Antimicrobial susceptibility of Staphylococcus aureus strains against organic acids

Staphylococcus aureus is a pathogen that produces toxins associated with clinical and food-borne diseases. For that reason, it is crucial to monitor and control this microorganism during food production and industrialization to ensure food safety and protect consumers’ health. In light of increasing concerns about bacterial resistance and its impact on public health, organic acids are being considered as potential alternatives to antimicrobials in livestock production. This study aimed to investigate the susceptibility of S. aureus to a blend of organic acids (Acidal ML ® - Impextraco NV) in vitro and in a controlled environment by assessing the Minimal Inhibitory Concentration and Minimum Bactericidal Concentration of the product. The recommended prescription of Acidal ® ML is 0.1% in vivo, but we tested amounts of 0.0125%, 0.025%, 0.05%, 0.10%, 0.20%, 0.25%, and 0.30% in 96-wells microplates using Muller Hinton Broth and 18-hours strains in Brain Heart Infusion (36ºC) and thinned until 0.5 on the MacFarland scale. In this way, the results appointed a Minimal Inhibitory Concentration and Minimum Bactericidal Concentration of Acidal ® ML against the tested Staphylococcus aureus strain of 0.1% and 0.25%, respectively. In conclusion, the concentration recommended by the product’s label proved effective in inhibiting bacterial growth, although a higher amount was necessary for a bactericidal effect. The dosage must be tested in vivo for better comprehension.