Hyaline Opportunists Flashcards
What is the name for aseptate, hyaline fungi?
Mucorales, formerly Zygomycetes
Do healthy people get opportunistic infections?
NO
What 4 organisms are agents of mucormycoses?
Rhizopus, Mucor, Rhizomucor, and Lichtheimia (formerly Absidia)
What is the most common agent of mucormycoses and is difficult to treat?
Rhizopus
Where is Mucorales commonly found?
in nature, soil
How is Mucorales commonly obtained by the body?
inhalation
In what case are you more likely to develop Mucorales?
Type I Diabetics (poorly controlled or in ketoacidosis)
What is the most common clinical presentation of Mucorales?
Rhinocerebral; nasal sinus infection that spreads to orbits or the brain
What is the second most common clinical presentation of Mucorales?
pulmonary and systemic infections (especially in Bone Marrow transplant patients)
What is commonly seen in direct examination of Mucorales aspiration or biopsy?
Necrotic or dead tissue, aseptate hyphae with 90* branching and broad ribbon like shape
What do Mucorales look like on culture plates?
rapid, profuse growth (lid lifters); aseptate hyphae; sporangium, sac-like structures containing conidia; may have rhizoids or root-like structures
Does Mucor have rhizoids?
NO
What is the most common Mucorales causing disease?
Rhizopus
Does Rhizopus have rhizoids?
YES, distinct rhizoids at the base of the sporangiophore; sporangia can also collapse creating umbrelllas
This Mucorales has delicate rhizoids at points between the sporangiophores (intermodal).
Lichtheimia (Absidia)
Where is septate, hyaline fungi often found?
granulocytopenia (neutropenia)
What is the most commonly found organism in patients with neutropenia?
Aspergillus
Aspergillus found as an overgrowth in an old cavity in the lung is called what? It does not grow in living tissue (not invasive)
Fungus Ball
What is the single most predictive factor of aspergillosis with a very high mortality (even with treatment)?
Neutropenia
What can cause neutropenia?
cancer (leukemia), transplant
When looking at a sputum or tissue biopsy, what do Aspergillus look like?
septate hyphae with parallel sides which usually branch at acute 45* angels and may invade into blood vessels.
What enzyme does Aspergillus produce?
elastase
Where does vascular invasion of Aspergillus take place and what causes death?
Especially in the lung and death due to loss of blood supply.
What is the most common species of Aspergillus?
Aspergillus fumigatus (followed by A. flavus, A. niger, and A. terreus)
What color does Aspergillus fumigatus appear?
blue-gray/blue-greenish colonies
Describe the microscopic characteristics of A. fumigatus.
conidia cover only half of the vesicle (looks like hair standing straight up)
Describe plate colony color of Aspergillus flavus.
Yellow/brown colonies
Describe the microscopic view of A. flavus.
conidia cover most of the vesicle and have rough (spiny) conidiophores (spiny dots)
What does a plate colony of Aspergillus terreus look like?
Cinnamon colored colonies
Describe the microscopic view of A. terreus.
cover upper half of the vesicle and usually fan outward (do not have spiny dots)
Describe the plate color appearance of Aspergillus niger.
colonies are black dots on white (peppered)
Describe the colony appearance of A. niger.
black color, phialides cover the entire vesicle
These colonies appear greenish or yelow on plates and have a brush like appearance with NO vesicle (look like fingerlike projections)
Penicillium
This organism appears as long, tapered phialides, with oval conidia; very delicate.
Paecilomyces
This organism appears as a long string of light bulb conidia.
Scopulariopsis
These appear as oval conidia that group up in clusters.
Acremonium
This organism appears as spiny/rough macroconidia and resemble Histoplasma capsulatum but are not pathogenic (can also appear as cigar-shaped microconidia).
Sepedonium
These organisms appear as single conidia on ends or conidiophores, look like lollipops.
Pseudallescheria boydii and Scedosporium boydii
This organism is a plant pathogen, found in grains, hospitals, and potted plants.
Fusarium
In what two medical conditions is Fusarium found?
Transplant patients (100% mortality) and keratitis (contact lens’ and solution)
What is the typical microscopic appearance of Fusarium?
sickle or canoe shaped
Describe the mortality rate in disseminated aspergillosis in immunocompromised patients.
Breaks apart fungus ball and has a very high mortality
