Terapia fotodinâmica em esporos de bacillus atrophaeus e bacillus subtilis: estudos com LASER, LED, azul de metileno, rosa bengala e verde malaquita / Photodynamic therapy of spores of Bacillus atrophaeus and Bacillus subtilis: studies with laser, LED, methylene blue, rose bengal and malachite green
The spores of Bacillus spp. are found widely distributed in nature, which may cause contamination of the environment and eventually diseases to humans and animals. In response to increasing microbial resistance, photodynamic therapy (PDT) appears to act as an alternative treatment and effective. The present study aimed to compare and evaluate the action exerted by low intensity laser and green light emitting diode (LED) in spores of Bacillus atrophaeus and Bacillus subtilis in PDT, with the use of photosensitizers blue methylene (37.5 M), rose bengal (12.5 M) and malachite green (300 M). It was used a standard strain of Bacillus atrophaeus (ATCC 9372) and Bacillus subtilis (ATCC 19659). The strains were cultivated for 7 days in NutrientAgar added to 0.003% of manganese sulphate and analyzed for the formation of spores (Wirtz-Conklin staining). The spores were suspended in sterile distilled water and centrifuged for 10 min at 653 Xg. The suspensions were heat shock at 70 °C for 30 min. The suspensions were standardized to 106 cells / mL. In 96-well plates were added 0.1 ml of Bacillus subtilis or Bacillus atrophaeus and 0.1 ml of the photosensitizer or NaCl 0.9%, stirred for 5, 10 and 30 minutes and irradiated. Serial dilutions were performed. Aliquots of 0.1 mL of the dilutions were plated on BrainHeart Infusion Agar and incubated at 37 °C for 48 hours. The results were analyzed statistically (ANOVA, Tukey test, p<0.05). The highest observed reductions in CFU/ml (Log10) for Bacillus atrophaeus were 0.71 Log10 for methylene blue (10 minutes), 2.49 Log10 for rose bengal (30 min) and 0.42 Log10 for malachite green (10 min). In relation to Bacillus subtilis the largest reductions were 0.82 Log10 for methylene blue (10 minutes), 3.86 Log10 for rose bengal (30 min) and 0.63 Log10 for malachite green (10 min). The conclusion was that the PDT was effective against Bacillus subtilis and Bacillus atrophaeus the parameters tested