The bactericidal effect of continuous wave laser with strongly absorbing coating at the fiber tip

The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied. Gram-negative rod Escherichia coli and the Gram-positive coccus Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium were used in this study. Each bacterial species was treated by continuous-wave near infrared laser coupled with bare fiber tip or strongly absorption coating fiber tip. After treatment, the temperature of bacterial suspension was measured. In addition, the temperature distribution was analyzed. It has been shown that using laser with a strongly absorption coating fiber tip results in significant bactericidal effect. The decrease of the amount of E. coli and S. epidermidis was 100% after treatment with an output power of 6W of radiation at a wavelength of 0.97μm for 40s. Number of S. aureus and Ent. faecium colony-forming unit was reduced to 70% after same exposure. The peak temperature of bacterial suspension was 86∘C after treatment by laser with a strongly absorption coating fiber tip. Laser with a strongly absorption coating fiber tip provides large-scale hydrodynamic flows directed away from the fiber tip. The laser with a strongly absorption coating fiber tip has bactericidal effect. The main role is associated with the effect of high temperature, which, in the form of flow in a liquid medium, affects bacteria