Atividade antimicrobiana e modulatória do óleo essencial microencapsulado de Syzygium aromaticum em Staphylococcus aureus multirresistentes

Abstract

Essential oils (EOs) are secondary metabolites extracted from different parts of plants, but their low physicochemical stability limits their practical use. To overcome this problem, microencapsulation has been used as a strategy to protect their volatile compounds, increasing stability during handling, processing and storage. The aim of this study was to evaluate the antimicrobial and modulatory activity of free and microencapsulated Syzygium aromaticum essential oil (OESAM) against multidrug-resistant bacteria. Twenty-four strains of Staphylococcus aureus from different herds in the north of Minas Gerais were selected by MALDI-TOF MS mass spectrometry. Antibiograms, sensitivity tests with different concentrations of pure EO and microencapsulated EO, evaluation of their modulation, as well as seeking to understand the role of whey protein isolate WPI 90%, used in the wall of microcapsules, in potentiating antimicrobials, were carried out using bioinformatics analysis. The resistance profile for Ampicillin + Sulbactam was 95.83% of the isolates, followed by Meropenem (87.5%), Oxacillin (79.16%), Cefoxitin (37.5%) and Imipenem (4.16%) . Analysis by gas chromatography with mass spectrometry (GC-MS) identified eugenol as the main component of clove essential oil. With regard to sensitivity tests, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for the antibiotic oxacillin showed MIC values ranging from 40 to 60 μl/ml and MBC values from 40 to 110 μl/ml. Meropenem showed MIC values between 5 and 40 μl/ml and CBM values between 10 and 60 μl/ml. The pure oil showed a MIC of 10 μl/ml for 100% of the strains tested and a CBM of 20 μl/ml and 40 μl/ml. And the modulating activity was evaluated using the checkerboard method, revealing a 16-fold reduction in the MIC values of the antibiotics and a 4 to 8-fold reduction in the MIC values of the essential oil. The effect of (OESAM) was also evaluated using the complex coacervation technique in the microencapsulation process. The inhibitory activity of (OESAM), associated or not with beta-lactam antibiotics, was tested against 10 isolates of multidrug-resistant strains of S. aureus. A significant difference was observed in the minimum inhibitory concentrations of the antibiotics oxacillin and meropenem alone and combined with OESAM (p<0.05). There was an average reduction of 12 and 51μg.ml-1 in the minimum inhibitory concentration of OESAM when combined with the antibiotics oxacillin and meropenem, respectively. There was an average reduction in antimicrobial doses of up to 2.7 times when combined with OESAM. Although in some S. aureus strains an indifferent effect was observed between OESAM and the antibiotics, the effects of synergism and additivity stood out. Bioinformatic analysis revealed three clusters in the protein interaction network. This study demonstrated the potential of using OESA and OESAM in combination with beta-lactam antibiotics to combat multi-resistant strains of S. aureus, mitigating the resistance mechanisms of these bacteria to conventional antimicrobials.