Potencial antimicrobiano do óleo essencial Cinnamomum triplinerve em sinergia com polimixina b contra Klebsiella pneumoniae multirresistente

Abstract

Antimicrobial resistance, especially in carbapenem-resistant and polymyxin-resistant Klebsiella pneumoniae (CRP-Kp), represents a critical challenge in the treatment of severe infection. This study explores the potential of Cinnamomum triplinerve, a plant native to Brazil, whose essential oils were tested alone and in combination with polymyxin B to combat CRP-Kp. Essential oils were extracted from the leaves (CTL) and bark (CTB) of C. triplinerve by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The synergy between the oils and polymyxin B was evaluated by checkerboard assay, including survival curve, spots, and biofilm inhibition. Safety was assessed by hemolysis and cytotoxicity tests using Caenorhabditis elegans. A model technique was applied in C. elegans, and the action of essential oil molecules extracted from leaves with polymyxin B (CTL-PMB) and bark with polymyxin B (CTB-PMB) was observed by scanning electron microscopy (SEM) and cell membrane integrity assay. The main component of the essential oils was (E)-nerolidol. The CTL-PMB and CTB-PMB combinations reduced by 32 times the concentration of polymyxin B required to inhibit bacterial growth, with minimum inhibitory concentrations of 128 µg/mL and 16 µg/mL, respectively. Both transfers effectively inhibited biofilm formation and provided high safety in cytotoxicity assays, without hemolytic effects. Infection models confirmed the efficacy of the CTL-PMB combination, achieving 77.77% survival in C. elegans. SEM images revealed bacterial death without cell membrane rupture. Essential oils of C. triplinerve with polymyxin B show promise as adjuvants for the development of new therapies against CRP-Kp infections.