In vitro detection of antagonistic activity levels of Enterococcus faecium isolates and selection prospective probiotic strains

Abstract

In the modern conditions of the development of commercial poultry farming, the development of new biological
prophylactic drugs for the correction of microbiocenosis and the improvement of non-specific immunity of poultry
is given priority. The materials of the article present the results of studies of the antagonistic properties of 5 isolates
of Enterococcus faecium, isolated from the caecum of the large intestine with contents collected from chickens and
broiler chickens from poultry farms of Ukraine for active monitoring in accordance with the state program of the
Procedure for Supervision (Active Monitoring) of Antimicrobial Resistance zoonotic and commensal bacteria in
veterinary medicine and identified to species. The studies were carried out by two diffusion methods - delayed
antagonism and agar blocks in order to confirm the reliability of the obtained results. 2 strains of Enterococcus
faecium – Efm-3 and Efm-5 were found to have very high and high levels of antagonism after the interaction of the
strains with gram-negative and gram-positive test bacteria Escherichia coli ATSS 25922 (diameters of growth
inhibition zones 39.4±1.3/36.4± 0.3 and 42.2±2.7/39.4±2.7 mm according to strains and methods), Pseudomonas
aeruginosa ATCC 15442 (29.0±1.3/28.4±0.7 and 29, 2±1.3/39.4±2.7), Salmonella typhimurium ATCC 29630
(17.2±0.7/17.2±1.7 and 28.2±0.7/28.6±0, 7) and Staphylococcus aureus ATCC 6538 (28.2±0.07/28.4±0.7 and
35.2±0.7/34.2±0.17), which are in the range of values of high antagonism. Enterococcus faecium Efm-3 and Efm-5
strains were selected as promising probiotic microorganisms due to their avirulent properties and high level of
antagonistic activity. The obtained data confirm the possibility of correcting the immune response with the help of
developed complex probiotic preparations with selected promising strains of Enterococcus faecium in the
composition, aimed at normalizing the intestinal microflora, strengthening the body's immune functions, increasing
the parameters of poultry preservation and the quality of the obtained products.