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Unit 4: Micro > Pulmonary Fungal Infections 1: Systemic Mycoses > Flashcards

Pulmonary Fungal Infections 1: Systemic Mycoses Flashcards

1
Q

What are major themes associated with the pulmonary systemic mycoses?

A
  • Inhaled into lung
  • Thermally dimorphic
  • NOT PERSON-TO-PERSON TRANSMISSIBLE
  • DDx includes TB but Hx points to American dirt NOT FOREIGN CROWDS
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2
Q
  1. What bugs cause coccidiomycosis?
  2. Forms?
  3. Infectious Season?
  4. Typical scenarios where infection occurs
A
  1. Coccidioides immitis
  2. Mold in soil; Spherule in tisssue
  3. Summer
  4. Areas near excavation, southwest US (San Joaquin Valley) and Latin America
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3
Q

What is the infectious component of Coccidioides? What components are noninfectious?

A

Arthrospores (arthroconidia); Spherules and endospores

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4
Q

What is this? What is important about it?

A
  1. Coccidioides spherule
  2. DIAGNOSTIC OF COCCIDIOMYCOSIS
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5
Q

What are these? What is important about them?

A
  • Coccidioides arthrospores
  • Infectious!
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6
Q

What are the majority of presentations of patients with a low to moderate dose of coccidiomycosis?

A

Betwixt asymptomatic and nonspecific flu-like illness that is self-resolving

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7
Q

Describe pathogenesis of Coccidioides

A
  1. Acute Phase: Innate Immunity (Macros) attempt to clear infection (often successful)
  2. Chronic Phase: Cell Mediated Immunity Required
  3. IF CMI not intact, patient cannot wall of infection in granulomas and bug can disseminate to bones and meninges (Macrophages as trojan horses)
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8
Q

A patient with Coccidioides infection shows the following rash. What is it? What other Syx can this patient have? Are there bugs in this lesion?

A
  • Erythema Nodosum; No bugs

Fever, arthralgia, erythema multiforme, chest pain

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9
Q

What are risk factors for those who are exposed to a large dose of coccidiomycosis to getting a serious pneumonia or dissemination?

A
  • Advanced Age
  • Immunocomp
  • Late-stage pregnancy
  • Occupational exposure (farmer, construction worker, archaeologist)
  • Black/Filipino
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10
Q

What are key findings on exam that point towards coccidioidomycosis?

A
  • Travel/residence in endemic area
  • PPD with coccidioidin or spherulin
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11
Q

What must one be conscious of when administering a PPD for coccidioidomycosis?

A

You will get a + PPD if exposed w/ cleared or contained infection. Negative exam if unexposed or DISSEMINATED (immunocompromised)

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12
Q

Why is observing Erythema Nodosum in a patient with Coccidioidomycosis a good sign?

A

Infection probably isn’t disseminated

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13
Q

What are important diagnostic tests for coccidioidomycosis infection?

A
  • Spherules on biopsy are diagnostic
  • Cutulre on Sabouraud’s agar at 25C (CULTURES ARE INFECTIOUS)
  • Serology - positives very reliable (specific) but there are some false negatives
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14
Q

Tx for mild coccidioidomycosis? Persistent infection/dissemination?

A
  • Mild - generally nothing
  • Persistent Infection/Dissemination- Amphotericin B and long term Itraconazole (POTENTIALLY YEARS OF TX)
  • Meningitis - Fluconazole and potentially intrathecal ampho B
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15
Q

What is the most common systemic mycosis?

A

Histoplasma capsulatum

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16
Q

What are the two types of asexual spores of Histoplasma?

A
  • Tuberculate macroconidia
  • Microconidia
17
Q

Where is histoplasma normally found? What reproductive processes are histo capable of?

A
  1. In acidic damp soil w/ high organic content (Ohio, Missouri, Mississippi) river valleys
  2. Thermally dimorphic - Mold in soil, yeast in tissue
18
Q

What would be a possible scenario which leads to infection with histoplasma?

A

Eating soil, bird or bat droppings, excavation/construction

19
Q

Describe the pathogenesis of histoplasma

A
  1. Inhalation of spores
  2. Innate immunity can kill low dose but can be overwhelmed by high doses
  3. Macros engulf spores which may survive endocytosis and lysosomal fusion via bicarb and NH3 production
  4. Spores -> yeast w/i macros and replicate
  5. Macros as trojan horses
20
Q

A patient with histoplasma presents with the following lesion. What does this indicate?

A

Tongue lesion is a sign of histoplasma dissemination. May indicate immunosuppresion and possible pancytopenia.

21
Q

What are significant red flags in the exam indicating a person has a Histoplasma infection?

A
  • Acute febrile illness
  • Hx: Residence/travel to an endemic river valley; Occupational Exposure (Construction, Birds, Bats)
  • Lung Exam: cough, chest pain, hemoptysis, ARDS, cavitary lesions
  • Eye Exam: Scars
  • PPD: NOT USEFUL
22
Q

Useful tests for Histoplasma Dx?

A
  • Bloodwork - pancytopenia found in patients w/ disseminated cases
  • TWO cultures - Thermally Dimorphic - culture at 25 and 37 C
23
Q

Tx for Histoplasma infection for mild cases? Pulmonary cases? Disseminated? Meningitis?

A
  • Mild - monitor progress
  • Pulm - oral itraconazole 6 - 12 weeks
  • Diss - amphotericin B followed by 1 year of itraconazole
  • Menin - Fluconazole (penetrates spinal fluid well)
24
Q

What is the bug that causes Blastomycosis? Where is it found? What for is infectious? Route?

A

Blastomyces dermatidis; North America in Great Lakes Region in rich wet soil; Conidia by inhalation

25
Q

Describe the pathogenesis and virulence factors of blastomycoses

A
  • Monos/Macros/Neutros readily kill the conidia but once yeast conversion occurs, innate immunity slows down
  • YEAST produce BAD1 immune-modulator on cell surface
26
Q

What factors predispose a patient to blastomycosis infection?

A

Immunosuppresion and preexisting pulmonary disease

27
Q

Describe the mild for of blastomycosis. Pneumonia? Chronic illness? Fast/Severe Form?

A
  • Mild - Nonspecific flu-like Syx
  • Pneumonia - fever, chills, cough w/ mucopurulent sputum
  • Chronic - looks like TB - weight loss, night sweats, hemoptysis
  • Fast/Severe Form - ARDS + Fever
28
Q

What tests are useful in the Dx of blastomycosis?

A
  • Sputum microscopy (KOH mount) - thick-walled yeast
  • Culture - hyphae with small pear-shaped conidia
29
Q

A patient with the following skin lesions and bone/joint has blastomycosis. What form of the disease does he have?

A

It could be any of the forms

30
Q

A lung biopsy was taken and the following bug grew in culture. What is the Dx? What are the distinguishing factors?

A

Hyphae w/ small pear-shaped conidia

31
Q

What is the Tx for symptomatic Blastomycosis? Severe? Meningitis? Focal loci?

A
  • Symptomatic - Itraconazole
  • Severe (CNS) - Amphotericin B then Itraconazole
  • Meningitis - Fluconazole
  • Focal loci - surgical excision
32
Q

What bug causes paracoccidioidomycosis? Where is it found?

A

Paracoccidioides brasiliensis; Rural Latin America

33
Q

What is the pathogenesis of paracoccidioides?

A
  1. Spore inhalation
  2. Early lesions in lungs
  3. Generally asymptomatic
  4. Severe infection - oral mucousa and lymph nodes
  5. Dissemination in IC’ed or chronic
34
Q

What findings on exam would be helpful with the Dx?

A
  • Juvenile/Acute Form: Peds/IC’ed; Severe, Fever, Malaise, Weight Loss, Lymphhepatosplenomegaly
  • Adult/Chronic Form: Less severe; can be latent for up to 30 years, pulmonary Syx
35
Q

What findings on lab would be useful for Paracoccidioides infection Dx?

A
  • Pus/Tissue Sample on KOH mount: Mommy yeast cell with budding babies
36
Q

Tx for paracoccidioidomycosis?

A
  • Oral itraconazole for six months
  • Severe - IV Amphotericin B and oral azole afterwards
  • Remove Risk Factors - Correct anemia, improve diet, rest, smoking/drinking cessation
37
Q

Of the mycoses in this section, which is the most opportunisitic?

A

Paracoccidioidomycosis

Unit 4: Micro (7 decks)

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