Laboratory Diagnosis Flashcards
What is the wavelength used when checking for M. audouinii infections on Wood’s lamp?
365nm
What is the cleanser used on skin and nails before sampling?
70% isopropyl alcohol
What is the most sensitive method used for isolating blood and bone marrow?
Isolator tube method
What refers to the system that is used in the isolator tube method?
lysis centrifugation system
What is the method used for isolating blood and bone marrow that uses a biphasic system (broth and agar)?
Septi-check method
True or False.
Blood culture bottles are used for specimen collection.
False (blood culture bottles is NOT RECOMMENDED)
2 drops of CSF on laboratory diagnosis are used for?
- India ink preparations
- Latex agglutination
What is used to digest respiratory specimens?
N-acetyl-L-cysteine
On KOH preparations, what is added for the rapid breakdown of cellular debris and requires no heating?
Dimethyl sulfoxide
On KOH preparations, what fluorescent dye is added that makes fungal elements to be apple-green or blue-white in color?
Calcofluor white
What component of Lactophenol Cotton Blue stains the chitin found in the fungal cell walls?
Cotton Blue
What component of Lactophenol Cotton Blue preserves fungal structures?
Lactic acid
What negative stain is used to examine CSF for the presence of C. neoformans?
India ink
Identify the tissue stain.
- polysaccharides
- color of fungal element: purplish-red or magenta
Periodic Acid-Schiff
Identify the tissue stain.
- melanin
- color of fungal element: dark brown, black
Fontana-Masson
What test for molds uses hair fragments that are floated on sterile water supplemented with 10% yeast extract?
Hair perforation test
What test for molds uses Christensen agar as the culture media for differentiating T. mentagrophytes and T. rubrum?
5-day Urease Test
What is the result when a 5-day Urease Test indicates pink or fuchsia in its results?
Positive (T. mentagrophytes)
What test is used to differentiate M. canis and M. audouinii?
Growth on rice grains
What is the most important and easiest to perform for yeast identification?
Germ tube production
What test is used to identify which carbohydrates the yeast can use aerobically?
Carbohydrate assimilation
What standard media inhibit bacterial growth?
Gentamicin and chloramphenicol
What standard media inhibit bacteria and many of the environmental fungi-typically considered contaminants?
Cycloheximide
At what temperature do most laboratories routinely incubate fungal cultures?
30℃ (room temp.)
If the causative agent suspected is a dimorphic
fungus, what temperature should the culture be incubated?
35°C
What is the most common procedure for microscopic examination?
Direct mounting of fungal isolate
What should you prepare for fungal microscopic examination when you recovered a fungus that is atypical or uncommon?
slide culture
What is used to fix and stain tease or tape mounts from cultures?
Lactophenol cotton blue (LPCB)
True or False.
LPCB does not work well with the phaeoid fungi.
True
Use of the _______ is a fairly rapid, easy, and accurate method to determine the ability of yeasts to use nitrate as the sole source of nitrogen.
modified KNO3 agar (potassium nitrate)
What method determines the ability of yeasts to use nitrate as the sole source of nitrogen?
Potassium nitrate assimilation
What indicates a positive KNO3 assimilation?
medium turns blue
An important component of the cell wall of various fungi, including pathogenic yeasts and molds.
(1,3)-β-D-Glucan
A chromogenic assay test based on the activation of the horseshoe crab coagulation cascade by (1,3)-β-D-glucan and uses amebocyte enzymes from Limulus polyphemus.
Fungitell test
A component of the Aspergillus cell wall that is used in the diagnosis of probable invasive aspergillosis caused by Aspergillus spp.
Galactomannan
An enzyme-linked immunosorbent assay (ELISA)
method, which uses a rat monoclonal antibody
directed against an epitope in galactomannan
Platelia Aspergillus Assay
A combination of nuclear magnetic resonance
spectroscopy with PCR to detect Candida cells directly in blood samples.
T2 Magnetic Resonance
Has excellent analytical sensitivity, being able to
detect 1-3 colony-forming units (CFU) of Candida per milliliter (mL) of blood
T2 Candida Assay
What is the most commonly used method for immunodiagnosis of fungal disease, but has interlaboratory discrepancies?
Double immunodiffusion
- a polyene
- primary antifungal agent for many years
- lethal to fungi, but it is also toxic to patients
- remains the drug of choice for most life-threatening fungal disease
Amphotericin B
What class of drugs for treating fungal infection has the largest number of agents and exhibit reasonable activity against fungi while causing fewer side effects?
Azoles
- the leading agent for treating yeast infections but has limited to no activity against molds
- widely used by many practitioners to treat infections such as vaginitis and thrush
Fluconazole
What antifungal susceptibility testing method is used for yeast testing?
M27-A3
What antifungal susceptibility testing method is used for yeast disk diffusion?
M44-A
What antifungal susceptibility testing method is used for mold testing?
M38-A2
What antifungal susceptibility testing method is used for mold disk diffusion?
M51-P
What bacterial testing eliminates the need for multiple media to perform antimicrobial susceptibility testing?
Mueller-Hinton Agar
an endpoint that can be used to evaluate a given MIC when clinical breakpoints are not available
Epidemiologic cutoff values (ECV)
What is the first agent in the echinocandins group that is lethal for yeast, targets cell wall synthesis, but is effective against aspergilli?
Caspofungin
A rapid point-of-care dipstick test that uses a
monoclonal antibody against the cryptococcal
antigen.
Lateral flow assays
