A newly identified bacterium phenotypically resembling, but genetically distinct from, Legionella pneumophila: an isolate in a case of pneumonia.

A bacterium with growth characteristics similar to, but genetically distinct from, either Legionella pneumophila or WIGA (a "rickettsia-like agent") was obtained from a postmortem lung specimen of a patient with fatal atypical pneumonia at the M. D. Anderson Hospital and Tumor Institute in Houston, Texas. This bacterium and WIGA have essentially the same cellular fatty acid composition, which is distinct from that of L. pneumophila. Deoxyribonucleic acid-reletadness studies show that the isolate from Texas is only about 10% related to both L. pneumophila and WIGA and there fore may represent a new species. This new bacterium should be considered in selecting laboratory procedures in the diagnosis of atypical pneumonia.