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Mycology > Fungi Classification (Systemic) > Flashcards

Fungi Classification (Systemic) Flashcards

1
Q

Primary systemic mycoses are different from other mycoses in the foll ways

A
  • No risk factors needed to occur
  • Etiology = dimorphic fungi
  • Begin as respiratory illness -> disseminate to sites of body if not cured
  • Symptoms = usually flu signs i.e. cough, fever, chest pain
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2
Q

Systemic mycosis transmission

A

Inhalation of fungal elements in dust

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3
Q

4 types of systemic mycoses

A

Histoplasmosis (most like Tb) - smallest size
Blastomycosis - equal size to 3rd in list
Coccidiomycosis - equal size to 2nd in list
Paracoccidiomyosis - largest size

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4
Q

Similarities between all systemic mycoses

A
  • All inhaled
  • All can cause pneumonia + dissemination to skin + bone
  • All mimic Tb in chronic cases
  • All inhaled forms are microconidia
  • All treated with Azoles/Amp B if disseminated
  • All stained with methylamine silver
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5
Q

List systemic mycoses in order of size

A

Histoplasmosis
Blastomycosis
Coccidiomycosis
Paracoccidiomyosis

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6
Q

Histoplasmosis transmission

A

Inhalation of spores in bird/bat droppings

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7
Q

Histoplasmosis symptoms

A

Acute - Asymptomatic/flu like/ Atypical pneumonia

Chronic - mimics Tb – weight loss, cough with hemoptysis

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8
Q

Define - Granuloma, caseating granuloma, necrosis

A

Granuloma - collection of macrophages due to inflammation.
Caseating granuloma - necrosis involving dead cells with no nuclei and debris.
Necrosis = tissue death – due to lack of blood supply

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9
Q

Differentiation of Tb and Histoplasmosis

A

Caseating granuloma mostly in upper lobe - like Tb
Difference on X-Ray:
- Buckshot calcifications (many calcified nodules) - Histoplasmosis
- one primary focus - Tb

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10
Q

Function of RES

A

Eticuloendothelial system (RES) removes immune complexes from the circulation in healthy persons.

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11
Q

Immunocompromised patients’ response to Histoplasmosis

A

No cell mediated response = no granuloma formed to contain fungi
Travels via blood and hits cells of RES

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12
Q

Lab ID - Histoplasma

A

Serum/urine - PCR

Acid fast - to rule out TB

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13
Q

Varieties of Histoplasma

A

H. capsulatum. Var capsulatum - small (2-3 x 3-4 um) oval yeast cells - classic

H. cap. Var. duboisii - large yeast cells (7-5 um)

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14
Q

Histoplasmosis is rarely disseminated (T/F)

A

True; mostly occurs in immunocompromised/ with underlying lung issues

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15
Q

Histoplasmosis specimen

A

Respiratory, biopsy tissue of affected site, blood , bone marrow

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16
Q

Histoplasmosis culture features

A 
Media: SDA, BHI-A
Slow growth - weeks
White colonies, septate hyphae
2 types of conidia: 
Tuberculated macroconidia 
Smooth Microconidia
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17
Q

Blastomycosis etiology

A

Blastomyces dermatitidis

  • Inhalation of microconidia spores in dead/decaying trees/bush
  • –Can’t be cultured from soil
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18
Q

Blastomycosis symptoms

A

Acute - rare; after massive exposure
Presents with lung inflammation
- fever, tachypnea, hypoxemia
Subacute (60% cases)- resembles bacterial pneumonia
- high fever, chills, productive cough
Chronic - Mimics Tb
- night sweats, W loss, cough
Immunocompromised - Disseminated lesions (pulmonary form disseminates to skin)

19
Q

Blastomycosis - Lab ID

A

Gold std - Ag test - PCR
Specimen - blood + urine

yeast-extract-phosphate agar

Lung biopsy - Broad Based Budding –> Broad –base attachment of bud to mother cell (yeast)
White with septate hyphae and lateral unicellular conidia (mould)

Skin tests also possible

20
Q

Serological tests - Blastomycosis

A

antigen - yeast culture filtrate
Immunodifussion test
Complement Fixation test
cross-reaction occurs in patients having coccidiodomycosis or histoplasmosis

21
Q

Treatment - Blastomycosis

A

Amp B - Drug of choice for rapid progression cases

Ketoconazole - less severe cases

22
Q

Coccidiomycosis - etiology

A

Coccidiodes immitis

-Found in desert areas, hot, dry

23
Q

Coccidiomycosis - transmission

A

Grows in the soil, but inhalation of a single spore can initiate infection.

24
Q

Coccidiomycosis -

A

Grows as mycelia in the cold, spherules in the heat

25
Q

What mycoses is also known by the following names:
Desert fever,
Valley fever,
San Joaquin fever

A

Coccidiomycosis

26
Q

Coccidiomycosis pathogenesis

A
  1. Inhalation of arthroconidia
  2. Invasion of lung septae = growth into spherules containing endospores
  3. Mature endospores = nodules
  4. Burst nodules = caused symptoms
  5. Second gen - isotropic growth stage
27
Q

Isotropic growth defined

A

Growth rates are same in all directions

28
Q

Skin test - Coccidiomycosis

A

Delayed hypersensitivity rxn
-Similar to Tb test
Positive result: coin like lesions/ coccidioidoma (diff from Tb test result)

29
Q

Risk factors - Coccidiomycosis

A
  1. Race: Filipinos > African American> Caucasian
  2. Age: Extremes more susceptible
  3. Sex: Males more susceptible
  4. Pregnancy
  5. Immunosuppression
30
Q

Lab ID - Coccidiomycosis

A

Specimens: respiratory (sputum, bronchoscopic), biopsy tissue from site of infection, blood and CSF for serology)

Direct microscopy – presence of spherules, mature spherules with endospores

Culture – grows readily on SDA at rtp
Reduced O2 = spherules readily produced

Biopsy = calcofluor stain

31
Q

Spherule + Mold phase in Coccidiomycosis

A

Mature spherule phase = large spherules (30-60 um)

  • produces barrel-shaped arthrospores (2.5 -4x 3-6 um)
  • arthrospores alternate with disjunctor cells (fungi cells undergoing lysis)

Mold phase has white colonies with septat hyphae

32
Q

Serology Tests for Coccidiomycosis and signs of infection and remission based on tests

A

Serology tests:
Tube preciptin
Latex particle agglutination
Complement fixation assay(CSF)

Serology Is good rising titers—infection
Declining titers —remission

33
Q

Cross-reaction does not occur in patients with histoplasmosis for Coccidiomycosis (T/F)

A

False

34
Q

Treatment for Coccidiomycosis

A

Amphotericin B, Fluconazole

35
Q

Paracoccidiomycosis

A

Paracocccidioides brasiliensisi

36
Q

Transmission - Paracoccidiomycosis

A

Inhale microconidia

37
Q

Symptoms - Paracoccidiomycosis

A

Subacute - 60% present like Tb

Fever, chills, cough, W loss

38
Q

Symptoms - Paracoccidiomycosis

A

Subacute - 60% present like Tb
Fever, chills, cough, W loss
Additional symptom: ulcers in buccal mucosa/mouth and lymphoadenopathy (abnormal sized lymph nodes)

39
Q

Differential diagnoses - Paracoccidiomycosis

A

Tb

Leishmania

40
Q

Lab ID - Yeast and mold - Paracoccidiomycosis

A

Skin scrapings = yeast cells
Result - ‘Mariner’s wheel’ - Large buds radiating from central vacuole (blood agar)

Mold grows as white colonies with septate hyphae , chlamydospores and lateral unicellular conidia (SDA)

41
Q

Paracoccidiomycosis - Specimens

A

Specimens

respiratory , aspirates, ulcerative material, biopsy tissue from site of infection, blood for serology

42
Q

Serology - Paracoccidiomycosis

A

Test for AB

43
Q

Treatment - Paracoccidiomycosis

A

Amphotericin B.

Mild cases - Sulphonamides

Mycology (6 decks)

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