title: Amoebae and Legionella pneumophila in saline environments.
abstract: Amoeboid protists that harbor bacterial pathogens are of significant interest as potential reservoirs of disease-causing organisms in the environment, but little is known about them in marine and other saline environments. We enriched amoeba cultures from sediments from four sites in the New England estuarine system of Mt. Hope Bay, Massachusetts and from sediments from six sites in the Great Salt Lake, Utah. Cultures of amoebae were enriched using both minimal- and non-nutrient agar plates, made with fresh water, brackish water or saltwater. Recovered amoeba cultures were assayed for the presence of Legionella species using nested polymerase chain reactions (PCR) and primers specific for the genus. Positive samples were then screened with nested amplification using primers specific for the macrophage infectivity potentiator surface protein (mip) gene from L. pneumophila. Forty-eight percent (185 out of 388) of isolated amoeba cultures were positive for the presence of Legionella species. Legionella pneumophila was detected by PCR in 4% of the amoeba cultures (17 out of 388), and most of these amoebae were growing on marine media. Our results show that amoebae capable of growing in saline environments may harbor not only a diverse collection of Legionella species, but also species potentially pathogenic to humans.
authors.affiliation: Woods Hole Center for Ocean and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 026543, USA. rgast@whoi.edu
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Gast
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Moran
authors.forename: Mark R
authors.initials: MR
authors.lastname: Dennett
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Wurtsbaugh
authors.forename: Linda A
authors.initials: LA
authors.lastname: Amaral-Zettler
mesh_terms: D016841:Amoebida / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics; D018920:Coculture Techniques; D005784:Gene Amplification; D017125:Genes, Protozoan; D019015:Geologic Sediments / Q000382:microbiology / Q000469:parasitology*; D006790:Host-Parasite Interactions; D007875:Legionella / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D016952:Legionella pneumophila / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D008404:Massachusetts; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater / Q000382:microbiology / Q000469:parasitology*; D014589:Utah
chemical_list: D001426:Bacterial Proteins; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S; C512922:Mip protein, Legionella pneumophila; D019696:Peptidylprolyl Isomerase