Rapid presumptive bacteriological diagnosis of Legionnaires disease.

A simple, relatively rapid silver impregnation stain has been found to stain Legionella pneumophila effectively in paraffin-embedded tissue sections while permitting visualization of histological detail. It may also be used to stain the organism in body fluids. The stain is not specific and thus must be confirmed by direct fluorescent-antibody technique or culture, but, in the absence of other bacilli demonstrable by Gram or other stain, visualization of typical bacillary forms in a patient with illness compatible with Legionnaires disease provides strong presumptive evidence supporting this diagnosis.