научно-исследовательский институт бруцеллеза и туберкулеза животных Российской академии сельскохозяйственных наук», Омск Полученные экспериментальные данные свидетельствуют о том, что разработанные сухие питательные среды на основах печеночного настоя и гидролизата сороги обладают высокой чувствительностью, полностью ингибируют рост бруцелл в S-форме и могут быть использованы для выделения, культивирования и накопления бруцелл в L-форме при бактериологической диагностике бруцеллеза. Питательные среды не нуждаются в корректировке рН, не требуют фильтрации и автоклавирования, удобны при транспортировке, что позволяет использовать их для работы в стационарных и полевых условиях.

The review presents data on the antigenic structure and the current classification of epidemically significant serovariants of Listeria. Description of species-specific properties of serovariants of Listeria, which may be common for two or more species, and common antigens with staphylococci and typhoid and paratyphoid bacteria, are given. It has been shown that only the antigenic scheme of Listeria monocytogenes is of practical interest for medical microbiology. Importance of serotyping in the epidemiological analysis to determine the source of infections and ways of its spreading has been determined. Differences in the designation of serovariants in the diagnosis of listeriosis in medical practice are observed. High level of adaptive properties of Listeria, its ability to reproduce in an abiotic environment, including food, susceptibility of immunodeficient individuals, prevalence of food pathway of infection pose a significant danger of increased sickness rate with listeriosis. Serological diagnostics of Listeria has not been developed in detail, and the existing serological methods are aimed at identifying specific antibodies to listeria. Advantages of the serological method include: quick results and the possibility to study any biological material. Currently available serological methods have a number of disadvantages: low reliability of results and low specificity of the study. The most promising method for identification of a serological group of cultures, according to the world classification, is the multiplex PCR method, based on the correlation between the serogroup of an isolate and the presence of specific open reading frames in its genome.

The objective is to perform a comparative evaluation of the pancreatic hydrolysates prepared from fish and squid to determine the optimal culture medium for Listeria monocytogenes.Materials and methods. The following raw materials were used in the study: Pacific Herring (Clupea pallasii), Alaska Pollock (Gadus chalcogrammus), Common Roach (Rutilus rutilus lacustris), European Squid (Loligo vulgaris). The raw materials were subjected to enzymatic hydrolysis using the pancreas (according to Hottinger). A study of the physicochemical properties of pancreatic hydrolysates (content of free amino nitrogen (FAN), acidity of fish hydrolysates, the amino acid composition) was carried out.. The specific activity of nutrient media during the cultivation of the test strain L. monocytogenes 766 was assessed by a complex of microbiological methods.Results and discussion. The highest content of FAN at the end of enzymatic hydrolysis was observed in the pancreatic hydrolysate of the common roach (6%), the acidity of the hydrolysate remained stable from 6th to 13th day of the hydrolysis process (pH 7.2). Pancreatic hydrolysate of the common roach contained a number of amino acids that are most essential for the growth of Listeria. An assessment of the biological properties of nutrient media prepared on the basis of the obtained hydrolysates demonstrated that the best results in terms of sensitivity and germination of L. monocytogenes 766 showed a nutrient medium based on the pancreatic hydrolysate of the common roach. During the cultivation of L. monocytogenes 766 the test strain retained its morphological and cultural properties and did not show signs of dissociation.Conclusion. The research results have shown that the pancreatic hydrolysate of the common roach is a promising protein basis for the construction of an experimental environment for listeria.

Background. To obtain reliable results of laboratory studies on the identification of Listeria, the presence of certified diagnostic agglutinating Listeria sera is required. An important step in the manufacturing process of such medical devices for in vitro diagnostics requires effective nutrient media for the accumulation of listeriosis microbe. Aim of the research. To develop an effective nutrient medium for the accumulation of bacterial mass of Listeria. Materials and methods. The object of the study was an experimental culture medium for Listeria cultivation. As a control, we used nutrient agar for the cultivation of microorganisms (fish meal hydrolysate, FMH-agar) and meat-peptone agar with 1 % glucose (MPA with 1 % glucose). The specific activity of nutrient media during cultivation of the test strain Listeria monocytogenes 766 was evaluated using a complex of microbiological methods. Results. The optimal base of the nutrient medium for Listeria cultivation has been selected: pancreatic hydrolysate of river magpie fish (Rutilus rutilus lacustris) and hydrolysate of meat water production waste. The qualitative and quantitative composition of the nutrient medium has been developed, its physical, chemical and biological properties have been studied. It was found that after 24 hours of incubation at 37 °C, the nutrient medium provided the growth of typical Listeria colonies. The germination rate was 85 %, which is higher compared to the growth of the culture on MPA with 1 % glucose and GRM agar by an average of 21 % (p < 0,05). Conclusion. The experimental culture medium for Listeria cultivation provided growth of colonies of the test strain L. monocytogenes 766 with the preservation of characteristic cultural, morphological and biochemical properties, and, in terms of germination and growth rate, exceeded the control media. The developed nutrient medium provides effective growth of Listeria and can be used as a medium for the accumulation of microbial mass.

Background. Pseudotuberculosis remains a serious healthcare problem, which determines the expediency of developing the express methods for its early diagnosis. To detect the pathogen, we designed test system for dot-immunoassay (DIA) based on antibodies labeled with silver nanoparticles (SNPs) isolated from hyperimmune rabbit serum obtained against killed cells of  Yersinia pseudotuberculosis of O:1b serovariant.The aim. To assess the possibility of using dot-immunoassay for express identification of Y. pseudotuberculosis cultures isolated from clinical material and environmental objects at the initial stage of bacteriological study during laboratory diagnosis of the disease.Methods. We used the materials from the outbreak of pseudotuberculosis in the Krylovskaya Boarding School of the Bakcharsky district of the Tomsk region in 2021. Specific antibodies from hyperimmune rabbit sera obtained against Y. pseudotuberculosis 3704 particulate antigen of O:1b serotype were labeled with SNPs and used in DIA on nitrocellulose membranes with visualization of reaction results with a solution of a physical developer. The presence of the causative agent of pseudotuberculosis in the test material was inferred by the formation of gray spots of different intensity (from 4+ to 1+).Results. All Y.  pseudotuberculosis strains isolated using bacteriological method on  the second day of the study from clinical material obtained from sick people and environmental objects were detected in DIA at concentrations ≥ 3.1 × 104 microbial cells per milliliter (m.c./ml).Conclusion. The designed test system for dot-immunoassay using SNPs as a marker of specific antibodies for the detection of Y.  pseudotuberculosis in cultures isolated from swabs from vegetables and clinical material from patients, including those  with  mixed infection, allows us to  detect a specific corpuscular antigen with a high sensitivity (≥ 3.1 × 104 m.c./ml), providing express identification of isolated cultures at the initial stage of bacteriological study.