Genetic and functional enrichments associated with Enterococcus faecalis isolated from the urinary tract

Abstract

ABSTRACTEnterococcus faecalis is the leading Gram-positive bacterial species implicated in urinary tract infection (UTI). An opportunistic pathogen, E. faecalis is a commensal of the human gastrointestinal tract (GIT), and its presence in the GIT is a predisposing factor for UTI. How E. faecalis colonizes and survives in the urinary tract (UT) is poorly understood, especially in uncomplicated or recurrent UTI. The UT is distinct from the GIT and is characterized by a sparse nutrient landscape and unique environmental stressors. In this study, we isolated and sequenced a collection of 37 clinical E. faecalis strains from the urine of primarily postmenopausal women. We generated 33 closed genome assemblies and 4 highly contiguous draft assemblies and conducted a comparative genomics analysis study to identify genetic features enriched in urinary E. faecalis with respect to E. faecalis isolated from the human GIT and blood. Phylogenetic analysis revealed high diversity among urinary strains and a closer relatedness between urine and gut isolates than blood isolates. Plasmid replicon (rep) typing further underscored possible UT-GIT interconnection, identifying nine shared rep types between urine and gut E. faecalis. Both genotypic and phenotypic analyses of antimicrobial resistance among urinary E. faecalis revealed infrequent resistance to the front-line UTI antibiotics nitrofurantoin and fluoroquinolones and no vancomycin resistance. Finally, comparing gene presence and absence among urinary and gut strains, we identified 19 candidate genes enriched among urinary strains. These genes are involved in the core processes of sugar transport, cobalamin import, glucose metabolism, and post-transcriptional regulation of gene expression.IMPORTANCEUrinary tract infection (UTI) is a global health issue that imposes a substantial burden on healthcare systems. Women are disproportionately affected by UTI, with >60% of women experiencing at least one UTI in their lifetime. UTIs can recur, particularly in postmenopausal women, leading to diminished quality of life and potentially life-threatening complications. Understanding how pathogens colonize and survive in the urinary tract is necessary to identify new therapeutic targets that are urgently needed due to rising rates of antimicrobial resistance. How Enterococcus faecalis, a bacterium commonly associated with UTI, adapts to the urinary tract remains understudied. Here, we generated a collection of high-quality closed genome assemblies of clinical urinary E. faecalis isolated from the urine of postmenopausal women that we used alongside detailed clinical metadata to perform a robust comparative genomic investigation of genetic factors that may be involved in E. faecalis survival in the urinary tract.

Keywords

• urinary tract infection
• host-microbe interactions
• adaptation
• genomics
• hybrid assembly
• Enterococcus