The emergence of multidrug-resistant (MDR) Staphylococcus spp. has resulted in the reduced use of antibiotics in many skincare cosmetic products. Alternative treatments using natural bioactive compounds and chemical agents can be replaced. However, these compounds have induced negative side effects among users and are not environmentally friendly. Phage therapy is an alternative to antibiotics for the treatment of specific pathogenic bacteria including Staphylococcus spp., without harmful effects on human skin cells and microflora. Phages can be potentially used in cosmetic products. The direct application of phage-based cosmetic products on skin can reduce the chance of skin infection caused by pathogenic Staphylococcus spp. In the present work, we isolated 17 Staphylococcus phages from sewage and soil samples. Phage A1 showed the highest lytic ability at 50% (B1 profile), covering 13 tested Staphylococcus isolates including Staphylococcus aureus (SA), methicillin-resistant S. aureus (MRSA), S. capitis (SC), and S. epidermidis (SE). Phage A1 reduced the representative S. aureus ATCC 25923 and S. capitis SC1 by 2.0 ± 0.1 and 4.1 ± 0.3 log units at a multiplicity of infection (MOI) of 10⁴ and by 4.2 ± 0.2 and 4.4 ± 0.5 log units at a MOI of 10⁵ after 6 h of post-phage treatment. The transmission electron microscope revealed that phage A1 was classified in the order Caudovirales of the family Myoviridae based on its appearance. Phage A1 showed optimal survival in the presence of a 0.125% (v/v) solidant DMH suspension after 3 h of post-treatment. Under a phage skincare serum formulation, the titers of phage A1 were reduced by 0.46 and 0.85 log units after storage at 4 and 25 °C, whereas a reduction of 2.96 log units was also observed after storage at 37° for 90 days. This study provides strong evidence for the effectiveness of phage application in cosmetic skincare serum for the treatment of skin diseases caused by MDR and pathogenic Staphylococcus spp. The concept of this study could be advantageous for cosmetic and/or cosmeceutical industries searching for new bioactive ingredients for cosmetic/cosmeceutical products.

Background and Aim: Salmonella is a leading cause of foodborne illnesses worldwide, often linked to poultry products. Antibiotic resistance among Salmonella strains has increased the need for alternative decontamination strategies, such as bacteriophage (phage) therapy. This study evaluates the lytic efficiency, cytotoxicity, and survivability of a Salmonella phage cocktail derived from wastewater sources. Materials and Methods: A total of 251 Salmonella enterica isolates from broiler production chains were tested against two selected phages (WP109 and WP128). The phages were characterized for lytic ability, cytotoxicity on Caco-2 cells, and survivability under simulated gastrointestinal and harsh environmental conditions. A cocktail of the phages was further tested for efficiency at different multiplicities of infection (MOIs) against representative Salmonella strains. Results: Phage WP109 lysed 91.2% of Salmonella isolates, while WP128 lysed 78.2%. The phage cocktail exhibited a significant reduction of Salmonella counts at MOI 104, achieving up to a 4.4 log CFU/mL reduction in vitro. The cocktail maintained 99.9% survivability in simulated gastric conditions and displayed no cytotoxic effects on Caco-2 cells. Moreover, it was resistant to various ionic sanitizers and pH levels ranging from 2 to 11. Conclusion: The developed phage cocktail demonstrated high lytic efficacy, stability, and safety under simulated conditions, highlighting its potential as a biocontrol agent in the broiler production chain. These findings support its application in reducing Salmonella contamination while addressing the challenges posed by antibiotic resistance. Keywords: antibiotic resistance, bacteriophage therapy, food safety, phage cocktail, poultry production, Salmonella.