High efficacy of a characterized lytic bacteriophage in combination with thyme essential oil against multidrug-resistant Staphylococcus aureus in chicken products

Background: The emergence and spread of methicillin-resistant Staphylococcus aureus (MRSA) in the food industry have led to using alternative natural bioagents for controlling S. aureus in food. Aims: The current work aimed to isolate and characterize a lytic phage specific to S. aureus and evaluate its efficacy with thyme essential oil for controlling S. aureus growth in chicken fillets. Methods: Twenty S. aureus strains previously isolated from ready-to-eat chicken products were tested for antimicrobial susceptibility and used for phage isolation. Results: All S. aureus strains were multidrug-resistant (MDR). The isolated phage (vB_SauM_CP9) belonged to the family Myoviridae and maintained its stability at pH (4-9) and temperature (30-70°C). The phage showed lytic activity on ten S. aureus strains and had a burst size (228 PFU/infected cell), latent period (45 min), and rise period (15 min). A combination of S. aureus phage multiplicity of infection (MOI) 10 + thyme oil 1% caused a higher significant reduction in S. aureus growth (87.22%) in artificially inoculated chicken fillets than individual treatment with bacteriophage or thyme essential oil. Conclusion: To our knowledge, this is the first report to evaluate the efficacy of bacteriophage and thyme oil for controlling the growth of MDR S. aureus in chicken products and recommending application of S. aureus phage and thyme oil combination in the food industry to achieve food safety goals and consumer protection as well as mitigate the antimicrobial resistance crisis.