Mycology Flashcards
1
Q
What is a dermatophyte?
A
Fungus with the ability to obtain nutrients from keratin and therefore infects skin, hair, or nails.
2
Q
What is hyaline vs dematiaceous?
A
Hyaline is see through, dematiaceous is pigmented.
3
Q
Is it a yeast, mold, or dimorphic: Candida
A
Yeast
4
Q
Is it a yeast, mold, or dimorphic: Cryptococcus
A
Yeast
5
Q
Is it a yeast, mold, or dimorphic: Geotrichum
A
Yeast
6
Q
Is it a yeast, mold, or dimorphic: Saccharomyces
A
Yeast
7
Q
Is it a yeast, mold, or dimorphic: Rhodotorula
A
Yeast
8
Q
Is it a yeast, mold, or dimorphic: Trichosporon
A
Yeast
9
Q
Is it a yeast, mold, or dimorphic: Malassezia
A
Yeast
10
Q
Is it a yeast, mold, or dimorphic: Histoplasma
A
Dimorphic
11
Q
Is it a yeast, mold, or dimorphic: Blastomyces
A
Dimorphic
12
Q
Is it a yeast, mold, or dimorphic: Coccidioides
A
Dimorphic
13
Q
Is it a yeast, mold, or dimorphic: Paracoccidioides
A
Dimorphic
14
Q
Is it a yeast, mold, or dimorphic: Talaromyces marneffei
A
Dimorphic
15
Q
Is it a yeast, mold, or dimorphic: Sporothrix Schenckii
A
Dimorphic
16
Q
Is it a yeast, mold, or dimorphic: Rhizopus
A
Mold
17
Q
Is it a yeast, mold, or dimorphic: Rhizomucor
A
Mold
18
Q
Is it a yeast, mold, or dimorphic: Mucor
A
Mold
19
Q
Is it a yeast, mold, or dimorphic: Alternaria
A
Mold
20
Q
Is it a yeast, mold, or dimorphic: Bipolaris
A
Mold
21
Q
Is it a yeast, mold, or dimorphic: Curvularia
A
Mold
22
Q
Is it a yeast, mold, or dimorphic: Exserohilum
A
Mold
23
Q
Is it a yeast, mold, or dimorphic: Fonsecaea
A
Mold
24
Q
Is it a yeast, mold, or dimorphic: Scedosporium
A
Mold
25
Is it a yeast, mold, or dimorphic: Microsporum
Mold
26
Is it a yeast, mold, or dimorphic: Trichophyton
Mold
27
Is it a yeast, mold, or dimorphic: Epidermophyotn
Mold
28
Is it a yeast, mold, or dimorphic: Aspergillus
Mold
29
Is it a yeast, mold, or dimorphic: Fusarium
Mold
30
Is it a yeast, mold, or dimorphic: Acremonium
Mold
31
Is it a yeast, mold, or dimorphic: Scopulariopsis
Mold
32
Is it a yeast, mold, or dimorphic: Penicillum
Mold
33
How are molds sub divided?
Zygomycetes, dematiaceous, dermatophytes, hyaline hyphomycetes
34
What are zygomycetes?
This is a phylum of fungi that have broad irregularly 90 degree/right angle branched hyphae with rare septations.
35
Name the hyaline hypomycetes [5]
Aspergillus, fusarium, acremonium, scopulariopsis, pencillium
36
Name the dermatophyes [3]
Microsporum, trichophyton, Epidermophyton
37
Name the dematiaceous molds [6]
Alternaria, Bipolaris, Curvularia, Exserohilum, Fonsecaea, Scedosporium
38
Name the Zygomyctes [3]
Rhizopus, Rhizomucor, Mucor
39
Name the thermally dimorphic molds [6]
Histoplasma, Blastomyces, Coccidioides, Paracoccidioises, Talaromyces marneffei, Sporothix
40
Name the Non-Candida yeasts [6]
Cryptococcus, geotrichum, saccharomyces, rhodotorula, trichosporon, malassezia
41
Name the 6 types of candida
Albicans, brusei, parapsilosis, glabrata, tropicalis, lusitanie
42
What is the most common and 2nd most common cause of BSI with yeast?
Candida is the most common, Cryptococcus is the second most common.
43
How is candida differentiated from Cryptococcus microscopically?
Candida forms pseudohyphae and is oval shaped. Cryptococcus is larger, round, has a visible capsule and NEVER forms pseudohyphae
44
What does malassezia require to grow?
Oil or tween
45
C. albicans resistance pattern
Susceptible to fluconazole and echinocandins.
46
C. tropicalis resistance pattern
Susceptible to fluconazole and echinocandins.
47
C. Dubliniensis resistance pattern
Susceptible to fluconazole and echinocandins.
48
C. guilliermondii resistance pattern
Susceptible to fluconazole and echinocandins.
49
C. glabrata resistance pattern
Resistant to fluconazole. Susceptible to echinocandins but resistance is rising. 2nd most common candida infection
50
C. parapsilosis resistance pattern
Susceptible to fluconazole, increased MIC to echinocandins
51
C. parapsilosis causes what sort of disease?
Central line and implantable device diseases due to biofilm formation.
52
C. krusei resistance pattern
Resistant to fluzonazole, susceptible to echinocandins. May be resistant to amphotericin B and flucytosine
53
What types of patients get C. krusei infection?
Those with hematologic malignancy 2/2 azole prophylaxsis
54
C. lusitaniae resistance pattern
Resistant to amphotericin B but susceptible to fluzonazole and echinocandins.
55
C. auris resistance pattern
Resistant to fluconazole, ampho B, echinocandins
56
What is C. auris often mislabeled as?
Saccharomyces or C. haemulonii
57
Can candida cause pneumonia?
It is very uncommon and needs a biopsy for confirmation.
58
Micro shows yeast with pseudohyphae with clusters of blastoconidia at the septa. Diagnosis?
Candida
59
What infections does cryptococcus cause?
Meningitis, pneumonia, skin infections, sepsis
60
Micro shows round budding yeast with no hyphae. Diagnosis.
Cryptococcus
61
Who is at risk for cryptococcus infections?
HIV with CD4 <100, transplant recipients, those on steroids, those with malignancy and liver disease
62
What infections doe Geotrichum cause?
BSI, pneumonia
63
Micro shows arthroconidia that are in chains. Rectangle or barrel shaped. True hyphae are seen. Diagnosis?
Geotrichum
64
Risk factors for Geotrichum?
Neutropenia, heart valve surgery in immunocompromised host.
65
What infections does rhodotorula cause?
BSI, and CLABSI.
66
Micro shows unicellular blastoconidia, globose to elongated in shape. No hypae or pseudohypae. Growth is orange, red, or coral colored. Diagnosis?
Rhodotorula
67
What is rhodotorula associated with?
Central lines in immunocompromised
68
How does saccharomyces cause infection?
Associated with probiotic use. BSI. Rare infection.
69
Micro shows unicellular globuse and ellipsoid to elongated blastoconida with multipolar budding. Diagnosis?
Saccharomyces.
70
Micro shows round to oval nonbudding with comma-shaped focal thickening on the wall. Diagnosis?
Pneumocystis jirovecii
71
Micro shows small oval budding yeast at 37 degrees celsius and septate hyphae with round/pear shaped microconidia and large tuberculate macroconidia at 25-30 degrees celsius. Diagnosis?
Histoplasmosis.
72
Micro shows broad-based budding yeast at 37 degrees celsius and septate branched hyphae with intercalary or terminal chlamydospores at 25-30 degrees celsius. Diagnosis?
Blastomycosis
73
Micro shows round thic-walled spherules containing endospores at 37 degrees celsius and septate branched hyphae with thick-walled arthroconidia at 25-30 degrees celsius. Diagnosis?
Coccidioides
74
Micro shows large round thick-walled yeast with ship's-wheel appearance budding at 37 degrees celsius and septate branched hyphae with intercalary or terminal chlamydospores at 25-30 degrees celsius. Diagnosis?
Paracoccidioides
75
Where is paracoccidioides endemic?
South America
76
What type of infection does talaromyces marneffei cause?
Skin, CNS, bone infections
77
Micro shows small oval non-budding yeast at 37 degrees celsius with smooth conidiophores with 4-5 terminal metulae. each metulae bearing 4-6 phialides at 25-30 degrees celsius.
talaromyces marneffei
78
Where is talaromyces marneffei endemic?
Southwest and Southern China and Southeast Asia
79
What fungus has a biopsy that resembles squamous cell cancer?
Blastomyces
80
What causes rose handler's disease?
Sporothrix
81
Micro shows small fusiform budding yeast at 37 degrees celsius and narrow septate hyphae with tapering conidiophores at right angles at 25-30 degrees. Diagnosis?
Sporothrix
82
Micro shows thick-walled budding yeast at 37 degrees ant septate hyphae with round conidiophores at right angle at 25-30 degrees. Diagnosis?
Emonsia
83
What disease does emmonsia cause?
Pneumonia and skin infection
84
Who gets emmonsia?
Those with CD4 <100, this with malignancy, transplant patients. Those in South Africa
85
Micro shows branched sporangiophores with no rhizoid structure. Diagnosis?
Mucor
86
Micro shows nonbranching sporeangiophore originatinf from hyphae with rhizoid structure directly below the sporangiophore. Diagnosis?
Rhizopus
87
Micro shows brnaching sporangiophore with rhizoid structure away from the origin of sporangiophore. Diagnosis?
Rhizomucor
88
Who are at high risk for mucor? [5]
Uncontrolled DM, hematoligic malignancy, transplant, iron over-loard, or those on iron chelation.
89
What is the treatment for mucor?
Ampho B for severe infections. Psoaconazole or isavuconazole for step-down after induction or for mild/moderate infection.
90
Do dimorphic fungi ever represent contaminates?
No.
91
Do hyaline hyphomycetes ever represent contaminants?
Yes! Get lab confirmation.
92
Micro shows septate hyphae with conidiophore ending in phialides radiating around vesicle. Diagnosis?
Aspergillus
93
Micro shows septate hyphae with canoe-shaped macroconidia. Diagnosis?
Fusarium
94
Which fungus is able to sporulate inside the body and disseminate through the blood and yield positive blood cultures?
Fusarium
95
How does fusarium present?
Seen during engraftment phase post stem cell transplant with skin lesions and fevers. Often starts with cellulitis surrounding toenails.
96
Fusarium treatment?
Ampho B and vorizonazole prior to species level identification.
97
Aspergillus treatment?
Voriconazole.
98
General treatment methods for hyphomycete infections?
Ampho B for severe, voriconazole/isavuconazole for mild/moderate.
99
In general what is treatment for dematiaceous molds
Surgical debridement, ampho B or voriconazole
100
How are dematiaceous molds differentiared in tissue from hyaline hyphomyctes?
Fontana-Mason stain [stains the melanin in dematiaceous molds]
101
What fungi might grow in a patient on amphotericin? [8]
C. lusitaniae, C. auris, fusarium, aspergillus terreus, Scedosporium apiospermum, Lomentospora prolificans, Sporothrix schenckii, Pseudallesdheria boydii
102
Utility of blood culture with yeasts?
Most yeast grow well in blood cultures.
103
Utility of blood culture with dimorphic fungi?
Can be positive in severe disseminated disease but this is a slow and insensitive method.
104
Micro shows dark septate hyphae with alternating septated conidia. Diagnosis?
Alternaria
105
Who gets alternaria?
Those with hematologic malignancy HSCT, and neutropenia.
106
Micro shows dark septate hyphae with elongated septate conidia that taper at both poles. Diagnosis?
Bipolaris [tapers at both poles...bipolar]
107
Who gets bipolaris infection
Those with hematologic malignancy, HSCT, neutropenia.
108
Micro shows dark sepatate hyphae, septate curved conidia. Diagnosis?
Curvularia
109
Who gets culvularia?
Those with hematologic malignancy, HSCT, neutropenia.
110
Micro shows septate hyphae with swollen elongated conidia. Diagnosis?
Scedosporium/Lomentospora
111
Who gets Scedosporium/Lomentospora?
Immunocompromised patients.
112
Micro shows dark budding yeast like cells that eventually produce spetate hyphae and flask-shaped conidiogenous cells. Diagnosis?
Exserohilum
113
What fungus is associated with outbreaks during natural disasters?
Exserohilum
114
What fungus was associated with contaminated steroid injections?
Exserohilum
115
What type of agar do most fungi grow on?
Emmons modification of sabourauds dextrose agar or potato dextrose agar
116
What temp should fungi be incubated at?
25 degrees celsius to assist in identification of dimorphic molds
117
How long will it take for fungal cultures to become positive?
4 weeks for many, 3 days for candida.
118
What is a lactophenol cotton blue stain?
Identifies fungal structures from colonies on cultures [NOT tissue stains]. Lactic acid is a clearing agent and preserves fungal structures. Cotton blue stains.
119
What is a calcofluor white stain?
Binds to cellulose and chitin and fluoresces when exposed to long wave UV light.
120
How is pneumocystis usually idenitifed?
Direct fluorescent antibody stain.
121
What is a giemsa stain used for?
Typically to detect intracellular organisms such as malaria, chlamydia. Also detects yersinia. In mycology it detects intracellular histoplasma in bone marrow or blood smears
122
How does a gomori methamine silver stain work?
Mucopolysaccharide components of the fungal cell wall react with silver nitrate reducing it to metalic silver rendering a brown-black compound. Fungi look black on a green back round.
123
How does a periodic acid-schiff stain work in fungi?
Periodic acid attacks carbohydrates containing 1,2-glycol or OH group with conversion to 1,2-aldehydes which then react with the fuchsin-sulfurous acid to form a magenta color.
124
Utility of PAS stain?
Pan stain similar to GMS
125
What is a mucicarmine stain used for?
Histologic visualization of mucopolysaccharides in the capsule of cryptococcus neoformans/gattii. Differentiates cryptococcus from other yeasts in tissues. Can also stain Rhinosporidium and Blastomyces dermatitiddis
126
How does a fontana-masson silver stain work?
Oxidizes melanin and melanin-like pigments as it reduces silver giving a visible black color.
127
What is a fontana-masson stain used for?
Differentiates fungi that produce melanin and dematiaceous molds from those who do not. It will also be positive with capsule-deficient [and therefore mucicarmine negative] cryptococci.
128
What is T2Candida assay?
Uses Magnetic resonance to detect candida. It is 91% sensitive and 99% specific.
129
What candida can T2 detect? [5]
Albicans, tropicalis, parapsilosis, krusei, glabrata.
130
What is 1,3 beta-D-Glucan?
Cell wall component of many fungi. Typically used as a candida marker.
131
What will make beta-d-glucan positive?
IVIG, IV penicillin, pneumocysitis, histoplasma
132
What fungi is beta-d-glucan NEGATIVE?
cryptococcosis, zygomycetes
133
What is galactomannan?
It is a polysaccharide constituent of Apergillus cell walls?
134
What can make galactomannan false positive?
Fusarium, penicillium, histoplasma, zosyn, augmentin used to be positive if made before 2010. [May be positive up to 5 days after stoping abx.]
135
What can make galactomannan false negative?
Antifungal use.
136
What can make cryptococcal antigen false positive?
Rarely Trichosporon asahii, Rothia, Capnocytophaga.
137
What is the utility of the quantitative histoplasmosis assay?
Helps ascertain severity of the infection and monitors for antigen clearance.
138
On what is histoplasmosis antigen performed?
Blood, urine [most common], CSF
139
What are the sensitivities of histoplasmosis antigen?
90% positive in BAL, 75% in CSF
140
What can lead to a false positive histoplasmosis antigen?
Blastomycosis [so high that often the histoplasmosis urine antigen is used to diagnosis blastomycosis], talaromycosis, paracoccidioidomycosis, coccidioidomycosis
141
What can cause false negative histoplasmosis antigen?
Localized disease [only pulm], immunosuppression
142
What can cause false negative histoplasmosis antigen?
Localized disease [only pulm], immunosuppression
143
How do histoplasma antibodies work?
Uses immunodiffusion to report M or H precipitin bands. M band becomes positive soon after exposure and is positive in most patients. H band is seen in <20% of cases but is specific for disseminated infection, chronic cavitary pulmonary histo, or severe acute pulmonary histo.
144
Does H band clear? M band?
Yes, 6 months after infection. M band persists for years.
145
What does the presence of M band alone indicate?
Early or chronic disease.
146
What titer is sensitive for acute infection with M and H bands?
1:32 or higher.
147
What can cause a false positive histoplasmosis antibody?
Coccidioidomycosis, blastomycosis, some granulomatous disease such as sarcoid and TB.
148
What can cause false negative histoplasmosis antibody?
Immunosuppression.
149
What can cause cross reactivity with blastomyces antibodies?
Histoplasma capsulatum exposure. NOT A GOOD TEST AND IS RARELY USED.
150
How long does it take for coccidoides IgM and IgG to show up in the serum? How long does it take for it to go back down?
IgM: 1 week; persists 2-3 months
IgG: 3-6 weeks; persists 2 years
151
What coccidio complement fixation antibody titer is suggestive of dissemination?
>1:16
152
What is the utility of CF antibody titer for coccidio?
It has prognostic, diagnostic, and response to therapy.
153
What is the utility of CSF coccidio antibodies?
It is highly specific for meningitis
154
What is the utility of a coccidio antigen?
Useful in immunocompromised moreso in the setting of negative serologies and can serve as a surogate marker of fungal burden in severe disease and be used to monitor response to therapy.
