Avaliação da atividade antibacteriana do óleo essencial de canela em bactérias produtoras de carbapenemases

Abstract

Introduction: The emergence of bacterial multidrug resistance is an important public health problem that has resulted in the need to explore novel therapeutic options. There is a wide variety of antibacterial targets not used by the current drugs to be exploited. The objective of the present study was the investigation of the antibacterial activity of Cinnamomum cassia L. essential oil (CCeo) alone and in combination with polymyxin B (POL) against carbapenemaseproducing Gram-negative bacteria: Enterobacter cloacae, Klebsiella pneumoniae and Serratia marcescens. Methodology: Bacterial identification was performed by Vitek ® 2, BD Phoenix TM 100 and MALDI-ToF ToF . Antibacterial susceptibility was determined by broth microdilution and MALDI-ToF ToF . The presence of beta-lactamase-encoding genes was assessed by PCR. The antibacterial activity of CCeo was evaluated using the agar disk diffusion, broth microdilution, time-kill and checkboard methods. Possible CCeo mechanism of action was assessed by PCR, RT -PCR, RT -qPCR, and protein leakage assay . Results: The carbapenemase production was confirmed by MALDI-ToF ToF and PCR showed the presence of blaKPC-2 for all the studied strains and also blaIMP-10 for S. marcescens. CCeo exhibited a inhibitory effect against carbapenem-resistant E. cloacae (MIC, 17,57 μg.mL -1 ), K. pneumoniae (MIC, 281.25 μg.mL -1 ) and S. marcescens (MIC, 281.25 μg.mL -1 ). The survival curves of the strains showed a decrease in viable cell counts over time and when CCeo was tested in association with POL against K. pneumoniae and S. marcescens, synergism was confirmed. It was observed protein leakage when S. marcescens was treated with increasing concentrations of CCeo and CCeo + POL. Conclusions: CCeo presents antibacterial activity against the studied strains and when CCeo is associated with POL, a synergistic effect is able to inhibit bacterial growth rapidly and consistently, making it an interesting candidate for development of alternative treatment for carbapenemase-producing strains. CCeo destabilizes the outer membrane of the bacterium, making possible the cell entrance of the POL in the periplasmic space allowing its action and leading to cell death.