20 MSA, MacConkey, EMB Plates Assignment
Emilie Miller, Ph.D
Name Lab Section
Data and Observations
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Organism |
Growth on EMB +/- |
Appearance on EMB |
Growth on MacC +/- |
Appearance on MacC |
Growth on MSA +/- |
Appearance on MSA |
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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.)
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Organism |
Gram positive/Gram negative |
ability to ferment lactose |
salt tolerance |
ability to ferment mannitol |
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- 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?
