Additive Effects of Natural Plant Extracts/Essential Oils and Probiotics as an Antipathogenic Topical Skin Patch Solution for Acne and Eczema

This work leverages the additive antipathogenic effects of natural extracts/essential oils (EOs) and probiotics for the treatment of acne vulgaris associated with Cutibacterium acnes (C. acnes) and eczema complicated by secondary infections with Staphylococcus aureus (S. aureus). Six probiotic strains and various extracts/EOs were evaluated in a large screening to evaluate their potential against both pathogens. Lacticaseibacillus paracasei PCB003 was able to inhibit the growth of both pathogens. For extracts/EOs, Oregano EO had the best antipathogenic effects on both pathogens and did not show any adverse impact on the growth of probiotics, making it suitable for simultaneous use. Using Lactiplantibacillus plantarum PCB011 as a probiotic model, five material formulations were assessed for their suitability to protect probiotic cells within freeze-dried topical patches. Alginate and trehalose (ALG+TRE) and thermoplastic starch (TPS) had the highest probiotic survivability, with ALG+TRE chosen as the final patch material as it was more robust. PCB003 and PCB011 were individually incorporated into the ALG+TRE freeze-dried matrix to form a 6 mm patch; both ALG+TRE (PCB003) and ALG+TRE (PCB011) patches, when used individually, successfully inhibited C. acnes growth by 4.7 and 6.0 mm, respectively, surpassing the performance of commercially available acne patches. The additive effect with 30% Oregano EO further improved pathogen inhibition. For S. aureus, the incorporation of 30% Oregano EO to ALG+TRE (PCB003) increased the size of the inhibition zone more than 10-fold. For C. acnes, the ALG+TRE (PCB003) patch with 30% Oregano EO demonstrated an inhibition zone of 16.3 mm, and the ALG+TRE (PCB011) patch with 30% Oregano EO achieved a 14.3 mm inhibition zone. Genomic analysis confirmed that PCB003 and PCB011 lack antimicrobial resistance determinants, ensuring safety. This study successfully combined probiotics and natural agents to create effective dermatological antipathogenic patches.