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Aspergillus

Terms in this set (18)

Aspergillus: A. fumigatus
-Most common cause of invasive aspergillosis.
-Well documented allergen.
Aspergillus: A. flavus
-2nd or 3rd most common cause of invasive disease, aflatoxin production, allergic reactions
Aspergillus: A. niger.
-2nd or 3rd most common cause of invasive disease, aspergilloma, otomycosis, allergies
Aspergillus: Growth and Reproduction
-Filamentous mold.
-Septate hyphae (at acute 45 degree angles)
-No sexual stage observed in patients.
-As sexual aerial hyphae with conidiophores tha tgenerate conidia that become airborne.
Aspergillus: Nutrition.
-Generate digestive enzymes to breakdown and digest local environment.
-Also generate mycotoxins of unknown function.
-Most notable is aflotoxin, which is carcinogenic and hepatotoxic if ingested (problems for farm animals, peanut butter).
Aspergillus: Habitat.
-Occur in nature on living and dead organic matter.
-Can also grow indoors on wet surfaces.
Aspergillus: Transmission.
-Inhaled airborne spores (conidia) which germinate or cause allergic reaction.
-Can become infected and exposed to toxins if contaminated food is eaten.
Aspergillus: Epidemiology.
-Inhalation and subsequent infections and allergies occur the most in summer and fall months.
-Symptoms and severe infections are only seen in those of some level of immunosuppression.
Aspergillus: Clinical manifestations: Allergic reactions.
1.) URT allergies (hay fever, Aspergillus DZ)
2.) Hypersensitivity pneumonitis (seen in farmers and outdoor workers-due to chronic lung inflm from spores)
3.) Allergic bronchopulmonary aspergillosis (ABPA)- in CF patients and asthmatics: Actual colonization of resp tract with aspergillus colonies. Brown mucus, can cause fibrosis.
4.) Allergic fungal sinusitis- germination of spores in sinus cavities.
Aspergillus: Clinical manifestations: localized infections: Aspergilloma
-Aspergillus spores germinate in an old cavity in the lung caused by previous infection (IE. TB).
-Is self contained withing cavity forming fungal ball visible on xray.
-Patients can be asymptomatic and can have cough, weightloss, chronic cough with hemoptysis, and malaise.
Aspergillus: Clinical manifestations: localized infections: Chronic necrotizing Aspergillus pneumonia (CNAP)
-Not associated with pre-existing cavity.
-Starts as sub-acute pneumonia and cavitates over weeks or months.
-Fever, cough, night sweats and weight loss can lead to a confusion with tuberculosis.
Aspergillus: Clinical manifestations: localized infections: Otomycosis
-Chronic and found in the tropics.
-Growths within the ear canal (fungal forests)
Aspergillus: Clinical manifestations: localized infections: Skin/subcutaneous infections.
-Spores enter at site of trauma.
-Can result in bloodstream dissemination.
Aspergillus: Clinical manifestations: invasive Aspergillosis: Lung infection.
-Spores not restricted to preformed cavity and extend hyphae into new areas of the lung.
-Patients exhibit fever, cough, chest pain and breathlessness.
-Life threatening and high mortality.
Aspergillus: Clinical manifestations: invasive Asperfillosis: Blood stream dissemination.
-Can spread to to other organs (heart, eye, kidney, brain and skin)
-Highest mortality.
Aspergillus: Diagnosis
-Imaging is crucial (xray, CT)
-Biopsy
-Direct microscopic examination (septate hyphae seen with 45 degree branches.
-Culutre is slow and requires up a week from growth to appear.
-Antigen (galactomannan) in serum.
-Skin test (APBA)
-PCR
Aspergillus: Treatment
-Corticosteroids for allergic steroid with anti fungals for allergic rxns.
-Surgery to remove funal balls
-Voriconazole is for invasive form.
Aspergillus: Prevention
-No vaccines.
-Fungal prophylaxis.
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