Aerococcus urinae is increasingly recognized as a potentially significant urinary tract bacterium. A. urinae has been isolated from urine collected from both males and females with a wide range of clinical conditions, including urinary tract infection (UTI), urgency urinary incontinence (UUI), and overactive bladder (OAB). A. urinae is of particular clinical concern because it is highly resistant to many antibiotics and, when undiagnosed, can cause invasive and life-threatening bacteremia, sepsis, or soft tissue infections. Previous genomic characterization studies have examined A. urinae strains isolated from patients experiencing UTI episodes. Here, we analyzed the genomes of A. urinae strains isolated as part of the urinary microbiome from patients with UUI or OAB. Furthermore, we report that certain A. urinae strains exhibit aggregative in vitro phenotypes, including flocking, which can be modified by various growth medium conditions. Finally, we performed in-depth genomic comparisons to identify pathways that distinguish flocking and nonflocking strains.

IMPORTANCE Aerococcus urinae is a urinary bacterium of emerging clinical interest. Here, we explored the ability of 24 strains of A. urinae isolated from women with lower urinary tract symptoms to display aggregation phenotypes in vitro. We sequenced and analyzed the genomes of these A. urinae strains. We performed functional genomic analyses to determine whether the in vitro hyperflocking aggregation phenotype displayed by certain A. urinae strains was related to the presence or absence of certain pathways. Our findings demonstrate that A. urinae strains have different propensities to display aggregative properties in vitro and suggest a potential association between phylogeny and flocking.