Role of Microscopy Flashcards
A fluorescent dye coupled with specific antibodies is called:
a. Immunofluorescence
b. Flourochroming
c. Acridine orange
d. Electron microscopy
a. Immunofluorescence
The stain that binds to the nucleic acid of organisms but does not discriminate between gram-positive or gram-negative organisms is called:
a. Ziehl-Neelsen stain
b. Auramine-rhodamine stain
c. Gram stain
d. Acridine orange stain
d. Acridine orange stain
The step in the Gram stain process that distinguishes between gram-positive and gram-negative organisms is:
a. Fixing of the cells to the slide using heat or methanol
b. Decolorization using alcohol or acetone
c. Counterstain of the Gram stain using safranin
d. Application of the mordant, Gram’s iodine
b. Decolorization using alcohol or acetone
Dark-field microcopy is used for the microscopic examination of these types of bacteria:
a. Gram-positive cocci such as S. aureus
b. Yeast such as Candida tropicalis
c. Gram-negative bacilli such as E. coli
d. Spirochetes such as Trepnema palllidum
d. Spirochetes such as Trepnema pallidum
The ocular lens is the lens closest to the specimen. True or false
False
T/F:
Resolution is the extent at which detail in a magnified image is defined.
True
T/F:
Fungi stain gram-negative
False
T/F:
Acid-fast bacteria are resistant to decolonization
True
T/F:
A fluorescent dye coupled with specific antibodies is called fluorochroming.
False
principle stain used for microscopic bacteria examination
Gram stain
stain used to detect fungi in clinical material
calcofluor white
Gram staining of clinical material
direct smear
primary stain in the classic acid-fast stain
carbolfuchsin
“hot” method of acid-fast stain
Ziehl-Neelsen
counterstain in the Gram stain
safranin
mordant that forms the intracellular complex
Gram’s iodine
primary stain of the Gram stain
crystal violet
focuses light path for proper resolution
Kohler illumination
How is contrast achieved in light microscopy?
as a result of the interaction between illuminating light wavefronts and the specimen, and how the light leaving the specimen is processed,
Calculate the total viewing magnification of an object when using the 40x objective lens
10 x 40 = 400x
What two methods of microscopy are most widely used in clinical laboratories?
Bright field and fluorescent microscopy
For what reason would the gram stain of a specimen stain gram-variable. and how should that gram stain be reported?
Gram-positive organisms that have lost cell wall integrity as a result of antibiotic treatment, old age, or other reasons will decolorize, report as gram-positive.
An indirect smear from a blood agar plate was gram stained and reported as “gram -positive cocci in clusters.” However, the gram stain of the thioglycollate broth demonstrated gram-positive cocci in chains. How would the microbiologist resolve this discrepancy, and what should be reported?
The smears prepared from each media are the same organism. When preparing a smear from solid media, it is important to make the smear is thin enough and to look to the outer edges to find the true morphologic characteristics and arrangement; all organisms tend to clump together when improperly emulsified. The broth culture allows the microbiologist to view organisms in their native states, including correct cellular morphologic characteristics and arrangement, they are not clumped together but are free floating in the liquid medium.
