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Unit 4: Micro > Pulmonary Fungal Infections 2: Opportunistic Mycoses > Flashcards

Pulmonary Fungal Infections 2: Opportunistic Mycoses Flashcards

1
Q

What are the five major human opportunistic mycoses?

A
  1. Candidiasis
  2. Cryptococcosis
  3. Aspergillosis
  4. Mucormycosis
  5. Fusariosis
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2
Q

What is the MOST IMPORTANT PREDISPOSITION to opportunistic mycoses?

A

Prolonged neutropenia

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3
Q

What organism most commonly causes Candidiasis?

A

Candida albicans

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4
Q

What are the most common diseases caused by Candida infection?

A

Thrush, vaginitis (yeast infection), diaper rash, mucocutaneous candidiasis

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5
Q

What are microscopic features that can help in the Dx of Candidiasis?

A

Oval yeast w/ single bud, but may also appear as pseudohyphae, or hyphae

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6
Q

What is the Dx? In what situations is it almost always seen?

A

Thrush; HIV+ patients not on HAART

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7
Q

What diseases (other than thrush) that can be caused by Candida overgrowth?

A

Vaginitis (“Yeast Infection”), Skin overgrowth, Folliculitis

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8
Q

What is the Dx? What is typically associated with it?

A

Disseminated Candidiasis; T cell immunity or IL-17 deficiency, possibly underlying malignancy

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9
Q

What type of cardiac pathology occurs with disseminated candida infection?

A

Right-sided endocarditis

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10
Q

Microscopy reveals gram-positive mixture of budding yeasts, pseudohyphae, and hyphae. What is the Dx?

A

Candida

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11
Q

When culturing candida, what is a vital step that must be performed?

A

Antifungal susceptibility testing (make sure the drug will work!)

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12
Q

What is the general trend for Candida infection Tx for Thrush? Skin? Vaginitis? Dissemination?

A
  1. Fluconazole
  2. Azoles
  3. Azoles
  4. Amphotericin B or Fluconazole
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13
Q

If you have any suspicion of disseminated Candida what should you do?

A

Start Tx immediately

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14
Q

Why are Candida abscesses important to drain?

A

Abscesses get poor bloodflow and therefore antifungal Tx will not reach the abscess

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15
Q

What is the bug that causes Cryptococcosis? What condition is it notorious for causing?

A

Cryptococcus neoformans; Cryptococcal meningits

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16
Q

By what route do patients acquire cryptococcus?

A

Inhalation of pigeon droppings

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17
Q

What is absolutely diagnostic for cryptococcus?

A

Sample stained with India Ink revealing wide capsules

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18
Q

Describe the pathogenesis of cryptococcosis in immunosuppressed patients

A
  1. Patient inhales organism
  2. Yeasts disseminate
  3. Patients deficient in helper T cells cannot activate macrophages.
  4. Macrophages become Trojan horses
  5. If patients also lack Abs to the capusle, bare yeast are free to roam
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19
Q

What are physical exam findings that are helpful in diagnosing disseminated Cryptococcus infection?

A

Hx of steroid use, malignant disease, transplantation, HIV

Skin lesions

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20
Q

What is unique about the body’s response to Cryptococcosis infection? Why?

A

There is very little inflammation and therefore minimal fever and stiff neck and therefore presentation is typically late in disease

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21
Q

What are typical lab findings that are suggestive of Cryptococcosis?

A
  1. Spinal Tap with India Ink stain
  2. Biopsies stained with Methenamine silver, periodic acid-Schiff, or mucicarmine
  3. Culture
  4. Serology - test for “crag” (Cryptococcal antigen)
22
Q

What will routine bloodwork show for a cryptococcal infection?

A

Very possibly will be normal because of very little inflammatory processes

23
Q

What is the general Tx for cryptococcosis? AIDS patients? Prostate Infection?

A
  • Amphotericin B plus flucytosine initially
  • For AIDS patients fluconazole for long-term suppression
  • Protstate/Pneumonia - Fluconazole or Itraconazole
24
Q

Microscopy reveals the following image. How would you describe it? What is the Dx? What is the most common bug that causes this?

A

Septate hyphae with V-shaped branches; Aspergillosis; Aspergillus fumigatus

25
Q

What are the four syndromes involving Aspergillus

A
  1. Allergic bronchopulmonary aspergillosis (ABPA)
  2. Aspergilloma
  3. Chronic necrotizing pulmonary aspergillosis
  4. Invasive Aspergillosis
26
Q

What is ABPA? In what patients is it typically found?

A

Allergic bronchopulmonary aspergillosis - Hypersensitvity to infection of bronchi by aspergillus; Asthmatics and CF patients

27
Q

What is an aspergilloma and how does it form?

A

Fungus ball that forms when aspergillus invades pulmonary cavitations originally caused by TB or CF

28
Q

What is CNPA? What is the general pathogenesis?

A

Chronic necrotizing pulmonary aspergillosis; Aspergillosis can invade lungs causing pneumonia w/ hemoptysis and granulomas

29
Q

What is invasive aspergillosis? What is it a fairly common cause of?

A

When aspergillus rapidly invades blood vessels in severely IC patients involving infarction, hemorrhage, and necrosis; Often causes death of severely IC patients

30
Q

A CXR is shown below. “Grape cluster” and “hand in mitten” morphology is shown. The patient was constantly coughing up brownish bronchial plugs. What is the Dx?

A

Allergic bronchopulmonary aspergillosis

31
Q

Chest CT shows the following. What is the Dx? What is the sign observed?

A

Aspergilloma; Air Cresent Sign

32
Q

What are underlying diseases that are normally associated with CNPA? What is your best diagnostic method?

A
  • Alcoholism, Collagen-vascular disease, chronic granulomatous disease, COPD, long-term corticosteroids
  • Aspirate from the lungs
33
Q

A CT scan shows a characteristic halo sign: ground-glass infiltrates surrounding a nodular density. What does this represent? What is the Dx?

A

Represents hemorrhage; Invasive aspergillosis

34
Q

What lab tests are useful for Dx Aspergillosis?

A
  1. Cultures from sputum, needle biopsy, bronchoalveolar lavage - Visualize with silver stain
  2. Invasive Aspergillosis - Septate hyphae branching at ACUTE ANGLES, high serum levels of galactomannan antigen
  3. ABPA - High levels of aspergillus-specific IgE, eosinophilia
35
Q

What is the Tx for ABPA? Aspergilloma? CNPA? Invasive?

A
  • ABPA - Oral corticosteroids, itraconazole
  • Aspergilloma - surgery, oral itraconazole
  • CNPA - Amphotericin B or Voriconazole
  • Invasive
36
Q

The following microscopic analysis is shown. What is the likely diagnosis? What is characteristic of this bug?

A

Mucormycosis; The hyphae branch at 90o

37
Q

Describe the pathogenesis of Mucormycosis

A
  1. Inhaled/ingested spores
  2. Invade tissues of patients w/ reduced immunity (diabetes, burns, leukemia)
  3. Proliferate in walls of blood vessels
  4. Cause necrosis of paranasal sinuses, lungs, gut
38
Q

Why is it worrisome when a patient with Mucormycosis shows Syx?

A

Patients will soon drop dead

39
Q

A patient presents with unilateral retro-orbital headache, facial pain, numbness, fever, vision loss, and black pus. What is the likely Dx?

A

Rhinocerebral Mycormycosis

40
Q

What are useful lab tests in the Dx of mucormycosis?

A
  • Bloodwork - reveals neutropenia, possibly diabetic acidosis, iron overload
  • Biopsy - NONseptate hyphae w/ broad irregular walls and branches at RIGHT ANGLES
  • Culture - colonies w/ spores contained in sporangium. Difficult to culture
41
Q

What are the useful antigen tests and CSF findings for mucormycosis?

A

There are none! HA!

42
Q

What is the primary defense against mucormycosis?

A

Neutrophils

43
Q

What is the major bug that causes Fusarium infection?

A

Fusarium solani

44
Q

How are fusarium identified microscopically?

A

Identified microscopically by banana-shaped macroconidia

45
Q

What are the three presentations of Fusarium?

A
  1. Mycotoxicosis -> Trichothecene mycotoxins
  2. Immunocompetent local infection - Skin, Cornea, Allergic sinusitis
  3. Aggressive disseminated infection
46
Q

What is the primary risk factor for fusarium infection?

A

Neutropenia

47
Q

What are fusarium virulence factors?

A
  • Immunosuppressive mycotoxins
  • Collagenases
  • Proteases
  • Adherence to prosthetic materials
48
Q

Describe the pathogenesis of disseminated fusarium

A
  1. Usually invades from sinus or wound site
  2. Fungemia
  3. Invasion of eye, sinus, pneumonia, skin lesions
49
Q

What process is must be performed to get a Dx of fusarium?

A
  1. Take samples from several sites for Multiple cultures
  2. Fusarium is ubiquitous in the environment and a single positive result is probably due to contamination
  3. Histology - yeast form must be present along with the acute branching hyphae
  4. PCR available
50
Q

What is the Tx and Px for fusarium?

A

NOTE: Fusarium is more resistant to antifungals

  1. Surgical Excision
  2. Try Amphotericin B with natamycin or voriconazole

Px in disseminated disease is POOR

51
Q

What is the process for Fusarium prevention?

A

Keep patient in HEPA-filtered room at a POSITIVE PRESSURE with filtered water and scrubbed-down showers

52
Q

What is vital in the pre-op workup for Hematopoietic Stem Cell Transplant?

A

Screen for fusarial infection. Patient will become immunosuppressed and can contract disseminated fusarium

Unit 4: Micro (7 decks)

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