Updated: 4/10/2021

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
    • cryptococcosis
    • 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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Questions (17)
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(M1.MC.15.9) A 47-year-old male with HIV presents to the emergency department with a 2-week history of dyspnea on exertion. He states that over the past week his symptoms seemed to have worsened and he now is experiencing a non-productive cough and low grade fever as well. He also admits that he recently stopped taking an antibiotic that was prescribed by his infectious disease physician because he could not tolerate the side effects. A chest radiograph is obtained which is demonstrated in Figure F and an arterial blood gas demonstrates a PO2 of 70%. Further labs are obtained and are notable for a CD4+ count of 184 and an LDH of 340. Which of the following figures (A-E) correctly demonstrates the causative organism of this patient's infection?

QID: 103607
FIGURES:
1

Figure A

51%

(133/260)

2

Figure B

10%

(27/260)

3

Figure C

15%

(38/260)

4

Figure D

12%

(31/260)

5

Figure E

10%

(27/260)

M 2 B

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(M1.MC.15.74) A 55-year-old man, who underwent a kidney transplant 2 years ago, presents in septic shock. He is compliant with his immunosuppressive therapy. He does not use any drugs and is sexually active with one male partner. His complete blood count returns as follows: Hemoglobin: 13.7 g/dL, white blood cell count: 4000 cells/microliter, platelets 250,000 cells/microliter. Of note, from his differential: neutrophils: 10%, lymphocytes: 45%, and monocytes: 7%. His basic metabolic profile is notable for a creatinine remaining at his baseline of 0.9 mg/dL. The patient is started on broad spectrum antibiotics, but his condition does not improve. Fungal blood cultures are obtained and grow Candida species. Which of the following was the most-likely predisposing factor?

QID: 106651
1

Defective IL-2 receptor

13%

(9/71)

2

Decreased phagocytic cell count

45%

(32/71)

3

HIV infection

32%

(23/71)

4

Failure to take suppressive trimethoprim/sulfamethoxazole therapy

4%

(3/71)

5

Renal failure

4%

(3/71)

M 1 C

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(M1.MC.14.34) A 43-year-old HIV positive woman presents with signs and symptoms concerning for a fungal infection. She is currently not on antiretrovirals, and her CD4 count is 98 cells/mm^3. Which of the following candidal infections could be seen in this patient but would be very rare in an immunocompetent host?

QID: 101493
1

Oral thrush

42%

(27/64)

2

Vaginitis

0%

(0/64)

3

Intertrigo

6%

(4/64)

4

Esophagitis

42%

(27/64)

5

Endocarditis

5%

(3/64)

M 2 D

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(M1.MC.13.188) A 50-year-old HIV-positive male presents to the ER with a two-day history of fever and hemoptysis. Chest radiograph shows a fibrocavitary lesion in the right middle lobe. Biopsy of the afflicted area demonstrates septate hyphae that branch at acute angles. Which of the following is the most likely causal organism?

QID: 101647
1

Mycobacterium tuberculosis

5%

(4/74)

2

Candida albicans

3%

(2/74)

3

Pneumocystis jeroveci

19%

(14/74)

4

Aspergillus fumigatus

70%

(52/74)

5

Naegleria fowleri

3%

(2/74)

M 2 E

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(M1.MC.12.14) A 31-year-old female undergoing treatment for leukemia is found to have a frontal lobe abscess accompanied by paranasal swelling. She additionally complains of headache, facial pain, and nasal discharge. Biopsy of the infected tissue would most likely reveal which of the following?

QID: 101473
1

Yeast with pseudohyphae

11%

(36/341)

2

Budding yeast with a narrow base

13%

(44/341)

3

Septate hyphae

22%

(74/341)

4

Irregular non-septate hyphae

43%

(146/341)

5

Spherules containing endospores

9%

(32/341)

M 1 E

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