Staining technique (LAB) Flashcards
Decolorizing agent of AFB stain
Acid-Alcohol (3% hCl + 95% Ethanol)
used to intensify the color of the primary stain of Gram’s
mordant
What result will be if at least one sputum smear is positive for AFB
Positive
Fixation is done through______ or _____
Slide warmer /Heating , or
95% methanol
_______contribute to the ability of gram positive organisms to resist alcohol decolorization
teichoic acid cross-links / teichoic acid cross-links
Gram stain is considered a __________
differential stain
render the
cells resistant to
decolorization in AFB stain
Mycolic acid
Nearly all clinically important bacteria can be detected using gram staining method, the only exceptions being those organisms that exist ________, _____, and ________
Exclusively within host cell, lack cell wall , and Insufficient dimension on light microscope
Negative result for AFB requires _____ negative
both sputum smears (2 samples)
Kind of fixation that preserves the morphology
of host cells, as well as bacteria, and is especially useful for
examining bloody specimens
Methanol fixation
He first devised gram staining during the late nineteenth century
Hans Christian Gram
In order to establish a color contrast, the
third reagent used in Gram staining is the
decolorizing agent
enhance sputum quality detection by acid-fast stain and culture
Decontamination / Digestion
preparation of the primary clinical sample received in the laboratory for processing
Direct Smear
contains a highly crossed linked layer of peptidoglycan that retains the primary dye
Gram positive
Commonly, indirect smears use ___
pipette
Application of
safranin: Gram-positive cells are ____ ; gram-negative cells are _____
purple, pink
Commonly, direct smears use ____
swabs
during 95% alcohol wash: Gram-positive cells are purple; gram-negative
cells are _____
colorless
the acid-fast stain is only performed on specimens from
patients highly suspected of having a _____
mycobacterial infection
a staining step of Gram’s that distinguishes gram-positive
from gram-negative cells
decolorization
chemical differentiation of organisms
Differential Stain
AFB staining’s primary stain
Carbol Fuchsin
Bacterial group that take up the basic dye, crystal violet
gram positive bacteria
designed for a subset ofbacteria whose cell walls
contain long chain fatty
(mycolic) acids
Acid-Fast Staining
Indirect smears may include
preparation from _______
solid or semisolid media or broth
For staining microorganisms grown in culture or an indirect smear, a sterile ________ may be used to transfer a small amount of growth from a solid medium to the surface
of the slide
loop or needle
AFB interpretation: 10-99 AFB in 1 length
1+
The procedure requires heat to allow the primary stain
(carbolfuchsin) to enter the wax-containing cell wall
ZIEHL-NEELSEN
Standard measurement for AFB smearing
3cm x 2cm
Mordant for Gram stain
Gram iodine
Decolorizer for Gram stain
acetone/alcohol
Acid-fast–positive
bacilli color
Red
The Gram stain differentiates between bacteria based on the composition of their
cell walls
Gram negative color
Pink
applied after the crystal violet to chemically
bond the alkaline dye to the iodine, forming a CV-I complex and cross-linking the complex in the bacterial cell
wall
mordant (Gram’s iodine (I) )
Acid-Fast negative bacilli color
Blue
Primary stain for Gram’s
Crystal violet
counterstain for Gram’s
safranin
AFB stain counterstain
Methylene Blue
Cold method of AFB stain that does not require the use of heat or boiling water, minimizing safety concerns during the procedure
Kinyoun acid-fast
method
All smears should be ________ before staining
air dried
indicates that the primary sample has been processed in culture
and the smear contains organisms obtained after purification
or growth on artificial media
indirect smear
AFB interpretation:
1-10 AFB/OIF at least 50 fields
2+
A direct smear provides a mechanism to identify the
number and type of cells present in a specimen including ____-, _____, and ______
white blood cells
epithelial cells
predominant organism
principal stain used for microscopic examination of bacteria and is one of the most important bacteriologic techniques within the microbiology laboratory
Gram stain
The order of Dyes, Mordant & Decolorizer in Gram-staining procedure is
Crystal violet, Iodine solution, Alcohol, Safranine
