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Legionella cardiaca sp. nov., isolated from a case of native valve endocarditis in a human heart

MM Pearce, N Theodoropoulos... - ... of Systematic and ..., 2012 - Soc General Microbiol Abstract A Gram-negative, rod-shaped bacterium, designated H63T, was isolated from the aortic valve tissue of a patient with native valve endocarditis. 16S r RNA sequencing revealed that H63T belongs to the genus Legionella with its closest neighbors being ... [CITATION] 190 Surgery of infective endocarditis analyzed within a one-year population-based study F Delahaye, C Suty-Selton, B Iung... - Archives of ..., 2012 - Elsevier

A Gram-negative, rod-shaped bacterium, designated H63T, was isolated from the aortic valve tissue of a patient with native valve endocarditis. 16S r RNA sequencing revealed that H63T belongs to the genus Legionella with its closest neighbors being Legionella brunensis (98.8%), Legionella londiniensis (97.0%), Legionella jordanis (96.8%), Legionella erythra (96.2%), Legionella dresdenensis (96.0%), and Legionella rubrilucens, Legionella feeleii, Legionella pneumophila and Legionella birminghamensis (95.7%). DNA-DNA hybridization values indicated that H63T is < 70% similar to its nearest 16S r RNA neighbors, documenting that the strain is a novel species. Phylogenetic analysis of the 16S r RNA, macrophage infectivity potentiator (mip), and R Nase P (rnp B) genes confirmed that H63T is a distinct species, with L. brunensis being its closest sister taxon. Fatty acid composition and biochemical traits, such as the inability to ferment glucose and reduce nitrate, supported the affiliation of H63T to the genus Legionella. H63T was distinguishable from its neighbors based on it being hippurate-hydrolysis positive and oxidase negative. H63T was further differentiated by its inability to grow on BCYE agar at 170C, poor growth on low-iron media, and lack of sliding motility. Also, H63T did not react with antisera generated from Legionella species type strains. H63T replicated within macrophages. It also grew in mouse lungs, inducing histopathologic evidence of pneumonia and dissemination to the spleen. Together, these results confirm that H63T is a novel, pathogenic Legionella species for which the name Legionella cardiaca sp. nov. (type strain H63T =ATCC BAA-2315 = DSM 25049 = JCM 17854) is proposed.