Obtaining and Efficiency Assessment of Diagnostic Agglutinating Serum for Identifying the Causative Agent of Listeriosis
Authors:   Irkutsk Antiplague Research Institute of Siberia and Far East, Khaptanova N. M. , Andreevskaya N. M. ,   Irkutsk Antiplague Research Institute of Siberia and Far East, Konovalova Zh. A. ,   Irkutsk Antiplague Research Institute of Siberia and Far East, Gefan N. G. ,   Irkutsk Antiplague Research Institute of Siberia and Far East, Luk'yanova S. V. ,   Irkutsk Antiplague Research Institute of Siberia and Far East, Ostyak A.S. ,   Irkutsk Antiplague Research Institute of Siberia and Far East, Kartsev N. N. ,   Research Center for Applied Microbiology and Biotechnology, Borzenkov V. N. ,   Research Center for Applied Microbiology and Biotechnology, Balakhonov S. V. ,   Irkutsk Antiplague Research Institute of Siberia and Far East
Published: March 2022

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.