Procedures for the recovery of legionella from the environment

"Illness caused by the gram-negative bacteria in the genus Legionella is referred to as legionellosis. Legionellosis consists of two distinct clinical syndromes, Legionnaires' disease and Pontiac fever. Legionnaires' disease is characterized by pneumonia wherase Pontiac fever is a self-limiting, nonpneumonic, influenza-like illness. Inhalation of aerosols containing the bacterium is presumed to be the primary means of acquiring legionellosis. Aerosolized waters from cooling towers, evaporative condensers, showers, and humidifiers have been identified as sources of infection. Legionella species have been recovered from a wide variety of domestic water systems and are ubiquitous in freshwater environments. Although once considered transient contaminants of natural and domestic waters, legionellae are now known to be free-living organisms surviving as natural components of freshwater ecosystems. Domestic systems are complex environments in which concentrations of legionellae can fluctuate considerably depending upon water temperature, biocide levels, and presence of natural hosts (i.e. protozoa) for legionellae to parasitize. The choice of procedure used to recover legionellae from water samples is dependant upon the expected degree of bacterial contamination in a particular water source. Potable waters generally have low bacterial densities and are either cultured directly or concentrated to detect legionellae. Nonpotable waters, such as those from cooling towers, generally do not require concentration because of their high bacterial concentrations. This manual describes the procedures currently employed by the Centers for Disease Control to process environmental samples obtained during investigations of legionellosis outbreaks. It includes information of the collection and concentration of water samples, preparation of samples for bacteriologic examination, formulas for media, sources of reagents, and air sampling techniques." - p. 1Collection of specimens -- Preparation of specimens for bacteriologic examination -- Plating of specimens -- Examination of cultures for legionellae -- Heat enrichment -- Air sampling -- Appendix 1. Preparation of media -- Appendix 2. Reagents for acid treatment procedureNational Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases, Respiratory Diseases Laboratory Section."January 2005."Available via the World Wide Web as an Acrobat .pdf file (3.61 MB, 15 p.).Includes bibliographical references (p. 13)