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Microbiology Part 2 > Lec40 Fungi II > Flashcards

Lec40 Fungi II Flashcards

1
Q

When you see broad ribbon-like hyphae with right angle branching what should you think?

A

zygomycetes

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2
Q

What is pathogenesis of mucormycosis?

A
  • invades into blood vessels
  • destroys tissue
  • wide, nonseptate ribbon-like hyphae with white right angle branching
  • move from nasal/palate area up into brain
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3
Q

What are two other names for mucormycosis

A
  • phycomycosis

- zygomycisis

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4
Q

What are the types of zygomycetes fungi? which most common?

A
  • rhizopus, absidia, apophysomyces, mucor, rhizomucor, cunninghamella
  • rhizopus oryzae and rhizopus rhizopodiformia cause most cases
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5
Q

What are risk fators for rhinocerebral mucormycosis?

A
  • DM [especially DKA]
  • desferoxamine therapy [treatment for iron overload]
  • neutropenia
  • bone marrow recipients
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6
Q

What is mech by with hyperglycemia DKA increase risk of mucormycosis?

A
  • have impaired phagocytic chemotaxis toward organisms
  • impaired killing by oxidative/non-oxidative mech
  • increased level of serum iron because iron released from binding proteins in acidosis
  • iron plays role in increasing virulence of the fungi
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7
Q

What is a mech by which mucormycosis can supply its own iron?

A
  • rhizopus species use deferoxamine [an iron chelator] as a siderophore to be able to make previously unavailable iron available to the fungus
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8
Q

What are the two common manifestations of mucormycosis? where else can it manifest?

A
  • rhinocerebral disease
  • primary cutaneous infection
  • can also manifest in lungs, GI, disseminated infection
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9
Q

What is path of primary cutaneous zygomycete infection? how is it transmitted? risk factors? symptoms?

A
  • due to direct innoculation
  • may follow surgery, burn wound, trauma, associated with non-sterile bandages
  • characterized by black, necrotic lesions
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10
Q

How do you treat zygomycete infections?

A
  • aggressive surgical debridement + adjunct therapy with amphotericin
  • posaconazole oral for prevention
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11
Q

What are properties of aspergillis?

A
  • septated hyphae with acute angle branching
  • ubiquitous spore-bearing fungus, septate hyphae, 45 degree branching
  • grows in air ducts, decaying wood, organic matter
  • culture shows fruiting head on lactophenol blue stain
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12
Q

Can voriconazole treat zygomycetes?

A

no! just aspergillus

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13
Q

Who is at risk for aspergillus

A
  • immunocompromised, recent transplant

- neutropenia

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14
Q

What is the most common invasive mold infection worldwide?

A

aspergillus

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15
Q

Where does aspergillus live in nature?

A
  • in air ducts, decaying wood, organic matter, house plants, soil
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16
Q

What are most common aspergillus species?

A
  • A. fumigatus [most common]
  • A. flavus
  • A. niger
  • A terreus
  • A nidulans
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17
Q

What are clinical manifestations of aspergillus?

A
  • allergic bronchopulmonary aspergillosis [ABPA] [wheezing, cough]
  • aspergilloma [fungus ball in lung, usually in pt who used to have TB]
  • invasive pulm and systemic disease in immunocompromised
  • primary cutaneous infections in immunocompromised
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18
Q

What makes aspergillus unique from zygomyctes?

A
  • thinner
  • more acute angle branching
  • contain cross walls/septa
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19
Q

What are signs of invasive pulmonary aspergillosis? who get it?

A
  • in people with depressed immune system
  • central area of necrosis surrounded by hemorrhage = nodule
  • mass of sepate with acute angle branching
  • hyphae within blood vessel see in silver stain –> thinner than zygo.
  • “coin” lesions = hemorrhage in lung
  • most infections associated with lung
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20
Q

What are signs of primary cutaneous aspergillosis? pathogenesis?

A
  • can be primary [from direct inoculation] or secondary [via dissemination from lung or other site]
  • associated with adhesive tape and arm boards
  • usually in pts with hematologic disease, neutropenia
  • signs: erythmatous macules, papules, plaques evolving to ulcerations with central necrotic eschars
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21
Q

How is asperigillosis transmistted?

A
  • via inhalation of conidia
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22
Q

What is pathogenesis of invasive aspergillosis infection and immune response?

A
  • conidia inhaled and lodge in lower resp
  • macrophages try to block conidia
  • conidia germinate into hyphae
  • neutrophils try to block
  • hyphae invade tissues
  • neutrophils try to block
  • hyphae invade blood + disseminate
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23
Q

What is treatment for aspergillus?

A
  • voriconazole [better side effect] or amphotericin for invasive disease
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24
Q

What determines survival of invasive aspergillus disese?

A

determined by immune recovery

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25
Q

How is pneumocystis jiroveci diagnosed?

A
  • cannot be grown in culture
  • diagnosed based on morphology or direct fluorescence antibody [DFA]
  • stain with silver stain to see cells
26
Q

what are signs of pneumocystis jiroveci pneumonia?

A
  • patchy alveolar infiltrates
  • filling of alveolar space with proteinacious material –> impaired gas exchange
  • get large cysts that appear on lungs that can sometimes rupture
27
Q

What is a possible severe complication of pneumocystis jiroveci?

A

pneumothorax

28
Q

How does pneumocytis replicate?

A
  • sexually or asexually
29
Q

What is treatment for pneumocystis?

A
  • trimethoprim-sulfamethoxazole [bactrim] at high dose [usually IV]
  • add steroids for pts with significant hypoxia
  • prophylaxis with TMP/SMX for pts with CD4 <200
30
Q

What are side effects of bactrim?

A
  • rash
  • renal failure
  • hyperkalemia
  • bone marrow toxicity
  • increased liver function test
31
Q

What are examples of common topical dermatophytes?

A
  • athletes foot
  • dandruff
  • ringworm
  • pytiriasis versicolor
32
Q

who gets pneumocystis?

A
  • mostly HIV

- also other immunocompromised [transplant], people with high doses of steroids

33
Q

What is tinea pedis?

A
  • topical dermatophyte = athlete’s foot, in warm wet sneaker

- causes pruritic infection in intertriginous infection

34
Q

How do you treat tinea pedis?

A
  • topical antifungals: miconazole, tolnaftate
35
Q

What are tinea cruris?

A
  • similar to athletes foot lesions but in groin = jock itch
36
Q

What is disease associated with trychophyton rubrum? how do you treat?

A
  • fungal onchomycosis = toenail fungus
  • difficult to treat with topical antifungals
  • sometimes use systemic terbinafine [lamisil]
37
Q

What is disease associated with tinea corporis?

A

= ringworm [a fungus not a worm]

38
Q

What are taenia?

A

taenia = tapeworms = cestodes –> acquired by eating undercooked parasitized meat [beef, pork, fish, etc]

39
Q

What causes ringworm?

A
  • tinea corporis

- also tricophyton species [verrucosum]

40
Q

What is pityriasis versicolor?

A
  • superficial dermatophyte

- infection characterized by hypo or hyperpigmnetation

41
Q

What causes pityriasis versicolor?

A

malassezia furfur

42
Q

How do you diagnose malassezia furfur?

A
  • diagnose of scraping stained with KOH shows both yeast and hyphal forms = spaghetti and meatballs
43
Q

How do you treat pityriasis versicolor?

A
  • topical antifungals: miconazole, tolnaftate
44
Q

How can you diagnose topical dermatophytes?

A
  • visualize hyphae by staining with KOH or calcafluor white
45
Q

What are subcutaneous fungal infections?

A
  • involve dermis and subcutaneous tissue
  • mostly in tropics
  • infection enters skin via local trauma
  • rarely disseminate but more at risk for immunosuppressed
46
Q

What is mycetoma “madura foot”?

A
  • fungi like madurella

- could also be caused by actinomyces

47
Q

What causes eumycetoma?

A

fungal agents –> madurella species [madurella mycetomatis, madurella grisea]

48
Q

What causes actinomycetoma?

A

actinomyces including nocardia

49
Q

What does eumycetoma mean?

A

fungal colony underneath surface of skin

50
Q

How do you treat madurella grisea?

A
  • treat with surgical removal, amputation
  • sometimes treat with posaconazole
  • poorly responsive to traditional antifungal therpay [itraconazole, amphotericin B]
51
Q

Who gets eumycetoma? how does it present?

A
  • slowly progressive subcutaneous infection
  • fungal granules = black with coarse texture
  • seen in farmers
52
Q

What is sporotrichosis associated with?

A

rose gardening, rose thorns

53
Q

What is pathogenesis of sporotrichosis?

A
  • prick finger with rose thorn

- get fungus infection there, spreads up arm lymphangitically

54
Q

What are signs of sporotrichosis?

A
  • characteristic lymphangitic spread of red rash up the arm
55
Q

What causes sporotrichosis?

A

sporothrix schenckii

56
Q

How do you treat sporothrix schenckii?

A
  • sporonox [itraconazole]
57
Q

What is exophiala jeanselmei? how does it present?

A
  • dematiaceous [pigmented] fungi
  • cause of phaeohyphomycosis
  • presents as solitary sometimes cystic subcutaneous nodule on distal extremity
58
Q

What are the three dematiaceous fungi?

A
  • exophiala jeanselmei
  • hoartaea werneckii
  • exophilaa spinifera
59
Q

What caused recent fungal meningitis outbreak?

A

exserohilum rostratum

60
Q

What are properties of Paecilomyces?

A
  • ubiquitous saprophytic organism

- example of non-pigemented fungi [hyalohyphomycoses]

61
Q

What disease is paecilomyces associated with?

A
  • sometimes recovered as contaminant in pulmonary specimens

- device infections and infections in immunocompromised hosts

Microbiology Part 2 (30 decks)

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