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BACKGROUND Orthopedic implant-related infection remains one of the most serious complications after orthopedic surgery. In recent years, there has been an increased scientific interest to improve prevention and treatment strategies. However, many of these strategies have focused on chemical measures. AIM To analyze the effect of alternating current electrical fields on bacterial adherence to titanium surfaces. METHODS Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were exposed to 6.5 V electrical currents at different frequencies: 0.5 Hz, 0.1 Hz, and 0.05 Hz. After exposure, a bacterial count was then performed and compared to the control model. Other variables registered included the presence of electrocoagulation of the medium, electrode oxidation and/or corrosion, and changes in pH of the medium. RESULTS The most effective electrical model for reducing S. aureus adhesion was 6.5 V alternating current at 0.05 Hz achieving a 90% adhesion reduction rate. For E. coli, the 0.05 Hz frequency model also showed the most effective results with a 53% adhesion reduction rate, although these were significantly lower than S. aureus. Notable adhesion reduction rates were observed for S. aureus and E.coli in the studied conditions. However, the presence of electrode oxidation makes us presume these conditions are not optimal for in vivo use. CONCLUSION Although our findings suggest electrical currents may be useful in preventing bacterial adhesion to metal surfaces, further research using other electrical conditions must be examined to consider their use for in vivo trials.

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.

108 isolates of Staphylococcus aureus, belonging to six large ribogroups according to the automated Ribo-Printer® system, were studied with two highly used molecular methods for epidemiological studies, namely multi-locus sequence typing (MLST) and spa typing, followed by BURP and eBURST v3 analysis for clustering spa types and sequence (ST) types. The aim was to evaluate whether automated ribotyping could be considered a useful screening tool for identifying S. aureus genetic lineages with respect to spa typing and MLST. Clarifying the relationship of riboprinting with these typing methods and establishing whether ribogroups fit single clonal complexes were two main objectives. Further information on the genetic profile of the isolates was obtained from agr typing and the search for the mecA, tst genes, and the IS256 insertion sequence. Automated ribotyping has been shown to predict spa clonal complexes and MLST clonal complexes. The high cost and lower discriminatory power of automated ribotyping compared to spa and MSLT typing could be an obstacle to fine genotyping analyzes, especially when high discriminatory power is required. On the other hand, numerous advantages such as automation, ease and speed of execution, stability, typeability and reproducibility make ribotyping a reliable method to be juxtaposed to gold standard methods.

The increase of multidrug-resistant bacteria remains a global concern. Among the proposed strategies, the use of nanoparticles (NPs) alone or associated with orthopedic implants represents a promising solution. NPs are well-known for their antimicrobial effects, induced by their size, shape, charge, concentration and reactive oxygen species (ROS) generation. However, this non-specific cytotoxic potential is a powerful weapon effective against almost all microorganisms, but also against eukaryotic cells, raising concerns related to their safe use. Among the analyzed transition metals, silver is the most investigated element due to its antimicrobial properties per se or as NPs; however, its toxicity raises questions about its biosafety. Even though it has milder antimicrobial and cytotoxic activity, TiO2 needs to be exposed to UV light to be activated, thus limiting its use conjugated to orthopedic devices. By contrast, gold has a good balance between antimicrobial activity as an NP and cytocompatibility because of its inability to generate ROS. Nevertheless, although the toxicity and persistence of NPs within filter organs are not well verified, nowadays, several basic research on NP development and potential uses as antimicrobial weapons is reported, overemphasizing NPs potentialities, but without any existing potential of translation in clinics. This analysis cautions readers with respect to regulation in advancing the development and use of NPs. Hopefully, future works in vivo and clinical trials will support and regulate the use of nano-coatings to guarantee safer use of this promising approach against antibiotic-resistant microorganisms.

The purpose of this work was to compare pre-made antibiotic-loaded spacers with two commercially available antibiotic agents and custom-made cements with three antibiotic agents added. We evaluated: (a) the validity of our procedures, (b) the control of the rate of infection in the long term, (c) complications, and (d) quality of life and patient satisfaction.A retrospective cohort study was performed on 112 consecutively treated patients between January 2010 and December 2013; 56 patients were treated with a pre-formed cement spacer (clindamycin + gentamicin), and 56 patients were treated with a spacer loaded with three antibiotic agents (clindamycin + gentamicin + vancomycin). Demographic data were collected: Classification of infection according to criteria of Cierny-Mader; microbiologic results; number of previous operations; and years of disease. Infection control or relapse after at least 18 months of follow-up was evaluated. Complications were recorded. Every patient completed the SF-36 test and Oxford Knee Score.With a follow-up of 32.87 months (standard deviation 12.04), at the end of treatment, amputation occurred in three of 112 patients because of recurrence of infection, and one patient died from other causes not related to the infection. The study population presented a rate of recurrence of infection of 2.70%.Our results suggest that a two stage re-implant with three antibiotic agents added to the spacer should be considered to avoid rescue procedures, especially in patients with multi-resistant micro-organism infections.

We studied the in vitro effects of gentamicin and vancomycin alone and in combination added to polymethylmethacrylate (PMMA) cement specimens on the bacterial adhesion of multiresistant clinical isolates. The PMMA specimens (discs) loaded with gentamicin (1.9%) or vancomycin (1.9%) or with a combination of the two were placed in Mueller-Hinton Broth inoculated with bacterial strains. After incubation, bacterial growth was determined by optical density (OD(540)) and sub-cultures. The biofilm PMMA-associated dye (crystal violet) was measured. Antibiotic concentrations in broth were determined by fluorescence polarisation immunoassay. All antibiotic-loaded PMMA cement specimens released high, inhibitory concentrations of gentamicin and vancomycin. However, differences in strain growth and adhesion were recorded. The clinical isolates Met-R/Gent-R CoNS showed no adhesion to gentamicin-loaded specimens for 24 h; strains with Gent-Intermediate susceptibility exhibited growth after 48 h but reduced adhesion. Some Gent-R strains exhibited growth and adhesion to antibiotic-loaded specimens similar to controls (plain discs). Only the VRSA strain (Staphylococcus aureus 5/7) and Escherichia coli were able to grow and adhere to vancomycin-loaded specimens after 24 h of incubation. The specimens loaded with the gentamicin + vancomycin combination showed a synergistic inhibitory effect against all tested strains (no bacterial growth). The degree of bacterial adhesion to PMMA cement loaded with gentamicin or vancomycin may be reduced in spite of a normal growth rate and is different for the tested strains. The effect of gentamicin and vancomycin on bacterial growth and adhesion to PMMA bone cement depends on the antibiotic concentrations, on the characteristics of each specific strain and on its ability to produce biofilm and adhere to antibiotic-loaded PMMA bone cement.

Objective — To describe the vascular distribution pattern of contrast medium during intraosseous regional perfusion (IORP) of the distal portion of the forelimb in horses. Sample Population — 13 cadaver forelimbs from 12 horses without vascular or orthopedic disease of the distal forelimb. Procedure — Serial lateromedial radiographs were taken of 10 heparinized cadaver distal forelimbs at 0, 1, 2, 6, 15, and 30 minutes during IORP of the third metacarpal bone (MCIII) using iodinated contrast medium and a tourniquet placed over the proximal MCIII. Vascular regions of interest (ROI) were created for each radiograph. Reviewers identified presence or absence of contrast in each ROI. This information was summarized to identify vessel-filling patterns over time. Vessel identification was verified using computed tomography angiography and latex perfusion studies on separate cadaver distal forelimbs. Results — During IORP, contrast medium filled the medullary cavity of the MCIII, exited via trans-cortical vessels and diffused distally to the remaining arteries and veins of the limb, distal to the tourniquet. Maximum vessel and soft tissue opacification occurred in most specimens at 6 and 30 minutes, respectively. Serial radiography vessel patterns matched those of CT images and dissected specimens. Conclusions and Clinical Relevance — Intraosseous regional perfusion provides a repeatable pattern of vascular distribution in the distal portion of the equine forelimb. This is the first documentation of arterial perfusion using this technique. Previous reports indicate that IORP only delivers medications to the venous vessels of the perfused limb. Maximum soft tissue perfusion was observed at 30 minutes. Master of Science