Effects of Q-switch Nd: YAG 1 064 nm laser on the activity and structure of staphylococcus epidermidis

Abstract

Objective: To investigate the effects of Q-switch Nd: YAG 1 064 nm laser at different energy levels on the activity and structure of staphylococcus epidermidis. Methods: Colonies of folliculitis were collected from patients, and cultured with TSA. Identification of staphylococcus epidermidis was made by gene sequencing. The staphylococcus epidermidis was cultured and irradiated by Q-switch Nd: YAG 1 064 nm laser. In the experimental group, staphylococcus epidermidis was irradiated with laser at a spot size of 2 mm diameter, pulse width ≤8 ns, and various energy levels (15.9, 19.1, 22.2, 25.4, 28.7 J/cm2), while staphylococcus epidermidis without laser treatment served as the control. The survivability and structure of staphylococcus epidermidis were evaluated by counting colony-forming unit and transmission electron microscopy, respectively. The pearson correlation analysis was used to determine the correlation of laser energy and number of colony. Results: Following irradiation with laser at energy levels of 15.9, 19.1, 22.2, 25.4, 28.7 J/cm2, colony counts were 234 500±12 554, 89 200±10 485, 52 200±6 214, 26 200±4 157, 8 300±213 CFU/mL, respectively, which were significantly lower than the control (276 400±13 150 CFU/mL) (F=1 536.97, P<0.05). Colony counts negatively correlated with laser energy levels (r=-0.90, P<0.05). In addition, laser induced a dose-dependent disruption of bacterial structure, starting at energy levels above 19.1 J /cm2. Conclusions: Q-switch Nd: YAG 1 064 nm laser can destroy the structure of staphylococcus epidermidis, and inhibit their activity.

Keywords

• q-switch nd∶yag laser
• staphylococcus epidermidis
• bacteria activity