Multiple choice

Which of the following ingredients in MSA makes it selective for the genus Staphylococcus?

  1. Mannitol

  2. Peptone

  3. Sodium chloride

  4. Phenol red

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

MSA has a high concentration of sodium chloride that selects for members of the genus Staphylococcus as they can tolerate high saline levels. Organisms from other genera may grow, but very weakly.