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Relevance. In the 21st century, humanity is faced with a pandemic unprecedented in recent history, which brought with it huge losses. All the efforts of world science are aimed at ensuring that the new coronavirus infection becomes vaccine-controlled. The Ministry of Health of Russia included vaccination against COVID-19 in the national calendar of preventive vaccinations. The most vulnerable and significant in the epidemiological chain are representatives of socially active, intensively communicating professions, including medical workers.Aims. The aim of the study was to assess the degree of severity of the post-vaccination immune response in employees of a medical organization vaccinated with the Gam-COVID-Vac preparation, who had not been ill and did not have antibodies before vaccination.Materials & Methods. The post-vaccination immunity of 80 vaccinated employees was assessed 42–62 days after the start of vaccination and 6 months later; assessment of the safety of vaccination with the Gam-Kovid-Vak vector vaccine; selection of optimal screening tests for laboratory examination of persons before the planned vaccination. The results of the PCR test for the detection of SARS-CoV-2 RNA (at the post-vaccination stage four times with an interval of 7 days) and the determination of M and G immunoglobulins to SARS-CoV-2 by the ELISA method were analyzed, postvaccination complications and reactions were assessed at different stages, monitoring the state of health and assessing the dynamics of the post-vaccination immune response.Results. A study conducted after 6 weeks showed the high immunological efficacy of the Gam-Covid-Vac vaccine; 100% of those vaccinated with one or two components of the vaccine had class G antibodies to SARS-CoV-2. Vaccination did not cause severe reactions during the observation period; among the side effects, general complaints and local pains at the injection site prevailed, which were of a short-term nature and did not have a significant impact on the health status and habitual rhythm of life of the participants. The resistance of those vaccinated to a new coronavirus infection decreased over time and amounted to 97.1% three months after vaccination and 95.6% after 6 months. COVID-19 disease in vaccinated employees (7.4% of cases of the number of vaccinated) was of moderate severity, did not lead to the development of pneumonia and respiratory failure, and did not require hospitalization.Conclusions. The results obtained allow us to conclude that the effectiveness of vaccination against COVID-19 is quite high. Revaccination is well tolerated clinically and «amplifies» the immune response when exposed to SARS-CoV-2. Immunization of employees of medical organizations is necessary, because. this focus group is the most epidemiologically potentially dangerous in terms of the spread of infection.

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Background. Data from the national registers of arthroplasty showed that about 12% of hip and knee arthroplasty undergo revision within 10 years after the primary surgery. The leading cause of hip revisions is aseptic loosening of components, knee joint periprosthetic infection (PPI). Some of the infectious complications, including those related to mechanical causes, remain out of sight. The aim of the study was to identify the frequency of unexpected infections during revision knee and hip arthroplasty performed for aseptic complications of any etiology. Materials and Methods. 839 cases of revision arthroplasty of knee and hip joints were analyzed, including 485 aseptic revisions in 450 patients. Clinical, X-ray, laboratory (complete blood count and comprehensive metabolic panel, coagulation panel) methods, synovial fluid analysis and microbiological examination of punctures, including intraoperative ones, were used. The ICM and EBJIS (European Bone and Joint Infections Society) consensus recommendations were used as criteria for assessing the presence of infection. Results. The average age of patients at the time of the revision was 61.7 years. The hip joint prevailed (59.4%), knee joint 40.6%. The growth of microorganisms in the intraoperative biomaterial was detected in 2.08% of observations: in 10 out of 287 patients after aseptic revision of the hip joints and in none of the 198 revisions of the knee joints. In 8 out of 10 cases, the causative agents were coagulase-negative staphylococci, including 6 MRSE; in two cases, anaerobic bacteria. All revisions were carried out by a one-stage method. Patients with detected PPI underwent systemic antibacterial therapy. At the stage of catamnesis, reinfection was assumed in one of the 10 identified cases of PPI, the patient did not show up for revision. In control 63% of the group of the other (aseptic) 470 patients, PPI developed in 4 cases, two-stage revisions were carried out. Conclusions. The frequency of infections accidentally detected during aseptic revisions of large joints was 2.08%. Three-time examination of joint punctures, including intraoperative, provides additional opportunities for the diagnosis of PPI during aseptic revision, and also allows you to choose the optimal stage of revision treatment. The experience gained makes it possible in certain cases to perform one-stage revision in the treatment of PPI.

Periprosthetic infection (PPI) after arthroplasty of large joints is the third (among the main causes of unsatisfactory results of surgical treatment) a serious threat to the health of patients. The «gold standard» for the diagnosis of PPI is the bacteriological examination of samples of periprosthetic tissues and synovial fluid. In 10-30% of cases, it is impossible to isolate microorganisms, which is explained by the difficulty of cultivation and taking antibiotics before sampling. The purpose of study is to demonstrate the diagnostic value of PCR diagnostics for identifying the genetic material of an infectious pathogen of a culture-negative periprosthetic infection. Material of the study is a description of a clinical case of a culture-negative periprosthetic infection that caused a second two-stage revision of the hip joint prosthesis In the first episode of PPI that occurred 3 years after hip replacement, a microbiological examination of the puncture of the trochanteric zone of the operated joint revealed a massive increase in methicillin-resistant Staphylococcus epidermidis (MRSE). A two-stage revision joint replacement was performed. 5 years after the revision, the patient was hospitalized with clinical and radiological signs of PPI, while examining the puncture of the joint revealed characteristic PPI cytosis. Microbiological examination of punctate and intraoperative aspirate at the first stage of the repeated two-stage revision endoprosthesis replacement did not reveal aerobic and anaerobic microorganisms. In PCR studies, the DNA of methicillin-sensitive Staphylococcus aureus (MSSA) was detected in washouts from the removed components of the endoprosthesis; no resistance marker (mecA gene) was found. Given the concomitant oncological disease, this result determined the appointment of pathogenetic antibiotic therapy, the effectiveness of which was confirmed after 8 weeks at the II stage of revision. The PCR study of joint and trochanteric punctures (before surgery), flushing from the removed spacer components (after ultrasound treatment) and intraoperative aspirate from the joint did not reveal Staphylococcus aureus DNA and resistance marker (mecA gene). In some cases of periprosthetic infection, traumatologists and orthopedists deal with culturally negative results of a microbiological study of the patient’s biomaterial and swabs from the components of endoprostheses in the presence of clinical manifestations of PPI, confirmed by laboratory diagnostics and X-ray examination. According to the literature, such clinical situations are observed in 10-30% of cases and are caused by previous antibiotic therapy in the early stages of an infectious complication. After surgical treatment of PPI for the selection of adequate antibiotic therapy, such patients need to at least indirectly determine the type of infection pathogen, which is achieved by the use of additional diagnostic methods, such as a PRC study. In the case described by us, after a course of antibiotic therapy, prescribed according to the results of the first PCR study, the patient’s body does not contain DNA traces of the desired infectious agent. Thus, the repeated PCR not only confirmed the accuracy of the initial diagnosis of the source of infection, but also further illustrated the success of the rehabilitation of the periprosthetic infection using a correctly selected antibacterial drug at the previous stage of the study. The use of the PCR method made it possible to diagnose the pathogen and prescribe adequate antibiotic therapy for culture-negative periprosthetic infection.