aspergillosis
ASPERGILLOSIS
Aspergillosis encompasses a variety of clinical syndromes depending on host immunity factors.
It is caused by Aspergillus, an ubiquitous, soil-dwelling, filamentous fungus that grows on soil, food, dead leaves, household dust, etc. It grows best at 37ºC and the small spores are easily inhaled and deposited deep in the lungs.
The most common pathogens are Aspergillus fumigatus, A. flavus, A. niger and A. terreus.
Aspergilloma is a conglomeration of intertwined Aspergillus hyphae, fibrin, mucus and cellular debris within a pulmonary cavity or an ectatic bronchus.

Introduction

  • Encompasses a variety of clinical syndromes depending on the host immunity factor

Definition

Invasive Aspergillosis (IA)

  • A rapidly progressive & frequently fatal disease that occurs in highly immunocompromised persons
  • Most common cause of infectious pneumonic mortality in patients undergoing hematopoietic stem cell transplantation (HSCT) & is an important cause of opportunistic respiratory & disseminated infection in other immunocompromised patients
  • Inhalation of etiologic agent is extremely common but disease is rare
  • Any organ may be involved in the immunocompromised host, but sinopulmonary disease is the most frequent

Allergic Bronchopulmonary Aspergillosis (ABPA)

  • A hypersensitivity reaction to Aspergillus antigens often due to A fumigatus & typically occurs in patients with long-standing asthma or cystic fibrosis
  • It is believed that the pathogenesis involves Aspergillus-specific, IgE-mediated type I hypersensitivity reaction & specific IgG-mediated type III hypersensitivity reactions

Allergic Aspergillus Sinusitis (AAS)

  • A hypersensitivity response to the presence of Aspergillus within the paranasal sinuses & is characterized by mucoid impaction similar to that of ABPA

Aspergilloma

  • Conglomeration of intertwined Aspergillus hyphae, fibrin, mucus & cellular debris within a pulmonary cavity or an ectatic bronchus
  • Most common pulmonary involvement due to Aspergillus
  • Pre-existing lung cavity formed secondary to tuberculosis, sarcoidosis, bronchiectasis, bronchial cysts & bullae, ankylosing spondylitis, neoplasm or pulmonary infarction is the most common predisposing factor

Chronic Pulmonary Aspergillosis (CPA)

  • Subtypes include chronic cavitary pulmonary aspergillosis, subacute invasive pulmonary aspergillosis or chronic necrotising pulmonary aspergillosis
  • A pulmonary aspergillosis that commonly causes a slowly progressive inflammatory destruction of lung tissue in patients w/ underlying lung diseases & low-grade immunosuppression usually due to invasion by A fumigatus
  • No vascular involvement or dissemination to other organs

Cutaneous Aspergillosis

  • Primary cutaneous aspergillosis is usually resulting from a skin disruption site (eg intravenous devices, adhesive dressing, surgical wound, burn) creating access for the infection, or traumatic inoculation
  • Secondary cutaneous aspergillosis results from hematogenous seeding from a primary source in immunocompromised patients

Otic Aspergillosis

  • Otomycosis: A condition of superficial colonization typically due to A niger & A fumigatus
  • Usually occurs in patients with hypogammaglobulinemia, diabetes mellitus (DM), chronic eczema or human immunodeficiency virus (HIV) infection & those taking corticosteroids

Etiology

  • Caused by Aspergillus, an ubiquitous, soil-dwelling, filamentous fungus that grows on soil, food, dead leaves, household dust, etc
    • Grows best at 37°C, & the small spores are easily inhaled & deposited deep in the lungs
  • The most common pathogens are Aspergillus fumigatus, A flavus, A niger & A terreus
  • Other species can also cause disease, including A nidulans A clavatus
  • In immunocompetent persons, aspergillosis can occur in previously damaged tissue or induce allergic responses

Signs and Symptoms

Invasive Aspergillosis (IA)

  • Patient may present with:
    • Fever refractory to empirical broad-spectrum antibacterials
    • Cough
    • Pleural pain
    • Paranasal sinus findings
    • Hemoptysis

Allergic Bronchopulmonary Aspergillosis (ABPA)

  • Patient usually presents with expectoration of brown mucus plugs, wheezing, fever and pleuritic chest pain

Allergic Aspergillus Sinusitis (AAS)

  • Patient usually presents with nasal obstruction, rhinorrhea, headache and epistaxis
  • May occasionally manifest as proptosis due to extension of fungal sinusitis into the orbit

Aspergilloma

  • Aspergilloma may exist for many years without causing symptoms
  • Hemoptysis that can be severe and life-threatening
  • Chronic cough and dyspnea that are more likely due to underlying disease
  • Rarely fever

Chronic Pulmonary Aspergillosis (CPA) 

  • Chronic pulmonary symptoms (fever, cough with or without hemoptysis, dyspnea, fatigue, chest pain, sputum production, weight loss) of at least 3 months’ duration

Cutaneous Aspergillosis

  • Erythematous indurated papules that progresses into ulcerative necrotic lesions

Otic Aspergillosis

  • Patient may usually present with ear pain, pruritus, hypoacusis and otic discharge

Risk Factors

Invasive Aspergillosis (IA) 

  • Major risk factors include:
    • Prolonged neutropenia (neutrophil count <100/microL for >10 days)
    • Intensive cytotoxic chemotherapy
    • Hematopoietic stem cell transplantation or solid-organ transplantation
    • Acquired immune deficiency syndrome (AIDS)
    • Chronic granulomatous disease (CGD)
    • Critical illness without documented immunodeficiency
    • Hematologic malignancies
    • Severe aplastic anemia
    • Primary immunodeficiencies
    • Prolonged corticosteroid use
    • Cytomegalovirus disease
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