Avaliação da atividade antimicrobiana do complexo de rutênio RuCL(dppb) NO2 foto ativado contra bactérias relacionadas à infecções endodônticas

Abstract

Bacteria have a natural tendency to develop communities of cells surrounded by a polysaccharide matrix called a biofilm. Biofilms are formed on the surfaces of teeth (dental plaque) and are the main etiologic factor for most dental problems such as caries, gingivitis, periodontitis and endodontic infections. Regarding endodontic infections, bacteria are the main agents causing pulp and periapical alterations, being responsible for the high incidence of root canal retreatment in the dental clinic, with the species Enterococcus faecalis, the main agent causing this type of impairment. In this context, the search for new compounds capable of preventing or eradicating oral biofilms was intensified with these bacteria. This study aimed to evaluate the antimicrobial activity of the ruthenium complex [RuCl(dppb)(NO)2] with and without irradiation of blue LED light (463 nm) on the bacteria Enterococcus faecalis ATCC 10100 and Enterococcus faecalis ATCC 19433. Antibacterial activity was determined by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm effect was determined using the crystal violet (CV) and viable cell count (CFU) method, both for inhibition of biofilm formation and for preformed biofilms. In 96-well microtiter plates, the bacteria were seeded at different concentrations of the complex (125 to 1.9 μg/mL), and incubated for 24 h at 37°C under atmospheric pressure, with 5% CO2. The results showed that [RuCl(dppb)(NO)2] complex, when irradiated by light, presented MIC of 3.9 μg/mL, and CBM between 3.9 and 7.8 μg/mL, for both bacteria, in the however, in the absence of light, MIC values were between 7.8 and 15.6 μg/mL and CBM between 15.6 and 31.2 μg/mL. With regard to biofilm formation, in general, the complex inhibited between 81 and 100% the formation of biomass and the number of viable cells was reduced between 1 and 4.7 log CFU/mL. For pre-formed biofilms of both species, there was a reduction in biomass between 15 and 97% and a decrease in the number of CFUs between 1and 2 log. It was concluded that the complex [RuCl(dppb)(NO)2] is a possible potential antimicrobial in the control of microbial growth and in the reduction of oral biofilms involving the species Enterococcus faecalis.