Studies of environmental water samples for different parameters for isolation of Legionella spp.

Legionella pneumophila has frequently been isolated from patients with Legionnaires disease and in several instances also from epidemic-related environmental samples. A selective medium was developed and used successfully to isolate Legionella pneumophila and Legionella-like organisms from environmental specimens animal inoculation methods. Legionella pneumophila is a Gram-negative, facultative, intracellular bacterium that is the causative agent of Legionnaires' disease. This medium consists of charcoalyeast extract agar to which have been added cephalothin (4µg/mL), colistin (16µg/ mL), vancomycin (0.5µg/mL), and cycloheximide (80µg/mL). Pretreating of the environmental water samples with an acid buffer (pH 2.2), followed by plating on the selective medium, improved the rate of recovery of both Legionella and Legionella-like organisms relative to that with direct plating on selective media.