**2. Conclusions**

Several chemical and physical parameters can influence the behavior of *L. pneumophila* in biofilms, including the surface, the temperature, carbon and metal concentrations, and the presence of biocides [17, 18, 34, 114, 121–128]. Biological factors such as being a member of mixed species biofilm or parasitizing free-living amoeba or nematodes influence biofilm formation by *L. pneumophila*. Biofilmassociated *L. pneumophila* is resistant to biocides and Legionellosis outbreaks have been attributed to biofilms. Therefore, it is essential to design new remedies for eradication of *L. pneumophila* biofilm in different environmental settings. Treatment studies should be performed when the bacterium is in its natural host to determine how the bacterium is protected inside the amoeba and if the passages through the natural hosts modify the resistance. Thus, preventing biofilm formation appears as one strategy to reduce water system contamination.
