Histotripsy Treatment of Microbial Biofilms in Clinical Urinary Catheters: A Pilot Study

Indwelling urinary catheters frequently develop intraluminal biofilms, increasing the risk of catheter-associated urinary tract infections and systemic infections. Current prophylactic strategies, including antibiotics and antimicrobial coatings, have not consistently reduced the risk of infection. Histotripsy, a focused ultrasound ablation method, offers a promising non-invasive approach to mechanically disrupt biofilms and has demonstrated efficacy against catheter-associated biofilms in vitro. This study evaluated the ability of histotripsy to disrupt clinically derived intraluminal biofilms. Explanted urinary catheters were segmented and treated ex vivo with histotripsy, with matched untreated segments serving as controls. Following treatment, catheter segments were assessed for microbial viability by culture and for biofilm biomass using a crystal violet assay. Three silicone catheters were collected, each with four treated and four matched control segments. Based on Gram stain morphology, the three catheter tip cultures were consistent with Staphylococcus aureus, mixed Gram-positive and Gram-negative organisms, and a budding yeast suggestive of a Candida species, respectively. A single histotripsy treatment with a pulse repetition frequency of 200 Hz and estimated peak negative pressure of 31.6 MPa resulted in an 81.7% reduction in biofilm biomass compared with untreated controls (p < 0.001). Viable organisms remained detectable after treatment under the tested parameters.  These findings support further investigation of histotripsy as an approach for managing catheter-associated biofilm infections. Additional studies are needed to optimize treatment parameters and explore potential clinical applications.