Evaluation of a commercial gene probe for identification of Legionella cultures.

Confirmation of a culture as Legionella when it is unreactive with available serologic reagents involves tests that are impractical in most clinical laboratories. A nucleic acid probe that hybridizes only to members of the genus Legionella was recently prepared for marketing by Gen-Probe, Inc., San Diego, Calif. We tested 215 Legionella strains, representing 22 species, and 84 non-Legionella strains, representing 17 bacterial genera, with the Gen-Probe kit. All but four Legionella strains (L. bozemanii, less than 2% of total) and no heterologous strains gave positive test results. We conclude that the Legionella gene probe is a valuable addition to existing diagnostic tests for Legionella organisms.