Opportunistic Fungi Flashcards
(166 cards)
1
Q
are fungi motile?
A
no
2
Q
fungi: prokaryotic or eukaryotic?
A
eukaryotic
3
Q
why do antifungals have significant toxicity?
A
cross-reactivity with mammalian compounds/enzymes
4
Q
what distinguishes fungi from prokaryotes?
A
membrane-bound nucleus and organelles
5
Q
DNA morphology?
A
multiple linear chromosomes
6
Q
fungi membranes not composed of cholesterol but instead…
A
ergosterol
7
Q
drug that binds to ergosterol
A
amphotericin B
8
Q
drug class that interferes with ergosterol biosynthesis
A
azoles
9
Q
fungi cell wall components (not found in mammals)
A
chitin
B-glucan
mannoproteins
10
Q
drugs that inhibit B-glucan synthase
A
echinocandins
11
Q
two fungi recognized as part of the normal human microbiota
A
C. albicans
M. furfur
12
Q
fungal energy source
A
heterotrophs –> organic material
NOT photosynthetic
absorptive, NOT phagotrophic
13
Q
drugs that cross-react with P450 enzymes
A
azoles
14
Q
fungi v. bacteria distinction: diaminopimelate, which one has it in their cell wall?
A
NO DAP in fungi
15
Q
term for organism that lives on dead/decaying botanic matter
A
saprobe
16
Q
a fungi that exists only as yeast
A
Cryptococcus neoformans
17
Q
a DIMORPHIC fungus who’s yeast morphotype is the pathogenic, invasive form? mold?
A
Yeast: Histoplasma capsulatum
Mold: Candida albicans
18
Q
which morphology grows by apical extension?
A
molds
19
Q
unicellular oval structure that divides by budding or fission
A
yeast
20
Q
a pathogenic fungus that exists only as a mold
A
Aspergillus
21
Q
hyphae, mycelia
A
molds
22
Q
both yeast/mold forms are invasive
A
candida
23
Q
a form of yeast growth where cells remain attached and elongate
A
pseudohyphae
24
Q
conversion to the host-adapted form is essential for pathogenesis in humans - especially systemic infections
A
dimorphism
25
dimorphic fungi (MSCHBC)
```
Malassezia (superficial)
Sporothrix (subQ)
Candida (opportunisitc)
Histo (systemic)
Blasto (systemic)
Coccidio (systemic)
```
26
Yeast fungi ONLY (2C)
```
Cryptococcus (opportunistic)
Candida glabrata (opportunistic)
```
27
Mold fungi ONLY (ADZ)
Aspergillus (opportunistic)
Dermatophytes (cutaneous)
Zygomycetes (subQ)
28
fusion of 2 gametangia --> zygote
zygomycetes
29
2 haploid nuclei fuse to form diploid --> meiosis in a sac "ASCUS" to form haploid
Ascomycetes
30
like asco but sac is called "BASIDIUM" --> haploid progeny mature on outer surface of sac (e.g.?)
Basidiomycetes
| Cryptococcus
31
no sexual stage identified for these fungi
deuteromycetes
32
allergy
Type I, IgE-mediated
exposure via inhalation/ingestion/contact
re-exposure --enhanced rxn
morbidity via host response
33
major atmospheric fungi causing hypersensitivity (ACA)
Alternaria
Cladosporium
Aspergillus
34
cheese washer's lung
Penicillium
35
paprika splitter's lung
Mucor stolonifer
36
ingestion of seeds/nuts leading to hepatotoxicity (acute) and liver cancer (chronic)
aflatoxins from Aspergillus (most potent naturally occurring toxin)
37
ingestion of grains and breads leading to vasoconstriction, peripheral necrosis, gangrene
ergot alkaloids from Claviceps purpurea
38
grains and breads causing cytotoxic/systemic effects
trichothecenes from Fusarium
39
building materials (esp. damaged by water)
trichothecenes from Stachybotrys
40
superficial S.C. or cuticle infection e.g.
Malassezia
41
epidermis, finger/toe nails, hairs (dermatophytes) (TME)
Trichophyton
Microsporum
Epidermophyton
42
dermis, subQ, fascia, bone
fungi that cause sporotrichosis and zygomycosis
43
Fungal entry via resp tract --> hematogenous/lymph spread or direct extension (the big 3)
Systemic (deep)
Histo/Blasto/Coccidio
can cause disease in the immunocompetent
44
fungal entry via wounds/burns, or immunodeficiencies (CCAP)
Crypto
Candida
Aspergillus
Pneumocystis jiroveci
45
risk groups for immunodeficiency
cancer/AIDS/transplant
young/elderly
hospitalized
prolonged survival of the severely ill
46
Containment of fungi requires?
antigen-specific CD4 T-cells
| activate MP's via IFN-y stimulation
47
CMI or humoral, which is of primary importance in defending fungi?
CMI
48
for which fungi are neutrophils critical for defense?
Aspergillus
| neutropenic pts, pts on chemo --> aspergillosis
49
this infection generally does not have sx, immune response, or physical discomfort
superficial mycoses
50
M. furfur
inhabits skin
| lipophilic, dimorphic
51
disseminated disease in infants receiving TPN
M. furfur
52
dandruff, cradle cap, seborrheic dermatitis
M. furfur
| can be early sign in HIV/AIDS pts
53
pathogenic form of M. furfur
HYPHAL (yeast is commensal)
54
asymptomatic disorder of host melanocytes
tinea versicolor
55
big 3 TME for cutaneous mycoses
Trichophyton
Microsporum
Epidermophyton
56
ectothrix/endothrix
growth w/in and outside hair shaft
57
paronychomycosis
fungal infection of nail beds
elderly
systemic abx
58
very contagious and transmittable infection
tinea
59
diagnostic methods for fungi
KOH --> lesion border
Wood's lamp --> fluorescence of cell wall
Culture for DEFINITIVE DX (rarely used)
60
infection while working with potting soil, sphagnum moss, pricked by a rose thorn
sporotrichosis
sporothrix schenkii
"gardener's disease"
61
Sporothrix schenkii
dimorphic
MOLD in env
yeast in tissues at 37C
62
small, hard, painless nodule that enlarges to a fluctuant mass that eventually ulcerates; may progress along lymphatics but rarely spreads beyond regional lymphatics
Lymphocutaneous sporotrichosis
63
inhalation of spores; may resemble TB
Pulmonary sporotrichosis
64
Zygomycosis fungi (RAM)
```
Rhizopus
Absidia
Mucor
Rapidly invasive (2-7d)
All types of presentations (cut, subQ, dissem, etc.)
```
65
common initial sites of zygomycosis infection
lungs/nasal sinuses
| burn/trauma pts also susceptible on skin
66
life-threatening, fulminant infection seen in ACIDOTIC individuals (poorly controlled DM) --> DKA
also in neutropenic pts or pts receiving IRON chelation therapy
Rhinocerebral zygomycosis
67
the 5 fungi of fragility (opportunism only)
Crypto
Candida albicans/other spp
Aspergillus
Pneumocystis j
68
brudzinski's / kerning's signs indicate?
meningeal inflammation
69
encapsulated budding yeasts on INDIA INK
Cryptococcus neo
70
big immune defects (CMI and innate)
innate: neutrophils
CMI: CD4's and MP's
71
airborne fungi settling on burn/wound
aspergillus
72
soil introduced via trauma
Sporothrix schenkii
73
on own skin
Candida albicans
74
woman receives antibacterial treatment --> what fungal infection to worry about?
vaginal candidiasis
75
defects in humoral immunity (complement, antibody) associated with susceptibility?
generally not
76
defect in the oxidative killing capacity of phagocytes
CGD
77
lack of mature T and B lymphocytes; results in death <1 year
SCID
78
inherited grab bag
C-type lectin (receptor pathway components)
Signaling components
Cytokines and receptors
79
Inflam/autoimmune diseases leading to fungal susceptibility
RA, IBS, SLE, psoriasis
80
Drugs that increase susceptibility
cyclophosphamide
radiation --> neutropenia
steroids --> supp antimicrobial phagocyte action
infliximab/etanercept (block TNFa)
calcineurin inhibitors (block T cell activation)
--> cyclosporin A, tacrolimus
Mycophenolate mofetil --> blocks T and B cell proliferation and fxn for transplant
81
are ma's antibodies protective against fungal infection?
negatron
82
other viruses that increase fungal susceptibility
Herpes
| CMV, EBV, HIV (CD4/MP's)
83
diabetes mellitus impact
hyperglycemia and acidosis
| diminished phagocyte fxn
84
monomorphic budding yeast w/capsule, worldwide found in soil, fruit, juice, milk, bagpipes, GUANO, pigeons, spelunking
Cryptococcus neo
| can disseminate via blood or lymph
85
disease distribution matching eucalyptus trees (reservoir) Australia, hawaii, california, BC, NW US
C. neo var. gattii (serotypes B and C)
| more virulent can infect immunosufficient
86
C. neo major form causing human disease
var. grubii (serotype A)
87
aerosolization of unencapsulated yeasts w/no capsule inhaled to small airways; also sexual spores/condida
C. neoformans
| respiratory/GI acquisition
88
pulmonary presentations of C. neoformans
DIP, pleural effusion, ARDS
89
disseminated presentations of C. neoformans
fungemia -->
meningitis (most serious; AIDS pts)
skin
prostate (reservoir)
90
potential reservoir for C. neoformans
prostate
91
leading cause of meningitis in AIDS pts? how to tx?
C. neoformans
| lifelong fluconazole, antiretroviral therapy
92
virulence determinants of C. neoformans
growth at 37C
| capsule (GXM is Cn ANTIGEN)
93
diagnostic criterion for cryptococcosis (hint: it's a virulence determinant)
capsular antigen in SERUM or CSF
94
how is C. neo capsule production regulated?
moisture, CO2, iron
small yeast --> dry soil low CO2 and iron (easily aerosolized)
moist env w/high CO2 and iron deprivation = SWELLING --> more effective inhibition of host defenses
95
phenoloxidase activity as a virulence determinant of C. neo
CNS --> catecholamine-rich (phenoloxidase substrates) --> pigmented melanins --> free radical scavengers and thus resistance to oxidative stress
Melanin coat confers extreme resistance to other host stresses (drugs, pH, temperature, UV, phagocytes)
96
diagnosis of C. neo
CSF LA test
also blood, serum, sputum, urine
DEFINITIVE: culture (slow and least-sensitive)
all tests are highly specific
97
cryptococcal antigen (latex agglutination) test for C. neo
most SENSITIVE
CSF or serum for capsule
allows quantitative assessment of fungal burden
98
India ink test for C. neo
CSF
"HALO" surrounding fungal cells
quick/easy but NOT sensitive
99
Microscopic histology of tissue for C. neo
SOCCER BALL encapsulated yeasts (lung biopsy e.g.)
100
tx of C. neoformans (severe, mild, prophylactic, subclinical)
severe: amphotericin B + 5-flucytosine
after improvement/less sever: fluconazole
prophylaxis: fluconazole (high-risk pts or persistent sub-clinical infection) low CD4 count? --> for life
101
broad, ribbon-like, septate hyphae in tissue or necrotic debris
zygomycetes
102
primary risk factors for zygomycosis
trauma, break in skin, inhalation
rapidly invasive/destructive
usually not assoc with immunocomp
103
secondary risk factors for zygomycosis
```
typically defects in innate immunity
neutropenia
immunosuppressive therapy
iron chelation
acidosis (b/c acidification causes iron to fall off transferrin)
DM, especially DKA
```
104
cryptococcal antigen measured (tells us what)?
capsular polysacc
| fungal load
105
big cryptococcal disease
meningitis
106
how to dx cryptococcal meningitis?
india ink
| culture and slide agglutination
107
tx cryptococcal meningitis in AIDS pt
acute amphotericin B
fluconazole prophylaxis
now ART to maintain CD4 levels
108
which C. neoformans variant is common in Europe?
neoformans (serotype D)
109
leading cause of meningitis in pts with AIDS
Cn
110
ABCD serotyping of Cn based on?
Capsule
111
cryptococcal capsule (or shed antigens) pathogenic mechanisms
antiphagocytic
depletion of complement
down-modulation of immune responses
112
the hyphal (mold) form invades tissue, the yeast form is commensal on the body surface
candida albicans
113
all filamentous forms: hyphae, pseudohyphae, germ tubes are considered?
invasive
114
oropharynx, GI, vagina, intertriginous, perioral, perianal colonization
not found on dry areas
albicans
115
albicans pathogenic action
skin, nail, mucosal in immunocompetent
| invasive/disseminated in immunocompromised
116
RF's for candidiasis
```
Abx/age
chemo/neutropenia
gastric acid suppression
abd surgery
CVC's, TPN, genetics
```
117
dermatitis, onychomycosis, paronycho, OE
candida
118
vulvovaginal, orophar (thrush), esoph, perianal
candida
119
extensive, chronic, tx-resistant superficial infection w/o dissemination accompanied by T-lymphocyte/MP defects but NORMAL HUMORAL responses
chronic mucocutaneous candidiasis
120
fungemia --> sepsis, endocarditis, UTI, meningitis, pneumonia, endophthalmitis
candida
121
infects virtually all individuals with AIDS
candida albicans
122
4th leading cause of nosocomial bloodstream infection
candida
123
approach to candida infection
culture --> determine spp --> susceptibility testing
124
candida virulence factors
morphogenesis
adhesins (mimic CR3/CR4 on host phagocytes)
BIOFILMS
hydrolytic enzymes
125
vulvar erythema, pruritis, thick CHEESY vaginal discharge, EXTERNAL dysuria
Vulvovaginal candidiasis (yeast infection)
126
Dx VVC
pelvic speculum exam --> WHITE plaques
vaginal fluid results: pH 4-4.5 (higher if bacterial)
calorimetric metabolic profiling
127
microscopic exam of KOH prep VVC shows?
filamentous hyphae, pseudo, germ tubes
| glabrata --> only budding yeasts (no filamentous form)
128
Culture for VVC shows?
germ-tube test: + if albicans (differentiates from other candida spp)
129
adherent white plaques on tongue, buccal mucosa, or corner of mouth (angular shelties), asymptomatic or painful, can lead to esophagitis (in severe immunocompromised)
oropharyngeal candidiasis
dx based on clinical presentation
confirm via micro exam of KOH prep via skin scraping
130
a candida syndrome occurring in pts with CMI compromise (AIDS, premies), GI leakage, foreign body
disseminated candidiasis (bloodstream infection)
131
dx disseminated (bloodstream) candidiasis
culture blood, CSF, peritoneal fluid
definitive, significant, limited sensitivity
also Beta-D-glucan in blood/fluids via LIMULUS horseshoe crab assay (cell wall component marker for invasive)
also detection of antigen/metabolites/enzymes/PCR:rDNA
132
tx candida (mild/moderate/severe)
mild: topical antifungals/oral azoles
moderate: IV azoles or echinocandins
serious: IV echinocandins or amphotericin B (bloodstream)
probiotics also an option??
mucosal/cutaneous infection in immunocompetent pt (or baby/or pt with mono) may not receive tx
133
tx AIDS pt w/oropharyngeal candidiasis
tx AIDS pt w/candida esophagitis
nosocomial candidemia?
topical antifungal
topical antifungal + oral azoles
IV antibiotics (amphoB)
134
candida spp (2) resistant to fluconazole
glabrata/krusei
| albicans susceptible
135
exists as mold only, airborne --> inhalation --> hypersensitivity w/germination to form invasive hyphae
aspergillus spp
136
Aspergillus syndromes (infection w/viable fungi not necessary)
allergy/hypersensitivity pneumonitis/ABPA
mycotoxicosis --> aflatoxins (seeds, nuts, corn; india/africa)
cavitary colonization --> aspergillomas --> hemoptysis
invasive pulmonary aspergillosis --> hemoptysis
dissemination
137
risk factors and tx of aspergillomas
```
TB, emphysema, smoking, a-1-antitrypsin def
surgical excision (cavity action)
```
138
RF's for invasive/disseminated aspergillosis
neutropenia
transplant
AID/CGD
chemo/steroids
139
colonization via aspergillus assoc w?
cavitary lesions
140
corticosteroids impair function of WAT?
macrophages --> high risk for IPA and disseminated aspergillosis
141
aspergillus virulence factors
allergens
toxins
hydrolytic enzymes
142
aspergillus dx
best: microscopic histology or beta-D-glucan marker for invasiveness; or aspergillis galactomannan assay
also culture of tissue/fluid to look for BRANCHING SEPTATE HYPHAE, but variable and low sensitivity
143
branching septate hyphae
aspergillus
144
xray or CT of IPA shows?
halo sign (early: represents HEMORRHAGE)
air-crescent sign (late: rim of cavitation as NP's recover)
highly suggestive but not diagnostic
pts with IPA aren't nec coming in coughing up a bunch of sputum, bc they don't have full innate defenses
145
tx of aspergillosis (DOC?)
DOC: voriconazole
high-dose Ampho-B
transplant: vori + echinocandin
146
drug for aspergillus prophylaxis in immunocompromised pts?
Posaconazole
147
2 morphologic forms of Pj
trophozoites --> nonrefractive, active, motile (predominant)
| cysts --> refractive, non-motile, thick-walled
148
```
no ergosterol, yes cholesterol
not susceptible to amphoB
susceptible to anti-parasitic agents (TMP-SMX)
life-cycle similar to parasites
fragile cell wall
no in vitro culturable form
```
Pj attributs atypical for a fungus
149
evidence for Pj is a fungus
chitin and B-glucans in cell wall
sensitive to echinocandins
genes/arrangements
rDNA --> gold std
150
room air, apple orchard
pneumocystis j
151
ID'd from the lungs of infected people/animals but CANNOT be cultured in vitro
Pj
152
most common disease of Pj? route of infection?
pneumonia
common env exposure (very early in life)
respiratory
153
other Pj facts
don't know a lot about this guy
host specificity suggests a non-human reservoir is unlikely
don't know infectious form
154
trophozoites damage pneumocytes and cause loss of cells lining alveoli --> FOAMY eosinophilic exudate fill alveoli --> HONEYCOMB --> gas exchange compromised --> pO2 descends
diffuse interstitial pneumonia
can also disseminate
155
70-80% of AIDS pts infected; COD in 15-20%
P. jiroveci (extreme opportunist)
156
dx P. jiroveci
gold std: histo via biopsy/BAL/sputum
Beta-D-glucan in blood/fluids (nonspecific)
NO CULTURE (can't)/SEROLOGY (everyone is seropositive)
157
tx P. jiroveci
acute: TMP-SMX
high-risk prophylaxis: TMP-SMX
also dapsone (and anti-parasite drugs)
STEROIDS to dampen host inflammatory response; along with antimicrobials, ESPECIALLY w/fluid accum in lungs!
158
candida infection typically exogenous/endogenous?
endogenous
159
germ tube induction in serum diagnostic for?
candida albicans
160
sporothrix form at 37 deg?
yeast
mold at room temp
thermoregulated morphogenesis
unlike candida, which can be present in all forms
161
if you see only yeast on histo it's probably...
candida glabrata
162
cutaneous candidiasis sx
redness, pain, pruritis
163
most common dissemination site for candida
kidney
164
PICU (neonates) candidiasis?
| elderly?
C. parapsilosis
| C. glabrata
165
fluorescence on wood's lamp via?
cell wall
166
what bacteria can cause disease similar to the subcutaneous mycoses?
mycobacteria
