Preferential colonization and release of Legionella pneumophila from mature drinking water biofilms grown on copper versus unplasticized polyvinylchloride coupons.

[legionellosis]

Legionella occurrence in premise drinking water (DW ) systems contributes to legionellosis outbreaks , especially in the presence of suitable protozoan hosts . This study examined L . pneumophila behavior within DW biofilms grown on copper (Cu ) and unplasticized polyvinylchloride (uPVC ) surfaces in the presence of Acanthamoeba polyphaga . One year -old DW biofilms were established within six CDC biofilm reactors : three each containing Cu or uPVC coupons . Biofilms were then inoculated with L . pneumophila (uPVC-Lp and Cu-Lp ), or L . pneumophila and A . polyphaga (uPVC-Lp /Ap and Cu-Lp /Ap ) and compared to sterile water inoculated controls (uPVC- and Cu-Control ) over a 4 month period . L . pneumophila appeared more persistent by qPCR within Cu biofilms in the presence of A . polyphaga compared to uPVC biofilms with or without A . polyphaga , but maintained their cultivability in uPVC biofilms compared to Cu biofilms . Also , persistent shedding of L . pneumophila cells (assayed by qPCR ) in the effluent water implied colonization of L . pneumophila within Cu-coupon reactors compared to no detection from uPVC-coupon reactor effluent 14 days after inoculation . Hence , L . pneumophila appeared to colonize Cu surfaces more effectively and may be shed from the biofilms at a greater frequency and duration compared to L . pneumophila colonized uPVC surfaces with host amoebae playing a role in L . pneumophila persistence within Cu biofilms .