Clonality of Enterococcus faecalis isolates from infective endocarditis patients at a Danish hospital
Abstract number: P2119
Larsen J., Chadfield M.S., Schønheyder H.C., Bisgaard M.
Objectives: To investigate the clonality of Enterococcus faecalis isolates from infective endocarditis (IE) patients at Aalborg Hospital in Denmark. The issues addressed include the apparent contradiction between the ability to cause IE and the presumed poor selective advantages as such infections often lead to rapid host death and poor transmission to new hosts.
Methods: For this study, we used 27 E. faecalis isolates from patients with definite IE according to the modified Duke criteria. These isolates were collected prospectively over a 7-year period from 1996 to 2002 at Aalborg Hospital in Denmark. The clonality of the isolates was inferred by using multilocus sequence typing (MLST).
Results: The MLST data revealed 15 sequence types (STs) among the 27 isolates. Fourteen isolates clustered in 6 groups of single-locus variants (SLVs), of which 10 were members of clonal complexes (CC40, CC21, and CC25), whereas 13 isolates clustered in 7 singleton STs. CC25 (8 isolates) appears to be a high-risk enterococcal clonal complex associated with human bloodstream infections in Europe, whereas CC40 (1 isolate) and CC21 (1 isolate) exhibit larger ecologic diversity according to their host and geographic origin, and commensalism/virulence traits.
Conclusion: The results demonstrated surprising diversity among E. faecalis isolates causing IE, despite their narrow time-span and geographic range. The virulence trait was randomly distributed within E. faecalis, supporting the idea that virulence might be coincidental to a commensal lifestyle. However, it is also possible that horizontal gene transfer of virulence-related factors has lead to the emergence of clonal complexes (i.e., CC25) associated with an increased ability to cause IE. This work will allow further epidemiological, genetic, and phenotypic studies devoted to test how virulence evolves in E. faecalis.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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