Rhinocerebral form
Potential means of retroorbital spread (i.e., invasion into the brain)
Perineural invasion