Plasmid profiles of Legionella pneumophila strains isolated in Spain

An assay for plasmid DNA content was carried out in 100 strains of Legionella pneumophila of distinct serogroups and isolated from various sources (clinical, environment). The strains were isolated from different geographic regions in our country. The presence of plasmids was proved in one of the 11 clinical isolates and in 68 of the 89 isolated of environmental origin studied. In the strains belonging to serogroup 1 and isolated in our region (Cantabria), three plasmid profiles were observed, whereas in strains of the same serogroup from other geographic regions, two profiles were shown which exhibited differences compared to the former ones. Analysis by means of restriction endonucleases suggested that plasmids of similar size in serogroup 1 strains of different source, were related. The results obtained do not appear to reveal any correlation between plasmid profile and source of isolation or serogroup.