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MICROM 460 > Mycology Lecture 4 > Flashcards

Mycology Lecture 4 Flashcards

1
Q

opportunistic mycoses have a ____ incidence in vulnerable patient populations.

A

high

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2
Q

T or F: Opportunistic mycoses are found globally.

A

true

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3
Q

risk of disease by opportunistic mycoses depends on two things - what are they?

A
  1. host immune defects

2. facilitating conditions

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4
Q

mortality rate with opportunistic mycoses is highly ______.

A

variable

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5
Q

since people who get infected with opportunistic mycoses often have an immune defect, then what is important in treatment?

A

return of the immune system

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6
Q

name some examples of facilitating conditions (3)

A
  • indwelling vascular catheters
  • surgical procedures
  • trauma to skin/mucosa
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7
Q

name some examples of things (like diseases or drugs) that lead to impaired immune defenses

A
  • neutropenia
  • impaired T cell function
  • HIV/AIDS
  • primary immunodeficiencies (chronic granulomatous disease)
  • corticosteroids
  • TNF blockers
  • alcoholism
  • diabetes
  • pregnancy
  • prematurity
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8
Q

name some examples of things that lead to impaired homeostasis

A
  • damage to mechanical barriers like the mucociliary escalator
  • iron overload states (allows for fungi to grow)
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9
Q

why is diabetes a risk factor for getting opportunistic fungal infections?

A

in patients w/ diabetes, glucose levels are increased and this allows fungi to feed

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10
Q

neutropenia typically occurs following a ____ _____ or ____ ______ transplant, or intensive ____________.

A

bone marrow OR stem cell,

chemotherapy

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11
Q

is candida an ascomycete or basidiomycete?

A

ascomycete

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12
Q

t or f: candida is part of the normal human flora, specifically in the skin and gut

A

true

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13
Q

candida is found everywhere, including in _____, _______, and _______.

A

soil, water, plants

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14
Q

what is the most common fungal opportunist?

A

candida

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15
Q

which fungi is a common cause of bloodstream infection in the US?

A

candida (4th most common)

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16
Q

is candida able to grow on catheters, foreign bodies, and artificial heart valves?

A

yes

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17
Q

more than ___ species of candida are thought to cause human disease

A

20

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18
Q

which species of candida is the most common cause of systemic candidiasis?

A

c. albicans

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19
Q

c. albicans is _______ to fluconazole

A

sensitive

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20
Q

c. glabrata has _______ _______ to fluconazole

A

inducible resistance (via efflux pump)

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21
Q

c. krusei is ________ _______ to fluconazole

A

intrinsically resistant

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22
Q

c. parapsilopsis is _______ to fluconazole

A

sensitive

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23
Q

this species of candida is not as frequent as other candida species, but we are seeing an increase in cases.

A

c. tropicalis

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24
Q

what species of candida is labeled as emerging?

A

c. auris

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25
Q

why is c. auris concerning? (2 reasons)

A
  • it has a difficult resistance pattern

- it has a higher morbidity/mortality rate

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26
Q

looking at local epidemiology of candida, c. ______ is the most common, followed by c. _________

A

albicans, glabrata

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27
Q

name a difference in structure between pseudohyphae and hyphae

A

pseudohyphae is pinched and balloons outward. the true hyphae is not pinched and has parallel sides of consistent diameter.

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28
Q

c. albicans can form a ____ _____, but other species most form ________.

A

true hyphae, pseudohyphae

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29
Q

name 3 virulence attributes that candida has

A
  1. adhesins
  2. biofilm production
  3. morphogenesis
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30
Q

an increase in ______, _____, or ______ can lead to increase in candida on your body.

A

warmth, moisture, nutrients

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31
Q

people with an imbalanced flora include (4)

A
  • infants
  • people who take antibiotics
  • pregnant women
  • diabetic patients
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32
Q

people with epithelial damage include those who have….(5 things)

A
  • trauma
  • friction
  • maceration
  • burns
  • cancer/chemotherapy (other infections)
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33
Q

_______ damage and an ______ in candida on your body leads to ________ candidiasis

A

epithelial, increase, superficial

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34
Q

where candida becomes systemic, it has a high affinity for the _____ and ___, but it can also travel to the _____/_____, _____, and _____

A

blood, eyes, liver/spleen, brain, heart

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35
Q

_______ is very rare with candida. it does not end up in the ______ or _______ tract

A

pneumonia, lung, urinary tract

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36
Q

candida is associated with superficial/mucocutaneous infections, such as _______, _______, __________, and ________.

A

onychomycosis, vulvovaginitis, oropharyngeal, esophageal

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37
Q

the major portal of infection with candida is the ______ tract and ______.

A

GI tract, catheters

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38
Q

what is the most common species of candida involved in causing oropharyngeal candidiasis (thrush)?

A

c. albicans

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39
Q

describe the appearance of oropharyngeal candidiasis

A

white psuedomembranous plaque, red inflamed lesions

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40
Q

thrush is usually diagnosed based on _____, but a ____ test can be conducted as well

A

appearance, KOH

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41
Q

what are the risks for getting thrush? (3)

A
  • AIDS
  • antibiotic use
  • steroid inhalers
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42
Q

what is the treatment for thrush?

A

mouthwash/lozenges (first line) or fluconazole

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43
Q

similar to thrush, c. _____ is the most common cause of esophageal candidiasis

A

albicans

44
Q

candida can become present in the esophagus when it goes beyond the mouth. it is ____ to treat and is linked to ___ and difficulty _______.

A

harder, pain, swallowing

45
Q

esophageal candidiasis is typically seen in ____ and ______ patients.

A

AIDS, cancer

46
Q

what is the treatment for esophageal candidiasis?

A

fluconazole, echinocandin if resistant species

47
Q

certain occupations are at more risk for getting onychomycosis. what occupations are those? (3)

A

dishwashers, bartenders, fruit pickers

48
Q

candida is isolated from the genital tract of __ - ___ % of asymptomatic women

A

20-50%

49
Q

culture for candida vulvovaginitis is not _____ because many people are ______.

A

specific, colonized

50
Q

name risk factors for candida vulvovaginitis

A
  • diabetes
  • corticosteroids
  • antibiotics
  • pregnancy
  • AIDS
  • oral contraceptive
51
Q

what is the predominant species that leads to vulvovaginal candidiasis?

A

c. albicans

52
Q

what encourages growth of candida in the vagina? (3)

A
  • estrogen therapy (high levels increase vaginal glycogen content which is a carbon source for candida)
  • pregnancy
  • antibiotic use (vaginal bacteria decrease, fungi can flourish)
53
Q

how is vulvovaginal candidiasis diagnosed?

A
  • appearance

- lab confirmation using KOH test

54
Q

what is the treatment for VVC?

A
  • azoles and polyenes

- fluconazole for 1-2 doses

55
Q

______ colonization of candida with superficial breakdown or massive trauma/deep burns as well as _______ defenses can lead to ______ candidiasis

A

high, immune, systemic

56
Q

what is candida fungemia?

A

blood infection where candida has invaded the blood

57
Q

what is the mortality rate for candida fungemia?

A

30-40%

58
Q

how is candida fungemia diagnosed? (4)

A
  • blood culture
  • skin biopsy
  • tissue biopsy
  • blood antigen test (B-D glucan)
59
Q

what examination should patients with candida fungemia get?

A

eye examination

60
Q

t or f: when a patient has candida fungemia, their heart valves is commonly infected.

A

false - this is rare

61
Q

how long does candida typically take to grow? how many days to identify?

A

1-3 days to grow

1-2 days for ID

62
Q

what is a faster method to identify candida?

A

MALDI-TOF and PNA-FISH

63
Q

name non-culture methods for diagnosing candida (4)

A
  1. antigen assays (B-D-glucan)
  2. PCR (increasingly being used)
  3. T2Candida (3-5 hrs from blood specimen)
  4. serology (not useful)
64
Q

candida can also be diagnosed using a ___ test. it appears as a gram ______

A

KOH, positive

65
Q

looking at candida on plates, what does c. albicans look like?

A

whitish colored colonies with feet

66
Q

what is CHROMagar candida?

A

it is a differential culture medium that identifies species of candida based on change in their color

67
Q

the _____ _____ test is a screening procedure which is used for the ID and differentiation of c. albicans from other yeasts

A

germ tube

68
Q

t of r: beta-d-glucan is unique and specific to c. albicans

A

FALSE - it is a cell wall component in many fungi

69
Q

what is the sensitivity of the beta-d-glucan test for c. albicans?

A

80-90%

70
Q

the beta-d-glucan test typically comes out negative for ______ and ______

A

cocci & mucormycosis

71
Q

describe how t2 candida works

A
  1. breaks up the yeast
  2. amplifies the DNA
  3. detects yeast DNA by using magnetic resonance technology
72
Q

how specific is t2 candida?

A

99% specific

73
Q

since there is variable levels of resistance depending on the candida species, it has been recommended to start with _______

A

echinocandins

74
Q

t or f: c. auris is typically misidentified

A

true

75
Q

c. auris is ___ resistant to fluconazole, and __ resistant to amp B

A

90%, 30%

76
Q

c. auris can persist on _____ for _____. it is associated with outbreaks in ________ facilities.

A

surfaces, weeks, healthcare

77
Q

t or f: patients with c. auris do not have to placed into contact rooms because it can’t spread person to person

A

false

78
Q

what is unique about the appearance of cryptococcus?

A

thick capsule

79
Q

unlike candida, cryptococcus infection occurs via ______

A

inhalation

80
Q

cryptococcus neoformans is an ______ pathogen, while cryptococcus gattii is a ______ pathogen

A

opportunistic, primary

81
Q

what is cryptococcus gattii associated with? where is it found?

A

eucalyptus tree and koala bears, found in Australia, NZ, and Eastern Vancouver island

82
Q

is cryptococcus an ascomycete or basidiomycete?

A

basidiomycete

83
Q

is cryptococcus intracellular or extracellular?

A

extracellular

84
Q

what are the two mating types of cryptococcus?

A

a and alpha

85
Q

which one is more virulent: a or alpha?

A

alpha - also more common in clinical infections

86
Q

what are the 3 main virulence attributes of crypto?

A
  1. polysaccharide capsule
  2. melanin production
  3. mating type (a or alpha)
87
Q

C. neoformans is _____ encapsulated in the environment. it is _____ in size, which allows it to sneak into the alveoli of our lungs.

A

weakly, small

88
Q

C. neoformans becomes _______ in the lungs, where the capsule becomes ______

A

rehydrated, thicker

89
Q

the thick capsule that crypto has once in the lungs is beneficial because …..

A

it allows it to hide from our immune system (protects phagocytosis, barrier for complement)

90
Q

if crypto has a mutation that renders its capsule biosynthesis pathway defective, then it becomes ______

A

avirulent

91
Q

how does high salt affect capsule size? low glucose? low iron? physiological CO2?

A

decreases, increases, increases, increases

92
Q

what is the function of melanin?

A

protects fungal cells from respiratory burst

93
Q

t or f: crypto mutants that cannot produce melanin are completely avirulent

A

false - it’s reduced

94
Q

localized pulmonary crypto is usually ________ and can be left untreated (c. _____)

A

self-limiting, c. neoformans

95
Q

invasive pulmonary crypto can lead to _________, and it is rare except in patients who are _________

A

dissemination, immunocompromised

96
Q

crypto meningitis is characterized by increased _________ _____

A

intracranial pressure

97
Q

what treatment is used for crypto meningitis?

A

lumbar puncture, or surgical drain to remove CSF

98
Q

what is treatment for crypto meningitis?

A

amp B and 5FC then fluconazole

99
Q

in an unhealthy host, what antifungal should be used for crypto pneumonia? what about for a normal host?

A

fluconazole, in normal host no treatment required

100
Q

what is the biggest risk factor for c. neoformans meningitis?

A

AIDS (15% of AIDS related deaths globally)

101
Q

where are most cases of c. neoformans localized?

A

sub-saharan africa

102
Q

for crypto meningitis in resource limiting countries, there is a ___ morality rate if getting HIV care, but ____ if not

A

70%, 100%

103
Q

for crypto meningitis in north america, there is a ___ morality rate if getting HIV case, but ___ if not

A

20%, 30%

104
Q

how is crypto diagnosed? (4)

A
  • crypto antigen (CrAg): using serum (ie blood) or CSF
  • culture
  • histology (capsule stains red with mucicarmine stain, black with silver stain)
  • PCR
105
Q

how is c. neoformans told apart from c. gattii?

A

PCR

106
Q

what does crypto look like?

A

narrow based budding yeast

107
Q

what diagnostic test is done for crypto out of historical interest?

A

india ink prep CSF (capsule excludes ink)

MICROM 460 (20 decks)

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