To prevent the high frequency of wound infections, anti-bacterial agents can be loaded onto composites. In the present study, the antibiotic tetracycline hydrochloride (TC)was incorporated, for the first time, in collagen type I membranes coated with nano-sized SiO2-CaOP2O5 bioactive glass (n-BG) obtained by a sol-gel chemical route. Collagen membranes coated with n-BG were immersed in simulated body fluid (SBF) containing 0.25, 0.75 or 1.25 mg mL−1 of TC for 48 h at 37∘C following a coprecipitation method. The antibiotic was released in distilledwater at 37∘C for up to 72 h. The antibacterial activity of the composites was evaluated in vitro by the inhibition zone test and plate count method. Two different Staphylococcus aureus strains, S. aureus ATCC29213 and S. aureus ATCC25923, were exposed to the biomaterials. The results showed that the incorporation but not the release of TC was dependent on the initial concentration of TC in SBF. The biomaterials inhibited S. aureus growth, although the efficacy was similar for all the concentrations. The results allow us to conclude that the new composite could have potential in the prevention of wound infections.
Plants of the Apiaceae family usually contain coumarins. These are used worldwide in traditional medicine, as well as in modern therapeutics. The aim of our study was to determine the antimicrobial activity of four extracts (methanolic and petroleum ether extracts) obtained from two Apiaceae species: Seseli devenyense (fruits) and Peucedanum luxurians (herb). The activity of the investigated extracts was tested against 7 strains of Gram+ bacteria, and 7 strains of Gram-, as well as three of yeast. The results of this show that the best activity of such extracts (specifically, by way of petroleum ether) was seen as being against Staphylococcus aureus strains.
Quaternary ammonium salts (QAS) belong to surfactant commonly used both, in the household and in different branches of industry, primarily in the process of cleaning and disinfection. They have several positive features inter alia effectively limiting the development of microorganisms on many surfaces. In the present work, two compounds were used as biocides: hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide) that belongs to the gemini surfactant (GS), and its single analogue - dodecyl(trimethyl)ammonium bromide (DTAB). Two fold dilution method was used to determine the minimum concentration of compounds (MIC) which inhibit the growth of bacteria: Staphylococcus aureus (ATCC 6538 and an environmental strain), Pseudomonas aeruginosa (ATCC 85327 and an environmental strain), and yeast Candida albicans (ATCC 11509 and an environmental strain). The viability of cells in liquid cultures with addition of these substances at ¼ MIC, ½ MIC and MIC concentrations were also determined. The obtained results show that DTAB inhibits the growth of bacteria at the concentration of 0.126-1.010 µM/ml, and gemini surfactant is active at 0.036-0.029 µM/ml. Therefore, GS is active at more than 17-70-fold lower concentrations than its monomeric analogue. Strains isolated from natural environment are less sensitive upon testing biocides than the references strains. Both compounds at the MIC value reduced the number of cells of all strains. The use of too low concentration of biocides can limit the growth of microorganisms, but often only for a short period of time in case of special environmental strains. Later on, they can adapt to adverse environmental conditions and begin to evolve defence mechanisms.
The increasing antibiotic resistance of pathogenic bacteria calls for the development of alternative antimicrobial strategies. Possible approaches include the development of novel, broad-spectrum antibiotics as well as specific targeting of individual bacterial virulence factors. It is impossible to decide currently which strategy will prove more successful in the future since they both promise different advantages, but also introduce diverse problems. Considering both approaches, our laboratory's research focuses on the evaluation of hemocidins, broad-spectrum antibacterial peptides derived from hemoglobin and myoglobin, and staphostatins, specific inhibitors of staphopains - Staphylococcus aureus secreted proteases that are virulence factors regarded as possible targets for therapy. The article summarizes recent advances in both fields of study and presents perspectives for further development and possible applications.
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