Atividade antimicrobiana dos óleos essenciais Thymus vulgaris L. e Cymbopogon martinii e de seus constituintes majoritários frente à Klebsiella pneumoniae, Pseudomonas aeruginosa PA01 e Candida albicans em biofilme formado em sonda urinária

Abstract

Pseudomonas aeruginosa as well as Klebsiella pneumoniae are Gram-negative bacteria commonly found in the hospital environment and also cause infections in immunocompromised patients Candida are responsible for causing fungal infections worldwide, with C. albicans being the species most frequently associated with infectious processes in hospitalized patients . These microorganisms are currently studied, due to their great involvement in the formation of biofilms and in the increase of resistance to antimicrobials. In this context, the objective of the present study was initially to carry out a systematic review on biofilms and antimicrobial activity of thyme, cinnamon and palmarosa essential oils and their constituents against K. pneumoniae. Subsequently, the antimicrobial and synergistic activity of thyme and palmarosa essential oils and their major constituents, and their anti-biofilm activity in urinary catheters, were evaluated. The minimum inhibitory concentration (CIM), the minimum bactericidal concentration and the minimum fungicidal concentration (MFC) were evaluated by the microdilution method in 96-well plates (CLSI M7-A6, 2013 CLSI and M44-A2, 2008) using a strain of C albicans (ATCC 14053), C. glabrata, K. pneumoniae and P. aeruginosa strain PA01, respectively. The effect of EO and CM on the growth of these microorganisms was evaluated by performing a growth curve over time and the synergistic effect was also determined. Antibiofilm activity after treatment with EO and CM was evaluated using crystal violet assay methodologies, determination of total proteins, synergism, growth curve, atomic force microscopy. For Candida spp. the inhibition test of the formation of germ tube and pseudohyphae was also performed, as well as calcofluor staining. As for the bacteria, the techniques of inhibition of the production of exopolysaccharides were used, and for P. aeruginosa, the tests of inhibition of the production of pyocyanin and the motility test were also carried out. From the results obtained, it was evidenced in all tests performed that there was a significant decrease in biofilm formation. For the crystal violet staining assays, the best results were for palmarosa oil and the major constituent geraniol, which showed up to 86% reduction in biofilm formation for bacteria at a concentration of 1xcim. As for Candida, palmarosa and eugenol showed a reduction of 85% in the concentration of 1xCIM. In the determination of proteins, the oil that stood out the most was also palmarosa and eugenol with a reduction of 84.4% in the concentration of 1x MIC for bacteria. As for Candida a palmarosa and geraniol that presented greater reductions reaching 79% in the concentration of 1xcIM. For P. aeruginosa PA01, in the motility tests, the oils that best stood out were palmarosa and thyme, which even showed 100% reduction in motility. In the germ tube formation inhibition tests in Candida albicans, the best results were thyme, palmarosa and geraniol which showed 100% inhibition in all tested concentrations. For inhibition of pseudohyphal formation, all compounds showed a significant reduction in pseudohyphal formation. In our results, essential oils and their major constituents demonstrated antibiofilm activity in hospital medical material, showing excellent promise in controlling biofilm formation and as an effective therapeutic alternative against microbial resistance.