MIDTERM LEC 1: AGENTS OF YEAST Flashcards
(147 cards)
1
Q
2 classifications of yeast fungi
A
Yeast
Yeast like fungi
2
Q
Isolates that reproduce sexually,
A
Yeast
3
Q
Not capable of sexual reproduction or whose sexual state has not been discovered
A
Yeast like fungi
4
Q
How do yeast reproduce sexually
A
By forming ascospores or basidiospores
5
Q
Most common recognized yeast pathogens
A
Candida spp.
6
Q
Species most commonly isolated from clinical material
A
Candida albicans
7
Q
Where are Candida spp. naturally found as normal flora
A
GI tract
Mucous membranes
Skin
8
Q
Common risk factors of developing Candidiasis
A
1) Diabetes
2) Immunosuppressive disease or therapy
3) Neutropenia
4) AIDS
5) High dose chemotherapy
9
Q
Blood stream infections such as fungal endocarditis can be fostered by
A
Use of indwelling vascular lines
10
Q
All Candida spp. exist as what kind of form
A
Oval yeastlike forms
11
Q
All Candida spp exist as oval yeastlike forms that produce:
A
Buds or blastoconidia
12
Q
Candida spp produce hyphae and pseudohyphae except what species
A
Candida glabrata
13
Q
C. galbrata consume what sugar
A
Trehalose
14
Q
Second most common species of Candida
A
C. glabrata
15
Q
Describe the colony of C. galbrata
A
Smooth, white, creamy, domed colonies
16
Q
C. albicans and other spp may undergo what process wherein a single strain may change reversibly among several different morphotypes
A
Phenotypic switching
17
Q
most frequent infection of candida albicans causes _______ of the skin
A
erythematous lesion
18
Q
erythematous lesion is sometimes accompanied by
A
creamy, white exudate or scaling
19
Q
common sites of erythematous lesion of the skin
A
groin
between fingers and toes
under the female breast
axilla
20
Q
T or F:
workers who immerse their hands in the water for long periods of time are also at risk for infection of the hand skin
A
T
21
Q
Candida yeast infection of the nails
A
onychomycosis
22
Q
Candida yeast infection of the nail bed
A
paronychium
23
Q
clinical manifestation of oral candidiasis
A
creamy white patches (thrush/cottage-cheese like patches on the mouth) overlying erythematous buccal mucosa
24
Q
oral candidiasis is aka
A
moniliasis
25
thrush is recognized as an indicator of what
indicator of immunosuppression
26
hallmark of failed immune system
oral thrush
27
what condition can occur in heavy infection of oral thrush
dysphagia
28
oral candidiasis is a common initial infection in patients with what disease
HIV
29
T or F:
Oral candidiasis is a marker of immune failure in HIV px
T
30
inflammatory condition that affects the commissures of the mouth, causing break in the tissue with redness, crusting, and scaling
angular cheilitis
31
angular cheilitis is aka
perleche
32
angular cheilitis is often caused by:
buildup of saliva in the fissures
33
how can Candida cause angular cheilitis
due to presence of saliva, making the tissue soft allowing the Candida to infect the area (lateral fissure)
34
occurs as fungal infx on esophagus
esophagitis
35
T or F:
esophagitis cannot cause dysphagia
F
it can, due to painful lesions
36
erosive lesions of the distal esophagus and stomach resulting in substernal pain which is aggravated by swallowing
Gastrointestinal candidiasis
37
T or F:
Gastrointestinal candidiasis occurs more frequently as esophagitis and less commonly as gastritis
T
38
fungal infx in the vagina
Vulvovaginitis
39
factors of vulvovaginitis
1) Antibiotic
2) Pregnancy
3) Uncontrolled diabetes
4) Impaired immune system
40
why does pregnancy considered a risk for having vulvovaginitis
high estrogen= glycogen
41
why does diabetes put you at risk for having vulvovaginitis
increased glucose
42
vaginal discharge of vulvovaginitis
cottage cheese
43
why is Candida urinary tract infection difficult to diagnose
the yeast is frequently recovered from urine as a result of vaginal contamination or colonization of the bladder in px with indwelling catheters
44
Candida infection of the upper urinary tract
urinary tract infection
45
infection of the upper urinary tract can include necrosis of what part of the urinary tract
renal papillae
46
renal papillae necrosis occurs primarily in patients with what condition
obstructive uropathy
47
type of candidiasis that involve sources other than skin or mucous membranes
invasive candidiasis
48
isolation of Candida spp from at least one blood culture specimen with hematogenous spread of the yeast to one or more organs
Candidemia
49
onychomycosis is frequently due to
dermatophytes or non dermatophyte
50
what dermatophyte cause onychomycosis
Tinea unguium
51
what non dermatophyte cause onychomycosis
Candidal onychomycosis
52
clinical manifestation of paronychomycosis
infected area can become swollen, red, and painful, and a pus-filled blister may form
53
which parts of the body is intertriginous candidiasis commonly seen
axillae
groin
inter and submammary folds
intergluteal folds
interdigital spaces
umbilicus
54
factors of intertriginous candidiasis
1) moisture
2) heat
3) friction
4) maceration of the skin
55
diaper rash is aka
candidal diaper dermatitis
56
steps of invasion process
1) Adhesion
2) Uptake
3) Penetration
57
virulence factor of yeast that grants the ability to stick to host cells, triggering a switch to hyphal form and growth towards the host
adhesins
58
virulence factor of yeast that facilitate host cell engulfment of the fungus through stimulated endocytosis
invasins
59
how is active penetration through host cell barriers enabled
through combination of adhesion, physical force, and fungal enzymes
60
biofilm formation consists of
yeast cells (below)
hyphae (above)
61
how can Candida change its surface features and biofilm formation abilities
phenotypic switching
62
scrapings of mucosal or cutaneous lesions may be examined directly after treatment of what reagent
10-20% KOH containing calcofluor white
63
tissue specimens, scrapings and swabs from the mouth or vagina should be inoculated unto primary isolation media with or without what reagent
cycloheximide
64
what does the presence of filamentous extension from the edges of the colony indicate
microscopic indication that a pseudohyhae are being produced
65
In histological sections, Candida stains poorly with what stain
H&E
66
In histological sections, Candida stains well with what stains
Periodic Acid Schiff (PAS)
Gomori Methenamine Silver
Gridley fungus
67
definitive identification of C. albicans when germ test tube appears negative
Cornmeal Tween 80 Agar
68
what does Cornmeal Twee 80 Agar detect
chlamydoconidia produced by C. albicans
69
most generally accepted and economical method used to identify yeats
Germ tube test
70
how many percent of the yeasts recovered from clinical specimens are Candida albicans
80%
71
how many hours can germ tube test reveal the identification of organism
3 hours
72
Identify:
(+) germ tube test @ 35 C
C. dubliniensis
73
Identify:
(+) germ tube test @ 35C & 42C
C. albicans
74
Identify:
(-) germ tube test
other candida
75
define germ tube
hyphae-like extensions of young yeast cells showing parallel sides, aseptate and will not constrict at their point of origin
76
look like germ tubes but are septate constricted at their point of origin
pseudohyphae
77
what organism produce "pseudo-germ tubes"
C. tropicalis
78
describe pseudo-germ tubes
constricted at the base or point of germ tube origin
79
what does C. tropicalis form
blastoconidial germination w/ constriction
80
most commonly used conventional definitive identification of yeast
Carbohydrate assimilation test
81
T or F:
Not all Candida spp use glucose in CAT
F
all of them
82
CAT:
C. albicans
glucose
83
CAT:
C. krusei
glucose
84
CAT:
C. dubliniensis
glucose
85
CAT:
C. tropicalis
maltose, sucrose
86
CAT:
C. galbrata
trehalose
87
differential medium useful for the recovery of Candida
Chrom Agar Candida
88
different enzymes of different Candida spp. react with what substances to yield a characteristic color
chromogenic substances
89
CAC:
C. albicans
green
90
CAC:
C. dubliniensis
lighter green compared to C. albicans
91
CAC:
C. krusei
Pale pink-purplish pink
92
CAC:
C. galbrata
Creamy white
93
CAC:
C. tropicalis
Metallic blue; bluish green
94
treatment for thrush and other mucocutaneous form of candidiasis
topical nystatin or oral ketoconazole or fluconazole
95
treatment for systemic candidiasis
Amphotericin B
96
most protective measure in treatment
avoid disturbing the balance of microbiota and intact host defenses
97
T or F:
Candidiasis is not communicable
T
98
what organism causes meningitis, pulmonary disease and septicemia
Cryptococcus spp
99
CD4 count in px with AIDS infected with Cryptococcus
<200
100
in what environment is Cryptococcus abundantly found
soil, trees, pigeon droppings
101
Cryptococcus primarily affects which organs
primarily the lungs, then disseminate to the meninges and other sites
102
Serotypes of Cryptcoccus
A, B, C, D
103
A and D serotype
C. neoformans var neoformans
104
B and C serotype
C. neoformans var gattii
105
T or F:
Cryptococcus is encapsulated
T
106
how does Cryptococcus replicate
by budding from a relatively narrow base
107
how many buds are formed by Cryptococcus
usually single, but multiple buds and chains of budding cells are sometimes present
108
Cryptococcus only produces what kind of spores
blastoconidia
109
Cryptococcus does not produce true hyphae or pseudohyphae on what agar
cornmeal agar
110
Cryptococcosis is aka
torulosis/torulepsis
111
may present as a pneumonic process or more commonly, as CNS infx secondary to hematogenous and lymphatic spread from a primary pulmonary focus
Cryptococcosis
112
variable in presentation from an asymptomatic process to a more fulminant bilateral pneumonia
pulmonary cryptococcosis
113
neurotropic Cryptococcus spp
C. neoformans and C. gattii
114
most common form of dse of C. neoformans and C. gatii
cerebromeningeal
115
uncommon in C. neoformans but are the most common presentation of CNS cryptococcosis with C. gatii
Cryptococcomas (parenchymal lesions)
116
other manifestations of disseminated cryptococcosis
1) skin lesions (10-15% of px)
2) ocular infections
3) osseous lesions
4) prostatic involvement
5) asymptomatic reservoir of infection
116
Cryptococcal meningitis is also referred to as
Busse-Buschke Disease
117
when was Cryptococcus discovered
1894
118
major factors contributing to the virulence of Cryptococcus
capsule of the fungus comprises polysaccharides glucuronoxylomannan and glucuronoxylomannogalactan
119
virulence factor of Cryptococcus that functions as an antioxidant, defending against reactive oxygen species
Melanin
120
virulence factor of Cryptococcus that contribute to brain edema, advancing to cryptococcal meningitis when elevated un the CNS
Mannitol
121
what temperature does Cryptococcus grows best for survival in the mammalian host
37C
122
virulence factor of Cryptococcus that facilitates the degradation of host tissues and evasion of immune responses
secretion of proteases, phospholipases, and urease
123
adaptation strategy of Cryptococcus that involves the entry into the host via phagocytic cells and later escaping to colonize other tissues
Trojan Horse mechanism
124
adaptation strategy of Cryptococcus in which it alters capsule size and cell shape under specific conditions; aids in avoiding detection by the host immune system
Phenotypic variation
125
mode of entry of Cryptococcus
inhalation of spores or yeast cells
126
Cryptococcus in healthy individuals
mimic influenza-like symptoms (asymptomatic)
127
Cryptococcus in immunocompromised patients
hematogenous dissemination
128
specimens for culture for Cryptococcus
blood
CSF
other clinical material
129
microscopic examination of CSF with Cryptococcus
characteristic encapsulated budding yeast cells
130
colonies appearance of Cryptococcus in culture
mucoid colonies
131
stain for Cryptococcus
India ink or nigrosin
132
stained characteristics of Cryptococcus
unstained halo are seen around individual cells
133
diagnosis of cryptococcal meningitis
direct detection of capsular polysaccharide antigen in serum or CSF or urine
134
how is the capsular polysaccharide antigen of Cryptococcus detected in serum, CSF or urine
through latex agglutination or enzyme immunoassay kits
135
T or F:
all species of Cryptococcus are urease positive and the nitrate reaction rate differs
T
136
color of Cryptococcus colonies on birdseed agar
brown-black
137
brown-black color of Cryptococcus colonies is due to what substance
phenol oxidase
138
phenol oxidase assimilates what subtsance
creatinine
139
bird seed agar is aka
Niger seed/Staib's
140
gram stain appearance of Cryptococcus
classic starburst/sunburst appearance in CSF
141
Cryptococcus:
urease
positive
142
Cryptococcus:
nitrate reduction
positive
143
Cryptococcus:
inositol
positive
144
Cryptococcus:
cycloheximide
susceptible (sensitive)
145
C. neoformans is extremely difficult to distinguish from what species
C. gattii
146
key laboratory characteristic of C. gattii
usage of glycine as a sole carbon and nitrogen source in the presence of canavanine
