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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
30-60 micrometer thick-walled spherules filled with endospores
Coccidioides
26
Microscopic findings of cocci
- Septate hyaline hyphae with alternating arthroconidia (barrel-shaped) - Arthroconidia are HIGHLY infectious
27
Serology of coccidioides
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
Diagnostic forms of cocci
Alternating arthroconidia + DNA probe Spherules
29
Tx of cocci
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
What happens to Ab when you're fixed in cocci?
Ab goes down. If you have detectable Ab, you're not fixed yet. Don't think it's just "old disease".
31
Histoplasma grows best in soil with high __ content
Nitrogen
32
Histo associated with __ or __ excreta
Bird or bat
33
Spelunker's disease
Histoplasma capsulatum
34
Highest endemic area of histoplasma?
Ohio-Mississippi valley
35
How is histoplasma capsulatum acquired?
Inhalation from construction, farming, spelunking, or chicken farming
36
Clinical features of Histoplasma capsulatum
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
Buds come off of the ___ end of the cell in histoplasmosis
The narrow end
38
Intracellular, small parasitized yeast within macrophages
Histoplasma capsulatum
39
Microscopic features of histo
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
Mariner's wheel
Paracoccidioides
41
High LDH and High ferritin
Progressive disseminated histoplasmosis
42
Treat with bactrim
PCP and Paracoccidioides
43
Where do you find paracoccidioides?
Subtropical areas, but mostly South America. Found in armadillos and rural agriculture.
44
Cervical lymphadenopathy, edentulous (bad teeth), pulmonary disease
Paracoccidoides
45
Tx of Paracoccidioides?
ITRA = VORI>KETO>>>>FLU
46
Tx for Histo in pregnancy
LAmB
47
Tx of mediastinal fibrosis
Intravascular stent placement because does not respond to antifungals. Use steroids too.
48
Rose gardener
Sporotrichosis
49
Cigar-shaped yeast
Sporotrichosis
50
What does sporotrichosis look like?
Spherical to oval budding yeast, often pyriform or elongated
51
Conidia of sporotrichosis look like what in mycelial phase?
daisies
52
Clinical presentation of sporotrichosis
- 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
Tx for local sporotrichosis
Local heat (42 deg C) and oral KI
54
Penicillosis found where?
Southeast asia
55
How do you get penicillosis?
Inhalation during rainy seasons.
56
Who gets penicillosis?
90% of cases are in males
57
Clinical presentation of penicillosis?
Disseminated infection = wt loss, fever, anemia, hepatosplenomegaly, fungemia, papular skin lesions, osteolytic lesions
58
Necrotizing infiltration of macrophages encgorged with characteristic intracellular yeast
Penicillosis caseating granulomas
59
Culture of penicillosis
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
Tx of penicillosis
LAmB>ITRA>FLU
61
Which dimorphic fungi can be considered a zoonosis?
Sporotrichosis via cats

Erica's ID 3 (13 decks)

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