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Browsing by Author "Tavaria, F.K."

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  • Chitosan: antimicrobial action upon staphylococci after impregnation onto cotton fabric
    Publication . Tavaria, F.K.; Soares, J.C.; Reis, I.L.; Paulo, M.H.; Malcata, F.X.; Pintado, M.E.
    Background: High levels of viable Staphylococcus aureus, which are often found on inflamed skin surfaces, are usually associated with atopic dermatitis. Textiles, owing to their high specific surface area and intrinsic hydrophilicity, retain moisture while also providing excellent environmental conditions for microbial growth and proliferation. Recently, a number of chemicals have been added to textiles, so as to confer antimicrobial activity. Aims: To evaluate the antimicrobial action of chitosan upon selected skin staphylococci. Methods and Results: We isolated staphylococci from normal skin of 24 volunteers and studied their survival upon contact with chitosan-impregnated cotton fabric. Low and high molecular weight chitosans were used at two concentrations; all four did effectively reduce the growth of some staphylococci (namely Staph. aureus), by up to 5 log cycles, thus unfolding a potential towards control and even prevention of related skin disorders. Conclusion: Our data suggest an effective, but selective antibacterial action of chitosans towards skin bacteria. Significance and Impact of the Study: The possibility to use a natural biopolymer incorporated in a textile to alleviate and even treat some of the symptoms associated with this skin condition may raise an alternative to existing medical treatments. The selectivity observed prevents full elimination of bacteria from the skin surface, which is an advantage.
    2012Journal article Restricted access Show more
  • A comprehensive study into the impact of a chitosan mouthwash upon oral microorganism's biofilm formation in vitro
    Publication . Costa, E. M.; Silva, S.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F.K.; Pintado, M. E.
    Modern dentistry emphasizes the importance of dental plaque control to improve oral health. To that endthe development of oral care formulations has been geared toward the incorporation of antiplaque agentsthat may play a crucial role in oral health maintenance. In later years the research into antiplaque agentshas led to the discovery of compounds with significant capability to affect biofilm formation. Among thesecompounds was chitosan, a polysaccharide which showed great ability to interfere with Streptococcusmutans biofilm formation. As such the aim of this work was to incorporate chitosan into a mouthwashmatrix and assess its effect upon biofilm formation of oral microorganisms. This assessment was per-formed via study of the impact the mouthwash upon microbial adherence, biofilm formation and maturebiofilms. Additionally, the action of the chitosan mouthwash was compared with two commerciallyavailable mouthwashes. The results here obtained show that only the chitosan containing mouthwashwas capable of interfering with all microorganisms’ adherence, biofilm formation and mature biofilmswhile at the same time showing vastly superior activity than both commercial mouthwashes assayed.As such a chitosan mouthwash shows great potential as a natural and efficient alternative to traditionalmouthwashes.
    2014Journal article Restricted access Show more
  • Evaluation and insights into chitosan antimicrobial activity against anaerobic oral pathogens
    Publication . Costa, E.M.; Silva, S.; Pina, C.; Tavaria, F.K.; Pintado, M.M.
    The objective of this study was to assess the antimicrobial capability of non-chemically altered chitosan as an alternative to traditional antimicrobials used in the treatment of oral infections. The action mechanism of chitosan was also ascertained. High and low molecular weight chitosan showed antimicrobial activity at low concentrations for all tested bacteria with the MICs varying between 1 and 7 mg/ ml with a drop of efficacy relatively to the action of LMW chitosan. In addition chitosan showed also to be an effective bactericidal presenting bactericidal effect within 8 h at the latest. Additionally the evaluation of chitosan’s action mechanism showed that both MWs acted upon the bacterial cell wall and were not capable of interacting with the intracellular substances, as showed by the inefficacy obtained in the flocculation assay
    2012Journal article Restricted access Show more
  • Probiotic adhesion to skin keratinocytes and underlying mechanisms
    Publication . Lizardo, M.; Magalhães, R.M.; Tavaria, F.K.
    2021-11-23Conference object Open access Show more