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Block 6 Week 5 > Kozel: Opportunistic Mycoses > Flashcards

Kozel: Opportunistic Mycoses Flashcards

1
Q

List 5 opportunistic mycoses

A 
Candidiasis
Cryptococcosis
Aspergillosis
Mucormycosis
Pneumocystosis
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2
Q

Where are Candida albicans and Candida spp. normally found?

A

in the skin - particularly in health care workers
in the GI tract from the mouth to the rectum
in the female GU tract

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3
Q

What is the most common species of Candida?

A

C. albicans

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4
Q

What is the morphology of Candida albicans and Candida spp?

A

primarily yeasts
true hyphae
pseudohyphae

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5
Q

What do Candida spp form?

A

germ tubes *hypha emerging from a yeast-like structure

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6
Q

Most infections with Candida are endogenous. What does this mean?

A

normal commensal flora takes advantage of an opportunity to cause infection

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7
Q

What does Candidiasis cause at mucous membranes?

A

thrush
candida esophagitis *often in AIDS
vaginitis

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8
Q

What % of normal women have at least one episode of vaginitis causes by Candida?

A

75%

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9
Q

What organs/organ systems can Candida affect?

A 
CNS
pneumonia - lungs
bones and joints
endocarditis
urinary tract
abdominal
hematogenous disseminated candidiasis - in the blood
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10
Q

What type of infection does candidiasis cause?

A

major nosocomial infection

**3rd most common blood stream infection

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11
Q

What are the general risk factors for invasive candidiasis?

A 
hematologic cancer
neutropenia
GI surgery
premature infants
patients older than 70
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12
Q

What are some special risk factors for invasive candidiasis?

A

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

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13
Q

How would you diagnose candidiasis?

A
  1. scrape mucosal and cutaneous lesions and use KOH to see if yeast is present
  2. histopathology
  3. budding yeast-like forms and pseudohyphae
  4. look for germ tube formation

In all cases, look for budding yeast and pseudohyphae

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14
Q

What are three sources of tissue that you could culture to look for candida?

A
  1. scrapings from lesions
  2. blood *only 50% positive
  3. tissue or normally sterile body fluids
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15
Q

Candida can grow on standard mycologic media. What other medium might you use?

A

selective chromogenic medium

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16
Q

How can you CONFIRM a diagnosis of Candida?

A

germ tube formation - production of germ tubes when grown on serum

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17
Q

What is used to treat oral thrush caused by candida?

A

topical creams and lotions: nystatin or clotrimazole (azole)
oral systemic therapy: fluconazole or other azoles
prophylactic fluconazole in AIDS

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18
Q

What is used to treat esophagitis caused by candida?

A

oral systemic therapy: fluconazole

**topical therapy usu fails

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19
Q

What can be used to treat uncomplicated Candida vaginitis? What about recurrent Candida vaginitis?

A

over the counter topical azoles/oral azoles;

remove or treat causal factor - or induce course of azole followed by long-term maintenance regimen

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20
Q

How can you avoid cadidiasis?

A

avoid broad spectrum antibiotics!!
be cautious with catheter care
infection control

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21
Q

What are some ways in which you could remove the source of infection for candida?

A

remove or change the catheter

drain abscesses

22
Q

List three antifungal agents used for candida

A

Polyene **AmB (but watch out for nephrotoxicity)
Triazole **esp fluconazole
Echinocandin

23
Q

Where is Aspergillus spp. found?

A

everywhere! in air, soil, decaying vegetation

hospitals - air, water, potted plants

24
Q

What is the morphology of Aspergillus spp? What does it look like?

A

branched septate hyphae;

conidial heads with spheric conidia

25
Q

What are two diseases caused by Aspergillus?

A

allergic bronchopulmonary aspergillosis - type 2 reaction

aspergilloma - balls of fungus in the lungs

26
Q

How do invasive syndromes begin with Aspergillus? What are they syndromes associated with?

A

inhalation of conidia (spores) into lungs; angioinvase (can get into blood vessels and disseminate); associated with immunosuppression - organ/stem cell transplants, neutropenia, corticosteroids or other immunosuppressive therapies

27
Q

What toxin does Aspergillus produce?

A

aflatoxin

28
Q

Invasive aspergillosis is very common after (blank)

A

transplantation

29
Q

What do you look for to diagnose Aspergillosis?

A

look for invasion of hyphae - septate hyphae with acute-angle branching

30
Q

What else could you do to diagnose aspergillosis?

A

tissue biopsy - can’t use blood culture
**sometimes too risky in immunosuppressed patients
radiology for invasive pulmonary aspergillosis
biomarkers

31
Q

What are some biomarkers you would look for in aspergillosis?

A

beta-glucan - non-specific fungal marker

galactomannan in serum

32
Q

How can you prevent aspergillosis?

A

patient isolation
HEPA filters
positive pressure
pozaconazole prophylaxis for very high risk patients

33
Q

What is the primary drug used for treatment of aspergillosis?

A

voriconazole (triazole - blocks ergosterol synthesis)

34
Q

Where would you find mucorales and mucormycosis?

A

in the environment - particularly decaying bread, fruit, vegetable matter, soil

35
Q

What is the morphology of mucorales and mucormycosis?

A

coenocytic hyphae - with few septae - multinucleate

saclike fruiting structure with internal spores (sporangium with internal sporangiospores)

36
Q

What is the most common genera of mucorales that causes disease?

A

Rhizopus

37
Q

How do you get infected with mucormycosis?

A

inhalation of spores

38
Q

What does mucormycosis do to blood vessel walls?

A

causes necrosis - angioinvasive (invades blood vessels)

39
Q

What are some risk factors for infection by mucormycosis?

A

neutropenia
transplants (immunocompromised)
diabetes or any metabolic acidosis
deferoxamine (chelation) therapy to remove toxic amounts of iron (fungi use deferoxamine)

40
Q

What are 4 diseases that mucormycosis might cause?

A
  1. rhinocereberal (assoc. w diabetes mellitus)
  2. pulmonary infection
  3. cutaneous infection
  4. disseminated infection
41
Q

How would you diagnose mucormycosis?

A

biopsy, swabs, culture etc

in histopath, look for broad, empty, thin-walled mostly aseptate hyphae (coenocytic - no septal divisions)

42
Q

What biomarkers would you want to be NEGATIVE if you were looking to confirm a diagnosis of mucormycosis?

A

Beta-glucan and galactomannan

**these are positive for aspergillosis, but DON’T WORK FOR THIS ONE

43
Q

What is the overall drug of choice for mucormycosis?

A

Amphotericin B

**azoles don’t work

44
Q

What is the problem with mucormycosis? So what can be done?

A

resistance to many antifungals (azoles, flucytosine, echinocandins) - so reverse underlying condition, maybe via surgical resection

**overall, poor prognosis

45
Q

What would you look for in a slide of invasive pulmonary aspergillosis?

A

BRANCHING, SEPTATE HYPHAE

46
Q

What is the morphology of Cryptococcus neoformans?

A

encapsulated yeast

47
Q

Where is Crytococcus neoformans found?

A

in PIGEONS and trees

48
Q

What do you look for in the immunoassay for Cryptococcus neoformans?

A

capsular antigen

**use a drop of blood

49
Q

What are some diseases caused by Cryptococcus neoformans?

A

pulmonary cryptoccosis
crytococcal meningitis
opportunistic - AIDS and other immunosuppression

**kills tons of people in Africa :(

50
Q

What are the two forms of pneumocystis jirovecii?

A

tropic, sporocyst and cyst forms

**cysts are empty, collapsed balls

51
Q

What is unique about the life cycle of pneumocystis jirovecii?

A

sexual AND asexual life cycle

human is the reservoir

52
Q

What diseases are caused by Pneumocystis jirovecii?

A

likely infects most normal humans
esp those with AIDS, immunosuppression, infants
causes interstitial plasma cell pneumonitis

Block 6 Week 5 (11 decks)

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