Lab 18: MSA, MacConkey, EMB Plates Assignment

Microbiology Laboratory Manual · LibreTexts

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    Name Lab Section

    Data and Observations

    Organism Growth on EMB +/- Appearance on EMB

    Growth on MacC

    +/-

    		 Appearance on MacC Growth on MSA +/- Appearance on MSA
                 

    Post Lab Questions

    • Based on your observations in this exercise, you should be able to list several characteristics of each organism. Fill in this interpretation table. If you cannot make a determination based on these results, write in “N/A.” (Since you have already written the full scientific name of each organism, you may appropriately abbreviate them here.)
    Organism

    Gram positive/Gram

    negative

    		 ability to ferment lactose salt tolerance ability to ferment mannitol
             
    1. Compare the interpretation table above to results for a Gram Stain. Are there any discrepancies? If so list them and give a brief reasonable explanation.

    2. Is MSA selective, differential or both? What ingredient(s) make it so?

    Selective: Ingredients:

    Differential: Ingredients:

    3. Is MacConkey selective, differential, or both? What ingredient(s) make it so?

    Selective: Ingredients:

    Differential: Ingredients:

    4. Is EMB selective, differential, or both? What ingredient(s) make it so?

    Selective: Ingredients:

    Differential: Ingredients:

    5. A patient presents with an oozing, pus-filled skin lesion. You suspect a Staphylococcus aureus infection. What medium would you use to plate a sample from the lesion? What result do you expect if the Staphylococcus aureus is present?

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