Enterococcus faecalis Polymicrobial Interactions Facilitate Biofilm Formation, Antibiotic Recalcitrance, and Persistent Colonization of the Catheterized Urinary Tract

Abstract

Indwelling urinary catheters are common in health care settings and can lead to catheter-associated urinary tract infection (CAUTI). Long-term catheterization causes polymicrobial colonization of the catheter and urine, for which the clinical significance is poorly understood. Through prospective assessment of catheter urine colonization, we identified <i>Enterococcus faecalis</i> and <i>Proteus mirabilis</i> as the most prevalent and persistent co-colonizers. Clinical isolates of both species successfully co-colonized in a murine model of CAUTI, and they were observed to co-localize on catheter biofilms during infection. We further demonstrate that <i>P. mirabilis</i> preferentially adheres to <i>E. faecalis</i> during biofilm formation, and that contact-dependent interactions between <i>E. faecalis</i> and <i>P. mirabilis</i> facilitate establishment of a robust biofilm architecture that enhances antimicrobial resistance for both species. <i>E. faecalis</i> may therefore act as a pioneer species on urinary catheters, establishing an ideal surface for persistent colonization by more traditional pathogens such as <i>P. mirabilis</i>.