ABSTRACTLegionellais ubiquitous in many environments. At least 50 species and 70 serogroups of the Gram-negative bacterium have been identified. Of the 50 species, 20 are pathogenic, andLegionella pneumophilais responsible for the great majority (approximately 90%) of the Legionnaires' disease cases that occur. Furthermore, of the 15L. pneumophilaserogroups identified, O1 alone causes more than 84% of the Legionnaires' disease cases that occur worldwide. Rapid and reliable assays for the detection and identification ofL. pneumophilain water, environmental, and clinical samples are in great demand.L. pneumophilabacteria are traditionally identified by their O antigens by immunological methods. We have recently developed an O serogroup-specific DNA microarray for the detection of all 15 distinct O-antigen forms ofL. pneumophila, including serogroups O1 to O15. A total of 35 strains were used to verify the specificity of the microarray, including 15L. pneumophilaO-antigen standard reference strains and sevenL. pneumophilaclinical isolates as target strains, seven reference strains of other non-pneumophila Legionellaspecies as closely related strains, and six non-Legionellabacterial species as nonrelated strains. The detection sensitivity was 1 ng of genomic DNA or 0.4 CFU/ml in water samples with filter enrichment and plate culturing. This study demonstrated that the microarray allows specific, sensitive, and reproducible detection ofL. pneumophilaserogroups. To the best of our knowledge, this is the first report of a microarray serotyping method for all 15 distinct O-antigen forms ofL. pneumophila.
Detection and Identification of Mycobacterium Species Isolates by DNA Microarray