Intro to Mycology Flashcards
What are the components of fungi that anti fungal medications target?
- ergosterol in plasma membrane
- chitin in cell wall
general characteristics of fungi?
- 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
What is the plasma membrane of fungi composed of?
- glycoproteins
- lipids
- ergosterol
What is the cell wall composed of?
- chitin (polymer of N-acetyl glucosamine)
- mannans
- glucans
- other complex carbs
Comparison of fungi and bacteria? (4)
pic
Types of fungi?
- mold
- yeast
- dimorphic fungi
- dematiaceous fungi
Mold?
- filamentous form of fungi
- the mold found on foods
- reproduction: sexual and asexual spores
Yeast?
- oval shaped
- single celled form of fungi
- reproduce by budding/fission
Dimorphic fungi?
-fungi that grow as a mold at 25 degrees C (typically infectious form) and yeasts at 37 C
dematiaceous fungi?
- not a type of fungi, just refers to pigmentation
- black or brown pigmented fungi
- often causes a type of infection called phaeohyphomycosis
Hyphae?
filaments or tubular structures of molds
Types of hyphae?
- septated (septa)- rigid, have cross walls (aspergillus)
- nonseptated (aseptate)- coenocytic, ribbon like (zygomycetes)
Why is differentiating between septated and nonseptated hyphae important?
-it aids in differentiating between potential pathogens
What are pseudohyphae?
- hyphae like structures formed by incomplete budding of yeast cells
- constricted at their point of attachment
- Candida albicans
Mycelium?
mass of intertwined hyphae
Different types of Mycelium?
- 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
Asexual spores are called what?
conidia
What is blastoconidia?
- conidia asexual spores
- budding yeast cell
- Cryptococcus neoforms
- tissue form of Histoplasma capsulatum (dimorphic)
- tissue form of Blastomyces dermatitidis (dimorphic)
Microconidia and macroconidia?
- single or multi celled conidia
- used to spectated dermatophytes (ring worm and athletes foot cause them)
Extracellular budding yeast?
- blastomyces dermatitis
- conidia
- broad based budding yeast
intracellular yeast?
-histoplasma capsulatum
Arthroconidia?
- conidia formed by fragmentation of hyphae
- infectious form of Coccidioides immitis
Endospores?
- spores produced within a spherule
- tissue form of Coccidioides immitis
Telemorph?
-fungal form producing sexual spores
Anamorph?
- fungal form producing asexual spores
- this state is isolated from clinical specimens
- clinical situations- asexual designations are used
Sexual spores are called?
- ascospores
- basidiospores
- zygospores
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)
Clinical classification of fungi?
- cutaneous mycoses
- superficial mycoses
- subcutaneous mycoses
- systemic mycoses
cutaneous mycoses?
- dermatophytes
- molds
- cause ringworm, aka tinea
- infect skin, nails, hair (keratinized cells)
- noninvasive - cutaneous/mucocutaneous candidiasis
superficial mycoses?
- tinea versicolor- overgrowth of normal fungi which causes changes in pigmentation
- Malassezia furfur- normal skin flora
- endogenous
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
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)
Types of fungi causing systemic infections, are opportunistic? (24)
chart
Dimorphic characteristics of endemic mycoses?
- mold- when in environment , infectious form
- yeast- when inside host
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
How do you differentiate between aspergillus and mucor?
- aspergillus is separated
- mucor (zygomycetes) is aseptated
Fungal pathogens (endemic and opportunistic)? (25)
chart
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
Summary of clinical mycoses? (28)
chart
Diagnosis of fungal infections?
- clinical symptoms- need to suspect fungal pathogen
- detection of fungus in clinical specimen- rapid and economical but may not be as sensitive as culture
- confirm by culture
- peptide nucleic acid fluorescence in situ hybridization (PNA-FISH)
- PCR/amplification based tests
Are fungal infections fast or slow growing?
slow
What type of stain can help see the type of conidia and/or hyphae produced?
lactophenol cotton blue
PNA-FISH?
- fluroescent probes for species- species rRNA sequences added to clinical specimens and visualized by fluorescence microscopy
- identifies Candida and other yeasts
PCR/amplification tests in diagnosis?
- limited sequence databases
- likely to be important for diagnosing mycoses in the future- target sequences being defined
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
Gomori’s methenamine silver?
- type of stain
- allows brown/black fungi to jump out in color
Stains for clinical specimens?
- KOH prep
- calcoflor white
- Gomoris methenamine silver
- periodic acid schiff (PAS)
- gram stain (fungi are usually gram +)
- general histological stains include Giemsa and hematoxylin and eosin
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
What indicates acute infection in serology?
IgM
What indicates recent infection in serology?
4 fold increase in IgG titer
What do skin tests indicate for fungal infections?
- past or present infection
- fungal antigens may induce cross reactivity with other fungi
- not diagnostic
What is latex agglutination used for?
to test for cryptococcal capsule
ELISA and latex agglutination tests are for what fungi? what they help see?
- for aspergillus and candida mannan
- helps look for antibodies and antigens
D-arabinitol in serum is associated with what?
disseminated candidiasis
D-mannitol in bronchoalveolar lavage fluid is associated with what?
pulmonary aspergillosis
Limulus lysate assay for beta (1,3) glucan?
- indicates presence of fungus, but doesnt identify genera
- detected in patient with invasive candidiasis and aspergillosis
