Sensitivity of Staphylococcus aureus cultures of different biological origin to commercial bacteriophages and phages of Staphylococcus aureus var. bovis

Abstract

Background and Aim: Mastitis, an inflammation of the mammary gland, is an ongoing problem in dairy herds. In this study, we determined the sensitivity of Staphylococcus aureus cultures of different biological origins to commercial bacteriophages and phages of S. aureus var. bovis which were isolated on dairy farms, to create a drug for the treatment of mastitis in cows. Materials and Methods: We used cultures of S. aureus isolated from different habitats, and other types of staphylococci isolated on dairy farms. As antibacterial agents, the commercially available bacteriophages staphylococcal bacteriophage and Intestifag and field strains of phages Phage SAvB07, Phage SAvB08, Phage SAvB12, and Phage SAvB14 were used. Evaluation of their lytic properties was performed using the drip method. Results: The drug Intestifag lysed cultures isolated from human habitats and archival strains of S. aureus No.209-P and S. aureus (ATCC 25923) in 91.8%–100% of cases. Staphylococcal bacteriophage killed 3.6 times fewer cultures of S. aureus isolated from humans than Intestifag and did not affect the growth of archival strains. Neither drug lysed cultures isolated from cows or cultures isolated from dairy products sold in agri-food markets. Phage SAvB14 lysed 92.7±8.3% of S. aureus isolated from the mammary glands of cows and 69.2±6.4% of cultures isolated from dairy products sold in agri-food markets. Phage SAvB12, Phage SAvB08, and Phage SAvB07 lysed 1.2-1.7 times fewer cultures isolated from the mammary glands of cows and 6-18 times fewer cultures isolated from dairy products, compared with Phage SAvB14. Phages of S. aureus var. bovis can infect staphylococcal species such as Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus, and Staphylococcus xylosus. The widest range of hosts was found for Phage SAvB14, which indicates its polyvalence. Conclusion: The biological origin of staphylococcal strains must be considered when developing effective phage therapy. Phage SAvB14 appears to be a good candidate for the development of a drug for the treatment of mastitis in cows.