Abstract
The aim of the study was to investigate the prevalence and resistance of biofilm-forming Salmonella strains on poultry farms in Kazakhstan, Latvia, and Turkey. During the study, samples of faeces, tissues (liver and intestines) and water from drinkers were collected and analysed from January to December 2023. Salmonella strains were isolated and identified using standard microbiological methods. A total of 150 Salmonella strains were isolated and identified, of which 90 strains were obtained from faecal samples, 40 from tissue samples and 20 from water samples. The distribution of strains by country showed that in Kazakhstan, Latvia and Turkey, the largest number of strains were isolated from faecal samples. Of the 80 Salmonella Enteritidis strains, most showed the ability to form biofilms, as determined by the crystal violet method, with subtypes SE1 and SE2 showing the highest propensity for biofilm formation. Among the Salmonella Typhimurium strains, a significant biofilm formation ability was found in the ST1 subtype. Antibiotic resistance was determined using the disc diffusion method. The biofilm-forming strains showed higher antibiotic resistance compared to the non-biofilm-forming strains. Of the 150 strains isolated, 105 showed resistance to at least one of the antibiotics tested, with the highest level of resistance among Salmonella Typhimurium strains. Correlation analysis revealed a significant positive relationship between the level of biofilm formation and antibiotic resistance. The results demonstrate the need to introduce the development of new methods of control and prevention of infections on poultry farms, which would take into account the peculiarities of biofilm formation and antibiotic resistance of certain strains