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Block 6 Week 5 > Opportunistic Mycoses-Kozel > Flashcards

Opportunistic Mycoses-Kozel Flashcards

1
Q

What are the opportunistc mycoses?

A
  • Candidiasis
  • Aspergillosis
  • Mucormycosis
  • Cryptococcosis
  • Pneumocystosis
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2
Q

What is the morphology of candida albicans and candida spp?

A

primarily yeasts; also pseudohyphae and true hyphae

form germ tubes

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3
Q

What are germ tubes?

A

hypha emerging from a yeast-like structure

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4
Q

What is commensalism?

A

an association between two organisms in which one benefits and the other derives neither benefit nor harm.

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5
Q

Where does candida albicans and candida spp. hang out?

A

skin-particularly health care workers
entire GI tract- mouth to rectum
femal genital tract

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6
Q

What are the species of candida spp? What is the most common?

A 
C. albicans (most common)
C. glabrata
C. parapsilosis
C. tropicalis
C. krusei
C. lusitaniae
C. guilliermondii
C. dublinensis
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7
Q

What is candidasis?

A

infection with candida, especially as causing oral or vaginal thrush.

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8
Q

Most infections of candidiasis are (Blank)

A

endogenous

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9
Q

How do you get canidiasis?

A

endogenously, normal commensal flora takes advantage of an opportunity to cause infection

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10
Q

What can candidiasis present as?

A
  • Mucus mebrane infection
  • Cutaneous candidiasis syndromes
  • Deep organ involvement
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11
Q

What are the mucous membrane infections that candidiasis causes?

A
  • Thrush
  • Candida esophagitis-often in AIDS
  • Vaginitis - 75% of normal women have at least one episode
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12
Q

What organ can be involved with candidiasis?

A 
CNS
Endocarditis
Pneumonia
Bone and Joint pain
Urinary tract
Abdominal
Hematogenous disseminated candidiasis (INVASIVE candidiasis)
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13
Q

What is a nosocomial infection

A

(of a disease) originating in a hospital.

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14
Q

What is the third most common blood stream infection?

A

invasive candidiasis (super expensive to cure)

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15
Q

What are the general risk factors for invasive candidiasis?

A 
hematologic malignancy
neutropenia
GI surgery
premature infants
patients older than 70 years
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16
Q

What are the specific risk factors for invasive candidiasis?

A

time spent in the ICU
central venous catheter
colonizaton at multiple sites
number of antibiotics given

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17
Q

How do you diagnose candidiasis?

A

Direct examination

Culture

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18
Q

How do you directly examine candidiasis to diagnose it?

A
  • Scrapings of mucosal or cutaneous lesions -KOH
  • Histopathology
  • Budding yeast-like forms and pseudohyphae
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19
Q

How do you test a culture of candidiasis?

A
  • take a sample (scrapings, blood (only 50% pos), tissue or sterile body fluids)
  • growth on mycologic media
  • selective chromogenic medium (CHROmagar Candida)
  • confirmation by germ tube formation
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20
Q

How do different candida spp appear on chromogenic medium?

A

different colors

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21
Q

How do you treat oral thrush caused by mucocutaneous candidiasis?

A
  • topical creams, lotions; nystatin or clotrimazole
  • oral systemic therapy: flucanole or other azoles
  • prophylactic fluconazole in AIDS
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22
Q

How do you treat esophagitis caused by mucocutaneous candidiasis?

A

oral system therapy: fluconazole

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23
Q

How do you treat uncomplicated vaginitis caused by mucocutaneous candidiasis?

A

over the counter topical azoles

oral azoles

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24
Q

How do you treat recurrent vaginitis caused by mucocutaneous candidiasis?

A
  • remove or treat causal factors, i.e HIV, uncontrolled diabetes, antibacterials, hormone replacement therapy
  • induction course of azole followed by long-term maintenance regimen
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25
Q

How do you prevent deep seated candidiasis?

A
  • avoid broad spectrum antibiotics
  • meticulous catheter care
  • rigorous infection control
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26
Q

How do you treat deep-seated candidiasis?

A

remove source of infection

  • remove or change vascular catheter
  • drain abscesses
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27
Q

What antifungal agents should you use on deep-seated candidiasis?

A

varies w/ site of infection and patient status i.e neutropenic vs. non-neutropenic

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28
Q

If deep seated candidiasis what polyene antifungals should you use?

A

amphotericin B or liposomal amphotericin B

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29
Q

If deep seated candidiasis what triazole antifungals should you use?

A

primarily fluconazole

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30
Q

If deep seated candidiasis what Echinocandin antifungals should you use?

A

caspofungin

31
Q

What is the morphology of Aspergillus spp?

A

branched septate hyphae

conidial heads with spheric conidia

32
Q

Where will you find aspergillus spp?

A

ubiquitous in air, soil, and decaying vegetation
Hospitals-air, water, potted plants
(CONSTANTLY being inhaled)

33
Q

WHat is the distribution of aspergillus spp?

A

worldwide distribution

34
Q

How many species of importance does aspergillus spp have?

A

19 disease producing species

35
Q

WHat is the most common invasive species of aspergillus spp?

A

A. fumigatus

36
Q

WHat are the top four most common invasive species of aspergillus spp?

A

A. fumigatus
A. flavus
A. niger
A. terreus

37
Q

Is aspergillus easy to treat?

A

no it is new and hard to treat

38
Q

What TH-2 response can aspergillosis give you?

A

allergic bronchopulmonary aspergillosis

39
Q

What is aspergilloma?

A

fungus balls of lungs

mass of hyphae in pre-existing cavity

40
Q

How can aspergillosis infection progress to an invasive syndrome?

A
  • begins in lungs following inhalation of conidia.

- Angioinvasive

41
Q

What is ingasive aspergillosis associated with?

A

immunosuppression

i.e. organ, stem cell or marrow transplants, neutropenia, corticosteroids or other immunosuppressive therapies

42
Q

What are clinical forms of aspergillosis?

A 
invasive pulmonary aspergillosis
disseminated infection (EXTREMELY HIGH MORTALITY)
43
Q

Aspergillosis is toxic, why?

A

aflatoxin

44
Q

Is aspergillosis super scary in transplants to get?

A

YES it kills a lot of people especially liver transplant patients

45
Q

How do you diagnose aspergilosis?

A

tissue biopsy
cultures
radiology

46
Q

If you take a tissue biopsy and look at the histopath what wil you see?

A

invasion with septate hyphae.

acute-angle branching

47
Q

What are the special stains you should you in diagnosis of aspergillosis?

A

Gomori methenamine silver, PAS

48
Q

If you take a tissue biopsy, is it easy to culture?

A

yyyeeeeaaaahhhhh

speciation requires skills though

49
Q

T or F

tissue biopsy sometimes too risky in immunosuppressed patients

A

T

50
Q

Are blood cultures for aspergillosis often positive?

A

no, actually it is rarely

51
Q

Cultures from a non-sterile site are (easy/difficult) to interpret

A

difficult

52
Q

When is radiology useful with aspergillosis?

A

in invasive pulmonary aspergillosis

53
Q

Why are biomarkers useful for aspergillosis?

A
  • to identify beta-glucan (nonspecific fungal marker)

- immunoassay for galctomannan in serum

54
Q

How do you prevent aspergillosis?

A
  • patient isolation, HEPA filters, positive pressure

- Pozaconazole prophylaxis for very high risk patients

55
Q

How do you treat aspergillosis?

A

voriconazole (primary therapy)

alternatives: AmB, triazoles, echinocandins

56
Q

What is the morphology of mucorales and mucormycosis?

A

Coenocytic hyphae-few septae, multinucleate

Saclike fruiting structure (sporangia) with internal spores (sporangiospores)

57
Q

Where can you find mucorales and mucormycosis?

A

ubquitous in evironment, particularly decaying organic substrates: bread, fruits, vegetable matter, soil

58
Q

Is infection with mucorales and mucormycosis prevalent?

A

no

59
Q

What are the important types of fungi in the Mucorales family?

A

Rhizopus (most prevalent; 47%)
Mucor
Cunninghamella
Absidia

60
Q

How do you get mucormycosis?

A

inhalation or cutanaeous or percutaneous inoculation of spores

61
Q

Is mucormycosis angioinvasive?

A

yes

62
Q

What are the risk factors for mucormycosis?

A
  • neutropenia
  • solid organ/hematopoietic stem cell transplant
  • diabetes or metabolic acidosis
  • deferoxamine (chelation) therapy to remove excess iron
63
Q

What are the clinical diseases associated with mucormycosis?

A

rhinocerebral-associated with diabetes
pulmonary infection
cutaneous
disseminated mucormycosis

64
Q

How do you diagnose mucormycosis?

A

Samples
Histopath
Culture
Biomarkers

65
Q

What samples do you want to get to diagnose mucormycosis?

A

Biopsy, swabs, etc.

Blood cultures rarely positive

66
Q

What should histopath show you in mucormycosis?

A

– broad (3 to 25 µm diameter), empty, thin-walled, mostly aseptate hyphae

67
Q

What will a culture of mucormycosis show you?

A
  • rapid growth on standard mycologic media

- speciation based on shape of the sporangium and the location of sporangiospores

68
Q

What will biomarkers test for mucormycosis show you?

A

tests for β-glucan or galactomannan are negative

69
Q

What is the treatment for mucormycosis?

A

AmB

reverse underlying condition, surgical resection

70
Q

Why does mucormycosis have such a poor prognosis?

A

Resistant to many antifungals: ketoconazole, fluconazole, voriconazole, flucytosine (5-FC), and the echinocandins

71
Q

The patient is a 43-year-old woman who became severely neutropenic during the course of chemotherapy for treatment of breast cancer. She developed cough, chest pain, shortness of breath and had a persistent fever despite conventional antibiotic therapy. Results of a lung biopsy are shown below. What is the diagnosis?

Pulmonary blastomycosis
Chronic pulmonary histoplasmosis
Pulmonary tuberculosis
Invasive pulmonary aspergillosis
Progressive pulmonary coccidioidomycosis
A

This is a case of invasive pulmonary aspergillosis. The micrograph shows branching, septate hyphae. Blastomycosis and histoplasmosis would show yeast cells in tissue. Pulmonary tuberculosis would show small bacilli. Coccidioidomycosis would show spherules with no hyphae

72
Q

The patient is a 28-year-old who presents with vaginitis that is accompanied by a thick, curdlike discharge. Physical exam showed edema and pruritis of the vulva. Microscopy showed epithelial cells and masses of hyphae. She was given a topical antifungal that is widely available over the counter. What is the mechanism of action of the antifungal?

Blocks ergosterol synthesis
Inhibits DNA and RNA synthesis
Inhibits squaline epoxidase
Inhibits folic acid synthesis
Inhibits glucan synthesis
A

This is a case of vaginal candidiasis. Topicals for treatment of candida vaginitis have an azole as their active ingredient. Azoles inhibit lanosterol demethylase to block ergosterol synthesis. The distractors describe respectively the modes of action of flucytosine, terbinafine, sulfonamides and the caspofungins.

73
Q

A 12-year-old girl received aggressive chemotherapy for acute lymphoblastic leukemia. Four weeks after initiation of therapy, she presented with signs, symptoms and radiological evidence of brain abscess. A craniotomy and biopsy were done. Histopathology showed the presence of broad, largely aseptate hyphae. Culture grew the organism shown below. What is the best antifungal for treatment of this infection?

Ketoconazole
Fluconazole
Caspofungin
Amphotericin B
Flucytosine
A

This is a case of cerebral mucormycosis. The image shows the sporangium and internal sporangiospores characteristic of the order Mucorales. The drug of choice for treatment of mucormycosis is amphotericin B. The Mucorales are intrinsically resistant to the other antifungals.

Block 6 Week 5 (10 decks)

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