Introduction: Bacterial antimicrobial resistance is a global challenge that threatens the effectiveness of antibiotics and leads to higher mortality rates. Beyond health concerns, the lack of control in the use of antimicrobial agents also presents a higher risk to the environment and biodiversity. As bacterial resistance to antibiotics continues to rise, this study explored the potential of organic acids in managing MRSA biofilms. Organic acids disrupt bacterial processes by lowering the inner membrane pH levels, damaging cells and ultimately inhibiting bacterial reproduction or causing cell death. Purpose: The objective of the thesis was to evaluate the ability of organic acids to control MRSA biofilms. Methods: First, we assessed the antibacterial potential of ascorbic, acetic, citric and lactic acids by determining their minimal inhibitory concentrations. We used various methods to investigate these acids' effects on MRSA biofilms. Optical density measurements were used to assess total biofilm biomass, while enzyme activity and colony-counting methods were used to evaluate bacterial activity within the biofilm. Additionally, we examined the impact of acids on membrane integrity and oxidative stress in bacteria. Results: The results confirmed the inhibitory and bactericidal properties of the acids against MRSA biofilms. Organic acids effectively reduced both biofilm biomass and cell count. The strongest reduction was observed in the dehydrogenase activity. Higher concentrations of acids had a greater impact on membrane integrity and oxidative stress compared to lower concentrations. Discussion and conclusion: Our findings suggest that organic acids hold significant potential for eliminating MRSA biofilms. Lactic acid proved to be the most effective across all methods, while the effects of ascorbic, acetic and citric acids varied depending on the method. We can conclude that each acid acts differently on bacterial biofilms. In addition to their bactericidal properties, organic acids are affordable and have a lower environmental impact compared to conventional antimicrobial agents. Notably, increased acid concentration did not always result in greater efficacy. However, higher concentrations did have a stronger effect on dehydrogenase activity, membrane integrity and oxidative stress in biofilm bacteria.
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