Tampons shouldn't be worn overnight because... 1  Tampons need to be changed every 4-6 hours and many people sleep longer than this - changing often is important as tampons allow bacterial growth while preventing vaginal cleaning so the longer a tampon is worn the more bacteria can multiply within the vagina.
MacConkey agar is a selective medium containing bile salts and crystal violet that inhibits the growth of Gram-positive bacteria while allowing for the growth of Gram-negative bacteria.MacConkey agar is often used when investigating and culturing fecal bacteria.he MacConkey agar we talked about as an example of a selective media is also a differential media. In addition to the selective bile salts and crystal violet, MacConkey agar contains a pH indicator and the sugar lactose.
Such a medium normally consists of a mixture of protein digests (e.g., peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. Standard or general purpose media will support the growth of a wide variety of bacteria â for example: TSA. A medium may be enriched by the addition of blood or serum â we use sheepâs blood agar. Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow.