Search

The effect of two subinhibitory antibiotic concentrations of ampicillin and vancomycin during growth on the adhesion of Enterococcus faecalis1131 to glass and silicone rubber was studied in a parallel plate flow chamber. Initial deposition rates and numbers of adhering bacteria after 4 h were higher on hydrophilic glass than on hydrophobic silicone rubber, regardless of growth conditions. The presence of 1/4 minimal inhibitory concentration (MIC) of ampicillin during growth reduced enterococcal adhesion to both substrata, but growth in the presence of 1/4 MIC vancomycin did not affect the adhesion of E. faecalis. Moreover, enterococcal adhesion increased after growth in the presence of 1/8 MIC vancomycin. The increased adhesion after growth in the presence of subinhibitory concentrations of vancomycin may have strong implications for patients living with implanted biomaterials, as they may suffer adverse effects from use of this antibiotic, especially since bacteria once adhered are less sensitive to antibiotics.

Surface electrical characterization of metals and semiconductors with extensive geometry continues to be of interest. This work explores the electrical information that can be extracted from the electrokinetic (zeta) potential of metallic surfaces, and proposes an analytical model based on streaming potential/current data. In particular, our study focuses on the alloy Ti6Al4V, which is capable of modifying its surface electrical properties after excitation with ultraviolet irradiation due to the semiconductor properties of its TiO2passivation layer. Evidence is presented for the first time of electronic activity inside the passivation layer following UV excitation. Charge displaced through sample (Q), electrons density (evol), surface charge density (σ) and current density (J) are extracted from the proposed model. The amount of displaced charge through Ti6Al4V disks not exposed to UV irradiation was similar to that displaced inside the thin TiO2excited layer. Relative conductivity of the TiO2excited layer versus Ti6Al4V showed a difference of up to five orders of magnitude between the two samples. The model is suitable for application to any metal and any excited semiconductor, thus increasing the usefulness of electrokinetic characterization based on streaming potential/current measurements.

The effect of two subinhibitory antibiotic concentrations of ampicillin and vancomycin during growth on the adhesion of Enterococcus faecalis 1131 to glass and silicone rubber was studied in a parallel plate flow chamber. Initial deposition rates and numbers of adhering bacteria after 4 h were higher on hydrophilic glass than on hydrophobic silicone rubber, regardless of growth conditions. The presence of 1/4 minimal inhibitory concentration (MIC) of ampicillin during growth reduced enterococcal adhesion to both substrata, but growth in the presence of 1/4 MIC vancomycin did not affect the adhesion of E. faecalis. Moreover, enterococcal adhesion increased after growth in the presence of 1/8 MIC vancomycin. The increased adhesion after growth in the presence of subinhibitory concentrations of vancomycin may have strong implications for patients living with implanted biomaterials, as they may suffer adverse effects from use of this antibiotic, especially since bacteria once adhered are less sensitive to antibiotics.