title: [Diversity of Legionella pneumophila in cooling towers: coculture kinetics and virulence studies].
abstract: BACKGROUND
  Legionella pneumophila (L. pneumophila) was isolated from three cooling towers involved in three community outbreaks of Legionnaireś disease. Each cooling tower had two different chromosomal DNA subtypes. However, only one matched identically to the clinical strains. To try to understand why only one of the environmental strains caused clinical cases we investigated the intrinsic virulence of these strains.
  
  
  METHODS
  We selected six strains of L. pneumophila sg.1: two strains (A1 and B1) from cooling tower 1, two strains (A2 and B2) from tower 2 and two strains (A3 and B3) from tower 3. One of the two subtypes (A) exhibited the same chromosomal DNA subtype as the strains isolated from the patients in each outbreak and the other exhibited a different subtype. The replication within macrophages, the presence of lipopolysaccharide epitope recognized by MAb 3/1 and the growth kinetics in BCYE broth were investigated. Isolates were typed by pulsed field electrophoresis.
  
  
  RESULTS
  The A strains did not have a higher virulence level, but were able to grow and survive better than strains B in BCYE broth.
  
  
  CONCLUSIONS
  These results suggest that the strains better adapted to the environment will manage to displace the others and will be able to spread and infect humans. The adaptation to the environmental conditions could play an important role in the pathogenesis of the strains.
authors.affiliation: Unidad de Enfermedades Infecciosas, Fundació Institut d'Investigació Germans Trias i Pujol, Universidad Autónoma de Barcelona-Esfera UAB, Badalona, España.
authors.forename: Sonia
authors.initials: S
authors.lastname: Ragull
authors.forename: Marian
authors.initials: M
authors.lastname: García-Núñez
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Pedro-Botet
authors.forename: Celestino
authors.initials: C
authors.lastname: Rey-Joly
authors.forename: Miquel
authors.initials: M
authors.lastname: Sabria
mesh_terms: D000389:Air Conditioning; D016952:Legionella pneumophila / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification* / Q000472:pathogenicity; D014871:Water Microbiology