Antimicrobial Efficacy of Four Thieves Vinegar Against Pneumonia-Associated Respiratory Pathogens: A Sustainable and Edible Disinfectant Approach

The aim of this study was to assess the antimicrobial efficacy of different Four Thieves Vinegar (FTV) variants, including annual, monthly and commercial FTV, against pneumonia-associated respiratory pathogens (PARPs) isolates. The well diffusion agar method was used to test the antimicrobial activity against 23 PARPs isolates such as Staphylococcus aureus (3 isolates), Acinetobacter baumannii (9 isolates), Klebsiella pneumoniae (6 isolates), and Pseudomonas aeruginosa (5 isolates). FTV was prepared by fermenting apple cider vinegar with selected several medicinal and aromatic herbs such as sage, rosemary, cinnamon, mint and lavender and others in a 3:2 ratio of apple cider vinegar to water under controlled conditions for monthly and annual incubation periods. Samples were tested in pure (100%) and 50% diluted forms. Among the variants tested, annual FTV showed the strongest inhibitory effect. The inhibition zones ranged from 19.52 mm to 16.70 mm for K. pneumoniae and 19.65 mm to 14.71 mm for A. baumannii. In contrast, monthly FTV and Apple-V showed moderate antimicrobial activity, while Commercial FTV showed the lowest efficacy, indicating that traditional fermentation enhances antimicrobial potency. The pure (100%) FTV samples generally showed larger inhibition zones than the 50% diluted samples, confirming the concentration-dependent efficacy of FTV. The antimicrobial effects varied with fermentation time and vinegar composition, with longer fermentation times correlating with stronger inhibitory activity. FTV showed strong antimicrobial potential against PARPs, making it a natural alternative to chemical disinfectants and highlighting the value of traditional methods. Further research should optimise formulations and assess stability against other hospital-acquired multidrug-resistant pathogens.