title: Australian isolates of Legionella longbeachae are not a clonal population.
abstract: Legionella longbeachae is almost as frequent a cause of legionellosis in Australia as Legionella pneumophila, but epidemiological investigation of possible environmental sources and clinical cases has been limited by the lack of a discriminatory subtyping method. The purpose of this study was to examine the genetic variability among Australian isolates of L. longbeachae serogroup 1. Pulsed-field gel electrophoresis (PFGE) of SfiI fragments revealed three distinct pulsotypes among 57 clinical and 11 environmental isolates and the ATCC control strains of L. longbeachae serogroups 1 and 2. Each pulsotype differed by four bands, corresponding to <65% similarity. A clonal subgroup within each pulsotype was characterized by >88% similarity. The largest major cluster was pulsotype A, which included 43 clinical isolates and 9 environmental isolates and was divided into five subgroups. Pulsotypes B and C comprised smaller numbers of clinical and environmental isolates, which could each be further divided into three subgroups. The ATCC type strain of L. longbeachae serogroup 1 was classified as pulsotype B, subtype B3, while the ATCC type strain of L. longbeachae serogroup 2 was identified as a different pulsotype, LL2. SfiI macrorestriction analysis followed by PFGE showed that the Australian L. longbeachae strains are not a single clonal population as previously reported.
authors.affiliation: Department of Medicine, University of Sydney, New South Wales 2006, Australia. jacquiem@blackburn.med.usyd.edu.au
authors.forename: J C
authors.initials: JC
authors.lastname: Montanaro-Punzengruber
authors.forename: L
authors.initials: L
authors.lastname: Hicks
authors.forename: W
authors.initials: W
authors.lastname: Meyer
authors.forename: G L
authors.initials: GL
authors.lastname: Gilbert
mesh_terms: D001315:Australia; D016521:Electrophoresis, Gel, Pulsed-Field; D014644:Genetic Variation; D006801:Humans; D007875:Legionella / Q000235:genetics* / Q000302:isolation & purification