MYCOVIRO - CH 59 Book Pt 2 Flashcards
Vaginal Samples
-transported to lab within ? hrs using culture transport swabs
24
Vaginal Samples
-transported to lab within 24 hrs using __
culture transport swabs
vaginal samples: both __ and __ agars be plated
selective and inhibitory
vaginal samples must be screened for __, incubated at 30C for 7 days
yeasts
vaginal samples must be incubated at (temp and how many days)
30C for 7 days
what urine sx is unacceptable for culture
24-hr urine
urine sample media must contain what ?
antibacterial agents
All tissues must be processed before culturing by: (2)
- Mincing
* Or placement in high speed lab blender
express the cytoplasmic contents of cells using pressure from the action of rapidly moving metal paddles
stomacher lab blender
what specimen may be placed directly onto the surface of appropriate culture media
BM
For optimal recovery, a battery of media should be used:
2
- Media with and without cycloheximide
* Media with and without antibacterial agent (not necessary if specimen is from a sterile site)
Agar plates – preferred because (3)
- Provide better aeration
- Larger surface area for better isolation of colonies
- Greater ease of handling
agar tends to dehydrate during extended incubation period
–minimized using: ??
culture dishes containing at least 40 mL agar and placing them in a humidified incubator
ADV OF SCREW-CAPPED CULTURE TUBES
- Easily stored
- Require less space for incubation
- Easily handled
- Lower dehydration rate
- Less hazardous
DISADV OF SCREW-CAPPED CULTURE TUBES
- Poor colony isolation
- Reduced SA
- Tendency to promote anaerobiosis
if using screwcapped culture tubes, after inoculation, must be placed in a horizontal position for at least ??? hours to allow the specimen to absorb the agar surface and avoid settling at the bottom of tube
1-2
?? tubes unsatisfactory for fungal cultures
cotton-plugged tubes
cultures should be examined at least how many times weekly during incubation
3x
– added to any media that contain or lack antibiotics
- if it is included, a medium w/o it must also be used
- partially or completely inhibits…
Cycloheximide
– recommended method for direct microscopic examination
KOH preparation
- better than KOH preparation
- slides are observed using 1) fluorescent microscopy (optimal because fungal cells fluoresce) or 2) bright field microscopy
Calcoflour white stain
Serology testing - may be useful for (4, CHAB)
- Cryptococcus
- Blastomyces
- Histoplasma
- Aspergillus
– useful but not for immunocompromised patients (incapable of producing a measurable humoral response)
Antibody testing
– sensitive method, difficult to perform and interpret
- requires a delay in testing that extends from exposure to onset of symptoms
- detection of antibody can take 2 to 3 months
- cross reactions with other fungal antibodies may be a problem
Complement fixation (CF)
– simple, cost-effective procedure
- 100% specific, relatively insensitive, not used as a screening tool
- requires 2-3 weeks to be positive
Immunodiffusion testing
– frequently negative in immunocompromised patients especially early in the infection
Enzyme immunoassays
- not accepted as a routine diagnostic tool in mycology
Molecular Detection
– biophysical method that reduces time required to specifically identify fungal organisms
MALDI-TOF
MALDI-TOF MEANING
Matrix-Assisted Laser Desorption Ionization
For Yeast ID
Many automated and semiautomated commercial systems have been designed with WHAT tests because C and N source differences are key to yeast differentiation)
assimilation and fermentation
o – differentiates yeast presumptively
Chromogenic agar
ID factor Most helpful when a mold culture is examined
Growth rate
– form mature colonies in 11 to 21 days
slow growers
– 6 to 10 days
Intermediate-growers
– 5 days or less
Rapid-growers
– various elevations on agar plate
• Colony topography
Colony topography
furrowed or convoluted
verrucose
Colony topography
slightly raised in the center
umbonate
Colony topography
– furrows radiate out from the center
rugose
colony texture
loose, high aerial mycelium
cottony
colony texture
low aerial mycelium resembling a velvet cloth
velvety
colony texture
smooth surface with no aerial mycelium
glabrous
colony texture
– dense, powdery, like sugar granules
granular
colony texture
high aerial mycelium like slightly matted down
wooly
o Fungi Preparation for Microscopic Examination (4)
- Cellophane (Scotch) tape preparation – traditional; easy and quick
- Wet mount
- Tease mount
- Microslide culture method
Fungi Preparation for Microscopic Examination – traditional; easy and quick
Cellophane (Scotch) tape preparation
Fungi Preparation for Microscopic Examination
used when greater detail of morphology is required
• Microslide culture method
hyphae type
curved freely branching, antler-like
antler hyphae
hyphae type
– enlarged, club-shaped
Racquet hyphae
hyphae type
produced by some dermatophytes; coiled corkscrewlike
spiral hyphae
type of hyphae common in dermatophytes
spiral
asci contains how many ascospores
4-8
Types of Conidia (both types not specific)– small, unicellular, round, elliptical or pyriform
-may be born directly on the side of a hyphal strand or at the end of a conidiophore
Microconidia
Types of Conidia (both types not specific)
large, multiseptate, club or spindle shaped
-borne on a short to long conidiophore
-may be smooth or rough walled
Macroconidia
– pinching off
-manner by which conidia are freed from their point of attachment
Abstriction
– formed directly from the hyphae by fragmentation through the points of septation
-mature: square, rectangular, barrel-shaped, thick-walled cells
Arthroconidia
– round, thick-walled spores formed directly from differentiation of hyphae in which there is a concentration of protoplasm and nutrient material
-resistant resting spores
Chlamydoconidia (chlamydospores)
-may be intercalary (w/in hyphae) or terminal (end of hyphae)
Chlamydoconidia (chlamydospores)
Chlamydoconidia (chlamydospores) within hyphae
intercalary
Chlamydoconidia (chlamydospores) at end of hyphae
terminal
o If a laminar flow BSC is used, a BSC with??? not necessary.
gloves
• Yeast cultures may be handled on a __
bench top
??? is suitable for decontaminating a loop used to transfer yeast cultures
Eletric incinerator or gas flame
• Cultures of organisms suspected of being pathogens should be??? to prevent laboratory contamination and should be autoclaved as soon as definitive ID is made.
sealed with tape
