II. DIAGNOSTIC MYCOLOGY Flashcards
produce moist, creamy, opaque or pasty colonies on media
Yeast
produce fluffy, cottony, woolly, or powdery colonies
Filamentous fungi or Molds
fungal pathogens that exhibit either a yeast or yeastlike phase and filamentous forms
Dimorphic
when dimorphism is temperature-dependent
Thermally dimorphic
mold form at
25°C to 30°C
yeast form t
35°C to 37°C
fungi that have more than one independent form or spore stage in their life cycle
Polymorphic fungi
Fungi have been categorized into three well-established phyla:
Zygomycota
Ascomycota
Basidiomycota
This diverse group of fungi includes organisms that produce sparsely septate hyphae and exhibit asexual reproduction by sporangiospores and sexual reproduction by the production of zygospores.
Zygomycota
fungi that reproduce asexually by the formation of conidia (asexual spores) and sexually by the production of ascospores.
Ascmycota
fungi that reproduce sexually through the formation of basidiospores on a specialized structure called the basidio
Basidiomycota
fungal infections that involve hair, skin, or nails without direct invasion of deeper tissue
Superficial (cutaneous) mycoses
infections that are confined to the subcutaneous tissue without dissemination to distant sites
Subcutaneous mycoses
Four categories of mycoses according to the type of infection:
Superficial (cutaneous) mycoses
Subcutaneous mycoses
Systemic mycoses
Opportunistic mycoses
infect immunocompromised hosts. ______________ include almost any fungus present in the environment
Opportunistic pathogens
Virulence factors
Size
Temp and ph (37°C at a neutral pH)
Conversion of the dimorphic
Toxin production
most common specimens collected for fungal culture
Respiratory tract secretions
prevents overgrowth by rapidly growing molds and should be included in at least one of the culture media
antifungal agent cycloheximide
are satisfactory for the recovery of fungi
Agar plates or screw-capped agar tubes
___________ are preferred, because they provide better aeration of cultures, a large surface area for better isolation of colonies, and greater ease of handling
Plates
Dishes should be opened and examined in a __________________
CERTIFIED BIOLOGICAL SAFETY CABINET
After inoculation, tubes should be placed in a _______________ for at ______________ to allow the specimen to absorb to the agar surface and prevent settling at the bottom of the tube.
Horizontal position
1 to 2 hours
___________ are unsatisfactory for fungal cultures.
Cotton-plugged tubes
● Cultures should be incubated at room temperature, or preferably at _______________ before they are reported as ___________
● Cultures should be examined at __________weekly during incubation.
30°C, for 21 to 30 days
Negative
Atleast three times
Addition of ___________________ and _________________ to media has been advocated to inhibit the growth of contaminating molds and bacteria, respectively. However, better results have been achieved using a combination of ________________________________ as antibacterial agents. _______________ at a concentration of 5 mg/mL may be used.
0.5 mg/mL of cycloheximide
16 mg/mL of chloramphenicol
5 mg/mL of gentamicin and 16 mg/mL of chloramphenicol
Ciprofloxacin
