Aspergillus Flashcards
What are the pathogenic species of the Genus Aspergillus
A. fumigatus
A. flavus
A. niger
A. terreus
Aspergillus morphology
Grows as mold hyphae that form acute angles at their branches, 45 degree angles or less.
Septate hyphae.
When exposed to air they grow conidiophores, which are a specialized hyphae segment.
The conidiophore bear terminal vesicles, which give off dozens of phialides, that each produces dozens of conidia spores. These spores are how the disease is transmitted, when they are inhaled.
Aspergillus fumigatus infection, clinical disease and morphology in the body
From Agostan, two forms:
In healthy people: forms a fungus ball, it grows within an existing cavity and then forms a granuloma/tuberculoid lesion within the lung, that can be removed by surgical resection
Invasive form: It spreads into the lung and causes necrotizing pneumonia, and can rapidly disseminate to other organs with a serious threat of meningitis.
From sketchy, 3 (4) types.
ABPA: Allergic Bronchopulmonary Aspergillosis. A type 1 hypersensitivity reaction. Wheezing, fever, and Migratory pulmonary infiltrate. Increased IgE levels. Cystic fibrosis patients are at high risk.
Aspergillomas, fungus balls: Patients with an otherwise normal immune system, but pre-existing or comorbid TB, Klebsiella, COPD/emphysema are at risk because they have pre-existing cavities in their lung. The aspergillus grows within that pre-existing cavity and forms a tuberculoid lesion.
This type can progress to Chronic Pulmonary Aspergillosis.
Angioinvasive Aspergillosis: Seen in immunocompromised patients. Especially patients with neutropenia from leukemia or lymphoma. Invades the blood vessels and quickly disseminates. causes hemoptysis, coughing blood. Disseminates to kidneys, heart, brain. Causing kidney failure, acute endocarditis, and ring enhancing brain lesions on CT and neurological symptoms. Also causes paranasal sinus necrosis (may also occur in mucor).
What is used to stain Aspergillosis infection?
Grocott stain. GMS stain. Grocott methenamine Silver stain.
aka Gomori Silver stain, stains specifically the fungal cell walls.
Can also be seen with the PAS periodic acid schiff stain which stains for glycogen, glycoproteins, and mucinous substrates.
What is the treatment for aspergillosis?
Amphotericin B and surgical resection for angioinvasive aspergillosis
For less severe infections, ABPA or aspergillomas voriconazole, and surgical resection
What is unique biochem property does aspergillus share with candida, which most fungi other fungi do not?
Catalase positive.
What is the significance of aflatoxin? What species produces it?
Aflatoxin is a carcinogen, especially to liver cells. Significant risk for hepatocellular carcinoma.
It is made by Aspergillus flavus
How is aspergillus transmitted?
By inhalation of the spores given off of the conidiospore.
Often from peanuts or asparagus crops.
