BackgroundIncrease in vancomycin (Van)-resistant bacterial strains including vancomycin-resistant Staphylococcus aureus (VRSA) and lack of new effective antibiotics have become a formidable health problem.Materials and methodsWe designed a new conjugate composed of Van and a peptide Hecate (Hec; Van/Hec), and its potential antimicrobial activity was evaluated.ResultsResults from disk diffusion test, time-kill assay, determination of minimum inhibitory concentration (MIC), microscopy, and comet assay showed strong antimicrobial effects of Van/Hec against wild-type, methicillin-resistant Staphylococcus aureus (MRSA) and VRSA. Microscopy revealed that the exposure to Van/Hec results in disruption of bacterial cell integrity in all tested strains, which was not observed in case of Van or Hec alone.ConclusionOverall, we showed that the preparation of conjugates from antibiotics and biologically active peptides could help us to overcome the limitation of the use of antibiotic in the treatment of infections caused by multidrug-resistant bacteria.

Sparsely tested group of platinum nanoparticles (PtNPs) may have a comparable effect as complex platinum compounds. The aim of this study was to observe the effect of PtNPs in in vitro amplification of DNA fragment of phage λ, on the bacterial cultures (Staphylococcus aureus), human foreskin fibroblasts and erythrocytes. In vitro synthesized PtNPs were characterized by dynamic light scattering (PtNPs size range 4.8–11.7 nm), zeta potential measurements (-15 mV at pH 7.4), X-ray fluorescence, UV/vis spectrophotometry and atomic absorption spectrometry. The PtNPs inhibited the DNA replication and affected the secondary structure of DNA at higher concentrations, which was confirmed by polymerase chain reaction, DNA sequencing and DNA denaturation experiments. Further, cisplatin (CisPt), as traditional chemotherapy agent, was used in all parallel experiments. Moreover, the encapsulation of PtNPs in liposomes (LipoPtNPs) caused an approximately 2.4x higher of DNA damage in comparison with CisPt, LipoCisPt and PtNPs. The encapsulation of PtNPs in liposomes also increased their antibacterial, cytostatic and cytotoxic effect, which was determined by the method of growth curves on S. aureus and HFF cells. In addition, both the bare and encapsulated PtNPs caused lower oxidative stress (determined by GSH/GSSG ratio) in the human erythrocytes compared to the bare and encapsulated CisPt. CisPt was used in all parallel experiments as traditional chemotherapy agent.

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