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Micro U4 > Pulmonary Fungal Infection 1 > Flashcards

Pulmonary Fungal Infection 1 Flashcards

1
Q

When are Coccidioides most infectious and what do they form in order to become infection?

A

Dry summer form hyphae with alternating arthrospores

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2
Q

How are coccidioides spread

A

Formation of arthroconidia in the summer months–carried by wind and inhaled by humans

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3
Q

Who are the people most susceptible to coccidioides?

A

Snow birds moving to Southwest US

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4
Q

Where is coccidioides endemic?

A

Southwestern US

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5
Q

When coccidioides enters the terminal bronchiole of a patient what occurs

A

Changes form:
Spherules–highly resistant to eradication by immune sys
Thick, doubly-refractive wall
Filled with endospores
Wall ruptures to release endospores–new spherules

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6
Q

Are spherules and endospores seen with coccidioides pathogenesis infectious?

A

NO–no human to human spread

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7
Q

What is required in order for a patient to develop serious pneumonia or dangerous dissemination when infected by coccidioides?

A

Must be a high dose or the patient must be immunosuppressed

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8
Q

What occurs during the acute phase of a coccidioide infection?

A

Innate immunity–marcophages attempt to clear the infection and are often successful

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9
Q

When the innate immune system is inadequate for clearance of coccidioides, what occurs?

A

Chronic phase–lymphocytes and histiocytes initiate granuloma and giant cell formation

Many patient are asymptomatic or develop non-specific flu-like symptoms 60%

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10
Q

What are the symptomatic diseases that occur with coccidioides infection?

A

Valley fever or desert rheumatism

  • Fever
  • Arthralgias
  • Erythema nodosum–shins (side effect of immune response–so its working)
  • Erythema multiforme–rash on entire body
  • Chest pain
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11
Q

What is most likely to occur if a patient is immunosuppressed and gets an coccidioides infection?

A

Disseminated infection–both intracellular travel in macrophages and hematogenous spread

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12
Q

What risk factors make pts more susceptible to disseminated infection from a coccidioides infection?

A 
Advanced age
Immunocompromise
Late-stage pregnancy
Occupational high-level exposure
BLACK or FILIPINO race--this is an actual racial bias and not based on socioeconomic status
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13
Q

What are the primary sites of disseminated infection from a coccidioides infection?

A

Bones and meninges

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14
Q

When do most coccidioid infections occur?

A

Summer or autumn

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15
Q

Will a patient with a disseminated coccidioides infection (immunosuppressed) have a positive or negative PPD and what is used with the PPD test?

A

Negative

PPD with coccidioidin or spherulin

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16
Q

When erythema nudosum (adults)/ multiforme (peds) or arthralgias occurs with a coccidioides infection, what does this indicate

A

This is a HSR–meaning the immune system is working properly

Red, tender nodules on exterior surfaces –such as lower legs

Delayed cell-mediated HSR to the fungal antigens

RISK of dissemination is LOW

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17
Q

Where does a coccidioides infection disseminate to and what is found on PE?

A

Meninges–syms similar to bac meningitis but onset is slow

Bone–osteomyelitis

Skin or lymph nodes–soft tissue abscesses, hematogenously seeded

Syms:

  • Night sweats
  • Dyspnea
  • Fever
  • Weight loss
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18
Q

Biopsy of coccidioides

A

Exam for spherules

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19
Q

How should coccidiodes be cultured

A

On sabouraud’s agar at 25C

Its a cottony white mold composed of hyphae with arthrospores–INFECTIOUS

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20
Q

What is found within the CSF with a coccidiodes infection?

A 
Lymphocytic pleocytosis
Elevated protein
Hypoglycorrhachia--low glucose
Eosinophilia 
IgG
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21
Q

What a predisposed complications of coccidioides infection that must be treated even with mild disease

A 
Severe immunosuppression
DM
Black/Fillipino
Cardiopulmonary dz
Pregnancy
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22
Q

Persisting lung lesions or disseminated coccidioides infection should be treated with?

A

Amphotericin B and long-term itraconazole

Minimum of 6 months therapy

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23
Q

Meningitis caused by coccidioides infection should be treated with?

A

Fluconazole–gets through BBB

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24
Q

Is histoplasma thermally dimorphic?

A

Yes–mold in soil, yeast in tissue–real budding yeast

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25
Q

What are the two types of asexual spores that are formed by histoplasma and which one is infectious?

A

Tuberculate macroconidia–thick walls with fingerlike projections

Microconidia–smaller, thin, smooth-walled–INFECTIOUS

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26
Q

Where is histoplasma endemic

A

Ohio, Missouri, and mississippi river valleys

Acidic damp soil with high organic content

27
Q

What are the environmental factors that play a role in infection with histoplasma?

A

Soil
Bird droppings–starlings or bat guano

Excavation of contaminated soil for construction can set off an outbreak

28
Q

How do histoplasma spores engulfed by alveolar macrophages survive endocytosis and lysosomal fusion?

A

Produce bicarbonate and ammonia–raising pH and inactivating hydrolytic enzymes

29
Q

How does histoplasma get throughout the body?

A

Survives endocytosis and lysosomal fusion within macrophages by producing bicarb and ammonia, raising pH and inactivating hydrolytic enzymes

Convert to yeasts in macrophages and replicate there then spread throughout the body in macrophages

95% of patients are asymptomatic or get mild nonspecific syms then get better

30
Q

What can be seen during inflammatory response with a histoplasma infection?

A

Erythema nodosum

31
Q

High-dose exposure to histoplasma may cause?

A

Pneumonia with cavitary lung lesions on primary infection

32
Q

What occur when very young, very old, or immunosuppressed pts become infected with histoplasma?

A

Pancytopenia

ULCERATED LESIONS ON THE TONGUE

33
Q

Why isn’t PPD useful for histoplasma?

A

Too many false positives and negatives

34
Q

What are seen with mild cases of histoplasma

A

Nonspecific flu-like syms with self-limited dz

May have EN or EM

35
Q

What are some findings with spreading in lungs with histoplasma infection?

A 
Cough
Chest pain
Hemoptysis
ARDS
Cavitary lesions--characteristic sound on auscultation
36
Q

What are findings on PE with disseminated histoplasma infection?

A 
Tongue lesions
Granulomas in liver and spleen
Weight loss
Endocarditis, dysrhythmia 
GI-lesions, mass
Ocular--scars in back
CNS--mas lesions, meningismus, CN deficits 
Meningitis--fever, low CSF glucose, slow onset
37
Q

What will be seen on biopsy or bone marrow aspirate histology of histoplasma infection?

A

Oval yeast cells within macrophages

38
Q

How is histoplasma cultured?

A

Seaboard’s agar–thermally dimorphic

25C–tuberculate macroconidia–white and fuzzy

37C–yeast–slick and slimy

39
Q

What is assessed using ELISA when testing for histoplasma?

A

Histoplasma polysaccharide antigen from urine and serum

40
Q

What is the tx for histoplasma in healthy pt?

A

self-limited–monitor for 1 month

41
Q

What is the tx for pt with histoplasma that has spread to the lungs?

A

Itraconazole 6-12 wks

42
Q

What is the tx for disseminated histoplasma?

A

Amphotericin B followed with itraconazole for at least 1 year

43
Q

What is the tx for a pt with histoplasma meningitis?

A

fluconazole–penetrates spinal fluid well

44
Q

Where is Blastomyces endemic?

A

All over north america

Mostly eastern north America and great lakes region

45
Q

What are the characteristics of the mold form of blastomyces?

A

Hyphae with small pear-shaped conidia

Conidia are infectious by inhalation

46
Q

What are the characteristics of the yeast form of blastomyces?

A

Round with doubly refractive wall and single broad-based bud

47
Q

What is the infectious agent of blastomyces?

A

Conidia–mold form

48
Q

What are the virulence factors of blastomyces?

A

Yeast–produce immune-modulator BAD1 on cell surface

49
Q

What predisposes pts to dissemination of blastomyces and if untreated what occurs?

A

Immunosuppression and preexisting pulmonary dz

Untreated symptomatic cases have significant mortality

50
Q

What is found on exam with the mild form of blastomyces?

A

Nonspecific flu-like illness that is self-limiting

51
Q

What is found on exam with pneumonia caused by blastomyces?

A 
High fever
Chills
Cough with mucopurulent sputum
pleuritic chest pain
occasionally EN
52
Q

What are specific findings on exam that allow for the differentiation of blastomyces from coccidioides or histoplasma?

A

Skin lesions where the organism can be cultured

53
Q

What is used for dx of pneumonia caused by blastomyces?

A

Sputum microscopy–KOH mount

54
Q

How should a biopsy of blastomyces be prepared and what are the findings?

A

Stain with PAS or Silver

Thick-walled yeast cells with single, broad-based buds, micro abscesses, suppurating granulomatous rxn, noncaseating

55
Q

What is seen on culture of blastomyces?

A

Hyphae with small-pear shaped conidia

56
Q

What is used for tx of pts who have symptomatic but not severe blastomyces infection

A

Itraconazole

57
Q

What is used for severe blastomyces infections

A

Amphotericin B

58
Q

Meningitis caused by blastomyces is treated with?

A

Fluconazole

59
Q

What are the characteristics of the mold form of paracoccidioides

A

Thin, septate hyphae

60
Q

What are the characteristics of yeast form of paracoccidioides?!!!

A

Thick-walled with MULTIPLE BUDS

61
Q

What is seen with a more severe infection from paracoccidiodes?

A

Oral mucous membrane lesions and lymph node enlargement

62
Q

How should pus or tissue samples of paracoccidiodes be examined and what is found?

A

KOH mount—yeast cells with MULTIPLE BUDS!!

63
Q

What is the tx for paracoccidiodes?

A

Oral itraconazole for 6 months

64
Q

What is tx for severe paracoccidiodes infection

A

IV amphotericin

Micro U4 (9 decks)

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