Relevance. Healthcare workers were among the most vulnerable groups during the COVID‑19 pandemic. High morbidity, considerable mortality, and frequent long-term consequences of the disease – including post-COVID syndrome, respiratory and psychoemotional disorders – necessitate a comprehensive assessment of occupational risks and medical outcomes in this population. An objective evaluation of the scale and factors influencing the health of healthcare workers during the pandemic is essential for the development of a sustainable system of prevention, occupational safety, and strategic planning in the healthcare sector, especially under recurring epidemic threats.

Materials and Methods. The study was conducted within the largest departmental healthcare network in Russia – JSC «Russian Railways» (covering 75 regions, approximately 60,000 employees). A total of 16,344 confirmed cases of COVID‑19 among medical personnel were analyzed for the period 2020–2022. Morbidity and mortality rates were assessed across professional, gender, and age groups. Additionally, 7,805 expert assessments of occupational causation were evaluated, including 2,583 postmortem examinations. Standard epidemiological methods were used: incidence rate calculations, intergroup comparisons, statistical analysis, and significance testing across different periods of the pandemic.

Results. The average COVID‑19 morbidity among healthcare workers was 93.2±1.5 per 1,000 employees, significantly higher than in all other personnel at Russian Railways (65.3±0.9 per 1,000; 1.43 times higher, p<0.0001), and higher than the national average (73.4±1.1 per 1,000; 1.27 times higher, > 0.0001), and higher than the national average (73.4±1.1 per 1,000; 1.27 times higher, p<0.0001) ). The highest risk of infection was among physicians – 381.4±15.2 per 1,000, which was 1.96 times higher than that of non-medical personnel (194.1±8.5 per 1,000; p 0.0001). Among nursing staff, the morbidity rate was 298.2±12.7, and among junior personnel – 221.3±9.8, both significantly higher than among non-medical staff (1.54 times, p <0.0001 and 1.14 times, p <0.01, respectively). The case fatality rate among healthcare workers was 0.70%±0.13%, which was 2.8 times higher than among the rest of the organization’s staff (0.25%; p <0.0001) . In the 7,805 expert assessments conducted, a direct occupational link to COVID‑19 was confirmed in 63.8% of postmortem and 67.8% of non-postmortem cases. The vast majority of those infected were women (89%), with an average age of 53.1±2.3 years. The age group 40–60 years accounted for 59% of all cases.

Conclusions. COVID‑19 had a significant occupational impact on healthcare workers. The results underscore the urgent need for comprehensive protective measures, including the provision of personal protective equipment, vaccination, regular health monitoring, post-COVID rehabilitation, psychological support, and formal legal recognition of COVID‑19 as an occupational disease when risk factors are confirmed.

The work is devoted to the development of a computer method for assessing the severity of pneumonia, which is a complication of COVID‑19, based on sets of clinical and laboratory indicators using machine learning (ML) methods. The work consisted of investigating the possibility of predicting using ML the computed tomography (CT) grade of severity of pneumonia. Groups of 31 patients with moderate or severe pneumonia (CT2–CT4) and 113 patients without pneumonia or with mild pneumonia (CT0–CT1) were compared. The database included 105 clinical and laboratory parameters. To compare groups, standard nonparametric χ² tests and the Mann-Whitney test (U-test) with Bonferroni-Holm correction for multiple testing were used. Along with traditional statistical methods, an original method of data mining was also used, allowing statistically sound identification of informative intervals of indicator values. To predict severity gradations, a set of ML methods was used, which included, along with widely known methods, also an original development. The research used the Data Master Azforus software package. The study confirmed the possibility of predicting the results of CT based severity grades by clinical and laboratory indicators using machine learning methods. The forecast efficiency according to ROC AUC was about 0.9. The introduction of the model into practice will help improve the accuracy and efficiency of diagnosing severe pneumonia.

Introduction. Antibiotic resistance in gram-negative bacteria causing urinary tract infections (UTIs) poses a serious threat to healthcare and requires regular monitoring of local resistance trends. Objective. To assess the dynamics of antibiotic resistance of dominant gram-negative flora of the urogenital tract in the adult population of the Central Federal District and Moscow in 2017–2022.

Materials and methods. A retrospective analysis of 34,532 urine samples from patients over 18 years of age with bacteriuria ≥105 CFU/ml was conducted. Microorganism identification was performed using MALDI-TOF MS, and sensitivity testing was performed using the disk diffusion method according to EUCAST standards. The dynamics of resistance to amikacin, gentamicin, tobramycin, ampicillin, levofloxacin, ciprofloxacin, cefepime, ceftazidime, and meropenem were studied. Results. In the period from 2017 to 2022, there was a statistically significant increase in the proportion of Escherichia coli and Klebsiella pneumoniae isolates resistant to cephalosporins, fluoroquinolones, and carbapenems. The detection rate of cephalosporin-resistant Proteus mirabilis isolates increased 3-fold in 2022 compared to 2017 (p<0.0001). The increasing resistance of urinary tract infections to cephalosporins, fluoroquinolones, and carbapenems poses a critical threat to empirical therapy. Conclusion. The growing resistance of dominant uropathogens to cephalosporins, fluoroquinolones, and carbapenems poses a critical threat to empirical UTI therapy and requires increased monitoring of the rational use of antimicrobials and increased epidemiological control.><0.0001) ). The increasing resistance of urinary tract infections to cephalosporins, fluoroquinolones, and carbapenems poses a critical threat to empirical therapy.

Conclusion. The growing resistance of dominant uropathogens to cephalosporins, fluoroquinolones, and carbapenems poses a critical threat to empirical UTI therapy and requires increased monitoring of the rational use of antimicrobials and increased epidemiological control.

Introduction. Chronic suppurative otitis media (CSOM) is a prevalent middle ear disease characterized by persistent tympanic membrane perforation, recurrent otorrhea, and hearing loss. Its pathogenesis involves chronic purulent inflammation caused by opportunistic microflora forming biofilms and exhibiting antibiotic resistance. The emergence of multidrug-resistant strains highlights the need to revise treatment strategies, emphasizing personalized therapy and advanced microbiological diagnostics.

The aim of this study is to study the etiological structure of CSOM pathogens and determine the sensitivity of the main microorganisms to antimicrobial drugs.

Materials and methods. In 2022–2024, 552 patients with CSOM were examined at the Federal State Budgetary Institution “The National Medical Research Center of Otorhinolaryngology of the Federal Medico-Biological Agency of Russia. A microbiological analysis of 586 samples of the middle ear was performed. The sensitivity of microorganisms to antimicrobial drugs was determined by the disco-diffusion method.

Results. A total of 81 microbial species were identified, including Staphylococcus aureus (23.8 %), Pseudomonas aeruginosa (10.6 %), Corynebacterium amycolatum (9.7%), and Candida spp. (9.7%). Microbial associations were registered in 40% of cases. A statistically significant increase in S. aureus detection was observed over three years (p=0.004), along with growing resistance to erythromycin (25.7%) and cefoxitin (11.2%). P. aeruginosa showed notable resistance to ciprofloxacin (38.8%) and piperacillin-tazobactam (24.4%).

Conclusion. CSOM is characterized by a wide range of bacterial and fungal pathogens and high antimicrobial resistance, underscoring the importance of microbiological monitoring and a personalized approach to patient treatment.

Objective. Characterize the clinical and epidemiological features of mumps infection in 2023–2024 in the Republic of Dagestan.

Materials and methods. Epidemiological and molecular biological methods were used in the work. A molecular biological study was conducted on the oropharyngeal swab samples taken from patients treated at the State Budgetary Institution of the Republic of Dagestan «Republican Center for Infectious Diseases, Prevention and Control of AIDS named after S.M. Magomedov», Makhachkala. Samples of biomaterial were taken upon admission, during treatment and before discharge. RNA of the mumps virus was detected in smears from the oropharyngeal swab samples using the polymerase chain reaction method. The material for the epidemiological study was the medical records of patients.

Results. The clinical and epidemiological features of mumps infection in 2023–2024 were considered using the Republic of Dagestan as an example. An analysis of laboratory-confirmed cases of mumps in hospitalized children and adults was carried out. Preservation of winter-spring seasonality was shown. Adolescents and young adults predominated in the age structure. In 53.66% of hospitalized patients, mumps was accompanied by the following complications: orchitis, pancreatitis, measles, meningitis. All patients were found to have had contact with patients with mumps. Unvaccinated children predominated among hospitalized children (76%). It was also shown that in the first three days from the onset of the disease, the RNA of the mumps virus is contained in oropharyngeal swabs at a concentration of 103–109 GE / ml. In unvaccinated individuals, viral RNA is detected much longer, which also emphasizes the importance of immunization.

Conclusion. Considering the clinical and epidemiological features of mumps infection at the present stage, the possibility of early detection of RNA of the mumps virus by PCR is shown, which will improve the diagnosis of this disease.

In recent decades, there has been a global trend towards an increase in the incidence of listeriosis. Within the framework of this study, a comprehensive
assessment of the epidemiological situation and features of the spread of listeriosis in the city of Moscow was carried out. Data from official statistical
reports were used for the analysis, as well as methods of retrospective epidemiological analysis using standard statistical tools and methods. The results
of the study showed that between 2014 and March 2025, 330 cases of listeriosis were registered in Moscow, of which 80 cases were recorded in 2024.
The incidence rate ranged from 0.1 cases per 100,000 population in 2015 to 0.74 cases per 100,000 population in 2024. Analysis of the age structure
of patients for the period from 2021 to 2024 revealed that 38% of cases are people aged 60–74 years, and 23% are patients aged 75–90 years. The
epidemiological peak in 2022 was observed among the 45–59-year-old age group, while in 2021 the largest number of cases was registered among
people aged 18–44 years. The increase in the number of confirmed cases of listeriosis is due to several factors, including improved diagnostic methods,
an increase in the number of immunosuppressive patients, food contamination with the pathogen, and the formation of antibiotic resistance. To
reduce the incidence of listeriosis, it is necessary to strengthen epidemiological surveillance, introduce modern molecular biological diagnostic
methods, optimize preventive measures and improve the regulatory framework governing epidemiological control and sanitary standards.

The proportion of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup W (NmW) has increase in recent years. NmW contribute the largest mortality ratio (up to 29%) compared to other serogroups. IMD caused by NmW with the sequence type ST‑11 has been associated with multiple causes of epidemiological problems abroad, are of particular epidemiological concern.

The aim of the study was to describe a fatal case of IMD caused by NmW with an analysis of the antigenic and genetic pathogen’s features.

Materials and methods. The description of clinical manifestations was taken from the GMI registration report form received by the Reference Center for Monitoring Bacterial Meningitis. The microbiological and molecular biological methods for the pathogen investigation were performed by generally accepted once using the plugins and information of the PubMLST database.

Results and discussion. The clinical manifestations of IMD fatal case with a diagnosis of «acute gastroenterocolitis, grade II hypovolemic shock» was described. The IMD was caused by NmW extracted from the cerebrospinal fluid. Pathogen typing detects the previously undescribed sequence type ST‑18929 from the ST‑11 complex (cc11), and the antigenic profile characteristic of this clonal complex, W: P1.5,2: F1–1. Whole genome analysis of the pathogen demonstrated minor differences from the cc11 clonal complex strains circulating in Moscow in 2013–2020.

Conclusion. The described case is a striking example of the atypical clinics of IMD caused by the NmW. The most genetically similar IMD pathogens of W serogroup have been repeatedly isolated in Moscow in previous years, which does not allow us to speak with confidence about the import of increased virulence pathogens into Russia.

In most cases, enterovirus infection (EVI) is characterized by an uncomplicated course and occurs in the form of herpangina, hand-foot-mouth syndrome, viral exanthema and enteritis. The most rare and complicated forms of EVI in children are associated with damage to the central nervous system. Every tenth case of encephalitis in a child ends in severe disability or death, and therefore encephalitis is a significant burden for public health, which determines the relevance of our work.

Objective: to demonstrate a clinical case of enterovirus encephalitis in a child. The clinical case we demonstrated reflects the polymorphism of the clinical manifestations of EVI: the onset of the disease in a child was accompanied by the appearance of febrile fever and symptoms of enteritis, followed by the development of encephalitis. The diagnostic search confirmed the etiology of enterovirus encephalitis with a positive analysis of cerebrospinal fluid by PCR, while it was not possible to isolate the virus from other loci, according to multispiral computed tomography of the brain, no pathological changes were noted. Thus, the clinical case we demonstrated made it possible to draw the attention of doctors to a rare form of enterovirus encephalitis with the realization of long-term neurological disorders in a child, which requires the development of specific methods of prevention and improvement of rehabilitation methods, allowing to reduce the risk of disability.

Introduction. Historically, men who have sex with men (MSM) are a stigmatized community in Russia, and this fact has negatively affects HIV prevention in this vulnerable group and complicates the study of HIV‑1 genetic variants.

The aim of our study was to characterize HIV‑1 variants in samples obtained in 2004–2025 from MSM living in Russia.

Materials and methods. Nucleotide sequences of the HIV‑1 pol gene fragment (2253–3369 bp) from the RuHIV and GenBank databases from 562 HIV-infected MSM living in the Russian Federation were analyzed. Genotyping, phylogenetic and cluster analysis were performed and p-distance calculation among the most common HIV‑1 genetic variants was carried out.

Results. Sub-subtype A6 comprised 44.84% of samples, subtype B – 35.94% of samples, and the proportion of HIV‑1 sub-subtype A6 statistically significantly increased in the period 2004–2025. An increase of the p-distance was found among sub-subtype A6 (from 0.044 to 0.054) and subtype B (from 0.05 to 0.072) viruses in 2004–2025. We obtained the evidence of both the blurring of the boundaries of the vulnerable MSM group and the ongoing circulation of subtype B among MSM in Russia. The influence of migration on the increase in the number of cases of rare and recombinant forms of HIV‑1 infections among MSM in Russia in recent years was shown.

Conclusion. The importance of studying the vulnerable MSM group for epidemiological surveillance of HIV infection in Russia is shown. The contribution of migration to the genetic diversity of HIV‑1 variants circulating in the country was revealed.

The article presents data on the incidence of infectious complications, their etiology, risk factors and prevention in patients with chronic renal failure receiving hemodialysis. The most frequent complication is catheter-associated bloodstream infections. Their incidence varies considerably from country to country. Calculating the frequency of infections using different denominators is a challenge in comparing data. Gram-positive microorganisms are the most frequent pathogens. Central venous catheters have a higher risk of infectious complications than other types of vascular access. Prophylaxis measures include recommendations for prevention of catheter-associated bloodstream infections, and the effectiveness of methicillin-resistant Staphylococcus aureus carrier sanitation, antimicrobial agents around the central venous catheter skin site, antimicrobial locks, and infection prevention programs are also considered.

Purpose of the study. Using the example of a cardiac surgical hospital, to study the possibility of detecting the activation of the epidemic process of purulent septic infections (GSI) based on the results of comparing the current incidence rate with the ordinary.

Materials and methods. Cases of GSI in operated adult patients of a cardiac surgery hospital were actively identified based on examination of medical histories using standard case definitions. The control (ordinary) level was considered to be the incidence rate not exceeding the upper limit of the median monthly indicators for 2018–2022. The current monthly incidence in 2023 was compared with the resident.

Results. The average monthly median incidence of GSI in adult patients of a cardiac surgical hospital for 2018–2022 was 16,1, the upper confidence limit of the median was 23,2 per 1000 operated patients. In the analyzed 2023, the excess of the actual incidence of GSI over the ordinary was detected in July. The increase in morbidity occurred due to an increase in the number of cases of infection of the surgical intervention area due to a violation of the standard procedure for dressing the surgical wound of operated patients.

Conclusion. The identification of the activation of the epidemic process of nosocomial GSI during operational monitoring is possible based on the results of comparing the current incidence rate with the ordinary, calculated on the basis of the median monthly indicators of the previous multi-year period.

West Nile fever (WNF) is a zoonotic infection caused by West Nile virus (WNV), which belongs to the family Flaviviridae and the genus Flavivirus. The virus is transmitted to humans through the bites of infected mosquitoes, most often from the genus Culex. The relevance of this infection remains at a high level due to its worldwide spread and damage to the central nervous system. Also, methods of specific diagnosis and treatment of this disease have not been developed. Research on the immune system can help solve these problems. The immune response to West Nile virus is a complex interaction of innate and adaptive mechanisms. While the immune system usually effectively controls infection, in some cases excessive inflammation or an insufficient immune response can lead to severe consequences, including damage to the central nervous system. Understanding these mechanisms is of key importance for the development of vaccines and therapeutic approaches to the treatment of WNF.

The time spent studying at school and then at university is quite a long and time–consuming process that requires a lot of money. The problem of maintaining the proper functional level of students is especially relevant, since the body's functioning indicators are closely related to the ability to adapt to the learning load and directly affect health indicators.

The purpose of the study is to study the indicator of the total effect of regulation among university students, taking into account gender and age gradations and the course of the educational process in order to predict the indicator and manage risk factors.

Materials and methods of research. The study involved 208 university students. The group of subjects was distributed taking into account the gender and age composition and the course of study. The control group consisted of representatives of similar gender and age composition, who had professions without harms and were not involved in the educational process at the time of the study. The method of variational heart rate monitoring was used as a methodological approach. The essence of the method is the possibility of computer processing of electrocardiographic examination data. The work was carried out on the basis of a software product developed by the staff of the Institute of Biomedical Problems of the Russian Academy of Medical Sciences. Methods of nonparametric and parametric statistics were used for statistical data processing.

Results. The results of the analysis of the regulation effect indicators in medical university students showed that the most common type of heart rate (HR) is the cardiac norm, observed in 40.6% of participants. Severe tachycardia occurs in 21.7% of students, moderate tachycardia is detected in 25.6% of students. Normocardia occurs in 36.3% of first-year students and 39.4% of third-year students. Severe tachycardia is 21.7% in men and 21.8% in women, moderate tachycardia is more common in women and is 31% compared with 20.6% in men. A more detailed analysis of heart rate indicators in female students of different age groups (by course) showed that the level of tachycardia decreases with increasing curriculum. Comparative gender analysis showed that in the control group, normocardia was observed in 70% of cases in women and in 66.6% of cases in men.

Conclusions. An analysis of the indicators of the total effect of regulation according to the course of the study, age, gender, showed that the indicators encountered are normo- and tachycardia. The results demonstrate the importance of taking gender and age into account when diagnosing heart disease.