title: Genotypic variability and persistence of Legionella pneumophila PFGE patterns in 34 cooling towers from two different areas.
abstract: Genotypic variability and clonal persistence are important concepts in molecular epidemiology as they facilitate the search for the source of sporadic cases or outbreaks of legionellosis. We studied the genotypic variability and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns over time (period > 6 months) in 34 positive cooling towers from two different areas. In area A, radius of 70 km, 52 indistinguishable PFGE patterns were differentiated among the 27 cooling towers. In 13 cooling towers we observed >or= 2 PFGE patterns. Each cooling tower had its own indistinguishable Legionella PFGE pattern which was not shared with any other cooling tower. In area B, radius of 1 km, 10 indistinguishable PFGE patterns were obtained from the seven cooling towers. In four, we observed >or= 2 PFGE patterns. Three of these 10 indistinguishable PFGE patterns were shared by more than one cooling tower. In 27 of 34 cooling towers the same PFGE pattern was recovered after 6 months to up to 5 years of follow-up. The large genotypic diversity of Legionella observed in the cooling towers aids in the investigation of community outbreaks of Legionnaires' disease. However, shared patterns in small areas may confound the epidemiological investigation. The persistence of some PFGE patterns in cooling towers makes the recovery of the Legionella isolate causing the outbreak possible over time.
authors.affiliation: Infectious Diseases Unit, Hospital Universitari Germans Trias i Pujol, Autonomous University of Barcelona, Badalona, Spain.
authors.forename: Inma
authors.initials: I
authors.lastname: Sanchez
authors.forename: Marian
authors.initials: M
authors.lastname: Garcia-Nuñez
authors.forename: Sonia
authors.initials: S
authors.lastname: Ragull
authors.forename: Nieves
authors.initials: N
authors.lastname: Sopena
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Pedro-Botet
authors.forename: Maria
authors.initials: M
authors.lastname: Estere
authors.forename: Celestino
authors.initials: C
authors.lastname: Rey-Joly
authors.forename: Miquel
authors.initials: M
authors.lastname: Sabria
authors.forename: Maria
authors.initials: M
authors.lastname: Esteve
mesh_terms: D000389:Air Conditioning / Q000295:instrumentation*; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods*; D014644:Genetic Variation; D005838:Genotype; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D013030:Spain; D014871:Water Microbiology; D014881:Water Supply
chemical_list: D004269:DNA, Bacterial