Acetic acid exerts bactericidal activity against the common burn wound pathogens Staphylococcus aureus and Pseudomonas aeruginosa without generating resistance

Staphylococcus aureus and Pseudomonas aeruginosa are two of the most common pathogens colonising burn wounds in hospitals. Resistance or tolerance to antimicrobials, due to biofilm formation, complicates treatment and increases morbidity, highlighting that current approaches to burn wound care are insufficient. Therefore, novel antimicrobial treatments are needed. In this study we characterise the antimicrobial activity of acetic acid against S. aureus and P. aeruginosa. Our results demonstrate that acetic acid exerts potent antimicrobial activity against both pathogens, including those growing within biofilms, and bacteria that are not actively dividing. The concentrations of acetic acid required to achieve antimicrobial effects were well below the therapeutically tolerated range. We also found that resistance to acetic acid did not develop in vitro , suggesting that the likelihood of resistance emerging in a single step is low. Additionally, application of acetic acid, within a Gellan hydrogel-based dressing, effectively reduced bacterial burden in a porcine ex vivo model of skin colonisation. Together, our findings support the potential of acetic acid as a promising topical antimicrobial agent for preventing burn wound infections by demonstrating that acetic acid is active against bacteria in various growth states and showing for the first time that resistance does not develop easily in vitro . These results suggest that could be a suitable candidate for the clinical management of burn wounds in the future.