MacConkey agar is a Selective & differential media use for the isolation and differentiation grams negative organisms .
It’s selective for gram negative bacteria & differential for lactose fermenting bacteria. So this is the common definition for Mac agar , we all are well known … According to this definition MacConkey Agar inhibit the growth of gram positive organisms.
And remember there ingredient call , crystal violet which important to inhibit gram positive organisms colonies on Mac agar. But there some MacConkey agar products which does not contain crystal violet reagent.
Correct answer >>> MacConkey agar without crystal violet , permits which mean not inhibit growth of staphylococcus & enterococcus .
Also Staphylococcus produce pale pink color to red lactose fermenting colonies and entero cocci produce compact tiny red colonies either on or beneath the surface of the medium.
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