Human urinary extracellular vesicle preparations inhibit in vitro biofilm formation against several uropathogens

Urinary tract infections (UTIs) rank as one of the most frequent bacterial infections globally, with multiple bacterial species such as uropathogenic Escherichia coli (UPEC), Klebsiella pneumoniae, and Pseudomonas aeruginosa being significant causative agents that can develop biofilms associated with antimicrobial resistance (AMR) and recurrence. Urinary extracellular vesicles (UEVs) are nanosized particles secreted by cells lining the urinary tract which carry nucleic acid and protein cargo, including antibacterial proteins, and high concentrations of UEVs exert antibacterial activity against UPEC in vitro. This study investigated the antibiofilm potential of UEVs against biofilm-forming uropathogens.

UEV preparations from healthy human volunteers were added to bacteria, and biofilm formation was assessed using safranin-based biofilm quantification.

UEV preparations from the majority of volunteers significantly inhibited biofilm formation of multiple uropathogens, including UPEC (66.2% [34.8%-85.6%] inhibition vs. control), P. aeruginosa (37.2% [5.8%-42.6%]), and K. pneumoniae (31.8% [18.0%-60.4%]), an effect evident at physiologically relevant concentrations. UEV concentrations that exhibited antibiofilm activity were also not sufficient to inhibit bacterial growth.

These findings highlight the potential role of UEVs as innate modulators of uropathogen biofilms and lay the groundwork for future exploration of the relevance of host-derived UEVs in determining risks of recurrent UTIs.