Analysis of the impact of a new electro-chemical activation system for potable water disinfection on the Legionella pneumophila isolation rate in a Spanish hospital

摘要

On a field study comparing isolation rates pre- and post-installation of an electro-chemical activation system for Legionella pneumophila disinfection of potable hot water in a Spanish hospital, a total of 250 tap samples pre-installation and 113 post-installation were collected. Chlorine levels were higher (p< 0.001) post-installation (0.55+-0.41 vs. 1.19+-0.44ppm). Of 38.0% (138/363) samples positive for L pneumophila, 111 (80.4%) were serogroups 2-14. Post-installation, the isolation rate was lower (46.8% vs. 18.6%; p< 0.001, odds ratio (OR) 0.26, 95% confidence interval (Cl) 0.15-0.44) due to significant (p < 0.001; OR 0.25, 95% Cl 0.14-0.45) reduction in L. pneumophila serogroups 2-14 from 38.4% to 13.3%. Post-installation, isolation rates were lower in spring (44.4% vs. 0.0%; p< 0.001), summer (80.0% vs. 25.0%; p = 0.003) and autumn (72.0% vs. 28.9%; p = 0.018), but not in winter (18.5% vs. 11.8%; p = 0.688). The seasonal wave constructed with pre-installation data significantly decreased post-installation by decreasing isolation rates in summer and autumn to rates similar to those found in winter pre-installation.