Laser Disruption of Biofilm

Abstract

To demonstrate the capability of a fiber-based Q-switched Nd:YAG laser (ARCLaser, Nuremberg, Germany and Valam, Orangeburg, NY) to disrupt biofilm. Biofilms were grown in broth for 72 hours prior to the experiment. A clinical otorrhea isolate from Pseudomonas aeruginosa was used. Biofilms were placed in MatTek culture plates, on stainless steel screws, tympanostomy tubes, and polyethylene terephthalate (PET) sutures. Culture plates, stainless steel screws, tympanostomy tubes, and PET sutures were used for the laser disruption of biofilm experiments. Q-switched Nd:YAG laser pulses were delivered on biofilms using shockwave probes originally designed for cataract surgery. The thin laser fiber tip was targeted against a titanium target, creating the production of plasma and resulting in a shockwave effect. Biofilm areas were imaged before, during, and after laser application using a confocal microscope. The biofilm was imaged growing on the glass/plastic step of the plates, in the grooves of the threads of the screws, over the tympanostomy tube, and on the PET suture. During laser treatment, a time-lapse function was used to capture the results. As a result of laser-generated shockwaves, the biofilm was initially seen to oscillate and eventually break off with individual pulses. Large and small pieces of biofilm were totally and instantly removed from the surface to which they were attached in a matter of a few seconds. We were able to effectively disrupt Pseudomonas aeruginosa biofilms in vitro using a miniature Q-switched Nd:YAG laser, thin fibers, and special probes that generated plasma formation and a resulting shockwave effect. This laser technology has the ability to generate a powerful stress wave sufficient to disrupt biofilm without any ill effect to the underlying host structure.