aluminum-phthalocyanine-disulfonate and gallium-arsenide

Suspensions of Streptococcus mutans, S. sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a gallium aluminium arsenide laser in the presence of aluminium disulphonated phthalocyanine and the numbers of survivors determined. Exposure to the laser light in the absence of the dye, or the dye in the absence of the laser light, had no significant effect on the viability of the organisms. However, a light-dose-related decrease in the viable count of all four target organisms was found on exposure to the laser light in the presence of the dye. The kills attributable to lethal photosensitization amounted to approximately 10(6) CFU in the case of each organisms. As appreciable kills were achieved within clinically convenient exposure times (30-90 s), these results imply that lethal photosensitization may be a useful technique for eliminating bacteria from carious lesions prior to restoration.

Topics: Actinomyces viscosus; Arsenicals; Bacteria, Anaerobic; Colony Count, Microbial; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Gallium; Indoles; Lacticaseibacillus casei; Lasers; Microbial Sensitivity Tests; Organometallic Compounds; Photosensitizing Agents; Streptococcus mutans; Streptococcus sobrinus

The purpose of this study was to determine whether Candida albicans, and other Candida spp. responsible for HIV-associated candidosis, could be sensitised to killing by low-power laser light. Suspensions of C. albicans were treated with a number of potential photosensitisers, exposed to laser light from a Helium/Neon (HeNe) or Gallium aluminium arsenide (GaAs) laser for 120 s and survivors enumerated. Toluidine blue O (TBO), thionin and crystal violet were able to sensitise the yeast to killing by light from the HeNe laser (energy dose = 876 mJ at a density of 66.36 J/cm2), the kills achieved being 6.8 x 10(6) cfu/ml, 3.1 x 10(6) cfu/ml and 1.3 x 10(6) cfu/ml respectively. TBO was also able to sensitise several other Candida spp. to killing by HeNe laser light. Dihaematoporphyrin ester was not an effective photosensitiser under the conditions employed. Methylene blue, but not aluminium disulphonated phthalocyanine, was able to sensitise C. albicans to killing by light from the GaAs laser (energy dose 1.32 J at a density of 2.04 J/cm2). The viability of the yeast was not affected by exposure to laser light in the absence of the photosensitisers. As killing of dye-sensitised C. albicans, and other Candida spp., could be achieved by exposure to low-power laser light for short periods of time, this approach merits further investigation as a potential therapeutic modality for HIV-associated candidosis.

Topics: Aluminum; Arsenicals; Candida; Candida albicans; Colony Count, Microbial; Dihematoporphyrin Ether; Gallium; Gentian Violet; Helium; Indoles; Lasers; Methylene Blue; Neon; Organometallic Compounds; Phenothiazines; Photosensitizing Agents; Phototherapy; Radiation-Sensitizing Agents; Tolonium Chloride