Vol 100, No 1 (2023)

Relevance. Candida infection remains relevant due to the wide spread of antimycotic-resistant strains of Candida fungi, especially among immunocompromised individuals. It was previously discovered that the Candida spp. microbial community in the biotope of the oropharynx of HIV infected patients is characterized by a certain architecture: they can be present in this biotope in the form of a monoculture or as association of co-isolates. It has been suggested that the architecture of the Candida microbial community may influence their resistance to antimycotic drugs.

Purpose — a comparative study of the association between the architecture of the C. albicans microbial community in the oropharynx of HIV infected patients with oropharyngeal candidiasis and their sensitivity to antimycotic drugs.

Materials and methods. A microbiological study of 52 isolates of Candida fungi (C. albicans, C. glabrata, C. tropicalis and C. krusei) from the oropharynx of 31 HIV infected patients with clinical manifestations of oropharyngeal candidiasis aged 20 to 69 years with almost equal gender distribution was carried out. In the form of monocultures, 18 isolates were isolated, while 34 were identified as co-isolates, which formed 16 homogeneous communities that included strains of the same species, and 18 heterogeneous ones that consisted of fungi of various species.

Results. It was found that heterogeneous communities of C. albicans were markedly distinguished by sensitivity to antimycotic drugs, in particular, by low sensitivity to imidazoles. Homogeneous communities practically did not differ from monocultural ones. The general properties of the C. non-albicans population were largely similar to those of C. albicans, but were characterized by lower heterogeneity in response to antimycotic drugs.

Conclusion. The architecture of the community of C. albicans isolated from the oropharynx of HIV infected patients with clinical manifestations of oropharyngeal candidiasis affects their sensitivity to antimycotic drugs. When selecting effective antimycotic therapy for such patients, it is necessary to take into account the structure of the Candida spp. community in the oropharynx.

Introduction. Identification of the groups of the population most susceptible to infection with hepatitis A virus (HAV) is a key component for the regulation of anti-epidemic measures during the activation of the epidemic process.

The aim — аssessment of the herd immunity to hepatitis A (HA) among different age groups of the population of the Republic of Tatarstan.

Materials and methods. The analysis of the HA incidence of from 2006 to 2021 and the study of herd immunity to HA among 6,553 persons from different age groups that were not vaccinated against HA were carried out. Participants with protective concentrations of antibodies to HAV of 20 mMU/ml or more were considered as seropositive.

Results. The analysis showed a low intensity of the epidemic process in general (3.6 ± 0.3^о/_оооо), while the HA incidence among children and adults was significantly different, with incidence rates 2.3 times higher in the first group (6.9 ± 0.9 and 3.0 ± 0.3^о/_оооо, respectively). The epidemic process is determined by persons aged 15–17 years (8.2 ± 2.5^о/_оооо), 3–6 years (7.0 ± 1.9^о/_оооо, 7–14 years (6.2 ± 1.3^о/_оооо), the incidence among these age groups in all observed years remained the highest. In general, the proportion of seropositive children was 32.1 ± 1.0%. Among adults, anti-HAV IgG antibodies in a protective concentration was detected in 68.2 ± 0.7%. The highest frequency of anti-HAV IgG positive samples was observed among persons aged 50–59 years — 89.4 ± 1.1%, in age group 40–49 years — 73.5 ± 1.2%, in age group 30–39 years — 65.5 ± 1.3%, and in age group 20–29 years — 48.2 ± 1.6%. In total, 56.9 ± 0.6% of the examined individuals had protective antibodies to HAV. The detection rates of anti-HAV IgG antibodies were significantly different in all age groups (p < 0.05).

Introduction. Registration of regular epidemic outbreaks of mumps infection among young people, difficulties in the clinical diagnosis of the disease, the presence of specific clinical manifestations in adults with a severe course of infection make it necessary the improvement of the quality of diagnosis of the disease.

The aim of the work is to develop a standard definition of a clinical case of mumps and to conduct a comparative assessment of the effectiveness of the diagnostic test systems used for mumps diagnostics based on the determination of their sensitivity and specificity.

Materials and methods. To develop a standard definition of a clinical case of mumps based on ten combined clinical and laboratory parameters, a mathematical model was built using the logistic regression method. The study included 84 patients with mumps infection (main group) and 66 patients with non-epidemic sialoadenitis (comparison group). For a comparative evaluation of the diagnostic systems VectoParotitis-IgM, VectoParotitis-IgG, ELISA-Mumps-IgM, ELISA-Mumps-IgG, Anti-Mumps Virus ELISA-IgM, and Anti-Mumps Virus ELISA-IgG, a blood serum samples from patients (n = 41) with a diagnosis “mumps?” were tested in dynamics to assess their sensitivity, specificity, and diagnostic effectiveness.

Results. The clinical symptom “dry mouth” increased the chance of diagnosing mumps by 13.7 times, the presence of bilateral lesions of the salivary glands — by 6.5 times, the increase in the level of diastase in the urine — by 3.2 times. The coefficient of determination R² was 61.1; the sensitivity was 93% and the specificity — 67%; p < 0.001. Diagnostic effectiveness of “Anti-Mumps Virus ELISA-IgG” test system was 84.4%, ELISA-Mumps-IgG — 87.2%, and "VectoParotitis-IgG" — 88.5%.

Conclusions. Based on the combination of following clinical symptoms observed simultaneously in patient, of the general weakness, dry mouth, bilateral lesions of the salivary glands, an increase in the level of diastase in the urine, it is possible to establish a clinical diagnosis of mumps with a probability of 81%. The highest diagnostic effectiveness of domestically manufactured test systems for quantitation of IgG antibodies to mumps virus in sick people has been demonstrted.

Introduction. The assessment of specific IgG antibodies to RBD Spike SARS-CoV-2 and their quantitation permit to calculate the intensity of immunity to COVID-19, i.e. to determine the level of immunity to infection, the risk of infection, the severity of the disease, as well as the ability to prevent death. Meanwhile, the protective level of antibodies is not determined. Therefore, determining the nature of immunity and quantitation of IgG antibodies to RBD Spike SARS-CoV-2 make it possible to assess the effectiveness of preventive measures and correct them in a timely manner.

The aim is to determine the presence of IgG antibodies to RBD Spike SARS-CoV-2, their concentrations, and the nature of humoral immunity in different age and occupational groups of employees in a closed-type hospital after the completed vaccination with "Gam-Covid-Vac" vaccine.

Materials and methods. The blood sera of 310 members of medical staff who received a full course of immunization with the "Gam-Covid-Vac" vaccine were tested using "SARS-CoV-2-ELISA-IgG" kit according to instructions provided in 21.20.23-004-28597318-2020, RU No. RZN 2021/15898. IgG antibodies to RBD Spike SARS-CoV-2 were quantitated against WHO standard NIBSC 20/136.

Results. Specific IgG antibodies to RBD Spike SARS-CoV-2 were found in 92.9% of the examined individuals, including 67.4% having hybrid immunity (both vaccine- and infection- induced), and 25.5% having post-vaccination immunity after immunization with the "Gam-Covid-Vac" vaccine; 7.1% participants were nonimmune. A higher level of IgG antibodies to RBD Spike SARS-CoV-2 was detected in the group of individuals with hybrid immunity (p < 0.01). Only 11.6% of employees had a protective antibody level of more than 300 BAU/ml.

Discussion. Most employees with hybrid immunity were identified in the older age groups and in the junior medical staff. The results of this serological study, taking into account the age and professional aspects, can serve as the basis for adjusting preventive measures in medical institutions.

Introduction. Influenza A virus is the cause of epidemics and pandemics that severely affect the health and socioeconomic status of the world's population. The need to develop new methods of etiotropic therapy, and the increasing ability of viruses to counteract the antiviral drugs makes extremely relevant the search for new pharmacologically active substances and the subsequent study of their medicinal properties.

The aim of the study is to conduct research into the antiviral properties of melanin obtained from the pharmaceutical chaga mushroom in relation to different subtypes of the influenza A virus.

Materials and methods. A sample of water-soluble melanin from Inonotus obliquus obtained by alkaline hydrolysis and dried at 40°C was tested for toxicity and antiviral activity. The commercial anti-influenza drug Tamiflu^® was used as a reference drug. Statistical processing of the obtained data was carried out according to the Spearman-Kerber method.

Results. Inonotus obliquus melanin (sample 20-24) toxicity markers, such as a maximum tolerable concentration (MTC) of 237.0 µg/mL, and a 50% cytotoxic concentration (CC₅₀) of 153,45 µg/mL were established for MDCK cell culture. The assessment of antiviral activity of test sample against three subtypes of the influenza A virus (H5N1, H3N2 and H1N1pdm09) demonstrated a decrease in the infectivity of the influenza virus by 2.5–3.5 lg with 50% virus-inhibiting concentrations (IC₅₀) of 1.55–9.52 µg/mL. Based on the obtained values of CC₅₀ and IC₅₀, the selectivity indices (SI) of the sample were calculated, characterizing its prospects for further research.

Conclusions. Melanin obtained from the pharmaceutical chaga mushroom showed the highest activity against the strain of the human pandemic influenza virus A/California/04/2009 (H1N1)pdm09, caused a decrease in its infectivity by 3.5 lg and had an IC₅₀ of 1.6 µg/ml. The obtained results indicate the prospects for creating an antiviral drug based on Inonotus obliquus melanins against the influenza virus.

Bacteriophage endolysins are a biologically active substances that play a specific role in the release of phage progeny by degrading the peptidoglycan of the host bacterium. In the light of antibiotic resistance, endolysins are considered as alternative therapeutic agents because of their exceptional ability to target bacterial cells.

Aim — summarization of the data on the biology, structure, mechanisms of action of bacteriophage endolysins, as well as on preparations based on them, which are at different stages of research.

The results of studies of bacterial endolysins over the past 20 years were searched using the Internet resources PubMed, Web of Science, Scopus in English for the keywords: lysin, bacteriophages, holin, antibiotic resistance.

The analysis of literature data showed that the structure of phage endolysins of Gram-positive and Gram-negative bacteria differs from each other and reflects differences in their architecture due to variation in the cell wall composition of these two major bacterial groups. Depending on the cleavable bond in peptidoglycan, endolysins can be divided into at least five different groups: glycosidases (two groups — aminidases and muramidases), endopeptidases, specific amidogyrolases, and lytic transglycosylases. To date, endolysins effective against a number of pathogens have been studied, including Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus, Mycobacterium spp., Pseudomonas aeruginosa, etc. A number of studies have shown the therapeutic potential of endolysins in combating antibiotic-resistant infections.