Introduction. One of the main objectives of the agro-industrial complex is supplying the population of the Russian Federation with the high-quality raw materials and products of animal husbandry. In the frame of this activity, poultry farms are implementing innovative technologies of intensive poultry farming, as well as carry out regular prophylactic work to ensure epizootological safety of poultry rearing. The most dangerous infectious diseases for chickens are tuberculosis, Newcastle disease, leucosis, escherichiosis, avian influenza, infectious laryngotracheitis, Marek's disease and others. In case of outbreak, these diseases cause mass poultry mortality inducing major economic damage to the poultry industry.

In recent years, the interest of the researchers to animal diseases caused by opportunistic microflora has raised [1][2][3]. In the context of decreased resistance of the organism to infection, violation of veterinary, animal hygiene, sanitary rules for rearing animals, there occur diseases caused by concomitant microflora — streptococcosis, staphylococcosis, escherichiosis, enterococcosis, salmonellosis [4][5]. According to the data obtained by many researchers, agricultural poultry can infect other species of animals, as well as humans, therefore, it is necessary to conduct timely monitoring of microbes and detect pathogenic species to prevent infected products from reaching animals and people [6][7][8]. The use of antibiotics for treatment of sick animals without checking their efficacy against the isolated microorganisms, violation of the dosage and course of therapy lead to rapid adaptation of microbes to unfavourable factors and emergence of the new variants of pathogens, especially of E. coli. Therefore, to prevent infectious diseases, the mandatory action plan of each poultry farm should include quick high-quality diagnostics and various veterinary and sanitary procedures to prevent contamination of animal husbandry raw materials and infecting susceptible animals and people [9][10]. The aim of the article is to study and analyse the pathogens isolated from pathological material from chickens reared in the Krasnodar Territory and the Republic of Adygea to ensure efficient organisation of the anti-epizootic, preventive and therapeutic measures.

Materials and Methods. The research was conducted at the Department of Microbiology, Epizootology and Virology Department, at Territory-level Veterinary Laboratory of Kropotkin and at various poultry farms of the Krasnodar Territory and the Republic of Adygea in the period of 2019–2023. The objects of the study were agricultural poultry (chickens) and isolates of microorganisms (pathological material) from sick and dead birds. A total of 2018 samples were examined. A comprehensive examination was carried out taking into account the epizootological indicators, clinical signs in poultry, pathological changes and the results of laboratory tests as per the isolated pathogen.

Laboratory diagnostics was based on the use of bacteriological tests that enable the isolation of a pathogen, its identification, determination of the type, serotype, pathogenicity of a microorganism [11–14]. The diagnostics was carried out in compliance with the current regulatory documents adopted by the Veterinary Authorities of the Russian Federation on bacteriological methods of examining the pathological material (from the heart, liver, spleen, intestinal contents, bone marrow) obtained from fallen and forcedly killed birds.

The study on the isolation of the pathogen of colibacillosis (escherichiosis) was carried out in compliance with the “Methodological Guidelines for the Bacteriological Diagnostics of Colibacillosis (Escherichiosis) in Animals”, approved on July 27, 2000 by the Deputy Head of the Veterinary Medicine Department of the Ministry of Agriculture and Food of the Russian Federation.

The study on enterococcosis and mixed intestinal infection was carried out in compliance with the “Methodological Guidelines for the Bacteriological Diagnostics of Mixed Intestinal Infection in Young Animals Caused by Pathogenic Enterobacteria” No. 13-7-2/1759 of October 11, 1999 adopted by the Veterinary Medicine Department of the Ministry of Agriculture and Food of the Russian Federation.

The study on staphylococcosis was carried out in compliance with the “Methodological Guidelines for Laboratory Diagnostics of Staphylococcosis in Animals” approved on June 30, 1987 by the Head of the Main Veterinary Directorate of the State Agro-Industrial Committee of the USSR.

The study on the isolation of pathogens of streptococcosis was carried out in compliance with the “Methodological Guidelines for Laboratory Diagnostics of Streptococcosis in Animals” approved on September 25, 1990 by the Deputy Head of the Main Veterinary Directorate with the State Veterinary Inspectorate under the State Commission of the USSR Council of Ministers for Food and Procurement.

For the study on salmonellosis, “Methodological Guidelines MU 4.2.2723–10 for Laboratory Diagnostics of Salmonellosis, Detection of Salmonella in Food Products and Environmental Objects” published by the Federal Centre for Hygiene and Epidemiology of Rospotrebnadzor in 2011 was used.

Standard laboratory equipment was used to conduct the research: a thermostat at 37 °C, and a microscope (“Biolam”, Russia) [15][16]. Bacteriological tests included determination of the morphological, tinctorial, bacteria culture, and serological indicators in the isolated microorganisms [17–20].

The epizootic situation was assessed based on the analysis of disease outbreaks registered in the record books of the farms.

Research Results. During laboratory study of the pathological material from poultry from the various farms of the Krasnodar Territory and the Republic of Adygea in the period of 2019–2023, 5 pathogens of infectious diseases were isolated: escherichiosis (E. coli), enterococcosis (E. faecalis), staphylococcosis (St. aureus), streptococcosis (Str. pneumoniae), mixed microflora (E. coli, E. faecalis), salmonellosis (S. pullorum) (Fig. 1, Table 1).

A significant number of different E. coli serotypes are known. Intestinal bacterium (E. coli) has different types of antigens: O-antigen (somatic), K-antigen (capsular), H-antigen (flagellar), some of them are pathogenic, others are non-pathogenic. Of the pathogenic E. coli from chickens, 26 serotypes of somatic O-antigen were isolated, the most common were serotypes 1, 2, 9, 15, 20, 27, 33, 45, 55, 78, 139 (Fig. 2, Table 2).

The pathogenic microorganisms E. coli, E. faecalis, St. aureus, Str. pneumoniaе, S. pullorum detected as a result of monitoring, both pure culture and mixed culture with other microbes, caused the following infectious diseases in chickens: escherichiosis (41.43%), enterococcosis (26.51%), staphylococcosis (18.04%), streptococcosis (12.29%), mixed intestinal infection (escherichiosis and enterococcosis) — 1.64%, salmonellosis (0.1%).

Discussion and Conclusion. Based on the results of the conducted monitoring, a tendency towards improvement of the epizootic situation at poultry farms of the Krasnodar Territory and the Republic of Adygea can be noted compared to the situation five years ago. Nevertheless, the percentage of chickens infected with escherichiosis, streptococcosis, staphylococcosis and enterococcosis remains quite high. Due to high variability of the pathogen causing escherichiosis (E. Coli) (26 serotypes have been isolated over the past 5 years), it can infect humans through raw materials and products of animal husbandry. In this regard, the management of poultry farms is strongly recommended to take timely measures on diagnostics and prophylaxis of the above infectious diseases, as well as to treat poultry located in the unfavorable places after mandatory determination of the isolated pathogenic microorganisms’ sensitivity to antibiotics. At the same time, the biological features of these types of microbes must be taken into account when developing the efficient technology for rearing poultry and animals at poultry and husbandry farms.