DIFFERENTIAL BUFFERRED CHARCOAL YEAST EXTRACT AGAR BASE

Description

Legionella pneumophila is a gram-negative rod responsible for Legionnaires disease. It infects the respiratory passage when airborne droplets of water are inhaled. In nature, the bacterium lives within the cytoplasm of the waterborne protozoan Hartmanella. Common sources of Legionella include cooling towers used in industrial cooling water systems as well as in large central air conditioning systems, domestic hot water systems, fountains, and similar disseminators that draw upon a public water supply. Natural sources include freshwater ponds and creeks. F-G Agar developed by Feelay et al was used for the isolation of L. pneumophila. F-G Agar was further modified by replacing beef extract and casein hydrolysate by yeast extract. Also starch was replaced by activated charcoal. The modified F-G Agar was improved by the addition of ACES Buffer (N-2-acetamido-2-aminoethane sulfonic acid). Sensitivity of the resulting Buffered Charcoal Yeast Extract Agar was increased by the addition of alpha-ketoglutarate. Differential Buffered Charcoal Yeast Extract Agar Base used for the selective isolation and differentiation of Legionella species is based on the formulation of Vickers containing the two dyes, bromocresol purple and bromothymol blue.