[2S] UNIT 5 Exercise 5 Flashcards
Have been regarded the foundation of a repertoire of diagnostic tests for detection of fungal infections.
Direct Microscopy
Culture
Histopathology
This does not only enhance visualization of cell components but also provides contrast and can highlight a metabolic process.
Fungal-specific stains
Provides rapid presumptive test for detection of fungal elements such as hyphae and budding yeast, in clinical specimens
Microscopy
Staining of fungal components for light microscopy plays a vital role in diagnosis of encapsulated fungi such as _______, ________ and other medically important fungi.
C. neoformans, Candida spp.
ODD ONE OUT: FACTORS THAT INFLUENCE THE SENSITIVITY OF A MICROSCOPIC EXAMINATION
Individual fungal agent
Source
Quality & Prep of the Specimen
Exp & Expertise of the Lab Scientist
wla
T/F: Factors such as the individual fungal agent, the source, quality and preparation of the specimen, and the experience and expertise of the laboratory scientist influence the sensitivity of a microscopic examination
T
These procedures may require the use of ______ of deep tissues, which may place one at risk particularly those patients who are most susceptible to invasive disease.
biopsies
Due consideration has to be made in the use of direct microscopy and histopathology in the diagnosis of ______ fungal infection
invasive
1st step in collecting skin scrapings & nail clippings
Sterilize the affected skin & nail with 70% alcohol
Skin scrapings are collected by scraping from the ______ _____ of lesion (as edge has greatest amount of viable fungus) with a blunt scalpel blade held at right angles to the skin.
outer edges
T/F: Blunt scalpel blade held at right angles to the skin should be used when collecting skin scrapings
T
Where to place the collected skin scales?
Sterile petri dish / wide-mouthed container
Clean paper w/ adhesive tape and label
Preferred area of the nail clipping collection
Damaged, discoloured, brittle or
dystrophic area
If a skin scraping does not yield sufficient material, then a ____ or ______ _____ could be pressed on the lesion
swab or adhesive tape
T/F: The entire thickness of the damaged nail should be cut as far back as possible. If crumbly material or material under the nail is present, collect also at this site and place in a sterile container.
T
T/F: If skin lesions are present near the nail, carefully scrape the affected area and the collected material should be sent separately.
T
T/F: Since fungal cells and other fungal elements are larger compared to bacteria, the use of dried stained smears prepared from clinical specimen is necessary.
F; unecessary
Very simple and easiest method of examining fungal structures
Wet mount or wet preparation
Routinely used solutions for mounting fluid for microscopic study of fungi
SaPoL
Saline
Potassium hydroxide
Lactophenol cotton blue
PREPARING A WET MOUNT
T/F: Place your specimen on the slide. Make sure the layer is as thick as possible.
F; thin
PREPARING A WET MOUNT
T/F: Overlay the coverslip by gently placing it at one edge of the KOH/Calcoflour white solution and slowly lower it over the sample.
T
PREPARING A WET MOUNT
Add one drop of ___ or _________ _____ (or stain) to the specimen
KOH or Calcoflour white
PREPARING A WET MOUNT
Remove the trapped bubbles by gently pressing the coverslip with the ________ or a blunt _______
eraser end of a pencil or a blunt forcep
Principle: Skin scrapings and nail clipping samples when mixed and suspended in 10-20% respectively will cause the keratin and other proteinaceous components of tissue to dissolve making the fungal elements more visible and prominent
KOH Preparation
SKIN SCRAPINGS - KOH PREP
Percentage of KOH added to the slide
a drop of 10% KOH
SKIN SCRAPINGS - KOH PREP
Leave the slide at room temperature for __ minutes
10
SKIN SCRAPINGS - KOH PREP
T/F: Excess fluid on the slide can be blot off using a piece of tissue paper
T
NAIL CLIPPINGS - KOH PREP
T/F: The nail should be cut into small pieces with the nail cutter
F; scalpel or sterile blade