Immunoperoxidase Staining for the Serotype-Specific Demonstration of Legionella pneumophila

To the Editor: We have developed direct and indirect immunoperoxidase staining methods for the demonstration of four serotypes of Legionella pneumophila and have applied these techniques to stain the organisms in smears from cultures, sputum specimens, and formalin-fixed, paraffin-embedded lung sections. The following four strains of Legionella pneumophila were obtained from the Centers for Disease Control: Philadelphia 1 (serogroup 1), Togus 1 (serogroup 2), Bloomington 2 (serogroup 3), and Los Angeles 1 (serogroup 4). Antibodies to these strains were prepared in hyperimmune mouse ascites fluid, with whole, formalinized organisms as the immunogen. The gamma-globulin fractions from these fluids were isolated.