Rapid Identification of Clinically Relevant Legionella spp. by Analysis of Transfer DNA Intergenic Spacer Length Polymorphism

Abstract

ABSTRACT Analysis of PCR-amplified transfer DNA (tDNA) intergenic spacers was evaluated as a rapid method for identification to the species level of 18 species of Legionella known as human pathogens. Type strains ( n = 19), reference strains ( n = 16), environmental strains ( n = 31), and clinical strains ( n = 32) were tested. PCR products using outwardly directed tDNA consensus primers were separated on polyacrylamide gels and analyzed with automated laser fluorescence. Test results were obtained in 8 h starting with 72-h-old bacterial growth on solid medium. Species-specific patterns were obtained for all 18 Legionella species tested: Legionella anisa , L. bozemanii serogroups 1 and 2, L. cincinnatiensis , L. dumoffii , L. feeleii serogroups 1 and 2, L. gormanii , L. hackeliae serogroups 1 and 2, L. jordanis , L. lansingensis , L. longbeachae serogroups 1 and 2, L. lytica , L. maceachernii , L. micdadei , L. oakridgensis , L. parisiensis , L. pneumophila serogroups 1 to 14, L. sainthelensi serogroup 2, L. tucsonensis , and L. wadsworthii . Computer-assisted matching of tDNA-intergenic length polymorphism (ILP) patterns identified all 63 environmental and clinical strains to the species level and to serogroup for some strains. tDNA-ILP analysis is proposed as a routinely applicable method which allows rapid identification of environmental and clinical isolates of Legionella spp. associated with legionellosis.