Evaluation of antimicrobial photodynamic therapy with erythrosine and blue light emitting diode for inactivation of Aggregatibacter actinomycetemcomitans.

This study aims to analyze the effect of antimicrobial photodynamic therapy on Aggregatibacter actinomycetemcomitans using erythrosine as a photosensitizer and a blue light emitting-diode as a light source. Inoculum samples of A. actinomycetemcomitans with PBS were used in each of the groups, being the control group (C); light group (L) corresponding to light emitting-diode irradiation for 300 s; photosensitizing group (0) without irradiation; and the aPDT groups with different irradiation times (aPDT20) with 20s of irradiation; (aPDT40) with 40s of irradiation; (aPDT60) with 60s of irradiation; (aPDT180) with 180s; and (aPDT300) with 300s. Samples were used to determine colony forming units (CFU). Aliquots of 10 µL were plated through six serial dilutions on brain-heart infusion agar in Petri dishes. The plates were incubated at 37 °C for a period of up to 24-48 h under microaerophilic conditions to evaluate the total bacteria recovered. After this period, CFUs were counted, and the data was subjected to one-way analysis of variance. When aPDT was performed for 180 and 300 s, the mean log10 (CFU/ml) was equal to 0. In the aPDT60 group, a significant yet incomplete microbial reduction was observed. SEM images confirmed that membrane integrity was maintained, indicating that aPDT induced cellular alterations without causing membrane disruption. Antimicrobial photodynamic therapy employing erythrosine as a photosensitizer and blue light emitting-diode light-curing unit for composite resin polymerization used in dental practices demonstrated significant antimicrobial efficacy against A. actinomycetemcomitans, a principal pathogen in periodontitis, under the evaluated experimental conditions.