[Management of the Legionella-link risk in a multicentre area's hospital: lessons learned of a six-year experience].

To reduce the Legionella-linked risk in the several sites of Sud-Francilien Hospital, following a hospital-acquired legionellosis case, a multidisciplinary working group performed an action plan monitored through Legionella pneumophila counts in hot water supply. From 2003 to the first half year 2009, positive points for Legionella pneumophila in the main sites of the hospital decreased from 85.71 to 28.00%, representing a significant reduction of 67.33%. Similar results were observed for three of the four establishments, whereas the last did not describe a pronounced reduction of Legionella pneumophila counts and showed constantly serogroup 1 strains. During this period, investigations of additional cases of legionellosis demonstrated a nosocomial transmission in one case in this last site. Multidisciplinary mobilization in management of Legionella-linked risk contributed to these results.