Legionella indoor air contamination in healthcare environments

Legionella spp. is a ubiquitous intracellular microorganism in aquatic environments both natural and artificial. Although Legionella pneumophila sg 1 and sg 6 are the main causes of disease, other species have recently been associated with cases of legionellosis. Since 2000, some international documents related to the control and prevention of Legionnaires’ disease have been issued, providing different environmental matrices’ sampling, but not for air. To date, the control on water mains is preferred; however, air sampling could be a useful tool for exposure evaluation. To sample biological particles in the air, active and passive methods can be used. Several studies have compared the values of microbial counts obtained with these sampling methods, attaining discordant results. Based on this scientific background and on the experience about Legionella spp. contamination and air microbial sampling in health care environments, GISIO-SItI, AIA, and SIMPIOS promoted two multicenter studies focused on identifying a standardized sampling protocol to detect the airborne contamination coming from water sources contaminated with Legionella spp.