Genotyping of Legionella pneumophila serogroup 1 strains isolated in Northern Sicily, Italy.

During a three-year period, from April 2002 to May 2005, one hundred-forty-seven samples, taken from technical systems of water distribution at point of use, were repeatedly collected at six different sites in Northern Sicily and assayed for the presence of Legionella pneumophila serogroup 1 and serogroups 2 to 14. At the first samplings, the water distribution systems of all the sites were heavily contaminated, and disinfection treatments by the superheat and flush method were therefore performed. Treatments were always successful against L. pneumophila sg.1, but only in a few cases against all other serogroups. Eighty-six strains of L. pneumophila sg. 1, isolated from 26 of these samples, were characterized by amplified fragment length polymorphism (AFLP) analysis and sequence-based typing (SBT) procedure. Perfectly overlapping results were obtained by both the procedures and four genotypes were identified, accounting for all the isolates. The easy transferability of the SBT data through a web-based database made it possible to identify the presence in Northern Sicily of the two SBT types most commonly circulating in Europe.