The effect of the ArF excimer laser on Candida albicans in vitro.

Candida albicans colonies in Sabouraud agar plates were irradiated with the excimer laser as follows: (a) at 10 Hz, power densities of 115-300 mJ/cm2 and 200-3000 pulses, and (b) power density of 115 mJ/cm2 and 200 pulses at 10-50 Hz. Additional colonies were irradiated with a power density of 200 mJ/cm2 at 10 Hz and 500 pulses. Each colony was cultured and the visible colony forming units were counted after 24 h. The cultures remained sterile at: 115 mJ/cm2, 1500 or 3000 pulses; 200 mJ/cm2, 400 or 500 pulses; and 300 mJ/cm2, 300 or 400 pulses. They decreased significantly in other groups. Photoablation with a power density of 115 mJ/cm2 and 200 pulses significantly decreased the number of yeast colonies in the culture plates at 30 Hz (p < 0.029) and 50 Hz (p < 0.02). Photoablation did not affect the counts in colonies located 1 or 2 mm from the treated colonies. Various energies of the excimer laser may significantly reduce or eliminate yeast in vitro.