Methods and problems of Legionella diagnosis

: 33 species of legionellae with 50 different serotypes are known. Phenotypical and biochemical similarities as well as immunologic cross-reactions impede their identification. Chemical analysis of structural features such as isoprenoidquinones, fatty acids or membrane proteins may facilitate the species classification of new isolates. A simple analytical procedure exists for ubiquinone determination. The microbiological diagnostics of legionellosis remains complex, however. Culture, direct immunofluorescence, and antigen detection in urine should be used complementary. The development of nucleic acid probes is promising but has not yet reached the stage for wide application. Serological diagnostic assays are still useful; at least in the diagnostics of non-pneumophila legionellosis the result of enzyme immunoassay and immunofluorescence should be completed by immunoblotting with distinct membrane antigens.