Occurrence and distribution of sequence types among Legionella pneumophila strains isolated from patients in Germany: common features and differences to other regions of the world

A total of 105 unrelated clinical isolates of Legionella pneumophila were randomly selected from the German National Legionella strain collection and typed by monoclonal antibody (MAb) subgrouping and a seven-gene locus sequence-based typing (SBT) scheme. According to the case definitions of the European Working Group for Legionella Infections, 19 of the isolates tested were travel-associated, 38 were community-acquired and 48 were of nosocomial origin. Eighty-four of these strains belonged to serogroup 1, 20 belonged to other serogroups, and one isolate could not be serogrouped. The majority of strains among the travel-associated and community-acquired cases were MAb3-1-positive. The most common sequence type (1, 4, 3, 1, 1, 1, 1) was found in 20 isolates in 11 cities; other allelic profiles also found in Europe (2, 3, 9, 10, 2, 1, 6), (1, 3, 9, 10, 2, 1, 6), (2, 6, 17, 14, 13, 11, 11) and (3, 4, 1, 1, 1, 9, 1) were detected among the German isolates but at a low frequency. In contrast, some SBT are unique to Germany, including (3, 4, 1, 3, 35, 9, 11), which was found among five isolates from patients in Berlin. In concordance with European data, a significant portion of the L. pneumophila strains isolated from patients in Germany belong to clones that occur throughout the world and which are responsible for the majority of clinical cases.