Low-energy shock waves improve the bacterial detection of Staphylococcus aureus biofilms on polyethylene

With the increasing number of total joint arthroplasties and the associated increase in periprosthetic infections, the further development of non-invasive examination methods to improve bacterial detection is becoming increasingly important. This is particularly important in the case of biofilm-forming bacteria, where false-negative results from joint puncture can lead to a delay in optimal therapy, as the number of planktonic bacteria in the punctate can be low. Extracorporeal shock wave therapy, originally used in the treatment of urolithiasis, has demonstrated promising energy-dependent biofilm-disrupting and even antimicrobial properties against Staphylococcus aureus. High-energy shock waves have been shown to be effective in several studies, but they are often painful and not suitable for all patients. Utilizing shock waves could enhance pathogen detection rates and potentially enable the early initiation of targeted therapy. This study therefore investigates whether low-energy shock waves are suitable for removing bacteria from a Staphylococcus aureus biofilm on polyethylene. The aim of this study is to evaluate the applicability of this method to improve the diagnostic accuracy of periprosthetic infections. In an in vitro model, Staphylococcus aureus biofilms were cultured on polyethylene patellas for 48 h. Biofilm disruption by low-energy shock waves was tested using a ReflecTron hmt device, with shock waves applied in a range of 0-1800 impulses. Colony-forming units (CFU) and XTT assays (to quantify cell viability) were measured. Shock wave treatment with an energy of 0.13 mJ/mm² proved to be effective in removing bacteria from Staphylococcus aureus biofilms on polyethylene surfaces. A significant increase in CFU within the surrounding solution was observed after just 100 impulses (p = 0.018), and continued to increase until approximately 900 impulses. A linear correlation was identified between the logarithm of the shock wave impulses and both the CFU (r = 0.971, p < 0.001) and the XTT activity (r = 0.94, p < 0.001). This finding suggests that low-energy shock waves detach living bacteria from the biofilm. Consequently, they highlight the potential of low-energy shock waves to effectively disrupt biofilms without compromising bacterial viability, reinforcing their potential diagnostic and therapeutic applications. Low-energy shock waves disrupt Staphylococcus aureus biofilms on polyethylene surfaces in vitro, dislodging bacteria from the biofilm. However, further in vivo studies are required in order to assess the potential of this method for clinical applications. Such studies could determine whether shock waves can enhance periprosthetic infection diagnosis in vivo and facilitate implant-preserving therapies for mature biofilms.