title: Replication of Legionella pneumophila in biofilms of water distribution pipes.
abstract: Biofilms similar to those present in water distribution pipes of anthropogenic aquatic systems were simulated in a rotating annular reactor using a non-Legionella community consisting of Aeromonas hydrophila, Escherichia coli, Flavobacterium breve and Pseudomonas aeruginosa. The impact of this community and Acanthamoeba castellanii on the replication of Legionella pneumophila was investigated. Despite the presence of 10(7) non-Legionella bacteria, culture and real-time polymerase chain reaction (PCR) results clearly showed that biofilm-associated Legionella bacteria only increased after intracellular replication in A. castellanii. Fluorescent in situ hybridization (FISH) staining of biofilm samples revealed that 48 h after addition of amoebae to the reactor, the amoeba population was lysing and replicated Legionella bacteria were released into the bulk water. This study demonstrated that amoebae like A. castellanii can play a crucial role in the increase and spread of L. pneumophila in anthropogenic aquatic systems and thus in the occurrence of Legionnaires' disease.
authors.affiliation: Laboratory of Aquatic Ecology, Zoological Institute, Katholieke Universiteit Leuven, Charles Deberiotstraat 32, 3000 Leuven, Belgium. Priscilla.declerck@bio.kuleuven.be
authors.forename: Priscilla
authors.initials: P
authors.lastname: Declerck
authors.forename: Jonas
authors.initials: J
authors.lastname: Behets
authors.forename: Anca
authors.initials: A
authors.lastname: Margineanu
authors.forename: Vincent
authors.initials: V
authors.lastname: van Hoef
authors.forename: Brenda
authors.initials: B
authors.lastname: De Keersmaecker
authors.forename: Frans
authors.initials: F
authors.lastname: Ollevier
mesh_terms: D048248:Acanthamoeba castellanii / Q000382:microbiology; D018441:Biofilms; D004261:DNA Replication; D005618:Fresh Water / Q000382:microbiology* / Q000469:parasitology; D016952:Legionella pneumophila / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D014881:Water Supply / Q000032:analysis*