EXAM 1 Mycology Flashcards
describe the kingdom fungi
- myceteae
- mycology - yeasts and molds
- eukaryotes
- ubiquitous in nature
- decomposers/saprophytes
- part of our normal flora (candida spp.)
- >200,000 species, <200 human pathogens
describe the fungal cell wall structure
describe the phenotypic morphology of yeasts
- single cells
- colonies in culture
- single
- creamy, mucoid
- facultative anaerobes
describe the phenotypic morphology of molds
- multicellular, filamentous
- thread-like filaments = hyphae
- hyphae interweave = mycelium
- colonies in culture
- fuzzy, velvety
- obligate aerobes
are true hyphae usually mold or yeast? what about pseudohyphae?
true hyphae = mold
pseudohyphae = yeast
what is sporulation?
- reproduction; can be either sexual or asexual
- asexual state = anamorph
- sexual state = teleomorph
describe the anamorph state
- asexual state
- mitotic division of haploid nucleus most common
- yeast reproduce by budding
- molds reproduce by producing conidia or by separation of hyphal elements
describe the teleomorph state
- sexual state
- diploid nucleus divides by meiosis
- haploid nuclei of donor and recipient fertile cells fuse
- mold can also reproduce by producing sexual spores
what are dimorphic fungi?
important group of geographically restricted (regionally endemic) pathogens that exist as a mold when cultured at 25-30*C and yeast at 35-37*C
what are opportunistic fungi?
only cause disease in compromised host
what are the 5 main risk factors for disease in humans?
- immunocompromised
- premature infants
- critically ill and hospitalized patients
- travelers and residents of endemic areas
- direct contact with animals or infected materials
name 6 examples of immunocompromised risk factors
- solid organ and stem cell transplant recipients
- advanced HIV/AIDS
- malignancy
- other immunodeficiency
- autoimmune disease
- metabolic disease
name 3 natural protection against disease
- natural barriers
- innate immunity
- cell mediated immunity
what are the advantages and disadvantages of direct microscopy?
- advantages
- fast and cheap
- disadvantage
- insensitive
what are the advantages and disadvantages of culture?
- advantages
- gold standard from sterile body site
- allows genus/species level ID and susceptibility testing
- disadvantages
- delayed results
- difficult to obtain from certain sites
- lack of sensitivity
- lack of specificity from non-sterile sites
what are the advantages and disadvantages of histopathology?
- advantages
- gold standard for invasive disease
- disadvantages
- difficult to obtain
- not species specific
what are the 3 classic diagnostic approaches?
- direct microscopy
- 10% KOH + calciflour white
- culture
- histopathology
name the 2 novel diagnostic approaches
- serum biomarkers
- cell wall components
- galactomannan
- 1,3-beta-D-glucan
- cell wall components
- direct detection
- nucleic acid amplification tests
- PCR/sequencing
- in situ hybridization
- nucleic acid amplification tests
describe the 2 current methods for identification
starting with a pure culture…
- proteomic identification
- matrix assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS)
- targeted gene sequencing
- conserved regions and variable regions in all fungi
will yeast stain gram positive or negative?
yeast stains gram positive (purple stain)
what are the 5 main candida species?
- c. albicans
- c. glabrata
- c. krusei
- c. parapsilosis
- c. tropicalis
candida spp. are part of our normal flora. where are they found?
skins, mouth, upper respiratory tract, bowel, vagina
what are common infections caused by candida spp.?
thrush, vaginitis, balanitis, diaper rash, esophagitis, intra-abdominal abscesses, blood stream infection
describe rhinocerebral zygomycosis
- aka mucormycosis (diseases caused by fungi of the order mucroales)
- rare infection. most common species
- mucor, rhizopus, rhyzomucor
- thrive in high glucose, acidic environment (ketone reductase)
- airborne spores inhaled
- anagioinvasive
- medical and surgical emergency
name the risk factors for rhinocerebral zygomycosis
- hematologic malignancy/HSCT (esp. voriconazole)
- steroids
- iron overload
- diabetes with ketoacidosis
- AIDS
- IV drug use
- trauma/burns
name the drug classes to treat candidiasis
- azoles (fluconazole)
- echinocandins (caspodungin)
- polyenes (amphotericin)
what are the two most common species of candida?
- c. albicans and c. glabrata
- c. glabrata often resistant to fluconazole
name the 6 dimorphic/endemic pathogenic fungi
- blastomyces dermatidis
- coccidiodes immitis/posadasii
- histoplasma capsulatum/duboisii
- paracoccidioides brasiliensis
- penicillium marneffei
- sporothrix schenckii
name the 6 opportunistic pathogenic fungi
- aspergillus spp.
- candida spp. (yeast)
- cryptococcus neoformans/gattii (yeast)
- mucor spp. (zygomycete)
- rhizopus spp. (zygomycete)
- pneumocystis jirovecii
name the 4 cutaneous pathogenic fungi
- malassezia furfur (yeast)
- epidermophyton spp.
- microsporum spp.
- trichophyton spp.
