Listeriosis is a saprozoonotic natural anthropurgic infectious disease caused by Listeria monocytogenes, with multiple pathways and factors of its transmission, characterized by pronounced clinical polymorphism from carriage and subclinical to severe generalized forms, meningitis and meningoencephalitis, and high mortality among newborn children and individuals with immunodeficiency. Express diagnostics of listeriosis is based on the use of immuno-chemical (immunodiffusion reaction, enzyme immunoassay) and molecular genetic (polymerase chain reaction) methods. In the practice of laboratory diagnostics, serological methods for the study of listeriosis remain in high demand for verifying the clinical diagnosis. One of the specific, reliable and available serological methods for laboratory diagnostics of causative agents of infectious diseases remains the agglutination test (AT), to conduct which, listeria agglutinating serum is required. Obtaining diagnostic agglutinating listeria serum with a high level of diagnostic sensitivity and specificity will allow timely identification of the pathogen in the test tube AT and on glass, based on the specific interaction of the antigen with the anti-body, with the formation of agglutinate visible to the naked eye. In this study a scheme has been developed for immunization of animal producers to obtain diagnostic listeria agglutinat-ing serum. Evaluation of the clinical efficiency of two series of the serum was carried out based on the indices of diagnostic sensitivity with different serovariants of L. monocytogenes and diagnostic specificity with closely related and heterologous strains in the test tube AT and on glass. During the study of 25 strains of L. monocytogenes serogroups I and II (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4c, 7) isolated on the territory of the Russian Federation from various sources (clinical material, food products, wastewater), the serum titer did not differ and amounted to 1:800 in the course of in vitro agglutination reaction; a positive result was obtained on glass in 100% of cases. The assessment of the statistical reliability of the ob-tained test results was at least 89 % with a statistical significance of 95 %, which indicates a high diagnostic efficiency of the serum. In order to establish intra-stage convergence and inter-series reproducibility of studies, two probabilities of binomial distributions were compared. The convergence of staged studies for all positive samples has been proven. Based on the re-sults obtained, listeriosis serum can be used as a medical preparation for in vitro diagnostics of the causative agent of listeriosis.

The causative agent of listeriosis refers to pathogens when clinical diagnosis is difficult due to the polymorphism of the manifestation of the disease. In this regard, the use of express methods of laboratory diagnostics, which include the agglutination reaction, is an urgent need for rapid diagnosis and timely treatment. To obtain an experimental diagnostic listeriosis agglutinating highly specific serum, a sufficient volume of immunogen is required, the source of which is the inactivated bacterial mass of Listeria monocytogenes 766. The development of a bacterial nutrient medium for the cultivation of listeriosis microbe is caused by need to ensure high growth of listeria biomass in a short time. Pacific herring (Clupea pallasii), pollock (Gadus chalcogrammus), roach (Rutilus rutilus) and European squid (Loligo vulgaris) were used as raw materials for obtaining hydrolysates. Comparative physico-chemical studies of tested nutrient bases have shown that optimal basis of nutrient medium is pancreatic hydrolysate of roach, in which the maximum indicators of enzymatic process speed, the content of amine nitrogen, stable preservation of acidic properties for a long time are determined. Using the method of NMR spectroscopy, the amino acid composition of the nutrient medium for accumulation of listeria biomass was established, which is represented by alanine, valine, threonine, arginine, lysine, leucine, methionine, histidine, tyrosine and tryptophan and the amino acids phenylalanine and glycine, which are most important for the growth of listeria. It was found that nutrient medium based on pancreatic hydrolysate of roach had advantages over other bases (Pacific herring, pollock and European squid pancreatic hydrolysates) in terms of germination, sensitivity and efficiency, growth rate of the nutrient medium for listeria cultivation, while maintaining the typical listeria cultural-morphological, biochemical and serological properties. It has been established that effectiveness of experimental nutrient medium f, designed by specialists of laboratory of nutrient media of Irkutsk Anti-Plague Institute, is not inferior to such commercial medical products as GRM-agar and meatpeptone agar. Experimental results confirmed the ability of culture medium for the cultivation of listeria to preserve the biological properties of test strain L. monocytogenes 766 (collection of pathogenic bacteria of the Irkutsk Anti-Plague Institute) for one year. Based on the data obtained, we concluded that the high growth rates of listeria on proposed nutrient medium were achieved through use of pancreatic roach hydrolysate and components optimal concentrations that stimulate the growth of listeria, providing a significant accumulation of bacterial mass in shortest possible time.