Legionella-like organisms.

The family Legionellaceae contains the new genus and species Legionella pneumophila; organisms that resemble L pneumophila but differ in one or more phenotypes are called legionella-like organisms and constitute a growing list of new species now numbering over two dozen, and the characterization of additional species of legionellae continues to expand. Similar to L pneumophila, some of these new species have additional serogroups within the species. These new species have varying degrees of clinical and epidemiological importance. We will review historical, laboratory, and clinical aspects of Legionella species other than L pneumophila and L micdadei.