Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen commonly associated with burn infections.

Aim: This study aimed to evaluate the effect of cholecalciferol (vitamin D3), phylloquinone (vitamin K1) on selected virulence factors, antibiotic activity, and phagocytic activity.

Materials and Methods: A total of 120 burn swab samples were collected and examined for the presence of P. aeruginosa, identified using VITEK 2 system. One P. aeruginosa isolate exhibiting the highest virulence-associated activity was selected. The sub-minimum inhibitory concentrations of vitamin D3 and vitamin K1 were determined. The effect of these treatments was evaluated virulence factors, phagocytic activity, and antibiotic activity. Experiments were performed in triplicates, and the data were expressed as mean ± standard deviation and analyzed using one-way ANOVA followed by Duncan’s multiple range test, with statistical significance set at p < 0.05.

Results: the isolated rate of P. aeruginosa was 53.33%. Vitamin D3 produced the greatest reduction in protease activity (67.94%) and increased phagocytic activity by 16.56%. Vitamin K1 produced the greatest reduction in pyocyanin production (94.58%) and increased the tigecycline inhibition-zone diameter from 9mm to 16 mm. The combined treatment produced the greatest inhibition of biofilm formation (98.32%).