Mycology Lecture 4 Flashcards
opportunistic mycoses have a ____ incidence in vulnerable patient populations.
high
T or F: Opportunistic mycoses are found globally.
true
risk of disease by opportunistic mycoses depends on two things - what are they?
- host immune defects
2. facilitating conditions
mortality rate with opportunistic mycoses is highly ______.
variable
since people who get infected with opportunistic mycoses often have an immune defect, then what is important in treatment?
return of the immune system
name some examples of facilitating conditions (3)
- indwelling vascular catheters
- surgical procedures
- trauma to skin/mucosa
name some examples of things (like diseases or drugs) that lead to impaired immune defenses
- neutropenia
- impaired T cell function
- HIV/AIDS
- primary immunodeficiencies (chronic granulomatous disease)
- corticosteroids
- TNF blockers
- alcoholism
- diabetes
- pregnancy
- prematurity
name some examples of things that lead to impaired homeostasis
- damage to mechanical barriers like the mucociliary escalator
- iron overload states (allows for fungi to grow)
why is diabetes a risk factor for getting opportunistic fungal infections?
in patients w/ diabetes, glucose levels are increased and this allows fungi to feed
neutropenia typically occurs following a ____ _____ or ____ ______ transplant, or intensive ____________.
bone marrow OR stem cell,
chemotherapy
is candida an ascomycete or basidiomycete?
ascomycete
t or f: candida is part of the normal human flora, specifically in the skin and gut
true
candida is found everywhere, including in _____, _______, and _______.
soil, water, plants
what is the most common fungal opportunist?
candida
which fungi is a common cause of bloodstream infection in the US?
candida (4th most common)
is candida able to grow on catheters, foreign bodies, and artificial heart valves?
yes
more than ___ species of candida are thought to cause human disease
20
which species of candida is the most common cause of systemic candidiasis?
c. albicans
c. albicans is _______ to fluconazole
sensitive
c. glabrata has _______ _______ to fluconazole
inducible resistance (via efflux pump)
c. krusei is ________ _______ to fluconazole
intrinsically resistant
c. parapsilopsis is _______ to fluconazole
sensitive
this species of candida is not as frequent as other candida species, but we are seeing an increase in cases.
c. tropicalis
what species of candida is labeled as emerging?
c. auris
why is c. auris concerning? (2 reasons)
- it has a difficult resistance pattern
- it has a higher morbidity/mortality rate
looking at local epidemiology of candida, c. ______ is the most common, followed by c. _________
albicans, glabrata
name a difference in structure between pseudohyphae and hyphae
pseudohyphae is pinched and balloons outward. the true hyphae is not pinched and has parallel sides of consistent diameter.
c. albicans can form a ____ _____, but other species most form ________.
true hyphae, pseudohyphae
name 3 virulence attributes that candida has
- adhesins
- biofilm production
- morphogenesis
an increase in ______, _____, or ______ can lead to increase in candida on your body.
warmth, moisture, nutrients
people with an imbalanced flora include (4)
- infants
- people who take antibiotics
- pregnant women
- diabetic patients
people with epithelial damage include those who have….(5 things)
- trauma
- friction
- maceration
- burns
- cancer/chemotherapy (other infections)
_______ damage and an ______ in candida on your body leads to ________ candidiasis
epithelial, increase, superficial
where candida becomes systemic, it has a high affinity for the _____ and ___, but it can also travel to the _____/_____, _____, and _____
blood, eyes, liver/spleen, brain, heart
_______ is very rare with candida. it does not end up in the ______ or _______ tract
pneumonia, lung, urinary tract
candida is associated with superficial/mucocutaneous infections, such as _______, _______, __________, and ________.
onychomycosis, vulvovaginitis, oropharyngeal, esophageal
the major portal of infection with candida is the ______ tract and ______.
GI tract, catheters
what is the most common species of candida involved in causing oropharyngeal candidiasis (thrush)?
c. albicans
describe the appearance of oropharyngeal candidiasis
white psuedomembranous plaque, red inflamed lesions
thrush is usually diagnosed based on _____, but a ____ test can be conducted as well
appearance, KOH
what are the risks for getting thrush? (3)
- AIDS
- antibiotic use
- steroid inhalers
what is the treatment for thrush?
mouthwash/lozenges (first line) or fluconazole
similar to thrush, c. _____ is the most common cause of esophageal candidiasis
albicans
candida can become present in the esophagus when it goes beyond the mouth. it is ____ to treat and is linked to ___ and difficulty _______.
harder, pain, swallowing
esophageal candidiasis is typically seen in ____ and ______ patients.
AIDS, cancer
what is the treatment for esophageal candidiasis?
fluconazole, echinocandin if resistant species
certain occupations are at more risk for getting onychomycosis. what occupations are those? (3)
dishwashers, bartenders, fruit pickers
candida is isolated from the genital tract of __ - ___ % of asymptomatic women
20-50%
culture for candida vulvovaginitis is not _____ because many people are ______.
specific, colonized
name risk factors for candida vulvovaginitis
- diabetes
- corticosteroids
- antibiotics
- pregnancy
- AIDS
- oral contraceptive
what is the predominant species that leads to vulvovaginal candidiasis?
c. albicans
what encourages growth of candida in the vagina? (3)
- estrogen therapy (high levels increase vaginal glycogen content which is a carbon source for candida)
- pregnancy
- antibiotic use (vaginal bacteria decrease, fungi can flourish)
how is vulvovaginal candidiasis diagnosed?
- appearance
- lab confirmation using KOH test
what is the treatment for VVC?
- azoles and polyenes
- fluconazole for 1-2 doses
______ colonization of candida with superficial breakdown or massive trauma/deep burns as well as _______ defenses can lead to ______ candidiasis
high, immune, systemic
what is candida fungemia?
blood infection where candida has invaded the blood
what is the mortality rate for candida fungemia?
30-40%
how is candida fungemia diagnosed? (4)
- blood culture
- skin biopsy
- tissue biopsy
- blood antigen test (B-D glucan)
what examination should patients with candida fungemia get?
eye examination
t or f: when a patient has candida fungemia, their heart valves is commonly infected.
false - this is rare
how long does candida typically take to grow? how many days to identify?
1-3 days to grow
1-2 days for ID
what is a faster method to identify candida?
MALDI-TOF and PNA-FISH
name non-culture methods for diagnosing candida (4)
- antigen assays (B-D-glucan)
- PCR (increasingly being used)
- T2Candida (3-5 hrs from blood specimen)
- serology (not useful)
candida can also be diagnosed using a ___ test. it appears as a gram ______
KOH, positive
looking at candida on plates, what does c. albicans look like?
whitish colored colonies with feet
what is CHROMagar candida?
it is a differential culture medium that identifies species of candida based on change in their color
the _____ _____ test is a screening procedure which is used for the ID and differentiation of c. albicans from other yeasts
germ tube
t of r: beta-d-glucan is unique and specific to c. albicans
FALSE - it is a cell wall component in many fungi
what is the sensitivity of the beta-d-glucan test for c. albicans?
80-90%
the beta-d-glucan test typically comes out negative for ______ and ______
cocci & mucormycosis
describe how t2 candida works
- breaks up the yeast
- amplifies the DNA
- detects yeast DNA by using magnetic resonance technology
how specific is t2 candida?
99% specific
since there is variable levels of resistance depending on the candida species, it has been recommended to start with _______
echinocandins
t or f: c. auris is typically misidentified
true
c. auris is ___ resistant to fluconazole, and __ resistant to amp B
90%, 30%
c. auris can persist on _____ for _____. it is associated with outbreaks in ________ facilities.
surfaces, weeks, healthcare
t or f: patients with c. auris do not have to placed into contact rooms because it can’t spread person to person
false
what is unique about the appearance of cryptococcus?
thick capsule
unlike candida, cryptococcus infection occurs via ______
inhalation
cryptococcus neoformans is an ______ pathogen, while cryptococcus gattii is a ______ pathogen
opportunistic, primary
what is cryptococcus gattii associated with? where is it found?
eucalyptus tree and koala bears, found in Australia, NZ, and Eastern Vancouver island
is cryptococcus an ascomycete or basidiomycete?
basidiomycete
is cryptococcus intracellular or extracellular?
extracellular
what are the two mating types of cryptococcus?
a and alpha
which one is more virulent: a or alpha?
alpha - also more common in clinical infections
what are the 3 main virulence attributes of crypto?
- polysaccharide capsule
- melanin production
- mating type (a or alpha)
C. neoformans is _____ encapsulated in the environment. it is _____ in size, which allows it to sneak into the alveoli of our lungs.
weakly, small
C. neoformans becomes _______ in the lungs, where the capsule becomes ______
rehydrated, thicker
the thick capsule that crypto has once in the lungs is beneficial because …..
it allows it to hide from our immune system (protects phagocytosis, barrier for complement)
if crypto has a mutation that renders its capsule biosynthesis pathway defective, then it becomes ______
avirulent
how does high salt affect capsule size? low glucose? low iron? physiological CO2?
decreases, increases, increases, increases
what is the function of melanin?
protects fungal cells from respiratory burst
t or f: crypto mutants that cannot produce melanin are completely avirulent
false - it’s reduced
localized pulmonary crypto is usually ________ and can be left untreated (c. _____)
self-limiting, c. neoformans
invasive pulmonary crypto can lead to _________, and it is rare except in patients who are _________
dissemination, immunocompromised
crypto meningitis is characterized by increased _________ _____
intracranial pressure
what treatment is used for crypto meningitis?
lumbar puncture, or surgical drain to remove CSF
what is treatment for crypto meningitis?
amp B and 5FC then fluconazole
in an unhealthy host, what antifungal should be used for crypto pneumonia? what about for a normal host?
fluconazole, in normal host no treatment required
what is the biggest risk factor for c. neoformans meningitis?
AIDS (15% of AIDS related deaths globally)
where are most cases of c. neoformans localized?
sub-saharan africa
for crypto meningitis in resource limiting countries, there is a ___ morality rate if getting HIV care, but ____ if not
70%, 100%
for crypto meningitis in north america, there is a ___ morality rate if getting HIV case, but ___ if not
20%, 30%
how is crypto diagnosed? (4)
- crypto antigen (CrAg): using serum (ie blood) or CSF
- culture
- histology (capsule stains red with mucicarmine stain, black with silver stain)
- PCR
how is c. neoformans told apart from c. gattii?
PCR
what does crypto look like?
narrow based budding yeast
what diagnostic test is done for crypto out of historical interest?
india ink prep CSF (capsule excludes ink)
