Mobile DNA and multiple drug resistance in Enterococcus faecalis: How did it come to this?

ITQB Seminar

Title: Mobile DNA and multiple drug resistance in Enterococcus faecalis: How did it come to this?

Speaker: Kelli Palmer

Affiliation: Post-Doc research Fellow; The Schepens Eye Research Institute, Harvard Medical School

Host: Fátima Lopes-Antibiotic Stress and Virulence of Enterococci Laboratory

Abstract:

Mobile DNA and multiple drug resistance in Enterococcus faecalis: How did it come to this?

Kelli Palmer1,2, Dirk Gevers3, Michael Feldgarden3 and Michael Gilmore1,2

Schepens Eye Research Institute, Boston, MA1; Department of Ophthalmology, Harvard Medical School,
Boston, MA2; Broad Institute, Cambridge, MA3.

Enterococcus faecalis is a promiscuous bacterium, with lifestyles ranging from benign commensal to hospitalacquired
pathogen. In addition to virulence factor production, some E. faecalis strains are notorious for
carriage of multiple antibiotic resistances, and for the propensity to disseminate resistance determinants to
other pathogens such as methicillin-resistant Staphylococcus aureus. The acquisition and dissemination of
novel traits by E. faecalis that enhance virulence, antibiotic resistance, and survival in clinical environments are
of great concern. To gain a greater understanding for the content of the E. faecalis pan genome, and to
evaluate E. faecalis genome stability on a large scale, the genomes of fifteen E. faecalis isolates of different
multi-locus sequence types were sequenced in collaboration with the Broad Institute of Cambridge, MA.
Pairwise analysis of these genomes reveals that the E. faecalis isolates are phylogenetically closely related, as
judged by percent nucleotide identity in core genes, but vary widely in overall gene content. The genomes host
a myriad of putative mobile elements including putative phage, plasmids, and transposons containing genes of
diverse phylogenetic origins and predicted functions. The recently described Clustered, Regularly Interspaced,
Short Palindromic Repeats system (CRISPR) confers protection from attack by foreign DNA and acts as an
acquired immune defense system in prokaryotes; E. faecalis possesses disparate CRISPR locus content from
strain to strain. Strikingly, complete CRISPR loci are absent from most clinical isolates collected after 1975.
Presented is an overview of this comparative genome analysis and a discussion of the relationship between E.
faecalis genome stability, antibiotic resistance, and CRISPR content.