Dye-containing buffered charcoal-yeast extract medium for differentiation of members of the family Legionellaceae.

The addition of 0.001% bromocresol purple and 0.001% bromothymol blue to buffered charcoal-yeast extract agar allowed differentiation between members of the family Legionellaceae. On this medium, Legionella pneumophila grew as relatively flat, pale green colonies, whereas Tatlockia micdadei (gen. nov., comb. nov., Pittsburgh pneumonia agent) produced blue-gray colonies. Fluoribacter spp. (gen. nov., atypical Legionella-like organisms) developed glistening colonies which were brighter green than those of L. pneumophila.