Microbiological characteristics of a novel species most closely related to 'Bergeyella cardium' as a pathogen of infectious endocarditis.

Infectious endocarditis (IE) can be caused by various pathogens, from dominating agents such as viridans group streptococci and staphylococci to rare species that are less virulent and not typically considered to be pathogens. In this study, we have isolated a novel species from a patient with problem of IE which was genetically most closely related to 'Bergeyella cardium', a causative pathogen of IE first reported in Korea in 2015 as a new species of the genus Bergeyella, with a similarity of 98.8% in 16S rRNA sequences. Microbiological characteristics, including morphology, biochemical identification and antimicrobial susceptibility profiling, of this novel species were determined. This fastidious Gram-negative bacillus could only be identified successfully by molecular sequencing analysis at present, and it exhibited low minimum inhibitory concentrations to the antibiotics tested except for aminoglycosides. Phylogeny analysis revealed this novel species clustered well with 'B. cardium' and other close species of genus Bergeyella.