Intro to Mycology Flashcards
1
Q
What are the components of fungi that anti fungal medications target?
A
- ergosterol in plasma membrane
- chitin in cell wall
2
Q
general characteristics of fungi?
A
- eukaryotic
- nucleus with nuclear membrane
- subcellular organelles (mitochondria, ribosomes, ER, Golgi, microtubules
- plasmalemma (plasma membrane) composed of glycoproteins, lipids, ergosterol
- cell wall contains chitin (polymer of N-acetyl glucosamine), mannans, glucans, other complex carbs
3
Q
What is the plasma membrane of fungi composed of?
A
- glycoproteins
- lipids
- ergosterol
4
Q
What is the cell wall composed of?
A
- chitin (polymer of N-acetyl glucosamine)
- mannans
- glucans
- other complex carbs
5
Q
Comparison of fungi and bacteria? (4)
A
pic
6
Q
Types of fungi?
A
- mold
- yeast
- dimorphic fungi
- dematiaceous fungi
7
Q
Mold?
A
- filamentous form of fungi
- the mold found on foods
- reproduction: sexual and asexual spores
8
Q
Yeast?
A
- oval shaped
- single celled form of fungi
- reproduce by budding/fission
9
Q
Dimorphic fungi?
A
-fungi that grow as a mold at 25 degrees C (typically infectious form) and yeasts at 37 C
10
Q
dematiaceous fungi?
A
- not a type of fungi, just refers to pigmentation
- black or brown pigmented fungi
- often causes a type of infection called phaeohyphomycosis
11
Q
Hyphae?
A
filaments or tubular structures of molds
12
Q
Types of hyphae?
A
- septated (septa)- rigid, have cross walls (aspergillus)
- nonseptated (aseptate)- coenocytic, ribbon like (zygomycetes)
13
Q
Why is differentiating between septated and nonseptated hyphae important?
A
-it aids in differentiating between potential pathogens
14
Q
What are pseudohyphae?
A
- hyphae like structures formed by incomplete budding of yeast cells
- constricted at their point of attachment
- Candida albicans
15
Q
Mycelium?
A
mass of intertwined hyphae
16
Q
Different types of Mycelium?
A
- Vegetative mycelium
- absorbs nutrients (like roots)
- grow into growth medium - Aerial Mycelium
- contains reproductive structures
- asexual spores are called conidia
- conidiospores support chains of conidia (aspergillus)
- sporangiospores are within sac like structures (sporangium- Mucormycetes subphyla)
- spores on top of mold
17
Q
Asexual spores are called what?
A
conidia
18
Q
What is blastoconidia?
A
- conidia asexual spores
- budding yeast cell
- Cryptococcus neoforms
- tissue form of Histoplasma capsulatum (dimorphic)
- tissue form of Blastomyces dermatitidis (dimorphic)
19
Q
Microconidia and macroconidia?
A
- single or multi celled conidia
- used to spectated dermatophytes (ring worm and athletes foot cause them)
20
Q
Extracellular budding yeast?
A
- blastomyces dermatitis
- conidia
- broad based budding yeast
21
Q
intracellular yeast?
A
-histoplasma capsulatum
22
Q
Arthroconidia?
A
- conidia formed by fragmentation of hyphae
- infectious form of Coccidioides immitis
23
Q
Endospores?
A
- spores produced within a spherule
- tissue form of Coccidioides immitis
24
Q
Telemorph?
A
-fungal form producing sexual spores
25
Anamorph?
- fungal form producing asexual spores
- this state is isolated from clinical specimens
- clinical situations- asexual designations are used
26
Sexual spores are called?
- ascospores
- basidiospores
- zygospores
27
What is taxonomic classification based on?
- type of sexual spore
- classes:
- archiascomycetes
- hemiascomycetes
- euascomycetes
- basidiomycetes
- zygomycetes
- Deutoeromycete or fungi imperfecti (sexual state unknown), they are renamed if sexual state is determined (some fungi have two names)
28
Clinical classification of fungi?
- cutaneous mycoses
- superficial mycoses
- subcutaneous mycoses
- systemic mycoses
29
cutaneous mycoses?
1. dermatophytes
- molds
- cause ringworm, aka tinea
- infect skin, nails, hair (keratinized cells)
- noninvasive
2. cutaneous/mucocutaneous candidiasis
30
superficial mycoses?
- tinea versicolor- overgrowth of normal fungi which causes changes in pigmentation
- Malassezia furfur- normal skin flora
- endogenous
31
subcutaneous mycoses?
- direct inoculation into a puncture wound
- Sporothrix schenkii:
- dimorphic fungus
- associated with rose bushes and mulch
- subcutaneous ulcers that spread along the lymphatics draining the primary lesion
32
Systemic mycoses?
- involve internal organs
- often caused by opportunistic pathogens
- endemic mycoses:
- found in specific regions worldwide
- dimorphic fungi
- not opportunistic, but more likely to disseminate if the host is immunocompromised
- can be rapidly fatal (can infect multiple organs, host is already immunocompromised)
33
Types of fungi causing systemic infections, are opportunistic? (24)
chart
34
Dimorphic characteristics of endemic mycoses?
- mold- when in environment , infectious form
- yeast- when inside host
35
What are the possible classifications of candida albicans?
- yeast- when normal flora
- dimorphic- because it can form hyphae and pseudohyphae when it causes invasive disease
36
How do you differentiate between aspergillus and mucor?
- aspergillus is separated
- mucor (zygomycetes) is aseptated
37
Fungal pathogens (endemic and opportunistic)? (25)
chart
38
Characteristics of endemic fungi (systemic infections)?
- dimorphic fungi (inhale mold form, yeast form replicate in tissues)
- many cases are mild or asymptomatic
- most people in endemic area are skin test positive
- immunocompromised patients are prone to disseminated disease
39
Summary of clinical mycoses? (28)
chart
40
Diagnosis of fungal infections?
1. clinical symptoms- need to suspect fungal pathogen
2. detection of fungus in clinical specimen- rapid and economical but may not be as sensitive as culture
3. confirm by culture
4. peptide nucleic acid fluorescence in situ hybridization (PNA-FISH)
5. PCR/amplification based tests
41
Are fungal infections fast or slow growing?
slow
42
What type of stain can help see the type of conidia and/or hyphae produced?
lactophenol cotton blue
43
PNA-FISH?
- fluroescent probes for species- species rRNA sequences added to clinical specimens and visualized by fluorescence microscopy
- identifies Candida and other yeasts
44
PCR/amplification tests in diagnosis?
- limited sequence databases
- likely to be important for diagnosing mycoses in the future- target sequences being defined
45
KOH preparation?
- chitin and complex polysaccharide are not destroyed by alkali treatment
- way to look for hyphae
- can be combined with calcofluor white to make it easier to see but need fluorescent microscope
- add ink to make visualization easier
46
Gomori's methenamine silver?
- type of stain
- allows brown/black fungi to jump out in color
47
Stains for clinical specimens?
1. KOH prep
2. calcoflor white
3. Gomoris methenamine silver
4. periodic acid schiff (PAS)
5. gram stain (fungi are usually gram +)
6. general histological stains include Giemsa and hematoxylin and eosin
48
What is serology and what is it used for in fungal infections?
- antibody detection of histoplasmosis, blastomycosis, coccidiodomycosis
- mainly used to monitor disease progression
- antibody/antigen titers in serum:
- usefulness is limited by lack of sensitivity and specificity for many fungal pathogens
- can be used to monitor progression of disease and response to therapy
49
What indicates acute infection in serology?
IgM
50
What indicates recent infection in serology?
4 fold increase in IgG titer
51
What do skin tests indicate for fungal infections?
- past or present infection
- fungal antigens may induce cross reactivity with other fungi
- not diagnostic
52
What is latex agglutination used for?
to test for cryptococcal capsule
53
ELISA and latex agglutination tests are for what fungi? what they help see?
- for aspergillus and candida mannan
- helps look for antibodies and antigens
54
D-arabinitol in serum is associated with what?
disseminated candidiasis
55
D-mannitol in bronchoalveolar lavage fluid is associated with what?
pulmonary aspergillosis
56
Limulus lysate assay for beta (1,3) glucan?
- indicates presence of fungus, but doesnt identify genera
- detected in patient with invasive candidiasis and aspergillosis
