Efeito antibiofilme e citotoxicidade do hidróxido de cálcio associado ao óleo essencial de Melaleuca alternifolia / Antibiofilm effect and cytotoxicity of calcium hydroxide associated with the Melaleuca alternifolia essential oil

Objetivo: Avaliar e comparar os efeitos antimicrobiano e antibiofilme, e a citotoxicidade promovida pela associação do hidróxido de cálcio ao óleo essencial de Melaleuca alternifolia (MA), em diferentes concentrações, e ao propilenoglicol (PG). Métodos: As seguintes medicações compuseram os grupos experimentais: G1) HC/MA 1%; G2) HC/MA 5%; G3) HC/MA 10%; G4) HC/MA 20%; e G5) HC/PG. Solução salina 0,85% e meio DMEM serviram como controle nos testes antimicrobianos e de citotoxidade em fibroblastos do ligamento periodontal humano (FbLP), respectivamente. A atividade antimicrobiana (n = 12) foi avaliada por meio do teste de difusão em ágar. O efeito antibiofilme (n = 12) imediato das medicações foi avaliado por meio do teste de viabilidade bacteriana em biofilmes de 72 horas de E. faecalis, formados sobre discos de dentina e tratados por sete dias com as medicações. Após a coleta microbiológica do biofilme remanescente, os discos de dentina foram imersos em meio estéril e armazenados por mais sete dias, para a análise do efeito antibiofilme residual das medicações, quando nova coleta microbiológica foi realizada. A atividade metabólica de FbLP foi avaliada por meio do ensaio colorimétrico MTS (n = 9). Os valores médios dos halos de inibição, em mm, das unidades formadoras de colônia, e o percentual de atividade metabólica celular foram analisados pelos testes Kruskal-Wallis e post hoc Dunn (α = 5%). Resultados:Todas as medicações experimentais apresentaram superior ação antimicrobiana e antibiofilme comparadas ao controle, solução salina (p < 0,05), e mantiveram viáveis os FbLP, semelhante ao controle DMEM (p > 0,05). Conclusão: A associação do óleo essencial de Melaleuca alternifolia, nas concentrações de 1%, 5%, 10% e 20%, ao hidróxido de cálcio promoveu excelente ação antimicrobiana, antibiofilme e biocompatibilidade com fibroblastos, de forma semelhante à associação com propilenoglicol.

Aim:To evaluate and compare the antimicrobial and antibiofilm effect, as well as the cytotoxicity of calcium hydroxide (CH) associated with the Melaleuca alternifolia (MA)essential oil, in different concentrations, and with propylene glycol. Methods: The following medications composed the experimental groups: G1) CH/MA 1%; G2) CH/MA 5%; G3) CH/MA 10%; G4) CH/MA 20%; and G5) CH/PG. Saline solution and culture medium DMEM were used as a control in antimicrobial and cytotoxicity tests in human periodontal ligament fibroblasts (PDLF), respectively. The antimicrobial activity (n = 12) was evaluated by the disk-diffusion agar method. The immediate antibiofilm effect (n = 12) of the medications was evaluated for bacterial viability in 72 hours-biofilms of E. faecalis, formed on the dentin disc surface and treated for seven days with medications. After microbiological sampling of the remaining biofilm, the dentin discs were immersed in sterile culture medium and stored for another seven days, for analysis of the residual antibiofilm effect of the medications, when a new microbiological sampling was performed. PDLF viability was evaluated by MTS colorimetric assay (n = 9). The mean values of the inhibition halos, in mm, the colony forming units, and the metabolic cell activity percentage were analyzed by means of Kruskal-Wallis and post hoc Dunn (α = 5%) tests. Results:All of the experimental medications presented higher antimicrobial and antibiofilm effects, when compared to the saline solution control (p < 0.05), and maintained the PDLF feasible, similar to the DMEM control (p > 0.05). Conclusions:The association of the Melaleuca alternifolia essential oil, at concentrations of 1%, 5%, 10%, and 20%, with calcium hydroxide promoted an excellent antimicrobial and antibiofilm activity, and biocompatibility with fibroblasts, similarly to the association with propylene glycol.

Food safety in raw milk production: risk factors associated to bacterial DNA contamination.

While human illness from milkborne pathogens may be linked to contamination of the product after pasteurization or improper pasteurization, such diseases are usually associated with consumption of raw milk or its by-products. Molecular biology tools were applied to investigate contamination by Listeria monocytogenes, Salmonella spp., some pathogenic strains of Escherichia coli, and Campylobacter jejuni in 548 raw milk samples from 125 dairy farms established in two regions from southern Brazil. Moreover, 15 variables were evaluated for their association with raw milk contamination levels, and the risk factors were determined by multiple regression analysis. Salmonella spp. were more frequently detected, followed by pathogenic E. coli. There was difference in contamination index between the regions, in which risk factors such as temporary cattle confinement, low milk production, low milking machine cleaning frequency, and milk storage area without tile walls were identified. The risk factors were specific to each region studied. Nevertheless, the data can be used to improve milk quality of dairy farms/herds with similar management practices.