Genotypic and phenotypic characterization ofEnterococcus faecalisisolates from periprosthetic joint infections

Abstract

Over 2.5 million prosthetic joint implantation surgeries occur annually in the United States. Periprosthetic joint infections (PJIs), though occurring in only 1-2% of patients receiving replacement joints, are challenging to diagnose and treat and are associated with significant morbidity. The Gram-positive bacteriumEnterococcus faecalis, which can be highly antibiotic resistant and is a robust biofilm producer on indwelling medical devices, accounts for 2-11% of PJIs.E. faecalisPJIs are understudied compared to those caused by other pathogens, such asStaphylococcus aureus. This motivates the need to generate a comprehensive understanding ofE. faecalisPJIs to guide future treatments for these infections. To address this, we describe a panel ofE. faecalisstrains isolated from the surface of prosthetic joints in a cohort of individuals treated at Mayo Clinic in Rochester, MN. Here, we present the first complete genome assemblage ofE. faecalisPJI isolates. Comparative genomics shows differences in genome size, virulence factors, antimicrobial resistance genes, plasmids, and prophages, underscoring the genetic diversity of these strains. These isolates have strain-specific differences inin vitrobiofilm biomass, biofilm burden, and biofilm morphology. We measured robust changes in biofilm architecture and aggregation for all isolates when grown in simulated synovial fluid (SSF). Lastly, we evaluated antibiotic efficacy of these isolates and found strain specific changes across all strains when grown in SSF. Results of this study highlight the existence of genetic and phenotypic heterogeneity amongE. faecalisPJI isolates which will provide valuable insight and resources for futureE. faecalisPJI research.ImportancePeriprosthetic joint infections (PJIs) affect ∼1-2% of those who undergo joint replacement surgery.Enterococcus faecalisis a Gram-positive opportunistic pathogen that causes ∼10% of PJIs in the United States each year, but our understanding of how and whyE. faecaliscauses PJIs is limited.E. faecalisinfections are typically biofilm associated and can be difficult to clear with antibiotic therapy. Here, we provide complete genomes for fourE. faecalisPJI isolates from the Mayo Clinic. These isolates have strain-specific differences in biofilm formation, aggregation, and antibiotic susceptibility in simulated synovial fluid. These results provide important insight into genomic and phenotypic features ofE. faecalisisolates from PJI.