Immunofluorescence characterization of Legionella: narrow specificity of polyclonal immunsera to various serogroups and species.

This study was to determine by direct fluorescent antibody staining with antibodies prepared in rabbits, the degree of cross-reactions between serogroups of Legionella pneumophila (1 to 6) and the other antigenic species of Legionella (L. bozemanii, L. dumoffii, and L. micdadei), in order to increase the accuracy of diagnosis and to allow us to reduce the number of conjugates. The polyclonal antibodies were highly species and serogroup-specific without absorption for characterization of Legionella either in patient specimens or in isolated cultures by direct fluorescent antibody staining. No cross-reaction was observed with non-legionella bacteria isolated from sputum specimens. A battery of conjugates for different serogroups and species is necessary for increasing the accuracy of diagnosis of legionellosis.