Biofilm Formation by Legionella pneumophila in Water Distribution Systems: Role of Supports and Temperatures

Legionella pneumophila, the aetiological agent of 90% of legionellosis cases, is a common inhabitant of natural and in man-made aquatic environments, where it’s able to reside in biofilms. These biofilms represent a sophisticated network of metabolic and architectural interactions, which concentrates nutrients and protects the microbial residents from physical, chemical and biological hazards. L. pneumophila can form biofilms, where they become integrated and survive for days to weeks in water distribution systems depending of the environmental conditions. The materials of water distribution systems varied in their abilities to support biofilm development and the growth of L. pneumophila. Our aims of this study are to determine the kinetic of ability two strains serogroups L. pneumophila to adhere and form biofilm on three different surfaces (stainless galvanized, Copper and polyethylene) commonly used in hot water distribution system in Morocco at three growth temperatures 20, 37 and 44℃. L. pneumophila serogroup 2-15 revealed high capability to adhere and form biofilm on the stainless steel and polyethylene than serogroup 1 in 37℃ assayed incubation temperature than at 20 and 44℃. In contrast, copper was found may be to inhibit both biofilm growth and the colonization of water systems by L. pneumophila at all temperatures tested. In conclure, the selection of the suitable pipe material capable minimize the possibility of biofilm development associated in hot water distribution systems and reduce Legionnaires’ disease.