(Part 1) 1.13 Gram stain Flashcards
Provides a rapid presumptive identification of pathogens
Gram stain
Who devised Gram stain?
Hans Christian Gram
Color of Gram neg?
Pink
Color of Gram positive
Purple/Violet
Reagents of Gram stain?
Crystal violet (10 -30 secs)
Iodine (2x as long as CV)
Acetone (10 sec)
Safranin (30 sec)
Fixes primary stain in to the cell wall
Mordant
Main target of pimary stain
Peptidoglycan
What is the color of gram neg during decolorization?
Clear
Crystal violet stains both gram pos and neg?
T or F
T
Reason for why Gram negaive washes away primary stain?
Thin peptidoglycan
Contains lipids that can wash away the primary stain when decolorizer is applied
What is the counter stain in gram stain?
Safranin
Most critical step in gram staining that allows differentiation of gram negative and gram positive?
Decolorization
All cocci are Gram positive except?
Neisseria
Veillonela
Moraxela
NVM
All bacilli are gram negative except?
Bacillus
Mycobacterium
Actinomycetes
Arcanobacterium
Corynebacterium
Clostridium
Nocardia
Erysipelothrix
Listeria
Lactobacillus
Propionibacterium
BMAACCNELLP
Common test perform in the laboratory for gram positive?
Catalase test
Oxidase test
Ommision of Crystal violet resulted to?
Pink color
Omission of Mordant resulted to?
Pink color
Omission of Decolorizer resulted to?
All Violet
Omission of Safranin resulted to?
Gram positive: Violet
Gram negative: Clear/Colorless
Applying gram stain to old cultures may result to?
Pink color
Because of deterioration of cell wall, Primary stain may not be applied
Excessive heat fixation during gram stain may result to?
Pink
Cell wall may be destroyed
Over decolorization during gram stain may result to?
Pink
Excessive decolorization may remove all violet colors even in Gram-positive bacteria
Excessive washing during gram stain may result in?
Pink/colorless
Regardless of which part of the procedure, excessive washing may remove the bacteria in the stain. or even the primary stain.
Gram iodine is acid or alkaline?
Alkaline
What to evaluate when examining gram stain in microscope?
Gram Reaction
Morphology
Arrangement
Presence of inflammatory cells
Others:
Squamous
tissue debris
Report absence of bacteria is any
How to report the relative amount of bacteria?
Rare, Few, Moderate, Many
1+, 2+, 3+, 4+
