FA - Micro - Mycology Flashcards

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0
Q

Treatment for systemic mycosis?

A
  1. Fluconazole (local infection)
  2. Itraconazole (local infection)
  3. Amphotericin B (systemic infection)
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1
Q

3 features about systemic mycoses?

A
  1. ALL can cause pneumonia
  2. Can disseminate
  3. ALL caused by dimorphic fungi: cold (20C)=mold, heat(37C)=yeast.
    Only exception: Coccidioidomycosis - spherule (not yeast) in tissue.
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2
Q

Systemic mycosis can mimic what?

A

TB (granuloma formation), EXCEPT, unlike TB, have no person-person transmission.

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3
Q

Histoplasmosis - Endemic location?

A

Mississippi and Ohio river valleys.

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4
Q

Histoplasmosis cause?

A

Pneumonia.

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5
Q

Histoplasmosis special feature?

A

Macrophage filled with Histoplasma (smaller than RBC) - Histo Hides (within macros).
BIRDS (eg starlings) and BATS droppings.

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6
Q

Blastomycosis - Endemic location?

A

States east of Mississippi River and Central America.

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7
Q

Blastomycosis - cause?

A

Inflammatory lung disease - can disseminate to skin and bone.
Forms granulomatous nodules.

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8
Q

Blastomycosis - Special feature?

A

Broad-base budding (same as RBC).

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9
Q

Coccidioidomycosis - Endemic location?

A

Southwestern US, California.

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10
Q

Coccidioidomycosis - cause?

A
  1. Pneumonia
  2. Meningitis
  3. Can disseminate to bone and skin.
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11
Q

Coccidioidomycosis - Special features?

A
  1. Case rate UP after earthquakes (spores in dust are thrown up in the air and become spherules in the lungs).
  2. Spherule (MUCH LARGER than a RBC) filled with endospores.
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12
Q

Paracoccidioidomycosis - Endemic location?

A

Latin America.

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13
Q

Paracoccidioidomycosis - Special feature?

A

Budding yeast with “captain’s wheel” formation (MUCH LARGER THAN RBC).

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14
Q

Tinea versicolor - Cause?

A

Malassezia spp. (Pityrosporum spp.) ==> A yeast-like fungus (NOT A DERMATOPHYTE despite being called tinea).

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15
Q

Tinea versicolor - Pathogenesis?

A

Degradation of lipids produces acids that damage MELANOCYTES –> hypopigmented and/or PINK patches.

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16
Q

Tinea versicolor - When?

A

Can occur ANY TIME of year, but more common IN SUMMER ==> Hot, humid weather.

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17
Q

Tinea versicolor - treatment?

A
  1. Topical miconazole

2. Selenium sulfide (Selsun)

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18
Q

Tinea versicolor - Microscopic morphology?

A

“Spaghetti and meatball” appearance.

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19
Q

Other tineae?

A
Tinea pedis 
Tinea cruris (groin)
Tinea corporis
Tinea capitis 
Tinea unguium (onychomycosis, on fingernails)
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20
Q

Other tineae - Features?

A

Pruritic lesions with central clearing resembling a RING.

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21
Q

Other tineae - causes?

A

By dermatophytes - Microsporum, Trichophyton, Epidermophyton.

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22
Q

Dermatophytes - Microscopic morphology?

A

BRANCHING SEPTATE HYPHAE visible on KOH preparation with BLUE FUNGAL STAIN.

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23
Q

C.albicans - causes?

A
  1. Oral-esophageal thrush in immunocompromised (Neonates+ Steroids + Diabetics + AIDS).
  2. Vulvovaginitis (diabetes, use of antibiotics).
  3. Diaper rash
  4. Endocarditis in IVDA
  5. Disseminated candidiasis (any organ)
  6. Chronic mucocutaneous candidiasis
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24
Q

C.albicans - Treatment?

A

Vaginal –> Topical azole.
Oral/esophageal –> Nystatin, fluconazole, or caspofungin.
Systemic –> Fluconazole, ampho B, caspofungin.

25
Q

C.albicans - dimorphic?

A

YES:

  1. Pseudohyphae and budding yeasts at 20C.
  2. Germ tubes at 37C.
26
Q

Aspergillus fumigatus - causes?

A
  1. Invasive aspergillosis
  2. Allergic bronchopulmonary aspergillosis (ABPA)
  3. Aspergillomas in lung cavities (especially after TB)
  4. Some produce aflatoxins –> HCC.
27
Q

Invasive aspergillosis - features?

A
  1. In immunocompromised

2. In Chronic granulomatous disease

28
Q

Allergic bronchopulmonary aspergillosis - features?

A
  1. Asthma - CF associations.

2. May cause bronchiectasis/eosinophilia.

29
Q

A.fimugatus - Dimorphic?

A

NO - Septate hyphae that branch at 45 degree angle ==> Produces conidia in radiating chains at END of CONIDIOPHORE.

30
Q

C.neoformans - causes?

A
  1. Cryptococcal meningitis.

2. Cryptococcal encephalitis (“soap bubble” lesions in brain), primarily in IMMUNOCOMPROMISED.

31
Q

C.neoformans - Morphology + Capsule?

A

Heavily encapsulated yeast.

5-10μm with NARROW BUDDING.

32
Q

C.neoformans - Dimorphic?

A

NO!!!

33
Q

C.neoformans - where?

A

In soil, PIGEON droppings.

34
Q

C.neoformans - transmission?

A

Inhalation with hematogenous dissemination to meninges.

35
Q

C.neoformans - Culture?

A

Sabouraud agar.

36
Q

C.neoformans - Stain?

A
  1. India ink ==> Clear halo.

2. Mucicarmine ==> Red INNER CAPSULE.

37
Q

C.neoformans - diagnostic test?

A

Latex agglutination test detects polysaccharide capsular antigen and is more specific.

38
Q

Mucormycosis - target group?

A
  1. Ketoacidotic diabetics.

2. NEUTROPENIC patients (Eg leukemia).

39
Q

Mucormycosis - Pathogenesis?

A

Fungi proliferate in blood vessel WALLS when there is excess ketone and glucose ==> Penetrate cribriform plate ==> Enter brain.

40
Q

Mucormycosis - Features?

A
  1. Rhinocerebral, frontal lobe abscesses.
  2. Headache
  3. Facial pain
  4. Black necrotic eschar on face.
  5. May have cranial nerve involvement.
  6. CAVERNOUS SINUS THROMBOSIS.
41
Q

Mucormycosis - Treatment?

A

Surgical debridement + Amphotericin B.

42
Q

Mucor - Microscopy?

A

Irregular, broad, nonseptate hyphae branching at wide angles.

43
Q

P.jirocevii?

A

Pneumocystis pneumonia - Diffuse interstitial pneumonia.

44
Q

P.jirovecii - transmission?

A

Inhaled.

45
Q

P.jirovecii - CXR/CT appearance?

A

Diffuse, BILATERAL ground-glass opacities on CXR/CT.

46
Q

P.jirovecii - Diagnosis?

A

Lung biopsy or lavage.

47
Q

P.jirovecii - microscopy?

A

Disc-shaped yeast forms on METHENAMINE SILVER stain of lung tissue.

48
Q

P.jirovecii - treatment?

A
  1. TMP-SMX
  2. Pentamidine
  3. Dapsone (proph only)
  4. Atovaquone (proph only)
49
Q

P.jirovecii - prophylaxis in AIDS patients?

A

Start when CD4 count drops <200cells/mm^3 in HIV patients.

50
Q

Sporothrix schenckii - Causes?

A

Sporotrichosis.

51
Q

Sporothrix schenckii - Morphology?

A

Dimorphic - CIGAR-SHAPED budding yeast that grows in branching hyphae with rosettes of CONIDIA.
==> Lives on vegetation.

52
Q

Sporothrix schenckii - pathogenesis?

A

Spores are traumatically intoduced into the skin, typically by a thron (rose gardener’s disease) –> Local pustule or ulcer with nodules along draining lymphatics –> Ascending lymphangitis.
Little systemic illness.
==> DISSEMINATED DISEASE possible in IMMUNOCOMPROMISED host.

53
Q

Sporotrichosis - treatment?

A

Itraconazole or potassium iodide.

54
Q

“(San Joaquin)” Valley fever:

A

CODDIDIOIDOMYCOSIS.

55
Q

Tinea capitis:

A

Head + Scalp:

  1. Associated with LYMPHADENOPATHY.
  2. Alopecia.
  3. Scaling.
56
Q

Tinea corporis:

A

Torso:

==> Erythematous scaling rings (“ringworm”) + Central clearing.

57
Q

Tinea corporis can be acquired from contact with …?

A

An infected CAT or DOG.

58
Q

Tinea cruris - Occurs in …?

A

INGUINAL AREA.

59
Q

Tinea cruris - Often does NOT show …?

A

The CENTRAL clearing seen in tinea corporis.

60
Q

Tinea pedis - 3 varieties:

A
  1. Interdigital (MC).
  2. Moccasin distribution.
  3. Vesicular type.
61
Q

P.jirovecii - Originally classified as …?

A

PROTOZOAN. Now, yeast-like FUNGUS.