Rapid demonstration of Legionella pneumophila in unembedded tissue. An adaptation of the Giménez stain.

The Giménez stain, originally developed for demonstrating rickettsiae, readily stained the Legionnaires' disease bacterium (Legionella pneumophila) in frozen tissue sections and smears of fresh or formalin-fixed lung tissue from patients who had confirmed Legionnaires' disease. With the Giménez procedure, the bacterium stained bright red against a blue-green background. The tissue Gram procedures also stained L. pneumophila in frozen sections and smears, but the staining reaction was weak, and these stains were neither as sensitive nor a consistent as the Giménez procedure.