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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