Histotripsy Treatment of <italic>S. Aureus</italic> Biofilms on Surgical Mesh Samples Under Varying Scan Parameters

Abstract

Cavitation-based ultrasound histotripsy has shown potential for treating infections on surgical mesh. The goal of this paper was to explore a new scan strategy while assessing the impact of scan speed, scan step size, and the number of cycles in the tone burst on the destruction of S. aureus biofilms grown on surgical mesh samples using ultrasound histotripsy pulses (150 MPa/-17 MPa). For each exposure, the number of colony forming units (CFUs) on the mesh and released onto the surrounding gel was quantified. Most of the exposed mesh samples had no CFUs, and there was a statistically significant reduction in CFUs on the mesh for each of the exposures, with an average reduction of 3.8 log relative to the sham. Compared with the sham, there was also a statistically significant reduction in CFUs on the gel with the highest exposures.

Impact of High-Intensity Ultrasound on Strength of Surgical Mesh When Treating Biofilm Infections

“…For the ultrasound exposures, 10 mm × 10 mm Polypropylene mesh samples (PPKM301, Surgical Mesh Division, Textile Development Associates Inc., Brookfield, CT) were inserted into Aquaflex Ultrasound Gel Pad Standoffs (Parker Laboratories Inc., Fairfield, NJ) as was done in our prior studies [9, 10]. The gel pads serve as easily reproducible sterile tissue mimics as they have approximately the same elastic modulus, ∼53 kPa, as abdominal muscle [28–30].…”

“…After insertion, the gel pad with the mesh was placed inside an aluminum holder inside a water tank. The focus of the ultrasound transducer was then aligned on the mesh sample using a low-power signal from a pulser-receiver (Panametrics 5900, Olympus Corporation, Tokyo, Japan) as was done previously [9, 10]. The mesh samples were then exposed to either a sham exposure or a series of high-intensity ultrasound pulses.…”

“…Once the biofilm has been destroyed, any surviving planktonic bacteria will be susceptible to traditional antibiotic treatment. Prior studies successfully destroyed Escherichia coli ( E. coli ), Pseudomonas aeruginosa ( P. aeruginosa ), and Staphylococcus aureus ( S. aureus ) biofilms [7–10].…”

“…More recently, the studies have focused on treating S. aureus biofilms on surgical mesh samples [9, 10] due to the prevalence of S. aureus infections following hernia repair [15–17]. Infections on surgical mesh are one of the most significant complications and require mesh removal ∼70% of the time with a significant risk of hernia reoccurrence following mesh removal [15–19].…”

For Whom the Bubble Grows: Physical Principles of Bubble Nucleation and Dynamics in Histotripsy Ultrasound Therapy

“…However, histotripsy has the potential to be utilized in disease pathologies that would otherwise require surgical intervention Duryea et al 2011;Hall et al 2007b;Hempel et al 2011;Khokhlova et al 2014;Kim et al 2013Kim et al , 2014aMaxwell et al 2011a;Owens et al 2010;Schade et al 2015;Styn et al 2010;Vlaisavljevich et al 2013bVlaisavljevich et al , 2016cZhang et al 2017). Pre-clinical studies have investigated histotripsy for the treatment of thrombus obstruction (Bader et al 2016a;Maxwell et al 2011a;Sukovich et al 2017;Zhang et al 2017), fetal septal defects (Xu et al 2010), kidney stones (Duryea et al 2014), hepatocellular carcinoma (Khokhlova et al 2014;Vlaisavljevich et al 2013cVlaisavljevich et al , 2017b, renal carcinoma (Roberts et al 2006), transcranial ablation (Sukovich et al 2016) and biofilms (Bigelow et al 2018), amongst others (Khokhlova et al 2015). Furthermore, a clinical trial was recently completed whose primary outcome was to assess the safety of histotripsy technology to treat benign prostatic hyperplasia (Schuster et al 2018).…”