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Updated: Mar 6 2022

Opportunistic Mycoses

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  • Snapshot
    • A 40-year-old woman presents to the emergency room with a week of fever, cough, and hemoptysis. She has a history of HIV and has been noncompliant with her medications and has a history of tuberculosis that was adequately treated. She reports feeling increasing fatigue. A chest CT shows nodules with a halo sign. A bronchoalveolar lavage with biopsy eventually reveals fungus with septate hyphae branching at acute angles invading into lung tissue. (Invasive aspergillosis)
  • Candida albicans
    • Classification
      • yeast with budding and pseudohyphae
      • germ tube formation at 37°C (diagnostic)
      • can be part of normal flora
    • Risk factors
      • immunocompromised status
      • hospital admission, especially in the ICU
    • Clinical syndrome
      • immunocompetent hosts present with skin and mucous membrane infections
        • oral thrush
          • white plaque on the tongue that can be scraped off
          • associated with use of inhaled corticosteroids
        • candidal intertrigo
          • well-demarcated, erythematous, and itchy plaques in the skin folds
        • vulvovaginitis
          • thick "cottage cheese" white discharge
          • itchiness
      • immunocompromised hosts usually present with systemic disease
        • local infection is due to T-cell deficiency while systemic infection is due to neutropenia
        • esophagitis
          • dysphagia and throat pain
          • endoscopy shows white plaques along the esophagus
        • endocarditis
          • associated with IV drug users
          • fevers and a new murmur
        • disseminated/invasive candidiasis
          • fever and septic shock
    • Studies
      • definitive diagnosis requires blood or other tissue culture
      • wet mount with potassium hydroxide prep of vaginal fluid shows yeast with pseudohyphae
      • germ tube formation at 37°C
    • Treatment
      • nystatin
        • local infections
      • azoles
        • local and systemic infections
        • first-line if the fungus is not resistant
      • echinocandins
        • systemic infections
        • first-line due to increased resistance to azoles
      • amphotericin B
        • systemic infections
        • second-line or for pregnant women
  • Cryptococcus neoformans
    • Classification
      • urease-positive monomorphic encapsulated yeast with 5-10 μm narrow budding
      • transmitted via inhalation and found in soil and pigeon droppings
    • Risk factors
      • immunocompromised status
      • HIV/AIDS patients
    • Clinical syndrome
      • pulmonary cryptococcosis
        • most common site of infection
      • cryptococcal meningitis
      • cryptococcal encephalitis
      • presents with fevers, headaches, and generalized malaise
    • Studies and imaging
      • head imaging with computed tomography (CT) or magnetic resonance imaging (MRI)
        • soap bubble lesions
        • variable enhancing lesions
        • hydrocephalus
      • detection of capsular antigen in serum or cerebrospinal fluid (CSF)
        • latex agglutination test
      • CSF studies
        • culture on Sabouraud agar
        • India ink stain shows yeast with clear halos
        • mucicarmine shows yeast with red inner capsules
    • Treatment
      • amphotericin B + flucytosine
        • for 10-14 days
      • fluconazole
        • after treatment with amphotericin B and flucytosine
        • maintenance and suppressive therapy
  • Aspergillus spp.
    • Classification
      • most commonly Aspergillus fumigatus
      • monomorphic fungus with septate hyphae branching at acute angles (45 degrees)
      • found in soil and decomposed material
      • transmission via inhalation of spores called conidia
    • Risk factors
      • immunocompromised status
      • hematologic malignancy
      • asthma
      • pre-existing lung disease
    • Clinical syndrome
      • invasive aspergillosis
        • invasive infection of the lung
        • causes persistent fever and cough with hemoptysis
      • aspergilloma
        • mycetoma ("fungal ball") in pre-existing cavity (i.e., tuberculosis)
        • causes cough with hemoptysis or asymptomatic
      • allergic bronchopulmonary aspergillosis (ABPA)
        • hypersensitivity reaction in patients with cystic fibrosis or asthma
        • causes bronchiectasis and eosinophilia
        • causes cough with hemoptysis, brownish black mucus plugs in expectorate, and wheezing
    • Studies and imaging
      • invasive aspergillosis
        • nodules with halo sign and cavitary lesions on computed tomography (CT)
        • pathologic examination showing invasive hyphae into tissue
        • positive cultures or serology
      • aspergilloma
        • mobile round or ovoid mass on chest CT
        • positive cultures or serology
      • ABPA
        • bronchiectasis on CT
        • elevated eosinophils or IgE in ABPA
    • Treatment
      • invasive aspergilloma
        • voriconazole + amphotericin B
          • first-line
        • caspofungin
          • second-line
      • aspergilloma
        • surgical resection
      • ABPA
        • steroids
          • first-line
  • Mucormycosis
    • Classification
      • Mucor and Rhizopus spp.
        • fungi with irregular, broad, and nonseptate hyphae branching at wide or right angles
        • found in soil and decomposed material
        • transmission via inhalation of spores or direct inoculation through trauma
    • Risk factors
      • diabetic ketoacidosis
      • immunocompromised status
      • trauma or burns
    • Clinical syndrome
      • mucormycosis (rhinocerebral infection)
        • headache
        • congestion
        • sinus pressure and pain
        • black necrotic eschar on face, particular nares or palate
    • Studies and imaging
      • computed tomography (CT) shows air-fluid levels in the sinuses and bony destruction
      • biopsy of affected tissue shows nonseptate hyphae with wide-angle branching
    • Treatment
      • amphotericin B
        • first-line
      • isavuconazole
        • second-line
      • surgical debridement
        • for patients who need it, in addition to antifungals
  • Pneumocystis jiroveci
    • Classification
      • a yeast-like fungus
      • transmission via airborne
    • Risk factors
      • immunocompromised status (e.g., hyper IgM syndrome)
      • HIV
      • smoking
    • Clinical syndrome
      • interstitial pneumonia
        • progressive exertional dyspnea
        • chest pain
        • nonproductive cough
        • fever and chills
        • hemoptysis is rare
    • Imaging
      • chest radiograph will show bilateral infiltrates
      • computed tomography will show patchy ground-glass opacities sand pneumatoceles
    • Studies
      • histology with methenamine silver, Diff-Quik, or Wright stain of lung tissue
        • disc-shaped yeast
    • Treatment
      • trimethoprim-sulfamethoxazole (TMP-SMX)
        • prophylaxis (CD4+ count < 200 cells/mm3) and first-line therapy
      • corticosteroids
        • severe cases
      • pentamidine, atovaquone, or dapsone
        • second-line therapy if resistant to TMP-SMX or allergic
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