8.3-ASPERGILLOSIS+MUCORMYCOSIS Flashcards
What is the causative agent of Aspergillosis?
Aspergillus spp
What are the five most common Aspergillus species causing disease?
A. fumigatus (most common)
A. flavus
A. niger
A. terreus
A. lentulus
What is the mode of transmission (MOT) for Aspergillus?
Inhalation of conidia (spores)
What kind of fungi are Aspergillus species?
Ubiquitous saprobes (colonizing soil, plants, grains)
What type of immune reaction can Aspergillus cause in atopic individuals?
Severe allergic reactions to conidial antigens
What happens when immunocompromised patients inhale Aspergillus conidia?
Conidia germinate, forming hyphae that invade the lungs and other tissues
What is the causative agent of Aspergillosis?
Aspergillus spp.
What are the five most common Aspergillus species causing disease?
A. fumigatus (most common); A. flavus; A. niger; A. terreus; A. lentulus
What is the mode of transmission (MOT) for Aspergillus?
Inhalation of conidia (spores)
What kind of fungi are Aspergillus species?
Ubiquitous saprobes (colonizing soil, plants, grains)
What type of immune reaction can Aspergillus cause in atopic individuals?
Severe allergic reactions to conidial antigens
What happens when immunocompromised patients inhale Aspergillus conidia?
Conidia germinate, forming hyphae that invade the lungs and other tissues
Which Aspergillus species is the most common cause of aspergillosis?
A. fumigatus
What is a key morphological feature of A. fumigatus?
Sporulation occurs only from the upper half or two-thirds of the vesicle
What does an A. niger colony look like?
White with black pepper-like growth → Forms a radiate head
What does an A. flavus colony look like?
Yellow to yellow-green → Phialides cover the entire vesicle, pointing in all directions
What does an A. terreus colony look like?
Brown colonies → Phialides cover the entire vesicle
What is the first line of defense against Aspergillus conidia?
Alveolar macrophages engulf and destroy conidia
What happens if conidia survive in the lungs?
Conidia swell and germinate; Hyphae invade lung tissue and blood vessels; May cause aspergilloma (fungus ball) in preexisting lung cavities
What are the hallmark features of allergic bronchopulmonary aspergillosis (ABPA)?
Asthmatic reaction; Recurrent chest infiltrates; Eosinophilia; Type I (immediate) & Type III (Arthus) hypersensitivity
What symptoms are common in ABPA?
Difficulty breathing; Sputum with Aspergillus; Serum precipitins; Lung scarring
What can exposure to massive doses of conidia cause in normal hosts?
Extrinsic allergic alveolitis
Aside from the lungs, what other infections can Aspergillus cause?
Keratitis (eye); Nail infections; Endocarditis (heart); CNS infections
What is aspergilloma, and how does it form?
Fungus ball in preexisting lung cavities; Forms when inhaled conidia germinate & produce hyphae
What lung condition increases the risk for aspergilloma?
Cavitary diseases (e.g., tuberculosis, lung abscesses)
What are the symptoms of aspergilloma?
Cough; Dyspnea; Weight loss; Fatigue; Hemoptysis (coughing up blood)
How is aspergilloma usually treated?
Lobectomy (surgical removal of affected lung area)
Who is at highest risk for developing aspergilloma?
Immunocompromised patients (e.g., diabetics, corticosteroid users, AIDS patients)
What noninvasive Aspergillus infections can occur?
Localized colonization in: Nasal sinuses; Ear canal; Cornea; Nails
What is invasive aspergillosis?
Acute pneumonia with or without dissemination
What organs can invasive Aspergillus spread to?
Gastrointestinal tract; Kidney; Liver; Brain; Other organs
What patients are at highest risk for invasive aspergillosis?
Lymphocytic or myelogenous leukemia; Lymphoma patients; Stem cell transplant recipients; Patients on corticosteroids; AIDS patients (CD4 <50 cells/uL)
What is the main risk factor for invasive aspergillosis in stem cell transplant patients?
Allogeneic transplants (higher risk than autologous transplants)
What are the symptoms of invasive aspergillosis?
Fever; Cough; Dyspnea; Hemoptysis; Thrombosis, infarction, necrosis
What is the gold standard for diagnosing Aspergillus infections?
Culture & histopathology
What are the specimen types used for diagnosis?
Sputum; Bronchoalveolar lavage (BAL); Tissue biopsy; Blood (for disseminated infection)
What is the key histopathological feature of Aspergillus?
Septate hyphae with acute-angle branching (45° angle)
What serologic test is used to detect Aspergillus antigen?
Galactomannan antigen test
What is the first-line treatment for invasive aspergillosis?
Voriconazole
What are alternative antifungal treatments for Aspergillus?
Amphotericin B; Echinocandins (Caspofungin, Micafungin, Anidulafungin)
Is aspergilloma (fungus ball) treated with antifungal drugs?
No, it requires surgical removal (lobectomy)
Where is Aspergillus found in the environment?
Soil, decaying plants, grains, air
What group of people should be extra cautious about Aspergillus exposure?
Immunocompromised individuals (e.g., transplant recipients, HIV/AIDS patients, plant enthusiasts in high-risk groups)
What are the common specimen types used for Aspergillus diagnosis?
Sputum, respiratory tract specimens, lung biopsy tissue, blood samples
What is the key microscopic feature of Aspergillus hyphae?
Hyaline, septate, uniform width (~4 µm), and dichotomous branching
How quickly do Aspergillus species grow on culture media?
Within a few days at room temperature
How are Aspergillus species identified?
By the morphology of their conidial structures
What serologic test is positive in 80% of patients with aspergilloma or allergic aspergillosis?
ID test for precipitins to A. fumigatus
What serologic marker is used for diagnosing invasive aspergillosis?
Circulating cell wall galactomannan
What additional fungal marker helps diagnose invasive aspergillosis and candidiasis?
β-glucan detection
What are the treatment options for aspergilloma?
Itraconazole or amphotericin B + surgery
What is the first-line treatment for invasive aspergillosis?
Amphotericin B (native/lipid formulation) or voriconazole
What adjunct therapy is often given for invasive aspergillosis?
Cytokine immunotherapy
What antifungal is used for Amphotericin B-resistant Aspergillus species?
Posaconazole (for A. terreus, A. flavus, A. lentulus)
What is the treatment for less severe chronic necrotizing pulmonary aspergillosis?
Voriconazole or itraconazole
How are allergic forms of aspergillosis treated?
Corticosteroids or disodium cromoglycate
What is the main preventive strategy for individuals at high risk for invasive aspergillosis?
Avoid exposure to Aspergillus conidia
What prophylactic antifungal therapy is given to high-risk patients?
Low-dose amphotericin B or itraconazole
What is another name for mucormycosis?
Zygomycosis
What fungal order causes mucormycosis?
Mucorales
What phylum and subphylum do Mucorales belong to?
Phylum Glomerulomycota, Subphylum Mucoromycotina
What type of fungi are Mucorales?
Ubiquitous, thermotolerant saprobes
What are the leading genera of fungi causing mucormycosis?
Rhizopus, Rhizomucor, Lichtheimia, Cunninghamella, Mucor
What are the major risk factors for mucormycosis?
Acidosis, leukemia, lymphoma, corticosteroid treatment, severe burns, immunodeficiencies, dialysis with deferoxamine
What is the major clinical form of mucormycosis?
Rhinocerebral mucormycosis
What are the symptoms of rhinocerebral mucormycosis?
Edema of the involved facial area, bloody nasal exudate, orbital cellulitis
How does thoracic mucormycosis develop?
Inhalation of sporangiospores with invasion of lung parenchyma and vasculature
What causes massive tissue destruction in thoracic mucormycosis?
Ischemic necrosis
What has thoracic mucormycosis been associated with?
Contaminated wound dressings and other situations
What is the colony appearance of Mucorales?
Coarse, wooly, fluffy, white to gray or brown sporangium
How fast do Mucorales hyphae grow?
Within 1–3 days, rapidly covering the agar surface
What is the characteristic appearance of Rhizopus?
Large, broad, non-septate hyphae that produce horizontal runners (stolons), rhizoids at contact points, and sporangiospores in clusters
How does Absidia differ from Rhizopus?
Sporangiospores arise between nodes from which rhizoids are formed
What is the defining feature of Mucor?
No rhizoids (root-like structures)
What are the key microscopic features of Mucorales?
Broad hyphae (10–15 µm), uneven thickness, irregular branching, sparse septations
How do Mucorales colonies grow in culture?
Rapidly, producing abundant cottony colonies
What is the basis for identification of Mucorales?
Sporangial structures
What are the key treatment strategies for mucormycosis?
Aggressive surgical debridement, rapid administration of amphotericin B, control of underlying disease
What residual effects may occur after treatment of rhinocerebral mucormycosis?
Partial facial paralysis or loss of an eye
