- Mannitol Salt Agar (MSA): MSA is a selective and differential medium used for the isolation and differentiation of pathogenic staphylococci, particularly Staphylococcus aureus. It contains a high concentration of sodium chloride (7.5%), which inhibits the growth of most other bacteria. Mannitol is a fermentable sugar, and S. aureus ferments it, producing yellow colonies surrounded by a yellow zone due to the production of acid.
- MacConkey Agar (MAC): MacConkey Agar is a selective and differential medium used for the isolation and differentiation of Gram-negative bacteria, particularly those associated with urinary tract infections and enteric infections. It also contains a high concentration of sodium chloride (7.5%), which inhibits the growth of most Gram-positive bacteria. Lactose is a fermentable sugar, and some Gram-negative bacteria, such as E. coli, ferment it, producing pink colonies due to the production of acid.
