Interference of selected essential oils in modulating quorum sensing mechanism in Klebsiella pneumoniae

Klebsiella pneumoniae is associated with healthcare-related infections, and its pathogenicity is linked to quorum sensing (QS), which regulates virulence factor production. The rise in antibiotic resistance poses a significant global challenge, increasing the need for alternative strategies. Targeting the QS system offers a promising approach to attenuate virulence. Thus, identifying stable, non-toxic QS inhibitors from natural sources is essential.

The study aimed to characterize the compounds of lemongrass, patchouli, tea tree, and thyme Essential oils (EOs) with anti-QS effects against K. pneumoniae isolates.

EOs were analyzed for functional groups and compounds using UV-visible spectroscopy (UV-VIS), Fourier Transform Infrared Spectroscopy (FT-IR), and Gas Chromatography Mass Spectrometry (GC-MS). Molecular docking studies identified interactions between EO compounds and QS proteins of K. pneumoniae. Toxicity was assessed in Drosophila melanogaster, and the growth kinetics of K. pneumoniae isolates were measured at sub-inhibitory concentrations (sub-MICs) of EOs over 24 h. Virulence and QS gene expression were quantified.

GC-MS analysis pinpointed specific bioactive compounds found in the EOs. Molecular docking studies indicated α-pinene, azulene, copaene, and thymol with an affinity for QS proteins. LC₅₀ values were significantly higher than 2000 ppm, indicating EOs as safe and non-toxic. Increased generation time and downregulation of QS and virulence genes was observed with the EOs.

This investigation highlights the therapeutic potential of EOs as an alternative strategy for addressing K. pneumoniae infections. To maximize their therapeutic application, further study is required to formulate the EOs and evaluate their potential in in vivo models.