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Background.Local prevention of periprosthetic infection and treatment of infectious complications after various joints arthroplasties includes the use of polymethylmethacrylate-based spacers impregnated with antimicrobial agents. At the same time, the added components are able to change the bone cement characteristics and have variable antimicrobial effect duration. The aim of the studywas to evaluate the duration of antimicrobial activity and the effect on the MRSA ATCC 43300 biofilm formation on bone cement samples with gentamycin impregnated with vancomycin and/or highly dispersed silver.Materials and Methods.Samples were made from bone cement DePuy CMW 1 Gentamicin and mixed with vancomycin and/or highly dispersed silver. The elemental composition was studied by scanning electron microscopy and  micro-x-ray  spectral  analysis.  The  study  of  the  antimicrobial  activity  duration  was  performed  by  daily  applying an  incubation  solution  with  samples  to  the  bacterial  lawn  surface.  The  effect  on  biofilm  formation  was  evaluated  by immersing the test samples in LB-broth with MRSA.Results.The control samples did not have antimicrobial activity (AMA) against MRSA ATCC 43300. Test samples, additionally containing 10 wt.% of vancomycin was effective for 9 days. When adding highly dispersed silver, the lengthening of the samples activity time was recorded. So, when applying 2.5 wt.% of highly dispersed silver, the duration of AMA was 21 days, and when increased to 10 wt.% — 34 days. Energydispersion analysis of the sample surface with 10 wt.% of vancomycin and highly dispersed silver showed that the skeletal structure type contains matrix component based on barium sulfate with silver inclusions. During the study of the samples effect  on  a  typical  strain  biofilm  formation,  no  statistically  significant  differences  were  found  between  the  optical density of gentian violet extracts in the negative control and in the medium with MRSA.Conclusion. The vancomycin with highly dispersed silver combination prolonged the antimicrobial activity of the samples against MRSA ATCC 43300 and effectively prevented the formation of microbial biofilms on its surface. Despite the fact that the conditions of the conducted experiment in vitro are not identical to the conditions of bone cement antimicrobial spacers clinical use, our results indicate the need to use spacers with a known duration of antimicrobial activity and to comply with the terms of temporary structures replacement.

Prevention of bacterial adhesion is one of the most important antivirulence strategies for meeting the global challenge posed by antimicrobial resistance. We aimed to investigate the influence of a peptidic S. aureus sortase A inhibitor on bacterial adhesion to eukaryotic cells and biofilm formation as a potential method for reducing S. aureus virulence. The pentapeptide LPRDA was synthesized and characterized as a pure individual organic compound. Incubation of MSSA and MRSA strains with LPRDA induced a subsequent reduction in staphylococcal adhesion to Vero cells and biofilm formation, as visualized by microscopic and spectrophotometric methods, respectively. LPRDA did not have a cytotoxic effect on eukaryotic or bacterial cells. The pentapeptide LPRDA deserves further investigation using in vitro and in vivo models of Gram-positive bacteriemia as a potential antibacterial agent with an antiadhesive mechanism of action.

Objective. To evaluate the resistance rate and production of carbapenemases in Klebsiella pneumoniae with phenotypic resistance to carbapenems isolated from patients with orthopedic infection. Materials and Methods. The materials for the study were tissue samples, aspirates and removed orthopedic devices of patients with orthopedic infection at the Vreden Russian Research Institute of Traumatology and Orthopedics, between 2017 and 2019. K. pneumoniae strains were identified in Microlatest by iEMS ReaderMF. These strains were tested for susceptibility to 15 antimicrobial agents by disk diffusion methods, as described by the EUCAST. The carbapenemase genes were investigated by RT-PCR. Results. Of 858 isolated cultures, 6.8% were resistant to carbapenems. Molecular genetic analysis showed that 43.1% of the cultures had blaNDM gene and 24.1% blaOXA-48. All isolates of K. pneumoniae were characterized by resistance to cefotaxime, moxifloxacin and ciprofloxacin. OXA-48-strains were MDR in 50.0% of cases, XDR in 42.9%, PDR in 7.1%. Strains with NDM-carbapenemases were XDR in 68.0% and PDR in 32.0% of cases. The most effective antibiotic was fosfomycin. Thus, 66.7% of NDM-isolates demonstrated sensitivity to fosfomycin. One isolate was PDR with both NDM and OXA-48. Conclusions. Over the period of three years, carbapenemase-producing K. pneumoniae were isolated in the orthopedic hospital. These isolates were not only resistant to carbapenems, but also to a number of other antimicrobial agents. Isolates differed in resistance phenotypes depending on the presence of carbapenemases group, while strains with gene blaNDM were more resistant than those with blaOXA-48.