A Multicenter Study on Legionella Air Contamination in Italian Healthcare Facilities: Comparison of Different Sampling Methods

Background: Healthcare facilities (HF) represent an at-risk environment for legionellosis transmission occuring after inhaling aerosols produced from contaminated water sources. The control of water is preferred to that of air because to date there are not standardized protocols sampling. Methods: Legionella air contamination was investigated in the bathrooms of 11 HF contaminated with Legionella by active sampling (Surface Air System and Coriolis®?) and passive sampling. During the 8-hour sampling, hot tap water was sampled three times and analyzed for Legionella. Air samples were evaluated using culture based methods, whereas liquid samples collected using the Coriolis©? were also analyzed by real-time PCR. Legionella presence in air and water was compared by sequence-based typing (SBT) methods. Results: Air contamination was found in four HF (36.4%) by at least one of the culturable methods. The culturable investigation by Coriolis did not yield Legionella. However, molecular investigation using Coriolis resulted in eight HF being positive for Legionella in air, which was greater than the number of positives obtained by culturable methods

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