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Erica's ID 3 > Mycology II: Dimorphic fungi > Flashcards

Mycology II: Dimorphic fungi Flashcards

1
Q

Medically important fungi are limited in their growth by what 3 things?

A
  1. Temperature (Optimal 78 degF)
  2. Low redox potential required
  3. Cell-mediated immune defenses
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2
Q

How come dimorphic fungi are more fastidious?

A

They can regulate their morphology from a mould into a yeast to survive and grow at the higher body temperature of mammals

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3
Q

Infectivity is determined by the ____ and clinical manifestations are determined by the ____

A 
Infectivity = organism
Clinical = host
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4
Q

What is the most common pathology of dimorphic fungi?

A

Chronic granulomatous response - epithelioid cells, multinucleated giant cells and a paucity of organisms

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5
Q

Route of infection with dimorphic fungi?

A

Accidental - usually by inhalation

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6
Q

Generalized life cycle of the dimorphic fungi

A

Saprophytic mould in soil –> sporulate –> host inhales –> develop into yeast at body temperature –> tissue of host grows mould on artificial media at low temps

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7
Q

Some Can Have Both Phases

A 
Sporotrichosis
Coccidioidomycosis
Histoplasmosis
Blastomycosis
Paracoccidioidomycosis
Penicilliosis
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8
Q

what animal brings about blastomycosis?

A

Your dog digging in prairie dog holes

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9
Q

Where is blastomycosis found?

A

East Mississippi basin and africa

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10
Q

How much is pulmonary blastomycosis vs disseminated

A

80% pulmonary vs 20% disseminated

Pulmonary = inhalation of spores; get chronic PNA

Disseminated = unusual; from hematogenous spread (can be chronic localized or generalized systemic)

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11
Q

Blastomycosis is considered what kind of granuloma?

A

pyogranuloma - thick-walled with single broad-based budding

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12
Q

How do you diagnose blastomycosis?

A
  • Direct stain or fungal culture

- Serology is terrible

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13
Q

What culture do you use for blastomycosis?

A

Sabouraud’s agar - white cottony colonies “lollipops”

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14
Q

What does the yeast phase look like on culture?

A

Wrinkled, heaped-up glabrous waxy and yeast-like

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15
Q

Doubly refractile wall and single broad-based budding

A

Blastomycosis

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16
Q

Tx of Blastomycosis

A

Pulm and extrapulm mild-moderate = itraconazole
Moderate-severe = Ampho B and then itraconazole

CNS = LAmB then azole
Preggers = LAmB
IC = LAmB

AmB>ITRA>VORI>FLU>KETO

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17
Q

2 types of coccidioidomycosis

A
  1. Cocci immitis

2. Cocci posadasii

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18
Q

Coccidoides is a ___ saprophyte associated with dry sandy and alkaline associated with hot summer sand mild winters and low rainfall

A

Soil saprophyte

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19
Q

Coccidoides is only found in the __ hemi

A

Western hemisphere (arizona and california)

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20
Q

Severe cocci disease is more common in which ethnic groups?

A

Filipinos, AA, Native Americans

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21
Q

Clinical features of pulmonary coccidioidomycosis

A
  • 1 to 3 wks following inhalation of dust containing arthrospores
  • Early respiratory infection in 1/3 of cases, the rest are asymptomatic
  • Nodules or cavities in 5%, thin-walled, peripheral and solitary
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22
Q

Desert rheumatism

A

Erythema nodosum + arthralgias + fever

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23
Q

Chancriform complex with ulceration, lymphangitis, and regional lymphadenopathy

A

Primary inoculation coccidioidomycosis

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24
Q

Caseating granulomas are always TB, right?

A

NOPE. Think of coccidioides too

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25
Q

30-60 micrometer thick-walled spherules filled with endospores

A

Coccidioides

26
Q

Microscopic findings of cocci

A
  • Septate hyaline hyphae with alternating arthroconidia (barrel-shaped)
  • Arthroconidia are HIGHLY infectious
27
Q

Serology of coccidioides

A

ANY titer indicates disease

  • Immunodiffusion test: positive early, useful for confirming a low CF titer
  • Complement fixation titer: positive > 1 mo reflects activity. > 1:16 indicates extrapulmonary dissemination
28
Q

Diagnostic forms of cocci

A

Alternating arthroconidia + DNA probe

Spherules

29
Q

Tx of cocci

A

PNA:

  • Moderate = fluconazole
  • Diffuse = LAmB then fluconazole

Nodule: No tx
Cavity = Observation until Sx, then fluconazole
Chronic progressive fibrocavitary = fluconazole

Extrapulmonary:
Non-meningeal = fluconazole
Meningeal = Fluconazole + lifetime maintenance

30
Q

What happens to Ab when you’re fixed in cocci?

A

Ab goes down. If you have detectable Ab, you’re not fixed yet. Don’t think it’s just “old disease”.

31
Q

Histoplasma grows best in soil with high __ content

A

Nitrogen

32
Q

Histo associated with __ or __ excreta

A

Bird or bat

33
Q

Spelunker’s disease

A

Histoplasma capsulatum

34
Q

Highest endemic area of histoplasma?

A

Ohio-Mississippi valley

35
Q

How is histoplasma capsulatum acquired?

A

Inhalation from construction, farming, spelunking, or chicken farming

36
Q

Clinical features of Histoplasma capsulatum

A
  1. Acute primary infection resembles CAP
  2. Progressive disseminated histoplasmosis (young, elderly, IC) - fever, wt loss, hepatosplenomegaly, mucosal ulcers
  3. African histoplasmosis - ulcers, nodules, osteolytic bone lesions
37
Q

Buds come off of the ___ end of the cell in histoplasmosis

A

The narrow end

38
Q

Intracellular, small parasitized yeast within macrophages

A

Histoplasma capsulatum

39
Q

Microscopic features of histo

A

Slow growing, thin, branching septate hyphae with tuberculate round, thick-walled macroconidia that are 8 to 14 microns in size
(mother cell with daughter cells around it - mariner’s wheel)

40
Q

Mariner’s wheel

A

Paracoccidioides

41
Q

High LDH and High ferritin

A

Progressive disseminated histoplasmosis

42
Q

Treat with bactrim

A

PCP and Paracoccidioides

43
Q

Where do you find paracoccidioides?

A

Subtropical areas, but mostly South America. Found in armadillos and rural agriculture.

44
Q

Cervical lymphadenopathy, edentulous (bad teeth), pulmonary disease

A

Paracoccidoides

45
Q

Tx of Paracoccidioides?

A

ITRA = VORI>KETO»»FLU

46
Q

Tx for Histo in pregnancy

A

LAmB

47
Q

Tx of mediastinal fibrosis

A

Intravascular stent placement because does not respond to antifungals. Use steroids too.

48
Q

Rose gardener

A

Sporotrichosis

49
Q

Cigar-shaped yeast

A

Sporotrichosis

50
Q

What does sporotrichosis look like?

A

Spherical to oval budding yeast, often pyriform or elongated

51
Q

Conidia of sporotrichosis look like what in mycelial phase?

A

daisies

52
Q

Clinical presentation of sporotrichosis

A
  • Lymphocutaneous form (sporotrichoid) = pulmonary inoculation that is an ulcer followed by lymphangitis. Lots of facial involvement
  • Fixed cutaneous form - verrucous; lymphangitis is absent
  • Disseminated form = seen in chronic alcoholics or sarcoid pts
53
Q

Tx for local sporotrichosis

A

Local heat (42 deg C) and oral KI

54
Q

Penicillosis found where?

A

Southeast asia

55
Q

How do you get penicillosis?

A

Inhalation during rainy seasons.

56
Q

Who gets penicillosis?

A

90% of cases are in males

57
Q

Clinical presentation of penicillosis?

A

Disseminated infection = wt loss, fever, anemia, hepatosplenomegaly, fungemia, papular skin lesions, osteolytic lesions

58
Q

Necrotizing infiltration of macrophages encgorged with characteristic intracellular yeast

A

Penicillosis caseating granulomas

59
Q

Culture of penicillosis

A

Giemsa of bone marrow
Fungal culture = any specimen
Microscopic = thin, branching septate hyphae, with phiallides bearing conidia (skeleton hands)

Yeast form:
Elliptical nonbudding with central septum

60
Q

Tx of penicillosis

A

LAmB>ITRA>FLU

61
Q

Which dimorphic fungi can be considered a zoonosis?

A

Sporotrichosis via cats

Erica's ID 3 (13 decks)

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