What would be the color of gram positive and negative bacteria if: crystal violet was replaced with methylene blue? Gram positive – Gram negative – mordant was skipped? Gram positive – Gram negative – decolorizing step was omitted? Gram positive – Gram negative – counterstain was not used? Gram positive – Gram negative –

What would be the color of gram positive and negative bacteria if: crystal violet was replaced with methylene blue? Gram positive – Gram negative – mordant was skipped? Gram positive – Gram negative – decolorizing step was omitted? Gram positive – Gram negative – counterstain was not used? Gram positive – Gram negative –

Basic Clinical Laboratory Techniques 6E

6th Edition

ISBN:9781133893943

Author:ESTRIDGE

Publisher:ESTRIDGE

Chapter7: Basic Clinical Microbiology

Section7.7: Bacterial Identification And Antibiotic Susceptibility Testing

Problem 2CS

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Imagine you accidentally applied water during the decolorization step instead of ethyl alcohol. Which of the following outcomes would you expect? Both Gram-positive and Gram-negative bacteria would appear reddish-pink Both Gram-positive and Gram-negative bacteria would appear purple Gram-positive bacteria would appear purple and Gram-negative bacteria reddish-pink Gram-positive bacteria would appear reddish-pink and Gram-negative bacteria purple Gram-positive bacteria would appear colorless and Gram-negative bacteria reddish-pink
In the Gram stain, gram-positive bacteria are dark purple for all the following reasons EXCEPT: The primary stain, crystal violet, is dark purple The counterstain (safranin) causes the purple color to develop Thick peptidoglycan in the gram-positive cell wall prevents decolorization by alcohol Crystal violet is fixed inside the cell as a CV-Iodine complex once iodine is added None of the other four answers (All are reasons that gram-positive bacteria are purple
You accidentally switch the Crystal violet and Safranin steps during your Gram stain. When you look under the microscope, what color will a Gram positive bacteria, like Staphylococcus aureus, be? Red/Pink Purple colorless
What is the purpose of each reagent in gram-staining? Primary stain Mordant Decolorizing agent Counterstain
Are there any chemical differences between the cell walls of gram-positive and negative bacteria that might explain differences in the rate of decolorization ? Does the age of a culture affect the gram stain reaction ? Why or why not?
The bacterium Bacillus anthracis was stained with gram staining, endospore staining, acid-stain staining and capsule staining. What result would you expect to see? a. none of these answers b. gram positive, endospore negative, acid-fast negative, capsule positive c. gram negative, endospore positive, acid-fast positive, capsule negative d. gram positive, endospore positive, acid-fast negative, capsule positive e. gram negative, endospore positive, acid-fast negative, capsule negative thank you!!
what color would you expect for a gram positive microorganism for each incorrect mistakes while preforming a gram stain. For got to use iodine what would be the outcome color?
You are performing a Gram stain on Gram-negative bacteria, and you stop after the addition of the alcohol. What is the appearance of the bacteria at this point? ○ pink ○ colorless ○ blue ○ purple
Janet is doing a Gram stain on a mixed culture that is known to contain both Gram positive and Gram negative bacteria. After finishing, she realizes she mixed up the safranin and alcohol steps. What is likely to be observed when she views the slide under the microscope? All cells will appear purple, regardless of whether they are actually Gram negative or Gram positive. All cells will appear pink, regardless of whether they are actually Gram negative or Gram positive. Gram negative cells will be clear, Gram positive cells will be purple. Gram positive cells will be clear, Gram negative cells will be pink. Cells will appear clear, regardless of whether they are actually Gram negative or Gram positive.
For each of the following stains, list each of the chemicals used (in order), briefly describe what you would observe under the microscope, and list examples for each. - Gram stain (list color and example for Gram + and Gram -) - Acid Fast (list color and example for Acid Fast + and -) - Negative Stain (list color of organism stained with negative stain) - Capsule Stain (list color and example of organism with capsule) - Spore stain (list color and example of spore and cell)
After performing a Gram stain on a Gram negative bacteria, the specimen does not show pink or purple bacteria. Which of the following could notexplain why this occurred? Decolorizer was used after safranin Safranin was not used Crystal violet was not used The specimen was not heat-fixed
Which of the following acts as the decolorizer in the gram staining? A. Safranine B. Iodine C. Ethanol D. Crystal Violet