Usually, antibiotic resistance of microorganisms occurs as a result of long-term treatment and prophylactic use of antibiotics. Environmental exposure to puppies’ food base also contributes to the development of antibiotic resistance. It is imperative to investigate the sensitivity of cultures to antibiotics during isolation in order to determine their resistance and provide recommendations for the use of specific drugs. The purpose of the study was to determine the sensitivity of E. coli to antibiotics, as well as the overall bacteriological contamination in the fecal samples of two experimental groups of puppies treated with the probiotic preparation in their main diet. To achieve the goal, generally accepted clinical, microbiological and bacteriological research methods were used, in particular, the disco-diffuse method using standardized antibiotic discs manufactured by ASPECT LLC (Ukraine) to assess antibiotic resistance to antibiotic resistance on the Müller-Hintot medium using API-20E-strips (bioMerieux, France) according to the Kibri-Bauer method (disco-diffuse method). In a study of the probiotic effect on the intestinal microflora of puppies, it was found that the use of a probiotic had a significant effect on bacterial contamination of fecal samples of experimental groups of puppies. E. coli cultures were tested for sensitivity to 7 antibiotics. Due to the size of the zones of growth retardation of microorganisms, it was possible to determine the sensitivity of the culture to each antibiotic. The results of the study show that the cultures were extremely sensitive to azithromycin as well as nitrofurantoin and chloramphenicol (according to EUCAST standards). The addition of probiotic symbiotic preparations Bacillus subtilis and Bacillus licheniformis to the diet of dogs improved the intestinal microflora in 71.42% of combinations of conditions and antibacterial substance.

Keywords: resistance, Escherichia coli, bacterial susceptibility, bacterial contamination, antibiotics, probiotic, dogs.