Curativos tipo manta de poli ácido lático (PLA) e poli álcool vinílico (PVA) incorporado de óleos essenciais com atividade antimicrobiana sobre Staphylococcus aureus

Abstract

Staphylococcus aureus is a commensal bacterium found in the body of humans and animals, often associated with infectious processes, causing the formation of persistent wounds. It is known that these wounds are difficult to heal, this fact is due to the presence of S. aureus in the form of a biofilm, making its eradication difficult using commercially available antibiotics.Therefore, alternatives are suggested, such as the use of essential oils to control this pathogen. The objective of this work was to develop blanket-type dressings made of polylactic acid (PLA) and polyvinyl alcohol (PVA) incorporated with essential oils, aiming at controlling strains of S. aureus, an agent associated with persistent human wounds. Three strains of S. aureus (GL 8702, GL 8548 and GL 5674) were used, with the inhibitory activity of the essential oils of field mint (Mentha arvensis L.), ylang ylang (Cananga odorata (Lam.) Hook. f. & Thomson), Egyptian geranium (Pelargonium graveolens L'Hér.), tarragon (Artemisia dracunculus), cinnamon (Cinnamomum cassia (L.) J. Presl), lavender (Lavandula angustifolia Mill.), lemon grass (Brazil) (Cymbopogon flexuosus (Nees ex Steud.) W. Watson) and wild rosemary (Baccharis dracunculifolia DC.) were initially evaluated. From initial screening, lavender, cinnamon, lemongrass, geranium and field mint showed significance inhibitory activity against the strains of S. aureus and were selected for further research activities. The minimum bactericidal concentrations (MBC) of the oils were determined using the microdilution technique, with adaptations, where the MBC of cinnamon oil were 0.5; 0.25 and 0.25% (v/v), respectively, for GL 8702 strains; GL 8548 and GL 5674, for the essential oils of field mint, lavender and lemongrass the CMB were equal to 2% and for the geranium oil the CBM was 5% for all strains. Using the Rotational Central Composite Design (DCCR), 45 tests were defined containing different mixtures with different concentrations of essential oils based on the AMC obtained from each one. All mixtures of essential oils generated by the DCCR showed bactericidal activities against the strains of S. aureus, with no growth in plaques being observed for all assays. Thus, three trials were selected for the preparation of PLA and PVA blankets, one containing the lowest concentration of oil mixtures (6.4%), another with 12.9% and the one with the highest concentration of oil mixtures (14.6%) and evaluated. Both blankets were obtained using the blow spinning technique (SBS) and added a mixture of essential oils. There was no significant difference in antimicrobial activity between PLA blankets containing 12.9 and 14.6% essential oils, with an observed reduction of approximately 2.42 Log CFU/mL of S. aureus strains. The same behavior of microorganisms was observed for PVA blankets, around 1.8 Log CFU/mL S. aureus. The FTIR spectra of the two blankets show that there are characteristic peaks of the essential oils contained in the treatments, indicating that there was a good interaction between the functional groups of the polymers and the oils. It is concluded that the blow-spun blanket added with essential oils has great potential to be used as an antimicrobial dressing to aid in the treatment of wounds.