HYALINE MOLDS, MUCORALES, ENTOMOPHTHORALES, DERMATOPHYTES, AND OPPORTUNISTIC AND SYSTEMIC MYCOSES Flashcards
Q: What class do Mucorales belong to?
A: Zygomycetes.
They produce large, ribbonlike hyphae that are irregular in diameter and contain occasional septa.
Mucorales
How are Mucorales organisms specifically identified?
By observing the characteristic
- saclike fruiting structures (sporangia), which produce internally spherical,
- yellow or brown spores (sporangiospores).
Where is each sporangium formed in Mucorales?
At the tip of a supporting structure called a sporangiophore.
What connects sporangiophores in Mucorales?
stolons, which attach at contact points where rootlike structures (rhizoids) may appear and anchor the organism to the agar surface.
How common are Mucorales infections compared to aspergilli?
They are a less common cause of infection than aspergilli.
In which patients are Mucorales infections an important cause of morbidity and mortality?
In immunocompromised patients.
Where are Mucorales commonly found?
On decaying vegetable matter, old bread (bread mold), or in soil.
How do Mucorales infections progress?
They are rapidly progressive.
How might immunocompetent individuals acquire Mucorales skin infections?
After traumatic injection with contaminated material.
: What is the marked propensity of mucormycosis?
Vascular invasion,
rapidly producing thrombosis
and necrosis of tissue.
What is the most common presentation of mucormycosis?
The rhinocerebral form, involving the nasal mucosa, palate, sinuses, orbit, face, and brain.
How can mucormycosis be acquired?
Through injury and contamination with spores or soil.
Are blood cultures appropriate for diagnosing mucormycosis?
No
What types of specimens should be collected for diagnosing mucormycosis?
-deep lesions or tissues and sterile sites,
-nasal discharge or scrapings,
-sinus aspirate,
-tissue specimens from vascularized tissue, -sputum,
- bronchoalveolar lavage fluids.
How should tissue biopsy specimens be transported?
They should be moistened by adding a few drops of sterile saline to the container and transported to the laboratory within 2 hours of collection.
What are some direct detection methods for mucormycosis?
nucleic acid–based testing,
recovery of the fungus from tissue, body fluids, and exudates.
What stains are used for detecting mucormycosis?
Calcofluor white and potassium hydroxide preparation.
What molecular methods are used for diagnosing mucormycosis
Nucleic acid testing on
- formalin-fixed,
-paraffin-embedded,
-fresh or frozen tissue samples,
- polymerase chain reaction (PCR) amplification.
What type of growth media should be avoided for cultivating Mucorales species?
Growth media containing high concentrations of carbohydrates.
What are the characteristics of Mucorales colonies?
-Fluffy,
-white to gray or brown hyphal growth that resembles cotton candy
-diffusely covers the surface of the agar within 24 to 96 hours
Mucorales also known as?
lid lifter
What direct detection methods are used for Entomophthorales?
Similar methods to those used for Mucorales, including the Splendore-Hoeppli phenomenon.
The formation of eosinophilic crystals that appear radiate, starlike, asteroid, or club-shaped around a fungal infection.
Splendore-Hoeppli phenomenon
