Background. The number of surgeries on the musculoskeletal system is increasing every year. Along with the increasing access to orthopedic care, the number of patients with orthopedic infection, the etiological agents of which can be from various taxonomic groups, is also increasing. Staphylococcus aureus and different types of coagulase-negative staphylococci (CoNS), including S. epidermidis and S. lugdunensis, together are the causative agents in 70% of cases. Aim of the study — to analyze the dynamics of the microbial spectrum isolated from patients of the septic surgery department for the period from 2011 to 2022. Methods. We performed a retrospective analysis of the microbial spectrum isolated from patients who were treated in the septic surgery department from January 1, 2011 to December 31, 2022. The leading pathogens were microorganisms whose share in the spectrum exceeded 3.5%. Of the isolated pathogens, 48.8% were the only etiological agents, and microbial associations were detected in 51.2% of the isolated pathogens. Results. A total of 10,327 bacteria strains were identified over the 12-year period. The leading microorganisms causing orthopedic infection were Staphylococcus spp., Enterococcus spp., Propionibacterium spp., Pseudomonas aeruginosa, Corynebacterium spp., Streptococcus spp., Klebsiella spp. and Acinetobacter spp. In the dynamics of isolated pathogens during the analyzed period, several trends were determined: a decrease in the shares of S. aureus, Enterococcus spp., P. aeruginosa, Acinetobacter spp. and an increase in the shares of CoNS and Corynebacterium spp. Conclusion. During 12 years, in the microbial spectrum of orthopedic infection in patients of the septic surgery department of our Center, Gram-positive bacteria, in the majority representatives of the genus Staphylococcus, prevailed. At the same time, a significant decrease in the share of S. aureus strains and an increase in the frequency of isolation of various species of CoNS were registered. A significant decrease in the number of non-fermenting Gram-negative bacteria was also revealed.

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.

Background. Replacement of bone defects in the surgical treatment of chronic osteomyelitis is a key step to prevent recurrence of infection and potential fractures at the site of rehabilitation. Bone cement, biodegradable synthetic materials, as well as autologous, allogeneic, and xenogeneic bone tissue have become widespread in surgical practice. Giving these materials antibacterial properties will expand their use in the treatment of bone and joint infections, shorten the treatment time, and improve the patients’ quality of life. The aim of the study — to analyze the mid-term results of the second stage of surgical treatment for chronic osteomyelitis in long bones, depending on the type of used vancomycin-impregnated bone graft material: an original biodegradable mineralized material based on allogeneic bone or a commercially available biocomposite material consisting of β-tricalcium phosphate and hydroxyapatite. Methods. The study included 25 patients who underwent the second stage of surgical treatment for chronic osteomyelitis. After removal of the cement spacer, the defect was replaced in Group 1 (n = 14) with a biocomposite material ReproBone® Granules with the addition of vancomycin, while in Group 2 (n = 11) — with an original mineralized allograft impregnated with vancomycin. Laboratory tests, vancomycin concentration in the drainage fluid, and the presence of infection recurrence within 1-3 years after surgery were evaluated. Results. The groups did not differ in gender, age, and duration of the disease. The volume of the cavity defect was significantly higher in Group 2 (50 ml vs 14 ml; p = 0.0004). The vancomycin concentration in the drainage fluid from the first day after surgery in Group 2 was more than 10 times higher than in Group 1 (p = 0.0300) and remained at a high level until the 5th day. Osteomyelitis recurrence was observed in 14% of patients in Group 1 and was absent in Group 2. Conclusions. Standard approach to the treatment of chronic osteomyelitis using antimicrobial spacers does not ensure complete eradication of microbial pathogens that continue to persist in bone tissue. The original biodegradable mineralized bone graft material based on allogeneic bone creates significantly higher local vancomycin concentrations and demonstrates clinical efficacy in all applications.

The objective of this study was to develop a method for forming an antimicrobial wound coating based on chitosan and polyvinylpyrrolidone using 3D printing technology. The properties of the coating were then studied in vitro and in vivo to improve the treatment outcomes of deep burns. The resulting coating was a 4% hydrogel of medium molecular weight chitosan with the addition of 1% povidone iodine and dermal fibroblasts. After transplantation, the coating was covered with “Foliderm” film. The coating was formed using an extrusion 3D bioprinter, with printing parameters determined experimentally. The samples were first studied in vitro. Scanning electron microscopy was used to evaluate the coating’s microarchitecture and its interaction with dermal fibroblasts. A colorimetric test was conducted to assess cell metabolic activity and cytotoxicity, and antimicrobial activity against reference strains of Staphylococcus aureus was analyzed. An experiment was conducted to evaluate the in vivo properties of the coating. Nineteen male Wistar rats were used in the study. An injury was inflicted that resulted in a deep thermal contact burn, affecting all layers of skin and subcutaneous fatty tissue, with an area of approximately 20 cm2. The animals were divided into three groups: experimental (with the application of the developed coating), comparative (using the traditional and widespread method of treatment with Levomekol ointment) and control (without treatment). The study lasted for 38 days and found that the developed coating is highly biocompatible, atraumatic, elastic, and adheres well to wounds. Chitosan was used to create a porous structure with channels running parallel to each other. The coating cells are evenly distributed on the surface of the matrix, specifically on the walls of the pores. The inclusion of 1% povidone iodine in the polymer resulted in high antimicrobial activity without significantly affecting the activity of the cells in the composition. The experiment on applying a coating for treating deep thermal burns demonstrated that the developed coating had a positive effect on the wound healing process. This effect was characterized by a higher rate of epithelization and a significantly lower incidence of infectious complications compared to other experimental groups. In the histological study, the experimental group outperformed the control and comparison groups in the quality of the formed granulation tissue, the number of newly formed capillaries, and the severity of the local inflammatory process.

Background. Stenotrophomonas maltophilia (S. maltophilia) is a gram-negative non-fermenting bacillus and is a rare pathogen of orthopedic infection. Due to the relatively low virulence of S. maltophilia, many clinicians are still faced with the question of whether this bacterial species is simply a colonizing agent or the true cause of infection. Aim of the study to raise the awareness of practitioners about S. maltophilia as a rare pathogen of orthopedic infection. Methods. A retrospective analysis was performed concerning the frequency of S. maltophilia isolation from patients treated at the Vreden Center for periprosthetic infection and/or osteomyelitis from January 1, 2009 to October 31, 2022. The literature search by keywords was carried out in the PubMed/MEDLINE, Scopus, eLIBRARY, and Cyberleninka databases. The search retrieved 587 articles published in Russian or English over the period from 2012 to November 2022. Results. During the study period, 9 cases of orthopedic monoinfection with S. maltophilia were identified in 9 patients aged 36 to 83 years. At the time of admission, no leukocytosis was detected in patients, and only 2 of 9 patients had elevated C-reactive protein level. S. maltophilia is naturally resistant to many broad-spectrum antibiotics. Co-trimoxazole is considered the drug of choice for the treatment of S. maltophilia infection. The limited choice of drugs for targeted therapy, the presence of multiple determinants of antibiotic resistance, the existence of microbial associations and patient risks including implantation, chronic nature of infection, elderly age, as well as the presence of significant concomitant somatic pathology can lead to the ineffectiveness of the ongoing treatment of infections caused by S. maltophilia. Our experience shows that in the case of sensitivity of S. maltophilia strain to co-trimoxazole it is possible to prescribe this drug for a long course as monotherapy, provided that the radical surgical treatment of the focus is performed.