Horiuk Y. Justification, development and use of bacteriophage for the treatment of cows suffering from mastitis

An intracisternal drug Fagomast has been developed for the prevention and treatment of cows with mastitis, as an alternative to antibiotics for obtaining environmentally safe milk. Its toxico-pharmacological properties, effects on the organism of experimental laboratory animals and therapeutic effectiveness during the treatment of cows with various forms of mastitis have been studied. The pharmacological effectiveness of the use of Fagomast in the treatment of cows with subclinical mastitis was 92.1 %, while S. aureus was not isolated 5 days after the end of the treatment, and the number of somatic cells decreased by 16.8 times to 250.1±22.3 ths/cm3. Pharmacological efficiency of treatment of cows with clinical form of mastitis was 71.4 %. The conducted studies confirm the high pharmacotherapeutic effectiveness of the developed drug Fagomast for the treatment of cows with staphylococcal mastitis and will allow to increase the environmental friendliness of the obtained products and minimize restrictive measures regarding the production of dugs when using antibacterial drugs. It has been established that among the causative agents of both acute and chronic forms of mastitis, S. aureus strains have the greatest film- and toxin-forming ability, in addition, they represent a large reservoir of genes for resistance to antimicrobial drugs, including resistance to methicillin, which in the process of production of milk can contaminate it and be transmitted to humans. It has been found that drugs based on industrially produced bacteriophages are ineffective against cultures of Staphylococcus aureus isolated from dairy products and from cows suffering from mastitis. The biological properties of the highly lytic bacteriophage strain Phage SAvB14 have been isolated and studied. It has been established that it exhibits high lytic activity against Staphylococcus aureus var. bovis, forms transparent plaques with clear edges 1 ‒ 2 mm in size, is resistant to high temperatures, chloroform and fluctuations in the pH of the environment, has a short latent period with the formation of a high titer of new virions. Phage SAvB14 effectively penetrates the biofilm matrix and destroys the film-forming pathogens of mastitis S. aureus var. bovis and can be used in combination with antibiotics.