Atividade de extratos de Erythrina spp. sobre o crescimento populacional e a formação de biofilme de Streptococcus do grupo mutans

Abstract

Biofilms represent an important survival strategy for microorganisms in humid environments, such as the human oral cavity, resulting in infectious processes. Among oral diseases, dental caries presents as one of the most prevalent human diseases, especially in childhood. The carious process is characterized as a chronic and multifactorial disease which is related to the presence of Streptococcus mutans group, especially S. mutans. Acquisition of S. mutans, along with high intake of sugar, establishes a favorable environment for the development of caries. This microorganism is always present in the potentially cariogenic dental biofilm. In addition, there is strong evidence that glucan production is essential for expression of the Streptococcus mutans group virulence, contributing to the effective adherence of the bacterial to the dental surface, through exposure to sucrose. In addition to the recognized measures of prevention of dental caries, such as the mechanical procedures of cariogenic biofilm removal, the adequacy of diet, and the use of fluorine, new strategies are investigated. As alternative therapy are sought new antimicrobial agents of natural origin, especially of plants. In general, these phytotherapeutic antimicrobial agents exhibit diverse structures that reduce the potential for emergence of resistant microbial populations. The objective of this work was to evaluate the activity of extracts of Erythrina spp bark on population growth and biofilm formation of Streptococcus mutans group. A collection of bacteria from this taxonomic group, derived from biofilms positioned, was used distinctly on the palatal and vestibular surfaces of the oral cavity of pre-school age children. Biofilm production assays were conducted on glass and hydroxyapatite (HPA), in which three isolates with different levels of virulence were selected. In the inhibition assay with Erythrina spp. extracts, reference strains ATCC 25175 (S. mutans) and ATCC 27392 (S. sobrinus) were included, conducted on microplates. The efficiency of inhibition of the bacteria varied with the mode of extraction of the extract and with the virulence of the isolates. The results were promising for concentrations above 750μg.mL-1, with significant inhibitions of bacterial growth and disruption of the biofilms of HPA isolates.