Martin Lewis Agar Base is a selective and enriched medium recommended for the isolation and cultivation of Neisseria species from clinical specimens. For the cultivation of fastidious organisms the medium should be supplemented with essential growth factors supplied predominantly by yeast extract. This can be replaced with a chemically defined supplement containing essential growth factors available from yeast extract in Vitamino Growth Supplement. X-factor needed for the growth of fastidious Haemophilus species is provided by hemoglobin. Selective supplement inhibits accompanying bacteria.