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- Evaluation of the activity of potential antimicrobials against lactic acid bacteria isolated from spoiled food sauces in media with or without added sucrosePublication . Costa, Eduardo; Silva, Sara; Matias, O.; Couto, José A.; Gomes, Ana M.; Pintado, M. M.
- Wild mushroom extracts as inhibitors of bacterial biofilm formationPublication . Alves, Maria José; Ferreira, Isabel C. F. R.; Lourenço, Inês; Costa, Eduardo; Martins, Anabela; Pintado, ManuelaMicroorganisms can colonize a wide variety of medical devices, putting patients in risk for local and systemic infectious complications, including local-site infections, catheter-related bloodstream infections, and endocarditis. These microorganisms are able to grow adhered to almost every surface, forming architecturally complex communities termed biofilms. The use of natural products has been extremely successful in the discovery of new medicine, and mushrooms could be a source of natural antimicrobials. The present study reports the capacity of wild mushroom extracts to inhibit in vitro biofilm formation by multi-resistant bacteria. Four Gram-negative bacteria biofilm producers (Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, and Acinetobacter baumannii) isolated from urine were used to verify the activity of Russula delica, Fistulina hepatica, Mycena rosea, Leucopaxilus giganteus, and Lepista nuda extracts. The results obtained showed that all tested mushroom extracts presented some extent of inhibition of biofilm production.Pseudomonas aeruginosa was the microorganism with the highest capacity of biofilm production, being also the most susceptible to the extracts inhibition capacity (equal or higher than 50%). Among the five tested extracts against E. coli, Leucopaxillus giganteus (47.8%) and Mycenas rosea (44.8%) presented the highest inhibition of biofilm formation. The extracts exhibiting the highest inhibitory effect upon P. mirabilis biofilm formation were Sarcodon imbricatus (45.4%) and Russula delica (53.1%). Acinetobacter baumannii was the microorganism with the lowest susceptibility to mushroom extracts inhibitory effect on biofilm production (highest inhibition—almost 29%, by Russula delica extract). This is a pioneer study since, as far as we know, there are no reports on the inhibition of biofilm production by the studied mushroom extracts and in particular against multi-resistant clinical isolates; nevertheless, other studies are required to elucidate the mechanism of action.
- Antimicrobial and antibiofilm activity of chitosan on the oral pathogen Candida albicansPublication . Costa, Eduardo; Silva, Sara; Tavaria, Freni; Pintado, ManuelaOral candidiasis is particularly evident, not only in cancer patients receiving chemotherapy, but also in elderly people with xerostomy. In general, Candida is an opportunistic pathogen, causing infections in immunocompromised people and, in some cases, when the natural microbiota is altered. Chitosan, a natural derivative of chitin, is a polysaccharide that has been proven to possess a broad spectrum of antimicrobial activity that encompasses action against fungi, yeast and bacteria. While recent studies have revealed a significant antibiofilm activity upon several microorganisms, including C. albicans, little is known regarding the impact of chitosan upon the adhesive process or mature biofilms. With that in mind, the purpose of this work was to evaluate, in vitro, the capability of chitosan to inhibit C. albicans growth and biofilm formation. The results obtained showed that chitosan is capable of inhibiting C. albicans planktonic growth (HMW, 1 mg/mL; LMW, 3 mg/mL). Regarding biofilm growth, chitosan inhibited C. albicans adhesion (ca. 95%), biofilm formation (percentages above 90%) and reduced mature biofilms by ca. 65% and dual species biofilms (C. albicans and S. mutans) by ca. 70%. These results display the potential of this molecule to be used as an effective anti-Candida agent capable of acting upon C. albicans infections.
- Potential prebiotic effect of fruit and vegetable byproducts flour using in vitro gastrointestinal digestionPublication . Andrade, Roberta Melquia des Silva de; Silva, Sara; Costa, Célia Maria; Veiga, Mariana; Costa, Eduardo; Ferreira, Mariana Simões Larraz; Gonçalves, Edira Castello Branco de Andrade; Pintado, Manuela EstevezFruit and vegetable byproducts (FVBP) present high content of bioactive compounds and dietary fibers and have demonstrated a positive modulatory effect upon gut microbiota composition. In the present study, the prebiotic potential of a FVBP flour obtained from solid byproducts after fruit and vegetable processing was evaluated after in vitro gastrointestinal digestion. An initial screening with three strains of Lactobacillus (Lactobacillus casei 01, Lactobacillus rhamnosus R11 and Lactobacillus acidophilus LA-5®) and one Bifidobacterium strain (Bifidobacterium animalis spp. lactis BB12®) was carried out and then the prebiotic effect of FVBP flour was performed with fecal samples of five donors. The changes in gut microbiota were evaluated at 0, 12, 24 and 48 h of fermentation by the real-time polymerase chain reaction (qPCR) method with 16S rRNA-based specific primers. The pH and short chain fatty acids (SCFA) production at each fermentation time were assessed. The fructooligosaccharides (FOS) were used as positive control. The impact of FVBP flour upon cell viability was also evaluated. FVBP flour showed higher prebiotic effect than FOS on growth enhancement of Lactobacillus after 48 h of fermentation and similar bifidogenic effect as FOS on Bifidobacterium growth at 12, 24 and 48 h of fermentation. SCFA production was observed when FVBP flour was used as carbon source, including butyrate, which supports the prebiotic potential of this flour. Additionally, it was observed that after in vitro gastrointestinal digestion, the FVBP flour at 3% promoted cell metabolism of Caco-2 cell line up to 67%. Thus, the present study demonstrates the viability of using a fruit and vegetable byproducts flour as a potential sustainable prebiotic source.