Investigation of shockwave treatment for disruption of bacterial biofilm on tubular structure

Biofilms, which are structures formed by microorganisms, are protected by extracellular polymeric substances (EPS) secreted by bacteria against external threats, including antibiotics. The current study aims to assess the effects of shockwave treatment combined with antibiotic therapy on Pseudomonas aeruginosa biofilms in tubular structures in vitro. The biofilms were formed on the inner surfaces of silicone tubes for three days under dynamic conditions. The biofilms were treated with shockwave treatment (120 pulses at 2 Hz), followed by exposure to 4 µg/ml ciprofloxacin for 6 h. Bacterial viability was assessed using colony-forming unit (CFU) and confocal laser scanning microscopy (CLSM) with SYTO9/PI staining, while biofilm detachment was evaluated via crystal violet (CV) staining and scanning electron microscopy (SEM). According to the SEM and CFU analysis, the shockwave and antibiotic-combined treatment significantly detached the biofilm, removing up to 97.5% of the surface area and decreased bacterial viability by 40%, compared to untreated control biofilms. The CV staining showed a significant reduction in biofilm biomass to an OD₆₀₀ of 0.14. The CLSM analysis revealed a dead bacteria proportion of 67%. In conclusion, the shockwave treatment combined with antibiotics could effectively degrade the biofilms in tubular structures and enhance antibiotic efficacy.