SEQUENCE-BASED CLASSIFICATION SCHEME FOR THE GENUS LEGIONELLA TARGETING THE MIP GENE

The identification and speciation of strains of Legoniella is often di fficult, and even the more successful chromatographic classification t echniques have struggled to discriminate newly described species. A se quence-based genotypic classification scheme is reported, targeting ap proximately 700 nucleotide bases of the mip gene and utilizing gene am plification and direct amplicon sequencing. With the exception of Legi onella geestiana, for which an amplicon was not produced, the scheme c learly and unambiguously discriminated among the remaining 39 Legionel la species and correctly grouped 26 additional serogroup and reference strains within those species. Additionally, the genotypic classificat ion of approximately 150 mild strains from several continents was cons istent with their phenotypic classification, with the exception of a f ew strains where serological cross-reactivity was complex, potentially confusing the latter classification. Strains thought to represent cur rently uncharacterized species were also found to be genotypically uni que. The scheme is technically simple for a laboratory with even basic molecular capabilities and equipment, if access to a sequencing labor atory is available.