Percorrer por autor "Teixeira-Santos, Rita"
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- Antibacterial action mechanisms of honey: physiological effects of avocado, chestnut, and polyfloral honey upon Staphylococcus aureus and Escherichia coliPublication . Combarros-Fuertes, Patricia; Estevinho, Leticia M.; Teixeira-Santos, Rita; Rodrigues, Acácio G.; Pina-Vaz, Cidália; Fresno, José María; Tornadijo, María EugeniaNumerous studies have explored the antibacterial properties of di erent types of honey from all around the world. However, the data available describing how honey acts against bacteria are few. The aim of this study was to apply a flow cytometry (FC) protocol to examine and characterize the primary e ects of three varieties of honey (avocado, chestnut and polyfloral) upon physiological status of Staphylococcus aureus and Escherichia coli cells to reveal their antibacterial action mechanisms. The e ects of honey samples on membrane potential, membrane integrity, and metabolic activity were assessed using di erent fluorochromes, in a 180 min time course assay. Time-kill experiments were also carried out under similar conditions. Exposure of S. aureus and E. coli to the distinct honey samples resulted in physiological changes related to membrane polarization and membrane integrity. Moreover, honey induced a remarkable metabolic disruption as primary physiological e ect upon S. aureus. The di erent honey samples induced quite similar e ects on both bacteria. However, the depth of bacteria response throughout the treatment varied depending on the concentration tested and among honey varieties, probably due to compositional di erences in the honey.
- Evaluation of physiological effects induced by manuka honey upon staphylococcus aureus and escherichia coliPublication . Combarros-Fuertes, Patricia; Estevinho, Leticia M.; Teixeira-Santos, Rita; Rodrigues, Acácio G.; Pina-Vaz, Cidália; Fresno, José María; Tornadijo, María EugeniaSeveral studies have explored the antimicrobial properties of manuka honey (MkH). However, the data available regarding antibacterial action mechanisms are scarcer. The aim of this study was to scrutinize and characterize primary e ects of manuka honey (MkH) upon the physiological status of Staphylococcus aureus and Escherichia coli (as Gram-positive and Gram-negative bacteria models, respectively), using flow cytometry (FC) to reveal its antibacterial action mechanisms. E ects of MkH on membrane potential, membrane integrity and metabolic activity were assessed using di erent fluorochromes in a 180 min time course assay. Time-kill experiments were carried out under the same conditions. Additionally, MkH e ect on e ux pumps was also studied in an E. coli strain with an over-expression of several e ux pumps. Exposure of bacteria to MkH resulted in physiological changes related to membrane potential and membrane integrity; these e ects displayed slight di erences among bacteria. MkH induced a remarkable metabolic disruption as primary physiological effect upon S. aureus and was able to block effux pump activity in a dose-dependent fashion in the E. coli strain.