Legionella isolates recovered in 21 different Spanish provinces over 8 years from both clinical (67 isolates) and environmental (181) samples, mostly from case-associated buildings, are described: 92·5% of clinical isolates were L. pneumophila serogroup 1 (SGI), only five isolates belonging to other species or serogroups: two L. pneumophila SG6, two SG8 and one L. bozemanii SG1 not clearly related with clinical infection.
L. pneumophila SG1 accounted for 53·6% of isolates from the environment, followed by SG8 (27·6%). SG3 (9·4%) and SG6 (7·2%). Three isolates were labelled as SG8/10.
Subtyping of L. pneumophila SG1 by the standardized panel of monoclonal antibodies revealed 90·3% of clinical and 78·3% of environmental isolates as belonging to Pontiac subgroup. Pontiac isolates were further divided into 55·3% Philadelphia 1 or Allentown 1, 21·9% Benidorm 030E and 20·4% Knoxville 1.
Characterization of samples from four outbreaks in which both clinical and environmental isolates had been recovered permitted the recognition of three Philadelphia 1 or Allentown 1 and one Knoxville 1 strains as the aetiological agents.